JP5072551B2 - Wheel bearing with sensor - Google Patents

Description

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

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

In the technique disclosed in Patent Document 1, distortion generated by deformation of the flange portion of the fixed ring is detected. However, the deformation of the flange portion of the fixed ring involves slipping when a force exceeding the static friction force is applied between the flange surface and the knuckle surface, so that hysteresis is generated in the output signal when a repeated load is applied. There is a problem.
For example, when the load in a certain direction with respect to the wheel bearing increases, the static friction force between the fixed ring flange surface and the knuckle surface does not slip at first, but exceeds a certain size. And it comes to slip over the static friction force. If the load is reduced in this state, it will not slip due to static friction force at first, but it will slip when it reaches a certain size. As a result, when an attempt is made to estimate the load at a portion where this deformation occurs, a hysteresis as shown in FIG. 17 occurs in the output signal. When hysteresis occurs, the detection resolution decreases.
In addition, when a strain gauge is attached to the outer ring as in Patent Document 2, there is a problem in assemblability.
In addition, when detecting the vertical load Fz acting on the wheel bearing or tire, the amount of deformation of the fixed wheel relative to the load Fz is small, so the amount of distortion is small. It cannot be detected.

  Accordingly, the present inventors have developed a sensor-equipped wheel bearing having the following configuration in order to solve the above problems. The wheel bearing in this sensor-equipped wheel bearing includes an outer member having a double-row rolling surface formed on the inner periphery, and an inner member having a rolling surface opposite to the rolling surface formed on the outer periphery. And a double-row rolling element interposed between the opposing rolling surfaces of the two members, and supports the wheel rotatably with respect to the vehicle body. Of the outer member and the inner member, on the outer diameter surface of the fixed member, there are two contact fixing portions fixed in contact with the outer diameter surface, and a cut located between the two contact fixing portions. One or more sensor units having a strain generating member having a notch and a sensor attached to the strain generating member and detecting the strain of the strain generating member are provided.

  However, in such a configuration, the change in the output signal of the sensor is small with respect to the change in the load, and the detection error becomes large due to drift generated in the output signal due to temperature, noise, and the like. As a result, it is difficult to calculate the load in each direction in a state where a composite load (for example, cornering force Fy and vertical load Fz) is applied to the wheel bearing or tire.

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

A prerequisite configuration cell equipped wheel support bearing assembly capacitors of this invention, inner and outer member rolling run surfaces of the double row is formed on the inner periphery rolling run surface facing the raceway surface is formed on the outer periphery In a wheel bearing comprising a side member and a double-row rolling element interposed between the opposing rolling surfaces of both members, and for supporting the wheel rotatably with respect to the vehicle body, the outer member and the inner member At least one pair of sensor units including two sensor units arranged at a position forming a phase difference of 180 degrees in the circumferential direction of the fixed side member is provided on the outer diameter surface of the fixed side member, and the sensor unit Has a strain generating member having two or more contact fixing portions fixed in contact with the outer diameter surface of the fixed side member, and a sensor that is attached to the strain generating member and detects the strain of the strain generating member. And two in the sensor unit pair A radial load estimating means for estimating a radial load acting in the radial direction of a wheel bearing or a tire from a difference between sensor output signals of the sensor unit, and a sum of output signals of the sensors of the two sensor units in the sensor unit pair And an axial load estimating means for estimating an axial load acting in the axial direction of the wheel bearing or the tire.
When a load acts between the tire of the wheel and the road surface, the load is also applied to the fixed side member (for example, the outer member) of the wheel bearing, causing deformation. Here, since the two or more contact fixing portions of the strain generating members in the two sensor units constituting the sensor unit pair are contact fixed to the outer diameter surface of the outer member, distortion of the outer member is generated. The distortion is easily transmitted to the member, the distortion is detected with high sensitivity by the sensor, and the hysteresis generated in the output signal is also reduced.
In particular, at least one pair of sensor units each including two sensor units arranged at a position forming a phase difference of 180 degrees in the circumferential direction is provided on the outer diameter surface of the fixed member, and two of the sensor unit pairs are provided. A radial load estimating means for estimating, for example, a vertical load Fz, which is a radial load based on a difference between sensor output signals, and an axial load estimating means for estimating an axial load Fy based on the sum of the output signals of the two sensors. Therefore, the radial load (for example, the vertical load Fz) and the axial load Fy can be detected with high sensitivity and accuracy under any load condition without providing a large number of sensors.

