JP2020044947A - Steering device - Google Patents

Abstract

To provide a steering device capable of reducing an influence of a steering angle sensor magnet onto a torque sensor at a neutral position of a turning shaft.SOLUTION: A first gear magnet 43 and a second gear magnet 44, when a turning shaft is at a neutral position, are arranged so that a first magnetic flux generated by a first N pole and a first S pole and a second magnetic flux generated by a second N pole and a second S pole face each other in the same direction in a region between the first gear magnet and the second gear magnet on a plane at right angles to a rotational axis of a steering shaft. On a plane at right angles to the rotational axis of the steering shaft, there is provided a shield plate 55 overlapping a first gear magnetic sensor and a second gear magnetic sensor. The first gear magnetic sensor detects a rotational angle of a first gear on the basis of a change in a magnetic field of the first gear magnet and the second gear magnetic sensor detects a rotational angle of a second gear on the basis of a change in a magnetic field of the second gear magnet.SELECTED DRAWING: Figure 8

Description

  The present invention relates to a steering device equipped with a steering angle sensor and a torque sensor.

  Patent Literature 1 includes a steering absolute angle sensor (steering angle sensor) that detects a steering angle of a steering wheel, and a torque sensor that detects a steering torque input to the steering wheel, based on a detection result by these sensors. An electric power steering device that assists the steering force of a steering wheel by using a steering wheel is disclosed. In Patent Document 1, a shield plate having a magnetic path resistance larger than an air gap is provided between a torque sensor and a steering absolute angle sensor so that the influence of a magnetic field generated by the steering absolute angle sensor on the torque sensor is reduced. ing.

JP 2014-31145 A

  By the way, in such a steering device, for example, a pair of cylindrical portions of a yoke are arranged in the radial direction on the outer periphery of a cylindrical multipolar magnet fixed to an input shaft, and a Hall IC is mounted therebetween. . A gear for transmitting rotation is installed on the input shaft, a magnet for a steering angle sensor (steering angle sensor magnet) is mounted on the gear, and a GMR (Giant Magneto Resistive effect) sensor is mounted on the upper side and a shield is provided on the lower side. A magnetic plate is mounted.

  However, in the above configuration, since the steering angle sensor magnet exists near the Hall IC, the yoke, and the magnetic flux collection ring, there is a possibility that the fluctuation of the magnetic field due to the rotation of the magnet affects the Hall IC for the torque sensor. There is a problem that there is.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a steering device that can reduce the influence of a steering angle sensor magnet on a torque sensor in a neutral position of a steered shaft. It is in.

  In order to solve the above-mentioned problem, in the steering device of the present invention, when the steered shaft is at the neutral position, the first gear magnet and the second gear magnet are positioned on a plane perpendicular to the rotation axis of the steering shaft. In the region between the first gear magnet and the second gear magnet, the first magnetic flux generated by the first north pole and the first south pole and the second magnetic flux generated by the second north pole and the second south pole have the same direction. A magnetic shielding member is provided so as to face the first gear magnetic sensor and the second gear magnetic sensor on a plane perpendicular to the rotation axis of the steering shaft. The first gear magnetic sensor detects the rotation angle of the first gear based on the change in the magnetic field of the first gear magnet, and the second gear magnetic sensor detects the rotation angle of the second gear based on the change in the magnetic field of the second gear magnet. Detect the rotation angle.

According to the present invention, in the region between the first gear magnetic sensor and the second gear magnetic sensor, the first magnetic flux and the second magnetic flux are oriented in the same direction, so that the magnetic field circulates smoothly. Thus, the occurrence of local saturation in the magnetic shielding member can be suppressed. Thus, even when the first gear magnet and the second gear magnet, which are the steering angle sensor magnets, are close to the first yoke or the second yoke of the torque sensor, these first and second yokes are in the first yoke. Therefore, it is possible to suppress the influence of the magnetic field of the second gear magnet on the detection accuracy of the torque sensor.
Therefore, at the neutral position of the steered shaft, the influence of the steering angle sensor magnet on the torque sensor can be reduced, and a stable torque value can be detected.

1 is a system configuration diagram of a steering device according to an embodiment of the present invention. FIG. 2 is an exploded perspective view of a steering angle sensor in the steering device shown in FIG. FIG. 3 is an enlarged perspective view showing the magnetic flux collection holder in FIG. 2. FIG. 4 is a plan view of a magnetic shielding plate in FIG. 3. FIG. 2 is a perspective view showing a part of a torque sensor in the steering device shown in FIG. FIG. 6 is a cross-sectional view of a plane orthogonal to an axis of a torsion bar in a Hall IC portion in FIG. 5, and a schematic view of an arrangement of first, second yokes, first and second magnetic flux collecting rings, and a Hall IC. FIG. 6 is a diagram for explaining magnetization when the steered shaft is neutral and torque is generated in FIG. 5. It is a figure for explaining arrangement of a steering angle sensor magnet in the present invention. It is a figure for explaining a positional relationship of a magnetic shielding board and a yoke. It is a figure for explaining a physical relationship of a magnetic shielding board and a steering angle sensor magnet. It is a figure for explaining the magnetization direction of a steering angle sensor magnet. FIG. 9 is a waveform diagram showing a relationship between the angle of the magnet and the amount of torque fluctuation when the first and second gear magnets are magnetized in opposite directions. FIG. 8 is a waveform diagram showing a relationship between the angle of the magnet and the amount of torque fluctuation when the first and second gear magnets are magnetized in the same direction. It is a figure which shows the magnetic simulation result of the distribution of the magnetic flux density of the same direction as the direction from which the magnetization direction of a 1st, 2nd gear magnet differs when a rack bar is neutral. FIG. 15 is a diagram illustrating a magnetic simulation result of a magnetic flux density distribution when the directions of magnetization of the first and second gear magnets in FIG. 14 are each rotated by 90 °.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows a system configuration example of a steering device according to an embodiment of the present invention. The steering device 11 includes a steering mechanism 12 for performing steering based on an operation by a driver, and a steering assist mechanism 13 for assisting the steering operation of the driver.

