Torque sensor and method of manufacturing a magnet assembly

Abstract

In the torque sensor (1), the sleeve (21) is a ring-shaped member mounted to the first rotating member. The intermediate member (26) is a ring-shaped member disposed on the outer circumferential surface of the sleeve (21). The magnet (25) is a ring-shaped member disposed on the outer circumferential surface of the intermediate member (26). The yoke (35) is mounted to the second rotating member and faces the magnet (25) in the radial direction. The rotating member connecting portion (211) of the sleeve (21) is cylindrical and contacts the first rotating member. The intermediate member connecting portion (215) is located at a position axially offset with respect to the rotating member connecting portion (211). The intermediate member (26) includes a thin-walled portion (261) and a thick-walled portion (263) having a wall thickness greater than that of the thin-walled portion (261). The inner circumferential surface of the thin-walled portion (261) and the inner circumferential surface of the thick-walled portion (263) contact the intermediate member connecting portion (215).

Description

Technical Field

[0001] This invention relates to a torque sensor and a method for manufacturing a magnet assembly. Background Technology

[0002] Electric power steering systems installed in vehicles include torque sensors for detecting steering torque. The torque sensor's output changes in response to the relative rotation of the input and output shafts, which are connected by a torsion bar. The ECU (Electronic Control Unit) controls the motor based on information obtained from the torque sensor, and the torque generated by the motor assists steering. For example, Patent Document 1 describes an example of a torque sensor. In the torque sensor of Patent Document 1, a magnet is mounted on the steering shaft using a sleeve. The sleeve has a small-diameter portion that is pressed into the steering shaft and a large-diameter portion that holds the magnet in place using an adhesive. Therefore, when the sleeve is pressed into the steering shaft, deformation of the large-diameter portion holding the magnet can be suppressed. As a result, the distance between the magnet and the yoke is less likely to deviate from the design value, thereby suppressing a decrease in the detection accuracy of the torque sensor.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: International Publication No. 2019 / 059230 Summary of the Invention

[0006] The problem the invention aims to solve

[0007] In addition, in Patent Document 1, since the magnet is mounted on the sleeve using an adhesive, when producing torque sensors, the magnet needs to be aligned with the sleeve before being mounted on it, which presents a problem of relatively complicated production process.

[0008] The present invention was made in view of the above-mentioned problems, and its object is to provide a method for manufacturing a torque sensor and a magnet assembly that can suppress the reduction of detection accuracy and simplify the production process.

[0009] Solution for solving the problem

[0010] To achieve the above objectives, a torque sensor according to one embodiment of the present invention includes: an annular sleeve mounted on a first rotating member; an annular intermediate member disposed on the outer peripheral surface of the sleeve; an annular magnet disposed on the outer peripheral surface of the intermediate member; and a magnetic yoke mounted on a second rotating member rotating relative to the first rotating member, and facing the magnet radially upward in a direction orthogonal to the central axis of the sleeve. The sleeve includes: a rotating member connecting portion, which is cylindrical and contacts the first rotating member; and an intermediate member connecting portion, which is cylindrical with an outer diameter larger than that of the rotating member connecting portion, and located axially offset relative to the rotating member connecting portion from the central axis. The intermediate member includes a thin-walled portion and a thick-walled portion with a wall thickness greater than that of the thin-walled portion, the inner peripheral surfaces of the thin-walled portion and the thick-walled portion contacting the intermediate member connecting portion.

[0011] By bringing the connecting portion of the rotating member into contact with the first rotating member, deformation of the connecting portion of the intermediate member holding the magnet can be suppressed when the sleeve is pressed into the first rotating member. Therefore, the distance between the magnet and the yoke is less likely to deviate from the design value. Thus, the torque sensor can suppress the reduction in detection accuracy. Furthermore, by including a thin-walled portion and a thick-walled portion in the intermediate member, the thick-walled portion hooks onto the outer circumferential surface of the sleeve. Relative movement of the intermediate member and the sleeve in the axial and circumferential directions is suppressed. Additionally, in the production of the torque sensor of the present invention, after the intermediate member is formed on the outer circumference of the sleeve, the magnet is formed on the outer circumference of the intermediate member; therefore, it is not necessary to position the magnet relative to the sleeve, thus simplifying the production process.

[0012] As a desired technical solution for torque sensors, the outer diameter of the intermediate component connection is larger than the outer diameter of the rotating component connection.

[0013] Therefore, the stress generated at the rotating member connection during the pressing of the sleeve into the input shaft is absorbed by the deformation of the enlarged portion located between the rotating member connection and the intermediate member connection. Thus, the transmission of stress generated during the pressing of the sleeve to the intermediate member connection can be suppressed.

[0014] As a desired technical solution for torque sensors, the outer diameter of the intermediate component connection is smaller than the outer diameter of the rotating component connection.

[0015] Therefore, compared to the case where the outer diameter of the intermediate component connection is larger than the outer diameter of the rotating component connection, the magnet can be positioned further inward in the radial direction. This allows for the miniaturization of the torque sensor.

[0016] As a desired technical solution for torque sensors, the outer diameter of the intermediate component connection is the same as the outer diameter of the rotating component connection.

[0017] Therefore, compared to the case where the outer diameter of the intermediate component connection is larger than the outer diameter of the rotating component connection, the magnet can be positioned further inward in the radial direction. This allows for miniaturization of the torque sensor. Furthermore, the shape of the sleeve becomes simpler, thus simplifying the sleeve manufacturing process.

[0018] As a desired technical solution for a torque sensor, the magnet includes a tapered portion with a reduced wall thickness at one end facing the axial direction, the tapered portion facing the rotating member connection in the radial direction.

[0019] To reduce the stress acting on the magnet when the connecting portion of the rotating member is pressed into the first rotating member, a radial gap is provided between the magnet and the connecting portion of the rotating member. To form this gap, a mold needs to be inserted into the gap during magnet formation. In the torque sensor of the present invention, by including a tapered portion in the magnet, the mold used during magnet formation is easily removed.

[0020] As a desired technical solution for a torque sensor, the intermediate component includes an even number of thin-walled portions or an even number of thick-walled portions, which, when viewed from the axial direction, are equally spaced along the circumferential direction centered on the central axis.

[0021] The protrusions or recesses of the sleeve corresponding to the thin-walled or thick-walled portions are formed, for example, by stamping. An even number of protrusions or recesses are arranged at equal intervals in the circumferential direction, thus facilitating the stamping of the sleeve. Furthermore, forming the protrusions or recesses by stamping is preferred when the sleeve is a thin-walled cylindrical shape. By making the sleeve shape thinner, the torque sensor can be made lighter.

[0022] As a desired technical solution for torque sensors, in a cross-section including the central axis, the thick-walled portion is located axially between a portion of the thin-walled portion and another portion of the thin-walled portion.

[0023] Assuming that the thick-walled portion is positioned at the axial end of the intermediate member, in order to prevent the intermediate member from moving relative to the sleeve, thick-walled portions need to be provided at both ends of the intermediate member. That is, two rows of thick-walled portions are required. In contrast, in the torque sensor of the present invention, it is sufficient to prevent the intermediate member from moving relative to the sleeve if there is at least one thick-walled portion. The torque sensor of the present invention reduces the number of required thick-walled portions.

[0024] As a desired technical solution for a torque sensor, the intermediate component connecting portion includes a recess on the outer peripheral surface and a protrusion on the inner peripheral surface at a position corresponding to the recess.

[0025] Therefore, concave and convex portions can be easily formed by stamping. The torque sensor of the present invention can easily perform the process of forming the portion for hooking the thick-walled portion in the sleeve.

[0026] As a desired technical solution for a torque sensor, the protrusion is positioned radially outward from the inner circumferential surface of the rotating member connection.

[0027] Therefore, when the sleeve is pressed into the first rotating member, the protrusion does not contact the first rotating member. Consequently, no force is applied directly from the first rotating member to the connection portion of the intermediate member. The torque sensor of the present invention can reduce the stress generated in the intermediate member and the magnet.

[0028] As a desirable technical solution for torque sensors, the radial spacing between the magnet and the yoke is smaller than the difference in wall thickness between the thin-walled portion and the thick-walled portion.

[0029] Therefore, it is assumed that even if an abnormality occurs in the magnet causing it to move towards the yoke, the thick-walled portion will remain hooked onto the sleeve. Thus, the magnet will not detach from the sleeve. The torque sensor of this invention reduces the possibility of it becoming unoutputtable.

