JP2008191126A - Wheel bearing with sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wheel bearing with a sensor enabling to compactly install the sensor for detecting a load in a vehicle, without worsening the rigidity of the bearing, capable of detecting sensitively the load applied onto the vehicle, excellent in mass productivity, and enabling cost reduction. <P>SOLUTION: This wheel bearing interposed with a plurality of trains of rotors 5 between a fixed wheel 1 and a rotary wheel 2 is provided with the ultrasonic sensor 21 having at least one transmission part 22 and reception part 23 in the fixed wheel 1. The ultrasonic sensor 21 receives an ultrasonic wave transmitted from the transmission part 22 directly, or an echo reflected on a reflecting face 1aa provided on the fixed wheel 1, by the reception part 23. The wheel bearing is provided with an estimation means 31 for estimating an acting force between a tire and a road face, or a pre-load of the wheel bearing, based on a level of the ultrasonic wave detected by the reception part 23, or an arrival time until receiving the ultrasonic wave by the reception part 23 after transmitting the ultrasonic wave by the transmission part 22. <P>COPYRIGHT: (C)2008,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.

  2. Description of the Related Art Conventionally, there is a wheel bearing provided with a sensor for detecting the rotational speed of each wheel for safe driving of an automobile. Conventional measures to ensure driving safety of general automobiles are performed by detecting the rotational speed of the wheels of each part, but the rotational speed of the wheels is not sufficient, and it is further safer by using other sensor signals. It is required that the surface can be controlled.

  Therefore, it is conceivable to control the posture from the load acting on each wheel during vehicle travel. For example, a large load is applied to the outer wheel in cornering, and the load applied to each wheel is not uniform. In addition, even when the load is uneven, the load applied to each wheel is uneven. For this reason, if the load applied to the wheel can be detected at any time, the suspension control etc. is controlled in advance based on the detection result, thereby controlling the attitude during vehicle travel (preventing rolling during cornering, preventing the front wheel from sinking during braking, It is possible to prevent subsidence due to uneven load capacity.

  In addition, when steer-by-wire is introduced in the future and the system becomes a system in which the axle and the steering are not mechanically coupled, it is required to detect the axle direction load and transmit the road surface information to the handle held by the driver.

As a response to such a demand, a wheel bearing has been proposed in which an ultrasonic sensor is provided on the outer ring of the wheel bearing and the load is detected from an echo ratio that varies depending on the contact area between the rolling element and the rolling surface (for example, Patent Documents 1 and 2). 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 Documents 3 and 4).
JP 2006-177932 A JP 2006-292027 A Special table 2003-530565 gazette JP 2003-336653 A

However, the techniques disclosed in Patent Documents 1 and 2 have the following problems.
-Since ultrasonic waves are repeatedly reflected and propagated in a complicated manner, it affects other ultrasonic sensors installed at other positions, and it is difficult to accurately detect the load.
-Since it is necessary to install an ultrasonic sensor so that an ultrasonic wave is emitted toward the contact surface between the rolling element and the rolling surface, it is difficult to position the ultrasonic sensor.
・ If the number of installed ultrasonic sensors is small, the load can be measured only when passing through the rolling element. To measure the static load, install multiple ultrasonic sensors or use a wide range of transmitters and receivers. It is necessary to use a sonic sensor.

In addition, the techniques disclosed in Patent Documents 3 and 4 have the following problems.
-It is difficult to detect the load in the vertical direction among the loads in the triaxial directions perpendicular to each other that act on the contact point between the tire and the road surface because the deformation amount of the fixed wheel is small.
In addition, although it is conceivable to measure the deformation of the fixed ring using an optical displacement sensor, the optical displacement sensor has a problem that it is vulnerable to vibration and dirt.

  The object of the present invention is to provide a sensor for detecting a load on a vehicle in a compact manner without reducing the rigidity of the bearing, to detect the load applied to the wheel with high sensitivity, to achieve excellent mass productivity, and to reduce the cost. It is to provide a bearing for an automobile.

