JP2009185888A - Wheel bearing with sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wheel bearing with a sensor accurately detecting a load on a wheel without being influenced by rolling elements. <P>SOLUTION: The wheel baring has the rolling elements 5 laid between opposed double row rolling surfaces 3, 4 of an outward member 1 and an inward member 2. It comprises a load detecting means 20 provided fixed-side one of the outward member 1 and the inward member 2 for detecting a load on the wheel bearing, a rolling element detecting means 40 for detecting the positions of the rolling elements, and a correcting means 30 for correcting an output signal from the load detecting means 20 in accordance with the positions of the rolling elements detected by the rolling element detecting means 40. Herein, an estimating means 31 is provided for estimating a load on a tire grounding surface or a load on the wheel bearing from the output signal from the load detecting means 20, corrected by the correcting means 30. <P>COPYRIGHT: (C)2009,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).

  Furthermore, a sensor unit comprising a strain generating member and a strain sensor attached to the strain generating member is attached to a fixed ring of the bearing, and the strain generating member has at least two contact fixing portions with respect to the fixed ring, A sensor-equipped wheel bearing has been proposed that 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 3).

According to the sensor-equipped wheel bearing disclosed in Patent Document 3, 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 2002-098138 A Special table 2003-530565 gazette JP 2007-57299 A

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 repeated loads are 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 that 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 in the portion where this deformation occurs, hysteresis as shown in FIG. 13 occurs in the output signal. When hysteresis occurs, the detection resolution decreases.
Further, as disclosed in Patent Document 2, there is a problem in assembling if the strain gauge is attached to the outer ring.
Moreover, in the wheel bearing with sensor disclosed in Patent Document 3, the amplitude of the output signal of the sensor unit increases every time the rolling element of the wheel bearing passes near the installation portion of the sensor unit. That is, the output signal of the sensor unit has 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 The load detecting means for detecting the load acting on the wheel bearing, the rolling element detecting means for detecting the position of the rolling element, and the load detecting means based on the rolling element position detected by the rolling element detecting means Correction means for correcting the output signal, and estimation means for estimating the load acting on the tire ground contact surface or the load acting on the wheel bearing from the output signal of the load detection means corrected by the correction means. It is characterized by.
When a load acts between a wheel bearing or a wheel tire and a road surface, the load is also applied to a stationary member (for example, an outer member) of the wheel bearing to cause deformation, and the load detection means applies the load from the deformation. To detect. The output signal of the load detection means is affected by the passage of the rolling element as it is, but the correction means corrects the output signal of the load detection means based on the position of the rolling element detected by the rolling element detection means. The effect of is eliminated. As a result, the estimation means becomes a load (vertical load Fz, driving force or braking force) that acts between the wheel bearing and the tire of the wheel and the road surface even when stopped without being affected by the rolling elements. The load Fx and the axial load Fy) can be accurately estimated.

In this invention, the said rolling element detection means may be comprised with the to-be-detected part provided in the holder | retainer, and the detection part which is provided in the said fixed side member and detects the said to-be-detected part.
In this way, the rolling element detection means for detecting the position of the rolling element detects the detected part provided in the cage having the same revolution speed as the rolling element and the detected part provided in the fixed member. If comprised with a detection part, the position detection of a rolling element will become easy.

In the present invention, the detected portion is composed of a magnetic encoder in which a plurality of magnetic poles N and S are alternately arranged in the circumferential direction, and the detecting portion has an electrical angle of 90 degrees or 270 with one magnetic pole pair of the magnetic encoder as one cycle. It may consist of two magnetic sensors arranged so as to have a phase difference of degrees.
Thus, if a to-be-detected part and a detection part are comprised, a rotation direction can be detected, the absolute angle of a holder | retainer can be detected, and the position of a rolling element can be detected correctly.

  In the present invention, the number of magnetic pole pairs of the magnetic encoder may be the same as the number of rolling elements. Thus, if the number of magnetic pole pairs of the magnetic encoder is the same as the number of rolling elements, the absolute angle can be detected for each arrangement pitch of the rolling elements, and the position detection accuracy of the rolling elements is improved accordingly.

