JP2010127376A - Sensor equipped bearing for wheel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sensor equipped bearing for a wheel capable of accurately detecting loads acting on the bearing and on the ground contact surface of a tire without being affected by rolling bodies. <P>SOLUTION: The bearing for the wheel is formed by arranging rolling bodies 5 between double-row, opposed rolling surfaces of an outer member 1 and an inner member 2. A fixed-side member among the outer member 1 and the inner member 2 is provided with one or more sensor units 20. Each of the sensor units 20 is provided with a distortion generating member 21 having two or more contacting fixed sections which are in contact with and fixed to the fixed-side member, and also with a sensor 22 for detecting the distortion of the distortion generating member. The sensor units 20 are arranged such that each of the deforming members 21 thereof is located at a position so as to be offset from a line L passing through the center of each rolling body 5 and extending in the direction of forming a rolling body contact angle, and on an inboard side further from the rolling body 5 on the inboard side among the double-row rolling bodies. <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 unit including a strain generating member and a strain sensor attached to the strain generating member is attached to a fixed ring of a bearing, and the strain generating member is attached to the fixed wheel. A sensor-equipped wheel bearing has been proposed which has at least two contact fixing portions, and has at least one notch portion between adjacent contact fixing portions, and the strain sensor is disposed in the notch portion. (For example, Patent Document 1).

According to this sensor-equipped wheel bearing, when a load is applied to the rotating wheel as the vehicle travels, the fixed wheel is deformed via the rolling elements, and this deformation causes distortion of the sensor unit. The strain sensor provided in the sensor unit detects the strain of the sensor unit. If the relationship between strain and load is obtained in advance through experiments and simulations, the load applied to the wheel can be detected from the output of the strain sensor.
JP 2007-57299 A

  However, in the sensor-equipped wheel bearing, each time the rolling element passes near the sensor unit installation portion, the fixed wheel is deformed by the rolling element load, and the amplitude of the output signal of the sensor unit increases. That is, the output signal of the sensor unit becomes a periodic waveform affected by the rolling elements, and the load cannot be detected with high accuracy.

  An object of the present invention is to provide a wheel bearing with a sensor that can accurately detect a load acting on a wheel bearing or a tire ground contact surface without being affected by rolling elements.

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 each including 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, A position on the inboard side further than the inboard side rolling element of the double row rolling elements at a position where the strain generating member deviates from a line segment passing through the center of the rolling element and forming a rolling element contact angle. It is characterized by being provided in. The fixed side member is, for example, the outer member. The sensor unit may be plural.
The stationary member is deformed by the load of the rolling element that passes through. In particular, the deformation due to the rolling element load is large on a line segment that extends in the direction that forms the contact angle of the rolling element through the center of the rolling element. That is, it is easily affected by the rolling element load. In this sensor-equipped wheel bearing, the sensor unit is connected to the inner side of the double-row rolling elements of the fixed-side member that deviates from the line extending in the direction in which the strain generating member passes through the center of the rolling element and forms the rolling element contact angle. Since it is provided at a position closer to the inboard side than the rolling element on the board side, the distortion generating member of the sensor unit is less affected by the rolling element load. Therefore, the deformation of the fixed side member due to the original load can be accurately detected by the sensor unit, and the load acting between the tire of the wheel and the road surface can be accurately detected from the output signal.

  In the present invention, at least three or more sensor units are provided, and the radial load acting in the radial direction of the wheel bearing or tire and the axial direction of the wheel bearing or tire from the output signals of the sensors of these sensor units. A load estimation means for estimating the axial load may be provided.

In this invention, you may arrange | position the said sensor unit in the upper surface part of the outer diameter surface of the said fixed side member which becomes a vertical position and a left-right position with respect to a tire ground-contact surface, a lower surface part, a right surface part, and a left surface part.
In this configuration, the vertical load Fz and the axial load Fy can be estimated from the output signals of the two sensor units arranged on the upper surface and the lower surface on the outer diameter surface of the fixed member, and the outer diameter of the fixed member can be estimated. The load Fx caused by the driving force or the braking force can be estimated from the output signals of the two sensor units arranged on the right and left surfaces of the surface.

