Detection device, program, and control method

Abstract

This detection device is used in a mechanical device (10) that comprises rotating bodies (11, 14), and a hub bearing (40) that rotatably supports the rotating bodies with respect to a base part (15). The hub bearing includes a first cylindrical part (51) and comprises: a first bearing member (50); a second bearing member (60) having a second cylindrical part (61) and a flange part (62); a rolling element (41) provided between the first cylindrical part and the second cylindrical part; a sensor substrate (100); and a target member (80, 180). Protrusions (83, 183) and recesses (84, 184) are alternately provided in a portion of the target member, the portion facing the sensor substrate. The sensor substrate outputs a voltage signal corresponding to the relative displacement of the target member. A hollow part (160, 260) formed in the target member opens to the flange part side of the target member and extends from an opening to the protrusions beyond the recesses in the axial direction.

Description

Detection device, program and control method CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is based on Japanese Application No. 2024-061735, filed on April 5, 2024, the contents of which are incorporated herein by reference.

[0002] The present disclosure relates to a detection device, a program, and a control method.

[0003] A hub bearing with a sensor that detects a load acting on the hub bearing is known, and is described in, for example, Japanese Patent Application Laid-Open No. 2003-222296.

[0004] JP 2013-140125 A

[0005] A detection device applicable to a mechanical device is known. The mechanical device includes a hub bearing. The hub bearing includes a first bearing member (e.g., an outer ring member), a second bearing member (e.g., an inner ring member), and rolling elements. The first bearing member has a first cylindrical portion extending in the axial direction, which is the direction of the rotational center axis of the hub bearing, and is fixed to a base portion. The second bearing member has a second cylindrical portion provided at a position facing the first cylindrical portion in a radial direction perpendicular to the axial direction, and a flange portion extending radially outward from the second cylindrical portion. Rolling elements are provided between the first cylindrical portion and the second cylindrical portion. As a result, the hub bearing rotatably supports the rotating body relative to the base portion.

[0006] The detection device includes a target member and a sensor substrate as components for detecting displacement or force. The sensor substrate is provided at a position offset from the flange portion in the axial direction. The target member is provided at a portion of the flange portion that faces the sensor substrate in the axial direction, and has an annular shape that extends circumferentially around the rotational center axis of the second cylindrical portion.

[0007] The sensor substrate outputs a voltage signal corresponding to the relative displacement of the target member with respect to the sensor substrate, and the displacement or force is detected based on the output voltage signal.

[0008] When the second bearing member rotates relative to the base portion, the temperature of the target member and the sensor substrate may increase due to an increase in the temperature around the target member and the sensor substrate. Therefore, a technology for suppressing the temperature increase of the target member and the sensor substrate is desired.

[0009] A primary object of the present disclosure is to provide a detection device, a program, and a control method that can suppress temperature increases in a target member and a sensor substrate.

[0010] the second bearing member has a second cylindrical portion provided at a position facing the first cylindrical portion in a radial direction perpendicular to the axial direction, and a flange portion extending radially outward from the second cylindrical portion; and rolling elements provided between the first cylindrical portion and the second cylindrical portion, and rotatably supports the second bearing member with respect to the base portion; a sensor substrate provided at a position shifted from the flange portion in the axial direction; and an annular target member provided at a portion of the flange portion facing the sensor substrate in the axial direction, and extending in a circumferential direction of the second cylindrical portion around the rotational axis, The portion of the target member facing the sensor substrate has convex portions that protrude in the axial direction relative to the flange portion and concave portions that are recessed toward the flange portion in the axial direction relative to the convex portions, alternately arranged in the circumferential direction, and the sensor substrate outputs a voltage signal corresponding to the relative displacement of the target member relative to the sensor substrate.

[0011] The target member has a hollow structure in which a hollow portion extending in the circumferential direction is formed, and the hollow portion opens on the flange portion side of the target member and extends from the opening in the axial direction beyond the recess to the protrusion.

[0012] This allows air to be exchanged in the hollow space, suppressing a temperature rise in the target member. Furthermore, because the hollow space extends beyond the recessed portion to the protruding portion, the protruding portion side of the target member can also be effectively cooled, enhancing the effect of suppressing a temperature rise in the target member. This suppresses a temperature rise in the target member and the sensor substrate disposed opposite the target member.

[0013] The above and other objects, features, and advantages of the present disclosure will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which Fig. 1 is a perspective view of a wheel unit according to a first embodiment, Fig. 2 is a longitudinal cross-sectional view of the wheel unit, Fig. 3 is a partially enlarged view of the vicinity of a hub bearing of the wheel unit, Fig. 4 is a perspective view of a target member, Fig. 5 is a perspective view of the target member, Fig. 6 is a plan view of the target member, Fig. 7 is an exploded perspective view of the wheel unit, Fig. 8 is an exploded perspective view of the wheel unit, Fig. 9 is a diagram showing the electrical configuration of a sensor board and a processing unit, Fig. 10 is a perspective view of a target member according to a second embodiment, Fig. 11 is a side view of the target member, and Fig. 12 is a plan view of a target member according to a modified example of the second embodiment. FIG. 14 is a perspective view of the first and second divided members according to a modified example of the second embodiment; FIG. 15 is a diagram showing the electrical configuration of the sensor board and processing unit according to the third embodiment; FIG. 16 is a flowchart showing the procedure for overheat protection processing; FIG. 17 is a timing chart showing the time changes in the temperature of the excitation coil and the amplitude of the excitation voltage; FIG. 18 is a diagram showing the time changes in the voltage induced in the receiving coil; FIG. 19 is a flowchart showing the procedure for overheat protection processing according to the fourth embodiment; and FIG. 20 is a flowchart showing the procedure for load calculation processing.

[0014] Several embodiments will be described with reference to the drawings. In several embodiments, functionally and / or structurally corresponding and / or associated parts may be designated by the same reference numerals or reference numerals that differ in the hundredth or more digit. For corresponding and / or associated parts, reference may be made to the descriptions of other embodiments.

[0015] First Embodiment A first embodiment of a detection device according to the present disclosure will be described below with reference to the drawings. The detection device of this embodiment is configured to be capable of calculating a force acting on a wheel (drive wheel or driven wheel) as a rotating body. The vehicle equipped with wheels is, for example, a four-wheeled passenger vehicle (for example, private or commercial use) having two front wheels and two rear wheels. However, the vehicle is not limited to this, and may be a vehicle other than a four-wheeled vehicle, such as a two-wheeled vehicle. Furthermore, the use of the vehicle is not limited to passenger use.

[0016] The wheel unit 10 as a mechanical device will be described using Figures 1 to 9. Figure 1 is a perspective cross-sectional view of the wheel unit 10 cut along a plane that passes through the center of rotation of the wheel unit 10 and extends vertically, and Figures 2 and 3 are longitudinal cross-sectional views of the wheel unit 10.

