Torque sensor manufacturing method

Abstract

To provide a method for manufacturing torque sensors that can reduce manufacturing costs. [Solution] A method for manufacturing a torque sensor 10 comprising a magnet 55 attached to the outer circumferential surface of an input shaft 83, in which a plurality of magnetic poles 56 are alternately arranged in the circumferential direction; an output shaft 86 in which convex portions 88b and concave portions 88a are alternately arranged in the circumferential direction on the inner circumferential surface of an insertion hole 87 into which the input shaft 83 is inserted; and a stator 50 attached to the outer circumferential surface of the output shaft 86, having a plurality of teeth portions 52 through which magnetic flux from the magnet 55 flows, wherein a jig magnet 210 for jigging has the same number of magnetic poles as the magnet 55 on its outer circumferential surface, and a jig 200 having a projection 202 that fits into the concave portion 88a formed in the insertion hole 87 of the output shaft 86 is inserted into the insertion hole 87, and the stator 50 is attached to the output shaft 86 by adjusting the position of the teeth portions 52 in the circumferential direction with the magnetic flux from the jig magnet 210 attached to the jig 200 inserted into the insertion hole 87.

Description

Technical Field

[0005] ,

[0001] This disclosure relates to a method for manufacturing a torque sensor.

Background Art

[0002] As an example of a torque sensor that detects the torque applied to a rotating body of a steering device, there is one that detects torque by detecting a change in magnetism. For example, the torque sensor described in Patent Document 1 has a magnet attached to an input shaft and a yoke attached to an output shaft, and detects the relative rotation between the input shaft and the output shaft connected via a torsion bar based on the strength of magnetization of the yoke magnetized by the magnetic force of the magnet, thereby detecting the steering torque.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a torque sensor, since torque is detected based on the relative rotation between a magnet and a yoke, that is, a stator, positioning in the rotational direction of the magnet or stator with respect to the input shaft or output shaft is important. For this reason, in a torque sensor as described in Patent Document 1, embossing is performed on the inner peripheral surface of the stator, and a groove into which the embossing of the stator fits is formed on the outer peripheral surface of the shaft on the side where the stator is attached. When attaching the stator formed in this way to the shaft, the stator is press-fitted onto the shaft while inserting the embossing of the stator into the groove of the shaft, thereby attaching the starter to the shaft while positioning the stator in the rotational direction.

[0005] However, when embossing is applied to the stator for positioning purposes, and grooves corresponding to the embossing are formed on the shaft, these processes must be applied to each individual stator and shaft, which tends to increase manufacturing costs. Therefore, there was room for improvement in terms of manufacturing costs when producing torque sensors.

[0006] This disclosure has been made in view of the above, and aims to provide a method for manufacturing a torque sensor that can reduce manufacturing costs. [Means for solving the problem]

[0007] A method for manufacturing a torque sensor according to the present disclosure includes: a first shaft; an annular permanent magnet attached to the outer circumferential surface of the first shaft, having a plurality of magnetic poles arranged alternately in the circumferential direction; a second shaft having an insertion hole into which the first shaft is inserted, and having a plurality of protrusions projecting inward in the radial direction of the insertion hole and a plurality of recesses recessing outward in the radial direction, arranged alternately in the circumferential direction of the insertion hole on the inner circumferential surface of the insertion hole; and a portion attached to the outer circumferential surface of the second shaft, where the axial position of the second shaft is the same as the permanent magnet attached to the first shaft inserted into the insertion hole, from the permanent magnet A method for manufacturing a torque sensor comprising a stator having a plurality of teeth through which magnetic flux flows, wherein, before inserting the first shaft into the insertion hole of the second shaft, a jig is inserted into the insertion hole, the jig having a cylindrical shape and an annular jig magnet attached to its outer circumference, the same number of magnetic poles as the permanent magnet arranged alternately in the circumferential direction, and a projection that fits into the recess formed in the insertion hole of the second shaft, and the stator is attached to the second shaft by adjusting the position of the teeth in the circumferential direction of the second shaft with the magnetic flux of the jig magnet attached to the jig inserted into the insertion hole.

[0008] With this configuration, before inserting the first shaft into the insertion hole of the second shaft, a jig having a jig magnet and a projection is inserted into the insertion hole of the second shaft to attach the stator to the second shaft. This allows the position of the stator's teeth in the circumferential direction to be adjusted by the magnetic flux of the jig magnet, thereby attaching the stator to the second shaft. As a result, when manufacturing multiple torque sensors, the circumferential positioning of the stator in each torque sensor can be performed using the jig without having to emboss each stator for positioning or form grooves on each second shaft corresponding to the stator's embossing. Therefore, the processing required to position the stator in the circumferential direction during the manufacturing of torque sensors can be reduced, simplifying the manufacturing process. Consequently, manufacturing costs can be reduced.

[0009] In a preferred configuration, the jig has a pressing portion that contacts the stator, and when inserting the jig into the insertion hole of the second shaft, the pressing portion contacts the stator and presses the stator in the axial direction with the pressing portion, thereby press-fitting the stator into the second shaft.

[0010] With this configuration, when inserting the jig into the insertion hole of the second shaft, the stator is pressed into the second shaft by pressing it axially with the push-in part. Therefore, the stator, which has been positioned in the circumferential direction by the jig's magnet, can be pressed into the second shaft by the jig while maintaining the circumferential orientation of the stator. This simplifies the process of positioning the stator in the circumferential direction and attaching the stator to the second shaft. As a result, manufacturing costs can be reduced. [Effects of the Invention]

[0011] The method for manufacturing a torque sensor according to this disclosure has the effect of reducing manufacturing costs. [Brief explanation of the drawing]

[0012] [Figure 1]Figure 1 is a schematic diagram illustrating the steering device according to an embodiment. [Figure 2] Figure 2 is a cross-sectional view of the steering device according to the embodiment, including the torque sensor. [Figure 3] Figure 3 is a schematic diagram illustrating the overview of the magnet, stator, and magnetic collection yoke of a torque sensor. [Figure 4] Figure 4 is an exploded perspective view of the input shaft, output shaft, and torque sensor. [Figure 5] Figure 5 is an explanatory diagram showing how to position the stator in the circumferential direction using a jig. [Figure 6] Figure 6 is a cross-sectional view of the main part showing the jig's insertion part inserted into the insertion hole of the output shaft. [Figure 7] Figure 7 is a detailed view of the area near the tip of the output shaft. [Modes for carrying out the invention]

[0013] The present disclosure will be described in detail below with reference to the drawings. However, the present disclosure is not limited to the embodiments described below. Furthermore, the components in the embodiments below include those easily conceivable by those skilled in the art, those substantially identical, and those within the scope of equivalents. Moreover, the components disclosed in the embodiments below can be combined as appropriate.

[0014] [Embodiment] Figure 1 is a schematic diagram illustrating a steering device 80 according to an embodiment. As shown in Figure 1, the steering device 80 according to the embodiment includes, in the order in which the force applied by the operator is transmitted, a steering wheel 81, a torque sensor 10, an electric motor 101, a reduction gear 102, a universal joint 91, an intermediate shaft 92, and a universal joint 93, all connected to a pinion shaft 94. In the following description, the direction along the central axis AX of the steering shaft 82 will be referred to as the "axial direction," the direction intersecting (orthogonal to) the axial direction will be referred to as the "radial direction," and the direction around the central axis AX will be referred to as the "circumferential direction."

[0015] The steering shaft 82 includes an input shaft 83, an output shaft 86, and a torsion bar 90 (see FIG. 2). The torque sensor 10 detects the torque transmitted between the input shaft 83 and the output shaft 86. The torque sensor 10 will be described in detail later.

[0016] The intermediate shaft 92 connects the universal joint 91 and the universal joint 93. One end of the intermediate shaft 92 is connected to the universal joint 91, and the other end is connected to the universal joint 93. One end of the pinion shaft 94 is connected to the universal joint 93, and the other end is connected to the steering gear 95. The universal joints 91 and 93 are, for example, Cardan joints. The rotation of the steering shaft 82 is transmitted to the pinion shaft 94 via the intermediate shaft 92. Therefore, the intermediate shaft 92 can rotate together with the steering shaft 82.

