Steering device

Abstract

A steering device 1 comprises: a steering shaft 20 that steers steered wheels 101, 102 of a vehicle; a ball screw nut 31 that is threadedly engaged with a ball screw groove 201 formed in the steering shaft 20 via a plurality of balls 33; a driven-side toothed pulley 42 that rotates integrally with the ball screw nut 31; a drive-side toothed pulley 41 that has a smaller diameter than the driven-side toothed pulley 42; a drive motor 29 that rotationally drives the drive-side toothed pulley 41; a toothed belt 43 that is wound around the driven-side toothed pulley 42 and the drive-side toothed pulley 41; and a first sensor 51 and a second sensor 52 that detect tooth skipping of the toothed belt 43 with respect to the drive-side toothed pulley 41. The drive-side toothed pulley 41 and the driven-side toothed pulley 42 have external teeth 410 and 420 engaged with the toothed belt 43. The first sensor 51 and the second sensor 52 detect the tooth skipping by displacement of the toothed belt 43 in a radial direction of the drive-side toothed pulley caused by internal teeth 430 of the toothed belt 43 riding onto the external teeth 410 of the drive-side toothed pulley 41.

Description

Steering apparatus

[0001] The present invention relates to a steering apparatus for vehicles.

[0002] Conventionally, there is a steering apparatus in which the power of a drive motor is transmitted to a ball screw nut by a belt transmission mechanism, and the turning shaft is axially moved by rotation of the ball screw nut to steer the steered wheels, wherein the steering apparatus is capable of detecting the occurrence of tooth jumping of a toothed belt in the belt transmission mechanism. The applicant of the present application proposes the steering apparatus described in Patent Document 1 as such a steering apparatus.

[0003] The steering apparatus described in Patent Document 1 includes: a ball nut screwed to a turning shaft; a drive-side toothed pulley that rotates integrally with a drive motor; a driven-side toothed pulley that rotates integrally with the ball nut; a toothed belt wound around the drive-side toothed pulley and the driven-side toothed pulley; and a control device. In order to obtain the rotation angle of the drive-side toothed pulley, the drive motor is provided with a rotation angle sensor that detects the rotation angle of the output shaft of the drive motor, and in order to obtain the rotation angle of the driven-side toothed pulley, the driven-side toothed pulley is provided with a rotation angle sensor that detects the rotation angle of the driven-side toothed pulley. The control device detects tooth jumping of the toothed belt by comparing the rotation angle of the drive-side toothed pulley with a converted value obtained by converting the rotation angle of the driven-side toothed pulley into the rotation angle of the drive-side toothed pulley.

[0004] Japanese Unexamined Patent Application Publication No. 2021-109494

[0005] The steering device described in Patent Document 1 includes a mechanism for detecting tooth skipping by detecting the difference between the rotation angle of the drive-side toothed pulley and the rotation angle of the driven-side toothed pulley, which is caused by tooth skipping in the toothed belt. However, in this steering device, both the drive-side toothed pulley and the driven-side toothed pulley rotate more than 360° many times, so even if tooth skipping occurs and a tooth of the toothed belt goes past one tooth of the drive-side toothed pulley, the distance of the distance of the distance of the toothed belt is small compared to the total distance traveled by the toothed belt, making it difficult to detect tooth skipping. Furthermore, the distance between the teeth of the toothed belt expands and contracts due to expansion and contraction of the toothed belt or changes in the tension of the toothed belt. Since the distance of skipping a tooth is small, it is difficult to distinguish whether it is the distance of tooth skipping or the distance of expansion and contraction, and it is not easy to determine whether tooth skipping has occurred. Therefore, the object of the present invention is to provide a steering device capable of detecting tooth skipping in a toothed belt.

[0006] To achieve the above objective, the present invention provides a steering device comprising: a steering shaft for steering the steering wheels of a vehicle; a ball screw nut that is screwed into a ball screw groove formed on the steering shaft via a plurality of balls; a driven toothed pulley that rotates integrally with the ball screw nut; a drive toothed pulley having a smaller diameter than the driven toothed pulley; a drive motor for rotationally driving the drive toothed pulley; a toothed belt wrapped around the driven toothed pulley and the drive toothed pulley; and a sensor for detecting tooth skipping of the toothed belt relative to the drive toothed pulley, wherein the drive toothed pulley and the driven toothed pulley have external teeth that mesh with the toothed belt, and the sensor detects the tooth skipping by the radial displacement of the toothed belt relative to the drive toothed pulley.