[0030] As a desired technical solution for a torque sensor, the intermediate component is resin, the magnet contains magnetic powder and resin, and the coefficient of linear expansion of the intermediate component is smaller than the coefficient of linear expansion of the resin in the magnet.

[0031] Therefore, the torque sensor of the present invention can reduce the stress generated in the intermediate component and the magnet even when the intermediate component and the magnet are exposed to an environment with temperature changes.

[0032] As a desired technical solution for a torque sensor, the intermediate component is resin, the magnet contains magnetic powder and resin, and the resin of the intermediate component and the resin of the magnet are the same material.

[0033] Therefore, the torque sensor of the present invention can reduce the stress generated in the intermediate component and the magnet even when the intermediate component and the magnet are exposed to an environment with temperature changes.

[0034] To achieve the above objectives, one method for manufacturing a magnet assembly according to the present invention is a method for manufacturing a magnet assembly for a torque sensor. The torque sensor includes: an annular sleeve for mounting on a first rotating member; an annular intermediate member disposed on the outer peripheral surface of the sleeve; and an annular magnet disposed on the outer peripheral surface of the intermediate member. The sleeve includes: a rotating member connecting portion, which is cylindrical; and an intermediate member connecting portion, which is cylindrical with an outer diameter larger than that of the rotating member connecting portion, and located relative to the rotating member connecting portion. The manufacturing method of the magnet assembly, which is axially offset from the central axis of the sleeve, includes: a first mold configuration step, in which a first mold is configured outside the intermediate member connecting portion; an intermediate member forming step, in which an intermediate member including a thin-walled portion and a thick-walled portion having a wall thickness greater than that of the thin-walled portion is formed by filling the first mold with resin; a second mold configuration step, in which a second mold is configured outside the intermediate member; and a magnet forming step, in which the magnet is formed by filling the second mold with resin containing magnet powder.

[0035] Therefore, the resin-containing intermediate component and the magnet are firmly attached to each other. Thus, relative movement between the intermediate component and the magnet in the axial and circumferential directions is suppressed. Furthermore, the intermediate component includes a thin-walled portion and a thick-walled portion. Thus, the thick-walled portion hooks onto the outer circumferential surface of the sleeve. Relative movement between the intermediate component and the sleeve in the axial and circumferential directions is suppressed. Therefore, the possibility of magnet positional displacement can be reduced. Therefore, the manufacturing method of the magnet assembly of the present invention can further suppress the reduction in detection accuracy.

[0036] A desired technical solution for manufacturing a magnet assembly includes a sleeve machining process that plastically deforms the outer peripheral surface of the intermediate component connecting portion in a radial direction orthogonal to the central axis before the first mold configuration step.

[0037] Therefore, the manufacturing method of the magnet assembly of the present invention can, for example, easily form the portion for hooking the thick-walled portion in the sleeve by stamping.

[0038] As a desired technical solution for manufacturing magnet components, injection molding is used in the intermediate component forming step and the magnet forming step.

[0039] Therefore, the manufacturing method of the magnet assembly of the present invention can more easily form intermediate components and magnets.

[0040] The effects of the invention

[0041] The manufacturing method of the torque sensor and magnet assembly of the present invention can suppress the reduction of detection accuracy and simplify the production process. Attached Figure Description

[0042] Figure 1 This is a schematic diagram of the steering device in this embodiment.

[0043] Figure 2 This is a perspective view of the steering device in this embodiment.

[0044] Figure 3 This is an exploded perspective view of the steering device in this embodiment.

[0045] Figure 4 This is a cross-sectional view of the steering device in this embodiment.

[0046] Figure 5 yes Figure 4 A magnified view of a specific part.

[0047] Figure 6 Therefore with Figure 4 Cross-sectional views obtained by cutting the steering device of this embodiment with different planes.

[0048] Figure 7 yes Figure 6 A magnified view of a specific part.

[0049] Figure 8 This is a cross-sectional view of the periphery of the magnet assembly in this embodiment.

[0050] Figure 9 yes Figure 8 A magnified view of a specific part.

[0051] Figure 10 This is an exploded perspective view showing the magnet assembly and yoke of this embodiment.

[0052] Figure 11 This is an exploded perspective view of the magnet assembly of this embodiment.

[0053] Figure 12 This is a schematic diagram illustrating the manufacturing method (plastic deformation process of the outer peripheral surface) of the magnet assembly according to this embodiment.

[0054] Figure 13 This is a schematic diagram illustrating the manufacturing method (first mold configuration step) of the magnet assembly according to this embodiment.

[0055] Figure 14 This is a schematic diagram illustrating the manufacturing method (intermediate component filling process) of the magnet assembly according to this embodiment.

[0056] Figure 15This is a schematic diagram illustrating the manufacturing method of the magnet assembly of this embodiment (first mold removal process).

[0057] Figure 16 This is a schematic diagram illustrating the manufacturing method (second mold configuration step) of the magnet assembly according to this embodiment.

[0058] Figure 17 This is a schematic diagram illustrating the manufacturing method (magnet filling process) of the magnet assembly according to this embodiment.

[0059] Figure 18 This is a schematic diagram illustrating the manufacturing method of the magnet assembly of this embodiment (second mold removal process).

[0060] Figure 19 This is a cross-sectional view of the periphery of the magnet assembly in the first modified example.

[0061] Figure 20 This is a cross-sectional view of the periphery of the magnet assembly in the second variation. Detailed Implementation

[0062] The present invention will now be described in detail with reference to the accompanying drawings. Furthermore, the embodiments described below (hereinafter referred to as "implementations") do not limit the present invention. Additionally, the constituent elements of the following embodiments include elements readily conceived by those skilled in the art and substantially the same elements, elements within the so-called equivalent scope. Moreover, the constituent elements disclosed in the following embodiments can be appropriately combined.

[0063] (Implementation Method)

[0064] Figure 1 This is a schematic diagram of the steering device in this embodiment. Figure 2 This is a perspective view of the steering device in this embodiment. Figure 3 This is an exploded perspective view of the steering device in this embodiment. Figure 4 This is a cross-sectional view of the steering device in this embodiment.

[0065] like Figure 1 As shown, the steering device 80, in the order of force transmission from the operator, includes a steering wheel 81, a steering shaft 82, a steering force assist mechanism 83, a universal joint 84, an intermediate shaft 85, and a universal joint 86, and the steering device 80 engages with a pinion shaft 87. In the following description, the front of the vehicle equipped with the steering device 80 will be referred to as the front, and the rear of the vehicle will be referred to as the rear. Figure 2 As shown, the steering force assist mechanism 83 is located near the steering wheel 81, within a compartment separated from the outside. Figure 3As shown, the steering device 80 includes a gearbox 920, an intermediate plate 10, and a steering column housing 820. The gearbox 920 is mounted on the vehicle, and the steering column housing 820 is fixed to the gearbox 920 via the intermediate plate 10.

[0066] like Figure 1 and Figure 4 As shown, the steering shaft 82 includes an input shaft 82a, an output shaft 82b, and a torsion bar 82c. The input shaft 82a is supported by bearings on... Figure 4 The steering column housing 820 is shown. The input shaft 82a is rotatable relative to the steering column housing 820. One end of the input shaft 82a is connected to the steering wheel 81. The other end of the input shaft 82a is connected to a torsion bar 82c. The torsion bar 82c engages with a hole located at the center of the input shaft 82a and is fixed to the input shaft 82a by a pin.

[0067] like Figure 4 As shown, the output shaft 82b is supported on the intermediate plate 10 by means of bearing 71 and on the gearbox 920 by means of bearing 72. For example, bearing 71 is pressed into the intermediate plate 10 and bearing 72 is pressed into the gearbox 920. The output shaft 82b is rotatable relative to the intermediate plate 10 and the gearbox 920. One end of the output shaft 82b is connected to a torsion bar 82c. The other end of the output shaft 82b is connected to a universal joint 84. The torsion bar 82c is fixed to the output shaft 82b by pressing it into a hole provided in the center of the output shaft 82b.

[0068] Furthermore, the front end of the input shaft 82a is located inside the output shaft 82b. A protrusion on one of the outer circumferential surface of the input shaft 82a and the inner circumferential surface of the output shaft 82b engages with a recess on the other. Thus, even when the torsion bar 82c no longer functions as a connecting member, torque can still be transmitted between the input shaft 82a and the output shaft 82b.