  The steering mechanism 12 includes a steering shaft (steering shaft) 15 linked to a steering wheel 14, and a rack bar (steering shaft) 18 linked to tires (steered wheels) 16 and 17. The rack bar 18 is linked via a rack and pinion mechanism 19.

  The steering shaft 15 includes an input shaft (input shaft) 20 as a first shaft member that rotates integrally with the steering wheel 14, and an output shaft (output shaft) 21 as a second shaft member linked to the rack bar 18. They are connected by a torsion bar 22 (see FIG. 5). The input shaft 20 has one end in the axial direction connected to the steering wheel 14 and the other end connected to the torsion bar 22. The output shaft 21 has one end in the axial direction connected to the torsion bar 22 and the other end linked to the rack bar 18.

  Then, the pinion teeth 21 a formed on the outer peripheral side of the other end of the output shaft 21 mesh with the rack teeth 18 a formed on one end side in the axial direction (longitudinal direction) of the rack bar 18, so that the rotational movement of the output shaft 21 is performed. Is converted into the axial movement of the rack bar 18 and transmitted.

  A steering angle sensor 23 for detecting a steering angle, which is a rotation angle of the steering shaft 15, is provided on a radially outer side (outer circumference side) of the steering shaft 15, and a steering torque applied to the steering shaft 15 by a driver's steering operation. Is integrally provided as one unit. The steering angle sensor 23 is based on a rotation angle difference between a pair of gears (a first gear 41 and a second gear 42, which will be described later) that rotate with the rotation of the steering shaft 15 (more precisely, a main gear 40, which will be described later). Detect the steering angle. The torque sensor 24 detects a steering torque based on a relative rotational displacement between the input shaft 20 and the output shaft 21.

  Tires 16 and 17 are mounted on both ends of the rack bar 18 in the axial direction via tie rods 25 and 26 and knuckle arms (not shown). Then, the rack bars 18 move in the axial direction, and the knuckle arms are pushed and pulled through the tie rods 25 and 26, whereby the directions of the tires 16 and 17 are changed.

  The steering assist mechanism 13 includes an electric motor (electric actuator) 31 that generates a steering assist force, and a control device (ECU: Electronic Control Unit) that controls driving by supplying a control current (indicated by an arrow DI) to the electric motor 31. 32, and a transmission mechanism 33 that transmits the rotation of the electric motor 31 to the rack bar 18, and assists the axial movement of the rack bar 18 with the rotation force of the electric motor 31. The control device 32 is connected to another ECU, for example, a control device for ESC (Electronic Stability Control) by a CAN (Controller Area Network) bus 34, and exchanges information by CAN communication. The electric motor 31 outputs detection results of various sensors, for example, an output signal S1 of the steering angle sensor 23 and an output signal S2 of the torque sensor 24 input to the control device 32 via the sensor harness 35, and an input signal via the CAN bus 34. The driving is controlled based on an output signal S3 of a vehicle speed sensor (not shown).

  The transmission mechanism 33 has a speed reducer that reduces the rotation of the electric motor 31 and a conversion mechanism that converts the rotation of the speed reducer into the axial movement of the rack bar 18. The speed reducer is, for example, an input pulley fixed to rotate integrally with the drive shaft of the electric motor 31, an output pulley fixed to be rotatable integrally with a nut acting as a conversion mechanism, and wound around these pulleys. It is composed of a belt or a chain as a transmission member. As the conversion mechanism, for example, a ball screw mechanism using a nut formed in a cylindrical shape so as to surround the rack bar 18 can be used. A nut-side ball screw groove is formed spirally on the inner periphery of the nut, and a spiral steering shaft-side ball screw groove is formed on the outer periphery of the rack bar 18. The nut is inserted into the rack bar 18. In this state, a ball circulation groove is formed by the nut-side ball screw groove and the steering shaft-side ball screw groove. The ball circulation groove is filled with a plurality of metal balls, and when the nut rotates, the ball moves in the ball circulation groove, whereby the rack bar 18 moves in the axial direction with respect to the nut. The rotational motion of the electric motor 31 is converted to linear motion by the ball screw mechanism, and the rack bar 18 moves in the axial direction, whereby the knuckle arm is pushed and pulled via the tie rods 25 and 26 to steer the tires 16 and 17. Power is applied.

  A worm gear having a worm shaft connected to the output shaft of the electric motor 31 so as to be integrally rotatable, and a worm wheel that meshes with the worm shaft and rotates can be used as the speed reducer. The conversion mechanism includes a pinion tooth formed on the outer peripheral side of the other end in the axial direction of the output shaft rotating integrally with the worm wheel, and a pinion tooth formed on the other end side of the rack bar 18 in the axial direction. A so-called rack and pinion mechanism composed of teeth and rack teeth that mesh with each other can also be used.

