Rotation angle detection device

Abstract

The rotation angle detection device includes a first detection unit (210), a second detection unit (230), and a calculation unit (250). The first detection unit detects a first rotation angle of the steering shaft (102) that rotates in conjunction with the steering wheel (101). The second detection unit detects a second rotation angle of the motor shaft (301) that is connected to the steering shaft via a reduction mechanism (302). The calculation unit receives the first rotation angle from the first detection unit and the second rotation angle from the second detection unit, and calculates the steering angle of the steering shaft based on the difference between the first and second rotation angles.

Description

[0001] Cross-reference of related applications

[0002] This application is based on Japanese Patent Application No. 2020-190049, filed on November 16, 2020, the contents of which are incorporated herein by reference. Technical Field

[0003] This invention relates to a rotation angle detection device. Background Technology

[0004] Previously, for example, Patent Document 1 proposed a rudder angle detection device for detecting the steering angle of a vehicle's steering shaft. The rudder angle detection device includes a vernier calculation unit, a neutral period determination unit, and a neutral point determination unit.

[0005] The vernier calculation unit calculates the reference angle based on the motor angle and the steering shaft angle. The neutral period determination unit inputs the inferred or measured self-aligning torque value. The neutral period determination unit determines the neutral period of the reference angle based on the self-aligning torque value.

[0006] The neutral point determination unit inputs the pre-stored reference angle value of the handle neutral point as the neutral point value. The neutral point determination unit inputs an angle signal containing the neutral period from the neutral period determination unit. Furthermore, the neutral point determination unit obtains the steering angle based on the neutral point value and the angle signal.

[0007] Existing technical documents

[0008] Patent documents

[0009] Patent Document 1: International Publication No. 2016 / 132878 Summary of the Invention

[0010] However, in the aforementioned prior art, a self-aligning torque value is required to obtain the steering angle. Therefore, the steering angle detection device requires a complex inference mechanism for inferring the self-aligning torque value and a measurement mechanism for determining the self-aligning torque value.

[0011] The purpose of this application is to provide a rotation angle detection device that simplifies rudder angle calculation without requiring a self-correcting torque value.

[0012] According to one aspect of this application, the rotation angle detection device includes a first detection unit, a second detection unit, and a calculation unit.

[0013] The first detection unit detects the first rotation angle of the steering shaft, which rotates in conjunction with the steering wheel. The second detection unit detects the second rotation angle of the motor shaft, which is connected to the steering shaft via a reduction gear.

[0014] The calculation unit inputs a first rotation angle from the first detection unit and a second rotation angle from the second detection unit, and calculates the rudder angle of the steering shaft based on the difference angle between the first rotation angle and the second rotation angle.

[0015] Therefore, the steering shaft rudder angle is calculated based on the difference between the first rotation angle of the steering shaft and the second rotation angle of the motor shaft. Thus, the self-centering torque value is not required, simplifying the calculation of the steering shaft rudder angle. Attached Figure Description

[0016] The above and other objects, features, and advantages of this application will become more apparent from the following detailed description with reference to the accompanying drawings. The drawings are as follows.

[0017] Figure 1 This is a diagram showing the steering system of the first embodiment.

[0018] Figure 2 This is an exploded 3D view of the rudder angle sensor.

[0019] Figure 3 It is a cross-sectional view showing the electric motor and the motor control device.

[0020] Figure 4 This is a diagram showing the output of the rudder angle sensor and the output of the rotation angle sensor.

[0021] Figure 5 It is a diagram showing the relationship between the difference angle between the first and second rotation angles and the rudder angle.

[0022] Figure 6 This is a diagram showing the rudder angle in the second embodiment, where the output of the rudder angle sensor differs significantly from the output of the rotation angle sensor.

[0023] Figure 7 It means Figure 6 The diagram shows the relationship between the difference angle of each rotation angle and the rudder angle.

[0024] Figure 8 This is a perspective view of the magnet of the rudder angle sensor according to the second embodiment.

[0025] Figure 9 This is a diagram showing the arithmetic unit of the third embodiment.

[0026] Figure 10 This diagram shows the output of the rudder angle sensor being amplified by 5 times.

[0027] Figure 11 This is a flowchart showing the angle correction processing of the arithmetic unit.

[0028] Figure 12It is a diagram representing an angle waveform that has been corrected to become an integer multiple of an angle.