[0017] The steering gear 95 includes a pinion gear 95a and a rack bar 95b. The pinion gear 95a is connected to the pinion shaft 94. The rack bar 95b meshes with the pinion gear 95a. The steering gear 95 converts the rotational motion transmitted to the pinion gear 95a into a linear motion by the rack bar 95b. The rack bar 95b is connected to the tie rod 96. The angle of the wheel changes as the rack bar 95b moves. That is, the steering device 80 is a rack-and-pinion type electric power steering device.

[0018] The steering device 80 further includes an ECU (Electronic Control Unit) 100 and a vehicle speed sensor 105. The electric motor 101, the vehicle speed sensor 105, and the torque sensor 10 are electrically connected to the ECU 100. The reduction gear 102 is attached to the electric motor 101. The torque sensor 10 outputs the steering torque transmitted to the steering shaft 82 to the ECU 100 via CAN (Controller Area Network) communication. The vehicle speed sensor 105 detects the traveling speed (vehicle speed) of the vehicle body on which the steering device 80 is mounted. The vehicle speed sensor 105 is provided on the vehicle body and outputs the vehicle speed to the ECU 100 via CAN communication.

[0019] The ECU 100 controls the operation of the electric motor 101. The ECU 100 acquires signals from each of the torque sensor 10 and the vehicle speed sensor 105. Power is supplied to the ECU 100 from a power supply device 109 (e.g., an in-vehicle battery) when the ignition switch 108 is in the on state. The ECU 100 calculates an auxiliary steering command value based on the steering torque and the vehicle speed. The ECU 100 adjusts the power value supplied to the electric motor 101 based on the auxiliary steering command value. The ECU 100 acquires information on the induced voltage of the electric motor 101 or information output from a resolver or the like provided on the electric motor 101. By the ECU 100 controlling the electric motor 101, the force required for operating the steering wheel 81 is reduced.

[0020] FIG. 2 is a cross-sectional view of the steering device 80 according to the embodiment, showing a cross-section including the torque sensor 10. As shown in FIG. 2, the steering device 80 includes an input shaft 83 as a first axis, an output shaft 86 as a second axis, a torsion bar 90, a torque sensor 10, a housing 20, and bearings 60, 65. The input shaft 83, the output shaft 86, and the torsion bar 90 have the same central axis AX. The input shaft 83 and the output shaft 86 are connected in the axial direction, and the torsion bar 90 is disposed inside the input shaft 83 and the output shaft 86.

[0021] The input shaft 83 is, for example, a solid shaft. The input shaft 83 is rotatable around the central axis AX. A spline shaft portion (not shown) is formed at the end of the input shaft 83 opposite to the end connected to the output shaft 86, and a steering wheel 81 (see Figure 1) is connected to the spline shaft portion directly or via another shaft. On the radially inner side of the input shaft 83, an insertion hole 83a is formed, extending axially from the end connected to the output shaft 86.

[0022] The output shaft 86 is a cylindrical member having a through hole 86a and a connecting hole 86b extending axially on its radially inward side. The output shaft 86 is positioned relative to the input shaft 83 on the side where the end of the input shaft 83a is located. The output shaft 86 is rotatable around the axis of the central axis AX. The insertion hole 87 has a larger inner diameter than the connecting hole 86b and the through hole 86a, and is formed to a predetermined depth from the end of the output shaft 86 to which the input shaft 83 is connected, towards the opposite side where the input shaft 83 is located. The connecting hole 86b has a larger inner diameter than the through hole 86a, and is formed between the insertion hole 87 and the through hole 86a in the axial direction of the output shaft 86. The through hole 86a extends from the end of the connecting hole 86b opposite to the side where the insertion hole 87 is located, towards the opposite side where the input shaft 83 is located.

[0023] The input shaft 83 has a connecting portion 83b that connects to a connecting hole 86b and an insertion portion 84 that is inserted into an insertion hole 87, near the end of the input shaft 83 on the side where the output shaft 86 is located. The connecting portion 83b is formed at the end of the input shaft 83 on the side where the output shaft 86 is located. The insertion portion 84 is formed adjacent to the connecting portion 83b in the axial direction of the input shaft 83.

[0024] The driving force generated by the electric motor 101 (see Figure 1) is transmitted to the output shaft 86 via the worm 103 and worm wheel 104 of the reduction gear 102. That is, the driving force generated by the electric motor 101 is transmitted to the worm wheel 104 via the worm 103, causing the worm wheel 104 to rotate. The worm 103 is a drive gear that outputs the auxiliary steering torque generated by the electric motor 101. The worm wheel 104 is a driven gear that transmits the auxiliary steering torque to the output shaft 86 by meshing with the worm 103. The worm 103 and worm wheel 104 reduce the rotational speed of the driving force generated by the electric motor 101 and increase the torque.

[0025] The worm wheel 104 has a core metal portion 104a and a wheel tooth portion 104b. The core metal portion 104a is made of, for example, a metal material and is formed in a substantially annular shape. The wheel tooth portion 104b is made of, for example, a resin material and is arranged integrally with the core metal portion 104a on the outer circumference of the core metal portion 104a. The worm wheel 104 is fixed to the output shaft 86 by press-fitting the core metal portion 104a onto the output shaft 86. The worm 103 meshes with the wheel tooth portion 104b of the worm wheel 104. Therefore, the reduction gear 102 transmits the driving force generated by the electric motor 101 to the output shaft 86 with increased torque, and provides auxiliary steering torque to the output shaft 86. That is, the steering device 80 according to this embodiment is a column-assist type electric power steering device in which auxiliary steering torque is applied to the steering shaft 82.

[0026] The torsion bar 90 is a solid elastic member that extends in the axial direction. One end of the torsion bar 90 in the axial direction is inserted into the insertion hole 83a of the input shaft 83. A through hole is formed in the end of the torsion bar 90 that is inserted into the insertion hole 83a of the input shaft 83, extending radially through the bar. A through hole is also formed in the input shaft 83 at the position in the axial direction where the through hole of the torsion bar 90 is formed. The through hole formed in the torsion bar 90 and the through hole formed in the input shaft 83 are in communication with each other. A pin 98 is inserted into the through hole formed in the torsion bar 90 and the through hole formed in the input shaft 83. As a result, the end of the torsion bar 90 that is inserted into the insertion hole 83a of the input shaft 83 is fixed to the input shaft 83 via the pin 98.

[0027] The other axial end of the torsion bar 90 is press-fitted into a through hole 86a formed in the output shaft 86. This fixes the torsion bar 90 to the output shaft 86. In other words, since one end of the torsion bar 90 is fixed to the input shaft 83 and the other end is fixed to the output shaft 86, the input shaft 83 and the output shaft 86 are connected via the torsion bar 90.

[0028] The steering shaft 82 is positioned at least partially inside the housing 20. The housing 20 comprises a first housing 21 and a second housing 25. The first housing 21 is located closer to the input shaft 83 in the axial direction and mainly houses the input shaft 83 of the two output shafts 86. The second housing 25 is located closer to the output shaft 86 in the axial direction and mainly houses the output shaft 86 of the two output shafts 86. The first housing 21 and the second housing 25 are connected in the axial direction. The second housing 25 has space for arranging a worm 103 and a worm wheel 104 inside, and the second housing 25 also serves as a gearbox.

[0029] Bearings 60 and 65 are interposed between the housing 20 and the steering shaft 82, and the steering shaft 82 is rotatably supported relative to the housing 20 by the bearings 60 and 65. Bearing 60 is provided as a first bearing that rotatably supports the output shaft 86 relative to the first housing 21. Bearing 65 is provided as a second bearing that rotatably supports the output shaft 86 relative to the second housing 25.

