JP2010090982A - Wheel bearing with sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wheel bearing with sensor accurately detecting a load placed on a wheel in any load condition without being affected by hysteresis. <P>SOLUTION: The wheel bearing includes a rolling element 5 interposed between a double row of opposed rolling faces 3 and 4 of an external member 1 and an internal member 2. One or more sensor units 20 are provided on a fixed-side member of the external member 1 and the internal member 2. The sensor unit 20 includes a distortion generation member 21 having two or more contact fixing parts to be fixed to the fixed-side member in contact therewith; and a sensor mounted on the distortion generation member 21 to detect distortion of the member 21. The contact fixing part of the member 21 is fixed to the fixed-side member by a bolt 23, and a friction reducing means 26 (27) for reducing friction between the fixed-side member and a knuckle 16 is provided. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a sensor-equipped wheel bearing with a built-in load sensor for detecting a load applied to a bearing portion of the wheel.

As a technique for detecting a load applied to each wheel of an automobile, a sensor-equipped wheel bearing that detects a load by detecting a distortion of an outer diameter surface of a flange portion of an outer ring that is a fixed ring of a wheel bearing has been proposed ( For example, Patent Document 1). There has also been proposed a wheel bearing in which a strain gauge is attached to the outer ring of the wheel bearing to detect the strain (for example, Patent Document 2).
JP 2002-098138 A Special table 2003-530565 gazette

In the technique disclosed in Patent Document 1, distortion generated by deformation of the flange portion of the fixed ring is detected. However, the deformation of the flange portion of the fixed ring involves slipping when a force exceeding the static friction force is applied between the flange surface and the knuckle surface, so that hysteresis is generated in the output signal when a repeated load is applied. There is a problem.
For example, when the load in a certain direction with respect to the wheel bearing increases, the static friction force between the fixed ring flange surface and the knuckle surface does not slip at first, but exceeds a certain size. And it comes to slip over the static friction force. If the load is reduced in this state, it will not slip due to static friction force at first, but it will slip when it reaches a certain size. As a result, when an attempt is made to estimate the load at a portion where this deformation occurs, a hysteresis as shown in FIG. 8 occurs in the output signal. When hysteresis occurs, the detection resolution decreases.
In addition, even when the fixed ring and the knuckle are made of materials having different thermal expansion coefficients, slippage is accompanied when a force exceeding the static friction force acts between the fixed ring flange and the knuckle surface along with the temperature change. Hysteresis occurs in the output signal and the load cannot be detected accurately.

  In addition, when the strain gauge is attached to the outer ring as in Patent Document 2, there is a problem in assemblability, and if there is slippage between the strain gauge and the outer ring, the output signal of the strain gauge is distorted and a load is applied. It cannot be detected accurately.

  An object of the present invention is to provide a sensor-equipped wheel bearing capable of accurately detecting a load applied to a wheel under any load condition without being affected by hysteresis.

The sensor-equipped wheel bearing according to the present invention includes an outer member having a double-row rolling surface formed on the inner periphery, an inner member having a rolling surface opposed to the rolling surface formed on the outer periphery, A wheel bearing comprising a double row rolling element interposed between opposing rolling surfaces of the member and rotatably supporting the wheel with respect to the vehicle body, wherein the fixed side member of the outer member and the inner member One or more sensor units comprising a strain generating member having two or more contact fixing portions fixed in contact with the sensor, and a sensor attached to the strain generating member and detecting the strain of the strain generating member, The contact fixing portion of the strain generating member is fixed to the fixed side member with a bolt, and friction reducing means for reducing friction between the fixed side member and the knuckle is provided.
According to this configuration, since the contact fixing portion of the strain generating member that is a constituent member of the sensor unit is fixed to the fixed side member with the bolt, the occurrence of slipping between the fixed side member and the sensor unit can be suppressed. Thus, it is possible to avoid distortion in the output signal of the sensor due to slipping. In addition, even if slippage occurs, the friction reduction means for reducing the friction between the fixed side member and the knuckle is provided, so the friction between the fixed side member and the knuckle can be reduced, and the hysteresis generated in the output signal of the sensor. Can be suppressed. As a result, the load applied to the wheel can be accurately detected under any load condition without being affected by hysteresis.