[0069] like Figure 1 As shown, intermediate shaft 85 connects universal joint 84 and universal joint 86. One end of intermediate shaft 85 is connected to universal joint 84, and the other end is connected to universal joint 86. One end of pinion shaft 87 is connected to universal joint 86, and the other end of pinion shaft 87 is connected to steering gear 88. Universal joint 84 and universal joint 86 are, for example, universal joints. Rotation of steering shaft 82 is transmitted to pinion shaft 87 via intermediate shaft 85. That is, intermediate shaft 85 rotates in conjunction with steering shaft 82.

[0070] like Figure 1As shown, the steering gear 88 includes a pinion 88a and a rack 88b. The pinion 88a is connected to a pinion shaft 87. The rack 88b meshes with the pinion 88a. The steering gear 88 uses the rack 88b to convert the rotational motion transmitted to the pinion 88a into straight-line motion. The rack 88b is connected to a tie rod 89. The angle of the wheels changes by moving the rack 88b.

[0071] like Figure 1 As shown, the steering force assist mechanism 83 includes a reduction gear 92 and an electric motor 93. The reduction gear 92 is, for example, a worm gear reduction mechanism, such as... Figure 3 and Figure 4 As shown, the device includes a gearbox 920, a worm gear 921, and a worm 922. The torque generated by the electric motor 93 is transmitted to the worm gear 921 via the worm 922, causing the worm gear 921 to rotate. The worm gear 922 and worm wheel 921 increase the torque generated by the electric motor 93. The worm gear 921 is fixed to the output shaft 82b. For example, the worm gear 921 is pressed into the output shaft 82b. Therefore, the reduction gear 92 applies an auxiliary steering torque to the output shaft 82b. The steering device 80 is a column-assisted electric power steering system.

[0072] like Figure 1 As shown, the steering system 80 includes an ECU (Electronic Control Unit) 90, a torque sensor 1, and a vehicle speed sensor 95. An electric motor 93, torque sensor 1, and vehicle speed sensor 95 are electrically connected to the ECU 90. The torque sensor 1 outputs the steering torque transmitted to the input shaft 82a to the ECU 90 via CAN (Controller Area Network) communication. The vehicle speed sensor 95 detects the vehicle speed of the vehicle body equipped with the steering system 80. The vehicle speed sensor 95 is located on the vehicle body and outputs the vehicle speed to the ECU 90 via CAN communication.

[0073] The ECU 90 controls the operation of the electric motor 93. The ECU 90 receives signals from the torque sensor 1 and the vehicle speed sensor 95, respectively. With the ignition switch 98 on, power is supplied to the ECU 90 from the power supply unit 99 (e.g., the vehicle's battery). The ECU 90 calculates an auxiliary steering command value based on the steering torque and vehicle speed. The ECU 90 adjusts the power supplied to the electric motor 93 based on the auxiliary steering command value. The ECU 90 acquires information about the induced voltage of the electric motor 93 or information output from a processor installed in the electric motor 93. By controlling the electric motor 93, the ECU 90 reduces the force required to operate the steering wheel 81.

[0074] Figure 5 yes Figure 4 A magnified view of a specific part. Figure 6Therefore with Figure 4 Cross-sectional views obtained by cutting the steering device of this embodiment with different planes. Figure 7 yes Figure 6 A magnified view of a specific part. Figure 8 This is a cross-sectional view of the periphery of the magnet assembly in this embodiment. Figure 9 yes Figure 8 A magnified view of a specific part. Figure 10 This is an exploded perspective view showing the magnet assembly and yoke of this embodiment. Figure 11 This is an exploded perspective view of the magnet assembly of this embodiment.

[0075] like Figure 4 As shown, the torque sensor 1 is disposed between the steering column housing 820 and the gearbox 920. More specifically, the torque sensor 1 is located in the space sandwiched between the steering column housing 820 and the intermediate plate 10. Figures 4-7 As shown, the torque sensor 1 includes a magnet assembly 20, a sleeve 31 (second sleeve), a retaining part 32, a magnetic yoke 35, a sensor housing 40, a magnetic collecting component 46, a printed circuit board 43, a Hall IC 47, a first cover 48, and a second cover 49. Figure 8 As shown, the magnet assembly 20 includes a sleeve 21 (first sleeve), an intermediate member 26, and a magnet 25.

[0076] Sleeve 21 is a non-magnetic material and is metallic. A specific example of a non-magnetic metal is austenitic stainless steel (SUS304). Figure 5 As shown, sleeve 21 is a cylindrical component and is mounted on input shaft 82a. Sleeve 21 is formed, for example, by deep drawing. Sleeve 21 includes a rotating member connecting portion 211, an intermediate member connecting portion 215, and an enlarged portion 213. In the following description, the direction parallel to the central axis Z of sleeve 21 is referred to as axial. The direction parallel to a straight line orthogonal to and passing through the central axis Z is referred to as radial. The direction along the circumference centered on the central axis Z is referred to as circumferential. The central axis Z is a straight line that is the same as the rotation axis of input shaft 82a.

[0077] like Figure 8As shown, the rotating member connecting portion 211 is a cylindrical member pressed into the outer peripheral surface of the input shaft 82a. The rear end face of the rotating member connecting portion 211 faces the end face 823a of the raised portion 822a of the input shaft 82a. An annular groove 821a is provided in the portion of the input shaft 82a corresponding to the rear end face of the rotating member connecting portion 211. The intermediate member connecting portion 215 is a cylindrical member. The outer diameter of the intermediate member connecting portion 215 is larger than the outer diameter of the rotating member connecting portion 211. The intermediate member connecting portion 215 is located at a position offset axially relative to the rotating member connecting portion 211. The intermediate member connecting portion 215 is located in front of the rotating member connecting portion 211. The enlarged portion 213 connects the rotating member connecting portion 211 and the intermediate member connecting portion 215. The outer diameter of the enlarged portion 213 increases from the rotating member connecting portion 211 toward the intermediate member connecting portion 215.

[0078] By connecting the rotating member connecting portion 211 and the intermediate member connecting portion 215 using the enlarged portion 213, the rotating member connecting portion 211 and the intermediate member connecting portion 215 can be positioned axially and radially separated. By configuring the sleeve 21 in this way, the stress generated in the rotating member connecting portion 211 during the pressing of the sleeve 21 into the input shaft 82a is absorbed by the deformation of the enlarged portion 213, thus suppressing the transmission of stress generated during the pressing of the sleeve 21 into the intermediate member connecting portion 215.

[0079] A magnet 25 is disposed in the intermediate member connection portion 215 via the intermediate member 26, thereby suppressing the transmission of stress generated during the pressing process to the magnet 25 via the intermediate member connection portion 215 and the intermediate member 26. By suppressing the stress acting on the magnet 25, the degradation of sensor output characteristics that accompanies the demagnetization of the magnet 25 can be suppressed.

[0080] like Figure 8 As shown, the intermediate member connecting portion 215 includes a plurality of recesses 216, a plurality of protrusions 217, and a sleeve end 219. Recesses 216 are provided on the outer peripheral surface of the intermediate member connecting portion 215. Protrusions 217 are provided on the inner peripheral surface of the intermediate member connecting portion 215. Protrusions 217 are provided on the back side of the recesses 216. The recesses 216 and protrusions 217 are formed in one step, for example, by stamping. That is, the recesses 216 and protrusions 217 are formed by plastically deforming the outer peripheral surface of the intermediate member connecting portion 215 radially inward. The protrusions 217 are positioned radially outward from the inner peripheral surface of the rotating member connecting portion 211. That is, the inner diameter I217 of the protrusion 217 is larger than the inner diameter I211 of the rotating member connecting portion 211. The number of recesses 216 and the number of protrusions 217 are both even numbers. Figure 11As shown, an even number of recesses 216 and an even number of protrusions 217 are arranged at equal intervals along the circumference. Therefore, relative to one set of recesses 216 and protrusions 217, there is another set of recesses 216 and protrusions 217 on the opposite side across the central axis Z. The sleeve end 219 is the end of the intermediate member connecting portion 215 on the side opposite to the side where the rotating member connecting portion 211 is located (the front side). The sleeve end 219 extends radially outward.

[0081] like Figure 8 As shown, the intermediate member 26 is disposed on the outer peripheral surface of the intermediate member connecting portion 215. The intermediate member 26 is formed in a ring shape. The intermediate member 26 is a resin. Specific examples of resins include polyphenylene sulfide (PPS) and polyamide 12 (PA12).