[0030] Bearings 60 and 65 are positioned on both sides of the output shaft 86 in the axial direction of the position where the worm wheel 104 is fixed. Bearing 60 is positioned on the side of the output shaft 86 where the input shaft 83 is located in the axial direction relative to the position where the core metal portion 104a of the worm wheel 104 is fixed, and bearing 65 is positioned on the opposite side of the input shaft 83 in the axial direction relative to the position where the core metal portion 104a of the worm wheel 104 is fixed. That is, bearing 65 is positioned on the opposite side of the worm wheel 104 in the axial direction from the side where bearing 60 is located, and bearings 60 and 65 are positioned on opposite sides of each other in the axial direction relative to the worm wheel 104.

[0031] The torque sensor 10 includes a magnet 55, a stator 50, and a magnetic collecting yoke 40 (see Figure 3). Of these, the magnet 55 and stator 50 are mounted separately on the input shaft 83 and the output shaft 86, respectively. The magnetic collecting yoke 40 is fixed to the housing 20 by attaching the magnetic collecting yoke assembly 30, which includes the magnetic collecting yoke 40, to the housing 20.

[0032] The torque sensor 10 configured in this way is capable of detecting torque based on the change in magnetism that occurs when the torsion bar 90 twists and the input shaft 83 and output shaft 86 rotate relative to each other.

[0033] Figure 3 is a schematic diagram illustrating the overview of the magnet 55, stator 50, and magnetic collection yoke 40 of the torque sensor 10. The magnet 55 and stator 50 of the torque sensor 10 are attached to the input shaft 83 on one end and to the output shaft 86 on the other. In this embodiment, the magnet 55 is attached to the outer circumferential surface of the input shaft 83, and the stator 50 is attached to the outer circumferential surface of the output shaft 86. The magnet 55 is formed in a substantially cylindrical shape and is an annular permanent magnet in which multiple magnetic poles 56 are arranged alternately in the circumferential direction. In other words, the magnet 55 is a multipole magnet in which different magnetic poles 56, namely N poles 56n and S poles 56s, are arranged alternately in the circumferential direction of the annular magnet 55. In this embodiment, the magnet 55 is an 8-pole multipole magnet.

[0034] The stator 50 has a flange portion 51 and a teeth portion 52. The teeth portion 52 is the part through which the magnetic flux from the magnet 55 flows, and the flange portion 51 is the part that directs the magnetic flux from the magnet 55, which flows from the teeth portion 52 to the stator 50, to the magnetic collecting yoke 40. The flange portion 51 is formed in an annular plate shape with its thickness direction being axial. The teeth portion 52 extends from the inner circumference of the annular flange portion 51 in the axial direction of the flange portion 51, and is formed in a plate shape with its thickness direction being oriented in the radial direction of the flange portion 51. In addition, multiple teeth portions 52 are arranged in the circumferential direction of the flange portion 51 at intervals. The number of teeth portions 52 is the same as the number of magnetic poles 56 that the magnet 55 has.

[0035] The stator 50 formed in this manner has a pair of stators 50 formed of the same shape, namely a first stator 50a and a second stator 50b, each having a flange portion 51 and a tooth portion 52. Specifically, the first stator 50a has an annular first flange portion 51a and a plurality of first tooth portions 52a, and the second stator 50b has an annular second flange portion 51b and a plurality of second tooth portions 52b. The first stator 50a and the second stator 50b are mounted on the same shaft in such a way that both flange portions 51 are coaxially positioned and the flange portions 51 are oriented away from the other stator 50. In this embodiment, both the first stator 50a and the second stator 50b are mounted on the outer circumferential surface of the output shaft 86.

[0036] In other words, the first stator 50a is positioned such that the first teeth portion 52a extends from the first flange portion 51a toward the second stator 50b, and the second stator 50b is positioned such that the second teeth portion 52b extends from the second flange portion 51b toward the first stator 50a. In this configuration, multiple first teeth portions 52a and second teeth portions 52b are provided on the first flange portion 51a and second flange portion 51b at intervals, so that the first stator 50a and the second stator 50b are combined such that the teeth portion 52 of each stator 50 is located in a portion of the circumferential direction where the teeth portion 52 of the other stator 50 is not located.

[0037] The magnet 55 attached to the outer circumferential surface of the input shaft 83 is positioned radially inward of the first stator 50a and the second stator 50b, which are combined in this manner. Furthermore, the magnet 55 and the stator 50 are positioned so that their axial directions coincide with the axial directions of the input shaft 83 and the output shaft 86. For these reasons, the magnet 55 and the stator 50 are mounted on the input shaft 83 and the output shaft 86 in such a position that the outer circumferential surface of the magnet 55 faces the teeth portion 52 of the stator 50. In other words, the stator 50 attached to the output shaft 86 has multiple teeth portion 52 through which magnetic flux from the magnet 55 flows, at a position in the axial direction of the output shaft 86 that is the same as the position of the magnet 55 attached to the input shaft 83, where the connecting portion 83b is connected to the connecting hole 86b and the insertion portion 84 is inserted into the insertion hole 87. The magnet 55 is positioned facing the multiple teeth portion 52 of the stator 50.

[0038] The magnet 55 and the stator 50 are positioned in such a relative position that when torque is transmitted between the input shaft 83 and the output shaft 86 via the torsion bar 90, causing the input shaft 83 and the output shaft 86 to rotate slightly relative to each other, the relative position of the magnet 55 and the stator 50 changes, and consequently, the magnetic flux acting from the magnet 55 to the stator 50 changes.

[0039] Furthermore, a magnetic collecting yoke 40 of the torque sensor 10 is positioned near the stator 50. The magnetic collecting yoke 40 is a component for detecting changes in the magnetic flux acting on the stator 50 from the magnet 55, and is positioned near the flange portion 51 of the stator 50. Since the stator 50 consists of a pair of first stator 50a and second stator 50b, the magnetic collecting yoke 40 also consists of a pair of first magnetic collecting yoke 41 and second magnetic collecting yoke 42. Specifically, the first magnetic collecting yoke 41 is positioned near the first flange portion 51a of the first stator 50a, and the second magnetic collecting yoke 42 is positioned near the second flange portion 51b of the second stator 50b.

[0040] The pair of magnetic collecting yokes 40 are located radially outward from the teeth portion 52 of the stator 50, between the two flange portions 51 of the stator 50, and overlap with the flange portions 51 of the stator 50 with a gap in the axial direction. In other words, the first magnetic collecting yoke 41 is positioned near the side of the first flange portion 51a of the first stator 50a where the second flange portion 51b is located, and the second magnetic collecting yoke 42 is positioned near the side of the second flange portion 51b of the second stator 50b where the first flange portion 51a is located. These magnetic collecting yokes 40 overlap with the flange portions 51 of the stator 50 within a predetermined range in the circumferential direction. By positioning the magnetic collecting yokes 40 near the flange portions 51 in this way, the magnetic collecting yokes 40 can detect changes in the magnetic flux acting on the stator 50 from the magnet 55 when the input shaft 83 and the output shaft 86 rotate relatively small.

[0041] The pair of magnetic collecting yokes 40 may be positioned such that they sandwich the two flange portions 51 of the pair of stators 50 from both sides in the axial direction. In other words, the first magnetic collecting yoke 41 may be positioned near the opposite side of the first flange portion 51a of the first stator 50a from where the second flange portion 51b is located, and the second magnetic collecting yoke 42 may be positioned near the opposite side of the second flange portion 51b of the second stator 50b from where the first flange portion 51a is located. The pair of magnetic collecting yokes 40 may be positioned between the first flange portion 51a and the second flange portion 51b as long as they overlap the flange portions 51 of the stator 50 in a predetermined range in the circumferential direction, and the pair of magnetic collecting yokes 40 may be positioned such that they sandwich the first flange portion 51a and the second flange portion 51b from both sides in the axial direction.

[0042] In this way, by positioning the magnetic collecting yoke 40 near the flange portion 51, the pair of magnetic collecting yokes 40 can detect changes in magnetic flux corresponding to changes in the relative positions of the pair of stators 50 and the magnet 55. In other words, the magnetic collecting yoke 40 can detect changes in the magnetic flux acting from the magnet 55 to the stators 50 when the input shaft 83 and the output shaft 86 rotate relatively slightly.