[0017] As shown in Figures 1 and 2, the wheel unit 10 includes a wheel 11 and a tire 14 that constitute a wheel. The wheel 11 includes a cylindrical rim portion 12 and a disc portion 13 provided at the outer end of the rim portion 12 in the vehicle width direction. The disc portion 13 includes a disc mounting portion 18 located in the center of the disc portion 13 and spoke portions 19 extending radially from the disc mounting portion 18 to the rim portion 12. The tire 14 is mounted on the outer periphery of the rim portion 12.

[0018] As shown in Figures 1, 2, and 7, the wheel unit 10 includes a brake device 20 and a hub bearing 40. The brake device 20 is a disc-type friction braking device and includes a disc rotor 21 that is circular as a whole and a brake caliper 33. The brake caliper 33 is actuated by hydraulic pressure, an electric signal, or the like, and includes a pair of disc pads that contact the disc rotor 21 to generate braking force, a piston that presses the disc pads against the disc rotor 21, and a caliper body that supports the brake pads and the piston. As shown in Figure 7, the brake caliper 33 is fixed to the knuckle 15, which serves as a base, with bolts 34.

[0019] In the following, the direction in which the rotational center axis of the hub bearing 40 (specifically, for example, the inner ring member 60 of the hub bearing 40) extends is referred to as the axial direction, the direction extending radially from the rotational center axis is referred to as the radial direction, and the direction extending circumferentially around the rotational center axis is referred to as the circumferential direction.

[0020] The disc rotor 21 of this embodiment is a ventilated disc having an internal cavity for ventilation. The disc rotor 21 has a hat portion 22 and a sliding portion 23. The hat portion 22 is attached to the hub bearing 40. The hat portion 22 has a disk-shaped bottom surface portion 24 and a disc peripheral wall portion 25. A mounting hole 26 is formed in the center of the bottom surface portion 24. Bolt insertion holes 27 that axially penetrate the bottom surface portion 24 are formed in a circumferential direction around the mounting hole 26. The disc rotor 21 is connected to the hub bearing 40 using the mounting hole 26 and the bolt insertion holes 27. The disc peripheral wall portion 25 is cylindrical and extends from the outer circumferential edge of the bottom surface portion 24, forming the peripheral surface of the hat portion 22.

[0021] A sliding portion 23 is connected to the end of the disk peripheral wall portion 25 opposite the bottom surface portion 24. The sliding portion 23 is formed to protrude outward in an annular shape from the disk peripheral wall portion 25. The front and back surfaces of the sliding portion 23 form a pair of sliding surfaces that are pressed against the disk pad.

[0022] The sliding portion 23 includes an inner disk portion 28, an outer disk portion 29 disposed on the outer side of the inner disk portion 28, and fins 30. The fins 30 connect the inner disk portion 28 and the outer disk portion 29 at multiple locations in the circumferential direction. The fins 30 extend radially, and the space surrounded by the inner disk portion 28, the outer disk portion 29, and the fins 30 forms an air passage 30a penetrating in the radial direction (diameter direction). The air passage 30a is a passage extending from an air intake port 31 formed on the radially inner side of the sliding portion 23 to an air exhaust port 32 formed on the radially outer side.

[0023] The hub bearing 40 is a rolling bearing (specifically, a radial ball bearing) and includes an outer ring member 50 (corresponding to the "first bearing member"), an inner ring member 60 (corresponding to the "second bearing member"), and a plurality of rolling elements 41 (specifically, balls) arranged between the outer ring member 50 and the inner ring member 60. The hub bearing 40 of this embodiment has a structure in which the rolling elements 41 are arranged in two rows in the axial direction. Note that the hub bearing 40 may also be a radial roller bearing provided with rollers as the rolling elements 41.

[0024] The inner ring member 60 includes an inner cylindrical portion 61 (corresponding to the "second cylindrical portion") extending in the axial direction, and a flange portion 62 extending radially from a first end of the inner cylindrical portion 61 in the axial direction. The outer ring member 50 includes an outer cylindrical portion 51 (corresponding to the "first cylindrical portion") provided at a position facing radially outward from the inner cylindrical portion 61. A rolling element 41 is provided between the outer cylindrical portion 51 and the inner cylindrical portion 61.

[0025] A shaft insertion hole 63 is formed in the inner cylindrical portion 61, penetrating in the axial direction. Splines are formed on the inner peripheral surface of the shaft insertion hole 63. A shaft (not shown) is fitted into the shaft insertion hole 63 to transmit rotational power from a driving power source such as a motor.

[0026] The flange portion 62 is disk-shaped and extends radially outward beyond the outer cylindrical portion 51. The flange portion 62 has a plurality of bolt insertion holes 64 arranged in the circumferential direction, through which the hub bolts 17 for fixing the wheel 11 are inserted. In this embodiment, as shown in FIG. 8 , for example, five hub bolts 17 are arranged in the circumferential direction. Therefore, five bolt insertion holes 64 are also formed. The hub bolts 17 are made of a magnetic material, and more specifically, are made of iron, a soft magnetic material.

[0027] As shown in Figure 3, the disk mounting portion 18 has a bolt insertion hole 18a formed therethrough in the axial direction. With the bottom surface portion 24 of the disk rotor 21 and the disk mounting portion 18 overlapping the mounting surface 62b of the flange portion 62, a hub bolt 17 is inserted into the bolt insertion holes 27, 18a. A nut 35 is threaded onto the male thread of the hub bolt 17, thereby fixing the disk mounting portion 18 and the disk rotor 21 to the hub bearing 40. This makes the target member 80, disk rotor 21, and inner ring member 60 coaxial, and the target member 80, disk rotor 21, and wheel 11 rotate together.

[0028] The wheel unit 10 is provided with a dust cover 70, which is a heat shield. The dust cover 70 is provided on the inner side in the vehicle width direction of the hub bearing 40 and the sliding portion 23 of the disc rotor 21. The dust cover 70 extends radially outward beyond the outer peripheral edge of the sliding portion 23.

[0029] The wheel unit 10 includes a detection device. The detection device is provided in the inner space of the wheel 11 and includes a target member 80 and a sensor substrate 100. The detection device detects the rotational speed of the wheel consisting of the wheel 11 and tire 14, the lateral force Fy acting between the ground contact surface (ground) GL and the wheel (specifically, the tire 14), and the force acting between the ground contact surface GL and the wheel in a direction perpendicular to the ground contact surface GL (hereinafter referred to as a vertical load Fz). The direction in which the lateral force acts is perpendicular to the direction in which the vertical load acts. For example, the calculated rotational speed, lateral force, and vertical load are used in a control device (specifically, an ECU: Electronic Control Unit) provided in the vehicle to control the vehicle's running, which is a moving object. The structure of the detection device will be described below.