[0007] According to the present invention, it becomes possible to easily detect tooth skipping in a toothed belt.

[0008] Figure 1 is a schematic diagram showing an example of the configuration of a steer-by-wire steering device according to an embodiment of the present invention. Figure 2 is an enlarged view showing a part of Figure 1. Figure 3 is a configuration diagram showing the drive-side toothed pulley, driven-side toothed pulley, and toothed belt of the belt transmission mechanism together with the steering shaft, housing, and ball screw nut. Figure 4A is an explanatory diagram showing an example of the state of the drive-side toothed pulley and its surrounding area just before tooth skipping occurs due to hitting the right end. Figure 4B is an explanatory diagram showing an example of the state of the drive-side toothed pulley and its surrounding area when tooth skipping is occurring due to hitting the right end. Figure 4C is an explanatory diagram showing the state after tooth skipping has occurred. Figure 5A is an explanatory diagram showing an example of the state of the drive-side toothed pulley and its surrounding area just before tooth skipping occurs due to hitting the left end. Figure 5B is an explanatory diagram showing an example of the state of the drive-side toothed pulley and its surrounding area when tooth skipping is occurring due to hitting the left end. Figure 5C is an explanatory diagram showing the state after tooth skipping has occurred. The graph disclosed in Figure 6 shows an example of the change in magnetic field strength detected by the first sensor when tooth skipping occurs near the right edge.

[0009] [Embodiments] Embodiments of the present invention will be described with reference to the drawings. The embodiments shown below are presented as preferred specific examples for carrying out the present invention, and some parts specifically illustrate various technically preferable technical matters, but the technical scope of the present invention is not limited to these specific embodiments.

[0010] Figure 1 is a schematic diagram showing an example of the configuration of a steer-by-wire steering device 1 according to an embodiment of the present invention. Figure 2 is an enlarged view showing a part of Figure 1. Figure 1 shows the steering device 1 as viewed from the front of the vehicle, with the left side of the drawing corresponding to the right side of the vehicle and the right side of the drawing corresponding to the left side of the vehicle. Hereinafter, "left" and "right" refer to the left and right sides of the vehicle in the vehicle width direction, respectively.

[0011] The steering system 1 comprises a control device 10, a steering wheel 11 rotated by the driver of the vehicle, a steering reaction force applying device 12 that applies steering reaction force to the steering wheel 11, a steering angle sensor 13 that detects the steering angle, which is the rotation angle of the steering wheel 11, and a steering device 2 that steers the vehicle's steering wheels 101 and 102.

[0012] The steering device 2 comprises a steering shaft 20 extending in the vehicle width direction, a cylindrical housing 21 housing the steering shaft 20, a pinion shaft 22 that meshes with rack teeth 200 provided on the steering shaft 20, inner ball joints 23 and 24 attached to both ends of the steering shaft 20, end dampers 25 and 26 and bellows 27 and 28 with a bellows structure attached to both ends of the housing 21, a drive motor 29 controlled by a control device 10, a ball screw mechanism 3 that moves the steering shaft 20 axially by the rotation of the drive motor 29, and a belt transmission mechanism 4 that transmits the rotation of the drive motor 29 to the ball screw mechanism 3.

[0013] The housing 21 is fixed to the vehicle body. The housing 21 is composed of a first housing member 211 and a second housing member 212. The steering shaft 20 steers the steering wheels 101 and 102 by moving in the vehicle width direction relative to the housing 21. The pinion shaft 22 is rotatably supported relative to the housing 21 by a bearing 220. The steering shaft 20 is pressed toward the pinion shaft 22 by a rack guide mechanism (not shown) provided in the housing 21. The pinion shaft 22, together with the ball screw mechanism 3, supports the steering shaft 20 inside the housing 21. The pinion shaft 22 also prevents the steering shaft 20 from rotating relative to the housing 21.

[0014] The inner ball joints 23 and 24 each have tie rods 231 and 241 and ball joint sockets 232 and 242, respectively. The ends of the tie rods 231 and 241 are ball portions 231a and 241a. The ball portions 231a and 241a are pivotably housed in the ball joint sockets 232 and 242. The ball joint sockets 232 and 242 are formed to be larger in diameter than the steering shaft 20. The ball joint sockets 232 and 242 are fixed to both ends of the steering shaft 20. The bellows 27 and 28 have one end fixed to the outer circumference of the housing 21 and the other end fixed to the outer circumference of the tie rods 231 and 241.