[0043] Furthermore, a Hall IC 45 is positioned between the two magnetic collecting yokes 40. The Hall IC 45 is positioned between the magnetic collecting yokes 40 at a location away from the portion of the magnetic collecting yoke 40 that is near the flange portion 51 of the stator 50. In other words, the Hall IC 45 is sandwiched between the first magnetic collecting yoke 41 and the second magnetic collecting yoke 42 of the magnetic collecting yoke 40. The Hall IC 45 has a Hall element (not shown) that detects changes in magnetic flux detected by the magnetic collecting yokes 40, and an output circuit (not shown) that converts the output voltage output from the Hall element in response to the change in magnetic flux into a digital electrical signal. As a result, the Hall IC 45 can detect changes in magnetic flux density acting on the two magnetic collecting yokes 40, convert the detected change in magnetic flux density into an electrical signal, and output it as an electrical signal. Note that a magnetic sensor that applies the magnetoresistance effect or the tunnel magnetoresistance effect can be used instead of the Hall IC 45. In short, it is sufficient to output the change in magnetic flux density occurring between the magnetic collecting yokes 40 as an electrical signal.

[0044] As shown in Figure 2, the magnet 55 is attached to the input shaft 83 by a first sleeve 57. The first sleeve 57 is a cylindrical member, and the first sleeve 57 is attached to the input shaft 83 by press-fitting the input shaft 83 into the first sleeve 57. The magnet 55 is fixed to the outer surface of the first sleeve 57, for example, with adhesive, so that the magnet 55 can rotate together with the input shaft 83.

[0045] As shown in Figure 2, the stator 50 is attached to the output shaft 86 by a second sleeve 53 and a carrier 54. The second sleeve 53 is a cylindrical member, and the second sleeve 53 is attached to the output shaft 86 by press-fitting the output shaft 86 into the second sleeve 53. The carrier 54 is a cylindrical member and is integrally formed with the second sleeve 53 by injection molding. Therefore, when the second sleeve 53 is attached to the output shaft 86, the carrier 54 is also attached to the output shaft 86 together with the second sleeve 53.

[0046] The carrier 54, which is attached to the output shaft 86 by the second sleeve 53, is supported by the second sleeve 53 and positioned toward the input shaft 83 from the output shaft 86, and is located radially outward of the input shaft 83. Furthermore, the carrier 54 is positioned in the same axial position as the magnet 55 and is located radially outward of the magnet 55.

[0047] The stator 50 is mounted on the carrier 54, which is arranged in this manner. More specifically, the first stator 50a and the second stator 50b are mounted on the carrier 54 such that their teeth 52 are located on the inside of the carrier 54 in the radial direction, and their flange 51 protrudes from the inside to the outside of the carrier 54 in the radial direction. As a result, both the first stator 50a and the second stator 50b, which are a pair of stators 50, are positioned in the same axial position as the magnet 55, and are positioned radially outward from the magnet 55.

[0048] Furthermore, the first stator 50a and the second stator 50b are attached to a carrier 54 which is integrally formed with the second sleeve 53 that is attached to the output shaft 86, and are therefore able to rotate together with the output shaft 86. In this way, the magnet 55 is fixed to the input shaft 83 and the stator 50 is fixed to the output shaft 86, so the magnet 55 and the stator 50 are positioned inside the housing 20 together with the input shaft 83 and the output shaft 86.

[0049] Figure 4 is an exploded perspective view of the input shaft 83, the output shaft 86, and the torque sensor 10. On the inner circumferential surface of the insertion hole 87 in the output shaft 86, which is the part into which the input shaft 83 is inserted, a surface with irregularities 88 is formed. The surface with irregularities 88 consists of a plurality of protrusions 88b that project inward in the radial direction of the insertion hole 87 and a plurality of recesses 88a that recess outward in the radial direction of the insertion hole 87, which are alternately arranged in the circumferential direction of the insertion hole 87. The length of these protrusions 88b and recesses 88a in the axial direction of the output shaft 86 is the same as the length of the insertion hole 87 in the axial direction.

[0050] On the other hand, the input shaft 83 has an insertion portion 84, which is the part of the input shaft 83 that is inserted into the insertion hole 87 of the output shaft 86. In this embodiment, the insertion portion 84 of the input shaft 83 is positioned adjacent to the connecting portion 83b, which is positioned at the end of the input shaft 83 on the output shaft 86 side, on the opposite side from the side where the output shaft 86 is located. The insertion portion 84 of the input shaft 83 has a set of protrusions 85 formed on its outer circumferential surface, corresponding to the protrusions 88 formed in the insertion hole 87 of the output shaft 86. That is, the protrusions 85 formed on the insertion portion 84 consist of a plurality of recesses 85a that are recessed inward in the radial direction of the insertion portion 84 and a plurality of protrusions 85b that are projected outward in the radial direction of the insertion portion 84, which are alternately arranged in the circumferential direction of the insertion portion 84.

[0051] The number of recesses 85a and protrusions 85b in the uneven portion 85 formed in the insertion portion 84 of the input shaft 83 is the same as the number of recesses 88a and protrusions 88b in the uneven portion 88 formed in the insertion hole 87 of the output shaft 86. In this embodiment, the number of recesses 88a and protrusions 88b formed in the insertion hole 87 of the output shaft 86 is 8 each, and similarly, the number of recesses 85a and protrusions 85b formed in the insertion portion 84 of the input shaft 83 is also 8 each.

[0052] Since the insertion hole 87 of the output shaft 86 has a recessed portion 88 and the insertion portion 84 of the input shaft 83 has a recessed portion 85, when the insertion portion 84 of the input shaft 83 is inserted into the insertion hole 87 of the output shaft 86, the recessed portion 85 of the insertion portion 84 of the input shaft 83 fits into the recessed portion 88 of the insertion hole 87 of the output shaft 86. In other words, when the insertion portion 84 of the input shaft 83 is inserted into the insertion hole 87 of the output shaft 86, the protrusion 85b formed on the insertion portion 84 of the input shaft 83 fits into the recess 88a formed on the insertion hole 87 of the output shaft 86, and the protrusion 88b formed on the insertion hole 87 of the output shaft 86 fits into the recess 85a formed on the insertion portion 84 of the input shaft 83.

[0053] Here, the size of the protrusion 85b formed in the insertion portion 84 of the input shaft 83 in the circumferential direction is smaller than the size of the recess 88a formed in the insertion hole 87 of the output shaft 86 in the circumferential direction. Similarly, the size of the protrusion 88b formed in the insertion hole 87 of the output shaft 86 in the circumferential direction is smaller than the size of the recess 85a formed in the insertion portion 84 of the input shaft 83 in the circumferential direction.

[0054] Therefore, when the insertion portion 84 of the input shaft 83 is inserted into the insertion hole 87 of the output shaft 86, the protrusions and recesses 85 of the input shaft 83 and the protrusions and recesses 88 of the output shaft 86 do not come into contact with each other, and the insertion portion 84 of the input shaft 83 is inserted into the insertion hole 87 of the output shaft 86.

[0055] In other words, when the insertion portion 84 of the input shaft 83 is inserted into the insertion hole 87 of the output shaft 86, the protrusion 85b formed on the insertion portion 84 of the input shaft 83 does not come into contact with the protrusion 88b formed on the insertion hole 87 of the output shaft 86, but is positioned between adjacent protrusions 88b on the uneven portion 88 of the output shaft 86. Therefore, when the insertion portion 84 of the input shaft 83 is inserted into the insertion hole 87 of the output shaft 86, the uneven portion 85 of the input shaft 83 and the uneven portion 88 of the output shaft 86 do not come into contact with each other, and torque is transmitted between the input shaft 83 and the output shaft 86 via the torsion bar 90.