  In the present invention, the load detecting means includes a strain generating member having two or more contact fixing portions fixed in contact with the fixed side member, and the strain generating member attached to the strain generating member. The contact fixing portion may be provided so as to have the same dimension in the axial direction with respect to the outer diameter surface of the fixing side member. In the case of this configuration, the distortion of the fixed-side member caused by the load acting between the wheel bearing and the tire of the wheel and the road surface is transmitted to the distortion generating member of the sensor unit. Can be detected with high sensitivity.

In the present invention, the strain generating member may be made of a strip having a uniform width in a planar shape or a thin plate material having a planar shape in a strip shape and having a notch in a side portion.
As described above, when the strain generating member is formed of a thin plate material having a planar shape with a uniform width, the strain generating member can be made compact and low cost.

  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 the case of this configuration, loads in a plurality of directions can be estimated. That is, 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 right side on the outer diameter surface of the fixed member. 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 surface portion and the left surface portion.

  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 The load detecting means for detecting the load acting on the wheel bearing, the rolling element detecting means for detecting the position of the rolling element, and the load detecting means based on the rolling element position detected by the rolling element detecting means Correction means for correcting the output signal, and estimation means for estimating the load acting on the tire contact surface or the load acting on the wheel bearing from the output signal of the load detection means corrected by the correction means. Without being affected by rolling elements, Also in the stop, the load acting on the wheel support bearing and the tire contact surface can be accurately detected.

  An 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. Bolt holes 14 for attaching knuckles are provided in the flange 1a at a plurality of locations in the circumferential direction, and the knuckle bolts 18 inserted through the bolt insertion holes 17 of the knuckle 16 from the inboard side are screwed into the bolt holes 14, thereby allowing the A mounting flange 1 a is attached to the knuckle 16.
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.

  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. As shown in FIG. 2, the vehicle body mounting flange 1 a is a projecting piece 1 aa in which a circumferential portion provided with each bolt hole 14 protrudes to the outer diameter side from the other portion.

  Four sensor units 20 are provided on the outer diameter surface of the outer member 1 which is a fixed member. Here, these sensor units 20 are provided on the upper surface portion, the lower surface portion, the right surface portion, and the left surface portion of the outer diameter surface of the outer member 1 that is in the vertical position and the front-rear position with respect to the tire ground contact surface.

  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 3 mm or less. 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 through spacers 23 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. Further, the notch 21b of the strain generating member 21 may be omitted. 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 the 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 24 via spacers 23, respectively. 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 bolt 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 this, and distortion deformation around the notch 21b becomes easy. 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. In order to stably fix the sensor unit 20 to the outer diameter surface of the outer member 1, a flat portion 1 b is formed at a location where the spacer 23 is contacted and fixed on the outer diameter surface of the outer member 1.

  In addition, as shown in a cross-sectional view in FIG. 5, grooves 1 c are provided at two intermediate portions where the two contact fixing portions 21 a of the strain generating member 21 are fixed on the outer diameter surface of the outer member 1. The spacer 23 may be omitted, and the intermediate portion of the two contact fixing portions 21b where the notches 21b of the strain generating member 21 are located may be separated from the outer diameter surface of the outer member 1.

  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.

  On the inner periphery of the outer member 1, there is provided a rolling element detection means 40 for detecting the position of the rolling elements 5 in the outboard side row. This rolling element detection means 40 includes a sensor support member 41 whose front shape is an arc concentric with the bearing, as shown in FIGS. 6A and 6B, and a sensor support member. A plurality of rolling element sensors 42 attached to 41. The sensor support member 41 has an inverted 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 the portion 41 b is a length corresponding to the arrangement pitch P of the rolling elements 5. As shown in FIG. 1, the sensor support member 41 has an upright plate portion 41 b that is positioned on the outboard side with respect to the rolling surface 4 on the outboard side row, and is axially aligned with the rolling elements 5 on the outboard side row. Is attached to the inner diameter surface of the outer member 1 so as to face the outer surface. The plurality of rolling element sensors 42 are mounted with equal distribution in the circumferential direction on one side facing the inboard side of the standing plate portion 41b of the sensor support member 41 as shown in FIG. 6B. 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. In addition, as the rolling element sensor 42, an ultrasonic sensor or an optical sensor may be used.