  In the present invention, the strain generating member of the sensor unit may be made of a thin plate material having a belt-like general shape. Moreover, it is good also as what has a notch part in the side part of the distortion generating member. In the case of this configuration, the distortion of the fixed side member is easily transmitted to the distortion generating member, the distortion is detected with high sensitivity by the sensor, 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 can be simplified, and it can be made compact and inexpensive.

  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 is, for example, the maximum force within a range in which a normal function as a bearing excluding the sensor system is restored even if an excessive load is applied to the bearing. 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.

In this invention, you may provide the correction | amendment means which correct | amends the output signal of the sensor of the said sensor unit in the front | former stage of the said load estimation means.
As described above, by devising the installation position of the sensor unit, the output signal of the sensor unit can reduce the influence of the rolling elements that pass through, but the influence still remains. The output signal of the sensor unit in this case has a waveform whose amplitude changes with the arrangement pitch of the rolling elements as a period. Therefore, for example, a rolling element detection unit that detects the rotational position of the rolling element is provided separately, and the correction unit increases or decreases the amplitude of the output signal of the sensor unit according to the rolling element position detected by the rolling element detection unit. If it is assumed, the influence of the position of the rolling element can be eliminated.
In addition, if the temperature of the wheel bearing changes due to heat generated by the rotation of the bearing or the surrounding environment, the sensor output signal of the sensor unit fluctuates due to thermal expansion, etc., even if the load does not change. The effect remains. Therefore, by providing temperature correction means for correcting the sensor output signal of the sensor unit according to the temperature of the wheel bearing or its surrounding temperature, detection errors due to temperature can be reduced.

In the present invention, an axial load direction determining means for determining the direction of the axial load may be further provided.
When estimating the axial load from the sensor output signal of the sensor unit, the direction may not be determined. Thus, if an axial load direction discriminating means for discriminating the direction of the axial load is provided separately from the sensor unit, the axial load can be accurately estimated.

  In this invention, the fixed side member has a flange on the peripheral surface thereof, and the axial load direction determining means is an L-shaped strain generating member provided across the peripheral surface of the fixed side member and the flange. And a direction discrimination sensor having a sensor attached to the strain generating member and detecting the strain of the strain generating member.

  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 each including 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, A position on the inboard side further than the inboard side rolling element of the double row rolling elements at a position where the strain generating member deviates from a line segment passing through the center of the rolling element and forming a rolling element contact angle. Without being affected by rolling elements The load acting on the wheel support bearing and the tire contact surface can be accurately detected.

  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 (not shown) in the suspension device of the vehicle body on the outer periphery, and the whole is an integral part. The flange 1a is provided with screw holes 14 for mounting the vehicle body at a plurality of locations in the circumferential direction, and knuckle bolts (not shown) inserted into the bolt insertion holes of the knuckle from the inboard side are screwed into the screw holes 14. Thus, the vehicle body mounting flange 1a is attached to the knuckle.
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-fit holes 16 for hub bolts 15 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.

  FIG. 2 shows a front view of the outer member 1 of the wheel bearing as viewed from the outboard side. 1 shows a cross-sectional view taken along the line 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 screw hole 14 protrudes to the outer diameter side from the other portion. As shown in the figure, two sensor unit pairs 19A and 19B, each having two sensor units 20 as one set, are provided on the outer diameter surface of the outer member 1 which is a fixed member. The two sensor units 20 of each pair of sensor units 19 </ b> A and 19 </ b> B 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, the two sensor units 20 constituting one set of sensor unit pair 19A are provided at two locations on the upper surface portion and the lower surface portion of the outer diameter surface of the outer member 1 that are in the vertical position with respect to the tire ground contact surface. ing. Further, two sensor units 20 constituting another pair of sensor units 19B 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. It has been.