[0056] The uneven surface 85 of the insertion portion 84 of the input shaft 83 and the uneven surface 88 of the insertion hole 87 of the output shaft 86, formed in this manner, do not come into contact during normal steering, but only when the twist angle of the torsion bar 90 exceeds a predetermined angle. In other words, when the twist angle of the torsion bar 90 exceeds a predetermined twist angle, the uneven surface 85 of the insertion portion 84 of the input shaft 83 and the uneven surface 88 of the insertion hole 87 of the output shaft 86 come into contact with each other, thereby preventing the relative difference in rotational angle in the circumferential direction between the input shaft 83 and the output shaft 86 from becoming any larger. This prevents the twist angle of the torsion bar 90 from becoming larger than the twist angle at which the torsion bar 90 is damaged, thereby preventing damage to the torsion bar 90 caused by an excessively large twist angle.

[0057] Next, a method for manufacturing the torque sensor 10 of the steering device 80 according to this embodiment will be described. In the method for manufacturing the torque sensor 10 according to this embodiment, the assembly of the torque sensor 10 is performed using a jig 200 for positioning the stator 50 attached to the output shaft 86 in the circumferential direction.

[0058] Figure 5 is an explanatory diagram illustrating the circumferential positioning of the stator 50 using a jig 200. The jig 200 for positioning the stator 50 in the circumferential direction is formed in a substantially cylindrical shape, and an annular jig magnet 210 is attached to its outer surface. The jig magnet 210 is an annular permanent magnet in which the same number of magnetic poles as the magnet 55 (see Figure 3) attached to the input shaft 83 are arranged alternately in the circumferential direction. That is, the diameter of the jig magnet 210 is the same as the diameter of the magnet 55 attached to the input shaft 83, and the same number of magnetic poles as the number of magnetic poles 56 of the magnet 55 are arranged on the jig magnet 210 at a pitch of the same size as the pitch of the magnetic poles 56 in the circumferential direction of the magnet 55. In this embodiment, since the magnet 55 is an 8-pole multipole magnet, the jig magnet 210 is also an 8-pole multipole magnet, similar to the magnet 55.

[0059] Furthermore, the jig 200 has an insertion portion 201 that can be inserted into the insertion hole 87 of the output shaft 86. The insertion portion 201 is formed in a cylindrical shape, with an outer diameter smaller than the inner diameter at the position of the protrusion 88b of the uneven portion 88 formed in the insertion hole 87 of the output shaft 86.

[0060] The insertion portion 201 of the jig 200 is equipped with a projection 202 that fits into a recess 88a of the uneven portion 88 formed in the insertion hole 87 of the output shaft 86. The projection 202 is located at one point in the circumferential direction of the insertion portion 201. The projection 202 positioned on the insertion portion 201 of the jig 200 has a circumferential width that is approximately the same as the width of the recess 88a formed in the insertion hole 87 of the output shaft 86, and slightly smaller than the width of the recess 88a.

[0061] Furthermore, the height of the projection 202 in the radial direction from the center of the insertion portion 201 is approximately the same as the radius at the position of the recess 88a in the insertion hole 87 of the output shaft 86, and is slightly smaller than the radius at the position of the recess 88a. As a result, the projection 202 positioned on the insertion portion 201 of the jig 200 can fit into the recess 88a of the uneven portion 88 formed in the insertion hole 87 when the insertion portion 201 of the jig 200 is inserted into the insertion hole 87 of the output shaft 86.

[0062] Furthermore, the position of the projection 202 in the circumferential direction relative to the position of the magnetic pole of the jig magnet 210 placed on the jig 200 is the same as the position of one of the multiple protrusions 85b formed on the insertion portion 84 of the input shaft 83 in the circumferential direction relative to the position of the magnetic pole 56 of the magnet 55 placed on the input shaft 83. In other words, the projection 202 is positioned such that its circumferential relative position with respect to the magnetic pole of the jig magnet 210 placed on the jig 200 is the same as the circumferential relative position with respect to the magnetic pole 56 of the magnet 55 placed on the input shaft 83 and one of the protrusions 85b formed on the insertion portion 84 of the input shaft 83.

[0063] In other words, the jig magnet 210 placed in the jig 200 is positioned such that the relative positional relationship in the circumferential direction between the projection 202 placed in the insertion portion 201 of the jig 200 and the magnetic pole of the jig magnet 210 is the same as the relative positional relationship in the circumferential direction between one convex portion 85b formed in the insertion portion 84 of the input shaft 83 and the magnetic pole 56 of the magnet 55 placed on the input shaft 83.

[0064] In this embodiment, the magnet 55 placed on the input shaft 83 is attached to the input shaft 83 in such a circumferential orientation that the boundary between the south pole 56s and the north pole 56n of the magnet 55 is located at the circumferential center of the protrusion 85b formed on the insertion portion 84 of the input shaft 83. Therefore, the jig magnet 210 placed on the jig 200 is attached to the jig 200 in such a circumferential orientation that the boundary between the magnetic poles of the jig magnet 210 is located at the circumferential center of the projection 202 placed on the insertion portion 201 of the jig 200.

[0065] When positioning the stator 50 in the circumferential direction using the jig 200 formed in this manner, the jig 200 is inserted into the inside of the stator 50 in a direction that coincides with the axial direction of the stator 50 and the axial direction of the jig 200. At that time, the stator 50 is positioned so that the side where the second sleeve 53 is located is the side where the insertion portion 201 of the jig 200 is located, and the jig 200 is inserted into the inside of the stator 50 in this manner.

[0066] Once the jig 200 is inserted inside the stator 50, the position of the teeth 52 of the stator 50 in the axial direction is aligned with the position of the jig magnet 210 placed on the jig 200 in the axial direction. As a result, magnetic flux from the jig magnet 210 flows to the teeth 52 of the stator 50, and the stator 50 rotates in the circumferential direction to a position where the magnetic force generated by the magnetic flux of the jig magnet 210 is neutral.

[0067] Specifically, the stator 50, with the jig magnet 210 positioned on the jig 200 on its inner side, will have its circumferential orientation such that the position of the boundary between the multiple magnetic poles of the jig magnet 210 coincides with the position of the center of each tooth portion 52 in the circumferential direction. At this point, the magnetic force from the magnetic flux of the jig magnet 210 becomes neutral, and the rotation of the stator 50 in the circumferential direction stops. In other words, the stator 50's circumferential position is fixed and rotation stops when the position of the center of each tooth portion 52 in the circumferential direction is opposite the position of the boundary between the multiple magnetic poles of the jig magnet 210.

[0068] The jig 200, with the position of the teeth 52 of the stator 50 determined in the circumferential direction by the magnetic force of the jig magnets 210 positioned on the jig 200, and with the orientation of the stator 50 in the circumferential direction determined, inserts the insertion portion 201 of the jig 200 into the insertion hole 87 formed in the output shaft 86. In other words, the jig 200 inserts the insertion portion 201 of the jig 200 into the insertion hole 87 of the output shaft 86 before inserting the insertion portion 84 of the input shaft 83 into the insertion hole 87 of the output shaft 86.

[0069] Since the insertion portion 201 of the jig 200 has a projection 202, when inserting the insertion portion 201 of the jig 200 into the insertion hole 87 of the output shaft 86, the circumferential orientation of the jig 200 is adjusted so that the position of the projection 202 in the circumferential direction matches the position of the recess 88a formed in the insertion hole 87. The jig 200 is inserted into the insertion hole 87 of the output shaft 86 with the position of the projection 202 in the circumferential direction aligned with the position of the recess 88a formed in the insertion hole 87 of the output shaft 86.

[0070] As a result, the jig 200's insertion portion 201 is inserted into the insertion hole 87 of the output shaft 86, with the projection 202 fitting into the recess 88a formed in the insertion hole 87 of the output shaft 86. Since the stator 50 is positioned radially outward of the jig 200, when inserting the insertion portion 201 of the jig 200 into the insertion hole 87 of the output shaft 86, the jig 200 attaches the stator 50, which is positioned around the jig 200, to the output shaft 86, while the insertion portion 201 of the jig 200 is inserted into the insertion hole 87 of the output shaft 86. At that time, the jig 200 pushes the stator 50 against the output shaft 86 while inserting the insertion portion 201 into the insertion hole 87 of the output shaft 86.