[0030] The target member 80 is made of a metal material (e.g., aluminum or iron). In this embodiment, the target member 80 is made of aluminum. The target member 80 is a separate member from the hub bearing 40. The target member 80 includes a detection object portion 81. The detection object portion 81 is provided axially opposite the sensor board 100 without contacting the sensor board 100, and has an annular shape extending circumferentially around the central axis of rotation of the hub bearing 40. A bearing insertion hole 82 is formed in the center of the target member 80. The inner cylindrical portion 61 is inserted into the bearing insertion hole 82. The target member 80 is fixed to the flange portion 62, for example, by a fastener such as a bolt (not shown). This allows the inner ring member 60 of the hub bearing 40 and the target member 80 to rotate integrally.

[0031] The target member 80 is provided radially inward of the disk peripheral wall portion 25 that constitutes the disk rotor 21. This allows the disk rotor 21 to protect against foreign matter from the outside.

[0032] The detection target portion 81 has protrusions 83 arranged in a circumferential direction, protruding from the flat surface of the detection target portion 81 in the axial direction (inward in the vehicle width direction). Recesses 84 are formed between the protrusions 83 arranged in the circumferential direction. The protrusions 83 and recesses 84 are arranged alternately in the circumferential direction. The surface of the protrusions 83 is a flat surface 83a, and the surface of the recesses 84 is a flat surface 84a. In this embodiment, 12 pairs of protrusions 83 and recesses 84 are provided. The circumferential length of the multiple protrusions 83 is equal to the circumferential length of the multiple recesses 84.

[0033] In this embodiment, the target member 80 is divided into two parts in the circumferential direction, as shown in Figures 4 and 5, more specifically, the two parts are divided into two parts with equal circumferential lengths. The reason for dividing the target member 80 is to facilitate the assembly of the target member 80 to the hub bearing 40. For example, the target member 80 can be attached to a completed hub bearing 40 later. Hereinafter, one of the divided parts of the target member 80 will be referred to as a first divided part 80A, and the other part will be referred to as a second divided part 80B.

[0034] Next, the sensor substrate 100 will be described.

[0035] The sensor board 100 is a so-called eddy current inductive sensor. The sensor board 100 is disposed with its plate surface extending in the vertical direction. The sensor board 100 is disposed in an arrangement space that is adjacent to the flange portion 62 on the inner side in the vehicle width direction and that is radially outward of the inner cylindrical portion 61 and the outer cylindrical portion 51. In the arrangement space, a target member 80 is disposed at a position axially opposite the sensor board 100. In this embodiment, the sensor board 100 is disposed at a position axially opposite the upper end of the target member 80. The sensor board 100 is disposed between the flange portion 62 and the hub mounting portion 52.

[0036] The sensor substrate 100 has an arc shape that follows the target member 80. As shown in FIG. 9 , the sensor substrate 100 includes an excitation coil 110 and a receiving coil. In this embodiment, the receiving coils are a first receiving coil 111 and a second receiving coil 112. Each of the coils 110 to 112 is a planar coil that follows the surface of the sensor substrate 100. The sensor substrate 100 is a multi-layer substrate. Each of the coils 110 to 112 is formed by wiring patterns, vias, and the like that are formed on each layer of the sensor substrate 100.

[0037] The sensor board 100 includes an excitation circuit 113 that supplies a high-frequency excitation voltage to the excitation coil 110, and a receiving circuit 114. When an excitation voltage is supplied to the excitation coil 110, an excitation current flows through the excitation coil 110, and a voltage having the same or equivalent frequency as the excitation voltage is induced in each of the coils 111, 112. The receiving circuit 114 detects output voltage signals at both ends of each of the coils 111, 112. When an excitation voltage is supplied to the excitation coil 110, the phase difference between the first output voltage signal of the first receiving coil 111 and the output voltage signal of the second receiving coil 112 is 90 degrees.

[0038] In this embodiment, the coils 110 to 112 have the same circumferential center position, which faces the upper end or lower end of the target member 80 in the axial direction.

[0039] The sensor board 100 is provided with a connector 115 electrically connected to the excitation circuit 113 and the receiving circuit 114. The connector 115 is electrically connected to a processing unit 117 via a cable 116. The processing unit 117 may be provided on the vehicle body or may be built into the wheel unit 10.

[0040] The processing unit 117 includes a central processing unit (CPU). The functions of the processing unit 117 can be provided by software stored in a physical memory device and a computer executing the software, software alone, hardware alone, or a combination thereof. For example, if the microcomputer of the processing unit 117 is provided by a hardware electronic circuit, the function can be provided by a digital circuit including multiple logic circuits or an analog circuit. For example, the microcomputer executes a program stored in a non-transitory tangible storage medium serving as its own storage unit. The program includes, for example, a program for a load calculation process, which will be described later. A set of instructions constituting the program is executed to perform a method corresponding to the program. The storage unit is, for example, a non-volatile memory. The program stored in the storage unit can be updated via a communication network, such as the Internet, via over-the-air (OTA) or other means.

[0041] Next, the load calculation process will be described.

[0042] 2, when a lateral force Fy acts on the wheel, the inclination of the central axis of the inner ring member 60 relative to the central axis of the outer ring member 50 increases. In this case, the axial distance between each of the coils 111, 112 and the target member 80 changes, and the amplitude of the output voltage signals of each of the coils 111, 112 changes. The processing unit 117 calculates the axial displacement ΔY of the target member 80 based on this change in amplitude, and performs processing to calculate the lateral force Fy based on the calculated axial displacement ΔY.

[0043] On the other hand, when a vertical load Fz acts on the wheel, the central axis of the inner ring member 60 is displaced in a direction perpendicular to the central axis of the outer ring member 50. As a result, the target member 80 fixed to the flange portion 62 is also displaced. In this case, the sensor board 100 is configured so that the amplitude of the output voltage signals of the first receiving coil 111 and the second receiving coil 112 changes. Based on this change in amplitude, the processing unit 117 calculates the displacement of the target member 80 in a direction perpendicular to the axial direction and the vehicle length direction (hereinafter referred to as the vertical displacement ΔZ), and performs processing to calculate the vertical load Fz based on the calculated vertical displacement ΔZ.

[0044] The processing unit 117 calculates the rotation angle of the wheel based on the output signal of at least one of the first receiving coil 111 and the second receiving coil 112. The processing unit 117 calculates the rotation speed of the wheel based on the calculated rotation angle. Specifically, for example, the processing unit 117 may calculate the rotation speed based on the time differential value of the rotation angle.

[0045] The sensor substrate 100 and the load calculation process are described in, for example, Japanese Patent Application Laid-Open No. 2023-130285.

[0046] 7 and 8, a configuration for fixing the sensor board 100 to the knuckle 15 will be described. For convenience, the target member 80 and other components are not shown in FIGS.