[0015] As shown in Figure 2, the ball screw mechanism 3 includes a ball screw nut 31 through which the steering shaft 20 is inserted in the center, a bearing 32 that rotatably supports the ball screw nut 31 relative to the housing 21, and a plurality of balls 33. The ball screw nut 31 is screwed into a ball screw groove 201 formed in the steering shaft 20 via the plurality of balls 33. The plurality of balls 33 roll in the ball screw groove 201 of the steering shaft 20 and the ball screw groove 311 of the ball screw nut 31, and circulate by passing through a circulation path 312 formed in the ball screw nut 31. Since the axial direction of the steering shaft 20 is along the vehicle width direction, when the ball screw nut 31 rotates, the steering shaft 20 moves along the vehicle width direction. As the steering shaft 20 moves in the vehicle width direction, the steering wheels 101 and 102 are steered via the inner ball joints 23 and 24.

[0016] Movement of the steering shaft 20 toward the left side of the vehicle is restricted by the ball joint socket 232 of the right inner ball joint 23 contacting the end damper 25 attached to the right end of the housing 21. Movement of the steering shaft 20 toward the right side of the vehicle is restricted by the ball joint socket 242 of the left inner ball joint 24 contacting the end damper 26 attached to the left end of the housing 21.

[0017] Hereinafter, when the ball joint socket 232 of the right inner ball joint 23 contacts the end damper 25, this is referred to as a right end contact, and when the ball joint socket 242 of the left inner ball joint 24 contacts the end damper 26, this is referred to as a left end contact. A right end contact occurs when the steering shaft 20 reaches the one end contact position, which is one end of its range of motion, and a left end contact occurs when the steering shaft 20 reaches the other end contact position, which is the other end of its range of motion.

[0018] The drive motor 29 includes a motor body 291 fixed to the housing 21, an output rotating shaft 292 that rotates relative to the motor body 291, and a rotation angle detector 293 that detects the rotation angle of the output rotating shaft 292 relative to the motor body 291. The control device 10 controls the drive motor 29 based on the steering angle detected by the steering angle sensor 13, etc., to steer the steering wheels 101 and 102. At this time, the control device 10 controls the drive motor 29 so that the rotation angle of the output rotating shaft 292 detected by the rotation angle detector 293 is an angle corresponding to the steering angle. The rotation angle detector 293 is configured, for example, by a multi-turn encoder and is capable of uniquely detecting the rotation angle of the output rotating shaft 292 over the entire range of motion of the steering shaft 20.

[0019] The belt transmission mechanism 4 includes a drive-side toothed pulley 41 fixed to the output rotating shaft 292 of the drive motor 29, a driven-side toothed pulley 42 fixed to a ball screw nut 31 and rotating integrally with the ball screw nut 31, and a toothed belt 43 wrapped around the drive-side toothed pulley 41 and the driven-side toothed pulley 42. The drive-side toothed pulley 41 has a smaller diameter than the driven-side toothed pulley 42. The drive motor 29 rotates the drive-side toothed pulley 41. The rotation of the output rotating shaft 292 is reduced by the toothed belt 43 and transmitted to the driven-side toothed pulley 42.

[0020] Figure 3 is a configuration diagram showing the drive-side toothed pulley 41, the driven-side toothed pulley 42, and the toothed belt 43 of the belt transmission mechanism 4 together with the steering shaft 20, the first housing member 211 of the housing 21, and the ball screw nut 31. In this embodiment, the steering device 1 is equipped with a first sensor 51 and a second sensor 52 for detecting tooth skipping of the toothed belt 43 relative to the drive-side toothed pulley 41. The first sensor 51 and the second sensor 52 are inserted through insertion holes 210 formed in the first housing member 211 and attached to the first housing member 211.

[0021] The drive-side toothed pulley 41 has a plurality of external teeth 410 that mesh with the toothed belt 43. The driven-side toothed pulley 42 has a plurality of external teeth 420 that mesh with the toothed belt 43. The toothed belt 43 has a plurality of internal teeth 430 that mesh with the plurality of external teeth 410, 420 of the drive-side toothed pulley 41 and the driven-side toothed pulley 42. The toothed belt 43 is made of rubber (including elastomer), and is composed of a rubber composition in which the rubber component of an unvulcanized rubber composition containing various rubber compounding agents is vulcanized by the heat and pressure during belt molding.