  In this invention, the friction reducing means may be a pasty lubricant applied between the stationary member and a knuckle. When a paste-like lubricant is used, a measure for providing a friction reducing means between the stationary member and the knuckle can be easily performed.

In the present invention, the friction reducing means may be a low friction processing portion that has been subjected to a surface treatment for reducing friction on either one or both of the contact surfaces of the stationary member and the knuckle that contact each other. As the surface treatment, plating or coating can be employed.
If the friction reducing means is provided in advance as a surface treatment, it is not necessary to perform a treatment such as coating when assembling the wheel bearing to the knuckle, and an increase in assembling work can be avoided.

  In the present invention, the friction reducing means may be a self-lubricating plate interposed between the stationary member and a knuckle. As the self-lubricating plate, a sintered body having self-lubricating property, a metal plate subjected to surface treatment having self-lubricating property, a resin plate, or the like can be used. When a self-lubricating plate is interposed, unlike a paste-like lubricant, there is no risk of the surroundings becoming dirty with the lubricant when the wheel bearing is assembled to the knuckle.

  In the present invention, the friction reducing means may be a plate having a low friction surface interposed between the fixed side member and a knuckle. The plate having a low friction surface may be a plate having a low friction coefficient as a whole, or a plate subjected to a surface treatment with low friction. The “low friction” referred to here only needs to have a small coefficient of friction as compared with general metals such as steel that are not subjected to surface treatment.

  In this invention, innumerable parallel fine grooves may be provided on the plate surface having the low friction surface. These innumerable parallel fine grooves are, for example, parallel oblique lines or cross parallel oblique lines. Providing such innumerable parallel fine grooves can also reduce the friction of the plate.

  In the present invention, the sensor unit is preferably arranged such that two or more contact fixing portions of the distortion generating member are located at the same axial position of the fixing side member. In the case of this configuration, the strain in the circumferential direction of the fixed side member can be detected by the sensor unit. That is, since the load acting between the tire and the road surface is transmitted from the rotation side member to the fixed side member via the rolling elements, the outer diameter surface of the fixed side member is distorted in the circumferential direction, and the contact described above. The detection sensitivity is improved by the arrangement of the fixed portion, and the load can be detected with higher accuracy.

  In the present invention, the strain generating member of the sensor unit may be made of a thin plate material having a belt-like schematic shape and a notch portion on a side portion. In the case of this configuration, since the strain of the fixed side member is further enlarged and transmitted to the strain generating member, the load can be detected with higher accuracy.

  In this invention, the strain generating member of the sensor unit is not plastically deformed even in a state where the assumed maximum force is applied as an external force acting on the stationary member or an acting force acting between the tire and the road surface. It is good as a thing. The assumed maximum force may be, for example, a large force exceeding the force generated in the wheel bearing due to the curb ride on the vehicle or the like, but the wheel bearing is not damaged even if the force is applied, This is the maximum force within the range in which the wheel bearing can function normally when the force is released. If plastic deformation occurs before the assumed maximum force is applied, the deformation of the fixed side member is not accurately transmitted to the sensor unit and affects the strain measurement. It is desirable that plastic deformation does not occur even in a state where is applied.

  The sensor-equipped wheel bearing according to the present invention includes an outer member having a double-row rolling surface formed on the inner periphery, an inner member having a rolling surface opposed to the rolling surface formed on the outer periphery, A wheel bearing comprising a double row rolling element interposed between opposing rolling surfaces of the member and rotatably supporting the wheel with respect to the vehicle body, wherein the fixed side member of the outer member and the inner member One or more sensor units comprising a strain generating member having two or more contact fixing portions fixed in contact with the sensor, and a sensor attached to the strain generating member and detecting the strain of the strain generating member, Since the contact fixing portion of the strain generating member is fixed to the fixed side member with a bolt, and friction reducing means for reducing the friction between the fixed side member and the knuckle is provided, it is not affected by hysteresis. Even under load conditions, It is possible to accurately detect the mowing load.

  A first embodiment of the present invention will be described with reference to FIGS. This embodiment is a third generation inner ring rotating type and is applied to a wheel bearing for driving wheel support. In this specification, the side closer to the outer side in the vehicle width direction of the vehicle when attached to the vehicle is referred to as the outboard side, and the side closer to the center of the vehicle is referred to as the inboard side.