  The two sensor units 20 constituting the sensor unit pair 19 </ b> A are provided at two locations on the outer diameter surface of the outer member 1 that is in the vertical position with respect to the tire ground contact surface, so that the wheel bearing is provided. The acting vertical load Fz is detected. Further, the two sensor units 20 constituting the sensor unit pair 19B 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. And a load Fx as a braking force is detected. For the sensor unit pair 19A for detecting the vertical load Fz, one sensor unit 20 is disposed at the center between the two adjacent projecting pieces 1aa on the upper surface portion of the outer diameter surface of the outer member 1. Another sensor unit 20 is arranged at the center between the two adjacent projecting pieces 1aa on the lower surface portion of the outer diameter surface of the outer member 1.

  3 and 4, the sensor unit 20 includes a strain generating member 21 and a strain that is attached to the strain generating member 21 and detects the strain of the strain generating member 21. The sensor 22 is used. 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. 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 strain sensor 22 is affixed to a location where the strain increases with respect to the load in each direction on the strain generating member 21. Here, as the location, the 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 strain sensor 22 detects the strain in the circumferential direction around the notch portion 21b. To do. 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. The assumed maximum force is, for example, the maximum force within a range in which a normal function as a bearing excluding the sensor system is restored even if an excessive load is applied to the bearing.

  As shown in FIG. 1, the sensor unit 20 has a plurality of strain generating members 21 at positions deviating from a line segment L indicated by a one-dot chain line extending in a direction passing through the center of the rolling element 5 and forming a rolling element contact angle. It is provided at a position on the inboard side further than the rolling body 5 on the inboard side among the rolling elements 5 in the row. Specifically, the sensor unit 20 is provided on the outer diameter surface of the outer member 1 on the inboard side of the vehicle body mounting flange 1a.

  Further, as shown in FIG. 4, the sensor unit 20 has a position where the two contact fixing portions 21 a of the strain generating member 21 are in the same dimension in the axial direction of the outer member 1 and 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 24 through spacers 23, respectively. Thereby, the strain sensor 22 of the sensor unit 20 detects the strain in the outer member circumferential direction around the notch 21 b of the strain generating member 21. Each bolt 24 is inserted into a bolt insertion hole 26 of the spacer 23 from a bolt insertion hole 25 penetrating in the radial direction provided in the contact fixing portion 21 a, and a screw hole 27 provided in the outer peripheral portion of the outer member 1. Screwed on. In this way, by fixing the contact fixing portion 21a to the outer diameter surface of the outer member 1 via the spacer 23, the central portion having the notch portion 21b in the strain generating member 21 having a thin plate shape is the outer member 1. It becomes a state away from the outer diameter surface of the, and distortion deformation around the notch 21b becomes easy. 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.

  Various strain sensors 22 can be used. For example, the strain 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 strain sensor 22 can also be formed on the strain generating member 21 with a thick film resistor.

  The strain sensor 22 of the sensor unit 20 is connected to the load estimation means 30. Here, the load estimating means 30 is a means for estimating the acting force between the tire of the wheel and the road surface based on the output signal of the strain sensor 22, and includes a signal processing circuit and a correction circuit. The load estimating means 30 has relation setting means (not shown) in which the relation between the acting force between the tire of the wheel and the road surface and the output signal of the distortion sensor 22 is set by an arithmetic expression or a table, etc. The acting force is output from the output signal of the sensor 22 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 strain is detected by the strain sensor 22, and the load can be estimated from the output signal.

  Further, since the contact fixing portion 21 a 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 bolt 24, between the outer member 1 and the sensor unit 20. Thus, it is possible to prevent the output signal of the strain sensor 22 from being distorted.

  As described in the description of the conventional example, the outer member 1 is deformed by the load of the rolling element 5 that passes therethrough. In particular, the deformation due to the rolling element load is large on a line segment L (FIG. 1) that extends in the direction that forms the contact angle of the rolling element through the center of the rolling element 5. That is, it is easily affected by the rolling element load. In this sensor-equipped wheel bearing, the double-row rolling elements 5 of the sensor unit 20 are separated from the line segment L in which the strain generating member 21 extends in the direction passing through the center of the rolling elements 5 to form the rolling element contact angle. Of these, the strain generating member 21 of the sensor unit 20 is less affected by the rolling element load. Therefore, the deformation of the outer member 1 due to the original load can be accurately detected by the sensor unit 20, and the load acting between the tire of the wheel and the road surface can be accurately estimated by the load estimating means 30 from the output signal.

