Torque sensor

Abstract

In order to suppress the influence of an external magnetic field when detecting torque while minimizing increases in manufacturing costs, a torque sensor 10 comprises: a housing 20 inside which a stator 50 and a magnet 55 are disposed; and a collector assembly 40 having a magnetic collecting yoke 43 and a Hall effect IC 45 to detect changes in magnetic flux, wherein the housing 20 has an accommodation part 25 for accommodating the collector assembly 40, the magnetic collecting yoke 43 has a first magnetic collecting yoke 43a and a second magnetic collecting yoke 43b flanking the Hall effect IC 45 from both sides in the axial direction of a first pinion gear 88a, and a magnetic shield cover 70 with a first shield part 71 covering the accommodation part 25 from one side in the axial direction and a second shield part 72 covering the accommodation part 25 from the other side in the axial direction is attached to the accommodation part 25.

Description

Torque Sensor

[0001] The present disclosure relates to a torque sensor.

[0002] One example of a torque sensor that detects torque applied to a rotating body of a steering device is one that detects torque by detecting changes in magnetism. For example, a sensor device described in Patent Document 1 includes a permanent magnet fixed to an input shaft, two magnetic yokes fixed to an output shaft, two magnetic flux collector rings that induce magnetic flux from the magnetic yokes, and a magnetic sensor that detects the magnetic flux induced in the magnetic flux collector rings.

[0003] The sensor device described in Patent Document 1 also includes a magnetic shield that radially covers the magnetic collecting ring, and an external magnetic shield that is attached to the outer surface of the housing that houses the permanent magnet and magnetic yoke and has a portion that overlaps with the magnetic sensor. This allows the magnetic shield and the external magnetic shield to block magnetic noise transmitted to the magnetic sensor, thereby improving the detection accuracy of the sensor.

[0004] Japanese Patent Application Laid-Open No. 2021-135139

[0005] However, when a magnetic shield is provided to block magnetic noise transmitted to the magnetic flux collecting ring and suppress the influence of external magnetic fields, the magnetic shield must be provided over a wide area around the magnetic flux collecting ring, which tends to result in a complex shape. This makes it difficult to manufacture the magnetic shield and also to install the magnetic shield, which tends to increase manufacturing costs. Therefore, it has been difficult to suppress the influence of external magnetic fields when detecting torque while suppressing increases in manufacturing costs.

[0006] The present disclosure has been made in consideration of the above, and aims to provide a torque sensor that can suppress the influence of an external magnetic field when detecting torque while suppressing an increase in manufacturing costs.

[0007] The torque sensor of the present disclosure comprises a collector assembly having a stator fixed to a shaft, a cylindrical magnet arranged opposite the stator, a housing inside which the shaft, the stator, and the magnet are arranged, a magnetism collecting yoke that detects changes in magnetic flux in response to changes in the relative positions of the stator and the magnet, and a Hall element that converts the changes in magnetic flux detected by the magnetism collecting yoke into an electrical signal and outputs the electrical signal, wherein the housing has an accommodating portion that protrudes radially outward from the shaft and accommodates the collector assembly, the magnetism collecting yoke has a first magnetism collecting yoke and a second magnetism collecting yoke that sandwich the Hall element from both sides in the axial direction of the shaft when the collector assembly is accommodated in the accommodating portion, and a magnetic shield cover is attached to the accommodating portion, the first shielding portion covering the accommodating portion from one side in the axial direction and a second shielding portion covering the accommodating portion from the other side in the axial direction.

[0008] According to this configuration, even if a magnetic body approaches the housing portion inside which the magnetic flux collecting yoke and the Hall element are disposed, the magnetic shield cover can shield the external magnetic field acting on the Hall element from the axial direction, which is the direction of magnetic flux detection by the Hall element. This suppresses the influence of external magnetic fields when detecting changes in magnetic flux acting on the stator from the magnet using the magnetic flux collecting yoke and the Hall element, allowing the torque sensor to properly detect steering torque. Furthermore, because the magnetic flux collecting yoke and the Hall element are housed in the housing portion, the magnetic shield cover does not need to have a complex shape. By covering the housing portion from both sides in the axial direction, the magnetic flux from the magnetic body outside the torque sensor can be shielded from the magnetic flux collecting yoke and the Hall element. This allows the magnetic shield cover to shield the external magnetic field without requiring a complex shape, thereby reducing the cost of manufacturing the magnetic shield cover. As a result, the influence of external magnetic fields on torque detection can be suppressed while suppressing increases in manufacturing costs.

[0009] In a preferred embodiment, at least one of the first shield portion and the second shield portion is disposed so as to overlap the Hall element in the axial direction.

[0010] With this configuration, the magnetic shield cover can shield the Hall element from an external magnetic field acting on the Hall element in the axial direction, which is the direction of magnetic flux detection by the Hall element, by using the first shield part and the second shield part that are arranged to overlap the Hall element. This allows the magnetic shield cover to suppress the influence of the external magnetic field when the Hall element detects changes in magnetic flux acting on the stator from the magnet. As a result, the influence of the external magnetic field when detecting torque can be suppressed.

[0011] In a preferred embodiment, the magnetic shield cover is attached to the housing together with the collector assembly by a fastening member that attaches the collector assembly to the housing.

[0012] With this configuration, the magnetic shield cover is attached to the housing together with the collector assembly by fastening members, eliminating the need for additional members to attach the magnetic shield cover to the housing, thereby reducing the number of parts. Also, because the magnetic shield cover is attached to the housing together with the collector assembly by fastening members, the number of work steps required to attach the collector assembly and magnetic shield cover to the housing can be reduced. As a result, increases in manufacturing costs can be suppressed.

[0013] In a preferred embodiment, the magnetic shield cover has a shield mounting portion that is attached to the accommodating portion from the outside in the radial direction, and the collector assembly has a flange portion that is attached to the accommodating portion from the outside in the radial direction, and the magnetic shield cover is attached to the accommodating portion by the fastening member with the flange portion of the collector assembly interposed between the shield mounting portion and the accommodating portion.

[0014] With this configuration, the magnetic shield cover is attached to the housing with fastening members, with the flange of the collector assembly interposed between the shield mounting portion and the housing, so the magnetic shield cover and the collector assembly can be attached to the housing with a common fastening member. This reduces the number of parts and the number of work steps required to attach the collector assembly and magnetic shield cover to the housing. As a result, increases in manufacturing costs can be suppressed.

[0015] In a preferred embodiment, the collector assembly has a connector portion to which an external connector is connected, the shield mounting portion has a through hole through which the connector portion passes, and the connector portion passes through the through hole from the inside to the outside in the radial direction.

[0016] With this configuration, the connector portion of the collector assembly penetrates the through-hole of the shield mounting portion from the inside to the outside in the radial direction, so that the shield mounting portion can shield from external magnetic fields while enabling connection between an external connector and the connector portion. This ensures electrical connection between the Hall element of the collector assembly and an external control device, thereby ensuring a torque detection path, while also shielding from external magnetic fields with the magnetic shield cover. As a result, steering torque can be detected appropriately while suppressing the influence of external magnetic fields on torque detection.

[0017] In a preferred embodiment, the housing has a first housing and a second housing connected to each other, the first housing has the accommodating portion, the first shielding portion covers the accommodating portion from the side opposite to where the second housing is located in the axial direction, and the second shielding portion covers the accommodating portion from the side where the second housing is located in the axial direction.

[0018] With this configuration, when the housing has a first housing having a storage portion and a second housing connected to the first housing, the first and second shield portions of the magnetic shield cover cover the storage portion from opposite sides in the axial direction, making it easy to obtain a structure that shields the magnetic collection yoke and the Hall element from external magnetic fields from external magnetic bodies. This makes it possible to suppress the influence of external magnetic fields when detecting torque while suppressing increases in manufacturing costs.

[0019] In a preferred embodiment, the accommodating portion is positioned near the portion of the first housing that is connected to the second housing, the radial diameter of the end of the second housing that is connected to the first housing is larger than the radial diameter of the portion of the first housing opposite the side where the second housing is located relative to the accommodating portion, and the radial length of the second shielding portion of the magnetic shield cover is shorter than the radial length of the first shielding portion.

[0020] According to this configuration, the radial length of the surface of the accommodating portion on the side where the second housing is located is shorter than the radial length of the surface opposite the side where the second housing is located. Meanwhile, the radial length of the second shield portion of the magnetic shield cover covering the surface of the accommodating portion on the side where the second housing is located is shorter than the radial length of the first shield portion covering the surface opposite the side where the second housing is located. Therefore, the magnetic shield cover can cover the accommodating portion from both sides in the axial direction over as wide an area as possible, even if the accommodating portion has different radial protrusion amounts from the housing on both sides in the axial direction. This allows the magnetic shield cover to shield the magnetic field acting on the inside of the accommodating portion from a magnetic body that can approach the accommodating portion formed by protruding from the housing. As a result, the influence of external magnetic fields on torque detection can be suppressed.

[0021] In a preferred embodiment, the accommodating portion has an opening that opens outward in the radial direction, and the collector assembly is accommodated in the accommodating portion by being inserted into the inside of the accommodating portion through the opening.