The strain sensor 22 of the sensor unit 20 and the rolling element sensor 42 of the rolling element detection means 40 are connected to the correction means 30, respectively. The correcting means 30 is a means for correcting the output signal of the strain sensor 22 of the sensor unit 20 which is a load detecting means based on the rolling element position detected by the rolling element detecting means 40, that is, the output signal of the rolling element sensor 42. .
Since the sensor unit 20 is provided at an axial position around the rolling surface 3 on the outboard side row of the outer member 1, the output signal of the strain sensor 22 is an installation portion of the sensor unit 20 as shown in FIG. 7. Is affected by the rolling element 5 passing through the vicinity of. 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. 7A and 7B (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. 7C, the waveform changes periodically. Therefore, the correction means 30 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 at a position closest to the strain sensor 22, the amplitude (the maximum value at this time) of the output signal of the strain sensor 22 is corrected to decrease by a predetermined maximum amount. When the rolling element 5 is located ± P / 2 away from the position closest to the strain sensor 22, the amplitude (minimum value at this time) of the output signal of the strain sensor 22 is corrected to be increased 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. 7C, and the influence of the rolling element 5 is eliminated. In FIG. 7A, the sensor unit 20 shown in the configuration example of FIG.

  In the description of FIG. 7, in order to simplify the description, the rolling element detection unit 40 determines the position of the rolling element 5 in the section of the rolling element arrangement pitch P before and after the position closest to the strain sensor 22. Although installed so as to detect, the position of the rolling element detection means 40 may be separated from the installation position of the sensor unit 20 in the circumferential direction. In this case, the position closest to the strain sensor 22 is corrected by correcting the rolling element position detected by the rolling element detection means 40 by the phase difference between the position of the rolling element detection means 40 and the installation position of the sensor unit 20. The position of the rolling element 5 in the section of the rolling element arrangement pitch P before and after the center can be determined.

  An estimation unit 31 is provided at the next stage of the correction unit 30. The estimation means 31 uses the output signal of the strain sensor 22 corrected by the correction means 30 to generate a force (vertical load Fz, driving force or braking force) acting on the wheel bearing or between the wheel and the road surface (tire contact surface). The load Fx and the axial load Fy) are estimated. The estimation means 31 sets the relationship among the vertical load Fz, the load Fx and the axial load Fy as driving force and braking force, and the output signal (corrected) of the strain sensor 22 by an arithmetic expression or a table. It has a relation setting means (not shown), and using the relation setting means from the corrected output signal of the strain sensor 22, an acting force (vertical load Fz, load Fx serving as driving force or braking force, axial load) Fy) is estimated. The setting contents of the relationship setting means are obtained by a test or simulation in advance.

  When a load acts between the wheel bearing or the wheel tire 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 having the notch portion 21b in the sensor unit 20 are fixed in contact with the outer member 1, the strain of the outer member 1 is enlarged and transmitted to the strain generating member 21. Then, the distortion is detected with high sensitivity by the distortion sensor 22, and the load can be estimated from the output signal. Here, the vertical load Fz and the axial load Fy can be estimated from the output signals of the two sensor units 20 arranged on the upper surface portion and the lower surface portion on the outer diameter surface of the outer member 1, and The load Fx caused by the driving force or the braking force can be estimated from the output signals of the two sensor units 20 arranged on the right surface portion and the left surface portion of the radial surface.

  In this case, the output signal of the strain sensor 22 is influenced by the position of the rolling element 5 as it is, but the correction means 30 corrects the output signal of the strain sensor 22 based on the rolling element position detected by the rolling element detection means 40. Therefore, the influence by the position of the rolling element 3 is eliminated regardless of whether the bearing is rotating or stopped. As a result, the estimating means 31 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). In addition, since no low-pass filter is required, the detection resolution is improved.