[0029] Figure 13 This is a graph showing the relationship between the magnified rudder angle detection range and the difference angle.

[0030] Figure 14 This is an exploded perspective view of the torque sensor according to the third embodiment.

[0031] Figure 15 This is a side view of the torque sensor according to the third embodiment. Detailed Implementation

[0032] Hereinafter, various methods for implementing this application will be described with reference to the accompanying drawings. In each embodiment, sometimes the same reference numerals are used for parts corresponding to matters described in prior embodiments, and repeated descriptions are omitted. In each embodiment, where only a part of the structure is described, other previously described embodiments can be applied to the other parts of the structure. Not only are the combinable parts specifically shown to be combinable to each other in each embodiment, but embodiments can also be partially combined to each other even if not explicitly shown, provided that the combination does not particularly create an obstacle.

[0033] (First Implementation)

[0034] The first embodiment will now be described with reference to the accompanying drawings. Figure 1 As shown, the steering system 100 includes a steering wheel 101, a steering shaft 102, a pinion 103, a rack shaft 104, a wheel 105, a rotation angle detection device 200, and an electric power steering device 300.

[0035] The steering wheel 101 is a steering component operated by the driver. The steering shaft 102 is linked to the steering wheel 101 and rotates around a pivot axis. The pinion 103 converts the rotation of the steering shaft 102 into the action of the rack and pinion 104. The wheel 105 is connected to the rack and pinion 104.

[0036] The rotation angle detection device 200 is a device for determining the rudder angle of the steering shaft 102. For example... Figures 1-3 As shown, the rotation angle detection device 200 includes a rudder angle sensor 210, a rotation angle sensor 230, and a calculation unit 250.

[0037] The electric power steering system 300 is a steering device that allows the driver to operate the steering wheel 101 with less force. For example... Figure 1As shown, the electric power steering 300 rotates the motor shaft 301 according to a command. As a result, the electric power steering 300 imparts torque to the steering shaft 102 via a reduction gear 302. The reduction gear 302 is a reduction gear that mechanically transmits the rotation of the motor shaft 301 to the steering shaft 102.

[0038] The rudder angle sensor 210 of the rotation angle detection device 200 detects the first rotation angle of the steering shaft 102. The first rotation angle is an absolute angle of 0° to 360°. Figure 2 As shown, the rudder angle sensor 210 includes housings 211 and 212, a drive gear 213, a driven gear 214, a magnet 215, a magnetic flux detection unit 216, a substrate 217, and a connector 218.

[0039] Housings 211 and 212 are assembled together to house components such as the drive gear 213. Housings 211 and 212 are passed through by the steering shaft 102 and are fixed in position relative to the steering shaft 102.

[0040] The drive gear 213 is fixed to the steering shaft 102 and rotates in conjunction with the steering shaft 102. The driven gear 214 meshes with the drive gear 213 and rotates in conjunction with the drive gear 213. The driven gear 214 is disposed in a recess of the housing 212.

[0041] Magnet 215 is a diode magnet consisting of a pair of N poles and a S pole magnetized radially along the steering shaft 102. Magnet 215 is fixed to driven gear 214 and rotates together with driven gear 214. Magnetic flux detection unit 216 detects the first rotation angle of steering shaft 102 based on the change in magnetic flux received from magnet 215.

[0042] The magnetic flux detection unit 216 is configured as a molded body including a Hall element and a magnetoresistive element. The magnetic flux detection unit 216 is mounted on the substrate 217. Compared with angle detection mechanisms such as potentiometers and rotary encoders, the magnetic detection method is superior in terms of cost, size, durability, and mass production.

[0043] The substrate 217 is, for example, a printed circuit board. The connector 218 is connected to wiring for outputting the detection results of the magnetic flux detection unit 216 to the computing unit 250.

[0044] The rotation angle sensor 230 is housed in the electric power steering system 300. The rotation angle sensor 230 detects a second rotation angle of the motor shaft 301. The second rotation angle is an absolute angle of 0° to 360°. The rotation angle sensor 230 is configured as a magnetic type or a rotary transformer type rotation angle sensor as described above.

[0045] The calculation unit 250 receives information about a first rotation angle from the steering angle sensor 210 and information about a second rotation angle from the rotation angle sensor 230 within the electric power steering system 300. Based on the difference between the first and second rotation angles, the calculation unit 250 calculates the steering angle of the steering shaft 102. The calculation unit 250 is housed within the steering angle sensor 210 and the electric power steering system 300. Alternatively, the calculation unit 250 may be installed separately in the vehicle.