[0082] The intermediate member 26 includes a thin-walled portion 261, a plurality of thick-walled portions 263, and an intermediate member end 269. The wall thickness of the thick-walled portion 263 is greater than the wall thickness of the thin-walled portion 261. Wall thickness refers to radial thickness and will be used in the same sense in the following description. In this embodiment, as... Figure 11 As shown, the thin-walled portion 261 is formed in a ring shape, and an even number of thick-walled portions 263 are arranged at equal intervals along the circumference. Figure 8 As shown, in a cross-section including the central axis Z, the thick-walled portion 263 is axially located between a portion of the thin-walled portion 261 and another portion of the thin-walled portion 261. The thick-walled portion 263 is sandwiched between the thin-walled portions 261 from both sides in the axial direction. In other words, in a cross-section including the central axis Z, the wall thickness of the intermediate member 26 is not constant but varies depending on its axial position. The inner peripheral surfaces of the thin-walled portion 261 and the thick-walled portion 263 are in contact with the outer peripheral surface of the intermediate member connecting portion 215. The radially inner end of the thick-walled portion 263 is located in the recess 216 of the intermediate member connecting portion 215.

[0083] The intermediate member end 269 is the end of the intermediate member 26 on the side opposite to the side where the rotating member connection portion 211 is located (the front side). When viewed axially, the intermediate member end 269 partially overlaps with the sleeve end 219. The outer diameter E219 of the sleeve end 219 is larger than the inner diameter I269 of the intermediate member end 269, and smaller than the outer diameter E269 of the intermediate member end 269. For example... Figure 9 As shown, the intermediate member end 269 is arranged axially with a gap C relative to the sleeve end 219. Furthermore, in Figure 9 The gap C is depicted in an exaggerated manner, and the size of the gap C in the illustration may differ from its actual size.

[0084] like Figure 8As shown, magnet 25 is disposed on the outer peripheral surface of intermediate member 26. Magnet 25 is formed in a ring shape. In the ring-shaped magnet 25, S poles and N poles are arranged alternately in the circumferential direction. Magnet 25 is mounted on sleeve 21 by means of intermediate member 26. Therefore, magnet 25 rotates together with input shaft 82a and sleeve 21. Magnet 25 faces yoke 35 with a radial gap. The radial gap L1 between magnet 25 and yoke 35 is smaller than the wall thickness difference L2 between thin-walled portion 261 and thick-walled portion 263. Wall thickness difference L2 can also be referred to as a step between thin-walled portion 261 and thick-walled portion 263.

[0085] Magnet 25 contains magnetic powder, which is a hard magnetic material, and resin. Magnet 25 is formed by curing the material obtained by mixing the magnetic powder and resin. Magnet 25 is referred to as a bonded magnet. Specific examples of hard magnetic materials include ferrite or neodymium. Specific examples of resins include polyphenylene sulfide (PPS) and polyamide 12 (PA12). In this embodiment, the coefficient of linear expansion of the intermediate member 26 is smaller than the coefficient of linear expansion of the resin of the magnet. Alternatively, the resin used for magnet 25 may be the same as the resin used for intermediate member 26.

[0086] like Figure 8 As shown, the magnet 25 includes a mounting portion 251 and a tapered portion 253. The mounting portion 251 is the part that contacts the intermediate member 26. The wall thickness of the mounting portion 251 is constant. The tapered portion 253 is disposed behind the mounting portion 251. The tapered portion 253 faces the rotating member connection portion 211 in the radial direction. The wall thickness of the tapered portion 253 decreases towards one end (rear) in the axial direction. The wall thickness of the tapered portion 253 decreases as it moves away from the mounting portion 251. More specifically, the outer diameter of the tapered portion 253 is constant, and only the inner diameter of the tapered portion 253 increases as it moves away from the mounting portion 251. For example, the axial length of the tapered portion 253 is more than 1 / 4 and less than 1 / 2 of the axial length of the magnet 25 as a whole. When viewed from the axial direction, the magnet 25 does not overlap with the sleeve end 219. The outer diameter E219 of the sleeve end 219 is smaller than the minimum inner diameter I25 of the magnet 25.

[0087] Sleeve 31 is a non-magnetic material and is metallic. A specific example of a non-magnetic metal is austenitic stainless steel (SUS304). Figure 5 As shown, sleeve 31 is a cylindrical component and is mounted on output shaft 82b. Specifically, sleeve 31 is pressed into the outer circumferential surface of output shaft 82b. The front end face of sleeve 31 does not contact output shaft 82b. That is, there is an axial gap between the front end face of sleeve 31 and output shaft 82b. The axial position of the rear end face of sleeve 31 is the same as the axial position of the rear end face of output shaft 82b. The position of sleeve 31 is determined by aligning the rear end face of sleeve 31 with the rear end face of output shaft 82b.

[0088] The retaining part 32 is a non-magnetic material. For example, the retaining part 32 is resin. Specific examples of resin include polybutylene terephthalate (PBT) or polyoxymethylene (POM). The retaining part 32 is a cylindrical component and is mounted to the output shaft 82b by means of a sleeve 31. Figure 5 As shown, the retaining part 32 includes a small-diameter part 321, a large-diameter part 322, and a protrusion 327. (As...) Figure 5 As shown, the retaining part 32 is integrally formed with the sleeve 31 by injection molding. The small-diameter part 321 is a cylindrical component and contacts the outer peripheral surface of the sleeve 31. The large-diameter part 322 is a cylindrical component. The outer diameter of the large-diameter part 322 is larger than the outer diameter of the small-diameter part 321. The large-diameter part 322 is located behind the small-diameter part 321. The front end of the large-diameter part 322 is connected to the rear end of the small-diameter part 321. The protrusion 327 protrudes rearward from the rear end face of the small-diameter part 321 and faces the magnet 25. There is a gap between the protrusion 327 and the magnet 25.

[0089] like Figure 10 As shown, the magnetic yoke 35 includes a first magnetic yoke 351 and a second magnetic yoke 352. The first magnetic yoke 351 and the second magnetic yoke 352 are soft magnetic materials. A nickel-iron alloy is cited as a specific example of a soft magnetic material. The first magnetic yoke 351 and the second magnetic yoke 352 are fixed to the retaining portion 32. The first magnetic yoke 351 and the second magnetic yoke 352 rotate together with the output shaft 82b, the sleeve 31, and the retaining portion 32. The first magnetic yoke 351 includes a first annular portion 351a and a plurality of first teeth 351b. The first annular portion 351a is a plate orthogonal to the axial direction. The first teeth 351b protrude forward from the first annular portion 351a. The plurality of first teeth 351b are arranged at equal intervals circumferentially. The second magnetic yoke 352 includes a second annular portion 352a and a plurality of second teeth 352b. The second annular portion 352a is a plate parallel to the first annular portion 351a and located in front of the first annular portion 351a. The second tooth portion 352b protrudes rearward from the second annular portion 352a. A plurality of second teeth portions 352b are arranged at equal intervals circumferentially. One second tooth portion 352b is located between two first teeth portions 351b. That is, the first teeth portions 351b and second teeth portions 352b are arranged alternately circumferentially. The first teeth portions 351b and second teeth portions 352b face the magnet 25.

[0090] The sensor housing 40 is a non-magnetic material. For example, the sensor housing 40 is made of resin. Specific examples of resin include polybutylene terephthalate (PBT) or polyamide 66. Figure 5 As shown, a bushing 403 is disposed in the hole 401 of the sensor housing 40. For example, the bushing 403 is made of aluminum alloy and is integrally formed with the sensor housing 40. The sensor housing 40 is fixed to the intermediate plate 10 by bolts passing through the bushing 403.

[0091] like Figure 7 As shown, the magnetic collecting component 46 includes a first magnetic collecting component 461 and a second magnetic collecting component 462. The first magnetic collecting component 461 and the second magnetic collecting component 462 are soft magnetic materials, such as a nickel-iron alloy. The first magnetic collecting component 461 and the second magnetic collecting component 462 are fixed to the sensor housing 40. Figure 7 As shown, the first magnetic unit 461 faces the first annular portion 351a. A gap exists between the first magnetic unit 461 and the first annular portion 351a. The first magnetic unit 461 is magnetized in accordance with the magnetization of the first magnetic yoke 351. The second magnetic unit 462 faces the second annular portion 352a. A gap exists between the second magnetic unit 462 and the second annular portion 352a. The second magnetic unit 462 is magnetized in accordance with the magnetization of the second magnetic yoke 352.