The sensor-equipped wheel bearing according to the present invention includes a stationary wheel having a double-row rolling surface formed on a circumferential surface, a rotating wheel having a rolling surface facing the rolling surface of the fixed wheel, and a facing rolling wheel. In a wheel bearing having a double row rolling element interposed between running surfaces and rotatably supporting the wheel with respect to the vehicle body, an ultrasonic sensor having at least one transmitter and receiver is provided on the fixed wheel. The ultrasonic sensor is configured such that the ultrasonic wave transmitted from the transmission unit is received directly or by the reception unit that receives the echo reflected by the reflecting surface provided on the fixed ring, and the ultrasonic sensor detected by the reception unit of the ultrasonic sensor. Estimating means for estimating the acting force between the tire and the road surface or the preload amount of the wheel bearing from the magnitude of the sound wave is provided.
Another sensor-equipped wheel bearing according to the present invention is the above-described sensor-equipped wheel bearing according to the present invention, wherein as the estimating means, the acting force between the tire and the road surface from the magnitude of the ultrasonic wave detected by the receiving unit, Alternatively, instead of estimating the preload amount of the wheel bearing, the acting force between the tire and the road surface from the arrival time from when the transmitting unit transmits the ultrasonic wave until the receiving unit receives the ultrasonic wave, or The preload amount of the wheel bearing is estimated. The arrival time is a time from transmission from the transmission unit to reception by the reception unit, and includes a phase difference between signals of the transmission unit and the reception unit caused by arrival time.

When a load is applied to the rotating wheels as the vehicle travels, the fixed wheels are deformed via the rolling elements. The ultrasonic sensor provided on the fixed ring transmits ultrasonic waves from the transmission unit, and receives them by the reception unit. The ultrasonic waves detected by the receiving unit when the relative positional relationship between the transmitting unit and the receiving unit changes due to deformation of the fixed ring due to the load, or the relative positional relationship between the transmitting unit, the receiving unit, and the reflecting surface changes. And the arrival time from when the transmission unit transmits the ultrasonic wave until the reception unit receives the ultrasonic wave changes, the load can be estimated from the size or the arrival time. The estimating means estimates the acting force between the tire and the road surface or the preload amount of the wheel bearing from the magnitude or arrival time of the ultrasonic wave detected by the receiving unit. By using the acting force between the tire and the road surface thus obtained or the preload amount of the wheel bearing for vehicle control of the automobile, fine vehicle control is possible.
In the case of an ultrasonic sensor, the degree of freedom in design is high because a certain distance may be provided between the transmitter and the receiver. Since the ultrasonic sensor can be installed simply by subjecting the wheel bearing to simple processing, the ultrasonic sensor can be installed compactly in the vehicle without lowering the rigidity of the bearing, resulting in excellent mass productivity and cost reduction. The ultrasonic sensor is also resistant to vibration. Furthermore, since the ultrasonic wave has good directivity, the magnitude and arrival time of the ultrasonic wave detected by the receiving unit are likely to change even with a slight relative displacement, and a highly sensitive measurement result can be obtained.

The ultrasonic sensor may be configured such that the ultrasonic wave transmitted from the transmission unit propagates in the air and reaches the reception unit.
Since ultrasonic waves are easily attenuated in the air, even if a plurality of sensors are installed, they hardly affect each other. For this reason, it is possible to improve the detection accuracy by installing a plurality of sensors.

The ultrasonic sensor may be configured such that the ultrasonic wave transmitted from the transmission unit is reflected by a reflecting plate provided on the fixed ring and travels toward the reception unit.
If it is set as the said structure, the transmission part and receiving part of an ultrasonic sensor can be made into a different body, and the freedom degree of design increases. In addition, since the transmission unit and the reception unit can be arranged at locations where the relative displacement amount is large, the deformation of the fixed ring can be measured with high sensitivity.

The ultrasonic sensors may be provided at four locations in the circumferential direction of the fixed ring.
When ultrasonic sensors are provided at four locations in the circumferential direction of the fixed wheel, the magnitudes of loads in various directions such as triaxial loads acting on the tire and road contact point are calculated by calculating the respective signals. Is more easily estimated.