[0047] The wheel unit 10 includes a board mounting member 120 as a component for fixing the sensor board 100 to the knuckle 15. The board mounting member 120 is plate-shaped and annular. The board mounting member 120 is made of, for example, synthetic resin or a metal material (e.g., aluminum). A circular (specifically, perfect circular) through-hole 122 is formed in the center of the board mounting member 120. The through-hole 122 penetrates axially from the first plate surface 121 a to the second plate surface 121 b of the board mounting member 120, and the outer cylindrical portion 51 is fitted into the through-hole 122.

[0048] A protrusion 130 to which the sensor board 100 is attached is formed on the first plate surface 121a of the board mounting member 120. The protrusion 130 extends from the first plate surface 121a toward the flange portion 62 in the axial direction. A plurality of protrusions 130 (three are illustrated in the figure) are formed spaced apart in the circumferential direction. Of the plurality of protrusions 130, the protrusions 130 at both ends in the circumferential direction are protrusions for attaching both ends of the sensor board 100 in the circumferential direction. Of the plurality of protrusions 130, the protrusion 130 sandwiched between the protrusions 130 at both ends in the circumferential direction is a protrusion for attaching an intermediate portion of the sensor board 100 in the circumferential direction.

[0049] Each protrusion 130 has a bolt insertion hole 132 formed therethrough in the axial direction, through which a board mounting bolt 131 is inserted. Meanwhile, the sensor board 100 has the same number of female threaded holes 101 as the bolt insertion holes 132, into which the male threads of the board mounting bolts 131 are screwed.

[0050] The board mounting member 120 and the sensor board 100 have a configuration that facilitates relative positioning of the sensor board 100 with respect to the board mounting member 120. More specifically, the sensor board 100 has a first plate surface 102a and a second plate surface 102b that is the back surface of the first plate surface 102a. Positioning pins 103 that extend axially toward the board mounting member 120 are provided on both circumferential ends of the second plate surface 102b. Of the multiple protrusions 130, the protrusions 130 on both circumferential ends are formed with pin holes 133 that extend axially and through which the positioning pins 103 are inserted.

[0051] By inserting the positioning pins 103 into the pin holes 133, the female screw holes 101 at both circumferential ends of the sensor board 100 are aligned with the bolt insertion holes 132 of the protrusions 130. In this aligned state, the board mounting bolts 131 are inserted into the bolt insertion holes 132 from the second plate surface 121b side of the board mounting member 120, and the male threads of the board mounting bolts 131 are screwed into the female screw holes 101. As a result, the sensor board 100 is fixed to the board mounting member 120 while maintaining a predetermined relative positional relationship between the sensor board 100 and the board mounting member 120. In this case, the plate surfaces of the sensor board 100 and the board mounting member 120 are parallel to each other. Furthermore, the sensor board 100 is supported by the protrusions 130 while spaced apart from the first plate surface 121a of the board mounting member 120.

[0052] The board mounting member 120 has bolt insertion holes 123 formed therein, each of which penetrates from the first plate surface 121 a to the second plate surface 121 b and through which a bolt 16 is inserted. In this embodiment, three bolt insertion holes 123 are formed and spaced apart in the circumferential direction.

[0053] An extension 124 extending axially toward the dust cover 70 is formed on the periphery of the through hole 122 of the board mounting member 120. The extension 124 is formed over the entire periphery of the periphery of the through hole 122.

[0054] The dust cover 70 includes a first wall portion 73, a connecting portion 74, and a second wall portion 75. The connecting portion 74 extends radially outward from the radially outer end portion of the first wall portion 73. The second wall portion 75 extends radially outward from the radially outer end portion of the connecting portion 74.

[0055] The first wall portion 73 of the dust cover 70 has a circular (specifically, perfect circular) through-hole 72 formed therein, which extends in a direction perpendicular to the plate surface of the first wall portion 73 and into which the extension portion 124 of the board mounting member 120 is fitted. The knuckle 15 has a circular (specifically, perfect circular) through-hole 15a formed therein, which extends in the axial direction and into which the outer cylindrical portion 51 of the outer ring member 50 is fitted.

[0056] A bolt insertion hole 71 through which the bolt 16 is inserted is formed in the first wall portion 73 of the dust cover 70. A bolt insertion hole 15b through which the bolt 16 is inserted is formed in the knuckle 15.

[0057] The hub bearing 40 has hub mounting portions 52, the number of which is the same as the number of bolt insertion holes 123. The hub mounting portions 52 are spaced apart in the circumferential direction. Each hub mounting portion 52 has a female threaded hole 52a that penetrates in the axial direction and into which the bolt 16 is screwed. Each hub mounting portion 52 has a flat surface 52b that extends in a direction perpendicular to the axial direction.

[0058] In a front view of the plate surface of board mounting member 120, sensor board 100 and bolt insertion holes 123 are disposed at positions that do not overlap. Furthermore, in a front view of the plate surface of board mounting member 120, hub mounting portion 52 and bolt insertion holes 123 are disposed at positions that do not overlap in the circumferential direction. This prevents sensor board 100 from interfering with hub mounting portion 52 when first plate surface 121a of board mounting member 120, with sensor board 100 attached, is brought into contact (specifically, surface contact) with flat surface 52b of hub mounting portion 52.

[0059] The first plate surface 121a of the board mounting member 120 abuts against the flat surface 52b, and the outer cylindrical portion 51 is fitted into the through hole 122. As a result, the central axis of the inner ring member 60 and the center of the through hole 122 are aligned.

[0060] The board mounting member 120, the dust cover 70, and the knuckle 15 are configured to facilitate relative positioning of the dust cover 70 and the knuckle 15 with respect to the board mounting member 120. More specifically, the knuckle 15 is provided with a positioning pin 15c that extends axially toward the board mounting member 120. The first wall portion 73 of the dust cover 70 is formed with a pin hole 76 that extends axially and through which the positioning pin 15c is inserted. The board mounting member 120 is formed with a pin hole 126 that extends axially and through which the positioning pin 15c is inserted.

[0061] The end of the through hole 15a of the knuckle 15 on the PCB mounting member 120 side in the axial direction is an expanded diameter portion 15d with an expanded radial dimension. The positioning pin 15c is inserted into the pin holes 76, 126, and the extension portion 124 of the PCB mounting member 120 is fitted into the expanded diameter portion 15d. This aligns the centers of the through holes 15a, 72, 122. The extension portion 124 and the expanded diameter portion 15d can improve the alignment accuracy.

[0062] The board mounting member 120, the first wall portion 73 of the dust cover 70, and the knuckle 15 are formed with cable insertion holes 127, 77, and 15e through which the cable 116 connected to the connector 115 of the sensor board 100 is inserted.

[0063] Next, the target member 80 will be described with reference to FIGS.