  If the axial dimension of each contact fixing portion 21a of the sensor unit 20 fixed to the outer diameter surface of the outer member 1 which is a fixed member is different, the outer diameter surface of the outer member 1 passes through the contact fixing portion 21a. The strain transmitted to the strain generating member 21 is also different. In this embodiment, the contact fixing portions 21 a of the sensor unit 20 are provided so as to have the same dimension in the axial direction with respect to the outer diameter surface of the outer member 1, so that strain concentrates on the strain generating member 21. The detection sensitivity is improved accordingly.

  In this embodiment, the strain generating member 21 of the sensor unit 20 is made of a strip having a uniform planar width, or a thin plate material having a planar planar shape and a cutout portion 21b on the side. Therefore, the distortion of the outer member 1 is easily transmitted to the distortion generating member 21, and the distortion is detected with high sensitivity by the distortion sensor 22. Hysteresis generated in the output signal is also reduced, and the load can be estimated with high accuracy. Further, the shape of the strain generating member 21 is also simple, and it can be made compact and low cost.

  In addition, since the corner of the notch 21b of the strain generating member 21 has an arcuate cross section, strain does not concentrate on the corner of the notch 21b, and the possibility of plastic deformation is reduced. Further, since the strain does not concentrate at the corner of the notch 21b, the variation in the strain distribution in the detection portion of the strain generating member 21, that is, the mounting portion of the strain sensor 22, is reduced, and the mounting position of the strain sensor 22 is distorted. The influence on the output signal of the sensor 22 is also reduced. Thereby, the load can be estimated with higher accuracy.

  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.

  Moreover, in this embodiment, the circumferential direction part in which the bolt hole 14 for knuckle attachment was provided in multiple places of the circumferential direction of the vehicle body attachment flange 1a of the outer member 1 which is a fixed side member is outside the other part. Although the projecting piece 1aa protrudes to the radial side, the two contact fixing portions 21a of the strain generating member 21 in the sensor unit 20 are arranged at the center between the adjacent projecting pieces 1aa, which causes the hysteresis. The strain generating member 21 is arranged at a position away from the protruding piece 1aa, and the hysteresis generated in the output signal of the strain sensor 22 is reduced accordingly, and the load can be estimated with higher accuracy.

  In this embodiment, the sensor unit 20 has an axial position around the outboard side rolling surface 3 of the double row rolling surfaces 3 in the outer member 1, that is, a relatively large installation space. Since the tire acting force is transmitted to the outer member 1 via the rolling elements 5 and disposed at a portion having a relatively large deformation amount, the detection sensitivity is improved, and the load can be estimated with higher accuracy.

  In this embodiment, since the sensor unit 20 is provided on the upper surface portion and the lower surface portion, and the right surface portion and the left surface portion of the outer diameter surface of the outer member 1 that is a fixed side member, under any load condition. The load can be estimated with high accuracy. 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.

In this embodiment, the following configuration is not particularly limited.
・ Number of sensor units 20 installed, location and number of contact fixing part 21a, strain sensor 22 and notch part 21b ・ Shape of sensor unit 20, fixing method (adhesion, welding, etc.), fixing direction (axial direction) Distortion may be detected)

  8 and 9 show another embodiment of the present invention. In this sensor-equipped wheel bearing, instead of the rolling element detection means 40 in the embodiment shown in FIGS. 1 to 7, a magnetic encoder 43 which is a detected portion provided in the cage 6 as shown in FIG. A rolling element detection means 40A is used which is provided on the inner periphery of the outer member 1 which is a side member and is configured by a detection unit 44 which detects a magnetic flux change of the magnetic encoder 43.

