JP2009075054A - Wheel bearing with sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wheel bearing with a sensor, capable of correctly detecting a load without the effect of hysteresis. <P>SOLUTION: The wheel bearing is composed of: an external member 1 provided with double-row running faces 3 on the internal circumference; an internal member 2 provided with a running faces 4 opposite to the running faces 3 on the outer circumference; double-row rolling members 5 which intervene between both the running faces 3, 4 facing each other. A sensor unit pair 19 constituted of two sensor units 20 is provided on the outer circumference of a fixed side member 1 of the external member 1 and the internal member 2. The two sensor units 20 are arranged at points with 180° phase difference in the circumferential direction of the fixed side member 1 and is provided with sensors 22 for detecting the deformations of deformation generating member 21. Two contact fixing parts 21a of the sensor units 20 are arranged, on the mutually same phases on the fixed side member 1 in the circumferential direction and an estimation means 40 estimates the load acting on the axle for the wheel bearing by the difference of output signal of the sensor 22 of two sensor units 20 in the sensor unit pair 19. <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 distortion of an outer diameter surface of an outer ring flange of the wheel bearing has been proposed (for example, Patent Document 1). . In addition, a wheel bearing has been proposed in which a strain generating member made of an L-shaped member is attached over the flange portion and the outer diameter portion of a fixed ring, and a strain gauge is attached to a part of the strain generating member (for example, Patent Documents). 2).
JP 2002-098138 A JP 2006-0777807 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 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. 10 occurs in the output signal.
Also, in the technique disclosed in Patent Document 2, the portion fixed to the flange surface of the distortion expanding mechanism made of an L-shaped member is affected by the sliding of the flange surface and the knuckle surface, so the same problem as described above. Occurs.
Further, when detecting the load Fz in the vertical direction acting on the wheel bearing, the amount of deformation of the fixed wheel with respect to the load Fz is small, so the amount of distortion is also small. With the above technique, the detection sensitivity is low and the load Fz cannot be detected with high accuracy.

  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 is an outer member in which a double row rolling surface is formed on the inner periphery, and an inner member in which a rolling surface opposite to the rolling surface is formed on the outer periphery, A double row rolling element interposed between the opposing rolling surfaces of both members, and rotatably supporting the wheel with respect to the vehicle body. A strain generating member having two contact fixing portions fixed in contact with the outer diameter surface is attached to the outer diameter surface of the fixed side member of the outer member and the inner member, and the strain generating member is attached to the strain generating member. A sensor unit having a sensor for detecting distortion of the lever generating member is provided. The two contact fixing portions of the sensor unit are arranged at the same phase position in the circumferential direction of the fixing side member.

  Thus, when the two contact fixing portions of the strain generating member in the sensor unit are fixed in the same phase in the circumferential direction with respect to the outer diameter surface of the fixed side member, the strain tends to concentrate on the strain generating member, The sensitivity is improved accordingly. Further, since the sensor unit is not fixed to the projecting piece of the vehicle body mounting flange, which is a main cause of hysteresis, the hysteresis generated in the output signal of the sensor is reduced.

  However, in such a configuration, the change of the output signal is small with respect to the change of 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, the cornering force Fy and the vertical load Fz) is applied to the wheel bearing.

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

The sensor-equipped wheel bearing according to the present invention includes an outer member in which double-row rolling surfaces are formed on the inner periphery, an inner member in which a rolling surface facing the rolling surface is formed on the outer periphery, and both members. In a wheel bearing for supporting a wheel rotatably with respect to a vehicle body, a fixed-side member of the outer member and the inner member is provided. At least one pair of sensor units consisting of two sensor units arranged at a position forming a phase difference of 180 degrees in the circumferential direction of the stationary member is provided on the outer diameter surface, and the sensor unit includes the stationary member. A strain generating member having two contact fixing portions fixed in contact with the outer diameter surface of the sensor, and a sensor attached to the strain generating member for detecting the strain of the strain generating member. The two contact fixing parts are An estimation means is provided which is disposed at the same phase position in the circumferential direction of the constant side member and estimates the load acting on the wheel bearing based on the difference between the sensor output signals of the two sensor units in the sensor unit pair. It is characterized by.
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. The amount of deformation that occurs in the outer member due to the application of load differs at each position in the axial direction, but here, the two contact fixing parts of the strain generating member in the two sensor units of the sensor unit pair are the circles of the outer member. Since the circumferentially fixed positions are fixed to each other, the distortion of the outer member is concentrated and transmitted to the distortion generating member, and the distortion is detected with high sensitivity by the sensor and is generated in the output signal. Hysteresis is also reduced. Moreover, since the estimation means estimates the load acting on the wheel bearing from the difference between the output signals of the two sensor units of the sensor unit pair, even when the output signal of each sensor unit has a drift due to temperature or noise, The influence of drift can be canceled or reduced.
In addition, the amount of strain increases as the load increases in the sensor unit installed near the load direction, but the amount of strain decreases as the load increases in the sensor unit installed in the anti-load direction. Therefore, an output signal with a large inclination can be obtained by taking the difference between the output signals of the two sensor units.
Further, when the load in a certain direction increases, the portion where the rolling element and the rolling surface are in contact with the portion which is not in contact appears with a phase difference of 180 degrees in the circumferential direction of the outer member. When the two sensor units are arranged with a phase difference of 180 degrees according to the above, the load is surely transmitted to either one of the sensor units from the rolling element through the outer member, so that the load can be reliably detected by the sensor unit.
Therefore, the load applied to the wheel can be accurately detected under any load condition without being affected by hysteresis.