  In the present invention, the two sensor units of at least one pair of sensor units are arranged on the upper surface portion and the lower surface portion of the outer diameter surface of the fixed side member that are vertically positioned with respect to the tire ground contact surface, and the radial direction The load estimating means may estimate a vertical load acting on the wheel bearing or the tire from a difference between output signals of the sensors of the two sensor units. In the case of this configuration, the load applied in the vertical direction can be accurately detected under any load condition without being affected by hysteresis.

  In the present invention, the two sensor units of at least one pair of sensor units are arranged on the right surface portion and the left surface portion of the outer diameter surface of the fixed side member which are front and rear positions with respect to the tire ground contact surface, and the radial direction The load estimation unit may estimate a load that is a driving force from a difference between output signals of the sensors of the two sensor units. In the case of this configuration, the load as the driving force can be accurately detected under any load condition without being affected by hysteresis.

Definitive first sensor with wheel bearing of the invention is to this invention, in the premise construction, the radial load estimating means, having a correction means for correcting the estimated value by the estimation value by the axial load estimating means The
The deformation amount of the fixed side member with respect to the radial load acting on the wheel bearing or the tire in the radial direction (the vertical load Fz or the load Fx serving as the driving force) is much larger than the deformation amount with respect to the axial load Fy. Since it is small, it is easily affected by the axial load Fy. Therefore, if the estimated value by the radial load estimating means is corrected by the estimated value by the axial load estimating means, the radial load can be estimated more accurately.

Definitive second sensor with wheel bearing of the invention is to this invention, in the premise construction, it is et in the axial load direction determining means for determining a direction of the axial load acting in the axial direction of the wheel bearing or tire The axial load estimating means acts in the axial direction of the wheel bearing or the tire from the sum of the output signals of the sensors of the two sensor units in the sensor unit pair and the discrimination result of the axial load direction discrimination means. you estimate the axial load to be.
When the sum of the sensor output signals of the two sensor units in the sensor unit pair calculated by the axial load estimating means is a V-shaped output curve (see FIG. 8) with respect to the axial load, the direction of the axial load Need to be determined. Therefore, if the axial load direction discriminating means is discriminated by the separately provided axial load direction discriminating means, the axial load estimating means accurately determines the axial load based on the discrimination result and the sum of the sensor output signals of the two sensor units. Can be detected.

  In the present invention, the axial load direction determining means may be a steering angle sensor for detecting a steering angle of the vehicle. In the case of this configuration, the cornering direction can be determined from the steering angle detected by the steering angle sensor, so that it is possible to determine the direction of the axial load.

  In the present invention, the axial load direction discriminating means may be a direction discriminating sensor having different output signals depending on the direction of the axial load acting in the axial direction of the wheel bearing or the tire. In the case of this configuration, since the output signal of the direction determination sensor differs depending on the direction of the axial load, the direction of the axial load can be determined from the output signal.

In this invention, a flange for mounting a vehicle body attached to a knuckle is provided on the outer periphery of the fixed side member, and the direction discrimination sensor is attached to the strain generating member and the strain generating member to detect the strain of the strain generating member. A sensor unit having a sensor to be mounted is attached to the fixed side member, and the strain generating member has two or more contact fixing portions fixed in contact with the fixed side member, and one of these contact fixing portions. One contact fixing portion may be fixed to the side surface of the flange, and the other one contact fixing portion may be fixed to the outer diameter surface of the fixed side member.
In this case, the direction discriminating sensor is installed at a portion having a large deformation amount with respect to the cornering force but a small deformation amount with respect to the radial load such as the vertical load Fz and the load Fx by the driving force. When installed in this area, the force acting on the direction detection sensor is switched between compression force and tensile force, so the output signal is monotonous from the maximum value of the negative axial load Fy to the maximum value of the positive axial load Fy. Increase (or monotonically decrease). 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 can be determined.

  In the present invention, the two contact fixing portions of the strain generating member in the two sensor units of the sensor unit pair are arranged at the same axial direction position of the fixed side member and at positions spaced apart from each other in the circumferential direction. May be. In the case of this configuration, the strain in the circumferential direction of the fixed side member can be detected by the sensor unit. That is, since the load acting between the tire and the road surface is transmitted from the rotation side member to the fixed side member via the rolling elements, the outer diameter surface of the fixed side member is distorted in the circumferential direction, and the contact fixing described above. The detection sensitivity is improved by the arrangement of the portions, and the load can be estimated with higher accuracy.