[0046] like Figure 1 , Figure 3 As shown, the electric power steering system 300, in addition to the reduction mechanism 302, also includes a torque sensor 310, an electric motor 330, and an electric motor control device 350. The torque sensor 310 detects the steering torque input by the driver operating the steering wheel 101. The torque sensor 310 is located on the steering shaft 102.

[0047] The 330 motor is a brushless EPS (Electric Power Steering) motor. For example... Figure 3 As shown, the electric motor 330 has a housing 331, a motor shaft 301, a rotor 332, a magnet 333, a stator 334, and a winding 335.

[0048] The motor shaft 301 is rotatably mounted on the housing 331 with the rotation axis as its center. The motor shaft 301 is supported by bearings located on the housing 331. The motor shaft 301 is connected to the reduction mechanism 302. The rotor 332 is fixed to the motor shaft 301. A magnet 333 is located on the rotor 332. The stator 334 is fixed to the housing 331 and has windings 335 wound around it.

[0049] The motor control device 350 is housed within the housing 331 of the motor 330. The motor control device 350 has a base plate 351. Electronic components (not shown) for controlling the motor 330 are mounted on the base plate 351. The motor control device 350 controls the motor 330 based on a second rotation angle detected by the rotation angle sensor 230.

[0050] The rotation angle sensor 230 includes a magnet 231 and a magnetic flux detection unit 232. The magnet 231 is fixed to the end face of the motor shaft 301. The magnet 231 is a diode magnet consisting of a pair of N poles and a S pole magnetized radially along the motor shaft 301. The magnetic flux detection unit 232 is mounted on the substrate 351 opposite to the magnet 231. The rotation angle sensor 230 is used in both the rotation angle detection device 200 and the electric power steering device 300.

[0051] Next, the principle of the steering angle detection of the steering shaft 102 will be explained. The steering angle sensor 210 detects the first rotation angle of the steering shaft 102. The rotation angle sensor 230 detects the second rotation angle of the motor shaft 301.

[0052] like Figure 4 As shown, during one revolution of the steering shaft 102, the first rotation angle output by the rudder angle sensor 210 is different from the second rotation angle output by the rotation angle sensor 230. Furthermore, the arithmetic unit 250 performs a vernier calculation. That is, the arithmetic unit 250 calculates the difference angle between the first and second rotation angles. Therefore, as... Figure 5 As shown, the rudder angle relative to the difference angle can be obtained. Therefore, the calculation unit 250 can infer the rudder angle based on the difference angle between the first rotation angle and the second rotation angle.

[0053] Here, in order to uniquely determine the rudder angle within any rudder angle range, it is sufficient to make the difference angle within any rudder angle range smaller than the angle that can be detected by the rudder angle sensor 210 and the magnetic flux detection unit 232.

[0054] Specifically, the first reduction ratio of the reduction mechanism 302 between the steering shaft 102 and the motor shaft 301 is defined as Z. EPS The second reduction ratio between the driving gear 213 and the driven gear 214 is defined as Z. angle The reduction ratio is the gear ratio.

[0055] Furthermore, the rudder angle range obtained by the calculation unit 250 is defined as θ. For example, when the steering wheel 101 is rotated from -500° to +500°, the rudder angle range θ is 1000°. The rudder angle range θ can also be set to 2000°.

[0056] Moreover, the first reduction ratio Z EPS Second reduction ratio Z angle And the rudder angle range θ is set to satisfy

[0057] |(Z EPS -Z angle )×θ|<360°

[0058] or,

[0059] |(Z EPS -Z angle )×θ|<180°

[0060] The conditions are met. Therefore, the arithmetic unit 250 can easily and uniquely determine the rudder angle through vernier calculation.

[0061] The conditions are divided into 360° and 180° because they depend on the detection elements used in the flux detection units 216 and 232. For example, when GMR (Giant Magneto Resistance) or TMR (Tunneling Magneto Resistance) is used as the detection element in the flux detection units 216 and 232, conditions less than 360° are applicable. When AMR (Anisotropic Magneto Resistance) is used as the detection element in the flux detection units 216 and 232, conditions less than 180° are applicable.