[0022] With this configuration, the collector assembly is inserted into the housing through its opening, allowing the collector assembly to be easily positioned inside the housing. This allows the magnetism collecting yoke and Hall element of the collector assembly to be easily positioned inside the housing, making it easy to position the magnetism collecting yoke in an appropriate position relative to the stator. As a result, it is possible to appropriately detect steering torque while suppressing increases in manufacturing costs.

[0023] In a preferred embodiment, the collector assembly includes a sensor housing to which the circuit board on which the Hall element is arranged and the magnetic flux collecting yoke are attached, and an O-ring is disposed between the outer peripheral surface of the sensor housing and the inner peripheral surface of the accommodating portion so as to abut against both.

[0024] With this configuration, an O-ring is disposed in contact with both the outer circumferential surface of the sensor housing and the inner circumferential surface of the accommodation portion, thereby preventing water and other substances from entering the accommodation portion, thereby preventing damage to the Hall element caused by water and other substances entering the accommodation portion and ensuring durability.

[0025] In a preferred embodiment, the collector assembly has a lid portion that covers the circuit board attached to the sensor housing, and the O-ring is disposed radially outward from a position where the lid portion is disposed.

[0026] With this configuration, the circuit board can be sealed without disposing a seal member between the sensor housing and the lid, which reduces the number of seal members required to prevent water and other substances from entering the circuit board. This reduces the number of parts and the number of steps required to assemble the collector assembly to the housing. As a result, durability can be maintained while suppressing increases in manufacturing costs.

[0027] The torque sensor according to the present disclosure has the advantage of being able to suppress the influence of an external magnetic field when detecting torque while suppressing an increase in manufacturing costs.

[0028] FIG. 1 is a schematic diagram for explaining a steering device according to an embodiment. FIG. 2 is a cross-sectional view including a torque sensor in the steering device according to the embodiment. FIG. 3 is a cross-sectional view at a different position in the circumferential direction from FIG. 2. FIG. 4 is a schematic diagram for explaining an overview of a magnet, a stator, and a magnetic collecting yoke of the torque sensor. FIG. 5 is a detailed view of the periphery of the torque sensor shown in FIG. 2. FIG. 6 is an exploded perspective view of a collector assembly. FIG. 7 is an exploded side view of the collector assembly and a magnetic shield cover. FIG. 8 is a detailed view of a portion where the collector assembly and the magnetic shield cover are attached to a first housing. FIG. 9 is a detailed view showing a state before the magnetic shield cover is attached to the first housing shown in FIG. 8. FIG. 10 is a detailed view showing a state before the collector assembly is attached to the first housing shown in FIG. 9.

[0029] The present disclosure will be described in detail below with reference to the drawings. Note that the present disclosure is not limited to the following modes for carrying out the invention (hereinafter referred to as embodiments). Furthermore, the components in the following embodiments include those that can be easily imagined by a person skilled in the art, those that are substantially the same, and those that are within the so-called equivalent range. Furthermore, the components disclosed in the following embodiments can be combined as appropriate.

[0030] [Embodiment] Fig. 1 is a schematic diagram for explaining a steering device 80 according to an embodiment. As shown in Fig. 1, the steering device 80 includes, in the order in which a force applied by an operator is transmitted, a steering wheel 81, a steering shaft 82, a universal joint 84, an intermediate shaft 85, a universal joint 86, a stub shaft 87, a steering gear 88, and a tie rod 89. The steering device 80 also includes a control device (hereinafter referred to as an ECU (Electronic Control Unit)) 100, a torque sensor 10, and an electric motor 102. A vehicle speed sensor 101 is provided in the vehicle and outputs a vehicle speed signal V to the ECU 100 via CAN (Controller Area Network) communication.

[0031] The steering shaft 82 is connected to the steering wheel 81 at one end and to a universal joint 84 at the other end.

[0032] Intermediate shaft 85 is connected at one end to universal joint 84 and at the other end to universal joint 86. Stub shaft 87 is connected at one end to universal joint 86 and at the other end to torque sensor 10. Torque sensor 10 is connected at one end to stub shaft 87 and at the other end to a first pinion gear 88a of steering gear 88.

[0033] More specifically, the first pinion gear 88a is a shaft-shaped member having a gear (not shown) that meshes with a rack bar 88b (described later) formed on the end opposite to the side connected to the stub shaft 87, and the stub shaft 87 and the first pinion gear 88a are connected via a torsion bar 87a (see FIG. 2). One end of the torsion bar 87a is connected to the stub shaft 87, and the other end is connected to the first pinion gear 88a, and the torsion bar 87a transmits rotational torque between the stub shaft 87 and the first pinion gear 88a.

[0034] Torque sensor 10 is a torque detection device that detects torque acting on a shaft connected to torque sensor 10, and detects rotational torque transmitted between stub shaft 87 and first pinion gear 88a via torsion bar 87a. In other words, stub shaft 87 and first pinion gear 88a, which are connected via torsion bar 87a, are shafts that are the detection target when torque is detected by torque sensor 10.

[0035] The steering gear 88 includes a first pinion gear 88a, a rack bar 88b, and a second pinion gear 88c. The first pinion gear 88a is connected to the stub shaft 87 via a torsion bar 87a. Rack teeth (not shown) formed on the rack bar 88b mesh with the gear of the first pinion gear 88a. The rack bar 88b also meshes with the second pinion gear 88c at a position different from that of the first pinion gear 88a.

[0036] An electric motor 102 is connected to the second pinion gear 88c via a worm reduction gear (not shown), and the second pinion gear 88c is rotatable by driving force transmitted from the electric motor 102. The electric motor 102 rotates the second pinion gear 88c via a worm reduction gear (not shown). The electric motor 102 is, for example, a brushless motor, but may also be a motor including brushes (sliders) and a commutator (commutator).

[0037] The steering gear 88 converts the rotational motion transmitted to the first pinion gear 88a and the second pinion gear 88c into linear motion by a rack bar 88b disposed inside a rack housing 90. The steering device 80 according to this embodiment is of a dual pinion assist type in which the rack bar 88b performs linear motion using the rotational motion transmitted from the first pinion gear 88a and the second pinion gear 88c. The tie rod 89 is connected to the rack bar 88b. In other words, the steering device 80 is a rack-and-pinion type electric power steering device.

[0038] The torque sensor 10 detects, as steering torque, the steering force of the driver transmitted to the steering shaft 82 via the steering wheel 81. The vehicle speed sensor 101 detects the traveling speed (vehicle speed) of the vehicle on which the steering device 80 is mounted. The electric motor 102, the torque sensor 10, and the vehicle speed sensor 101 are electrically connected to the ECU 100.

[0039] The ECU 100 controls the operation of the electric motor 102. The ECU 100 also acquires signals from the torque sensor 10 and the vehicle speed sensor 101. That is, the ECU 100 acquires the steering torque T from the torque sensor 10 and the vehicle speed signal V from the vehicle speed sensor 101. When the ignition switch 103 is on, the ECU 100 is supplied with power from a power supply device (e.g., an on-board battery) 104. The ECU 100 calculates an assist steering command value of the assist command based on the steering torque T and the vehicle speed signal V. The ECU 100 then adjusts the power value X to be supplied to the electric motor 102 based on the calculated assist steering command value. The ECU 100 acquires, as operation information Y, information on an induced voltage from the electric motor 102 or information output from a rotation detection device such as a resolver provided in the electric motor 102.

[0040] The steering force of the operator (driver) input to the steering wheel 81 is transmitted to the first pinion gear 88a. The steering force transmitted to the first pinion gear 88a is then transmitted to the tie rod 89 via the steering gear 88, displacing the wheels.

[0041] Furthermore, the steering force input by the operator to the steering wheel 81 is transmitted to the torque sensor 10, which is arranged in the steering force transmission path from the steering wheel 81 to the first pinion gear 88a. At this time, the ECU 100 acquires the steering torque T from the torque sensor 10 and acquires the vehicle speed signal V from the vehicle speed sensor 101. Then, the ECU 100 controls the operation of the electric motor 102. The auxiliary steering torque generated by the electric motor 102 is transmitted to the second pinion gear 88c.

[0042] The auxiliary steering torque transmitted to the second pinion gear 88c is transmitted to the tie rod 89 via the steering gear 88, displacing the wheels. That is, the steering device 80 displaces the wheels using not only the steering force of the operator transmitted to the rack bar 88b via the first pinion gear 88a, but also the auxiliary steering torque of the electric motor 102 transmitted to the rack bar 88b via the second pinion gear 88c.

[0043] 1, the steering device 80 is of a dual pinion type in which an assist force is applied to the second pinion gear 88c, but is not limited to this. The steering device 80 may be, for example, a column assist type electric power steering device in which an assist force is applied to the steering shaft 82, or a single pinion assist type electric power steering device in which an assist force is applied to the first pinion gear 88a. Furthermore, the steering device 80 may be a rack assist type electric power steering device in which an assist force is applied to the rack bar 88b without going through a pinion, such as a ball screw type electric power steering device in which an assist force is applied to the rack bar 88b by a ball screw.

[0044] Fig. 2 is a cross-sectional view of a cross section including the torque sensor 10 in a steering device according to an embodiment. Fig. 3 is a cross-sectional view at a different position in the circumferential direction from Fig. 2. In the following description, unless a specific direction is specified, the axial direction of the stub shaft 87 or the first pinion gear 88a on which the torque sensor 10 is disposed will also be described as the axial direction of the torque sensor 10. Similarly, the circumferential direction centered on the axis of the stub shaft 87 or the first pinion gear 88a will also be described as the circumferential direction of the torque sensor 10, and the radial direction centered on the axis of the stub shaft 87 or the first pinion gear 88a will also be described as the radial direction of the torque sensor 10.