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 having a flat shape with a constant width over the entire length and having a notch portion 21b on the side portion. Strain is easily transmitted to the strain generating member 21 in an enlarged manner, and the strain is detected by the strain sensor 22 with high sensitivity. Hysteresis generated in the output signal is also reduced, so that the load can be estimated with high accuracy. Further, the shape of the strain generating member 21 can be simplified, and it can be made compact and low-cost and excellent in mass productivity.

  Further, in this embodiment, two sensor units 20 arranged at a position forming a phase difference of 180 degrees in the circumferential direction on the outer diameter surface of the outer member 1 which is a fixed side member are set as one set 2. Since the pair of sensor unit pairs 19A and 19B is 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 it is 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 strain sensor 22.

  6 to 8 show another embodiment of the present invention. In the sensor-equipped wheel bearing, in the embodiment shown in FIGS. 1 to 5, the correction means 31 for correcting the output signal of the strain sensor 22 of the sensor unit 20 is provided in the preceding stage of the load estimation means 30. In addition, on the inner periphery of the outer member 1, rolling element detection means 40 that detects the position of the rolling elements 5 in the inboard side row is provided. The rolling element detection unit 40 includes a plurality of rolling element sensors 42, and the correction unit 31 is connected to the strain sensor 22 of the sensor unit 20 and the rolling element sensor 42. Other configurations are the same as those of the embodiment shown in FIGS.

  The rolling element detecting means 40 is provided on the inner periphery of the outer member 1, and the front shape is an arc shape concentric with the bearing, as shown in the sectional view and the front view in FIGS. The sensor support member 41 and a plurality of rolling element sensors 42 attached to the sensor support member 41. The sensor support member 41 has an L-shaped cross section having a cylindrical portion 41a fitted to the inner diameter surface of the outer member 1 and a standing plate portion 41b extending from one end of the cylindrical portion 41a toward the inner diameter side. The circumferential length of 41b is a length corresponding to the arrangement pitch P of the rolling elements 5. As shown in FIG. 6, the sensor support member 41 has an upright plate portion 41 b positioned in the axial direction on the inboard side with respect to the rolling surface 4 in the inboard side row, and is axially aligned with the rolling elements 5 in the inboard side row Is attached to the inner diameter surface of the outer member 1 so as to face the outer surface. As shown in FIG. 7B, the plurality of rolling element sensors 42 are mounted on the one side of the sensor support member 41 facing the outboard side so as to be equally distributed in the circumferential direction. As the rolling element sensor 42, for example, a magnetic sensor such as a Hall sensor, MR sensor, or MI sensor is used, and a magnetic change accompanying the rolling element 5 passing through the front surface thereof is detected.

The correction means 31 is a means for correcting the output signal of the strain sensor 22 of the sensor unit 20 based on the rolling element position detected by the rolling element detection means 40, that is, the output signal of the rolling element sensor 42.
As described above, by devising the installation position of the sensor unit 20, the output signal of the strain sensor 22 of the sensor unit 20 can reduce the influence of the rolling element 5 that passes through, but the influence still remains. That is, during the rotation of the wheel bearing, a periodic change as shown in the waveform diagram of FIG. 5 occurs in the amplitude of the output signal of the strain sensor 22 of the sensor unit 20. Even when the bearing is stopped, the output signal of the strain sensor 22 is affected by the position of the rolling element 5. That is, when the rolling element 5 passes through the position closest to the strain sensor 22 in the sensor unit 20 as shown in FIGS. 8A and 8B (or when the rolling element 5 is at that position), the strain sensor 22. The output signal has a maximum amplitude and decreases as the rolling element 5 moves away from the position (or when the rolling element 5 is located away from the position). When the bearing rotates, the rolling elements 5 sequentially pass through the vicinity of the installation portion of the sensor unit 20 at a predetermined arrangement pitch P. Therefore, the output signal of the strain sensor 22 has an amplitude whose period is the arrangement pitch P of the rolling elements 5. As shown by a solid line in FIG. 8C, the waveform changes periodically. Therefore, the correction means 31 corrects the output signal of the strain sensor 22 as follows according to the rolling element position detected by the rolling element detection means 40. That is, for example, when the rolling element 5 is located closest to the strain sensor 22, the amplitude (maximum value at this time) of the output signal of the strain sensor 22 is corrected to decrease by a predetermined maximum value. When the rolling element 5 is located at a position ± P / 2 away from the position closest to the strain sensor 22, the amplitude of the output signal of the strain sensor 22 (at this time, the minimum value) is corrected to increase by a predetermined maximum amount. When the rolling element 5 is in the middle of both the positions, the amplitude of the output signal of the strain sensor 22 is corrected to increase or decrease by linear interpolation or the like according to the position. Thereby, the amplitude of the output signal of the strain sensor 22 is corrected as indicated by a chain line in FIG. 8C, and the influence of the rolling element 5 is eliminated.