  As shown in the sectional view of FIG. 1, the bearing for this sensor-equipped wheel bearing includes an outer member 1 in which a double row rolling surface 3 is formed on the inner periphery, and rolling facing each of these rolling surfaces 3. The inner member 2 has a surface 4 formed on the outer periphery, and the outer member 1 and the double row rolling elements 5 interposed between the rolling surfaces 3 and 4 of the inner member 2. This wheel bearing is a double-row angular ball bearing type, and the rolling elements 5 are made of balls and are held by a cage 6 for each row. The rolling surfaces 3 and 4 have an arc shape in cross section, and are formed so that the ball contact angle is aligned with the back surface. Both ends of the bearing space between the outer member 1 and the inner member 2 are sealed by a pair of seals 7 and 8, respectively.

The outer member 1 is a fixed side member, and has a vehicle body mounting flange 1a attached to a knuckle 16 in a suspension device (not shown) of the vehicle body on the outer periphery, and the whole is an integral part. An outer peripheral surface portion of the outer member 1 closer to the inboard side than the vehicle body mounting flange 1 a is a cylindrical knuckle fitting surface 1 d that fits into the inner peripheral hole of the knuckle 16. The flange 1a is provided with attachment holes 14 with female threads cut at a plurality of locations in the circumferential direction, and knuckle bolts 18 inserted into the bolt insertion holes 17 of the knuckle 16 from the inboard side are attached to the attachment holes 14. The body mounting flange 1a is attached to the knuckle 16 by being screwed together. The mounting hole 14 may be a bolt insertion hole. In that case, the knuckle bolt 18 is fastened and fixed with a nut (not shown).
The inner member 2 is a rotating side member, and includes a hub wheel 9 having a hub flange 9a for wheel mounting, and an inner ring 10 fitted to the outer periphery of the end portion on the inboard side of the shaft portion 9b of the hub wheel 9. And become. The hub wheel 9 and the inner ring 10 are formed with the rolling surfaces 4 of the respective rows. An inner ring fitting surface 12 having a small diameter with a step is provided on the outer periphery of the inboard side end of the hub wheel 9, and the inner ring 10 is fitted to the inner ring fitting surface 12. A through hole 11 is provided at the center of the hub wheel 9. The hub flange 9a is provided with press-fitting holes 15 for hub bolts (not shown) at a plurality of locations in the circumferential direction. In the vicinity of the base portion of the hub flange 9a of the hub wheel 9, a cylindrical pilot portion 13 for guiding a wheel and a braking component (not shown) protrudes toward the outboard side.

  2 is a cross-sectional view taken along the line II-II in FIG. The vehicle body mounting flange 1a of the outer member 1 is a projecting piece 1aa in which a circumferential portion provided with each mounting hole 14 protrudes to the outer diameter side from the other portion.

  Two sets of sensor unit pairs 19 each including two sensor units 20 are provided on the outer diameter surface of the outer member 1 that is a fixed member. The two sensor units 20 constituting the sensor unit pair 19 are arranged at a position that forms a phase difference of 180 degrees in the circumferential direction of the outer diameter surface of the outer member 1. Here, a set of two sensor units 20 is composed of two sensor units 20 arranged on the upper surface portion and the lower surface portion of the outer diameter surface of the outer member 1 that is located above the tire ground contact surface. In addition to the pair 19, another set of sensor units 19 including two sensor units 20 disposed on the right and left surfaces of the outer diameter surface of the outer member 1 that is in the front-rear position with respect to the tire ground contact surface. Provided.

  By providing the two sensor units 20 constituting the sensor unit pair 19 at two locations on the outer diameter surface of the outer member 1 that is located above the tire ground contact surface, the upper surface portion and the lower surface portion. The acting vertical load Fz is detected. Further, the two sensor units 20 constituting the sensor unit pair 19 are provided at two locations on the right surface portion and the left surface portion of the outer diameter surface of the outer member 1 which are front and rear positions with respect to the tire ground contact surface, thereby driving force. The load Fx is detected. As for the sensor unit pair 19 for detecting the vertical load Fz, as shown in FIG. 2, one sensor is provided at the center between two adjacent projecting pieces 1aa on the upper surface portion of the outer diameter surface of the outer member 1. The unit 20 is arranged, and another sensor unit 20 is arranged at the center between the two adjacent protruding pieces 1aa on the lower surface portion of the outer diameter surface of the outer member 1.