[0045] A housing 20 is disposed around the portion of the stub shaft 87 and the first pinion gear 88a that is connected via the torsion bar 87a. The housing 20 includes a first housing 21 and a second housing 31 that are connected to each other. The first housing 21 is disposed axially closer to the stub shaft 87 and mainly covers the stub shaft 87, while the second housing 31 is axially closer to the first pinion gear 88a and mainly covers the first pinion gear 88a. In other words, at least a portion of the stub shaft 87 and the first pinion gear 88a are disposed inside the first housing 21 and the second housing 31, and at least a portion of the stub shaft 87 is disposed inside the first housing 21, and at least a portion of the first pinion gear 88a is disposed inside the second housing 31. The first housing 21 is attached to the second housing 31 by mounting bolts 37 , whereby the first housing 21 is fixed to the second housing 31 .

[0046] A bearing (not shown) is disposed inside the first housing 21, and the stub shaft 87 is rotatably supported by the first housing 21 via the bearing disposed inside the first housing 21. A bearing (not shown) is also disposed inside the second housing 31, and the first pinion gear 88a is rotatably supported by the second housing 31 via the bearing disposed inside the second housing 31.

[0047] The stub shaft 87 is rotatably supported by the first housing 21, and the first pinion gear 88a is rotatably supported by the second housing 31, so that the stub shaft 87 and the first pinion gear 88a, which are connected via the torsion bar 87a, are rotatably supported as a single unit by the first housing 21 and the second housing 31.

[0048] The housing 20 is mounted non-rotatably to the vehicle body, and the housing 20 rotatably supports the stub shaft 87 and the first pinion gear 88a by means of bearings arranged in the first housing 21 and bearings arranged in the second housing 31.

[0049] The torque sensor 10 is disposed within the first housing 21 and is located near the ends of a stub shaft 87, which is a first shaft, and a first pinion gear 88a, which is a second shaft connected to the stub shaft 87 via a torsion bar 87a. The stub shaft 87 and the first pinion gear 88a are both shafts having hollow portions, and the end of one shaft extends into the inside of the other shaft from the end of the other shaft. In this embodiment, the stub shaft 87 extends into the inside of the first pinion gear 88a.

[0050] The torsion bar 87a is disposed from the inside of the stub shaft 87 to the inside of the first pinion gear 88a, with one end connected to the stub shaft 87 and the other end connected to the first pinion gear 88a. In other words, the stub shaft 87 and the first pinion gear 88a are not directly connected, but are connected via the torsion bar 87a, which is a shaft-shaped member. As a result, the stub shaft 87 and the first pinion gear 88a are capable of relative rotation, and when torsion occurs in the torsion bar 87a, the stub shaft 87 and the first pinion gear 88a rotate relative to each other in response to the torsion bar 87a twisting.

[0051] The torque sensor 10 is positioned near the end of the stub shaft 87 and the first pinion gear 88a, which are connected via the torsion bar 87a as described above, and by detecting the angle of relative rotation between the stub shaft 87 and the first pinion gear 88a, it is possible to detect the torque acting between the stub shaft 87 and the first pinion gear 88a.

[0052] The torque sensor 10 has a magnet 55, a stator 50 (see FIG. 4), and a magnetic flux collecting yoke 43 (see FIG. 4). The magnet 55 and the stator 50 are separately attached to a stub shaft 87 and a first pinion gear 88a, respectively. The magnetic flux collecting yoke 43 is attached to a sensor housing 41 of the collector assembly 40, and thus the magnetic flux collecting yoke 43 is included in the collector assembly 40. The magnetic flux collecting yoke 43 is fixed to the first housing 21 by attaching the collector assembly 40 to the first housing 21.

[0053] The collector assembly 40 is accommodated in a accommodating portion 25 of the first housing 21. The accommodating portion 25 is disposed near a portion of the first housing 21 that is connected to the second housing 31, and is formed to protrude radially outward from the outer peripheral surface of the first housing 21. The accommodating portion 25 of the first housing 21 has a space formed inside the accommodating portion 25 that communicates with the inside of the first housing 21, and the collector assembly 40 is accommodated in the accommodating portion 25 by being disposed inside the accommodating portion 25 thus formed.

[0054] Furthermore, a magnetic shield cover 70 is attached to the accommodating portion 25 of the first housing 21. The magnetic shield cover 70 is formed by bending a metal plate member. Both axial sides of the accommodating portion 25 are covered by the magnetic shield cover 70 attached to the accommodating portion 25. More specifically, the magnetic shield cover 70 is formed to extend radially inward from a position closer to the radial outer side of the accommodating portion 25 on both axial sides of the accommodating portion 25. As a result, both axial sides of the accommodating portion 25 are covered by the magnetic shield cover 70 extending in the radial direction.

[0055] The torque sensor 10 configured as described above is capable of detecting torque based on the change in magnetism that occurs when the torsion bar 87a twists and the stub shaft 87 and the first pinion gear 88a rotate relative to each other.

[0056] 4 is a schematic diagram illustrating an overview of the magnet 55, stator 50, and magnetic flux collecting yoke 43 of the torque sensor 10. One of the magnet 55 and stator 50 of the torque sensor 10 is attached to a first shaft, and the other is attached to a second shaft. In this embodiment, the magnet 55 is attached to a stub shaft 87, which is the first shaft, and the stator 50 is attached to a first pinion gear 88a, which is the second shaft. Of these, the magnet 55 is formed in a substantially cylindrical shape and is a multi-pole magnet in which a plurality of north poles and south poles are arranged alternately in the circumferential direction.

[0057] The stator 50 has a flange portion 51 and teeth portions 52. The flange portion 51 is formed in an annular plate shape with its thickness direction being the axial direction. The teeth portions 52 extend from the inner periphery of the annular flange portion 51 toward the axial direction of the flange portion 51 and are formed in a plate shape with their thickness direction being oriented in the radial direction of the flange portion 51. Furthermore, multiple teeth portions 52 are arranged side by side at intervals in the circumferential direction of the flange portion 51.

[0058] The stator 50 thus formed includes a pair of stators 50, a first stator 50a and a second stator 50b, each having an identical shape. The first stator 50a and the second stator 50b each have a flange portion 51 and teeth portions 52. That is, the first stator 50a has an annular first flange portion 51a and a plurality of first teeth portions 52a, and the second stator 50b has an annular second flange portion 51b and a plurality of second teeth portions 52b. The first stator 50a and the second stator 50b are both attached to the same shaft with their flange portions 51 positioned coaxially and oriented in a direction away from the other stator 50. In this embodiment, the first stator 50a and the second stator 50b are both attached to the first pinion gear 88a.

[0059] That is, the first stator 50a is disposed with the first teeth 52a extending from the first flange 51a toward the second stator 50b, and the second stator 50b is disposed with the second teeth 52b extending from the second flange 51b toward the first stator 50a. In this case, since multiple first teeth 52a and multiple second teeth 52b are provided at intervals on the first flange 51a and the second flange 51b, the first stator 50a and the second stator 50b are combined such that the teeth 52 of one stator 50 are located in portions of the circumferential direction where the teeth 52 of the other stator 50 are not located.

[0060] The magnet 55 attached to the stub shaft 87 is disposed inside the first stator 50a and second stator 50b combined in this manner. The magnet 55 and the stator 50 are disposed such that their axial directions coincide with the axial directions of the stub shaft 87 and the first pinion gear 88a. Therefore, the magnet 55 and the stator 50 are attached to the stub shaft 87 and the first pinion gear 88a in a positional relationship in which the outer peripheral surface of the magnet 55 faces the teeth 52 of the stator 50. Because the magnet 55 and the stator 50 are disposed in this positional relationship, when torque is transmitted between the stub shaft 87 and the first pinion gear 88a via the torsion bar 87a and the stub shaft 87 and the first pinion gear 88a rotate slightly relative to each other, the relative positional relationship between the magnet 55 and the stator 50 changes, and the magnetic flux acting from the magnet 55 on the stator 50 changes accordingly.

[0061] Further, a magnetism collecting yoke 43 of the collector assembly 40 is disposed near the stator 50. The magnetism collecting yoke 43 is a member for detecting changes in the magnetic flux acting on the stator 50 from the magnet 55, and is disposed near a flange portion 51 of the stator 50. Since the stator 50 is provided with a pair of a first stator 50a and a second stator 50b, the magnetism collecting yoke 43 is also provided with a pair of a first magnetism collecting yoke 43a and a second magnetism collecting yoke 43b corresponding to the pair. That is, the first magnetism collecting yoke 43a of the magnetism collecting yoke 43 is disposed near the first flange portion 51a of the first stator 50a, and the second magnetism collecting yoke 43b is disposed near the second flange portion 51b of the second stator 50b.