FIG. 2 is an exploded perspective view of the steering angle sensor 23 in the steering device shown in FIG. The steering angle sensor 23 includes a first gear 41 and a second gear 42, a first gear magnet 43 and a second gear magnet 44 provided on each of the gears 41 and 42, and a first gear magnet mounted on a board 45. A sensor 46 and a second gear magnetic sensor 47 are provided.
The first gear 41 has a plurality of first teeth integrally formed over the entire circumference of the first gear main body on the radially outer side of the substantially disk-shaped first gear main body with both axial ends recessed inward. Have been. The first gear 41 is rotatable with the rotation of the steering shaft 15, and the rotation axis of the first gear 41 is parallel to the rotation axis of the input shaft 20.
The number of teeth of the second gear 42 is radially outward of the substantially disk-shaped second gear main body portion in which both ends in the axial direction are depressed inward. The set plurality of second teeth are formed integrally over the entire circumference of the second gear body. The second gear 42 is rotatable with the rotation of the steering shaft 15, and the rotation axis of the second gear 42 is parallel to the rotation axis of the input shaft 20.

Then, the second gear 42 meshes with the first gear 41 and rotates with the rotation of the first gear 41. Here, the configuration in which the second gear 42 is driven by the first gear 41 is illustrated, but the present invention is not limited to this configuration. The second gear 42 meshes with the first gear 41 and may be configured to be rotationally driven by a gear different from the first gear 41 in addition to the one driven by the first gear 41.
The first gear magnet 43 is provided on the other end side of the first gear 41 in the axial direction so as to face the first mounting surface 45 a of the substrate 45. Similarly, the second gear magnet 44 is provided on the other end of the second gear 42 in the axial direction so as to face the first mounting surface 45 a of the substrate 45.

The board 45 is a well-known printed wiring board and has a first mounting surface 45a on one end side in the axial direction, and a second mounting surface 45b on the other end side, and is mounted on another ECU mounted on the vehicle. It is electrically connected via a CAN bus 34. On the substrate 45, a conductor pattern is formed on the first mounting surface 45a side, and various electronic components including the gear magnetic sensors 46 and 47 are mainly mounted on the first mounting surface 45a side. You. These various electronic components are electrically connected to a printed circuit formed by a conductor pattern on the first mounting surface 45a side by well-known reflow soldering.
Here, reflow soldering of various electronic components is illustrated as an example, but the mounting means of the electronic components is not necessarily limited to this.

  The first gear magnetic sensor 46 is a well-known GMR element, and is provided on the first mounting surface 45 a of the substrate 45 via an opening of a first gear holding unit 50 formed in the steering angle sensor holder member 48. It is mounted to face the first gear magnet 43. Accordingly, the first gear magnetic sensor 46 detects a change in the magnetic field of the first gear magnet 43 accompanying the rotation of the first gear 41, thereby detecting the first rotation angle that is the rotation angle of the first gear 41. I do.

Similarly, the second gear magnetic sensor 47 is also a GMR element, and the second gear magnetic sensor 47 is formed on the first mounting surface 45 a of the substrate 45 side by side with the first gear magnetic sensor 46 and the steering angle sensor holder member 48. It is mounted so as to face the second gear magnet 44 via the opening of the second gear holding portion 51. Thus, the second gear magnetic sensor 47 detects the second rotation angle that is the rotation angle of the second gear 42 by detecting a change in the magnetic field of the second gear magnet 44 due to the rotation of the second gear 42. I do.
The steering angle sensor 23 detects the steering wheel 14 based on the angle difference between the first rotation angle detected by the first gear magnetic sensor 46 and the second rotation angle detected by the second gear magnetic sensor 47. The rotation angle of is detected.

  The steering angle sensor holder member 48 is formed in a dish shape from a nonmagnetic material, for example, a resin material, and has a through hole through which the input shaft 20 penetrates at a substantially central position. A main gear holding portion 49 that accommodates the main gear 40 and rotatably holds the main gear 40 is provided at a peripheral portion of the through hole. Further, the steering angle sensor holder member 48 is provided with a first gear holding portion 50 which is adjacent to the main gear holding portion 49 and rotatably holds the first gear 41 in a housed state. Further, a second gear holding portion 51 that rotatably holds the second gear 42 in a housed state is provided adjacent to the first gear holding portion 50 in the steering angle sensor holder member 48. . The main gear holding portion 49, the first gear holding portion 50, and the second gear holding portion 51 are all formed to open at one end in the axial direction. The retaining portions 49, 50, and 51 cover the outer peripheral areas of the retaining portions 49, 50, and 51 with the plate-shaped cover member 64, thereby preventing the gears 40, 41, and 42 from falling off. I have.

A magnetic flux collection holder 52 is arranged below the substrate 45. The magnetic flux collecting holder 52 is formed of a nonmagnetic material, for example, a resin material and has a substantially closed cylindrical shape, and has a through hole through which the input shaft 20 passes at a substantially central position. Magnetic flux collection rings 53 and 54 are provided in the outer peripheral area of the through hole. A magnetic shielding member housing 70 is provided at a position corresponding to the first and second gear magnetic sensors 46 and 47 on a partial area of the magnetic flux collecting holder 52. A magnetic shielding plate (magnetic shielding member) 55 made of a thin magnetic shielding material is mounted.
Further, a first yoke 56 and a second yoke 57 formed of a magnetic material on the output shaft 21 are provided below the magnetic flux collection holder 52.