  In the present invention, the two sensor units of the pair of sensor units may be arranged at an axial position that is the periphery of the rolling surface on the outboard side of the double row rolling surfaces. In this configuration, since the installation space is relatively wide and the tire acting force is transmitted to the stationary member via the rolling elements and the sensor unit is disposed at a relatively large amount of deformation, the detection sensitivity is improved. Thus, the load can be estimated with higher accuracy.

  In this invention, the distortion generating member in the two sensor units of the sensor unit pair may have a notch, and the sensor may be provided around the notch. In the case of this configuration, the strain that is transmitted from the fixed member to the strain generating member is easily concentrated on the notch, the detection sensitivity of the sensor is improved, and the load can be detected with high accuracy.

  In this invention, a flange for mounting a vehicle body to be attached to a knuckle is provided on the outer periphery of the fixed side member, bolt holes are provided in a plurality of circumferential directions of the flange, and the flange is a circle in which each bolt hole is provided. The circumferential part may be a protruding piece that protrudes to the outer diameter side from the other part, and the two sensor units of the sensor unit pair may be arranged at the center between the adjacent protruding pieces. In the case of this configuration, the sensor unit is provided at a position away from the projecting piece causing the hysteresis, the hysteresis of the output signal of the sensor is further reduced, and the load can be detected with higher accuracy.

In the present invention, the radial load estimating means calculates the difference or sum of the output signals of the sensors of the two sensor units of the sensor unit pair, the absolute value of the output signals, and the average value of the output signals, Further, it may be calculated by at least one of the amplitudes of the output signals.
During the rotation of the wheel bearing, there may be a periodic change in the amplitude of the output signal of the sensor of the sensor unit depending on the presence or absence of rolling elements passing through the vicinity of the sensor unit on the rolling surface. Therefore, the passage speed of the rolling element, that is, the rotational speed of the wheel can be detected by measuring the period of the amplitude in the output signal by the radial load estimating means. As described above, when the output signal varies, the radial load can be calculated from the average value and amplitude of the output signal. When no fluctuation is observed, the radial load can be calculated from the absolute value.

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 At least one pair of sensor units each including two sensor units arranged at a position forming a phase difference of 180 degrees in the circumferential direction of the fixed side member is provided on the outer diameter surface of the fixed side member. A strain generating member having two or more contact fixing portions fixed in contact with the outer diameter surface of the member, and a sensor attached to the strain generating member to detect the strain of the strain generating member, and the sensor unit Two sensor units in a pair A radial load estimating means for estimating a radial load acting in the radial direction of the wheel bearing or the tire from the difference between the output signals of the sensors, and the wheel from the sum of the output signals of the sensors of the two sensor units in the sensor unit pair only set an axial load estimating means for estimating an axial load acting in the axial direction of the use bearings or tires (assuming configuration), the radial load estimating means estimates the estimation value by the axial load estimating means Correction means for correcting the value is provided. Alternatively, in the premise configuration, there is further provided an axial load direction discriminating means for discriminating the direction of the axial load acting in the axial direction of the wheel bearing or the tire, and the axial load estimating means comprises two sensor unit pairs. An axial load acting in the axial direction of the wheel bearing or the tire is estimated from the sum of the output signals of the sensors of the sensor unit and the determination result of the axial load direction determining means. For this reason, a small number of sensors, without being affected by the hysteresis, in any load condition, it is possible to accurately detect the load applied to the wheel.

  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 mounting the vehicle body are provided at a plurality of locations in the circumferential direction on the flange 1a, and knuckle bolts 18 inserted into the bolt insertion holes 17 of the knuckle 16 from the inboard side are screwed into the bolt holes 14. The vehicle body 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.

  A pair of sensor units 19 each including two sensor units 20 is provided on the outer diameter surface of the outer member 1 that is a fixed member. These two sensor units 20 are arranged at positions that form a phase difference of 180 degrees in the circumferential direction of the outer diameter surface of the outer member 1. One or more pairs of sensor units 19 may be provided. Here, the two sensor units 20 constituting the sensor unit pair 19 are provided at two positions on the outer diameter surface of the outer member 1 that is located above the tire ground contact surface, that is, the upper surface portion and the lower surface portion. A vertical load (vertical load) Fz or an axial load Fy acting on the bearing or tire is detected. Specifically, as shown in FIG. 2, one sensor unit 20 is arranged at the center between two adjacent projecting pieces 1 aa on the upper surface portion of the outer diameter surface of the outer member 1, and the outer member 1. Another one sensor unit 20 is arranged at the center portion between two adjacent projecting pieces 1aa on the lower surface portion of the outer diameter surface.