  As shown in the enlarged plan view and the enlarged sectional view in FIG. 3A and FIG. 4, these sensor units 20 are attached to the strain generating member 21 and the strain generating member 21 to reduce the strain of the strain generating member 21. It consists of a sensor 22 to detect. The strain generating member 21 is made of an elastically deformable metal such as a steel material and is made of a thin plate material having a thickness of 2 mm or less, and the planar outline is a belt having a constant width over the entire length, and has notches 21b on both sides of the center. The corner of the notch 21b has an arcuate cross section. Further, the strain generating member 21 has two contact fixing portions 21 a that are fixed to the outer diameter surface of the outer member 1 at both ends. Note that, depending on the shape of the strain generating member 21, two or more contact fixing portions 21a may be provided. The sensor 22 is affixed to the strain generating member 21 where the strain increases with respect to the load in each direction. Here, as the location, a central portion sandwiched between the notch portions 21b on both sides is selected on the outer surface side of the strain generating member 21, and the sensor 22 detects a circumferential strain around the notch portion 21b. . Note that the strain generating member 21 is plastically deformed even in a state in which an assumed maximum force is applied as an external force acting on the outer member 1 that is a fixed member or an acting force acting between the tire and the road surface. It is desirable not to do so. This is because when plastic deformation occurs, the deformation of the outer member 1 is not transmitted to the sensor unit 20 and affects the measurement of strain.

  In the sensor unit 20, the two contact fixing portions 21a of the strain generating member 21 are located at the same dimension in the axial direction of the outer member 1, and the two contact fixing portions 21a are separated from each other in the circumferential direction. These contact fixing portions 21a are fixed to the outer diameter surface of the outer member 1 by bolts 23, respectively. Each bolt 23 is inserted into a bolt insertion hole 24 provided in the contact fixing portion 21a in the radial direction and screwed into a screw hole 25 provided in the outer peripheral portion of the outer member 1. In order to stably fix the sensor unit 20 to the outer diameter surface of the outer member 1, the portion where the two contact fixing portions 21a of the strain generating member 21 on the outer diameter surface of the outer member 1 are fixed in contact with each other is flat. Part 1b is formed. In addition, grooves 1c are formed at two intermediate portions on the outer diameter surface of the outer member 1 where the two contact fixing portions 21a of the strain generating member 21 are fixed.

  As described above, by forming the groove 1c at the two intermediate portions where the two contact fixing portions 21a on the outer diameter surface of the outer member 1 are fixed, the strain generating member 21 is formed on the outer diameter surface of the outer member 1. Is fixed with the bolt 23, the central portion having the cutout portion 21b in the thin plate-shaped strain generating member 21 is separated from the outer diameter surface of the outer member 1, and distortion deformation around the cutout portion 21b is easy. It becomes. As the axial position where the contact fixing portion 21a is disposed, an axial position that is the periphery of the rolling surface 3 of the outboard side row of the outer member 1 is selected here. Here, the periphery of the rolling surface 3 of the outboard side row is a range from the intermediate position of the rolling surface 3 of the inboard side row and the outboard side row to the formation portion of the rolling surface 3 of the outboard side row. It is.

  Various sensors 22 can be used. For example, the sensor 22 can be composed of a metal foil strain gauge. In that case, the distortion generating member 21 is usually fixed by adhesion. The sensor 22 can also be formed on the strain generating member 21 with a thick film resistor.

  Friction reducing means for reducing the friction between the outer member 1 and the knuckle 16 that are fixed members is provided. Here, as a specific example of the friction reducing means, between the vehicle body mounting flange 1a of the outer member 1 and the contact surface of the knuckle 16 that contacts the flange 1a (part A shown by double hatching in FIG. 1), and A paste-like lubricant 26 is applied between the outer diameter surface of the outer member 1 and the inner diameter surface of the knuckle 16 fitted to the outer diameter surface (part B shown by hatching in FIG. 1). As the paste lubricant 26, for example, a molybdenum-based paste can be used.