  As shown in an enlarged manner in FIG. 3, female screw holes 58, 59, 60 into which a plurality of screws (not shown) inserted from the side of the steering angle sensor holder member 48 are screwed are provided on the outer peripheral side of the magnetic flux collecting holder 52. Are formed penetrating along the axial direction. Engagement protrusions 61 and 62 are formed adjacent to the female screw holes 59 and 60, respectively. The cover member 64, the steering angle sensor holder member 48, the substrate 45, and the magnetic flux collecting holder 52 are fastened and fixed together by the screws screwed into the female screw holes 58, 59, 60 and the engagement projections 61, 62.

The magnetic shielding member housing 70 is formed of, for example, a resin material, and has a magnetic shielding member housing main body 70a, an elastic connecting portion 70b, and engagement holes 70c and 70d.
On the other hand, the magnetic shielding plate 55 is formed of a magnetic material, for example, SPCC (cold rolled steel plate), and as shown in FIG. It has notches 55c for nap fitting corresponding to the parts 55a and 55b and the elastic connection part 70b. The magnetic shielding plate 55 has a shape that overlaps the entire first gear magnet 43 and the entire second gear magnet 44 on a plane perpendicular to the rotation axis of the steering shaft 15 (input shaft 20). .

The magnetic shielding plate 55 has protrusions 55a and 55b inserted into the engagement holes 70c and 70d of the magnetic shielding member housing 70, and the notch 55c is engaged with the elastic connecting portion 70b of the magnetic shielding member housing 70, and the magnetic shielding plate 55 is magnetic. It is held in a state sandwiched between the shielding member housing main body 70a and the elastic connecting portion 70b.
Further, the magnetic shielding plate 55 has an overlap area overlapping the first yoke 56 or the second yoke 57 on a plane perpendicular to the rotation axis of the steering shaft 15, and the steering shaft 15 (input shaft 20). The outer edge of the magnetic shielding plate 55 on a plane perpendicular to the rotation axis is formed so as not to have a protrusion and a notch in the overlap region.

  FIG. 5 shows a part of the torque sensor 24 shown in FIG. 1 with a cutout, and shows the configuration of a Hall IC detection type torque sensor as an example. The torque sensor 24 includes an annular torque sensor magnet 65, a pair of first and second yokes 56 and 57 that are arranged radially outside the magnet 65 and are combined with each other in the radial direction. , 57, a pair of first magnetic flux collecting ring 53 and second magnetic flux collecting ring 54 disposed radially opposite to each other, and a Hall IC (magnetic sensor for torque sensor) 63 electrically connected to the substrate 45. Having.

The torque sensor magnet 65 is formed in a substantially cylindrical shape from a magnetic material, and is arranged on the inner peripheral side of each of the claws 56b, 57b of the first yoke 56 and the second yoke 57 so as to face these claws in the radial direction. Is done.
The first yoke 56 is provided on the output shaft (second shaft member) 21 and is made of a magnetic material. The first yoke 56 has a first annular portion 56a and a plurality of first claw portions 56b, and a plurality of first claw portions 56b. Is provided on the first annular portion 56a, and the plurality of first claw portions 56b are arranged side by side in the circumferential direction of the rotation axis of the output shaft 21, and are provided to face the torque sensor magnet 65. I have.

The second yoke 57 is provided on the output shaft (second shaft member) 21, is made of a magnetic material, has a second annular portion 57a and a plurality of second claw portions 57b, and a plurality of second claw portions 57b. Is provided on the second annular portion 57a, and each of the plurality of second claw portions 57b is alternately arranged with each of the plurality of first claw portions in the circumferential direction of the rotation axis of the output shaft 21. And, it is provided to face the torque sensor magnet 65.
The first claw portion 56b and the second claw portion 57b are radially outside the torque sensor magnet 65 and on the same circumference, respectively, and the first claw portion 56b and the second claw portion 57b are arranged in the circumferential direction. Are arranged alternately at substantially equal intervals.

FIG. 6A is a cross-sectional view of a plane orthogonal to the axis of the torsion bar 22 in the portion of the Hall IC 63 in FIG. FIG. 6B schematically shows the arrangement of the first and second yokes 56 and 57, the first and second magnetic flux collection rings 53 and 54, and the Hall IC 63 described above. First and second magnetism collecting rings 53 and 54 are arranged between a first yoke 56 and a second yoke 57 arranged concentrically so as to surround the torsion bar 22. Is provided with a Hall IC 63.
The torque sensor 24 collects the magnetic flux generated between the first and second yokes 56 and 57 by the first and second magnetic flux collecting rings 53 and 54, and the magnetic flux between the first and second magnetic flux collecting rings 53 and 54. It is detected by the arranged Hall IC 63.

  In the above-described configuration, from the neutral position (zero torque) of the steering shaft 15 (rack bar 18) as shown in FIG. 7A, the torque (torsion bar torsion) as shown by an arrow TA in FIG. ) Occurs, the first yoke 56 is magnetized to the N pole, and the second yoke 57 is magnetized to the S pole. Thereby, the magnetic flux is generated from the first magnetic flux collecting ring 53 toward the second magnetic flux collecting ring 54 via the Hall IC 63 as shown by the arrow MA in FIG.