[0064] The target member 80 includes an outer peripheral wall portion 140 and an inner peripheral wall portion 150. The outer peripheral wall portion 140 extends from the entire circumferential area of ​​the outer peripheral edge portion of the detection target portion 81 in the axial direction toward the flange portion 62. The inner peripheral wall portion 150 extends from the entire circumferential area of ​​the inner peripheral edge portion of the detection target portion 81 in the axial direction toward the flange portion 62.

[0065] The target member 80 and the sensor substrate 100 are disposed in a space radially inward of the disk rotor 21. Frictional heat generated at the sliding portion 23 of the disk rotor 21 tends to raise the temperature in this space. The target member 80 of this embodiment has a structure that suppresses the temperature rise in this space.

[0066] Specifically, the target member 80 has a hollow structure in which an annular hollow portion 160 is formed extending over the entire circumferential direction. The hollow portion 160 is a portion having a space surrounded by the outer peripheral wall portion 140, the inner peripheral wall portion 150, and the detection target portion 81. As a result, the hollow portion 160 opens on the flange portion 62 side of the target member 80, as shown in FIG. 5 . The hollow portion 160 also extends from this opening in the axial direction beyond the flat surface 84a of the recessed portion 84 to the protruding portion 83. The divided members 80A, 80B constituting the target member 80 may be formed, for example, by pressing an aluminum plate.

[0067] The target member 80 is disposed in a space radially inside the disk rotor 21. As the disk rotor 21 rotates, an airflow is generated from the air intake 31 to the air outlet 32, creating an airflow in the space radially inside the disk rotor 21. This causes air to flow into and out of the hollow portion 160 of the target member 80 through the gap between the flange portion 62 and the target member 80. As a result, the air in the hollow portion 160 is replaced, and a temperature rise in the target member 80 can be suppressed. This suppresses a temperature rise in the space radially inside the disk rotor 21, and also a temperature rise in the sensor substrate 100. As a result, overheating abnormalities in the sensor substrate 100 can be suppressed, and a decrease in load calculation accuracy can be suppressed.

[0068] Second Embodiment A second embodiment will be described below with reference to the drawings, focusing on differences from the first embodiment. In this embodiment, the structure of the target member 80 is modified as shown in Figures 10 and 11. Figure 10 is a perspective view of the target member 180, and Figure 11 is a side view of the target member 180.

[0069] Similar to the first embodiment, the target member 180 includes a detection target portion 181, an outer peripheral wall portion 240, and an inner peripheral wall portion 250. Similar to the first embodiment, the detection target portion 181 has convex portions 183 and concave portions 184 alternately provided in the circumferential direction. The surface of the convex portion 183 is a flat surface 183a, and the surface of the concave portion 184 is a flat surface 184a. The portion having the space surrounded by the outer peripheral wall portion 240, the inner peripheral wall portion 250, and the detection target portion 181 is a hollow portion 260.

[0070] The target member 180 is formed with a bearing insertion hole 182 through which the inner cylindrical portion 61 is inserted. The target member 180 is divided into two parts in the circumferential direction, more specifically, the two parts are divided into two parts with equal circumferential lengths. One of the divided parts of the target member 180 is a first divided part 180A, and the other part is a second divided part 180B.

[0071] An outer opening 241 that connects to the hollow portion 260 is formed in the outer peripheral wall portion 240. A plurality of outer openings 241 are formed at predetermined intervals in the circumferential direction. Furthermore, an inner opening 251 that connects to the hollow portion 260 is formed in the inner peripheral wall portion 250. A plurality of inner openings 251 are formed at predetermined intervals in the circumferential direction. The outer openings 241 and the inner openings 251 promote air exchange in the hollow portion 260. As a result, the effect of suppressing a temperature rise in the target member 180 can be enhanced. In this embodiment, each opening 241, 251 corresponds to a "circumferential wall opening."

[0072] In this embodiment, the outer opening 241 and the inner opening 251 extend in the axial direction from the end of the target member 180 on the flange portion 62 side toward the detection object portion 81 side. This allows the opening areas of the outer opening 241 and the inner opening 251 to be increased, thereby further improving the effect of suppressing the temperature rise of the target member 180.

[0073] In this embodiment, the outer opening 241 and the inner opening 251 are formed in the outer peripheral wall portion 240 and the outer opening 241 at the peripheral wall portion that corresponds to each of the convex portions 183 in the circumferential direction. Therefore, the axial dimension H1 of the outer opening 241 and the inner opening 251 can be made larger than the axial dimension H2 from the end of the target member 180 on the flange portion 62 side to the flat surface 184a of the recess 184. In other words, the opening areas of the outer opening 241 and the inner opening 251 can be made larger. As a result, the effect of suppressing the temperature rise of the target member 180 can be further improved.

[0074] Modification of Second Embodiment The outer opening 241 and the inner opening 251 may be formed in a peripheral wall portion of the outer peripheral wall portion 240 and the outer opening 241 that corresponds to the recess 184 in the circumferential direction.

[0075] An opening may be formed in only one of the outer opening 241 and the inner opening 251 .

[0076] The openings connecting to the hollow portion are not limited to those exemplified in the second embodiment, and may be openings 161 formed in the step portions between the convex portions 83 and the concave portions 84, as shown in FIG. 12 . In this case, it is easier to guide the airflow from the openings 161 to the hollow portion, and the circumferential airflow in the hollow portion can be promoted. This enhances the effect of suppressing the temperature rise of the target member 80. The openings 161 may be provided in only one or both of the step portions at both circumferential ends of each convex portion 83.

[0077] 13 and 14 may also be employed as a configuration for forming an opening in the step portion. The first and second divided members 80A and 80B shown in FIGS. 13 and 14 are members in which end openings 85 are formed at the ends of the first and second divided members 80A and 80B shown in FIGS. 4 and 5 in the circumferential direction that face the convex portion 83. The end openings 85 extend from the ends of the first and second divided members 80A and 80B that face the flange portion 62, past the flat surface 84a of the recess 84, to the convex portion 83. For convenience, the degree of protrusion of the convex portion 83 is shown in FIGS. 13 and 14 to be greater than that shown in FIG. 4.

[0078] The end of each circumferential end of the first divided member 80A that faces the convex portion 83 is brought into contact with the end of each circumferential end of the second divided member 80B that faces the concave portion 84, and the end of each circumferential end of the first divided member 80A that faces the concave portion 84 is brought into contact with the end of each circumferential end of the second divided member 80B that faces the convex portion 83. This forms the target member 80 shown in FIG. 13. In this case, part of the end opening 85 becomes an opening formed in the step between the convex portion 83 and the concave portion 84.

[0079] Third Embodiment A third embodiment will now be described with reference to the drawings, focusing on differences from the first and second embodiments. In this embodiment, when the temperature of the sensor substrate 100 exceeds a threshold value, the amplitude VCC of the excitation voltage applied to the excitation coil 110 is reduced in order to reduce the temperature of the sensor substrate 100.