[0092] The torque sensor 1 is designed based on a sufficient safety margin, but vibrations or impacts applied to it may cause the magnet 25 and sleeve 21 to shift axially relative to the input shaft 82a. Alternatively, there is a possibility that the yoke 35, sleeve 31, and retaining portion 32 may shift axially relative to the output shaft 82b. In the torque sensor 1 of this embodiment, even if the sleeve 21 moves relative to the input shaft 82a, the shift of the magnet 25 is easily kept below an acceptable value by bringing the magnet 25 into contact with the retaining portion 32. Furthermore, even if the sleeve 31 and retaining portion 32 move relative to the output shaft 82b, the shift of the yoke 35 is easily kept below an acceptable value by bringing the retaining portion 32 into contact with the magnet 25. Thus, the torque sensor 1 is robust. Therefore, the torque sensor 1 can suppress the reduction in detection accuracy.

[0093] A printed circuit board 43 is fixed to the sensor housing 40. A Hall IC 47 is mounted on the printed circuit board 43. The Hall IC 47 is positioned between a first magnetic unit 461 and a second magnetic unit 462. Gaps exist between the Hall IC 47 and the first magnetic unit 461, and between the Hall IC 47 and the second magnetic unit 462. Changes in the magnetic flux density between the Hall IC 47 and the first and second magnetic units 461 and 462 correspondingly cause changes in the output signal. The Hall IC 47 outputs a signal to the ECU 90.

[0094] When the steering wheel 81 is operated, torque is transmitted to the input shaft 82a. Since the output shaft 82b is connected to the input shaft 82a via a torsion bar 82c, the input shaft 82a rotates relative to the output shaft 82b. Therefore, the magnet 25 rotates relative to the first tooth 351b and the second tooth 352b. This causes a change in the magnetization intensity of the first yoke 351 and the second yoke 352. Consequently, the magnetic flux density between the first magnetic collector 461 and the second magnetic collector 462 changes. The Hall IC 47 detects this change in magnetic flux density. The ECU 90 uses the steering torque calculated based on the output signal of the Hall IC 47 to control the electric motor 93.

[0095] The first cover 48 is a non-magnetic material. For example, the first cover 48 is a resin. Specific examples of resins include polybutylene terephthalate (PBT) or polyamide 66. Figure 6 As shown, the first cover 48 is mounted at the rear end of the sensor housing 40. The first cover 48 covers the printed circuit board 43.

[0096] The second cover 49 is a non-magnetic material. For example, the second cover 49 is a resin. Specific examples of resins include polybutylene terephthalate (PBT) or polyamide 66. Figure 6 As shown, the second cover 49 is mounted on the front end of the sensor housing 40. Figure 7 As shown, the second cover 49 includes an annular main body 491 and a plurality of claw portions 492. The plurality of claw portions 492 are arranged at equal intervals along the circumference. The claw portions 492 protrude forward from the main body 491. The plurality of claw portions 492 are inserted into the intermediate plate 10 by light pressing, and the plurality of claw portions 492 are brought into contact with the inner circumferential surface of the intermediate plate 10. As a result, the center of the sensor housing 40 is easily aligned with the center of the intermediate plate 10 when viewed from the axial direction.

[0097] Figures 12-18 This is a schematic diagram illustrating the manufacturing method of the magnet assembly according to this embodiment. The manufacturing method of the magnet assembly 20 according to this embodiment includes a sleeve processing step, a first mold configuration step, an intermediate component forming step, a second mold configuration step, and a magnet forming step.

[0098] In the sleeve machining process, such as Figure 12 As shown, the outer peripheral surface of the intermediate member connecting portion 215 is plastically deformed in the radial direction. For example, the outer peripheral surface of the intermediate member connecting portion 215 is plastically deformed in the radial direction by stamping, thereby forming a concave portion 216 and a convex portion 217.

[0099] The first mold configuration step is performed after the sleeve machining process. In the first mold configuration step, as follows... Figure 13As shown, a first mold 51 is disposed on the outer side of the intermediate component connecting portion 215. The first mold 51 is a hollow mold formed of metal. The first mold 51 includes an inlet flow path for introducing resin and a outlet flow path for discharging resin. The first mold 51 can be divided into two parts along a plane including the central axis Z. Figure 13 As indicated by the arrow, the first mold 51, which is divided, is installed on the middle component connecting part 215 from both sides.

[0100] The intermediate component forming step is performed after the first mold configuration step. In the intermediate component forming step, such as... Figure 14 As shown, resin is filled into the first mold 51. Injection molding is used in the intermediate component forming step. That is, the nozzle of the cylinder containing molten resin is positioned in the inlet flow path of the first mold 51. The molten resin is extruded from the cylinder and fed into the first mold 51. Excess molten resin is discharged from the outlet flow path of the first mold 51. After the molten resin in the first mold 51 cools, as... Figure 15 The first mold 51 is removed as shown. This forms an intermediate member 26, which includes a thin-walled portion 261 and a thick-walled portion 263.

[0101] The second mold configuration step is performed after the intermediate component formation step. In the second mold configuration step, as follows... Figure 16 As shown, a second mold 52 is disposed on the outer side of the intermediate member 26. The second mold 52 is a hollow mold formed of metal. The second mold 52 includes an inlet flow path for introducing resin and a outlet flow path for discharging resin. The second mold 52 can be divided into two parts along a plane orthogonal to the central axis Z. Figure 16 As indicated by the arrow, the divided second mold 52 is installed on the middle component 26 from both sides.

[0102] The magnet forming step is performed after the second mold configuration step. In the magnet forming step, as follows... Figure 17 As shown, resin is filled into the second mold 52. Injection molding is used in the magnet forming step. That is, the nozzle of the cylinder containing molten resin is positioned in the inlet flow path of the second mold 52. The molten resin is extruded from the cylinder and fed into the second mold 52. Excess molten resin is discharged from the outlet flow path of the second mold 52. After the molten resin in the second mold 52 cools, as... Figure 18 The second mold 52 is removed as shown. This forms a magnet 25 including a mounting portion 251 and a tapered portion 253.

[0103] Furthermore, sleeve 21 is not necessarily mounted on input shaft 82a. For example, sleeve 21 and magnet 25 can be mounted on output shaft 82b, while sleeve 31 and yoke 35 can be mounted on input shaft 82a. When sleeve 21 is mounted on output shaft 82b, sleeve 21 is pressed into the outer circumferential surface of output shaft 82b.

[0104] The intermediate member connecting portion 215 of the sleeve 21 does not necessarily include both the recess 216 and the protrusion 217. The intermediate member connecting portion 215 only needs to include a portion for the thick-walled portion 263 to hook onto. For example, the intermediate member connecting portion 215 may have a through hole into which the thick-walled portion 263 enters. The outer diameter of the intermediate member connecting portion 215 is not necessarily larger than the outer diameter of the rotating member connecting portion 211. The outer diameter of the intermediate member connecting portion 215 may be smaller than or the same as the outer diameter of the rotating member connecting portion 211.

[0105] As described above, the torque sensor 1 of this embodiment includes a sleeve 21, an intermediate member 26, a magnet 25, and a yoke 35. The sleeve 21 is an annular member mounted on the first rotating member (input shaft 82a). The intermediate member 26 is an annular member disposed on the outer peripheral surface of the sleeve 21. The magnet 25 is an annular member disposed on the outer peripheral surface of the intermediate member 26. The yoke 35 is mounted on a second rotating member (output shaft 82b) that rotates relative to the first rotating member, and faces the magnet 25 radially upward in a direction orthogonal to the central axis Z of the sleeve 21. The sleeve 21 includes a rotating member connecting portion 211 and an intermediate member connecting portion 215. The rotating member connecting portion 211 is cylindrical and contacts the first rotating member. The intermediate member connecting portion 215 is cylindrical and is located offset from the rotating member connecting portion 211 in an axial direction parallel to the central axis Z. The intermediate member 26 includes a thin-walled portion 261 and a thick-walled portion 263 having a wall thickness greater than that of the thin-walled portion 261. The inner peripheral surfaces of the thin-walled portion 261 and the thick-walled portion 263 are in contact with the intermediate member connecting portion 215.