  FIGS. 8A and 8B show the arrangement of the steering angle sensor magnets (first and second gear magnets 43 and 44) in the present invention. FIG. 8A shows the arrangement of the first and second gear magnets 43 and 44 on the magnetic shielding plate 55 when the rack bar 18 is at the neutral position, and FIG. Shows the polarities of the first and second gear magnets 43 and 44 when are in the neutral position. The first and second gear magnets 43 and 44 are provided in a region between the first gear magnet 43 and the second gear magnet 44 on a plane perpendicular to the rotation axis of the steering shaft 15 (torsion bar 22). The first magnetic flux generated by the 1N pole 43n and the first S pole 43s, and the second magnetic flux generated by the second N pole 44n and the second S pole 44s are arranged in the same direction.

  FIG. 9 shows the positional relationship between the magnetic shielding plate 55 and the yokes 56 and 57. In the magnetic shielding plate 55, a straight portion 55d between the protrusion 55a and the protrusion 55b is disposed so as to correspond to the straight portions 53a and 54a of the first and second magnetic flux collection rings 53 and 54. The linear portion 55d of the magnetic shielding plate 55 and the linear portions 53a, 54a of the first and second magnetic flux collecting rings 53, 54 are arranged substantially parallel to a straight line connecting the centers of the first and second gear magnets 43, 44. . The linear portions 53a and 54a of the magnetic flux collection ring are formed at positions separated from the Hall IC 63 so that the Hall IC 63 has less influence on magnetic detection.

  FIG. 10 shows the positional relationship between the magnetic shielding plate 55 and the steering angle sensor magnets (first and second gear magnets 43 and 44). The magnetic shielding plate 55 has a shape that overlaps the entire first gear magnet 43 and the entire second gear magnet 44 on a plane perpendicular to the rotation axis of the steering shaft 15. The magnetic shielding plate 55 has an overlap area overlapping with the first yoke 56 or the second yoke 57 on a plane perpendicular to the rotation axis of the steering shaft 15. The outer edge of the magnetic shielding plate 55 on a plane perpendicular to the plane is formed so as not to have a protrusion and a notch in the overlap region.

  FIG. 11 shows the magnetization direction of the steering angle sensor magnet. The first gear magnet 43 and the second gear magnet 44 are magnetized by so-called axial magnetization. Axial magnetization is to form a pair of north and south poles on both axial sides of the magnet material by applying a strong magnetic field to the axial end surface of the magnet material, which is a magnetic material. The coil for applying a magnetic field applies a magnetic field so as to form both a north pole and a south pole with respect to the axial end face of the material of the magnet. N and S poles are formed. The magnet thus magnetized generates a magnetic field not only in the radial direction of the magnet but also in the axial direction.

  Thus, the first gear magnet 43 has a third north pole provided on the opposite side of the first north pole and a third south pole provided on the opposite side of the first south pole in the direction of the rotation axis of the steering shaft 15. doing. Similarly, the second gear magnet 44 has a fourth north pole provided on the opposite side of the second north pole and a fourth south pole provided on the opposite side of the second south pole in the direction of the rotation axis of the steering shaft 15. doing.

FIG. 12 shows the relationship between the angle of the magnet and the torque fluctuation amount when the first and second gear magnets 43 and 44 are magnetized in the opposite direction (conventional) when the rack bar 18 is at the neutral position [0 °]. Shows the relationship. FIG. 13 also shows the angle and torque of the magnet when the first and second gear magnets 43 and 44 are magnetized in the same direction (in the present invention) when the rack bar 18 is at the neutral position [0 °]. The relationship with the variation is shown. As shown in FIG. 12, when the first and second gear magnets 43 and 44 are magnetized in opposite directions, the torque variation ΔT1 near the neutral position of the rack bar 18 becomes relatively large. On the other hand, as shown in FIG. 13, when the first and second gear magnets 43 and 44 are magnetized in the same direction, the torque variation ΔT2 near the neutral position of the rack bar 18 decreases.
Therefore, when the steering wheel 14 is in the neutral state, the driver does not easily feel the torque fluctuation.

FIG. 14A shows a magnetic simulation result of a magnetic flux density distribution in a case where the magnetization directions of the first and second gear magnets 43 and 44 are different directions when the rack bar 18 is in a neutral state. b) shows a case where the directions of magnetization are the same. As shown in FIG. 14A, if the directions of magnetization are different, a local saturation region SA is generated between the first and second gear magnets 43 and 44, and the magnetic shield plate 55 of the magnetic field associated with the saturation is generated. Leakage of magnetic flux may occur.
On the other hand, if the directions of magnetization are the same, no saturation region is generated between the first and second gear magnets 43 and 44 as shown in FIG. Can be suppressed.

  FIGS. 15A and 15B respectively show the distribution of the magnetic flux density when the magnetization directions of the first and second gear magnets 43 and 44 in FIGS. 14A and 14B are respectively rotated by 90 °. 9 shows the results of a magnetic simulation. In both FIGS. 15A and 15B, the saturation regions SA1 and SA2 are generated between the first and second gear magnets 43 and 44. However, the saturation regions SA1 in FIG. In comparison, in FIG. 15B in which the S and S poles face each other, the saturation region SA2 is smaller, and the influence on the detection accuracy of the torque sensor 24 due to the magnetic field of the first and second gear magnets 43 and 44 is reduced. Can be suppressed.