[0062] The pair of magnetic flux collecting yokes 43 are located between two flange portions 51 of the stator 50 and overlap the flange portions 51 of the stator 50 with a gap in the axial direction. That is, the first magnetic flux collecting yoke 43a is located near the surface of the first flange portion 51a of the first magnetic flux collecting yoke 43a where the second flange portion 51b is located, and the second magnetic flux collecting yoke 43b is located near the surface of the second flange portion 51b of the second magnetic flux collecting yoke 43b where the first flange portion 51a is located. These magnetic flux collecting yokes 43 overlap the flange portions 51 of the stator 50 within a predetermined range in the circumferential direction. That is, the portions of the first and second magnetic collecting yokes 43a and 43b that overlap with the flange portion 51 of the stator 50 are formed in an approximately fan shape (see Figure 6), and as a result, the first and second magnetic collecting yokes 43a and 43b are arranged to overlap with a portion of the flange portion 51 of the stator 50 in the circumferential direction.

[0063] In this way, by positioning the magnetic flux collecting yoke 43 near the flange portion 51, the magnetic flux collecting yoke 43 is able to detect changes in magnetic flux corresponding to changes in the relative positions of the stator 50 and the magnet 55. In other words, the magnetic flux collecting yoke 43 is able to detect changes in the magnetic flux acting on the stator 50 from the magnet 55 when the stub shaft 87 and the first pinion gear 88a rotate slightly relative to each other.

[0064] Furthermore, a Hall IC 45 is disposed between the two magnetic flux collecting yokes 43. The Hall IC 45 is disposed between the magnetic flux collecting yokes 43, away from the portion of the magnetic flux collecting yoke 43 located near the flange portion 51 of the stator 50. That is, the Hall IC 45 is sandwiched between the first magnetic flux collecting yoke 43a and the second magnetic flux collecting yoke 43b of the magnetic flux collecting yoke 43. The Hall IC 45 includes a Hall element (not shown) that detects changes in magnetic flux detected by the magnetic flux collecting yoke 43, and an output circuit (not shown) that converts the output voltage output from the Hall element in response to the changes in magnetic flux into a digital electrical signal. This allows the Hall IC 45 to detect changes in magnetic flux density acting on the two magnetic flux collecting yokes 43, convert the detected changes in magnetic flux density into an electrical signal, and output the signal as an electrical signal. Note that a magnetic sensor utilizing the magnetoresistance effect or the tunneling magnetoresistance effect can be used instead of the Hall IC. In short, it is sufficient if the change in magnetic flux density occurring between the magnetic flux collecting yokes 43 can be output as an electrical signal.

[0065] 5 is a detailed view of the torque sensor 10 and its surroundings shown in FIG. 2. The magnet 55 is attached to the stub shaft 87 by a first sleeve 56. The first sleeve 56 is a cylindrical member, and the first sleeve 56 is attached to the stub shaft 87 by press-fitting the stub shaft 87 into the first sleeve 56. The magnet 55 is fixed to the outer peripheral surface of the first sleeve 56 by, for example, an adhesive, so that the magnet 55 can rotate integrally with the stub shaft 87.

[0066] The stator 50 is attached to the first pinion gear 88a by the second sleeve 53 and the carrier 54. The second sleeve 53 is a cylindrical member, and the first pinion gear 88a is press-fitted into the second sleeve 53, thereby attaching the second sleeve 53 to the first pinion gear 88a. The carrier 54 is a cylindrical member, and is formed integrally with the second sleeve 53 by injection molding. Therefore, when the second sleeve 53 is attached to the first pinion gear 88a, the carrier 54 is also attached to the first pinion gear 88a together with the second sleeve 53.

[0067] The carrier 54, which is attached to the first pinion gear 88a by the second sleeve 53, is supported by the second sleeve 53 and is positioned from the first pinion gear 88a toward the stub shaft 87, and is positioned radially outward from the stub shaft 87. Furthermore, the carrier 54 is positioned in the same axial position as the magnet 55, and is positioned radially outward from the magnet 55.

[0068] The stators 50 are attached to the carrier 54 arranged in this manner. More specifically, the first stator 50a and the second stator 50b are attached to the carrier 54 with the teeth 52 located radially inside the carrier 54 and the flanges 51 protruding from the radially inside to the radially outside of the carrier 54. As a result, the pair of stators 50, the first stator 50a and the second stator 50b, are both arranged in the same position as the magnet 55 in the axial direction, and are arranged radially outside the magnet 55.

[0069] Furthermore, the first stator 50a and the second stator 50b are attached to a carrier 54 that is formed integrally with the second sleeve 53 that is attached to the first pinion gear 88a, and are therefore rotatable integrally with the first pinion gear 88a. The stator 50 thus arranged to be rotatable integrally with the first pinion gear 88a includes a flange portion 51 that protrudes radially outward from the first pinion gear 88a, and is fixed to the first pinion gear 88a.

[0070] As described above, the magnet 55 is fixed to the stub shaft 87 and the stator 50 is fixed to the first pinion gear 88a, so that the magnet 55 and the stator 50 are arranged inside the housing 20 together with the stub shaft 87 and the first pinion gear 88a.

[0071] A spigot recess 32 is formed on the inner surface of the second housing 31 at a position near the end of the side that is connected to the first housing 21 in the axial direction. The spigot recess 32 is a recess into which the spigot protrusion 22 of the first housing 21 fits.

[0072] The spigot recess 32 is formed on the end side of the second housing 31 where the first housing 21 is disposed. The first housing 21, which is fixed to the second housing 31, is formed with a spigot protrusion 22 that fits into the spigot recess 32. The spigot protrusion 22 is formed to protrude in the axial direction from the first housing 21 toward the side where the second housing 31 is located, and the first housing 21 is positioned radially relative to the second housing 31 by the spigot protrusion 22 fitting into the spigot recess 32.

[0073] The spigot protrusion 22 is formed in a cylindrical shape and protrudes from the first housing 21, with an outer diameter slightly smaller than the inner diameter of the spigot recess 32. A groove into which an O-ring 23, which is a sealing member, is fitted is formed on the outer peripheral surface of the spigot protrusion 22, and the spigot protrusion 22 enters the spigot recess 32 with the O-ring 23 fitted in the groove. As a result, when the spigot protrusion 22 enters the spigot recess 32, the O-ring 23 ensures sealing between the first housing 21 and the second housing 31.

[0074] The first housing 21 and the second housing 31 are connected by attaching the first housing 21 to the second housing 31 with the mounting bolt 37, with the inlay convex portion 22 of the first housing 21 inserted into the inlay concave portion 32 of the second housing 31.

[0075] The collector assembly 40 is accommodated in the accommodation portion 25 formed in the first housing 21, and is attached to the accommodation portion 25 in an orientation in which the Hall IC 45 is sandwiched from both sides in the axial direction by the first magnetic flux collecting yoke 43 a and the second magnetic flux collecting yoke 43 b when accommodated in the accommodation portion 25. More specifically, the Hall IC 45 is disposed on a circuit board 44 included in the collector assembly 40, and the circuit board 44 is attached to a sensor housing 41 included in the collector assembly 40.

[0076] The magnetism collecting yoke 43 is attached to the sensor housing 41 in an orientation in which the Hall IC 45 is sandwiched between the first magnetism collecting yoke 43a and the second magnetism collecting yoke 43b from both sides in the thickness direction of the circuit board 44. In this embodiment, the first magnetism collecting yoke 43a is located on the side where the stub shaft 87 is located in the axial direction, and the second magnetism collecting yoke 43b is located on the side where the first pinion gear 88a is located in the axial direction. The collector assembly 40 is housed in the housing 25 in an orientation in which the thickness direction of the circuit board 44 on which the Hall IC 45 is arranged is the axial direction. As a result, when the collector assembly 40 is housed in the housing 25, the first magnetism collecting yoke 43a and the second magnetism collecting yoke 43b sandwich the Hall IC 45 from both sides in the axial direction.

[0077] Furthermore, the accommodating portion 25 of the first housing 21 is formed to protrude radially outward, with its axial position close to the axial positions of the stub shaft 87 and the magnet 55 and stator 50 fixed to the first pinion gear 88a, which are arranged inside the housing 20. As a result, when the collector assembly 40 is accommodated in the accommodating portion 25, the first magnetic flux collecting yoke 43a and the second magnetic flux collecting yoke 43b of the collector assembly 40 can be disposed between the first flange portion 51a of the first stator 50a and the second flange portion 51b of the second stator 50b, which are fixed to the first pinion gear 88a.

[0078] The collector assembly 40 housed in the housing 25 has a lid 42. The lid 42 is a member that covers a circuit board 44 attached to the sensor housing 41. The collector assembly 40 has a first lid 42a that is disposed on the opposite side of the circuit board 44 in the axial direction from the side where the second housing 31 is located and that covers the circuit board 44, and a second lid 42b that is disposed on the side of the circuit board 44 where the second housing 31 is located and that covers the circuit board 44.

[0079] An O-ring 47, which is a sealing member that contacts both the outer peripheral surface of the sensor housing 41 of the collector assembly 40 housed in the housing portion 25 and the inner peripheral surface of the housing portion 25, is disposed between the two. The O-ring 47 is disposed radially outward from the position where the lid portion 42 is disposed.

[0080] More specifically, a stepped portion 41d is formed on the outer peripheral surface of the sensor housing 41 of the collector assembly 40 in a portion radially outward from the position where the lid portion 42 is disposed. The stepped portion 41d has an outer peripheral surface that is one step lower than the portion radially outward from the stepped portion 41d. That is, the stepped portion 41d is formed as a notch-like shape in which the outer peripheral surface of the sensor housing 41 is cut out all the way around. The O-ring 47 has an inner peripheral surface that is fitted into the stepped portion 41d of the sensor housing 41 and abuts against the sensor housing 41, and an outer peripheral surface that abuts against the inner peripheral surface of the accommodation portion 25, thereby abutting against both the outer peripheral surface of the sensor housing 41 and the inner peripheral surface of the accommodation portion 25.