  As shown in FIGS. 3 and 4 in an enlarged plan view and an enlarged cross-sectional view, these sensor units 20 are a strain generating member 21 and a sensor that is attached to the strain generating member 21 and detects the strain of the strain generating member 21. 22 The strain generating member 21 is made of an elastically deformable metal thin plate material of 3 mm or less, such as a steel material, and has a flat planar shape 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 through spacers 23 at both ends. The 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 on the outer surface side of the strain generating member 21 is selected, and the sensor 22 detects the strain in the circumferential direction around the notch portion 21b. . Note that the strain generating member 21 is plastically deformed even in a state in which an assumed maximum force is applied as an external force acting on the outer member 1 that is a fixed member or an acting force acting between the tire and the road surface. It is desirable not to do so. This is because when 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. The assumed maximum force is, for example, the maximum force in a range where the function as a wheel bearing is not impaired by the application of the force.

  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 of the bolts 24 is inserted into a bolt insertion hole 26 of the spacer 23 from a bolt insertion hole 25 provided in the contact fixing portion 21a in the radial direction, 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.

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

  The two sensors 22 of the sensor unit pair 19 are respectively connected to the radial load estimating means 31 and the axial load estimating means 32 as shown in FIG. The radial load estimating means 31 is a means for estimating a radial load (in this case, the vertical load Fz) acting on the wheel bearing or the tire from the difference between the output signals of the two sensors 22. The axial load estimating means 32 is a means for estimating the axial load (corning force) Fy acting on the wheel bearing or the tire from the sum of the output signals of the two sensors 22.

The method for estimating the vertical load Fz by the radial load estimating means 31 and the method for estimating the axial load Fy by the axial load estimating means 32 will be described below. When the axial load Fy is zero and the vertical load Fz is applied, the deformation mode of the outer diameter surface of the outer member 1 is as shown by arrows P and Q in FIG. The upper surface portion of the outer diameter surface is deformed in the outer diameter direction, and the lower surface portion is deformed in the inner diameter direction. In this embodiment, the sensor unit 20 is arranged so that the two contact fixing portions 21a are at the same axial position on the outer diameter surface of the outer member 1 and spaced apart from each other in the circumferential direction. To detect the distortion. Thereby, the strain generating member 21 of the sensor unit 20 fixed to the upper surface portion is deformed in a pulling direction in which the strain increases, and the strain generating member 21 of the sensor unit 20 fixed to the lower surface portion has a small strain. Deforms in the compression direction. Therefore, when the difference between the output signals A and B (shown as a broken line graph in FIG. 7) of the two sensors 22 of the sensor unit pair 19 at this time is taken, the slope of the output signal A and B is shown as a solid line graph C in the same figure. A large output curve is obtained. Further, when the sum of the output signals A and B of the two sensors 22 is taken, an output curve with a small inclination is obtained as shown as another solid line graph D in FIG.
On the other hand, when the axial load Fy is applied in a state where the vertical load Fz is zero, the deformation mode of the outer diameter surface of the outer member 1 is as shown by arrows P and Q in FIG. Both the upper surface portion and the lower surface portion of the outer diameter surface of 1 are deformed in the outer diameter direction. As a result, both the strain generating member 21 of the sensor unit 20 fixed to the upper surface portion and the strain generating member 21 of the sensor unit 20 fixed to the lower surface portion are deformed in the pulling direction in which the strain increases. Therefore, when the difference between the output signals A and B (shown as broken line graphs in FIGS. 8 and 9) of the two sensors 22 of the sensor unit pair 19 at this time is taken, it is shown as a solid line graph C in the same figure. An output curve with a small slope is obtained. Further, when the sum of the output signals A and B of the two sensors 22 is taken, an output curve having a large inclination is obtained as shown by another solid line graph D.