  The sensor 22 of the sensor unit 20 is connected to the estimation means 30. Here, the estimating means 30 is means for estimating the acting force between the wheel tire and the road surface from the output signal of the sensor 22, and includes a signal processing circuit, a correction circuit, and the like. The estimation means 30 has relationship setting means (not shown) in which the relationship between the acting force between the wheel tire and the road surface and the output signal of the sensor 22 is set by an arithmetic expression or a table or the like. The acting force is output from the output signal using the relationship setting means. The setting contents of the relationship setting means are obtained by a test or simulation in advance.

  When a load acts between the tire of the wheel and the road surface, the load is also applied to the outer member 1 that is a stationary member of the wheel bearing, causing deformation. Since the two contact fixing portions 21a of the strain generating member 21 which is a constituent member of the sensor unit 20 are fixed in contact with the outer member 1, the strain of the outer member 1 is transmitted to the strain generating member 21 in an enlarged manner, The distortion is detected by the sensor 22, and the load can be estimated from the output signal.

  In particular, since the contact fixing portion 21a of the strain generating member 21 that is a constituent member of the sensor unit 20 is fixed to the outer member 1 that is a fixed member with the bolts 23, between the outer member 1 and the sensor unit 20. The occurrence of slippage of the sensor 22 can be suppressed, and distortion in the output signal of the sensor 22 accompanying the slippage can be avoided. Further, even if slippage occurs, as a friction reducing means for reducing the friction between the outer member 1 and the knuckle 16, the paste-like lubricant 26 is applied between the outer member 1 and the knuckle 16. Friction between the outer member 1 and the knuckle 16 can be reduced, and hysteresis generated in the output signal of the sensor 22 can be suppressed. As a result, the load applied to the wheel can be accurately detected under any load condition without being affected by hysteresis.

  As another example of the friction reducing means, a process for reducing the friction is performed on one or both of the contact surfaces of the outer member 1 which is the fixed member and the vehicle body mounting flange 1a and the knuckle 16 which are in contact with each other. The low friction processing unit 27 may be provided. The low friction processing portion 27 may be provided only on the contact surface between the vehicle body mounting flange 1a and the knuckle 16, and in addition to the contact surface, the low friction processing portion 27 is in a range extending over the knuckle fitting surface 1d of the outer member 1. Also good. In this case, as a suitable example of the treatment for reducing friction, treatments such as plating and coating can be mentioned.

In the above description, the case where the acting force between the wheel tire and the road surface is detected is shown. However, not only the acting force between the wheel tire and the road surface but also the force acting on the wheel bearing (for example, the preload amount) is detected. It is also good.
By using the detected load obtained from the sensor-equipped wheel bearing for vehicle control of the automobile, it is possible to contribute to stable running of the automobile. In addition, when this sensor-equipped wheel bearing is used, a load sensor can be installed in a compact vehicle, the mass productivity can be improved, and the cost can be reduced.

  Further, in the case of this embodiment, the strain generating member 21 of the sensor unit 20 is made of a thin plate material whose planar outline is a strip having a constant width over the entire length, so that the strain of the outer member 1 is expanded to the strain generating member 21. The distortion is detected by the sensor 22 with high sensitivity, the hysteresis generated in the output signal is reduced, and the load can be estimated with high accuracy. Further, the shape of the strain generating member 21 becomes simple, and the mass productivity is excellent.

  Moreover, in this embodiment, the sensor which makes two sets of the sensor units 20 arrange | positioned in the position which makes the 180 degree phase difference in the circumferential direction on the outer diameter surface of the outer member 1 which is a stationary member. Since two sets of unit pairs 19 are provided, the load can be accurately estimated under any load condition. That is, when a load in a certain direction increases, a portion where the rolling element 5 and the rolling surface 3 are in contact with each other and a portion which is not in contact appear with a phase difference of 180 degrees. If installed with a phase difference, the load applied to the outer member 1 is always transmitted to one of the sensor units 20 via the rolling elements 5, and the load can be detected by the sensor 22.

  5 to 7 show another embodiment of the present invention. In the sensor-equipped wheel bearing, in the embodiment shown in FIGS. 1 to 4, a self-lubricating plate 31 is provided between the vehicle body mounting flange 1 a of the outer member 1 and the knuckle 16 as the friction reducing means. Intervene. Specifically, as shown in FIG. 6, the plate 31 is a ring-shaped plate that overlaps the vehicle body mounting flange 1 a of the outer member 1, and is formed in the projecting piece 1 aa and the mounting hole 14 of the vehicle body mounting flange 1 a. It has a projecting piece 31a and a bolt insertion hole 32 to be aligned.