[0106] By contacting the rotating member connecting portion 211 with the first rotating member (input shaft 82a), deformation of the intermediate member connecting portion 215 holding the magnet 25 can be suppressed when the sleeve 21 is pressed into the first rotating member. Therefore, the distance between the magnet 25 and the yoke 35 (first tooth 351b and second tooth 352b) is less likely to deviate from the design value. Thus, the torque sensor 1 can suppress the reduction in detection accuracy. Furthermore, in the aforementioned Patent Document 1, the magnet is mounted to the sleeve using an adhesive, requiring the magnet to be aligned with the sleeve before mounting during sensor production, resulting in a complex manufacturing process. In contrast, in the torque sensor 1 of this embodiment, the intermediate member 26 includes a thin-walled portion 261 and a thick-walled portion 263. Thus, the thick-walled portion 263 hooks onto the outer peripheral surface of the sleeve 21. Relative movement of the intermediate member 26 and the sleeve 21 in the axial and circumferential directions is suppressed. Furthermore, when the torque sensor 1 of this embodiment is manufactured according to the above-described principles, after the intermediate member 26 is formed on the outer periphery of the sleeve 21, the magnet 25 is formed on the outer periphery of the intermediate member 26. Therefore, it is not necessary to position the magnet 25 relative to the sleeve 21, thus simplifying the production process.

[0107] In the torque sensor 1 of this embodiment, the outer diameter of the intermediate member connecting part 215 is larger than the outer diameter of the rotating member connecting part 211.

[0108] Therefore, the stress generated in the rotating member connection 211 during the pressing of the sleeve 21 into the input shaft 82a is absorbed by the deformation of the enlarged portion 213 located between the rotating member connection 211 and the intermediate member connection 215. Thus, the transmission of stress generated during the pressing of the sleeve 21 to the intermediate member connection 215 can be suppressed.

[0109] In the torque sensor 1 of this embodiment, the outer diameter of the intermediate member connecting part 215 may be smaller than the outer diameter of the rotating member connecting part 211.

[0110] Therefore, compared to the case where the outer diameter of the intermediate member connecting portion 215 is larger than the outer diameter of the rotating member connecting portion 211, the magnet 25 can be positioned further inward in the radial direction. Thus, miniaturization of the torque sensor 1 is possible.

[0111] Alternatively, the outer diameter of the intermediate member connecting part 215 may be the same as the outer diameter of the rotating member connecting part 211.

[0112] Therefore, compared to the case where the outer diameter of the intermediate member connecting portion 215 is larger than the outer diameter of the rotating member connecting portion 211, the magnet 25 can be positioned further inward in the radial direction. This allows for miniaturization of the torque sensor 1. Furthermore, the shape of the sleeve 21 becomes simpler, thus simplifying the manufacturing process of the sleeve 21.

[0113] In the torque sensor 1 of this embodiment, the magnet 25 includes a tapered portion 253 with a reduced wall thickness at one end facing the axial direction. The tapered portion 253 faces the rotating member connection portion 211 in the radial direction.

[0114] To reduce the stress acting on the magnet 25 when the rotating member connecting portion 211 is pressed into the first rotating member (input shaft 82a), a radial gap is provided between the magnet 25 and the small-diameter portion. To form this gap, a mold (second mold 52) needs to be inserted into the gap during the formation of the magnet 25. In the torque sensor 1 of this embodiment, by including a tapered portion 253 in the magnet 25, the mold used can be easily removed during the formation of the magnet 25.

[0115] In the torque sensor 1 of this embodiment, the intermediate member 26 includes an even number of thick-walled portions 263. The even number of thick-walled portions 263 are arranged at equal intervals in the circumferential direction.

[0116] The recesses in the sleeve 21 corresponding to the thick-walled portion 263 are formed, for example, by stamping. An even number of recesses are arranged at equal intervals in the circumferential direction, thus facilitating the stamping of the sleeve 21. Furthermore, forming the recesses by stamping is preferred when the sleeve 21 is a thin-walled cylindrical shape. By making the sleeve shape thinner, the torque sensor 1 can be made lighter.

[0117] In the torque sensor 1 of this embodiment, in a cross section including the central axis Z, the thick-walled portion 263 is located axially between a portion of the thin-walled portion 261 and another portion of the thin-walled portion 261.

[0118] Assuming that the thick-walled portion 263 is disposed at the axial end of the intermediate member 26, in order to prevent the intermediate member 26 from moving relative to the sleeve 21, the thick-walled portion 263 needs to be provided at both ends of the intermediate member 26. That is, the thick-walled portion 263 needs to be arranged in two rows. In contrast, in the torque sensor 1 of this embodiment, it is possible to prevent the intermediate member 26 from moving relative to the sleeve 21 as long as there is at least one thick-walled portion 263. The torque sensor 1 of this embodiment can reduce the number of thick-walled portions 263 required.

[0119] In the torque sensor 1 of this embodiment, the intermediate member connecting portion 215 includes a recess 216 provided on the outer peripheral surface and a protrusion 217 provided on the back side of the recess 216.

[0120] Therefore, the recess 216 and the protrusion 217 can be easily formed by stamping. The torque sensor 1 of this embodiment can easily perform the process of forming the portion for hooking the thick-walled portion 263 on the sleeve 21.

[0121] In the torque sensor 1 of this embodiment, the protrusion 217 is disposed at a position radially outward of the inner circumferential surface of the rotating member connecting portion 211.

[0122] Therefore, when the sleeve 21 is pressed into the first rotating member (input shaft 82a), the protrusion 217 does not contact the first rotating member. Thus, no force is applied directly from the first rotating member to the intermediate member connection 215. The torque sensor 1 of this embodiment can reduce the stress generated in the intermediate member 26 and the magnet 25.

[0123] In the torque sensor 1 of this embodiment, the radial distance L1 between the magnet 25 and the yoke 35 is smaller than the wall thickness difference L2 between the thin-walled portion 261 and the thick-walled portion 263.

[0124] Therefore, it is assumed that even if the magnet 25 malfunctions and moves towards the yoke 35, the thick-walled portion 263 will remain hooked onto the sleeve 21. Thus, the magnet 25 will not detach from the sleeve 21. The torque sensor 1 of this embodiment reduces the possibility of it becoming unoutputtable.

[0125] In the torque sensor 1 of this embodiment, the intermediate component 26 is resin. The magnet 25 contains magnetic powder and resin. The coefficient of linear expansion of the intermediate component 26 is smaller than the coefficient of linear expansion of the resin in the magnet 25.

[0126] Therefore, the torque sensor 1 of this embodiment can reduce the stress generated in the intermediate member 26 and the magnet 25 even when the intermediate member 26 and the magnet 25 are exposed to an environment with temperature changes.

[0127] In the torque sensor 1 of this embodiment, the intermediate component 26 is resin. The magnet 25 contains magnetic powder and resin. The resin of the intermediate component 26 and the resin of the magnet 25 are the same material.

[0128] Therefore, the torque sensor 1 of this embodiment can reduce the stress generated in the intermediate member 26 and the magnet 25 even when the intermediate member 26 and the magnet 25 are exposed to an environment with temperature changes.

[0129] The manufacturing method of the magnet assembly 20 in this embodiment includes a first mold arrangement step, an intermediate member formation step, a second mold arrangement step, and a magnet formation step. The first mold arrangement step is a process of arranging the first mold 51 on the outside of the intermediate member connecting portion 215. The intermediate member formation step is a process of forming an intermediate member 26, including a thin-walled portion 261 and a thick-walled portion 263 having a wall thickness greater than that of the thin-walled portion 261, by filling the first mold 51 with resin. The second mold arrangement step is a process of arranging the second mold 52 on the outside of the intermediate member 26. The magnet formation step is a process of forming a magnet 25 by filling the second mold 52 with resin containing magnet powder.

[0130] Therefore, the resin-containing intermediate member 26 and the magnet 25 can be firmly attached to each other. Thus, relative movement between the intermediate member 26 and the magnet 25 in the axial and circumferential directions is suppressed. Furthermore, the intermediate member 26 includes a thin-walled portion 261 and a thick-walled portion 263. Thus, the thick-walled portion 263 hooks onto the outer circumferential surface of the sleeve 21. Relative movement between the intermediate member 26 and the sleeve 21 in the axial and circumferential directions is suppressed. Therefore, the possibility of positional displacement of the magnet 25 can be reduced. Therefore, the manufacturing method of the magnet assembly 20 of this embodiment can further suppress the reduction in detection accuracy.