[0080] In this embodiment, as shown in FIG. 15 , the sensor substrate 100 includes a temperature sensor 200. The temperature sensor 200 detects the temperature of at least one of the excitation coil 110, the first receiving coil 111, and the second receiving coil 112, for example. The processing unit 117 includes a voltage control unit 210, a displacement calculation unit 211, a force calculation unit 212, and a rotational speed calculation unit 213. The voltage control unit 210 controls the excitation voltage applied to the excitation coil 110 to excite the excitation coil 110. The displacement calculation unit 211 calculates the axial displacement ΔY and the vertical displacement ΔZ of the target member 80. The force calculation unit 212 calculates the lateral force Fy based on the axial displacement ΔY calculated by the displacement calculation unit 211. The force calculation unit 212 also calculates the vertical load Fz based on the vertical displacement ΔZ calculated by the displacement calculation unit 211. The rotational speed calculation unit 213 calculates the rotational speed of the wheel.

[0081] When the load calculation process is executed, an excitation voltage is applied to the excitation coil 110. In this case, there is a concern that the sensor substrate 100 (e.g., the excitation coil 110) may overheat depending on the ambient environment and usage conditions of the detection device. Therefore, the voltage control unit 210 performs overheat protection processing to prevent the sensor substrate 100 from overheating. FIG. 16 is a flowchart showing the procedure of the overheat protection processing. This processing is executed by the voltage control unit 210 while the load calculation process is being executed. In an initial state, the voltage control unit 210 applies an excitation voltage whose amplitude is an initial amplitude Vini to the excitation coil 110.

[0082] In step S10, the temperature Tr of the sensor substrate 100 is acquired. In this embodiment, the temperature Tr of the sensor substrate 100 is a detection value of the temperature sensor 200.

[0083] In step S11, it is determined whether the temperature Tr of the sensor substrate 100 is greater than a threshold value Tth. The threshold value Tth is set, for example, to a value equal to or less than a limit temperature Tlim, which is the upper limit temperature tolerance of the sensor substrate 100. If it is determined in step S11 that the temperature Tr of the sensor substrate 100 is equal to or less than the threshold value Tth, the process proceeds to step S12. In step S12, the amplitude VCC of the excitation voltage applied to the excitation coil 110 is maintained at the initial amplitude Vini.

[0084] If it is determined in step S11 that the temperature Tr of the sensor substrate 100 is greater than the threshold value Tth, the process proceeds to step S13, where an overheat protection process is performed to reduce the amplitude VCC of the excitation voltage.

[0085] The overheat protection process will be described in detail with reference to Fig. 17. At time t0 in Fig. 17, the temperature Tr of the sensor substrate 100 exceeds the threshold value Tth. In this case, the voltage control unit 210 gradually reduces the amplitude VCC of the excitation voltage to a low amplitude VL, as shown by the solid line.

[0086] The low amplitude VL is calculated, for example, by the following method. FIG. 18 shows the time change of the output voltage signal at both ends of the first receiving coil 111 or the second receiving coil 112 (hereinafter referred to as the receiving coil). In FIG. 18, Vcen represents the median value of the output voltage signal at both ends of the receiving coil. When an excitation voltage is supplied to the excitation coil 110, a high-frequency voltage centered on the median value Vcen is induced in the receiving coil. As the amplitude VCC of the excitation voltage decreases from the initial amplitude Vini to the low amplitude VL, the amplitude of the voltage induced in the receiving coil decreases. When the amplitude of the voltage induced in the receiving coil decreases, the sensitivity of the lateral force Fy and the vertical load Fz calculated based on the voltage induced in the receiving coil may decrease. Here, the lateral force Fy and the vertical load Fz are used, for example, to control the vehicle in which the detection device is installed. Therefore, the voltage control unit 210 calculates the low amplitude VL so that the sensitivity of the lateral force Fy and the vertical load Fz falls within a range allowable for control of the vehicle in which the detection device is installed.

[0087] The wheel rotation speed is calculated based on the timing at which the output voltage signal of at least one of the first receiving coil 111 and the second receiving coil 112 reaches a specific value (e.g., 0). Therefore, the effect of a reduction in the excitation voltage amplitude VCC on the calculated wheel rotation speed is smaller than the effect of a reduction in the excitation voltage amplitude VCC on the calculated values ​​of the lateral force Fy and the vertical load Fz. Therefore, when calculating the low amplitude VL, the voltage control unit 210 may consider only the effect of a reduction in the excitation voltage amplitude VCC on the calculated values ​​of the lateral force Fy and the vertical load Fz.

[0088] Furthermore, the voltage control unit 210 may calculate the low amplitude VL based on the temperature Tr of the sensor substrate 100. In this case, for example, the higher the temperature Tr of the sensor substrate 100, the smaller the value of the low amplitude VL calculated by the voltage control unit 210. As a result, for example, when the temperature Tr of the sensor substrate 100 is close to the limit temperature Tlim, the rate at which the temperature Tr of the sensor substrate 100 decreases can be increased.

[0089] 17, at time t1, the temperature Tr of the sensor substrate 100 becomes equal to or lower than the threshold value Tth. In this case, the voltage control unit 210 gradually increases the amplitude VCC from the low amplitude VL.

[0090] According to the present embodiment described above, overheating of the sensor substrate 100 can be suppressed.

[0091] <Modification of Third Embodiment> After a positive determination is made in step S11 in FIG. 16, the threshold value used in determining whether to proceed from step S11 to step S12 may be a value smaller than the threshold value Tth.

[0092] The temperature of the sensor substrate 100 is not limited to the value detected by the temperature sensor 200, but may be an estimated value. In this case, the processing unit 117 includes a temperature estimation unit, and the temperature of the sensor substrate 100 is estimated in the temperature estimation unit based on, for example, the current flowing through the excitation coil 110.

[0093] In the overheat protection process in step S13, the voltage control unit 210 may stop the voltage supply to the excitation coil 110 and set the excitation voltage to zero.

[0094] When the amplitude VCC is reduced at time t0 in FIG. 17, the amplitude VCC may be reduced in a stepwise manner to a low amplitude VL, as indicated by the broken line.

[0095] Fourth Embodiment A fourth embodiment will be described below with reference to the drawings, focusing on differences from the third embodiment. In this embodiment, when the voltage control unit 210 executes the overheat protection process, it notifies the displacement calculation unit 211 or the force calculation unit 212 of this fact. Upon receiving the notification, the displacement calculation unit 211 or the force calculation unit 212 calculates the displacement or the force based on the amplitude VCC of the reduced excitation voltage.

[0096] 19 , after steps S10 and S11 are executed, in step S20, the voltage control unit 210 reduces the amplitude VCC of the excitation voltage and notifies the displacement calculation unit 211 or the force calculation unit 212 that overheat protection processing has been executed. In the following, for convenience, the voltage control unit 210 notifies the displacement calculation unit 211 that overheat protection processing has been executed.