[0022] The toothed belt 43 has a magnetized portion where at least a part of its entire circumference is magnetized. The first magnetized portion 431 and the second magnetized portion 432 of the toothed belt 43 in this embodiment, shown by cross-hatching in Figure 3, contain a magnetized ferromagnetic material (are magnetized). The first magnetized portion 431 and the second magnetized portion 432 are formed, for example, by mixing ferromagnetic powder into the rubber composition constituting the toothed belt 43 and then magnetizing the ferromagnetic powder after the toothed belt 43 is molded. Alternatively, the first magnetized portion 431 and the second magnetized portion 432 may be formed by attaching a magnetic sheet containing a magnetized ferromagnetic material or by embedding a magnet.

[0023] The first sensor 51 and the second sensor 52 are positioned opposite the outer circumferential surface 43a of the toothed belt 43 at the end of two span portions 433 and 434 on the drive-side toothed pulley 41 of the toothed belt 43, which are straight portions of the toothed belt 43 that do not overlap the drive-side toothed pulley 41 and the driven-side toothed pulley 42. In this embodiment, the first sensor 51 and the second sensor 52 are magnetic sensors that detect changes in the strength of the magnetic field due to the approach of the first magnetized portion 431 and the second magnetized portion 432, respectively, of the toothed belt 43. Signals indicating the detection results of the first sensor 51 and the second sensor 52 are sent to the control device 10. For example, general-purpose magnetic sensors used to detect wheel speed by changes in the magnetic field of a magnetic encoder attached to the hub ring of a hub unit that supports a wheel are used as the first sensor 51 and the second sensor 52.

[0024] When the steering shaft 20 is in the neutral position, the first magnetized portion 431 and the second magnetized portion 432 are at the same distance from the drive-side toothed pulley 41. When the drive-side toothed pulley 41 shown in Figure 3 rotates clockwise from the neutral position and the toothed belt 43 has made approximately three rotations, the steering shaft 20 reaches the one-side end contact position, which is one end of the range of motion, and the first magnetized portion 431 is located at the position where the drive-side toothed pulley 41 and the toothed belt 43 begin to mesh, which is the position on the left side of Figure 3. The first magnetized portion 431 is provided on the portion of the toothed belt 43 facing the first sensor 51 when the steering shaft 20 reaches the one-side end contact position, which is one end of the range of motion, and the right end contact occurs. Furthermore, when the drive-side toothed pulley 41 shown in Figure 3 rotates counterclockwise from the neutral position and the toothed belt 43 has made approximately three rotations, the steering shaft 20 reaches the other end contact position, which is the other end of the movable range, and the second magnetization portion 432 is located at the position on the right in Figure 3, where the drive-side toothed pulley 41 and the toothed belt 43 begin to mesh. The second magnetization portion 432 is provided on the portion of the toothed belt 43 that faces the second sensor 52 when the steering shaft 20 reaches the other end contact position, which is the other end of the movable range, and left end contact occurs.

[0025] The first sensor 51 and the second sensor 52 detect tooth skipping by the radial displacement of the toothed belt 43 of the drive-side toothed pulley 41 caused by the internal teeth 430 of the toothed belt 43 riding up onto the external teeth 410 of the drive-side toothed pulley 41. The first sensor 51 and the second sensor 52 are each located radially outside the drive-side toothed pulley 41 with respect to the position where the drive-side toothed pulley 41 and the toothed belt 43 begin to mesh. Next, the method for detecting tooth skipping by the first sensor 51 and the second sensor 52 will be described in detail.

[0026] Figures 4A, 4B, and 4C are explanatory diagrams showing an example of the state of the drive-side toothed pulley 41 and its surrounding area when tooth skipping occurs due to contact with the right end. Figure 4A shows the state immediately before contact with the right end occurs, Figure 4B shows the state when tooth skipping is in progress, and Figure 4C shows the state after tooth skipping has occurred. In Figures 4A, 4B, and 4C, one of the multiple external teeth 410 of the drive-side toothed pulley 41 is marked with a black circle, and the rotation direction of the drive-side toothed pulley 41 when contact with the right end occurs is indicated by arrow A. １ This is shown.