[0062] As explained above, in this embodiment, the steering angle of the steering shaft 102 is calculated based on the difference between the first rotation angle of the steering shaft 102 and the second rotation angle of the motor shaft 301. Therefore, a self-centering torque value is not required. Similarly, a complex inference mechanism for inferring the self-centering torque value and a measurement mechanism for determining the self-centering torque value are also unnecessary. Therefore, the calculation of the steering angle of the steering shaft 102 can be simplified.

[0063] Furthermore, the rudder angle sensor 210 can be configured to include a drive gear 213, a driven gear 214, a magnet 215, and a magnetic flux detection unit 216. Therefore, the rudder angle sensor 210 and the rotation angle detection device 200 can be significantly reduced in cost and miniaturized.

[0064] In addition, in this embodiment, the rudder angle sensor 210 corresponds to the first detection unit, and the rotation angle sensor 230 corresponds to the second detection unit.

[0065] (Second Implementation)

[0066] In this embodiment, the differences from the first embodiment will be mainly described. Generally, the first reduction ratio Z of the reduction mechanism 302 is... EPS Although it varies depending on the vehicle type, it is approximately 13 to 20:1. In contrast, due to the size limitations of the steering angle sensor 210, the second reduction ratio Z between the drive gear 213 and the driven gear 214 is... angle A ratio of approximately 2 to 4:1 is considered realistic. Therefore, when a two-pole magnet 215 is used for the rudder angle sensor 210, the difference between the gear ratio of the electric power steering system 300 and the gear ratio of the rudder angle sensor 210 becomes larger. Consequently, there is a possibility that a sufficient rudder angle detection range cannot be guaranteed.

[0067] For example, the first reduction ratio Z of the reduction mechanism 302 of the electric power steering device 300 EPS Set to 18.5. Additionally, the second reduction ratio Z between the driving gear 213 and the driven gear 214 is... angleLet's set it as 78:21 = 3.71. In this case, if... Figure 6 As shown, during one revolution of the steering shaft 102, the first rotation angle of the steering shaft 102 differs significantly from the second rotation angle of the motor shaft 301. Furthermore, as... Figure 7 As shown, when the rudder angle is calculated using vernier calculations, the range of the rudder angle is uniquely limited to 0° to approximately 25°.

[0068] Therefore, in this embodiment, as Figure 8 As shown, the magnet 215 of the rudder angle sensor 210 is configured as a multipole magnet. Therefore, the magnet 215 generates multiple cycles of magnetic flux change during one revolution of the driven gear 214. The magnetic flux detection unit 216 is arranged side-to-side with the magnet 215.

[0069] Furthermore, in order to uniquely determine the rudder angle within any rudder angle range, the number of pole pairs of magnet 215 is defined as P. angle The pole pair number is the number of pairs of N poles and S poles. Figure 8 The magnet 215 shown has three pole pairs, therefore the number of pole pairs is 3. The number of pole pairs must be at least 2.

[0070] Therefore, the first reduction ratio Z EPS Second reduction ratio Z angle P, the number of extreme pairs angle And the rudder angle range θ is set to satisfy

[0071] |(Z EPS -Z angle ×P angle )×θ|<360°

[0072] or,

[0073] |(Z EPS -Z angle ×P angle )×θ|<180°

[0074] conditions.

[0075] By satisfying the above conditions, it is possible to reduce (Z) EPS -Z angle ×P angle The value of ) can reduce the difference between the rotation period of the steering shaft 102 and the rotation period of the motor shaft 301. Therefore, a sufficient rudder angle detection range can be ensured.

[0076] (Third Implementation)

[0077] In this embodiment, the differences from the first and second embodiments will be mainly described. In recent years, the steering angle detection range of the steering shaft 102 has been increasing. In typical vehicles, the steering wheel 101 rotates approximately 3 times. However, there is also a demand to detect rotations of 6 times or more. In the second embodiment, the range of detectable steering angles is expanded by multiplying the magnet 215, but there are physical limits to increasing the number of magnetic poles of the magnet 215.

[0078] Therefore, in this embodiment, the detection range of the rudder angle is expanded by software calculations within the limitations of the body size. Specifically, as... Figure 9 As shown, the arithmetic unit 250 includes an angle correction unit 251. The angle correction unit 251 makes the angle period of the first rotation angle an integer multiple. In this way, by making the output of the rudder angle sensor 210 an integer multiple, the gear ratio can be virtually increased.