As the self-lubricating plate 31 in this case, for example, a plate made of a self-lubricating sintered body manufactured by powder metallurgy may be used. As another example, a plate having a surface treatment such as plating having self-lubricating property on the surface of a plate material made of steel or the like may be used. Furthermore, as another example, a low friction plate in which the surface of a plate material made of steel or the like is coated with a fluororesin or a low friction plate made of a fluororesin molded body may be used.
In the case of a low friction plate, an infinite number of parallel fine grooves 31b may be formed on the surface as shown in FIG. FIG. 7A shows an example of a double hatched shape in which inclined line-shaped fine grooves 31b intersect, and FIG. 7B shows an example of a double hatched shape in which vertical and horizontal line-shaped fine grooves 31b intersect. ) Shows an example of a single hatched shape composed of only the fine groove 31b which is a diagonal line in one direction.

It is a figure showing combining the sectional view of the wheel bearing with a sensor concerning one embodiment of this invention, and the block diagram of the conceptual composition of the detection system. II-II arrow sectional drawing in FIG. 1 is shown. (A) is an enlarged plan view which shows the attachment state of the sensor unit in the bearing for wheels with a sensor, (B) is an enlarged plan view of the sensor unit. It is IV-IV arrow directional cross-sectional view in FIG. 3 (A). It is sectional drawing of the bearing for wheels with a sensor concerning other embodiment of this invention. It is a top view of the self-lubricating plate in the wheel bearing with a sensor. It is a top view which shows each example of the fine groove | channel given to the same self-lubricating plate. It is explanatory drawing of the hysteresis in the output signal in a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Outer member 1a ... Body mounting flange 2 ... Inner members 3, 4 ... Rolling surface 5 ... Rolling body 16 ... Knuckle 20 ... Sensor unit 21 ... Strain generating member 21a ... Contact fixing | fixed part 21b ... Notch part 22 ... Sensor 23 ... Bolt 26 ... Paste lubricant (friction reduction means)
27. Low friction processing section (friction reducing means)
31 ... Self-lubricating plate (friction reducing means)
31b ... Fine groove

Claims (9)

An outer member having a double row rolling surface formed on the inner periphery, an inner member having a rolling surface facing the rolling surface formed on the outer periphery, and interposed between the opposing rolling surfaces of both members A double row rolling element, and a wheel bearing for rotatably supporting the wheel with respect to the vehicle body,
The strain generating member having two or more contact fixing portions fixed in contact with the fixed side member of the outer member and the inner member, and the strain generating member attached to the strain generating member One or more sensor units each including a sensor to be detected are provided, and a friction reducing means for reducing the friction between the fixed side member and the knuckle by fixing the contact fixing portion of the strain generating member to the fixed side member with a bolt. A wheel bearing characterized by being provided.   2. The wheel bearing according to claim 1, wherein the friction reducing means is a pasty lubricant applied between the fixed side member and a knuckle.   2. The wheel bearing according to claim 1, wherein the friction reducing unit is a low-friction processing unit that is subjected to a surface treatment that reduces low friction on one or both of the contact surfaces of the stationary member and the knuckle that contact each other.   2. The wheel bearing according to claim 1, wherein the friction reducing means is a self-lubricating plate interposed between the stationary member and a knuckle.   2. The wheel bearing according to claim 1, wherein the friction reducing means is a plate having a low friction surface interposed between the stationary member and a knuckle.   6. The wheel bearing according to claim 5, wherein the plate surface having the low friction surface is provided with innumerable parallel fine grooves.   The sensor unit according to any one of claims 1 to 6, wherein the sensor unit is arranged such that two or more contact fixing portions of the distortion generating member are positioned in the same axial direction of the fixing side member. Wheel bearing.   8. The sensor-equipped wheel bearing according to claim 1, wherein the strain generating member of the sensor unit is made of a thin plate material having a belt-like shape in a plan view and a notch portion on a side portion.   9. The strain generating member of the sensor unit according to claim 1, wherein the strain generating member is an assumed maximum force as an external force acting on the stationary member or an acting force acting between a tire and a road surface. A wheel bearing with a sensor, which is not plastically deformed even in a state where a voltage is applied.

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