[0097] FIG. 20 is a flowchart showing the procedure of the load calculation process executed in the displacement calculation unit 211.

[0098] In step S30, it is determined whether a notification that the overheat protection process has been executed has been received from voltage control unit 210. If it is determined that a notification that the overheat protection process has been executed has not been received from voltage control unit 210, the process proceeds to step S31. In step S31, the axial displacement ΔY and the vertical displacement ΔZ are calculated based on the relationship between the voltage induced in the receiving coil and the axial displacement ΔY and the vertical displacement ΔZ when the amplitude VCC of the excitation voltage is the initial amplitude Vini (hereinafter, referred to as normal operation). Specifically, for example, displacement calculation unit 211 may calculate the axial displacement ΔY and the vertical displacement ΔZ based on first map information that correlates the amplitude of the voltage signal induced in the receiving coil in normal operation with the axial displacement ΔY and the vertical displacement ΔZ.

[0099] On the other hand, if it is determined that a notification that the overheat protection process has been executed has been received from the voltage control unit 210, the process proceeds to step S32. In step S32, the displacement calculation unit 211 calculates the axial displacement ΔY and the vertical displacement ΔZ based on the relationship between the voltage induced in the receiving coil and the axial displacement ΔY and the vertical displacement ΔZ when the amplitude VCC of the excitation voltage is the low amplitude VL. The displacement calculation unit 211 switches map information linking the voltage induced in the receiving coil with the axial displacement ΔY and the vertical displacement ΔZ between normal operation and when the overheat protection process is executed. Specifically, for example, the displacement calculation unit 211 may calculate the axial displacement ΔY and the vertical displacement ΔZ based on second map information linking the amplitude of the voltage signal induced in the receiving coil with the axial displacement ΔY and the vertical displacement ΔZ when the overheat protection process is executed.

[0100] 19, the voltage control unit 210 may notify the force calculation unit 212 that the overheat protection process has been executed. In this case, in steps S31 and S32, the force calculation unit 212 may calculate the lateral force Fy and the vertical load Fz based on map information that associates the amplitude of the voltage signal induced in the receiving coil with the lateral force Fy and the vertical load Fz, for example.

[0101] According to the present embodiment described above, it is possible to protect the sensor substrate 100 from overheating while suppressing a decrease in the detection accuracy of the displacement or force of the detection device.

[0102] Other Embodiments The above-described embodiments may be modified as follows.

[0103] In each of the above embodiments, the number of divisions of the target member is not limited to two, and may be, for example, three or four (e.g., equally divided in the circumferential direction). Also, the target member may be composed of a single member.

[0104] In the second embodiment, the openings formed in the outer opening 241 and the inner opening 251 are not limited to those extending from the end of the target member 180 on the flange portion 62 side, and may be, for example, one or more through holes.

[0105] In the first and second embodiments, the hollow portion is not limited to being annular and extending over the entire circumferential direction, but may be arc-shaped and extending over a portion of the circumferential direction.

[0106] In the first and second embodiments, if the axial distance between the flat surfaces 84a, 184a of the recesses 84, 184 and the flat surfaces 83a, 183a of the convex portions 83, 183 is a predetermined distance (e.g., 5 mm) or more, a through hole connecting to the hollow portions 160, 260 may be formed in the portion of the recesses 84, 184 facing the sensor substrate 100.

[0107] The sensor board 100 may be attached to the outer ring member 50 instead of the board attachment member 120 .

[0108] The hub bearing is not limited to an inner ring rotation type, and may be an outer ring rotation type. Specifically, the inner ring axial member (corresponding to the "first bearing member") constituting the outer ring rotation type hub bearing has an inner cylindrical portion (corresponding to the "first cylindrical portion") extending in the axial direction and is fixed to the knuckle 15. The outer ring axial member (corresponding to the "second bearing member") constituting the hub bearing has an outer cylindrical portion (corresponding to the "second cylindrical portion") provided radially outside the inner cylindrical portion, and a flange portion extending radially from the outer cylindrical portion and to which the wheel is fixed.

[0109] The circumferential center positions of the first and second receiving coils 111, 112 may be located axially opposite the right or left end of the target member 80, rather than axially opposite the upper end of the target member 80. In this case, the sensor board 100 can calculate the force acting between the ground contact surface GL and the wheel in the vehicle length direction (hereinafter referred to as the longitudinal load Fx) instead of the vertical load Fz. The direction in which the lateral force Fy acts is perpendicular to the direction in which the longitudinal load Fx acts. The longitudinal load Fx is used by the control device to control the vehicle's running.

[0110] The disk rotor is not limited to a ventilated disk, but may be, for example, a solid disk made of a single circular plate.

[0111] The mechanical devices to which the detection device can be applied are not limited to wheel units, but may also be, for example, aircraft equipped with a propeller as a rotating body, ships equipped with a screw as a rotating body, internal combustion engines equipped with a crankshaft as a rotating body, or generators equipped with a turbine as a rotating body.

[0112] Furthermore, the rotating body is not limited to being used with the axial direction of the rotating body being horizontal, but may also be used with the axial direction being in a direction other than horizontal (for example, up and down).

[0113] Although the present disclosure has been described with reference to the embodiments, it is understood that the present disclosure is not limited to the embodiments or structures. The present disclosure also encompasses various modifications and equivalent modifications. In addition, various combinations and forms, including only one element, more than one element, or less than one element, are also within the scope and spirit of the present disclosure.

Claims

1. A detection device applied to a mechanical device (10), the mechanical device comprising: a rotating body (11, 14); and a hub bearing (40) rotatably supporting the rotating body relative to a base portion (15), the hub bearing comprising: a first bearing member (50) having a first cylindrical portion (51) extending in an axial direction that is the direction of the rotational center axis of the hub bearing and fixed to the base portion; a second bearing member (60) having a second cylindrical portion (61) provided at a position facing the first cylindrical portion in a radial direction perpendicular to the axial direction and a flange portion (62) extending radially outward from the second cylindrical portion; and rolling elements (41) provided between the first cylindrical portion and the second cylindrical portion, and a sensor substrate (100) rotatably supporting the second bearing member relative to the base portion and provided at a position offset from the flange portion in the axial direction; a target member (80, 180) provided in a portion of the flange portion facing the sensor substrate in the axial direction and having an annular shape extending circumferentially of the second cylindrical portion around the central axis of rotation, wherein the portion of the target member facing the sensor substrate has convex portions (83, 183) that protrude in the axial direction relative to the flange portion and concave portions (84, 184) that are recessed toward the flange portion in the axial direction relative to the convex portions alternately provided in the circumferential direction, the sensor substrate outputs a voltage signal corresponding to the relative displacement of the target member with respect to the sensor substrate, and the target member has a hollow structure in which a hollow portion (160, 260) extending in the circumferential direction is formed, and the hollow portion opens toward the flange portion of the target member and extends from the opening in the axial direction beyond the concave portion to the convex portion.