  Even if the installation position of the sensor unit 20 is devised, the influence of the position of the rolling element 5 remains in the output signal of the strain sensor 22 of the sensor unit 20, but in this case, the position of the rolling element detected by the rolling element detection means 40 is not detected. Since the correction means 31 corrects the output signal of the strain sensor 22 based on this, the influence of the position of the rolling element 5 is eliminated regardless of whether the bearing is rotating or stopped. As a result, the load estimating means 30 can accurately estimate the loads acting on the wheel bearings and the tires of the wheels and the road surface (vertical load Fz, load Fx serving as driving force and braking force, and axial load Fy). .

  9 and 10 show still another embodiment of the present invention. In this sensor-equipped wheel bearing, in the embodiment of FIGS. 6 to 8, an averaging processing means 33 that averages the output signal of the strain sensor 22 is provided as a correction means before the load estimation means 30. A rotation detector 43 that detects the rotation of the inner member 2 is provided at an intermediate position in the axial direction in the bearing. The rotation detector 43 is a radial type and includes a pulsar ring 44 and a magnetic sensor 45. The averaging processing means 33 is connected to the strain sensor 22 of the sensor unit 20 and the magnetic sensor 45 of the rotation detector 43. Other configurations are the same as those of the embodiment shown in FIGS.

  The rotation detector 43 includes a pulsar ring 44 that is a sensor target fitted to the outer periphery of the inner member 1, and a magnetic sensor 45 that is provided on the inner periphery of the outer member 1 and faces the pulsar ring 44 in the radial direction. It consists of. Even if the pulsar ring 44 is a multipolar magnet in which the magnetic poles N and S are arranged in the circumferential direction, the pulsar ring 44 has a periodic magnetic change in the circumferential direction, such as a magnetic ring formed by arranging gear-shaped irregularities in the circumferential direction. It may be a thing. The magnetic sensor 45 detects a magnetic change of the pulsar ring 44 that rotates integrally with the inner member 2, and a Hall sensor, MR sensor, MI sensor, or the like is used.

  The averaging processing means 33 averages the amplitude of the output signal of the strain sensor 22 during the period in which the rolling elements 5 revolve around the arrangement pitch P as shown by the chain line in FIG. Is solved. The averaging process by the averaging processing unit 33 is performed as follows, for example. First, the rotational speed of the inner member 2 is calculated from the output signal of the magnetic sensor 45 of the rotation detector 43, and the required time T for the rolling elements 5 to revolve in the array pitch P is calculated from the calculated rotational speed. . Within this required time T, an arithmetic average of amplitude values of the output signal of the strain sensor 22 sampled at a predetermined period t is obtained. In this case, the sampling period t is sufficiently shorter than the required time T.

  As described above, the output signal of the strain sensor 22 remains affected by the passage of the rolling element 5 as it is, but in this case, since the averaging processing means 33 averages the output signal, the output of the rolling element passes. The effect is eliminated. As a result, the load estimating means 30 can accurately estimate the loads acting on the wheel bearings and the tires of the wheels and the road surface (vertical load Fz, load Fx serving as driving force and braking force, and axial load Fy). .