Thus, the vertical direction by the radial load estimating means 31 is utilized by utilizing the fact that the deformation mode of the outer diameter surface of the outer member 1 is different between when the vertical load Fz is applied and when the axial load Fy is applied. The estimation of the load Fz and the axial load Fy by the axial load estimation means 32 are performed as follows.
(1) Axial load estimating means 32: The sum of the output signals A and B of the two sensors 22 is obtained, and the axial load (cornering force) Fy is estimated. In this case, the slope of the sum of the output signals A and B with respect to the vertical load Fz is small, and the amount of distortion of the axial load Fy is very large compared to the vertical load Fz. Not receive.
(2) Radial load estimation means 31: The difference between the output signals A and B of the two sensors 22 is obtained and corrected with the value of the axial load Fy obtained by the axial load estimation means 32 to obtain the vertical load Fz. presume. The amount of deformation of the outer member 1 is not limited to the vertical load Fz but compared to the amount of deformation with respect to the axial load Fy with respect to the radial load acting on the wheel bearing or the tire in the radial direction (including the load Fx as the driving force). Since it is very small, it is easily affected by the axial load Fy. Therefore, as described above, if the estimated value by the radial load estimating means 31 is corrected by the value of the axial load Fy obtained by the axial load estimating means 32, the radial load (in this case, the vertical load Fz) is accurately determined. Can be estimated. The radial load estimation unit 31 includes a correction unit 31a that performs the correction process. For example, when the vertical load Fz and the distortion amount are in a proportional relationship, the correction unit 31a corrects the offset amount and the inclination based on the value of the axial load Fy.

  The radial load estimating means 31 and the axial load estimating means 32 are the relationships (load Fz and strain amount (difference), load Fy and strain amount (sum) calculated in advance by experiments and analysis shown in FIGS. ), A relationship setting means (not shown) in which the load Fy and the strain amount (difference) are set by an arithmetic expression or a table. As a result, the radial load estimating means 31 and the axial load estimating means 32 calculate the vertical load Fz and the axial load Fy from the input output signals A and B of the two sensors 22 using the relationship setting means. Can be estimated.

  However, as shown by a V-shaped graph in FIG. 8, the strain generating member 21 of the sensor unit 20 is deformed in the pulling direction in both positive and negative directions (outboard side direction and inboard side direction) of the axial load Fy. In this case, it is necessary to determine the direction of the axial load Fy. As an example of this axial load direction discriminating means, a steering angle sensor 33 can be used as shown in FIG. Since the cornering direction is known from the steering angle detected by the sensor 33, the direction of the axial load Fy can be determined. The relational expression set in the relation setting means may include the direction of the axial load Fy.

  In addition, instead of the V-shaped graph as shown in FIG. 8, it increases monotonously (or decreases monotonously) from the maximum value of the negative axial load Fy to the maximum value of the positive axial load Fy as shown in FIG. If the sensor unit 20 can be installed in a proper place, the axial load Fy can be detected only from the output signals A and B of the sensor 22 of the sensor unit 20 without providing the axial load direction determining means such as the steering angle sensor 33 described above. The direction can also be determined.

  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. For example, when the sensor unit 20 of the sensor unit pair 19 is installed on the projecting piece 1aa of the vehicle body mounting flange 1a and the load is estimated from the deformation of the vehicle body mounting flange 1a, the output signal is output as in the description of the conventional example. Hysteresis occurs. Here, since the two contact fixing portions 21 a of the strain generating member 21 in the sensor unit 20 are contact fixed to the outer diameter surface of the outer member 1, the strain of the outer member 1 expands to the strain generating member 21. The distortion is detected by the sensor 22 with high sensitivity, the hysteresis generated in the output signal is reduced, and the load can be estimated with high accuracy.

  In particular, at least one pair of sensor units 19 including two sensor units 20 arranged at a position forming a phase difference of 180 degrees in the circumferential direction is provided on the outer diameter surface of the outer member 1 that is a fixed member. The radial load estimating means 31 for estimating, for example, the vertical load Fz, which is a radial load based on the difference between the output signals of the two sensors 22 of the sensor unit pair 19, and cornering by the sum of the output signals of the two sensors 22. Since the axial load estimating means 32 for estimating the axial load Fy as a force is provided, the radial load (in this case, the vertical load Fz) can be obtained under any load condition without providing a large number of sensors. The axial load Fy can be accurately estimated with high sensitivity.

In the above description, the case where the acting force between the wheel tire and the road surface is detected is shown, but 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 this embodiment, in the installation of the sensor unit 20 on the outer diameter surface of the outer member 1 that is a stationary member, the two contact fixing portions 21a of the distortion generating member 21 are connected to the same axis of the outer member 1. Since they are arranged so as to be in the directional position and spaced apart from each other in the circumferential direction, the circumferential distortion of the outer member 1 can be detected by the sensor unit 20. In the case of this embodiment, the load acting between the tire and the road surface is transmitted from the inner member 2 which is a rotation side member to the outer member 1 via the rolling elements 5, so that the outer diameter surface of the outer member 1 Is distorted in the circumferential direction, and the detection sensitivity is improved by the arrangement of the contact fixing portion 21a described above, and the load can be estimated with higher accuracy.