  The sensor-equipped wheel bearing according to the present invention includes a stationary wheel having a double-row rolling surface formed on a circumferential surface, a rotating wheel having a rolling surface facing the rolling surface of the fixed wheel, and a facing rolling wheel. In a wheel bearing having a double row rolling element interposed between running surfaces and rotatably supporting the wheel with respect to the vehicle body, an ultrasonic sensor having at least one transmitter and receiver is provided on the fixed wheel. The ultrasonic sensor is configured such that the ultrasonic wave transmitted from the transmission unit is received directly or by the reception unit that receives the echo reflected by the reflecting surface provided on the fixed ring, and the ultrasonic sensor detected by the reception unit of the ultrasonic sensor. The acting force between the tire and the road surface or the preload amount of the wheel bearing is estimated from the size of the sound wave or the arrival time from when the transmitting unit transmits the ultrasonic wave until the receiving unit receives the ultrasonic wave. Since the estimation means is provided, it is fixed by the ultrasonic sensor. Measuring the deformation of the wheel, it is possible to the load applied to the wheel than the amount of deformation sensitively detected, it is possible to use the detected load to a vehicle control of the vehicle. Since the ultrasonic sensor can be installed simply by subjecting the wheel bearing to simple processing, the ultrasonic sensor can be installed compactly in the vehicle without lowering the rigidity of the bearing, resulting in excellent mass productivity and cost reduction.

  A first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a cross-sectional view of a sensor-equipped wheel bearing and a block diagram of a conceptual configuration of a detection system thereof, and FIG. 2 is a front view of an outer member of the sensor-equipped wheel bearing. The cross-sectional view of FIG. 1 shows a cross section taken along the line I-O-I 'in FIG. 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. In FIG. 1, the left side is the outboard side and the right side is the inboard side.

  This sensor-equipped wheel bearing includes an outer member 1 having a double row rolling surface 3 formed on the inner periphery, an inner member 2 having a rolling surface 4 opposed to each of the rolling surfaces 3, and these It is comprised with the rolling element 5 of the double row interposed between the rolling surfaces 3 and 4 of the outer member 1 and the inner member 2. FIG. 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 a circular arc 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 sealing devices 7 and 8, respectively.

The outer member 1 is a fixed wheel, and has a vehicle body attachment flange 1a attached to a knuckle in a suspension device (not shown) of the vehicle body on the outer periphery, and is formed as an integral part as a whole. The flange 1a is provided with a vehicle body mounting hole 14 having a female thread portion formed on the inner periphery at a plurality of locations in the circumferential direction.
The inner member 2 serves as a rotating wheel, 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 inboard side end of the shaft portion 9b of the hub wheel 9; It becomes. 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 brake component (not shown) protrudes toward the outboard side.

  A sensor mounting base 20 is fixed with a screw or the like on the outer peripheral surface of the outer member 1 at a location on the outboard side of the vehicle body mounting flange 1a, and an ultrasonic wave for load detection is applied to the surface of the sensor mounting base 20 on the inboard side. A sensor 21 is attached. The ultrasonic sensor 21 includes a transmission unit 22 and a reception unit 23, and an ultrasonic wave emitted from the transmission unit 22 is reflected by the outboard side surface 1aa of the vehicle body mounting flange 1a, which is a reflection surface, and an echo of the reflected ultrasonic wave. Is received by the receiving unit 23. When the ultrasonic sensor 21 is provided at one place, the installation place in the circumferential direction is not particularly limited.

  As shown in FIG. 1, as means for processing the output of the ultrasonic sensor 21, an estimation means 31 for estimating the acting force between the tire and the road surface or the preload amount of the wheel bearing from the output of the ultrasonic sensor 21, and this An abnormality determining unit 32 is provided for outputting an abnormal signal to the outside from the estimation result of the estimating unit 31. These means 31 and 32 may be provided in an electronic circuit device (not shown) on a circuit board or the like attached to the outer member 1 of the wheel bearing, or may be an electric control unit ( ECU).