  In the present invention, the two sensor units of the sensor unit pair are arranged on the upper surface portion and the lower surface portion of the outer diameter surface of the fixed side member that is in the vertical position with respect to the tire ground contact surface, and the estimation means includes the You may make it estimate the load of the perpendicular direction which acts on the wheel bearing from the output signal of the sensor of two sensor units. In this configuration, the load Fz 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 the sensor unit pair are arranged on the right surface portion and the left surface portion of the outer diameter surface of the fixed side member that are front and rear positions with respect to the tire ground contact surface, and the estimation means includes the You may make it estimate the load used as a driving force from the output signal of the sensor of two sensor units. In the case of this configuration, the load Fx as a driving force can be accurately detected under any load condition without being affected by hysteresis.

In the present invention, a cornering force detection sensor for detecting a cornering force acting on the wheel bearing is further provided, and the estimating means calculates the output signal component of the cornering force detection sensor from the difference between two output signals in the sensor unit pair. May be separated to estimate the vertical load or the driving force acting on the wheel bearing.
For the cornering force Fy, since the outer diameter of the fixed-side member is greatly deformed, only the cornering force Fy can be detected by the cornering force detection sensor without being affected by the load Fz in the vertical direction and the load Fx due to the driving force. . On the other hand, since the vertical load Fz and the load Fx due to the driving force are easily affected by the cornering force Fy, when the output signal of the cornering force detection sensor is separated from the difference between the two output signals in the sensor unit pair, The load Fz in the vertical direction and the load Fx caused by the driving force that are not affected by the cornering force Fy can be estimated.

In the present 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 cornering force detection sensor is attached to the strain generating member and the strain generating member to reduce the 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 The 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.
The cornering force detection sensor is installed at a portion having a large deformation amount with respect to the cornering force Fy but a small deformation amount with respect to the load Fz in the vertical direction and the load Fx due to the driving force. Thereby, only the cornering force Fy can be specified and detected by the cornering force detection sensor.

In this invention, one contact fixing part of the two contact fixing parts in the two sensor units of the sensor unit pair is the periphery of the rolling surface on the outboard side of the double row rolling surfaces. The other one contact fixing part may be arranged further on the outboard side than the one contact fixing part at the axial position.
In this way, one contact fixing portion of the strain generating member in the two sensor units of the sensor unit pair becomes the periphery of the rolling surface of the outboard side row on the outer diameter surface of the fixing side member (for example, the outer member). When arranged in the axial position, this axial position is a part where the load applied to the ground contact surface of the tire is transmitted from the inner member via the rolling elements, and therefore the part has a relatively large deformation amount. On the other hand, the other one contact fixing portion of the strain generating member is arranged at an axial position on the outboard side further than the one contact fixing portion, and this axial position is compared with the previous axial position. It becomes a part with a small amount of deformation. As a result, the distortion of the outer diameter surface of the outer member is enlarged and transmitted to the distortion generating member, and the enlarged distortion is detected by the sensor.

  In this invention, the distortion generating member of 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 at 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 this invention, the estimation means calculates the difference between the output signals of the sensors of the two sensor units from the absolute value of the output signals, the average value of the output signals, and the amplitude of the output signals. It is also possible to calculate at least one of them.
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, by measuring the period of the amplitude in the output signal by the estimating means, it is possible to detect the passing speed of the rolling element, that is, the rotational speed of the wheel. As described above, when the output signal varies, the load can be calculated from the average value or amplitude of the output signal. If no change is observed, the load can be calculated from the absolute value.