  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 sensor 22 is reduced accordingly, and the load can be estimated more accurately.

  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.

  Moreover, since the distortion generating member 21 of the two sensor units 20 of the sensor unit pair 19 has a notch portion 21b and the sensor 22 is provided around the notch portion 21b, an outer member that is a fixed side member. The strain transmitted from 1 to the strain generating member 21 is easily concentrated on the notch 21b, the detection sensitivity of the sensor 22 is improved, and the load can be detected with high accuracy.

  Further, during the rotation of the wheel bearing, depending on the presence or absence of the rolling element 5 passing through the vicinity of the sensor unit 20 on the rolling surface 3, the waveform shown in FIG. Periodic changes may occur as shown. This is because the amount of deformation differs between when the rolling element 5 passes and when it does not pass, and the amplitude of the output signal of the sensor 22 has a peak value for each passing period of the rolling element 5. Therefore, by measuring the period of this peak value in the detection signal by, for example, the radial load estimating means 31, it is possible to detect the passing speed of the rolling element 5, that is, the rotational speed of the wheel. Thus, when the output signal varies, the radial load estimating means 31 can calculate the difference between the output signals of the two sensors 22 of the sensor unit pair 19 from the average value and amplitude of each output signal. it can. When there is no change, it can be calculated from the absolute value.

In this embodiment, the following configuration is not particularly limited.
-Number of sensor units 20 installed, number of contact fixing parts 21a, sensors 22, notches 21b, installation location-Shape and fixing method of sensor unit 20 (bonding or welding may be used. The contact fixing portion 21a may be directly fixed to the outer diameter surface of the outer member 1, and a groove may be provided between the fixed portions of both contact fixing portions 21a on the outer diameter surface. (It is possible to detect the axial distortion)

  Further, in this embodiment, the two sensor units 20 that form the sensor unit pair 19 are formed by using an upper surface portion and a lower surface portion of the outer diameter surface of the outer member 1 that is a fixed side member that is positioned vertically with respect to the tire ground contact surface. However, the present invention is not limited to this, and it may be arranged on both the left and right sides of the outer diameter surface of the outer member 1. In this case, the radial load estimating means 31 can estimate the load Fx caused by the driving force acting in the longitudinal direction of the vehicle as the radial load.

  11 to 13 show another embodiment of the present invention. In this sensor-equipped wheel bearing, as the above-described axial load direction discriminating means, a direction discriminating sensor 34 having different output signals depending on the direction of the axial load Fy is provided in place of the steering angle sensor 33 in FIG. The direction discrimination sensor 34 here includes a sensor unit 35 having a strain generating member 36 and a sensor 37 that is attached to the strain generating member 36 and detects the strain of the strain generating member 36, and is attached via spacers 38A and 38B. It is fixed to the direction member 1.

  As shown in an enlarged view in FIG. 12, the strain generating member 36 of the direction determination sensor 34 is formed by bending a plate material made of a metal material such as a steel material into an L shape, and the bolt hole 14 in the flange 1 a of the outer member 1. , A radial piece 36a that faces the side surface facing the outboard side, and an axial piece 36b that faces the outer diameter surface of the outer member 1. The sensor 37 is fixed to one surface of the radial piece 36a. The strain generating member 36 is fastened with bolts 39 and 40 to the outer peripheral portion of the outer member 1 via spacers 38A and 38B. That is, the bolt 39 inserted through the bolt insertion hole 42 of the spacer 38A from the bolt insertion hole 41 formed in the radial piece 36a is provided in the vicinity of the bolt hole 14 for the knuckle bolt 18 in the flange 1a of the outer member 1. The bolt hole 43 is screwed. Further, the bolt 40 inserted from the bolt insertion hole 44 formed in the axial piece 36b into the bolt insertion hole 45 of another spacer 38B is screwed into the bolt hole 46 provided on the outer diameter surface of the outer member 1. Let Thereby, the distortion generating member 36 is fastened to the outer member 1.