  The operation of the sensor-equipped wheel bearing with the above configuration will be described. When a load is applied to the hub wheel 9, the outer member 1 is deformed via the rolling elements 5. The ultrasonic sensor 21 provided on the outer member 1 transmits ultrasonic waves from the transmission unit 22, and the reception unit 23 detects ultrasonic echoes reflected by the outboard side surface 1 aa of the vehicle body mounting flange 1 a. Due to the deformation of the outer member 1 due to the load, the relative positional relationship between the transmitting portion 22 and the receiving portion 23 of the ultrasonic sensor 21 and the reflecting surface 1aa of the vehicle body mounting flange 1a changes, so that the ultrasonic waves detected by the receiving portion 23 are detected. The load time can be estimated from the magnitude or the arrival time since the arrival time from the transmission unit 22 transmitting the ultrasonic wave to the reception unit 23 receiving the echo changes. The arrival time can be obtained from the phase difference from the ultrasonic wave transmitted from the transmitting unit 22 and received by the receiving unit 23.

  Since the change in the relative positional relationship varies depending on the direction and magnitude of the load, if the relationship between the relative positional relationship and the load is obtained in advance through experiments and simulations, the acting force between the tire and the road surface or the preload of the wheel bearing The amount can be estimated. The estimation means 31 estimates the acting force between the tire and the road surface or the preload amount of the wheel bearing from the magnitude or arrival time of the ultrasonic wave detected by the receiving unit 23. That is, the estimating means 31 is a calculation formula in which a relationship between the magnitude or arrival time of the ultrasonic wave detected by the receiving unit 23 and the acting force between the tire and the road surface or the preload amount of the wheel bearing is set. It has relation setting means (not shown) such as a table, and the estimation is performed by collating the detection signal with the relation setting means. Further, the abnormality determining means 32 is externally provided when it is determined that the acting force between the tire and the road surface estimated by the estimating means 31 or the preload amount of the wheel bearing exceeds an arbitrarily set allowable value. An abnormal signal is output. This abnormal signal can be used for vehicle control of an automobile. If the action force between the tire and the road surface or the preload amount of the wheel bearing is output in real time, finer vehicle control becomes possible.

  In the case of the ultrasonic sensor 21, a certain degree of distance may be provided between the transmission unit 22 and the detection surface, and between the detection surface and the reception unit 23, so that the degree of freedom in design is high. Since the ultrasonic sensor 21 can be installed by simply processing the wheel bearing by using the sensor mounting base 20, it can be installed compactly in the vehicle without lowering the rigidity of the bearing, and has excellent mass productivity. The cost can be reduced. Further, the ultrasonic sensor 21 is resistant to vibration. Furthermore, since the ultrasonic waves have good directivity, even the slight deformation of the outer member 1 tends to change the size and arrival time of the ultrasonic waves detected by the receiving unit 23, and a highly sensitive measurement result can be obtained. Furthermore, as in this embodiment, when the ultrasonic wave propagates in the air, the ultrasonic wave is easily attenuated in the air and has a wide range of propagation. Therefore, it is possible to improve detection accuracy by installing a plurality of sensors.

FIG. 3 shows a second embodiment of the present invention. The ultrasonic sensor 21 of the first embodiment has the transmission unit 22 and the reception unit 23 arranged at the same place, whereas the ultrasonic sensor 21 of the second embodiment includes the transmission unit 22 and the reception unit. The parts 23 are arranged at different locations on the outer member 1. Specifically, the transmitter 22 is attached to a mounting base 20 fixed to the outer peripheral surface of the outer member 1, and the receiver 23 is attached to the vehicle body mounting flange 1 a of the outer member 1, and is transmitted from the transmitter 22. The receiving unit 23 directly receives the ultrasonic waves. The transmitter 22 and the receiver 23 may be attached in reverse. The other configuration is the same as that of the first embodiment, and the same components are denoted by the same reference numerals.
In the case of this embodiment, the ultrasonic wave detected by the receiving unit 23 is changed by changing the relative positional relationship between the transmitting unit 22 and the receiving unit 23 of the ultrasonic sensor 21 due to the deformation of the outer member 1 due to the load. And the arrival time from when the transmission unit 22 transmits ultrasonic waves to when the reception unit 23 receives an echo changes. Therefore, the load can be estimated from the size or the arrival time.
By disposing the transmitter 22 and the receiver 23 at different locations, the locations where the transmitter 22 and the receiver 23 are attached to the outer member 1, that is, the outer peripheral surface of the outer member 1 and the vehicle body mounting flange 1a are The degree of deformation can be different from each other, and the deformation of the outer member 1 can be measured with high sensitivity. Moreover, if the transmission unit 22 and the reception unit 23 are arranged at different locations, the degree of freedom in design is further increased.