[0071] Figure 6 is a cross-sectional view of the main part showing the state in which the insertion portion 201 of the jig 200 is inserted into the insertion hole 87 of the output shaft 86. Since the stator 50 is positioned on the radially outer side of the jig 200 with its circumferential position adjusted, when the insertion portion 201 of the jig 200 is inserted into the insertion hole 87 of the output shaft 86 with the projection 202 fitting into the recess 88a of the output shaft 86, the stator 50 is attached to the output shaft 86 with its circumferential position adjusted by the jig 200. In other words, the stator 50 is attached to the output shaft 86 by the second sleeve 53 fitting onto the outer circumferential surface of the output shaft 86.

[0072] Here, the jig 200 is provided with a push-in portion 205 that contacts the stator 50 around the base end portion of the insertion portion 201. The push-in portion 205 of the jig 200 is formed to protrude from the jig 200 toward the opposite side of the output shaft 86 in the axial direction from the side where the input shaft 83 (see Figure 2) is located, rather than the tip portion 89a which is the end of the output shaft 86 on the side where the insertion hole 87 is located.

[0073] The push-in portion 205 is formed in a cylindrical shape with an inner diameter larger than the outer diameter of the insertion portion 201 and approximately the same size as the diameter of the portion of the output shaft 86 to which the stator 50 is attached. In other words, since the stator 50 is attached to the outer surface of the output shaft 86 by press-fitting the output shaft 86 into the second sleeve 53, the inner diameter of the push-in portion 205 of the jig 200 is approximately the same size as the inner diameter of the second sleeve 53.

[0074] Since the jig 200 is provided with a push-in portion 205, when inserting the insertion portion 201 of the jig 200 into the insertion hole 87 of the output shaft 86 with the stator 50 positioned outside the jig 200, the push-in portion 205 of the jig 200 comes into contact with the second sleeve 53 of the stator 50 on the outer circumferential surface side of the output shaft 86.

[0075] More specifically, the pressing portion 205 of the jig 200 abuts against the end of the second sleeve 53 on the side where the input shaft 83 (see Figure 2) is located in the axial direction. With the pressing portion 205 abutting against the end of the second sleeve 53, inserting the insertion portion 201 of the jig 200 into the insertion hole 87 of the output shaft 86 allows the pressing portion 205 to press the second sleeve 53 in the axial direction, thereby press-fitting the second sleeve 53 into the output shaft 86. The second sleeve 53, which is press-fitted into the output shaft 86, is attached to the outer circumferential surface of the output shaft 86 at a position opposite to the side of the tip portion 89a of the output shaft 86 where the input shaft 83 is located in the axial direction.

[0076] When inserting the insertion portion 201 into the insertion hole 87 of the output shaft 86, the jig 200 presses the stator 50 into the output shaft 86 by bringing the push portion 205 into contact with the second sleeve 53 of the stator 50 and pressing the stator 50 in the axial direction with the push portion 205.

[0077] Figure 7 is a detailed view of the area near the tip 89a of the output shaft 86. When inserting the insertion portion 201 of the jig 200 into the insertion hole 87 of the output shaft 86, the second sleeve 53 of the stator 50 is pressed with the push portion 205 of the jig 200 during insertion. Therefore, a tapered portion 89b and a sliding contact portion 89c are formed on the outer circumferential surface of the output shaft 86 near the tip 89a, which is the end of the output shaft 86 on the side where the insertion hole 87 is located, to facilitate pressing by the push portion 205. Specifically, the outer circumferential surface of the tapered portion 89b is inclined in a direction such that the diameter increases as it moves away from the tip 89a in the axial direction from the tip 89a of the output shaft 86.

[0078] Furthermore, the sliding contact portion 89c is located in the axial direction of the output shaft 86 between the press-fit portion 89d, which is the portion of the output shaft 86 that is press-fitted into the second sleeve 53 of the stator 50 on the outer circumferential surface of the output shaft 86, and the tapered portion 89b. The diameter of the sliding contact portion 89c is larger than the diameter of the tapered portion 89b, and the outer circumferential surface is inclined in a direction in which the diameter increases from the side where the tapered portion 89b is located to the side where the press-fit portion 89d is located, in the axial direction of the output shaft 86. In addition, the angle of inclination of the sliding contact portion 89c with respect to the axial direction of the output shaft 86 is smaller than the angle of inclination of the tapered portion 89b with respect to the axial direction, and the inclination of the sliding contact portion 89c is gentler compared to the tapered portion 89b.

[0079] When inserting the insertion portion 201 of the jig 200 into the insertion hole 87 of the output shaft 86, the pushing portion 205 of the jig 200 is positioned radially outward from the tip portion 89a of the output shaft 86, and the pushing portion 205 of the jig 200 is placed over the outer circumferential surface near the tip portion 89a of the output shaft 86. At this time, since a tapered portion 89b is formed near the tip portion 89a of the output shaft 86, the jig 200 is guided by the tapered portion 89b, allowing the pushing portion 205 to be smoothly positioned radially outward from the outer circumferential surface near the tip portion 89a of the output shaft 86.

[0080] Once the push-in portion 205 of the jig 200 is placed over the outer circumferential surface near the tip portion 89a of the output shaft 86, the insertion portion 201 of the jig 200 is further inserted into the insertion hole 87 of the output shaft 86. As a result, the push-in portion 205 of the jig 200 moves to the side where the press-fit portion 89d is located on the outer circumferential surface of the output shaft 86. However, a sliding contact portion 89c is formed between the tapered portion 89b and the press-fit portion 89d on the outer circumferential surface of the output shaft 86. Therefore, when inserting the insertion portion 201 of the jig 200 into the insertion hole 87 of the output shaft 86, the push-in portion 205 comes into contact with the sliding contact portion 89c and slides against it, and moves axially while its tilt is adjusted by the sliding contact portion 89c.

[0081] As a result, the jig 200 can position the push-in portion 205 radially outward from the outer circumferential surface near the tip portion 89a of the output shaft 86 without tilting the push-in portion 205 relative to the output shaft 86. When the push-in portion 205 presses the second sleeve 53 of the stator 50 into the press-fit portion 89d of the output shaft 86 in the axial direction, the pressing force can be applied evenly to the second sleeve 53 in the circumferential direction. Therefore, the second sleeve 53 of the stator 50 can be press-fitted into the output shaft 86 without tilting it relative to the axial direction of the output shaft 86, and the stator 50 can be properly attached to the outer circumferential surface of the output shaft 86.

[0082] The stator 50 has its circumferential position of the teeth portion 52 relative to the projection portion 202 determined by the jig magnet 210 placed on the jig 200, and the jig 200 is inserted into the insertion hole 87 of the output shaft 86 with the insertion portion 201 of the jig 200 facing the recess 88a formed in the insertion hole 87 of the output shaft 86.

[0083] As a result, the stator 50, which is attached to the outer surface of the output shaft 86 using the jig 200, is attached to the outer surface of the output shaft 86 in an orientation in which the jig magnet 210 and projection 202 of the jig 200 are positioned circumferentially with respect to the recess 88a formed in the insertion hole 87 of the output shaft 86. By attaching the stator 50 to the output shaft 86 using the jig 200 in this way, the position of the teeth portion 52 in the circumferential direction of the output shaft 86 is adjusted by the magnetic flux of the jig magnet 210 attached to the jig 200 inserted into the insertion hole 87 of the output shaft 86 and the projection 202 that fits into the recess 88a of the insertion hole 87, thereby attaching the stator 50 to the output shaft 86.

[0084] After adjusting the circumferential position of the teeth portion 52 with respect to the recess 88a formed in the insertion hole 87 of the output shaft 86, and after positioning the stator 50 on the output shaft 86, the jig 200 is removed from the insertion hole 87 of the output shaft 86, and the input shaft 83 is connected to the output shaft 86. In other words, after removing the jig 200 from the insertion hole 87 of the output shaft 86, the connecting portion 83b of the input shaft 83 is connected to the connecting hole 86b of the output shaft 86, and the insertion portion 84 of the input shaft 83 is connected to the insertion hole 87 of the output shaft 86. In this case, the input shaft 83 is connected to the output shaft 86 with the magnet 55 attached to its outer circumferential surface.