  The installation part of the above-described direction discrimination sensor 34 is a part having a large deformation amount with respect to the cornering force but a small deformation amount with respect to the radial load such as the vertical load Fz and the load Fx by the driving force. When installed at this site, the force acting on the direction discrimination sensor 34 is switched between the compressive force and the pulling force, so that an output curve as shown by a broken line in FIG. 9 is obtained. 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 can be determined. The output signal of the direction determination sensor 34 is input to the axial load estimation means 32, and the axial load estimation means 32 determines the direction of the axial load Fy from the input signal. Other configurations are the same as those of the embodiment shown in FIGS.

14 to 16 show still another embodiment of the present invention. In this sensor-equipped wheel bearing, in the embodiment shown in FIGS. 1 to 10, the two sensor units 20 of the sensor unit pair 19 are configured as follows. Also in this case, the sensor unit 20 includes a strain generating member 21 and a 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. 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 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 21b, specifically, the position on the outer surface side of the strain generating member 21 and the back side of the notch 21b is selected, and the sensor 22 has the notch 21b. Detect peripheral distortion.

  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.

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 figure which combines and shows the front view of the outward member of the wheel bearing with a sensor, and the block diagram of a conceptual structure of a detection system. It is an enlarged plan view of a sensor unit in the wheel bearing with sensor. FIG. 4 is a sectional view taken along line IV-IV in FIG. 3. It is explanatory drawing which shows an example of the deformation | transformation mode of the outer member outer diameter surface of the wheel bearing with a sensor. It is explanatory drawing which shows the other example of the deformation | transformation mode of the outer member outer-diameter surface of the wheel bearing with a sensor. It is a graph which shows an example of the relationship between the sensor output and the vertical load in the wheel bearing with the sensor. It is a graph which shows an example of the relationship between the sensor output in the wheel bearing with a sensor, and an axial load. It is a graph which shows the other example of the relationship between the sensor output in the same wheel bearing with a sensor, and an axial load. 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. It is a partially expanded sectional view of FIG. It is a figure which combines and shows the front view of the outward member of the wheel bearing with a sensor, and the block diagram of a conceptual structure of a 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 figure which combines and shows the front view of the outward member of the wheel bearing with a sensor, and the block diagram of a conceptual structure of a detection system. It is a partially expanded sectional view of FIG. It is explanatory drawing of the hysteresis in the output signal in a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Outer member 1a ... Body mounting flange 1aa ... Projection piece 2 ... Inner member 3, 4 ... Rolling surface 5 ... Rolling body 19 ... Sensor unit pair 20 ... Sensor unit 21 ... Strain generating member 21a ... Contact fixing | fixed part 21b ... Notch 22 ... Sensor 31 ... Radial load estimation means 31a ... Correction means 32 ... Axial load designation means 33 ... Steering angle sensor (Axial load direction discrimination means)
34 ... Direction discriminating sensor (Axial load direction discriminating means)
35 ... Sensor unit 36 ... Distortion generating members 36aa, 36ba ... Contact fixing part 37 ... Sensor

Claims (15)