[0131] The manufacturing method of the magnet assembly 20 in this embodiment includes a sleeve processing step that plastically deforms the outer peripheral surface of the intermediate member connecting portion 215 in a radial direction orthogonal to the central axis Z before the first mold configuration step.

[0132] Therefore, the manufacturing method of the magnet assembly 20 of this embodiment can, for example, easily form the portion for hooking the thick-walled portion 263 on the sleeve 21 by stamping.

[0133] In the manufacturing method of the magnet assembly 20 of this embodiment, injection molding is used in the intermediate component forming step and the magnet forming step.

[0134] Therefore, the manufacturing method of the magnet assembly 20 of this embodiment can more easily form the intermediate component 26 and the magnet 25.

[0135] Furthermore, the torque sensor 1 of this embodiment includes a sleeve 21, an intermediate member 26, a magnet 25, and a yoke 35. The sleeve 21 is an annular member mounted on the first rotating member (input shaft 82a). The intermediate member 26 is an annular member disposed on the outer circumferential surface of the sleeve 21. The magnet 25 is an annular member disposed on the outer circumferential surface of the intermediate member 26. The yoke 35 is mounted on a second rotating member (output shaft 82b) that rotates relative to the first rotating member, and faces the magnet 25 radially upward in a direction orthogonal to the central axis Z of the sleeve 21. The sleeve 21 includes a rotating member connecting portion 211 and an intermediate member connecting portion 215. The rotating member connecting portion 211 is cylindrical and contacts the first rotating member. The intermediate member connecting portion 215 is cylindrical and located at a position offset axially from the rotating member connecting portion 211 in a direction parallel to the central axis Z. The outer diameter E219 of the sleeve end 219 of the intermediate member connecting part 215, which is opposite to the side where the rotating member connecting part 211 is located, is smaller than the minimum inner diameter I25 of the magnet 25.

[0136] By contacting the rotating member connecting portion 211 with the first rotating member (input shaft 82a), deformation of the intermediate member connecting portion 215 holding the magnet 25 can be suppressed when the sleeve 21 is pressed into the first rotating member. Therefore, the distance between the magnet 25 and the yoke 35 (first tooth 351b and second tooth 352b) is less likely to deviate from the design value. Thus, the torque sensor 1 can suppress the reduction in detection accuracy. Furthermore, the sleeve supporting the magnet in Patent Document 1 preferably has a small diameter portion and a large diameter portion and is small in the radial direction. However, if the step between the small diameter portion and the large diameter portion is reduced, it becomes impossible to press the step between the small diameter portion and the large diameter portion when pressing the sleeve into the steering shaft. Although the top end of the large diameter portion can be pressed instead of the step, stress may sometimes be generated in the magnet when pressing the top end of the large diameter portion. If stress is generated in the magnet, the magnetic properties of the magnet will change, and it is possible to manufacture a magnet that does not meet the factory standards. Therefore, the yield rate in the manufacturing of the steering device will decrease. In contrast, in the torque sensor 1 of this embodiment, the outer diameter E219 of the sleeve end 219 is smaller than the minimum inner diameter I25 of the magnet 25. Therefore, when the sleeve 21 is pressed into the first rotating member, stress is not easily generated in the magnet 25 even when the sleeve end 219 is pressed. Therefore, the torque sensor 1 of this embodiment can suppress the decrease in detection accuracy and can suppress the generation of stress in the magnet 25 when fixed to the rotating member.

[0137] In the torque sensor 1 of this embodiment, the outer diameter E219 of the sleeve end 219 is larger than the inner diameter I269 of the end of the intermediate member 26 on the side opposite to the side where the rotating member connection portion 211 is located, i.e., the intermediate member end 269, and smaller than the outer diameter E269 of the intermediate member end 269.

[0138] Therefore, the sleeve end 219 prevents the intermediate member 26 from moving, thus reducing the possibility of positional displacement of the intermediate member 26. Consequently, the torque sensor 1 of this embodiment can further reduce the possibility of a decrease in detection accuracy.

[0139] In the torque sensor 1 of this embodiment, the intermediate member 26 is arranged with a gap C in the axial direction relative to the sleeve end 219.

[0140] Therefore, when the sleeve 21 is pressed into the first rotating member, deformation of the intermediate member 26 is less likely to occur even when the sleeve end 219 is pressed. As a result, stress is less likely to be generated in the magnet 25 that contacts the intermediate member 26. Therefore, the torque sensor 1 of this embodiment can further suppress the stress generated in the magnet 25 when fixed to the rotating member.

[0141] (First variation)

[0142] Figure 19 This is a cross-sectional view of the periphery of the magnet assembly in the first modified example. Furthermore, the same reference numerals are used for components that are identical to those described in the above embodiments, and repeated descriptions are omitted.

[0143] like Figure 19 As shown, the magnet assembly 20A of the first modified example includes a sleeve 21A and an intermediate member 26A. The sleeve 21A includes an intermediate member connecting portion 215A. The intermediate member connecting portion 215A includes a plurality of protrusions 216A, a plurality of recesses 217A, and a sleeve end 219A. The protrusions 216A are provided on the outer peripheral surface of the intermediate member connecting portion 215A. The recesses 217A are provided on the inner peripheral surface of the intermediate member connecting portion 215A. The recesses 217A are provided on the back side of the protrusions 216A. The protrusions 216A and the recesses 217A are formed in one step, for example, by stamping. That is, the protrusions 216A and the recesses 217A are formed by plastically deforming the outer peripheral surface of the intermediate member connecting portion 215A radially outward. The plurality of protrusions 216A and the plurality of recesses 217A are arranged at equal intervals in the circumferential direction. The sleeve end 219A is the end of the intermediate member connecting portion 215A on the side opposite to the side where the rotating member connecting portion 211 is located (the front side). The sleeve end 219A extends radially outward.

[0144] The intermediate member 26A includes a thick-walled portion 265, a plurality of thin-walled portions 267, and an intermediate member end 269A. The wall thickness of the thin-walled portion 267 is smaller than that of the thick-walled portion 265. The thick-walled portion 265 is formed in a ring shape, and an even number of thin-walled portions 267 are arranged at equal intervals along the circumference. In a cross-section including the central axis Z, the thin-walled portion 267 is located axially between one part of the thick-walled portion 265 and another part of the thick-walled portion 265. The thin-walled portion 267 is sandwiched between the thick-walled portions 265 from both sides along the axial direction. In other words, in a cross-section including the central axis Z, the wall thickness of the intermediate member 26A is not constant but varies depending on its axial position. The inner circumferential surfaces of the thick-walled portion 265 and the thin-walled portion 267 are in contact with the outer circumferential surface of the intermediate member connecting portion 215A. In addition, the radial spacing L1 between the magnet 25 and the yoke 35 is smaller than the wall thickness difference L3 between the thin-walled portion 261 and the thick-walled portion 263.

[0145] The intermediate member end 269A is the end of the intermediate member 26A on the side opposite to the side where the rotating member connecting portion 211 is located (the front side). When viewed axially, the intermediate member end 269A partially overlaps with the sleeve end 219A. The outer diameter E219A of the sleeve end 219A is larger than the inner diameter I269A of the intermediate member end 269A, and smaller than the outer diameter E269A of the intermediate member end 269A. Figure 9 Similarly, the intermediate member end 269A is arranged with a gap in the axial direction relative to the sleeve end 219A, as shown in the relationship between the intermediate member end 269A and the sleeve end 219A.

[0146] As described above, in the first variation, the intermediate member 26 includes an even number of thin-walled portions 267. When viewed from the axial direction, the even number of thin-walled portions 267 are arranged at equal intervals along the circumferential direction centered on the central axis Z.

[0147] The protrusions of the sleeve 21A corresponding to the thin-walled portion 267 are formed, for example, by stamping. An even number of protrusions are arranged at equal intervals in the circumferential direction, thus facilitating the stamping of the sleeve 21. Furthermore, forming the protrusions by stamping is preferred when the sleeve 21A is a thin-walled cylindrical shape. By making the sleeve shape thinner, the torque sensor 1 can be made lighter.

[0148] (Second variation)

[0149] Figure 20 This is a cross-sectional view of the periphery of the magnet assembly in the second modified example. Furthermore, the same reference numerals are used for components that are identical to those described in the above embodiments, and repeated descriptions are omitted.