[0085] At that time, since the insertion portion 84 of the input shaft 83 has a grooved portion 85 formed thereon, the circumferential orientation of the input shaft 83 is set so that it can be inserted into the insertion hole 87 of the output shaft 86 where the grooved portion 88 is formed, and the insertion portion 84 of the input shaft 83 is inserted into the insertion hole 87 of the output shaft 86.

[0086] In other words, the input shaft 83 is inserted into the insertion hole 87 of the output shaft 86 with the orientation such that the position of the recess 85a of the insertion portion 84 of the input shaft 83 in the circumferential direction is the same as the position of the protrusion 88b of the insertion hole 87 of the output shaft 86, and the position of the protrusion 85b of the insertion portion 84 of the input shaft 83 in the circumferential direction is the same as the position of the recess 88a of the insertion hole 87 of the output shaft 86.

[0087] The magnet 55 positioned on the input shaft 83 is attached to the input shaft 83 with the position of its magnetic pole 56 in the circumferential direction relative to the uneven portion 85 of the insertion portion 84 being in a predetermined position. The stator 50 positioned on the output shaft 86 is attached to the output shaft 86 with the position of its teeth portion 52 in the circumferential direction relative to the uneven portion 88 of the insertion hole 87 being adjusted by a jig 200 having a projection 202 and a jig magnet 210.

[0088] Therefore, when the insertion portion 84 of the input shaft 83 is inserted into the insertion hole 87 of the output shaft 86 by aligning the circumferential orientation of the uneven portion 85 formed on the insertion portion 84 of the input shaft 83 with the circumferential orientation of the uneven portion 88 formed on the insertion hole 87 of the output shaft 86, the circumferential position of the teeth portion 52 of the stator 50 arranged on the output shaft 86 becomes suitable for the circumferential position of the magnetic pole 56 of the magnet 55 arranged on the input shaft 83, and the input shaft 83 and the output shaft 86 are connected. Specifically, the input shaft 83 and the output shaft 86 are connected in a direction in which the boundary between the magnetic poles 56 of the magnet 55 arranged on the input shaft 83 and the circumferential center position of the teeth portion 52 of the stator 50 arranged on the output shaft 86 coincide in the circumferential direction.

[0089] During the manufacturing of the torque sensor 10, when connecting the input shaft 83 and the output shaft 86 in this manner, the torsion bar 90 is also connected. In this embodiment, before connecting the input shaft 83 and the output shaft 86, the end of the torsion bar 90 is press-fitted into the through hole 86a formed in the output shaft 86. When connecting the input shaft 83 and the output shaft 86, the other end of the torsion bar 90 is inserted into the insertion hole 83a formed in the input shaft 83 while connecting them. After connecting the input shaft 83 and the output shaft 86, a pin 98 for fixing the torsion bar 90 to the input shaft 83 is inserted into the through hole formed in the input shaft 83 and the through hole formed in the torsion bar 90. In this way, the torsion bar 90 is fixed to the input shaft 83 by the pin 98, and the input shaft 83 and the output shaft 86 are connected via the torsion bar 90.

[0090] Next, the operation of the steering device 80 will be explained. 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 92, and from the intermediate shaft 92 to the pinion gear 95a via the pinion shaft 94. As a result, the steering gear 95, which has the pinion gear 95a, converts the rotational motion transmitted from the pinion gear 95a into linear motion of the rack bar 95b, and operates the tie rod 96.

[0091] Furthermore, the steering device 80 according to this embodiment has an electric motor 101 that generates auxiliary steering torque to assist the driver's steering. The electric motor 101 generates auxiliary steering torque based on the steering torque detected by a torque sensor 10 positioned between the input shaft 83 and the output shaft 86 of the steering shaft 82.

[0092] The torque sensor 10 detects the steering torque applied from the steering wheel 81 to the steering shaft 82 based on the angle of relative rotation when the input shaft 83 and the output shaft 86 rotate relative to each other. That is, since the input shaft 83 and the output shaft 86 are connected via a torsion bar 90, when steering torque is applied to the input shaft 83 of the steering shaft 82, the steering torque is transmitted between the input shaft 83 and the output shaft 86 via the torsion bar 90. At that time, the torsion bar 90 twists slightly, causing the input shaft 83 and the output shaft 86 to rotate relative to each other.

[0093] The torque sensor 10 has a magnet 55 attached to the input shaft 83 and a stator 50 attached to the output shaft 86. Therefore, when the input shaft 83 and the output shaft 86 rotate relative to each other, the magnet 55 and stator 50 of the torque sensor 10 also rotate relative to each other. The angle of relative rotation between the magnet 55 and the stator 50 increases as the steering torque acting between the input shaft 83 and the output shaft 86 increases.

[0094] When the magnet 55 and the stator 50 rotate relative to each other, the magnetic flux acting from the magnet 55 to the stator 50 changes. The magnetic collecting yoke 40, positioned near the stator 50, is capable of detecting changes in the magnetic flux acting from the magnet 55 to the stator 50. Therefore, when the magnet 55 and the stator 50 rotate relative to each other due to the relative rotation of the input shaft 83 and the output shaft 86, the magnetic collecting yoke 40, positioned near the stator 50, can detect changes in the magnetic flux acting from the magnet 55 to the stator 50.

[0095] In other words, the magnet 55 and the stator 50 are assembled by the manufacturing method according to this embodiment so that the circumferential position of the teeth portion 52 of the stator 50 is positioned in a suitable location relative to the circumferential position of the magnetic pole 56 of the magnet 55. Therefore, the torque sensor 10 can appropriately detect the change in magnetic flux acting on the stator 50 when the relative position of the magnet 55 and the stator 50 changes, using the magnetic collecting yoke 40.

[0096] Thus, the magnetic flux acting from the magnet 55 on the stator 50, as detected by the magnetic collecting yoke 40, changes according to the angle of relative rotation between the magnet 55 and the stator 50. The Hall IC 45 detects the magnetic flux that changes according to the angle of relative rotation between the magnet 55 and the stator 50, as detected by the magnetic collecting yoke 40, using its Hall element, and converts it into an electrical signal in its output circuit, which is then transmitted to the ECU 100 as an output signal from the torque sensor 10. In other words, the torque sensor 10 detects the steering torque applied to the input shaft 83 by detecting the change in magnetic flux acting from the magnet 55 on the stator 50 using the magnetic collecting yoke 40 and the Hall IC 45, and transmits the detected steering torque as an electrical signal to the ECU 100.

[0097] The ECU 100 operates the electric motor 101 based on the electrical signal transmitted from the torque sensor 10, generating auxiliary steering torque in the electric motor 101. 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 acting between the input shaft 83 and the output shaft 86. Therefore, the ECU 100 uses the electrical signal transmitted from the Hall IC 45 of the torque sensor 10 as information that changes according to the steering torque acting on the input shaft 83 and the output shaft 86, and adjusts the power value supplied to the electric motor 101 based on the electrical signal transmitted from the Hall IC 45, generating auxiliary steering torque in the electric motor 101.

[0098] Specifically, the ECU 100 acquires a steering torque signal from the torque sensor 10, a vehicle speed signal from the vehicle speed sensor 105, and operational information of the electric motor 101 from a rotation detection device provided on the electric motor 101. Based on this operational information, the steering torque, and the vehicle speed signal, the ECU 100 generates auxiliary steering torque in the electric motor 101. The auxiliary steering torque generated by the electric motor 101 is transmitted to the output shaft 86 of the steering shaft 82 via the worm 103 and worm wheel 104. As a result, the steering force applied by the driver to the steering wheel 81 is assisted by the auxiliary steering torque generated by the electric motor 101.