Here, technical ideas that can be grasped from the above-described embodiment will be described below together with their effects.
The steering device 11 is, in one aspect thereof,
A steering mechanism 12, including a steering shaft 15 and a turning shaft 18,
The steering shaft 15 is rotatable with a driver's steering operation, and includes a first shaft member 20, a second shaft member 21, and a torsion bar 22,
The first shaft member 20 and the second shaft member 21 are connected via the torsion bar 22,
The steered shaft 18 can steer steered wheels 16, 17 with the rotation of the steering shaft 15.
The steering mechanism 12,
A torque sensor magnet 65, which is provided on the first shaft member 20, has an annular shape, and N poles and S poles are alternately arranged in a circumferential direction with respect to a rotation axis of the steering shaft 15;
The torque sensor magnet 65;
A first yoke 56, which is provided on the second shaft member 21 and is made of a magnetic material, and has a first annular portion 56a and a plurality of first claw portions 56b;
The plurality of first claw portions 56b are provided on the first annular portion 56a, and each of the plurality of first claw portions 56b is arranged side by side in the circumferential direction of the rotation axis of the second shaft member 21. And is provided so as to face the torque sensor magnet 65.
The first yoke 56;
A second yoke 57 provided on the second shaft member 21 and made of a magnetic material, having a second annular portion 57a and a plurality of second claw portions 57b;
The plurality of second claw portions 57b are provided on the second annular portion 57a, and each of the plurality of second claw portions 57b is connected to the plurality of The first claw portions 56b are arranged alternately with each other, and are provided to face the torque sensor magnet 65.
The second yoke 57,
A magnetic sensor 63 for a torque sensor, which is provided between the first annular portion 56a and the second annular portion 57a and outputs a signal in accordance with a magnetic field of a field where the magnetic sensor 63 for a torque sensor is provided. Output,
A magnetic sensor 63 for the torque sensor;
A first gear 41, which is rotatable with the rotation of the steering shaft 15, a rotation axis of the first gear 41 is parallel to a rotation axis of the steering shaft 15, and a first gear body; A plurality of first teeth,
The plurality of first teeth are provided on an outer peripheral side of the first gear body.
The first gear 41,
The second gear 42 is rotatable with the rotation of the steering shaft. The rotation axis of the first gear 41 is parallel to the rotation axis of the steering shaft 15. With a second tooth of
The plurality of second teeth are provided on the outer peripheral side of the second gear body, and provided in a number that is indivisible from the number of the first teeth.
The second gear 42;
A first gear magnet 43, which is provided on the first gear main body and has a first north pole and a first south pole, which are a pair of magnetic poles;
The first gear magnet 43;
A second gear magnet 44, provided on the second gear main body, having a pair of magnetic poles, a second north pole and a second south pole,
When the steered shaft 18 is in the neutral position, the first N magnet is located in a region between the first gear magnet 43 and the second gear magnet 44 on a plane perpendicular to the rotation axis of the steering shaft 15. A first magnetic flux generated by the pole and the first south pole, and a second magnetic flux generated by the second north pole and the second south pole are arranged in the same direction;
The second gear magnet 44;
A first gear magnetic sensor for detecting a rotation angle of the first gear based on a change in a magnetic field of the first gear magnet;
The first gear magnetic sensor 46;
A second gear magnetic sensor 47 for detecting a rotation angle of the second gear 42 based on a change in a magnetic field of the second gear magnet 44;
The second gear magnetic sensor 47;
A magnetic shielding member 55 made of a magnetic material, which overlaps with the first gear magnetic sensor 46 and the second gear magnetic sensor 47 on a plane perpendicular to the rotation axis of the steering shaft 15; Wrapping,
The magnetic shielding member 55;
The electric actuator 31, based on an output signal of the torque sensor magnetic sensor 63, an output signal of the first gear magnetic sensor 46, and an output signal of the second gear magnetic sensor 47, Giving steering force,
The electric actuator 31,
It is characterized by having.

  According to the above configuration, when the first gear magnet 43 and the second gear magnet 44, which are the steering angle sensor magnets, are close to the first yoke 56 or the second yoke 57 of the torque sensor 24, these first and second yokes are used. The magnetic fields 56 and 57 receive the magnetic fields of the first and second gear magnets 43 and 44 and may affect the detection accuracy of the torque sensor 24. This effect is easily felt by the driver when the vehicle is traveling straight, in other words, when the steering wheel 14 is in the neutral state. This is because the assist torque is often close to zero when the vehicle is traveling straight, and the ratio of the detection torque of the torque sensor 24 due to the decrease in the detection accuracy of the first and second gear magnets 43 and 44 becomes relatively large. That's why.

  In the present invention, in a straight traveling state of the vehicle, on a plane perpendicular to the rotation axis of the steering shaft 15, the first magnetic flux generated by the first north pole and the first south pole and the second magnetic pole generated by the second north pole and the second south pole. The second magnetic flux is arranged so as to face the same direction. In other words, the first N pole and the second N pole are arranged so as to face in the same direction. In this state, the magnetic field in the magnetic shielding member 55, particularly in the region between the first gear magnetic sensor 46 and the second gear magnetic sensor 47, smoothly circulates, The occurrence of excessive saturation is suppressed. Therefore, the leakage of the magnetic field due to the saturation from the magnetic shielding member 55 is suppressed, and the influence on the detection accuracy of the torque sensor 24 due to the magnetic field of the first and second gear magnets 43 and 44 can be suppressed.

In a preferred embodiment of the steering device 11, the magnetic shielding member 55 has an overlap area that overlaps with the first yoke 56 or the second yoke 57 on a plane perpendicular to the rotation axis of the steering shaft 15. And
The outer edge of the magnetic shielding member 55 on a plane perpendicular to the rotation axis of the steering shaft 15 does not have a protrusion and a notch in the overlap region.