[0079] For example, if the second reduction ratio Z between the driving gear 213 and the driven gear 214 angle If set to approximately 3.71, then there will be a 3.71-cycle variation during one revolution of the steering wheel 101. Conversely, the cycle can be set as an integer multiple, for example, 5 times. This will result in a second reduction ratio Z between the driving gear 213 and the driven gear 214. angle The virtual gear ratio that is an integer multiple is defined as N.

[0080] Therefore, the first reduction ratio Z EPS Second reduction ratio Z angle The virtual gear ratio N and the rudder angle range θ are set to meet the following requirements.

[0081] |(Z EPS -Z angle ×N)×θ|<360°

[0082] or,

[0083] |(Z EPS -Z angle ×N)×θ|<180°

[0084] conditions.

[0085] With the virtual gear ratio N set to 5, the output of the rudder angle sensor 210 becomes 5. Therefore, as... Figure 10 As shown, the output of the rudder angle sensor 210 is corrected to an angle waveform equivalent to a gear ratio of 18.55.

[0086] Specifically, such as Figure 11 Angle correction processing is performed as shown. This angle correction processing is executed by the arithmetic unit 250. Additionally, the virtual gear ratio N is set to 3.

[0087] First, in step S261, the virtual gear ratio N is defined. For example, it is set to N = 3. Next, in step S262, it is set to a threshold θ. th =0°. In step S263, a first rotation angle is obtained as the output of the rudder angle sensor 210. For example, the first rotation angle is set to θ = 125°.

[0088] Next, in step S264, it is determined whether the first rotation angle θ is satisfied. th ≤θ<θ th +(360° / N) condition. Since N=3, θ th =0°, therefore, it is determined whether the condition 0°<θ<120° is satisfied. Since θ=125°, the condition of step S264 is not satisfied. Therefore, proceed to step S265.

[0089] In step S265, the threshold θ th Reset to the threshold θ th =θ th +(360° / N). Since N=3, θ th =0°, therefore θ th =0° + (360° / 3) = 120°. After this, return to step S264.

[0090] In step S264, based on the redefined threshold θ th Determine if the condition is met. Since the threshold has been reset to θ. th =120°, therefore θ = 125° satisfies the condition 120° < θ < 240°. Therefore, proceed to step S266. Alternatively, if the condition of step S264 is not satisfied, repeat steps S265 and S264.

[0091] In step S266, θ1 = θ - θ is obtained. th Since θ = 125°, the threshold θ th =120°, therefore θ1 = 5°. In step S267, θ2 = N × θ1 is obtained. Since N = 3 and θ1 = 5°, θ2 = 15°. In other words, the first rotation angle of 125° is corrected to 15°. Thus, the angle correction process is complete. Therefore, as Figure 12 As shown, the first rotation angle of 125° of the rudder angle sensor 210 is corrected to make the rotation angle a 3 times angle waveform.

[0092] Through the above angle correction process, since the gear ratio between the driving gear 213 and the driven gear 214 of the rudder angle sensor 210 can be virtually increased, therefore (Z EPS -Z angle The value of (×N) decreases. Therefore, as Figure 13As shown, the rudder angle detection range can be expanded to over 2000°. The virtual gear ratio N can be appropriately set within an integer range based on the rudder angle detection range.

[0093] As a variation, magnet 215 can also be multipolarized. In this case, the first reduction ratio Z EPS Second reduction ratio Z angle P, the number of extreme pairs angle The virtual gear ratio N and the rudder angle range θ are set to meet the following requirements.

[0094] |(Z EPS -Z angle ×P angle ×N)×θ|<360°

[0095] or,

[0096] |(Z EPS -Z angle ×P angle ×N)×θ|<180°

[0097] conditions.

[0098] (Fourth Implementation)

[0099] In this embodiment, the differences from the embodiments described above will be mainly explained. In this embodiment, the first rotation angle is detected using a torque sensor 310 that detects the rotational torque of the steering shaft 102.

[0100] like Figure 14 as well as Figure 15 As shown, the torque sensor 310 includes a magnet 311, a yoke 312 and 313, a torsion bar 314, and a substrate 315. The magnet 311 is cylindrical. The magnet 311 is, for example, a multipole magnet with 16 or 24 poles. The magnet 311 rotates together with the steering shaft 102.

[0101] Each magnetic yoke 312, 313 is a component of a magnetic body used to form a magnetic circuit. Multiple protrusions are provided in the cylindrical portion of each magnetic yoke 312, 313. Each magnetic yoke 312, 313 is assembled in such a way that a magnet 311 passes through the hollow portion of the cylindrical portion and the protrusions engage.