  The sensor-equipped wheel bearing according to the present invention includes an outer member in which double-row rolling surfaces are formed on the inner periphery, an inner member in which a rolling surface facing the rolling surface is formed on the outer periphery, and both members. In a wheel bearing for supporting a wheel rotatably with respect to a vehicle body, a fixed-side member of the outer member and the inner member is provided. At least one pair of sensor units consisting of two sensor units arranged at a position forming a phase difference of 180 degrees in the circumferential direction of the stationary member is provided on the outer diameter surface, and the sensor unit includes the stationary member. A strain generating member having two contact fixing portions fixed in contact with the outer diameter surface of the sensor, and a sensor attached to the strain generating member for detecting the strain of the strain generating member. The two contact fixing parts are Since the fixed member is disposed at the same phase position in the circumferential direction of the fixed member, and provided with an estimation means for estimating the load acting on the wheel bearing by the difference between the sensor output signals of the two sensor units in the sensor unit pair, Without being affected by hysteresis, the load applied to the wheel can be accurately detected under any load condition.

  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. The flange 1a is provided with bolt holes 14 which are female screw holes for mounting on the vehicle body at a plurality of locations in the circumferential direction. As a result, 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. FIG. 1 is a cross-sectional view taken along the line I-O-I 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 sensor unit pair 19 including two sensor units 20 is provided on the outer diameter surface of the outer member 1 that is a stationary 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. Here, by providing these two sensor units 20 at two locations, the upper surface portion and the lower surface portion, on the outer diameter surface of the outer member 1 that is positioned up and down with respect to the tire ground contact surface, the vertical acting on the wheel bearings. The load Fz in the direction is detected. Specifically, as shown in FIG. 2, one sensor unit 20 is arranged in the center between two adjacent flange protrusions 1aa on the upper surface portion of the outer diameter surface of the outer member 1, and the outer member Another sensor unit 20 is arranged at the center between two adjacent flange protrusions 1aa on the lower surface of the outer diameter surface of one.

As shown in an enlarged sectional view in FIG. 3, these sensor units 20 include 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. The strain generating member 21 is made of a metal material such as steel. The strain generating member 21 has two contact fixing portions 21a projecting toward the inner surface facing the outer diameter surface of the outer member 1 at both ends, and the outer diameter surface of the outer member 1 is formed by these contact fixing portions 21a. Fixed in contact with. 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. In order to stably fix the sensor unit 20 to the outer diameter surface of the outer member 1, a flat portion is provided at a location where the contact fixing portion 21 a of the strain generating member 21 is fixed to the outer diameter surface of the outer member 1. It is desirable to form.
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 23. Specifically, these bolts 23 are respectively inserted into bolt insertion holes 24 that penetrate in the radial direction provided in the contact fixing portion 21 a, and are bolt holes 25 that are female screw holes provided in the outer peripheral portion of the outer member 1. Screwed on. In addition, as a fixing method of the contact fixing | fixed part 21a, you may use an adhesive agent etc. besides the fastening by the volt | bolt 23. FIG. 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.

  In addition to the sensor unit pair 19 described above, the outer member 1 is provided with a cornering force detection sensor 26 that detects a cornering force Fy acting on the wheel bearing. The cornering force detection sensor 26 includes a sensor unit 27 having a strain generating member 28 and a sensor 29 attached to the strain generating member 28 and detecting the strain of the strain generating member 28 via contact fixing portions 30A and 30B. It is fixed to the outer member 1.

  As shown in the enlarged sectional view of FIG. 4, the distortion generating member 28 of the cornering force detection sensor 26 is formed by bending a plate material made of a metal material such as a steel material into an L shape, and a bolt in the flange 1 a of the outer member 1. It has a radial piece 28 a that opposes the side face facing the outboard near the hole 14, and an axial piece 28 b that faces the outer diameter face of the outer member 1. The sensor 29 is fixed to one surface of the radial piece 28a. The strain generating member 28 is fastened to the outer peripheral portion of the outer member 1 with bolts 31 and 32 via two contact fixing portions 30A and 30B separated from the strain generating member 28. That is, the bolt 31 inserted into the bolt insertion hole 34 of the first contact fixing portion 30A from the bolt insertion hole 33 formed in the radial piece 28a is a bolt hole for the knuckle bolt 18 in the flange 1a of the outer member 1. 14 is screwed into a bolt hole 35 provided in the vicinity of 14. Further, the bolt 32 that is inserted in the bolt insertion hole 37 of the second contact fixing portion 30B from the bolt insertion hole 36 formed in the axial piece 28b is provided in the outer diameter surface of the outer member 1. Screwed on. Thereby, the strain generating member 28 is fastened to the outer member 1.