[0081] The magnetic shield cover 70 attached to the accommodating portion 25 of the first housing 21 has a first shield portion 71 and a second shield portion 72. The first shield portion 71 is a portion that covers the accommodating portion 25 from one axial side. The second shield portion 72 is a portion that covers the accommodating portion 25 from the other axial side. As a result, the accommodating portion 25 that accommodates the collector assembly 40 is covered on both axial sides by the magnetic shield cover 70 attached to the accommodating portion 25. In this embodiment, the first shield portion 71 covers the accommodating portion 25 from the side opposite to the side where the second housing 31 is located in the axial direction, and the second shield portion 72 covers the accommodating portion 25 from the side where the second housing 31 is located in the axial direction.

[0082] At least one of the first shield portion 71 and the second shield portion 72 of the magnetic shield cover 70 is arranged to overlap in the axial direction with the Hall IC 45 of the collector assembly 40 housed in the housing portion 25. In this embodiment, of the first shield portion 71 and the second shield portion 72, the first shield portion 71, which covers the housing portion 25 from the side opposite to the side where the second housing 31 is located, is arranged to overlap in the axial direction with the Hall IC 45 of the collector assembly 40. More specifically, the radial diameter of the end of the second housing 31 connected to the first housing 21 is larger than the radial diameter of a portion of the first housing 21 opposite to the side where the second housing 31 is located in the axial direction with respect to the housing portion 25. Furthermore, the radial diameter of a portion of the first housing 21 on the side where the spigot protrusion 22 is located in the axial direction with respect to the housing portion 25 is larger than the radial diameter of a portion of the first housing 21 opposite to the side where the spigot protrusion 22 is located in the axial direction with respect to the housing portion 25.

[0083] For this reason, the accommodating portion 25, which is disposed near the portion of the first housing 21 that is coupled to the second housing 31, has a smaller radial protrusion from the outer peripheral surface of the first housing 21 at the portion on the side where the second housing 31 is located in the axial direction than at the portion on the opposite side of the side where the second housing 31 is located in the axial direction. In other words, the radial length of the surface of the accommodating portion 25 on the side where the second housing 31 is located in the axial direction is shorter than the radial length of the surface on the opposite side of the side where the second housing 31 is located in the axial direction. As a result, the magnetic shield cover 70 that covers the accommodating portion 25 from both sides of the accommodating portion 25 in the axial direction has a shorter radial length of the second shield portion 72 than the radial length of the first shield portion 71.

[0084] That is, the first shield part 71 is formed from near the radially outer end of the accommodating part 25 to a position near the outer peripheral surface of the first housing 21, and the second shield part 72 is formed from near the radially outer end of the accommodating part 25 to a position near the outer peripheral surface of the second housing 31. For this reason, of the two axial surfaces of the accommodating part 25, the second shield part 72, which covers the surface on which the second housing 31 is located and which is formed to have a relatively short radial length, has a shorter radial length than the first shield part 71, which covers the surface on the opposite side of the side on which the second housing 31 is located.

[0085] Next, the configuration of the collector assembly 40 will be described. Fig. 6 is an exploded perspective view of the collector assembly 40. Fig. 7 is an exploded side view of the collector assembly 40 and the magnetic shield cover 70. Note that Fig. 6 is a perspective view seen from the opposite side in the axial direction to the collector assembly 40 shown in Fig. 5 and Figs. 8 to 10 described below, in order to illustrate the circuit board 44. The collector assembly 40 has a sensor housing 41, a lid portion 42, a magnetic collecting yoke 43, a circuit board 44, and a connection terminal 46.

[0086] The sensor housing 41 has a flange portion 41a, a connector portion 41b, and a circuit board placement portion 41c. The flange portion 41a is a portion that attaches the collector assembly 40 to the accommodating portion 25 from the radial outside. The flange portion 41a is a plate-shaped member formed with its thickness direction oriented in the radial direction. The flange portion 41a is formed with bushing insertion holes 41aa that penetrate the flange portion 41a in the thickness direction and in which bushings 48 are placed. The bushing insertion holes 41aa are formed at two positions corresponding to two screw holes 27 (see FIG. 10 ) that are formed in the accommodating portion 25, which will be described later. The bushings 48 placed in the bushing insertion holes 41aa are members made of a metal material and formed in a substantially cylindrical shape, and are inserted into and held by the bushing insertion holes 41aa.

[0087] The connector portion 41b and the board placement portion 41c are disposed on opposite sides of the plate-shaped flange portion 41a in the thickness direction of the flange portion 41a. The connector portion 41b is a portion to which an external connector (not shown) is connected for outputting an electrical signal from the torque sensor 10 to the outside. The connector portion 41b is disposed between two bushing insertion holes 41aa formed in the flange portion 41a, and is formed to protrude radially outward from the flange portion 41a, i.e., on the side opposite to the side where the board placement portion 41c is located in the thickness direction of the flange portion 41a.

[0088] The board placement portion 41c is formed in a substantially rectangular frame shape when viewed in the axial direction, and the circuit board 44 is placed inside the frame-shaped board placement portion 41c. The magnetic flux collecting yoke 43 has a first magnetic flux collecting yoke 43a and a second magnetic flux collecting yoke 43b, which are arranged on both sides of the circuit board 44 in the axial direction, with respect to the circuit board 44 placed on the board placement portion 41c. The first magnetic flux collecting yoke 43a and the second magnetic flux collecting yoke 43b, which are arranged on both sides of the circuit board 44, are each attached to the board placement portion 41c with the circuit board 44 sandwiched between them.

[0089] The lid portion 42 is a member that covers the frame-shaped board placement portion 41c from both axial sides and covers the circuit board 44 attached to the sensor housing 41, and has a first lid portion 42a and a second lid portion 42b. The first lid portion 42a is attached to the board placement portion 41c, and is disposed on the side of the board placement portion 41c where the first magnetic flux collecting yoke 43a is disposed, while the second lid portion 42b is attached to the board placement portion 41c, and is disposed on the side of the board placement portion 41c where the second magnetic flux collecting yoke 43b is disposed. As a result, the frame-shaped board placement portion 41c, on which the circuit board 44 and magnetic flux collecting yoke 43 are disposed, is covered from both axial sides by the first lid portion 42a and the second lid portion 42b.

[0090] Furthermore, a connection terminal 46 is disposed in the connector portion 41b of the sensor housing 41, and is electrically connected to an external connector. The connection terminal 46 has a plurality of terminal pins 46a and a holding member 46b that holds the plurality of terminal pins 46a together. The connection terminal 46 is disposed inside the connector portion 41b of the sensor housing 41, and one end of the terminal pins 46a is connected to the circuit board 44 disposed in the board mounting portion 41c. The other end of the terminal pin 46a of the connection terminal 46 can be electrically connected to the external connector that is connected to the connector portion 41b.

[0091] In this embodiment, the terminal pin 46a is formed in an L-shape, and the portion connected to the circuit board 44 is connected to the circuit board 44 in the thickness direction of the circuit board 44. The portion of the terminal pin 46a that is electrically connected to an external connector is arranged to extend in the radial direction, thereby enabling the connection terminal 46 to electrically connect the circuit board 44 and the external connector.

[0092] Next, the configuration for attaching the collector assembly 40 and the magnetic shield cover 70 to the first housing 21 will be described. Fig. 8 is a detailed view of the portion where the collector assembly 40 and the magnetic shield cover 70 are attached to the first housing 21. Fig. 9 is a detailed view showing the state before the magnetic shield cover 70 is attached to the first housing 21 shown in Fig. 8. Fig. 10 is a detailed view showing the state before the collector assembly 40 is attached to the first housing 21 shown in Fig. 9. The collector assembly 40 is housed in and attached to the housing portion 25 of the first housing 21. The magnetic shield cover 70 is attached to the housing portion 25 together with the collector assembly 40 by means of mounting bolts 78, which are fastening members that attach the collector assembly 40 to the housing portion 25.

[0093] An opening 26 (see FIG. 10 ) that opens radially outward is formed in the portion of the housing 25 where the collector assembly 40 is attached. The opening 26 of the housing 25 is an opening to the space inside the housing 25. Furthermore, a screw hole 27 is formed on the radially outer surface of the housing 25, on the side of the opening 26, into which a mounting bolt 78 that attaches the collector assembly 40 to the housing 25 is threadedly engaged.

[0094] The collector assembly 40 has a flange portion 41 a attached to the accommodating portion 25 from the outside in the radial direction, and the magnetic shield cover 70 has a shield attachment portion 73 attached to the outside in the radial direction of the accommodating portion 25. The magnetic shield cover 70 is attached to the accommodating portion 25 by threading an attachment bolt 78 into the threaded hole 27 of the accommodating portion 25, with the flange portion 41 a of the collector assembly 40 interposed between the shield attachment portion 73 and the accommodating portion 25.

[0095] More specifically, when attaching the collector assembly 40 to the accommodating portion 25, bushings 48 made of a metal material are inserted into the two bushing insertion holes 41aa (see FIG. 6) of the flange portion 41a, and the bushings 48 are placed in the bushing insertion holes 41aa.