  FIG. 9 shows a front view of the rolling element detection means 40A. The magnetic encoder 43, which is a detected portion, has an annular shape that is concentric with the cage 6, and is formed by alternately arranging a plurality of magnetic poles N and S in the circumferential direction. The magnetic encoder 43 is an axial type in which the magnetic surfaces of the magnetic poles N and S are oriented in the axial direction. The number of magnetic pole pairs is the same as the number of rolling elements 5. FIG. 9 shows an example in which the number of magnetic pole pairs of the magnetic encoder 43 and the number of rolling elements 5 is nine. The detection unit 44 includes two magnetic sensors 44A and 44B arranged so as to have a phase difference of 90 degrees in electrical angle with the magnetic pole pair of the magnetic encoder 43 as one cycle, and these magnetic sensors 44A and 44B are It is attached to the inner diameter surface of the outer member 1 so as to face the magnetized surface in the axial direction with a predetermined interval. Here, since the magnetic encoder 43 is composed of nine magnetic pole pairs, the two magnetic sensors 44A and 44B of the detection unit 44 are separated in the circumferential direction by making a phase difference of 10 degrees in mechanical angle (space angle). Arranged. The magnetic sensors 44A and 44B include, for example, a hall sensor, an MR sensor, an MI sensor, or the like. The phase difference between the two magnetic sensors 44A and 44B may be a phase difference of 270 degrees in electrical angle (in the case of nine magnetic pole pairs, 30 degrees in mechanical angle (space angle)). Other configurations are the same as those of the embodiment shown in FIGS.

  In this embodiment, the rolling element detection means 40A for detecting the position of the rolling element 5 includes a detected portion (magnetic encoder 43) provided in the cage 6 having the same revolution speed as the rolling element 5, and a fixed side member. Since it is comprised with the detection part 44 provided in the outward member 1 which detects the said to-be-detected part (magnetic encoder 43), the position detection of the rolling element 5 becomes easy.

  In particular, a magnetic encoder 43 in which a plurality of magnetic poles N and S are alternately arranged in the circumferential direction is used as the detected portion, and the magnetic pole pair of the magnetic encoder 43 is arranged so as to have a phase difference of 90 degrees in terms of electrical angle. Since the two magnetic sensors 44A and 44B constitute the detection unit 44, the absolute angle of the cage 6 can be detected, and the position of the rolling element 5 can be accurately detected.

  Further, since the number of magnetic pole pairs of the magnetic encoder 43 is the same as the number of rolling elements 5, the absolute angle can be detected for each arrangement pitch P of the rolling elements 5, and the position detection accuracy of the rolling elements 5 is improved accordingly.

10 to 12 show still another embodiment of the present invention. In this sensor-equipped wheel bearing, in the embodiment shown in FIGS. 8 and 9, the sensor unit 20 is configured as follows. Also in this case, the sensor unit 20 includes a strain generating member 21 and a strain sensor 22 that is attached to the strain generating member 21 and detects the strain of the strain generating member 21, as shown in an enlarged sectional view in FIG. . The strain generating member 21 has two contact fixing portions 21a projecting on the inner surface facing the outer diameter surface of the outer member 1 at both ends, and these contact fixing portions 21a are formed on the outer diameter surface of the outer member 1. Fixed in contact. Of the two contact fixing portions 21a, one contact fixing portion 21a is disposed at an axial position around the rolling surface 3 of the outboard side row of the outer member 1, and is located on the outboard side from this position. Another contact fixing portion 21a is arranged at the position, and both the contact fixing portions 21a are arranged at the same phase position in the circumferential direction of the outer member 1. That is, the sensor unit 20 is arranged so that the two contact fixing portions 21a of the distortion generating member 21 are located at the same circumferential direction position of the outer member 1 that is the fixed side member and at positions separated from each other in the axial direction. The outer member 1 is arranged on the outer diameter surface. 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. Also in this case, in order to stably fix the sensor unit 20 to the outer diameter surface of the outer member 1, the contact fixing portion 21 a of the strain generating member 21 on the outer diameter surface of the outer member 1 is fixed at a location where the sensor unit 20 is fixed. It is desirable to form a flat part.
In addition, one notch portion 21 b that opens to the inner surface side is formed in the central portion of the strain generating member 21. 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 position around the notch portion 21b, specifically, the outer surface side of the strain generating member 21 and the back side of the notch portion 21b is selected, and the strain sensor 22 is the notch portion. The distortion around 21b is detected.