  The cornering force detection sensor 26 is installed at a portion having a large deformation amount with respect to the cornering force Fy but a small deformation amount with respect to the load Fx in the vertical direction and the load Fx due to the driving force. Therefore, only the cornering force Fy can be specified and detected by the cornering force detection sensor 26. However, the cornering force detection sensor 26 may not be limited to the above configuration.

  The two sensors 22 of the sensor unit pair 19 are connected to the estimation means 40. The estimation means 40 is a means for estimating the load acting on the wheel bearing based on the difference between the output signals of the two sensors 22 and includes a signal processing circuit, a correction circuit, and the like. Here, the estimating means 40 has relation setting means (not shown) in which the relation between the difference between the output signals and the vertical load Fz acting on the wheel bearing is set by an arithmetic expression or a table. The load Fz in the vertical direction is output from the difference between the output signals using the relationship setting means. The setting contents of the relationship setting means are obtained by a test or simulation in advance.

  A sensor 29 of the cornering force detection sensor 26 is also connected to the estimation means 40. The estimation means 40 corrects the difference between the output signals of the sensor 22 by separating the output signal of the cornering force detection sensor 26 from the difference between the output signals of the two sensors 22 of the sensor unit pair 19.

  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 body mounting flange 1a and the load is estimated from the deformation of the body mounting flange 1a, the output signal is output as described in the conventional example. Hysteresis occurs. Here, the two contact fixing portions 21 a of the strain generating member 21 in the two sensor units 20 of the sensor unit pair 19 are fixed at the same phase positions in the circumferential direction of the outer member 1. As a result, the distortion of the outer member 1 is concentrated and transmitted to the distortion generating member 21, and the distortion is detected with high sensitivity by the sensor 22, and the hysteresis generated in the output signal is also reduced.

The estimation means 40 estimates the vertical load Fz acting on the wheel bearing from the difference between the output signals of the sensors 22 of the two sensor units 20 of the sensor unit pair 19. FIG. 5 is a graph showing the relationship between the output signals of the two sensors 22 when the load Fz in the vertical direction changes in a state where the cornering force Fy is not acting on the wheel bearing. This graph shows a case where the output signal of each sensor 22 has no drift due to temperature or noise. The distortion occurs when the load Fz is zero because of the influence of the preload.
In the figure, when the load Fz in the vertical direction increases, the upper rolling element load (load applied to the rolling element 5) of the wheel bearing increases, so that the sensor disposed on the upper surface portion of the outer diameter surface of the outer member 1 is increased. The output signal of the sensor 22 in the unit 20 increases. On the other hand, since the lower rolling element load in the wheel bearing is reduced, the output signal of the sensor 22 in the sensor unit 20 disposed on the lower surface portion of the outer diameter surface of the outer member 1 is reduced. Therefore, when the difference between the output signals of the two sensors 22 is taken, an output curve having a large slope that increases as the load Fz increases is obtained. The estimation means 40 can estimate the vertical load Fz acting on the wheel bearing by comparing this difference output with the setting contents of the relation setting means described above. The acting force between the tire and the road surface can be accurately estimated.

  FIG. 6 is a graph showing the relationship between the output signals of the two sensors 22 when the vertical load Fz is changed in a state where the cornering force Fy is not applied to the wheel bearing. This graph shows a case where the output signal of each sensor 22 has a drift due to temperature or noise. Such drift due to temperature or the like occurs in the output signals of the two sensors 22 in the same way. Therefore, if the difference between the output signals of the two sensors 22 is taken, the drift is canceled. Thereby, the estimation means 40 can accurately estimate the load Fz in the vertical direction under any load condition without being affected by drift due to temperature and noise.

FIG. 7 is a graph showing the relationship between the output signals of the two sensors 22 when the vertical load Fz changes while a constant cornering force Fy is applied to the wheel bearing. This graph shows a case where the output signal of each sensor 22 has no drift due to temperature or noise. Compared with the graph of FIG. 5, the difference curves of the output signals of the sensors 22 of the two sensor units 20 of the sensor unit pair 19 have the same slope but different values at zero Fz load. This difference in value corresponds to the difference in the amount of distortion generated by the cornering force Fy.
The cornering force detection sensor 26 is not affected by the vertical load Fz or the load Fx due to the driving force because the outer surface of the outer member 1 that is the fixed member is greatly deformed with respect to the cornering force Fy. Only the cornering force Fy can be detected. On the other hand, since the vertical load Fz and the load Fx due to the driving force are easily affected by the cornering force Fy, the output of the cornering force detection sensor 26 is determined from the difference between the output signals of the two sensor units 20 in the sensor unit pair 19. When the signal component is separated, the vertical load Fz that is not affected by the cornering force Fy can be detected. Therefore, the estimation means 40 eliminates the difference in the amount of distortion generated by the cornering force Fy detected by the cornering force detection sensor 26 from the difference in the output signal of the sensor 22 so as not to be influenced by the cornering force Fy. The vertical load Fz can be accurately estimated.