  According to the above configuration, the magnetic shield member 55 and the first and second yokes 56 and 57 are brought close to each other to such an extent that they overlap, thereby suppressing an increase in the radial dimension of the entire apparatus. In this overlap region, the first and second yokes 56 and 57 are easily affected by the magnetic field from the magnetic shielding member 55. In particular, if the magnetic shielding member 55 has protrusions or notches, magnetic saturation is likely to occur in these portions, and the magnetic field may have a greater effect on the first and second yokes 56 and 57.

  Therefore, in the overlap region, the occurrence of magnetic saturation is suppressed by providing, for example, a linear shape, an arc shape, or a smooth curved shape without providing a projection or a notch, and thereby suppressing the occurrence of the first and second gears. The influence of the magnets 43 and 44 on the detection accuracy of the torque sensor 24 can be suppressed.

In yet another preferred aspect, the apparatus includes a magnetic shielding member housing,
The magnetic shielding member housing is formed of a resin material, and includes a magnetic shielding member housing main body portion and an elastic connection portion,
The magnetic shielding member includes a magnetic shielding member body and a magnetic shielding member protrusion,
The magnetic shielding member protrusion is provided in a region outside the overlap region, and has a shape protruding from the magnetic shielding member main body in a plane perpendicular to the rotation axis of the steering shaft 15. The magnetic shielding member is held in a state sandwiched between the housing main body and the elastic connection portion.

  According to the above configuration, the magnetic shielding member projection is held in a state sandwiched between the magnetic shielding member housing main body and the elastic connection portion, so that the magnetic shielding member can be firmly fixed to the magnetic shielding member housing. . This fixing utilizes the elastic deformation of the elastic connecting portion as in a so-called snap fit. Since the magnetic shielding member can be fixed without using a screw or an adhesive, the assemblability of the device is improved. Can be improved. Since the magnetic shielding member protrusion for fixing is provided at a portion deviating from the overlap region, even if magnetic saturation occurs in the magnetic shielding member projection, the magnetic saturation The influence on the first and second yokes can be suppressed.

  In still another preferred embodiment, the magnetic shielding member 55 overlaps the entire first gear magnet and the entire second gear magnet on a plane perpendicular to the rotation axis of the steering shaft 15. It is characterized by the following.

  According to the above configuration, it is possible to suppress the magnetic field from directly flying from the first and second gear magnets 43 and 44 to the first and second yokes 56 and 57.

In still another preferred embodiment, the first gear magnet 43 includes a third N pole provided on a side opposite to the first N pole in a direction of a rotation axis of the steering shaft 15, and a side opposite to the first S pole. A third south pole provided,
The second gear magnet 44 includes a fourth north pole provided on the opposite side of the second north pole and a fourth south pole provided on the opposite side of the second south pole in the direction of the rotation axis of the steering shaft 15. It is characterized by having.

  According to the above configuration, the first gear magnet 43 and the second gear magnet 44 are magnetized by so-called axial magnetization. Axial magnetization is to form a pair of north and south poles on both axial sides of the magnet material by applying a strong magnetic field to the axial end surface of the magnet material, which is a magnetic material. The coil for applying a magnetic field applies a magnetic field so as to form both a north pole and a south pole with respect to the axial end face of the material of the magnet. N and S poles are formed. The magnet thus magnetized generates a magnetic field not only in the radial direction of the magnet but also in the axial direction.

  On the other hand, the first gear magnet 43 and the second gear magnet 44 are arranged such that the first north pole and the second north pole are in the same direction when the steering shaft 18 is in the neutral position. When the first and second gear magnets 43 and 44 rotate with the rotation, for example, the first S pole of the first gear magnet 43 and the second S pole of the second gear magnet 44 face each other. At this time, the first S pole and the second S pole generate magnetic fields that repel each other in the magnetic shielding member 55. This repelling magnetic field causes a magnetic saturation in the magnetic shielding member 55.

  However, since the first and second gear magnets 43 and 44 are magnetized in the axial direction, the magnetic field generated by the first and second gear magnets 43 and 44 is generated by the first and second gear magnets 43 and 44. Not only the magnetic fields repelling each other, but also the magnetic fields flying in the axial direction in each of the first and second gear magnets 43 and 44, the magnetic fields repelling each other are relatively small. Therefore, the occurrence of magnetic saturation in the magnetic shielding member 55 can be suppressed as compared with the case where the first and second gear magnets 43 and 44 are not magnetized in the axial direction.

  The configurations described in the above embodiments are only schematically shown to the extent that the present invention can be understood and implemented. Therefore, the present invention is not limited to the embodiments described above, and can be modified in various forms without departing from the scope of the technical idea described in the claims.

  DESCRIPTION OF SYMBOLS 11 ... Steering device, 12 ... Steering mechanism, 13 ... Steering assist mechanism, 14 ... Steering wheel, 15 ... Steering shaft (steering shaft), 16, 17 ... Tire (steering wheel), 18 ... Rack bar (steering shaft), 18a: rack teeth, 19: rack and pinion mechanism, 20: input shaft (first shaft member), 21: output shaft (second shaft member), 21a: pinion teeth, 22: torsion bar, 23: steering angle sensor, Reference numeral 24: Torque sensor, 25, 26: Tie rod, 31: Electric motor (electric actuator), 32: Control device (ECU), 33: Transmission mechanism, 34: CAN bus, 35: Sensor harness, 41: First gear, 42 ... second gear, 43 ... first gear magnet, 44 ... second gear magnet, 45 ... substrate, 46 ... magnetic sensor for first gear , 47: magnetic sensor for second gear, 52: magnetic flux collecting holder, 53: first magnetic flux collecting ring, 54: second magnetic flux collecting ring, 55: magnetic shielding plate (magnetic shielding member), 56: first yoke, 56a ... First annular portion, 56b First claw portion, 57 Second yoke, 57a Second annular portion, 57b Second claw portion, 63 Hall IC (magnetic sensor for torque sensor), 64 Cover Member, 65: Torque sensor magnet