[0096] On the other hand, the magnetic shield cover 70, which is formed by bending a metal plate member, has a shield mounting portion 73 formed with the thickness direction of the plate oriented in the radial direction, and mounting holes 75 are formed in the shield mounting portion 73 at two positions corresponding to the two screw holes 27 formed in the accommodating portion 25. The shield mounting portion 73 also has a through hole 74 through which the connector portion 41 b of the collector assembly 40 passes. The through hole 74 is located between the two mounting holes 75 formed in the shield mounting portion 73 and is formed as a hole that penetrates the shield mounting portion 73 in the thickness direction. The first shield portion 71 and the second shield portion 72 of the magnetic shield cover 70 are formed by bending radially from both sides of the shield mounting portion 73 in the axial direction.

[0097] When attaching the collector assembly 40 and the magnetic shield cover 70 to the accommodating portion 25, the collector assembly 40 is oriented so that the connector portion 41b is positioned radially outward, and the board placement portion 41c is inserted into the inside of the accommodating portion 25 through the opening 26 of the accommodating portion 25. At this time, the collector assembly 40 is inserted with the O-ring 47 fitted into the stepped portion 41d (see FIG. 5) formed on the sensor housing 41. As a result, the board placement portion 41c of the collector assembly 40, on which the magnetic collecting yoke 43 and the circuit board 44 are disposed, is accommodated in the accommodating portion 25, and the O-ring 47 is positioned so as to abut against both the outer peripheral surface of the sensor housing 41 and the inner peripheral surface of the accommodating portion 25.

[0098] The magnetic shield cover 70 is attached by interposing the flange portion 41a of the collector assembly 40, whose board placement portion 41c is housed in the housing portion 25, between the shield mounting portion 73 of the magnetic shield cover 70 and the radially outer surface of the housing portion 25. In this state, the mounting bolt 78 is passed through the mounting hole 75 of the shield mounting portion 73 and the inner hole of the cylinder of the bushing 48 placed in the bushing insertion hole 41aa of the flange portion 41a, and is screwed into the threaded hole 27 formed in the housing portion 25. In this way, the magnetic shield cover 70, together with the collector assembly 40, is attached to the housing portion 25 of the first housing 21 and fixed to the first housing 21.

[0099] At this time, the connector portion 41b of the collector assembly 40 passes through the through-hole 74 of the shield mounting portion 73 from the inside to the outside in the radial direction. As a result, when the magnetic shield cover 70 is attached to the housing portion 25 while covering the housing portion 25, the connector portion 41b of the collector assembly 40 is exposed to the outside of the magnetic shield cover 70, and an external connector can be connected.

[0100] The collector assembly 40, which is fixed to the first housing 21 with the board placement portion 41c accommodated inside the accommodation portion 25, is fixed to the first housing 21 with the magnetic flux collecting yoke 43 of the collector assembly 40 inserted between the flange portions 51 of the pair of stators 50. As a result, the magnetic flux collecting yoke 43 is fixed to the first housing 21 with the first magnetic flux collecting yoke 43a and the second magnetic flux collecting yoke 43b each inserted between the flange portions 51 of the pair of stators 50 and overlapping the flange portions 51 of the stators 50 with a gap in the axial direction.

[0101] When the collector assembly 40 is attached to the first housing 21, the connector portion 41b of the collector assembly 40 is exposed to the outside of the accommodating portion 25 and is also exposed from the magnetic shield cover 70. A connector of a signal line that transmits an electrical signal from the torque sensor 10 to the ECU 100 is connected to the connector portion 41b, and thereby a connection terminal 46 arranged on the connector portion 41b is electrically connected to the signal line that transmits the electrical signal to the ECU 100.

[0102] Next, the operation of the steering device 80 will be described. When the steering wheel 81 is operated while driving a vehicle equipped with the steering device 80, the steering force applied to the steering wheel 81 is transmitted from the steering wheel 81 to the steering shaft 82. The steering force transmitted to the steering shaft 82 is transmitted as steering torque from the steering shaft 82 to the intermediate shaft 85, and from the intermediate shaft 85 via the stub shaft 87 to the first pinion gear 88a. As a result, the steering gear 88 having the first pinion gear 88a converts the rotational motion transmitted from the first pinion gear 88a into linear motion of the rack bar 88b, causing the tie rod 89 to operate.

[0103] The steering device 80 according to this embodiment also includes an electric motor 102 that generates an auxiliary steering torque to assist the driver in steering. The electric motor 102 generates the auxiliary steering torque based on the steering torque detected by the torque sensor 10 disposed between the stub shaft 87 and the first pinion gear 88 a.

[0104] Torque sensor 10 detects the steering torque applied to stub shaft 87 based on the angle of relative rotation between stub shaft 87 and first pinion gear 88a. In other words, because stub shaft 87 and first pinion gear 88a are connected via torsion bar 87a, when steering torque is applied to stub shaft 87, the steering torque is transmitted between stub shaft 87 and first pinion gear 88a via torsion bar 87a. At that time, slight twisting of torsion bar 87a causes relative rotation between stub shaft 87 and first pinion gear 88a.

[0105] In torque sensor 10, magnet 55 is attached to stub shaft 87 and stator 50 is attached to first pinion gear 88a, so that when there is relative rotation between stub shaft 87 and first pinion gear 88a, magnet 55 and stator 50 of torque sensor 10 also rotate relative to each other. The angle of relative rotation between magnet 55 and stator 50 increases as the steering torque acting between stub shaft 87 and first pinion gear 88a increases.

[0106] When the magnet 55 and the stator 50 rotate relative to each other, the magnetic flux acting from the magnet 55 on the stator 50 changes. The magnetic flux collecting yoke 43 arranged near the stator 50 is capable of detecting the change in the magnetic flux acting from the magnet 55 on the stator 50. Therefore, when the magnet 55 and the stator 50 rotate relative to each other in conjunction with the relative rotation of the stub shaft 87 and the first pinion gear 88a, the magnetic flux collecting yoke 43 arranged near the stator 50 can detect the change in the magnetic flux acting from the magnet 55 on the stator 50.

[0107] In this way, the magnetic flux acting on the stator 50 from the magnet 55, which is detected by the magnetism collecting yoke 43, changes depending on the angle of relative rotation between the magnet 55 and the stator 50. The Hall IC 45 detects the magnetic flux, which changes depending on the angle of relative rotation between the magnet 55 and the stator 50 and is detected by the magnetism collecting yoke 43, using a Hall element, converts the detected magnetic flux into an electrical signal using an output circuit, and transmits the signal from the connection terminal 46 to the outside of the first housing 21 and then to the ECU 100. In other words, the torque sensor 10 detects the change in the magnetic flux acting on the stator 50 from the magnet 55 using the magnetism collecting yoke 43 and the Hall IC 45, thereby detecting the steering torque applied to the stub shaft 87 and transmitting the detected steering torque as an electrical signal to the ECU 100.

[0108] The ECU 100 operates the electric motor 102 based on the electrical signal transmitted from the torque sensor 10, causing the electric motor 102 to generate an assist steering torque. In other words, the electrical signal transmitted from the Hall IC 45 of the torque sensor 10 to the ECU 100 changes according to the angle of relative rotation between the magnet 55 and the stator 50, and changes based on the steering torque T acting between the stub shaft 87 and the first pinion gear 88a. Therefore, the ECU 100 uses the electrical signal transmitted from the Hall IC 45 of the torque sensor 10 as information that changes depending on the steering torque T acting on the stub shaft 87 and the first pinion gear 88a, and adjusts the power value X supplied to the electric motor 102 based on the electrical signal transmitted from the Hall IC 45, causing the electric motor 102 to generate an assist steering torque.

[0109] That is, the ECU 100 acquires a signal of steering torque T from the torque sensor 10, acquires a vehicle speed signal V of the vehicle from the vehicle speed sensor 101, and further acquires operation information Y of the electric motor 102 from a rotation detection device provided in the electric motor 102. Based on this operation information Y, the steering torque T, and the vehicle speed signal V, the ECU 100 causes the electric motor 102 to generate an auxiliary steering torque. The auxiliary steering torque generated by the electric motor 102 is transmitted to the second pinion gear 88c. The steering gear 88 having the second pinion gear 88c converts the rotational motion transmitted from the second pinion gear 88c into linear motion of the rack bar 88b. As a result, the steering force applied to the steering wheel 81 by the driver is assisted by the auxiliary steering torque generated by the electric motor 102.

[0110] As described above, the torque sensor 10 detects the steering torque applied to the stub shaft 87 by detecting the change in the magnetic flux acting on the stator 50 from the magnet 55 using the magnetism collecting yoke 43 and the Hall IC 45. Therefore, if magnetic noise acts on the torque sensor 10, the magnetic flux detected by the magnetism collecting yoke 43 and the Hall IC 45 will differ from the magnetic flux detected due to the relative rotation between the magnet 55 and the stator 50, and it may become impossible to detect the steering torque with high accuracy.

[0111] For example, if a magnetic body other than the torque sensor 10 is located near the torque sensor 10, an external magnetic field, which is a magnetic field from the magnetic body, acts on the Hall IC 45, and when the Hall IC 45 detects the magnetic flux of the external magnetic field, the magnetic flux detected by the Hall IC 45 may differ from the magnetic flux acting on the stator 50 from the magnet 55. In other words, the Hall IC 45 may erroneously detect the magnetic flux due to the external magnetic field, and the torque sensor 10 may erroneously detect the steering torque based on the magnetic flux.