  FIG. 11 shows still another embodiment of the present invention. In the sensor-equipped wheel bearing, in the embodiment of FIGS. 6 to 8, the strain sensor 22 of the sensor unit 20 is arranged in front of the load estimating means 30 according to the temperature of the wheel bearing or its surrounding temperature as the correcting means. The temperature correction means 34 for correcting the output signal is provided. Further, a temperature sensor 46 is provided in the vicinity of the installation portion of each sensor unit 20 on the outer diameter surface of the outer member 1 or on the outer surface side of the strain generating member 21 in the sensor unit 20. As the temperature sensor 46, for example, a thermistor or a platinum resistance element can be used. The strain sensor 22 and the temperature sensor 46 of the sensor unit 20 are connected to the temperature correction unit 34. Other configurations are the same as those of the embodiment shown in FIGS.

  The temperature correction unit 34 corrects the output signal of the strain sensor 22 of the corresponding sensor unit 20 based on the output signal of the temperature sensor 46. Therefore, the output signal of the strain sensor 22 corrected by the temperature correction unit 34 is input to the load estimation unit 30.

  Thus, in this embodiment, the temperature correction means 34 outputs the output of the strain sensor 22 according to the output signal of the temperature sensor 46 provided on the outer diameter surface of the outer member 1 or the strain generating member 21 of the sensor unit 20. Since the signal is corrected, the output signal of the strain sensor 22 is corrected in accordance with the measured values of the wheel bearing and its surrounding temperature, and the load can be estimated with high accuracy.

  12 to 14 show still another embodiment of the present invention. In this sensor-equipped wheel bearing, in the embodiment shown in FIGS. 1 to 5, a direction discriminating sensor 47 which is a means for discriminating the direction of the axial load Fy estimated by the load estimating unit 30 is provided. This direction determination sensor 47 is a sensor unit 55 having a strain generating member 56 and a sensor 57 attached to the strain generating member 56 and detecting the strain of the strain generating member 56 fixed to the outer member 1. .

  As shown in an enlarged view in FIG. 13, the distortion generating member 56 of the direction determination sensor 47 is formed by bending a plate material made of a metal material such as a steel material into an L shape, and the screw hole 14 in the flange 1 a of the outer member 1. , A radial piece 56a that faces the side surface facing the outboard side, and an axial piece 56b that faces the outer diameter surface of the outer member 1. The sensor 57 is fixed to one surface of the radial piece 56a. The strain generating member 56 is fastened by bolts 59 and 60 to the outer peripheral portion of the outer member 1 through spacers 58A and 58B. That is, the bolt 59 inserted from the bolt insertion hole 61 formed in the radial piece 56a into the bolt insertion hole 62 of the spacer 58A is provided in the vicinity of the vehicle body mounting screw hole 14 in the flange 1a of the outer member 1. The screw hole 63 is screwed. Further, the bolt 60 inserted through the bolt insertion hole 65 of another spacer 58B from the bolt insertion hole 64 formed in the axial piece 56b is screwed into the screw hole 66 provided on the outer diameter surface of the outer member 1. Let Thereby, the distortion generating member 56 is fastened to the outer member 1.

  The location of the direction determination sensor 47 is large in the amount of deformation with respect to the axial load Fy, but is small in the amount of deformation with respect to the radial load such as the vertical load Fz and the load Fx due to the driving force / braking force. is there. When installed at this location, the force acting on the direction discrimination sensor 47 is switched between the compression force and the pulling force. Therefore, for example, if the magnitude of the output signal is determined with respect to a predetermined threshold value, the direction of the axial load Fy is changed. Can be determined. The output signal of the direction determination sensor 47 is input to the load estimation means 30, and the load estimation means 30 determines the direction of the axial load Fy from the input signal.