[0102] The torsion bar 314 is a component that twists as the steering shaft 102 rotates. The torsion bar 314 passes through the hollow part of the magnet 311 and is fixed at both ends to the steering shaft 102.

[0103] Electronic components such as a magnetic flux detection unit 216 are mounted on the substrate 315. The magnetic flux detection unit 216 is arranged facing the side of the magnet 311. The magnetic flux detection unit 216 detects the magnetic balance of each yoke 312, 313, which changes according to the torsion of the torsion bar 314, as a change in magnetic flux received from the magnet 311. As a result, the magnetic flux detection unit 216 obtains the first rotation angle of the steering shaft 102. In addition, a dedicated element for detecting magnetic balance can also be mounted on the substrate 315.

[0104] The calculation unit 250 calculates the rudder angle of the steering shaft 102 based on the difference angle between the first rotation angle of the magnetic flux detection unit 216 constituting the torque sensor 310 and the second rotation angle of the rotation angle sensor 230.

[0105] Based on the above configuration, the rotation angle of the steering shaft 102 can be detected using the magnet 311 of the torque sensor 310. Therefore, as the rudder angle sensor 210, components such as the drive gear 213 are not required. Thus, significant miniaturization and cost reduction of the rudder angle sensor 210 can be expected. Since no gear components are used when detecting the angle of the steering shaft 102, improved angle detection accuracy can be anticipated.

[0106] Furthermore, since the magnet 311 of the torque sensor 310 is a multipole magnet, the rudder angle detection range can be expanded as described above. Of course, similar to the third embodiment, the range of rudder angle that can be detected can also be expanded by considering the virtual gear ratio N.

[0107] This application is not limited to the above-described embodiments. Various modifications can be made without departing from the spirit of this application, as follows.

[0108] For example, the rudder angle detection method shown in the above embodiments is one example. Alternatively, the following method can be used: instead of making a one-to-one correspondence between the difference angle and the rudder angle, the number of times the driving gear 213, driven gear 214, or motor 330 rotates is calculated based on the difference angle, and the rudder angle is calculated based on the absolute angle calculated from the rotational speed.

[0109] In addition, the first reduction ratio Z EPS Second reduction ratio Z angle , rudder angle range θ, number of pole pairs P angle The virtual gear ratio N is an example. Of course, other values ​​can also be used.

[0110] This application has been described based on embodiments, but it should be understood that this application is not limited to these embodiments or structures. This application includes various modifications and equivalent variations. In addition, various combinations and methods, including only one element, or other combinations and methods above or below, also fall within the scope and spirit of this application.

Claims

1. A rotation angle detection device, characterized in that, Include: The first detection unit detects the first rotation angle of the steering shaft, which rotates in conjunction with the steering wheel; The second detection unit detects the second rotation angle of the motor shaft connected to the steering shaft via the reduction mechanism; as well as The calculation unit receives the first rotation angle from the first detection unit and the second rotation angle from the second detection unit, and calculates the rudder angle of the steering shaft based on the difference angle between the first rotation angle and the second rotation angle. The first detection unit has: The drive gear rotates in conjunction with the steering shaft; The driven gear meshes with the driving gear and rotates in conjunction with the driving gear; A magnet is fixed to the driven gear and rotates together with the driven gear; as well as The magnetic flux detection unit detects the first rotation angle of the steering shaft based on the change in magnetic flux received from the magnet. If the first reduction ratio of the reduction mechanism between the steering shaft and the motor shaft is defined as Z... EPS The second reduction ratio between the driving gear and the driven gear is defined as Z. angle The range of the rudder angle obtained by the calculation unit is defined as θ. Then the first reduction ratio Z EPS The second reduction ratio Z angle And the angular range θ of the rudder angle is set to satisfy |(Z EPS -WITH angle )×θ|<360° or, |(Z EPS -WITH angle )×θ|<180° conditions.