[0112] In particular, since the Hall IC 45 is disposed on the circuit board 44 with its thickness oriented in the axial direction and detects magnetic flux from the magnetic flux collecting yoke 43 sandwiched between the Hall IC 45 on both sides in the axial direction, the Hall IC 45 is likely to erroneously detect magnetic flux when an external magnetic field acts on the Hall IC 45 from the axial direction. In other words, if an external magnetic body is located near the housing 25 on the side of the housing 25 where the first housing 21 is located in the axial direction (above the paper surface of the housing 25 in FIG. 5 ) or on the side of the housing 25 where the second housing 31 is located in the axial direction (below the paper surface of the housing 25 in FIG. 5 ), the external magnetic field from the external magnetic body acts on the Hall IC 45 from the axial direction. In this case, the external magnetic field acting on the Hall IC 45 is in the same direction as the direction in which the Hall IC 45 detects magnetic flux from the magnetic flux collecting yoke 43, so the Hall IC 45 is likely to erroneously detect magnetic flux.

[0113] In contrast, in the torque sensor 10 according to this embodiment, a magnetic shield cover 70 is attached to the accommodation portion 25 of the first housing 21 in which the collector assembly 40 is accommodated, to cover the accommodation portion 25. As a result, even if a magnetic body different from the torque sensor 10 approaches the accommodation portion 25 from the axial side where the first housing 21 is located or the axial side where the second housing 31 is located, the magnetic field of the magnetic body can be shielded from the inside of the accommodation portion 25, and the magnetic field of the magnetic body can be prevented from acting on the inside of the accommodation portion 25.

[0114] Therefore, even if a magnetic body other than the torque sensor 10 approaches the housing portion 25, the magnetic field of the magnetic body acts on the magnetism collecting yoke 43 and the Hall IC 45 of the collector assembly 40 housed in the housing portion 25, and it is possible to prevent erroneous detection of magnetic flux by the Hall IC 45. Therefore, the torque sensor 10 can detect the steering torque with high accuracy, and the steering device 80 can generate an auxiliary steering torque based on the steering torque detected by the torque sensor 10.

[0115] As described above, in the torque sensor 10 of the steering device 80 according to this embodiment, the first housing 21 has the accommodating portion 25 that protrudes radially outward, and the magnetic flux collecting yoke 43 is arranged such that the Hall IC 45 is sandwiched from both axial sides between the first magnetic flux collecting yoke 43a and the second magnetic flux collecting yoke 43b when the collector assembly 40 is accommodated in the accommodating portion 25. Also, the accommodating portion 25 is fitted with a magnetic shield cover 70 that has a first shield portion 71 that covers the accommodating portion 25 from the side opposite to the side where the second housing 31 is located in the axial direction, and a second shield portion 72 that covers the accommodating portion 25 from the side where the second housing 31 is located in the axial direction. Therefore, even if a magnetic body approaches the accommodating portion 25, inside which the magnetic flux collecting yoke 43 and the Hall IC 45 are arranged, the magnetic shield cover 70 can shield the external magnetic field from the magnetic body that acts on the Hall IC 45 in the axial direction, which is the direction of magnetic flux detection by the Hall IC 45. This allows the influence of external magnetic fields to be suppressed when detecting changes in the magnetic flux acting on the stator 50 from the magnet 55 using the magnet collecting yoke 43 or the Hall IC 45, and enables the torque sensor 10 to properly detect the steering torque.

[0116] Furthermore, the magnetism collecting yoke 43 and the Hall IC 45 used to detect the magnetic flux acting on the stator 50 from the magnet 55 are housed in the housing portion 25 that protrudes radially outward from the first housing 21. Therefore, the magnetic shield cover 70 does not need to have a complex shape, and by forming a shape that covers the housing portion 25 from both sides in the axial direction, it is possible to shield the magnetism collecting yoke 43 and the Hall IC 45 from the external magnetic field from a magnetic body outside the torque sensor 10. As a result, the magnetic shield cover 70 can shield the external magnetic field without having to have a complex shape, and therefore the cost of manufacturing the magnetic shield cover 70 can be reduced.

[0117] In other words, when a cylindrical magnetic yoke is disposed around a cylindrical permanent magnet and an annular magnetic flux collecting ring is disposed around the magnetic yoke, as in Patent Document 1, to shield the magnetic flux collecting ring from an external magnetic field from an external magnetic body, the magnetic shield must be disposed around the entire circumference of the magnetic flux collecting ring, as in Patent Document 1. In this case, the magnetic shield has a complex shape, which can make manufacturing and installation of the magnetic shield difficult. In contrast, in this embodiment, the magnetic flux collecting yoke 43 and the Hall IC 45 are housed in the housing portion 25 that protrudes radially outward from the first housing 21. Therefore, the magnetic shield cover 70 is shaped to cover the housing portion 25 from both axial sides, thereby shielding the magnetic flux collecting yoke 43 and the Hall IC 45 from an external magnetic field from an external magnetic body. This allows the magnetic shield cover 70 to shield the external magnetic field from the external magnetic body without requiring a complex shape, thereby reducing manufacturing costs. As a result, the influence of external magnetic fields on torque detection can be suppressed while suppressing increases in manufacturing costs.

[0118] Furthermore, at least one of the first shield portion 71 and the second shield portion 72 of the magnetic shield cover 70 is arranged to overlap the Hall IC 45 in the axial direction. Therefore, the magnetic shield cover 70 can shield the Hall IC 45 from an external magnetic field acting on the Hall IC 45 from the axial direction, which is the magnetic flux detection direction of the Hall IC 45, by using the first shield portion 71 and the second shield portion 72 arranged to overlap the Hall IC 45. As a result, the magnetic shield cover 70 can suppress the influence of the external magnetic field when the Hall IC 45 detects changes in the magnetic flux acting on the stator 50 from the magnet 55. As a result, the influence of the external magnetic field when detecting torque can be suppressed.

[0119] Furthermore, the magnetic shield cover 70 is attached to the housing portion 25 together with the collector assembly 40 by the mounting bolts 78 that attach the collector assembly 40 to the housing portion 25. This eliminates the need to provide a separate member for attaching the magnetic shield cover 70 to the housing portion 25, thereby reducing the number of parts. Furthermore, because the magnetic shield cover 70 is attached to the housing portion 25 together with the collector assembly 40 by the mounting bolts 78, the number of work steps required for attaching the collector assembly 40 and the magnetic shield cover 70 to the housing portion 25 can be reduced. As a result, increases in manufacturing costs can be suppressed.

[0120] Furthermore, the magnetic shield cover 70 has a shield mounting portion 73, the collector assembly 40 has a flange portion 41a, and the magnetic shield cover 70 is attached to the housing portion 25 by a mounting bolt 78, with the flange portion 41a of the collector assembly 40 interposed between the shield mounting portion 73 and the housing portion 25. Therefore, the magnetic shield cover 70 and the collector assembly 40 can be appropriately attached to the housing portion 25 by the common mounting bolt 78. This makes it possible to reduce the number of parts and also to reduce the number of work steps required when attaching the collector assembly 40 and the magnetic shield cover 70 to the housing portion 25. As a result, it is possible to suppress increases in manufacturing costs.

[0121] Furthermore, when a cylindrical magnetic yoke is disposed outside a cylindrical permanent magnet and an annular magnetic flux collecting ring is disposed outside the magnetic yoke, as in Patent Document 1, the magnetic shield needs to cover the magnetic flux collecting ring in the axial direction as well. To cover the magnetic flux collecting ring with the magnetic shield in the axial direction, as in Patent Document 1, the magnetic shield needs to be sandwiched and fixed between a housing in which the torque sensor is housed and a housing axially connected to the housing. However, because dimensional errors occur during the manufacturing of components, when the magnetic shield is sandwiched between housings, the error in the relative positional relationship between the component supported by one housing and the component supported by the other housing increases by the dimensional error in the thickness of the magnetic shield plate.

[0122] In this embodiment, the magnetic flux collecting yoke 43 is fixed to the first housing 21, and the stator 50, together with the first pinion gear 88a, is supported by the second housing 31. Therefore, when the magnetic shield cover 70 is sandwiched between the first housing 21 and the second housing 31, an error in the axial distance between the flange portion 51 of the stator 50 and the magnetic flux collecting yoke 43 is likely to increase due to a dimensional error in the plate thickness of the magnetic shield cover 70. In this case, when the magnetic flux collecting yoke 43 detects a change in the magnetic flux acting on the stator 50 from the magnet 55, an error in the detected value is likely to occur due to an error in the distance between the flange portion 51 of the stator 50 and the magnetic flux collecting yoke 43, and therefore an error in the steering torque detected by the torque sensor 10 is likely to occur.

[0123] In contrast, in this embodiment, the magnetic shield cover 70 is not sandwiched between the first housing 21 and the second housing 31, but is attached to the accommodating portion 25 from the radial outside, thereby preventing the magnetic shield cover 70 from increasing the error factor in the relative positional relationship between the stator 50 and the magnetic flux collecting yoke 43. This allows the stator 50 and the magnetic flux collecting yoke 43 to be positioned with high precision, thereby improving the accuracy of magnetic flux detection by the magnetic flux collecting yoke 43. As a result, the magnetic flux acting on the stator 50 from the magnet 55 can be detected with high precision by the magnetic flux collecting yoke 43, allowing steering torque to be detected appropriately.