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. It is a front view of the outward member of the wheel bearing with a sensor. It is an enlarged plan view of a sensor unit in the wheel bearing with sensor. FIG. 4 is a cross-sectional view taken along arrow IV-IV in FIG. 3. It is a wave form diagram of the output signal of the sensor unit in the bearing for wheels with the sensor. It is a figure showing combining the sectional view of the wheel bearing with a sensor concerning other embodiments of this invention, and the block diagram of the conceptual composition of the detection system. (A) is sectional drawing of the rolling element detection means in the wheel bearing with a sensor, (B) is the same front view. It is explanatory drawing of the influence of a rolling-element position with respect to the output signal of a sensor unit. It is a figure which combines and shows the sectional view of the wheel bearing with a sensor concerning further another embodiment of this invention, and the block diagram of the conceptual structure of the detection system. It is explanatory drawing of the influence of rolling element revolution with respect to the output signal of a sensor unit. It is a figure which combines and shows the sectional view of the wheel bearing with a sensor concerning further another embodiment of this invention, and the block diagram of the conceptual structure of the detection system. It is a figure which combines and shows the sectional view of the wheel bearing with a sensor concerning further another embodiment of this invention, and the block diagram of the conceptual structure of the detection system. It is a partially expanded sectional view of FIG. It is a front view of the outward member of the wheel bearing with a sensor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Outer member 1a ... Body mounting flange 2 ... Inner members 3, 4 ... Rolling surface 5 ... Rolling body 20 ... Sensor unit 21 ... Strain generating member 21a ... Contact fixing | fixed part 21b ... Notch part 22 ... Strain sensor 30 ... Load estimation means 31 ... Correction means 33 ... Averaging processing means (correction means)
34 ... Temperature correction means 47 ... Direction discrimination sensor (Axial load direction discrimination means)
56 ... Strain generating member 57 ... Sensor

Claims (11)

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 composed of sensors to be detected are arranged at positions where the strain generating member is out of a line segment extending in a direction passing through the center of the rolling element and forming a rolling element contact angle. A sensor-equipped wheel bearing, wherein the bearing for a wheel is provided at a position closer to the inboard side than the rolling element on the inboard side.   The sensor-equipped wheel bearing according to claim 1, wherein the fixed-side member is the outer member.   The sensor-equipped wheel bearing according to claim 1 or 2, wherein a plurality of the sensor units are provided.   4. The radial load and the wheel according to claim 1, wherein at least three sensor units are provided, and a radial load and a wheel acting in a radial direction of a wheel bearing or a tire from an output signal of a sensor of these sensor units are provided. Bearing for sensor or wheel bearing provided with load estimating means for estimating axial load acting in the axial direction of the bearing or tire.   5. The sensor unit according to claim 1, wherein the sensor unit is an upper surface portion, a lower surface portion, a right surface portion of an outer diameter surface of the fixed side member that is in a vertical position and a horizontal position with respect to a tire ground contact surface. And a wheel bearing with sensor arranged on the left side.   6. The sensor-equipped wheel bearing according to claim 1, wherein the strain generating member of the sensor unit is a thin plate material having a planar shape in a strip shape.   The sensor-equipped wheel bearing according to claim 6, wherein the strain generating member has a notch portion on a side portion.   The distortion generating member of the sensor unit according to any one of claims 1 to 7, wherein a maximum force that is assumed as an external force that acts on the stationary member or an acting force that acts between the tire and a road surface. A bearing for a wheel with a sensor which is not plastically deformed even in a state where a pressure is applied.   9. The sensor-equipped wheel bearing according to any one of claims 4 to 8, wherein correction means for correcting an output signal of the sensor of the sensor unit is provided before the load estimation means.   10. The sensor-equipped wheel bearing according to any one of claims 4 to 9, further comprising an axial load direction discriminating means for discriminating an axial load direction.   11. The L-shaped distortion generation according to claim 10, wherein the fixed-side member has a flange on a peripheral surface thereof, and the axial load direction determining means is provided across the peripheral surface of the fixed-side material and the flange. A sensor-equipped wheel bearing, which is a direction determination sensor having a member and a sensor that is attached to the strain generating member and detects the strain of the strain generating member.

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