2. A rotation angle detection device, characterized in that, Include: The first detection unit detects the first rotation angle of the steering shaft, which rotates in conjunction with the steering wheel; The second detection unit detects the second rotation angle of the motor shaft connected to the steering shaft via the reduction mechanism; as well as The calculation unit receives the first rotation angle from the first detection unit and the second rotation angle from the second detection unit, and calculates the rudder angle of the steering shaft based on the difference angle between the first rotation angle and the second rotation angle. The first detection unit has: The drive gear rotates in conjunction with the steering shaft; The driven gear meshes with the driving gear and rotates in conjunction with the driving gear; A magnet is fixed to the driven gear and rotates together with the driven gear; as well as The magnetic flux detection unit detects the first rotation angle of the steering shaft based on the change in magnetic flux received from the magnet. If the first reduction ratio of the reduction mechanism between the steering shaft and the motor shaft is defined as Z... EPS The second reduction ratio between the driving gear and the driven gear is defined as Z. angle The virtual gear ratio that makes the second reduction ratio an integer multiple is defined as N, and the angular range of the rudder angle obtained by the calculation unit is defined as θ. Then the first reduction ratio Z EPS The second reduction ratio Z angle The virtual gear ratio N and the rudder angle range θ are set to satisfy... |(Z EPS -WITH angle ×N)×θ|<360° or, |(Z EPS -WITH angle ×N)×θ|<180° conditions.

3. A rotation angle detection device, characterized in that, Include: The first detection unit detects the first rotation angle of the steering shaft, which rotates in conjunction with the steering wheel; The second detection unit detects the second rotation angle of the motor shaft connected to the steering shaft via the reduction mechanism; as well as The calculation unit receives the first rotation angle from the first detection unit and the second rotation angle from the second detection unit, and calculates the rudder angle of the steering shaft based on the difference angle between the first rotation angle and the second rotation angle. The first detection unit has: The drive gear rotates in conjunction with the steering shaft; The driven gear meshes with the driving gear and rotates in conjunction with the driving gear; A magnet is fixed to the driven gear and rotates together with the driven gear; as well as The magnetic flux detection unit detects the first rotation angle of the steering shaft based on the change in magnetic flux received from the magnet. The magnet generates multiple cycles of magnetic flux change during one revolution of the driven gear. If the first reduction ratio of the reduction mechanism between the steering shaft and the motor shaft is defined as Z... EPS The second reduction ratio between the driving gear and the driven gear is defined as Z. angle The number of pole pairs of the magnet is defined as P. angle The range of the rudder angle obtained by the calculation unit is defined as θ. Then the first reduction ratio Z EPS The second reduction ratio Z angle The pole pair number P angle And the angular range θ of the rudder angle is set to satisfy |(Z EPS -WITH angle ×P angle )×θ|<360° or, |(Z EPS -WITH angle ×P angle )×θ|<180° conditions.

4. A rotation angle detection device, characterized in that, Include: The first detection unit detects the first rotation angle of the steering shaft, which rotates in conjunction with the steering wheel; The second detection unit detects the second rotation angle of the motor shaft connected to the steering shaft via the reduction mechanism; as well as The calculation unit receives the first rotation angle from the first detection unit and the second rotation angle from the second detection unit, and calculates the rudder angle of the steering shaft based on the difference angle between the first rotation angle and the second rotation angle. The first detection unit has: The drive gear rotates in conjunction with the steering shaft; The driven gear meshes with the driving gear and rotates in conjunction with the driving gear; A magnet is fixed to the driven gear and rotates together with the driven gear; as well as The magnetic flux detection unit detects the first rotation angle of the steering shaft based on the change in magnetic flux received from the magnet. The magnet generates multiple cycles of magnetic flux change during one revolution of the driven gear. If the first reduction ratio of the reduction mechanism between the steering shaft and the motor shaft is defined as Z... EPS The second reduction ratio between the driving gear and the driven gear is defined as Z. angle The number of pole pairs of the magnet is defined as P. angle The virtual gear ratio that makes the second reduction ratio an integer multiple is defined as N, and the angular range of the rudder angle obtained by the calculation unit is defined as θ. Then the first reduction ratio Z EPS The second reduction ratio Z angle The pole pair number P angle The virtual gear ratio N and the rudder angle range θ are set to satisfy... |(Z EPS -WITH angle ×P angle ×N)×θ|<360° or, |(Z EPS -WITH angle ×P angle ×N)×θ|<180° conditions.

5. The rotation angle detection device as described in any one of claims 1 to 4, characterized in that, The steering shaft has a torque sensor for detecting the rotational torque of the steering shaft. The torque sensor has a magnet that rotates together with the steering shaft.

6. The rotation angle detection device as described in any one of claims 1 to 4, characterized in that, The calculation unit has an angle correction unit that makes the angle period of the first rotation angle an integer multiple.

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