[0124] Furthermore, the shield mounting portion 73 has a through-hole 74 through which the connector portion 41b of the collector assembly 40 passes, and since the connector portion 41b passes through the through-hole 74 from the inside to the outside in the radial direction, the shield mounting portion 73 can shield from external magnetic fields while enabling connection between an external connector and the connector portion 41b. This ensures electrical connection between the Hall IC 45 of the collector assembly 40 and the ECU 100, thereby ensuring a torque detection path, while also shielding from external magnetic fields with the magnetic shield cover 70. As a result, it is possible to appropriately detect steering torque while suppressing the influence of external magnetic fields when detecting torque.

[0125] The housing 20 includes a first housing 21 having a storage portion 25 and a second housing 31 connected to the first housing 21, and the first shield portion 71 and the second shield portion 72 of the magnetic shield cover 70 cover the storage portion 25 from opposite sides in the axial direction. This makes it easy to obtain a structure that shields the magnetic flux collecting yoke 43 and the Hall IC 45 from external magnetic fields from external magnetic bodies. As a result, it is possible to suppress the influence of external magnetic fields when detecting torque while suppressing increases in manufacturing costs.

[0126] Furthermore, the accommodating portion 25 is disposed near the portion of the first housing 21 that is coupled to the second housing 31, and the radial diameter of the end of the second housing 31 that is coupled to the first housing 21 is larger than the radial diameter of the portion of the first housing 21 that is on the opposite side to the side where the second housing 31 is located with respect to the accommodating portion 25. As a result, the radial length of the surface of the accommodating portion 25 on the side where the second housing 31 is located is shorter than the radial length of the surface opposite to the side where the second housing 31 is located.

[0127] Meanwhile, the magnetic shield cover 70 attached to the accommodation portion 25 thus formed has a radial length of the second shield portion 72 covering the surface on the side where the second housing 31 is located that is shorter than the radial length of the first shield portion 71 covering the surface on the opposite side from the side where the second housing 31 is located. Therefore, the magnetic shield cover 70 can cover the accommodation portion 25, which has different amounts of radial protrusion from the housing 20 on both sides in the axial direction, over as wide an area as possible. This allows the magnetic shield cover 70 to shield the magnetic field acting on the inside of the accommodation portion 25 from a magnetic body that can approach the accommodation portion 25 formed to protrude from the housing 20. As a result, the influence of external magnetic fields on torque detection can be suppressed.

[0128] Furthermore, the accommodation portion 25 is formed with an opening 26 that opens radially outward, and the collector assembly 40 is accommodated in the accommodation portion 25 by being inserted into the inside of the accommodation portion 25 through the opening 26, so that the collector assembly 40 can be easily disposed inside the accommodation portion 25. This makes it possible to easily dispose the magnetic flux collecting yoke 43 and the Hall IC 45 of the collector assembly 40 inside the accommodation portion 25, and to easily dispose the magnetic flux collecting yoke 43 in an appropriate position with respect to the stator 50. As a result, it is possible to appropriately detect steering torque while suppressing increases in manufacturing costs.

[0129] Furthermore, an O-ring 47 is disposed between the outer peripheral surface of the sensor housing 41 of the collector assembly 40 and the inner peripheral surface of the accommodation portion 25, so that it abuts both of them, thereby preventing water and the like from entering the accommodation portion 25. As a result, it is possible to prevent failure of the Hall IC 45 caused by water and the like entering the accommodation portion 25, and durability can be ensured.

[0130] Furthermore, the collector assembly 40 has a lid 42 that covers the circuit board 44, and the O-ring 47 is disposed radially outward of the position where the lid 42 is disposed. This allows sealing of the circuit board 44 without disposing a sealing member between the sensor housing 41 and the lid 42. This reduces the number of sealing members required to prevent water and other contaminants from entering the circuit board 44. This reduces the number of parts and the number of steps required to assemble the collector assembly 40 to the housing 20. As a result, durability is maintained while suppressing increases in manufacturing costs.

[0131] [Modifications] In the above-described embodiment, the first shield portion 71 of the magnetic shield cover 70 is longer in the radial direction than the second shield portion 72, but the first shield portion 71 and the second shield portion 72 may be formed in other shapes. As long as the magnetic shield cover 70 covers as wide an area as possible of the housing portion 25 from both sides of the housing portion 25 in the direction in which magnetic flux is detected by the Hall IC 45 arranged inside the housing portion 25, the relative relationship between the shapes of the first shield portion 71 and the second shield portion 72 does not matter.

[0132] Although the preferred embodiments of the present disclosure have been described above, the present disclosure is not limited to the above-described embodiments. The configurations described as the embodiments and modified examples may be combined as appropriate.

[0133] REFERENCE SIGNS LIST 10 Torque sensor 20 Housing 21 First housing 23, 47 O-ring 25 Storage portion 26 Opening 31 Second housing 37, 78 Mounting bolt 40 Collector assembly 41 Sensor housing 41a Flange portion 41aa Bush insertion hole 41b Connector portion 41c Board placement portion 41d Stepped portion 42 Lid portion 42a First lid portion 42b Second lid portion 43 Magnetic flux collecting yoke 43a First magnetic flux collecting yoke 43b Second magnetic flux collecting yoke 44 Circuit board 45 Hall IC 46 Connection terminal 50 Stator 51 Flange portion 52 Teeth portion 54 Carrier 55 Magnet 70 Magnetic shield cover 71 First shield portion 72 Second shield portion 73 Shield mounting portion 74 Through hole 75 Mounting hole 80 Steering device 81 steering wheel 82 steering shaft 84 universal joint 85 intermediate shaft 86 universal joint 87 stub shaft 87a torsion bar 88 steering gear 88a first pinion gear 88b rack bar 88c second pinion gear 89 tie rod 90 rack housing 100 ECU 101 vehicle speed sensor 102 electric motor 103 ignition switch 104 power supply device

Claims

1. A torque sensor comprising: a stator fixed to a shaft; a cylindrical magnet arranged opposite the stator; a housing inside which the shaft, the stator, and the magnet are arranged; a collector assembly having a magnetism collecting yoke that detects changes in magnetic flux in response to changes in the relative positions of the stator and the magnet, and a Hall element that converts the changes in magnetic flux detected by the magnetism collecting yoke into an electrical signal and outputs it; wherein the housing has a accommodating portion that protrudes outward in the radial direction of the shaft and accommodates the collector assembly, the magnetism collecting yoke has a first magnetism collecting yoke and a second magnetism collecting yoke that sandwich the Hall element from both sides in the axial direction of the shaft when the collector assembly is accommodated in the accommodating portion; and a magnetic shield cover is attached to the accommodating portion, the first shielding portion covering the accommodating portion from one side in the axial direction and a second shielding portion covering the accommodating portion from the other side in the axial direction.

2. The torque sensor according to claim 1, wherein at least one of the first shield portion and the second shield portion is disposed so as to overlap the Hall element in the axial direction.

3. A torque sensor according to claim 1 or 2, wherein the magnetic shield cover is attached to the housing together with the collector assembly by a fastening member that attaches the collector assembly to the housing.

4. A torque sensor as described in claim 3, wherein the magnetic shield cover has a shield mounting portion that is attached to the accommodating portion from the outside in the radial direction, the collector assembly has a flange portion that is attached to the accommodating portion from the outside in the radial direction, and the magnetic shield cover is attached to the accommodating portion by the fastening member with the flange portion of the collector assembly interposed between the shield mounting portion and the accommodating portion.

5. A torque sensor according to claim 4, wherein the collector assembly has a connector portion to which an external connector is connected, the shield mounting portion has a through-hole through which the connector portion passes, and the connector portion passes through the through-hole from the inside to the outside in the radial direction.

6. A torque sensor according to any one of claims 1 to 5, wherein the housing comprises a first housing and a second housing connected to each other, the first housing has the accommodating portion, the first shielding portion covers the accommodating portion from the side opposite to the side where the second housing is located in the axial direction, and the second shielding portion covers the accommodating portion from the side where the second housing is located in the axial direction.

7. A torque sensor as described in claim 6, wherein the accommodating portion is arranged near a portion of the first housing that is connected to the second housing, the radial diameter of the end of the second housing that is connected to the first housing is larger than the radial diameter of a portion of the first housing that is on the opposite side of the side where the second housing is located relative to the accommodating portion, and the magnetic shield cover has a radial length of the second shielding portion that is shorter than the radial length of the first shielding portion.

8. A torque sensor according to any one of claims 1 to 7, wherein the accommodating section has an opening that opens outward in the radial direction, and the collector assembly is accommodated in the accommodating section by being inserted into the inside of the accommodating section through the opening.

9. A torque sensor according to claim 8, wherein the collector assembly comprises a sensor housing to which the magnetic flux collecting yoke and a circuit board on which the Hall element is arranged are attached, and an O-ring is disposed between the outer circumferential surface of the sensor housing and the inner circumferential surface of the accommodating section so as to abut on both.

10. A torque sensor according to claim 9, wherein the collector assembly has a lid that covers the circuit board attached to the sensor housing, and the O-ring is positioned radially outward from a position where the lid is positioned.

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