Claims (5)

In the steering device,
A steering mechanism, including a steering axis and a turning axis,
The steering shaft is rotatable with a driver's steering operation, and includes a first shaft member, a second shaft member, and a torsion bar,
The first shaft member and the second shaft member are connected via the torsion bar,
The steered shaft, with the rotation of the steering shaft, can steer steered wheels,
The steering mechanism;
A torque sensor magnet, provided on the first shaft member, having an annular shape, and N poles and S poles are alternately arranged in a circumferential direction with respect to a rotation axis of the steering shaft;
The torque sensor magnet;
A first yoke, provided on the second shaft member, formed of a magnetic material, having a first annular portion and a plurality of first claws;
The plurality of first claw portions are provided on the first annular portion, and each of the plurality of first claw portions is arranged side by side in a circumferential direction of a rotation axis of the second shaft member, and Provided opposed to the torque sensor magnet,
The first yoke;
A second yoke, provided on the second shaft member, formed of a magnetic material, having a second annular portion and a plurality of second claws;
A plurality of the second claw portions are provided on the second annular portion, and each of the plurality of the second claw portions is a plurality of the first claw portions in a circumferential direction of a rotation axis of the second shaft member. Are arranged alternately with each other, and are provided facing the torque sensor magnet,
The second yoke;
A magnetic sensor for a torque sensor, which is provided between the first annular portion and the second annular portion, and outputs a signal in accordance with a magnetic field of a field provided with the magnetic sensor for a torque sensor.
A magnetic sensor for the torque sensor;
A first gear, which is rotatable with rotation of the steering shaft, a rotation axis of the first gear is parallel to a rotation axis of the steering shaft, a first gear body, and a plurality of first gears. Equipped with teeth
The plurality of first teeth are provided on an outer peripheral side of the first gear body.
Said first gear;
A second gear that is rotatable with the rotation of the steering shaft, a rotation axis of the first gear is parallel to a rotation axis of the steering shaft, a second gear body, and a plurality of second gears. Equipped with teeth
The plurality of second teeth are provided on the outer peripheral side of the second gear body, and provided in a number that is indivisible from the number of the first teeth.
Said second gear;
A first gear magnet, which is provided on the first gear main body and has a first north pole and a first south pole, which are a pair of magnetic poles;
Said first gear magnet;
A second gear magnet, provided on the second gear body, having a pair of magnetic poles, a second north pole and a second south pole;
When the steered shaft is in the neutral position, the first N-pole and the second N-pole are located in a region between the first gear magnet and the second gear magnet on a plane perpendicular to the rotation axis of the steering shaft. A first magnetic flux generated by a 1S pole and a second magnetic flux generated by the second N pole and the second S pole are arranged so as to face in the same direction;
Said second gear magnet;
A magnetic sensor for a first gear, which detects a rotation angle of the first gear based on a change in a magnetic field of the first gear magnet,
A magnetic sensor for the first gear;
A magnetic sensor for a second gear, which detects a rotation angle of the second gear based on a change in a magnetic field of the second gear magnet;
A magnetic sensor for the second gear;
A magnetic shielding member, which is formed of a magnetic material and overlaps with the first gear magnetic sensor and the second gear magnetic sensor on a plane perpendicular to the rotation axis of the steering shaft. ,
The magnetic shielding member,
An electric actuator that applies a steering force to the steering mechanism based on an output signal of the torque sensor magnetic sensor, an output signal of the first gear magnetic sensor, and an output signal of the second gear magnetic sensor. ,
Said electric actuator,
A steering device comprising: The steering device according to claim 1, wherein the magnetic shielding member has an overlap area overlapping the first yoke or the second yoke on a plane perpendicular to a rotation axis of the steering shaft,
An outer edge of the magnetic shielding member on a plane perpendicular to a rotation axis of the steering shaft has no protrusion and notch in the overlap region. The steering device according to claim 2 includes a magnetic shielding member housing,
The magnetic shielding member housing is formed of a resin material, and includes a magnetic shielding member housing main body portion and an elastic connection portion,
The magnetic shielding member includes a magnetic shielding member body and a magnetic shielding member protrusion,
The magnetic shielding member projection is provided in a region deviating from the overlap region, and has a shape protruding from the magnetic shielding member main body in a plane perpendicular to the rotation axis of the steering shaft, A steering device, wherein the steering device is held between the magnetic shielding member housing main body and the elastic connection portion.   2. The steering device according to claim 1, wherein the magnetic shielding member overlaps the entire first gear magnet and the entire second gear magnet on a plane perpendicular to the rotation axis of the steering shaft. A steering device. 2. The steering device according to claim 1, wherein the first gear magnet includes a third N pole provided on a side opposite to the first N pole and a side opposite to the first S pole in a direction of a rotation axis of the steering shaft. 3. Has a third south pole provided at
The second gear magnet has a fourth north pole provided on the opposite side of the second north pole and a fourth south pole provided on the opposite side of the second south pole in the direction of the rotation axis of the steering shaft. A steering device.