[0027] When the right end is hit, the movement of the steering shaft 20 stops, and consequently, the rotation of the driven toothed pulley 42 also stops. On the other hand, the drive toothed pulley 41 tries to continue rotating due to the rotational inertia of the drive motor 29, so the external teeth 410 of the drive toothed pulley 41 push the internal teeth 430 of the toothed belt 43 radially outward from the drive toothed pulley 41. The toothed belt 43 rides up onto the external teeth 410 of the drive toothed pulley 41 and is displaced radially outward from the drive toothed pulley 41. As shown in Figure 4B, the first magnetized portion 431 is displaced radially from the drive toothed pulley 41 and approaches the first sensor 51. The first sensor 51 detects the change in magnetic field strength due to the first magnetized portion 431 of the toothed belt 43 approaching the first sensor 51. The control device 10 detects the occurrence of tooth skipping based on the detection signal from the first sensor 51. Tooth skipping is more likely to occur in the small-diameter drive-side toothed pulley 41, which has fewer teeth than the driven-side toothed pulley 42, and therefore fewer teeth that mesh between the internal teeth 430 of the toothed belt 43 and the external teeth 410 of the drive-side toothed pulley 41.

[0028] Figures 5A, 5B, and 5C are explanatory diagrams showing an example of the state of the drive-side toothed pulley 41 and its surrounding area when tooth skipping occurs due to contact with the left end. Figure 5A shows the state immediately before contact with the left end occurs, Figure 5B shows the state when tooth skipping is in progress, and Figure 5C shows the state after tooth skipping has occurred. In Figures 5A, 5B, and 5C, as in Figures 4A, 4B, and 4C, one of the multiple external teeth 410 of the drive-side toothed pulley 41 is marked with a black circle, and the rotation direction of the drive-side toothed pulley 41 when contact with the left end occurs is indicated by arrow A. ２ This is shown.

[0029] When a left-end contact occurs, the external teeth 410 of the drive-side toothed pulley 41 push the internal teeth 430 of the toothed belt 43 radially outward from the drive-side toothed pulley 41, similar to when a right-end contact occurs. The toothed belt 43 rides up onto the external teeth 410 of the drive-side toothed pulley 41 and is displaced radially outward from the drive-side toothed pulley 41. The second magnetized portion 432 is displaced radially from the drive-side toothed pulley 41 and approaches the second sensor 52. The second sensor 52 detects the change in magnetic field strength caused by the second magnetized portion 432 of the toothed belt 43 approaching the second sensor 52. The control device 10 detects the occurrence of tooth skipping based on the detection signal from the second sensor 52.

[0030] Figure 6 is a graph showing an example of the change in magnetic field strength detected by the first sensor 51 when tooth skipping occurs near the right end. The horizontal axis of the graph is the time axis, and the vertical axis is the magnetic field strength (magnetic flux density). As shown in Figure 6, when the first magnetization part 431 is displaced radially in the drive-side toothed pulley 41 and approaches the first sensor 51, the magnetic field strength detected by the first sensor 51 temporarily increases, and then returns to its original value. The control device 10 can detect the occurrence of tooth skipping by this change in magnetic field strength. Similarly, when tooth skipping occurs near the left end, the second magnetization part 432 is displaced radially in the drive-side toothed pulley 41 and approaches the second sensor 52, causing a change in the magnetic field strength detected by the second sensor 52. The control device 10 can detect the occurrence of tooth skipping by this change in magnetic field strength.

[0031] When the control device 10 detects the occurrence of tooth skipping, it notifies the driver that the toothed belt 43 should be replaced, for example, by displaying a message on the vehicle's instrument panel. This is because, when tooth skipping occurs, the actual neutral position of the steering shaft 20 (the position of the steering shaft 20 when the vehicle is moving straight) and the neutral position recognized by the control device 10 based on the detected value of the rotation angle detector 293 of the drive motor 29 become misaligned, making it undesirable to continue driving the vehicle in this condition. In this case, although the driver can operate the vehicle by manipulating the steering wheel 11 according to the direction of travel and surrounding road conditions, tooth skipping is more likely to occur when the toothed belt 43 deteriorates. Therefore, if tooth skipping occurs, the toothed belt 43 should be replaced promptly before further deterioration occurs.