[0150] like Figure 20As shown, the magnet assembly 20B of the second modification includes a sleeve 21B. The sleeve 21B includes an intermediate member connecting portion 215B. The intermediate member connecting portion 215B includes a sleeve end 219B. The sleeve end 219B is the end of the intermediate member connecting portion 215B on the side opposite to the side where the rotating member connecting portion 211 is located (the front side). The sleeve end 219B extends radially outward.

[0151] Viewed axially, the intermediate member end 269 does not overlap with the sleeve end 219B. The outer diameter E219B of the sleeve end 219B is less than or equal to the inner diameter I269 of the intermediate member end 269. For example, in the second variation, the outer diameter E219B of the sleeve end 219B is equal to the inner diameter I269 of the intermediate member end 269. The sleeve end 219B protrudes axially (forward) relative to the plane passing through the end faces of the intermediate member 26 and the magnet 25.

[0152] As explained above, in the second variation, the outer diameter E219B of the sleeve end 219B is less than the inner diameter I269 of the end of the intermediate member 26 on the side opposite to the side where the rotating member connection 211 is located, i.e., the end of the intermediate member 269.

[0153] Therefore, when the sleeve 21B is pressed into the first rotating member, deformation of the intermediate member 26 is less likely to occur even when the sleeve end 219B is pressed. As a result, stress is less likely to be generated in the magnet 25 that is in contact with the intermediate member 26. Therefore, the magnet assembly 20B of the second modified example can further suppress the stress generated in the magnet 25 when fixed to the rotating member.

[0154] Explanation of reference numerals in the attached figures

[0155] 1. Torque sensor; 10. Intermediate plate; 20, 20A, 20B. Magnet assembly; 21, 21A, 21B. Sleeve; 25. Magnet; 26, 26A. Intermediate component; 31. Sleeve; 32. Retaining part; 35. Magnetic yoke; 40. Sensor housing; 43. Printed circuit board; 46. Magnet collecting component; 47. Hall IC; 71, 72. Bearing; 80. Steering device; 81. Steering wheel; 82. Steering shaft; 82a. Input shaft; 82b. Output shaft; 82c. Torque bar; 83. Steering force assist mechanism; 84. Universal joint; 85. Intermediate shaft; 86. Universal joint; 87. Pinion shaft; 88. Steering gear; 88a. Pinion; 88b. Rack; 89. Tie rod; 90. ECU; 92. Reduction device; 93. Electric motor; 95. Vehicle speed sensor; 98. Ignition switch; 99. Power supply unit; 211. Rotating component connecting part; 213. Enlarged part; 215, 215A, 215B. Intermediate component connecting part; 216. Recess; 216A. Protrusion; 217. Protrusion; 217A. Recess; 219, 219A, 219B. Sleeve end; 251. Mounting part; 253. Tapered part; 261. Thin-walled part; 263. Thick-walled part; 265. Thick-walled part; 267. Thin-walled part; 269, 269A. Intermediate component end; 321. Small diameter part; 322. Large diameter part; 327. Protrusion; 920. Gearbox; 921. Worm gear; 922. Worm; C. Clearance; L1. Spacing; L2, L3. Wall thickness difference; Z. Central axis.

Claims

1. A torque sensor, wherein, The torque sensor includes: An annular sleeve is mounted on the first rotating component; An annular intermediate member, which is cylindrical and disposed on the outer circumferential surface of the sleeve; A ring-shaped magnet is disposed on the outer peripheral surface of the intermediate member; and A magnetic yoke, which is mounted on a second rotating member that rotates relative to the first rotating member, and faces the magnet in a radial direction orthogonal to the central axis of the sleeve. The sleeve includes: A rotating component connecting portion, which is cylindrical and contacts the first rotating component; and The intermediate component connecting portion is cylindrical and is located axially offset from the rotating component connecting portion, parallel to the central axis. The intermediate component includes a thin-walled portion and a thick-walled portion having a wall thickness greater than that of the thin-walled portion in the radial direction. The inner circumferential surfaces of the thin-walled portion and the thick-walled portion are in contact with the connecting portion of the intermediate component. The radially inner end of the thick-walled portion is located in the recess of the intermediate member connecting portion, or the intermediate member connecting portion has a protrusion on its outer peripheral surface, and the protrusion contacts the inner peripheral surface of the thin-walled portion.

2. The torque sensor according to claim 1, wherein, The outer diameter of the intermediate component connection is larger than the outer diameter of the rotating component connection.

3. The torque sensor according to claim 1, wherein, The outer diameter of the intermediate component connection is smaller than the outer diameter of the rotating component connection.

4. The torque sensor according to claim 1, wherein, The outer diameter of the intermediate component connecting part is the same as the outer diameter of the rotating component connecting part.

5. The torque sensor according to any one of claims 1 to 4, wherein, The magnet includes a tapered portion whose wall thickness decreases towards one end facing the axial direction. The tapered portion faces the rotating component connection portion in the radial direction.

6. The torque sensor according to any one of claims 1 to 4, wherein, The intermediate component includes an even number of the thin-walled portions or an even number of the thick-walled portions. When viewed from the axial direction, an even number of the thin-walled portions or an even number of the thick-walled portions are arranged at equal intervals along the circumferential direction centered on the central axis.

7. The torque sensor according to any one of claims 1 to 4, wherein, In a cross-section including the central axis, the thick-walled portion is located axially between a portion of the thin-walled portion and another portion of the thin-walled portion.

8. The torque sensor according to any one of claims 1 to 4, wherein, The intermediate component connecting part includes a recess on the outer peripheral surface and a protrusion on the inner peripheral surface at a position corresponding to the recess.

9. The torque sensor according to claim 8, wherein, The protrusion on the inner circumferential surface of the intermediate component connecting part is positioned radially outward from the inner circumferential surface of the rotating component connecting part.

10. The torque sensor according to any one of claims 1 to 4, wherein, The radial spacing between the magnet and the yoke is smaller than the difference in wall thickness between the thin-walled portion and the thick-walled portion.

11. The torque sensor according to any one of claims 1 to 4, wherein, The intermediate component is resin. The magnet contains magnetic powder and resin. The coefficient of linear expansion of the intermediate component is smaller than that of the resin of the magnet.

12. The torque sensor according to any one of claims 1 to 4, wherein, The intermediate component is resin. The magnet contains magnetic powder and resin. The resin of the intermediate component and the resin of the magnet are the same material.

13. A method for manufacturing a magnet assembly, which is a method for manufacturing a magnet assembly for a torque sensor, wherein, The torque sensor includes: An annular sleeve is used for mounting on the first rotating component; An annular intermediate member, which is cylindrical and disposed on the outer circumferential surface of the sleeve; A ring-shaped magnet is disposed on the outer peripheral surface of the intermediate member; and A magnetic yoke, which is mounted on a second rotating member that rotates relative to the first rotating member, and faces the magnet in a radial direction orthogonal to the central axis of the sleeve. The sleeve includes: A rotating component connecting portion, which is cylindrical and contacts the first rotating component; and The intermediate component connecting portion is cylindrical and located axially offset from the central axis of the sleeve relative to the rotating component connecting portion. The method for manufacturing this magnet assembly includes: The first mold configuration step involves configuring the first mold on the outside of the intermediate component connection portion. An intermediate component forming step, in which an intermediate component is formed by filling the first mold with resin, including a thin-walled portion and a thick-walled portion having a wall thickness greater than that of the thin-walled portion in the radial direction; The second mold configuration step involves configuring the second mold on the outside of the intermediate member. The magnet forming step involves forming the magnet by filling the second mold with resin containing magnet powder. The inner circumferential surfaces of the thin-walled portion and the thick-walled portion are in contact with the connecting portion of the intermediate component. The radially inner end of the thick-walled portion is located in the recess of the intermediate member connecting portion, or the intermediate member connecting portion has a protrusion on its outer peripheral surface, and the protrusion contacts the inner peripheral surface of the thin-walled portion.

14. The method for manufacturing a magnet assembly according to claim 13, wherein, The manufacturing method of the magnet assembly includes a sleeve machining process that plastically deforms the outer peripheral surface of the intermediate component connecting part in a radial direction orthogonal to the central axis before the first mold configuration step.

15. The method of manufacturing a magnet assembly according to claim 13 or 14, wherein, Injection molding is used in the intermediate component formation step and the magnet formation step.

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