FIG. 4 shows a third embodiment of the present invention. In this embodiment as well, the transmitter 22 and the receiver 23 of the ultrasonic sensor 21 are arranged at different locations on the outer member 1, but unlike the second embodiment, an ultrasonic wave transmitted from the transmitter 22 is used. The ultrasonic sensor 21 is configured such that the sound wave is reflected by the reflecting plate 24 provided on the outer member 1 and travels toward the receiving unit 23. Specifically, the transmitter 22 is directly attached to the outer peripheral surface of the outer member 1 with an adhesive or the like, and an ultrasonic wave transmitted from the transmitter 22 in the outer diameter direction is screwed to the outer end surface of the vehicle body mounting flange 1a. The light is reflected at a right angle in the axial direction by the reflector 24 attached in the manner described above and received by the receiver 23 arranged on the vehicle body attachment flange 1a of the outer member 1. In this example, the receiving portion 23 is attached to the receiving portion attaching portion 24a formed on a part of the reflector 24. However, the receiving portion 23 may be attached directly to the vehicle body attaching flange 1a. Moreover, you may attach the transmission part 22 and the receiving part 23 reversely. Other configurations are the same as those in the first and second embodiments, and the same reference numerals are given to the same components.
Thus, also when it is set as the structure which reflects the ultrasonic wave transmitted from the transmission part 22 with the reflecting plate 24, and receives with the receiving part 23, the effect similar to the said 2nd Embodiment is acquired. Whether the ultrasonic wave transmitted from the transmission unit 22 is directly received by the reception unit 23 or reflected by the reflection plate 24 and received by the reception unit 23 depends on the shape and arrangement of the wheel bearing and its peripheral devices. Just choose.

In each of the above embodiments, the ultrasonic sensor 21 is provided only at one place in the circumferential direction of the outer member 1. However, as shown in FIGS. 5 and 6, the ultrasonic sensor 21 is provided at four places in the circumferential direction. More preferably. FIG. 5 shows a transmitter 22 (or receiver 23) attached to the outer peripheral surface of the outer member 1 via a mounting base 20A, and a receiver attached to the vehicle body mounting flange 1a of the outer member 1 via a mounting base 20B. An ultrasonic wave is transmitted to and received from the unit 23 (or the transmission unit 22). Further, FIG. 6 shows a transmitter 22 (or a receiver 23) attached to the outer peripheral surface of the outer member 1 via the mounting base 20A, and a different portion of the outer peripheral surface of the outer member 1 via the mounting base 20B. An ultrasonic wave is transmitted / received to / from the attached receiver 23 (or transmitter 22).
5 and 6, both the transmission unit 22 and the reception unit 23 are arranged on a plane perpendicular to the axial direction. However, as in the second and third embodiments, the transmission unit 22 and the reception unit 23 are arranged in the axial direction. May be arranged at different positions. Further, as in the first embodiment, the transmission unit 22 and the reception unit 23 are arranged at the same place, and the ultrasonic waves transmitted from the transmission unit 22 are reflected by the reflection surface provided on the outer member 1 and received. You may make it make the part 23 receive.
If the ultrasonic sensors 21 are provided at four locations in the circumferential direction, the direction of the load can be easily estimated by comparing the outputs of the ultrasonic sensors 21. For example, it is possible to estimate the magnitudes of loads in various directions such as loads Fz, Fx, and Fy in three axial directions that are perpendicular to each other and act on the contact point between the tire and the road surface. The three-axis direction refers to a Z-axis direction that is a vertical direction, an X-axis direction that is a vehicle front-rear direction, and a Y-axis direction that is a vehicle width direction (see FIG. 1). Since the magnitude of the load in various directions can be estimated, the load Fz in the vertical direction, which has been difficult to detect with a load using a conventional strain sensor, can be accurately detected.