[0032] Depending on the conditions around the right or left end, tooth skipping may occur not only for one tooth, but for two or more teeth in succession. The control device 10 can count the number of tooth skips by the number of increases in magnetic field strength detected by the first sensor 51 or the second sensor 52 (the number of peaks in the graph in Figure 6). Furthermore, when tooth skipping occurs, the control device 10 may notify the driver and correct the position of the steering shaft 20 obtained from the rotation angle detector 293 of the drive motor 29 according to the number of tooth skips that have occurred, and control the drive motor 29. When control is performed in this manner, even after tooth skipping occurs, it is possible to drive the vehicle straight when the steering wheel 11 is in the neutral position.

[0033] (Effects of the Embodiment) According to the embodiment described above, by detecting the displacement of the toothed belt 43 radially outward of the drive-side toothed pulley 41 by the first sensor 51 or the second sensor 52, it becomes possible to detect the occurrence of tooth skipping.

[0034] In the above embodiment, only a portion of the toothed belt 43's circumference (the first magnetized portion 431 and the second magnetized portion 432) is magnetized. However, the present invention is not limited to this, and the toothed belt 43 may be magnetized over its entire circumference. In this case as well, the first sensor 51 or the second sensor 52 can detect the displacement of the toothed belt 43 radially outward of the drive-side toothed pulley 41. Furthermore, although the above embodiment described the case where the first sensor 51 or the second sensor 52 is a magnetic sensor, the present invention may use, for example, an optical, capacitive, or inductive proximity sensor as the first sensor 51 or the second sensor 52, as long as it is possible to detect the approach caused by the toothed belt 43 lifting up. When using a capacitive or inductive proximity sensor, for example, the toothed belt 43 may be constructed from conductive rubber.

[0035] (Note) The present invention has been described above based on embodiments, but these embodiments do not limit the invention as claimed. Furthermore, it should be noted that not all combinations of features described in the embodiments are necessarily essential for solving the problem of the invention.

[0036] Furthermore, the present invention can be implemented by omitting some components, or by adding or substituting components, without departing from its spirit. For example, the above embodiment applies the present invention to a steer-by-wire type steering system 1 in which the steering wheel 11 and the steering device 2 are not mechanically connected. However, the present invention is not limited to this, and may also be applied to an electric power steering system in which the steering wheel 11 and the steering device 2 are mechanically connected by a steering shaft. In this case, the output torque of the drive motor 29 is applied to the steering shaft 20 as a steering assist force by the belt transmission mechanism 4 and the ball screw mechanism 3.

[0037] 1...Steering device 20...Steering shaft 29...Drive motor 31...Ball screw nut 41...Drive side toothed pulley 410...External teeth 42...Driven side toothed pulley 420...External teeth 43...Toothed belt 430...Internal teeth 431...First magnetization part 432...Second magnetization part 433, 434...Spanning part 43a...Outer surface 51...First sensor 52...Second sensor

Claims

1. A steering device comprising: a steering shaft for steering the steering wheels of a vehicle; a ball screw nut screwed into a ball screw groove formed on the steering shaft via a plurality of balls; a driven toothed pulley that rotates integrally with the ball screw nut; a drive toothed pulley having a smaller diameter than the driven toothed pulley; a drive motor for rotationally driving the drive toothed pulley; a toothed belt wrapped around the driven toothed pulley and the drive toothed pulley; and a sensor for detecting tooth skipping of the toothed belt relative to the drive toothed pulley, wherein the drive toothed pulley and the driven toothed pulley have external teeth that mesh with the toothed belt, and the sensor detects the tooth skipping by the radial displacement of the toothed belt relative to the drive toothed pulley.

2. The steering device according to claim 1, wherein the toothed belt has a magnetized portion in which at least a part of its entire circumference is magnetized, and the sensor detects a change in the strength of the magnetic field caused by the magnetized portion of the toothed belt approaching the sensor.

3. The steering device according to claim 1 or 2, wherein the two sensors are arranged facing the outer circumferential surface of the end on the drive-side toothed pulley side of two span portions of the toothed belt that do not engage with the driven-side toothed pulley and the drive-side toothed pulley.

4. The steering device according to claim 2, wherein the toothed belt has a magnetized portion in which at least the portion facing the two sensors when the steering shaft reaches the end-contact position which is the end of its range of motion is the magnetized portion of the entire circumference.

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