  The two contact fixing portions 21 a of the strain generating member 21 are fixed by being fastened to the outer diameter surface of the outer member 1 by bolts 47. Specifically, each of these bolts 47 is inserted into a bolt insertion hole 48 provided in the contact fixing portion 21a in the radial direction and screwed into a bolt hole 49 provided in the outer peripheral portion of the outer member 1. . In addition, as a fixing method of the contact fixing part 21a, in addition to fastening with the bolt 47, an adhesive or the like may be used. At locations other than the contact fixing portion 21 a of the strain generating member 21, a gap is generated between the outer member 1 and the outer diameter surface. Other configurations are the same as those of the embodiment shown in FIGS. FIG. 10 is a cross-sectional view taken along the line XX in FIG. 11 showing a front view of the outer member 1 of the wheel bearing as viewed from the outboard side. In this embodiment, the two sensor units 20 disposed on the right surface portion and the left surface portion of the outer diameter surface of the outer member 1 are omitted. Other configurations are the same as those of the embodiment shown in FIGS.

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 the front view which looked at the outer member of the wheel bearing with a sensor from the outboard side. 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 sectional drawing which shows the other example of installation of a sensor unit. (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 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. It is a front view of the rolling element detection means in the wheel bearing with a sensor. It is sectional drawing of the bearing for wheels with a sensor concerning further another embodiment of this invention. It is the front view which looked at the outer member of the wheel bearing with a sensor from the outboard side. It is an expanded sectional view of the sensor unit in the wheel bearing with the sensor. 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 2 ... Inner member 3, 4 ... Rolling surface 5 ... Rolling body 6 ... Cage 20 ... Sensor unit (load detection means)
DESCRIPTION OF SYMBOLS 21 ... Strain generating member 21a ... Contact fixing | fixed part 21b ... Notch part 22 ... Strain sensor 30 ... Correction means 31 ... Estimation means 40, 40A ... Rolling body detection means 43 ... Magnetic encoder (detected part)
44 ... Detectors 44A, 44B ... Magnetic sensor

Claims (7)

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,
A load detection means for detecting a load acting on a wheel bearing, provided on a fixed side member of the outer member and the inner member, a rolling element detection means for detecting a position of the rolling element, and the rolling element Correction means for correcting the output signal of the load detection means based on the rolling element position detected by the detection means, and a load or wheel bearing acting on the tire contact surface from the output signal of the load detection means corrected by the correction means A sensor-equipped wheel bearing, comprising: estimation means for estimating a load acting on the sensor.   The sensor-equipped wheel bearing according to claim 1, wherein the rolling element detection means includes a detected portion provided in a cage and a detection portion provided in the fixed-side member to detect the detected portion.   3. The detection target according to claim 2, wherein the detected part is composed of a magnetic encoder in which a plurality of magnetic poles N and S are alternately arranged in the circumferential direction. A sensor-equipped wheel bearing comprising two magnetic sensors arranged so as to have a phase difference of 270 degrees.   4. The wheel bearing with sensor according to claim 3, wherein the number of magnetic pole pairs of the magnetic encoder is the same as the number of rolling elements.   5. The strain generating member according to claim 1, wherein the load detecting means includes two or more contact fixing portions fixed in contact with the fixed side member, and the strain generating member. The sensor unit has a strain sensor that is attached and detects a strain of the strain generating member, and each of the contact fixing portions is provided so as to have the same dimension in the axial direction with respect to the outer diameter surface of the fixing side member. Bearing for wheel with sensor.   6. The sensor-equipped wheel bearing according to claim 5, wherein the strain generating member is a strip having a uniform planar width, or a thin plate material having a planar planar shape and having a notch in a side portion.   7. The sensor unit according to claim 5, wherein the sensor unit is disposed on an upper surface portion, a lower surface portion, a right surface portion, and a left 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. Bearing for sensor wheel.

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