[0099] As described above, in the manufacturing method of the torque sensor 10 according to this embodiment, before inserting the input shaft 83 into the insertion hole 87 of the output shaft 86, a jig 200 having a jig magnet 210 and a projection 202 is inserted into the insertion hole 87 of the output shaft 86 to attach the stator 50 to the output shaft 86. Therefore, the position of the teeth portion 52 of the stator 50 in the circumferential direction can be adjusted by the magnetic flux of the jig magnet 210 to attach the stator 50 to the output shaft 86. As a result, when manufacturing multiple torque sensors 10, the circumferential positioning of the stator 50 in each torque sensor 10 can be performed using the jig 200 without having to perform positioning embossing on each stator 50 or form grooves corresponding to the embossing on each output shaft 86. Consequently, the processing required to position the stator 50 in the circumferential direction during the manufacturing of the torque sensor 10 can be reduced, simplifying the manufacturing process. As a result, manufacturing costs can be reduced.

[0100] Furthermore, the jig 200 has a pressing portion 205 that contacts the stator 50. When inserting the jig 200 into the insertion hole 87 of the output shaft 86, the pressing portion 205 is brought into contact with the stator 50, and the stator 50 is pressed axially by the pressing portion 205, thereby press-fitting the stator 50 into the output shaft 86. This allows the stator 50, whose position in the circumferential direction has been adjusted by the jig magnet 210, to be press-fitted into the output shaft 86 by the jig 200 while maintaining the orientation of the stator 50 in the circumferential direction. Therefore, the process of positioning the stator 50 in the circumferential direction and attaching the stator 50 to the output shaft 86 can be simplified. As a result, manufacturing costs can be reduced.

[0101] [Differentiation] In the embodiment described above, one projection 202 is provided on the insertion portion 201 of the jig 200, but there may be multiple projections 202 provided on the insertion portion 201 of the jig 200. The number of projections 202 provided on the insertion portion 201 of the jig 200 does not matter, as long as they are configured to allow the stator 50, whose circumferential position has been adjusted by the jig magnet 210, to be positioned and attached to the output shaft 86 by fitting the projections 202 into recesses 88a formed in the insertion hole 87 of the output shaft 86.

[0102] Furthermore, in the embodiment described above, the magnet 55 is a multi-pole magnet with 8 pole pairs, and the number of recesses 88a and protrusions 88b formed in the insertion hole 87 of the output shaft 86, and the number of recesses 85a and protrusions 85b formed in the insertion portion 84 of the input shaft 83 are each 8, but these may be provided in other numbers.

[0103] Furthermore, in the embodiment described above, the torsion bar 90 is fixed to the input shaft 83 by a pin 98 and to the output shaft 86 by press-fitting into the through hole 86a. However, the fixing of the input shaft 83 and the output shaft 86 to the torsion bar 90 may be in other forms. For example, the torsion bar 90 may be fixed to the input shaft 83 by press-fitting and to the output shaft 86 by a pin 98.

[0104] Furthermore, in the embodiment described above, the first axis is the input axis 83 and the second axis is the output axis 86, but the first axis may be something other than the input axis 83, and the second axis may be something other than the output axis 86. For example, the first axis may be the output axis 86, and the second axis may be the input axis 83. In this case, an insertion hole is formed in the second axis, the input axis 83, into which the first axis, the output axis 86, is inserted, the magnet 55 of the torque sensor 10 is attached to the first axis, the output axis 86, and the stator 50 of the torque sensor 10 is attached to the second axis, the input axis 83. When the first axis and the second axis are configured in this way, the jig 200 to which the jig magnet 210 is attached is inserted into the insertion hole of the second axis, the input axis 83, and the stator 50 attached to the input axis 83 adjusts the position of the teeth portion 52 in the circumferential direction by the magnetic flux of the jig magnet 210 attached to the jig 200 inserted into the insertion hole. In other words, the insertion hole is formed in the shaft of the first and second shafts on which the stator 50 is attached, and the position of the teeth portion 52 in the circumferential direction is adjusted by inserting the jig 200 into the insertion hole formed in the shaft on which the stator 50 is attached, and using the magnetic flux of the jig magnet 210 on the jig 200. Thus, the first and second shafts may be in forms other than those described above.

[0105] Furthermore, in the embodiment described above, the steering device 80 is a column-assist type electric power steering device in which assist force is applied to the steering shaft 82, but the steering device 80 is not limited to this. The steering device 80 may be, for example, a single-pinion assist type in which assist force is applied to the pinion gear 95a, or a dual-pinion type electric power steering device that includes a second pinion gear (not shown) that meshes with the rack bar 95b at a different position from the pinion gear 95a, and assist force is applied to the second pinion gear. Alternatively, the steering device 80 may be a rack-assist type electric power steering device that applies assist force to the rack bar 95b without going through a pinion, such as a ball screw type in which assist force is applied to the rack bar 95b by a ball screw. The steering device 80 is not limited to any type of electric power steering device as long as a magnet 55 and a stator 50 are used in the torque sensor 10 that detects torque.

[0106] While preferred embodiments of this disclosure have been described above, this disclosure is not limited to those described in the embodiments described above. The configurations described as embodiments and modifications may be combined as appropriate. [Explanation of symbols]

[0107] 10 Torque Sensor 20 Housing 21 Housing 1 25 Second Housing 30 Magnetic Collecting Yoke Assembly 40 Magnetic Collecting Yoke 41. First magnetic collecting yoke 42. Second magnetic yoke 45 Hole IC 50 staters 50a First Stator 50b Second State 51 Flange section 51a First flange section 51b Second flange section 52 Teeth section 52a First Teeth Section 52b Second Teeth Section 53 Sleeve 2 54 Carriers 55 Magnets 56 magnetic pole 56s S pole 56n N pole 57 First Sleeve 60, 65 bearings 80 Steering gear 81 Steering Wheel 82 Steering shaft 83 Input axis 83a Insertion hole 83b Connecting part 84 Insertion section 85 Uneven part 85a recess 85b protrusion 86 Output shaft 86a Through hole 86b Connection hole 87 Insertion hole 88 Uneven part 88a recess 88b protrusion 89a Tip 89b Tapered section 89c Sliding contact part 89d Press-fit section 90 Torsion Bar 91, 93 Universal joint 92 Intermediate shaft 94 Pinion Shaft 95 Steering gear 95a Pinion Gear 95b Rack Bar 96 Tie Rod 98 pins 100 ECU 101 Electric Motor 102 Reducer 103 Warm 104 Worm Wheel 104a Core metal part 104b Wheel teeth 105 Vehicle speed sensor 108 Ignition Switch 109 Power supply 200 jigs 201 Insertion section 202 Protrusion 205 Push-in part 210 Magnets for jigs

Claims

1. The first axis and, A ring-shaped permanent magnet is attached to the outer surface of the first shaft, and a plurality of magnetic poles are arranged alternately in the circumferential direction. A second shaft having an insertion hole into which the first shaft is inserted, and having a plurality of protrusions projecting inward in the radial direction of the insertion hole and a plurality of recesses recessing outward in the radial direction arranged alternately in the circumferential direction of the insertion hole on the inner circumferential surface of the insertion hole, A stator having multiple teeth attached to the outer circumferential surface of the second shaft, where the position of the second shaft in the axial direction is the same as that of the permanent magnet attached to the first shaft inserted into the insertion hole, through which magnetic flux from the permanent magnet flows; A method for manufacturing a torque sensor comprising: Before inserting the first shaft into the insertion hole of the second shaft, a jig is inserted into the insertion hole, the jig having a cylindrical shape with an annular jig magnet attached to its outer surface, the same number of magnetic poles as the permanent magnet arranged alternately in the circumferential direction, and a projection that fits into the recess formed in the insertion hole of the second shaft. A method for manufacturing a torque sensor, wherein the stator is attached to the second shaft by adjusting the position of the teeth portion in the circumferential direction of the second shaft using the magnetic flux of the jig magnet attached to the jig inserted into the insertion hole.

2. The jig has a pressing portion that contacts the stator, A method for manufacturing a torque sensor according to claim 1, wherein when inserting the jig into the insertion hole of the second shaft, the pressing portion is brought into contact with the stator and the stator is pressed in the axial direction by the pressing portion, thereby press-fitting the stator into the second shaft.

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