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 pair of sensor units comprising two sensor units disposed on the outer diameter surface of the fixed member of the outer member and the inner member at a position that forms a phase difference of 180 degrees in the circumferential direction of the fixed member. At least one pair, and the sensor unit has two or more contact fixing portions fixed in contact with the outer diameter surface of the fixed side member, and the strain generating member is attached to the strain generating member to generate the distortion. A radial load estimating means having a sensor for detecting a distortion of a member and estimating a radial load acting in a radial direction of a wheel bearing or a tire from a difference between output signals of sensors of two sensor units in the sensor unit pair And an axial load acting in the axial direction of the wheel bearing or tire from the sum of the sensor output signals of the two sensor units in the sensor unit pair. Only set an axial load estimating means for constant, the radial load estimating means, sensor wheeled characterized that you have a correction means for correcting the estimated value by the axial load estimating means that estimates bearing.   In Claim 1, two sensor units of at least one pair of sensor units are arranged on the upper surface portion and the lower surface portion of the outer diameter surface of the fixed side member which is in the vertical position with respect to the tire ground contact surface, and the diameter The directional load estimating means is a sensor-equipped wheel bearing that estimates a load in a vertical direction acting on the wheel bearing or the tire from a difference between output signals of the sensors of the two sensor units.   In Claim 1, two sensor units of at least one pair of sensor unit pairs are arranged on the right surface portion and the left surface portion of the outer diameter surface of the fixed side member that are in the front-rear position with respect to the tire ground contact surface, and the diameter The directional load estimating means is a sensor-equipped wheel bearing that estimates a load as a driving force from a difference between output signals of the sensors of the two sensor units. 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 pair of sensor units comprising two sensor units disposed on the outer diameter surface of the fixed member of the outer member and the inner member at a position that forms a phase difference of 180 degrees in the circumferential direction of the fixed member. At least one pair, and the sensor unit has two or more contact fixing portions fixed in contact with the outer diameter surface of the fixed side member, and the strain generating member is attached to the strain generating member to generate the distortion. A radial load estimating means having a sensor for detecting a distortion of a member and estimating a radial load acting in a radial direction of a wheel bearing or a tire from a difference between output signals of sensors of two sensor units in the sensor unit pair And an axial load acting in the axial direction of the wheel bearing or tire from the sum of the sensor output signals of the two sensor units in the sensor unit pair. Provided the axial load estimating means for constant, provided the axial load direction determining means for determining a direction of the axial load acting further in the axial direction of the wheel bearing or tire, the axial load estimating means, said sensor An axial load acting in the axial direction of the wheel bearing or tire is estimated from the sum of the output signals of the sensors of the two sensor units in the unit pair and the determination result of the axial load direction determination means. Wheel bearing with sensor. 5. The sensor unit according to claim 4, wherein the two sensor units of at least one pair of sensor units are arranged on an upper surface portion and a lower surface portion of the outer diameter surface of the fixed-side member that are vertically positioned with respect to a tire ground contact surface. The directional load estimating means is a sensor-equipped wheel bearing that estimates a load in a vertical direction acting on the wheel bearing or the tire from a difference between output signals of the sensors of the two sensor units. In Claim 4 , two sensor units of at least one pair of sensor units are arranged on a right surface portion and a left surface portion of an outer diameter surface of the fixed side member which are front and rear positions with respect to a tire ground contact surface, and the diameter The directional load estimating means is a sensor-equipped wheel bearing that estimates a load as a driving force from a difference between output signals of the sensors of the two sensor units. 5. The sensor-equipped wheel bearing according to claim 4, wherein the radial load estimating means includes correcting means for correcting the estimated value by the estimated value by the axial load estimating means. 8. The sensor-equipped wheel bearing according to claim 4 , wherein the axial load direction determining means is a steering angle sensor for detecting a steering angle of a vehicle. 8. The sensor according to claim 4 , wherein the axial load direction discriminating means is a direction discriminating sensor whose output signal differs depending on the direction of the axial load acting in the axial direction of the wheel bearing or the tire. Wheel bearing. In claim 9, the outer circumference of the stationary member, the flange of the vehicle body mounting is provided for mounting to the knuckle, the direction determination sensor is attached to the strain generating member and the strain generating member strain of the strain generating member A sensor unit having a sensor to be detected is attached to the fixed side member, and the strain generating member has two contact fixing portions fixed in contact with the fixed side member, and one of these contact fixing portions A sensor-equipped wheel bearing in which a contact fixing portion is fixed to a side surface of the flange, and another one contact fixing portion is fixed to an outer diameter surface of the fixed-side member. In any one of claims 1 to 10, two contact fixing segments of the strain generating member in the two sensor units of the sensor unit pairs, each other in a circumferential direction at the same axial position of the fixed-side member A wheel bearing with a sensor arranged so as to be spaced apart. The sensor-equipped wheel bearing according to claim 11 , wherein the sensor unit is disposed at an axial position around a rolling surface on the outboard side of the double row rolling surfaces. The sensor-equipped wheel according to any one of claims 1 to 12 , wherein the strain generating member in the two sensor units of the sensor unit pair has a notch, and the sensor is provided around the notch. Bearings. In any one of Claims 1 thru | or 13 , The flange for vehicle body attachment attached to a knuckle is provided in the outer periphery of the said fixed side member, The bolt hole is provided in the circumferential direction several places, The said The flange is a projecting piece in which the circumferential direction portion provided with each bolt hole protrudes to the outer diameter side from the other portion, and the two sensor units of the sensor unit pair are respectively between the adjacent projecting pieces. Wheel bearing with sensor placed in the center. The radial load estimation means according to any one of claims 1 to 14 , wherein the radial load estimation means calculates a difference or sum of the output signals of the sensors of the two sensor units of the sensor unit pair as an absolute value of each of the output signals. And a wheel bearing with sensor that is calculated by at least one of an average value of the output signals and an amplitude of the output signals.

Images