In each of the embodiments described above, the case where the outer member 1 is a fixed ring has been described. However, the present invention can also be applied to a wheel bearing in which the inner member is a fixed ring. In that case, the ultrasonic sensor is installed on the inner member, and the deformation of the inner member is measured.
In each of the above embodiments, the case where the present invention is applied to a third generation type wheel bearing has been described. However, the present invention is for a first or second generation type wheel in which the bearing portion and the hub are independent parts. The present invention can also be applied to a bearing or a fourth-generation type wheel bearing in which a part of the inner member is composed of an outer ring of a constant velocity joint. Further, this sensor-equipped wheel bearing can be applied to a wheel bearing for a driven wheel, and can also be applied to a tapered roller type wheel bearing of each generation type.

It is a figure showing combining the sectional view of the bearing for wheels with a sensor concerning a 1st embodiment of this invention, and the block diagram of the conceptual composition of the detection system. It is a front view, such as an outward member of the wheel bearing with a sensor. It is a figure showing combining the sectional view of the bearing for wheels with a sensor concerning a 2nd embodiment of this invention, and the block diagram of the conceptual composition of the detection system. It is a figure which combines and shows the sectional view of the wheel bearing with a sensor concerning the 3rd Embodiment of this invention, and the block diagram of the conceptual structure of the detection system. It is a front view, such as an outward member which shows arrangement | positioning of a different ultrasonic sensor. Furthermore, it is a front view, such as an outward member which shows arrangement | positioning of a different ultrasonic sensor.

Explanation of symbols

1. Outer member (fixed ring)
DESCRIPTION OF SYMBOLS 1a ... Car body mounting flange 1aa ... Reflecting surface 2 ... Inward member (rotating wheel)
3, 4 ... rolling surface 5 ... rolling element 20 ... mount 21 ... ultrasonic sensor 22 ... transmitter 23 ... receiver 24 ... reflector

Claims (5)

A fixed ring with a double-row rolling surface formed on the peripheral surface, a rotating wheel that forms a rolling surface opposite to the rolling surface of the fixed ring, and a double-row rolling surface interposed between the opposing rolling surfaces. In a wheel bearing comprising a moving body and rotatably supporting the wheel with respect to the vehicle body,
An ultrasonic sensor having at least one transmission unit and a reception unit is provided on the fixed ring, and the ultrasonic sensor transmits an echo reflected from the ultrasonic wave transmitted from the transmission unit directly or on a reflection surface provided on the fixed ring. The receiving unit is configured to receive, and provided with an estimation means for estimating the acting force between the tire and the road surface or the preload amount of the wheel bearing from the magnitude of the ultrasonic wave detected by the receiving unit of the ultrasonic sensor. Bearing with sensor wheel. A fixed ring with a double-row rolling surface formed on the peripheral surface, a rotating wheel that forms a rolling surface opposite to the rolling surface of the fixed ring, and a double-row rolling surface interposed between the opposing rolling surfaces. In a wheel bearing comprising a moving body and rotatably supporting the wheel with respect to the vehicle body,
An ultrasonic sensor having at least one transmission unit and a reception unit is provided on the fixed ring, and the ultrasonic sensor transmits an echo reflected from the ultrasonic wave transmitted from the transmission unit directly or on a reflection surface provided on the fixed ring. The receiving unit is configured to receive, the acting force between the tire and the road surface, or the wheel bearing from the arrival time from when the transmitting unit of the ultrasonic sensor transmits the ultrasonic wave until the receiving unit receives the ultrasonic wave A bearing for a wheel with a sensor, characterized in that an estimation means for estimating the amount of preload is provided.   3. The sensor-equipped wheel bearing according to claim 1, wherein the ultrasonic sensor is configured such that an ultrasonic wave transmitted from a transmitting unit propagates in the air and reaches the receiving unit.   4. The sensor-equipped wheel bearing according to claim 3, wherein the ultrasonic sensor is configured such that an ultrasonic wave transmitted from a transmission unit is reflected by a reflecting plate provided on the fixed wheel and travels toward a reception unit.   5. The sensor-equipped wheel bearing according to claim 1, wherein the ultrasonic sensors are provided at four locations in the circumferential direction of the fixed wheel. 6.

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