2. A detection device as described in claim 1, wherein the target member (180) has a peripheral wall portion (240, 250) extending from the outer peripheral edge of the target member toward the flange portion in the axial direction, and a peripheral wall opening (241, 251) connected to the hollow portion is formed in the peripheral wall portion.

3. A detection device as described in claim 2, wherein the peripheral wall opening is formed in a portion of the peripheral wall that corresponds to the protrusion in the circumferential direction, and the dimension of the peripheral wall opening in the axial direction is larger than the dimension of the recess in the axial direction.

4. A detection device as claimed in any one of claims 1 to 3, wherein the mechanical device is a wheel unit (10) having a vehicle wheel (11, 14) as the rotating body, the base portion is a knuckle (15) of the vehicle, the wheel unit has a disc rotor (21) extending in the circumferential direction around the central axis of rotation, the disc rotor having: a cylindrical disc circumferential wall portion (25) extending in the axial direction radially outside the flange portion and the sensor board, and an annular sliding portion (23) extending radially outward from the axial end of the disc circumferential wall portion, the sliding portion having an air passage (30a) formed in the sliding portion, the air passage (30a) extending from an air intake port (31) formed on the radially inside to an air exhaust port (32) formed on the radially outside, and the target member is provided radially inside the disc rotor.

5. A detection device as claimed in any one of claims 1 to 3, wherein the sensor substrate comprises an excitation coil (110) to which an AC excitation voltage is supplied, and a receiving coil (112, 111) in which a voltage is induced when an excitation voltage is supplied to the excitation coil, the receiving coil outputs a voltage signal corresponding to the relative displacement of the target member with respect to the sensor substrate, and the device is provided with a control unit (210) that controls the excitation voltage, and the control unit reduces the amplitude of the excitation voltage supplied to the excitation coil when it determines that the temperature of the sensor substrate has exceeded a threshold value.

6. The detection device described in claim 5, wherein, when the control unit determines that the temperature of the sensor substrate has exceeded the threshold value, the control unit supplies an excitation voltage to the excitation coil while reducing the amplitude of the excitation voltage below that before it determined that the threshold value had been exceeded.

7. A detection device as described in claim 6, further comprising a calculation unit (211, 212) that calculates the displacement or force acting on the rotating body based on the voltage signal output by the receiving coil, wherein the control unit notifies the calculation unit that the amplitude of the excitation voltage has been reduced when the amplitude of the excitation voltage has been reduced, and the calculation unit switches the correspondence between the voltage signal output by the receiving coil and the displacement or force acting on the rotating body depending on whether it determines that it has received a notification from the control unit or not.

8. The detection device according to claim 5, wherein the control unit reduces the excitation voltage supplied to the excitation coil to 0 when it determines that the temperature of the sensor substrate has exceeded the threshold value.

9. A program applied to a system including a mechanical device (10) and a detection device, wherein the mechanical device includes a rotating body (11, 14), and a hub bearing (40) that rotatably supports the rotating body relative to a base portion (15), the hub bearing having a first cylindrical portion (51) extending in an axial direction that is the direction of the rotation center axis of the hub bearing and a first bearing member (50) fixed to the base portion, a second cylindrical portion (61) provided at a position facing the first cylindrical portion in a radial direction perpendicular to the axial direction, and a flange portion (62) extending radially outward from the second cylindrical portion, and rolling elements (41) provided between the first cylindrical portion and the second cylindrical portion, and rotatably supports the second bearing member relative to the base portion, the detection device including a sensor substrate (100) provided at a position shifted from the flange portion in the axial direction, and a target member (80, 180) provided in a portion of the flange portion facing the sensor substrate in the axial direction and having an annular shape extending in a circumferential direction of the second cylindrical portion around the central axis of rotation, wherein the portion of the target member facing the sensor substrate has convex portions (83, 183) that protrude in the axial direction relative to the flange portion and concave portions (84, 184) that are recessed toward the flange portion in the axial direction relative to the convex portions are alternately provided in the circumferential direction, the sensor substrate has an excitation coil (110) to which an AC excitation voltage is supplied, and a receiving coil (112, 111) in which a voltage is induced when the excitation voltage is supplied to the excitation coil, and the receiving coil outputs a voltage signal corresponding to a relative displacement of the target member with respect to the sensor substrate, and the target member has a hollow portion (160, 182) extending in the circumferential direction.260), the hollow portion is open to the flange portion side of the target member and extends from the opening beyond the recess to the protrusion in the axial direction, and a computer (117) is caused to execute a control process for controlling the excitation voltage, and when it is determined in the control process that the temperature of the sensor substrate has exceeded a threshold value, the amplitude of the excitation voltage supplied to the excitation coil is reduced.

10. A control method applied to a system including a mechanical device (10) and a detection device, wherein the mechanical device includes a rotating body (11, 14) and a hub bearing (40) that rotatably supports the rotating body relative to a base portion (15), the hub bearing having a first cylindrical portion (51) extending in an axial direction that is the direction of the rotational center axis of the hub bearing and a first bearing member (50) fixed to the base portion, a second cylindrical portion (61) provided at a position facing the first cylindrical portion in a radial direction perpendicular to the axial direction, and a flange portion (62) extending radially outward from the second cylindrical portion, and a rolling element (41) provided between the first cylindrical portion and the second cylindrical portion, and rotatably supports the second bearing member relative to the base portion, the detection device including a sensor substrate (100) provided at a position offset from the flange portion in the axial direction, and a target member (80, 180) provided in a portion of the flange portion facing the sensor substrate in the axial direction and having an annular shape extending in a circumferential direction of the second cylindrical portion around the central axis of rotation, wherein the portion of the target member facing the sensor substrate has convex portions (83, 183) that protrude in the axial direction relative to the flange portion and concave portions (84, 184) that are recessed toward the flange portion in the axial direction relative to the convex portions are alternately provided in the circumferential direction, the sensor substrate has an excitation coil (110) to which an AC excitation voltage is supplied, and a receiving coil (112, 111) in which a voltage is induced when the excitation voltage is supplied to the excitation coil, and the receiving coil outputs a voltage signal corresponding to a relative displacement of the target member with respect to the sensor substrate, and the target member has a hollow portion (160, 182) extending in the circumferential direction.260) is formed, the hollow portion is open to the flange portion side of the target member and extends from the opening beyond the recessed portion to the protruding portion in the axial direction, and the control method includes a control step of controlling the excitation voltage, and when it is determined in the control step that the temperature of the sensor substrate has exceeded a threshold value, the control method reduces the amplitude of the excitation voltage supplied to the excitation coil.

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