  In FIGS. 5 to 7, the magnitude of the load Fz and the amount of strain are in a proportional relationship, but other cases are also conceivable. In any case, as described above, the estimation unit 40 estimates the vertical load Fz from the difference between the output signals of the two sensors 22 by using the relationship setting unit of the setting contents obtained in advance by tests and simulations. it can. The change in the slope of the difference curve of the output signal of the sensor 22 and the value when the distortion amount is zero in FIG.

  The estimation means 40 estimates the load acting on the wheel bearing from the output signal of the sensor 22. This makes it possible to detect the acting force between the wheel tire and the road surface with high sensitivity regardless of whether the vehicle is stationary or at low speed. As described above, since the sensor unit 19 is not fixed to the projecting piece 1aa of the vehicle body mounting flange 1a which is a main cause of hysteresis, the hysteresis generated in the output signal of the sensor 22 is reduced and the load is accurately estimated. can do.

  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, during the rotation of the wheel bearing, the amplitude of the output signal of the sensor 22 of the sensor unit 20 depends on the presence or absence of the rolling element 5 passing through the vicinity of the sensor unit 20 on the rolling surface 3 as 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 estimating means 40, it is possible to detect the passing speed of the rolling element 5, that is, the rotational speed of the wheel. As described above, when the output signal varies, the estimation unit 40 can calculate the difference between the output signals of the sensors 22 of the two sensor units 20 based on the average value and the amplitude of the output signals. If there is no change, it can be calculated from the absolute value.

  Further, in this embodiment, the notch 21b is provided in the strain generating member 21 of the sensor unit 20 in the sensor unit pair 19, and the sensor 22 is provided around the notch 21b. The strain transmitted from the outer diameter surface 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 estimated more accurately.

  Further, in this embodiment, the two sensor units 20 of the sensor unit pair 19 are arranged on the outer diameter surface of the outer member 1 between two adjacent projecting pieces 1aa of the wheel mounting flange 1a on the outer member 1. Since the sensor unit 20 is disposed at a position corresponding to the central portion, the sensor unit 20 is provided at a position away from the projecting piece 1aa that causes hysteresis, and the hysteresis of the output signal of the sensor 22 is further reduced, and the load is estimated more accurately. it can.

  FIG. 9: shows the front view which looked at the outward member 1 of the wheel bearing in other embodiment of this invention from the outboard side. In this embodiment, another sensor unit pair 19A is provided in the previous embodiment. This sensor unit pair 19 </ b> A also includes two sensor units 20 </ b> A arranged at a position that forms a phase difference of 180 degrees in the circumferential direction of the outer diameter surface of the outer member 1 that is a fixed member. In this case, the two sensor units 20A are arranged on the right surface portion and the left surface portion of the outer diameter surface of the outer member 1 that are in the front-rear position with respect to the tire installation surface. The configuration of the sensor unit 20A is the same as that of the sensor unit 20 in the previous embodiment. The sensors 22 of these two sensor units 20A are also connected to the estimation means 40. Other configurations are the same as those in the previous embodiment.

  By arranging the two sensor units 20A of the sensor unit pair 19A as described above, it is possible to detect the load Fx as a driving force. The estimation means 40 estimates the load Fx that becomes the driving force from the difference between the output signals of the sensors 22 of these sensor units 20A. For the load Fx, the left surface portion and the right surface portion of the outer diameter surface of the outer member 1 are deformed, so that the load Fx can be accurately estimated under any load condition. Also in the estimation of the load Fx as the driving force, when the cornering force Fy is applied, the correction is performed by the output signal of the cornering force detection sensor 26 as in the case of the estimation of the load Fz in the vertical direction.

It is sectional drawing of the bearing for wheels with a sensor concerning one Embodiment of this invention. It is a front view of the outward member in the wheel bearing with a sensor. It is an expanded sectional view of the sensor unit installation part in FIG. It is sectional drawing of the cornering force detection sensor installation part in the wheel bearing with the same sensor. It is the graph which showed the relationship of the output signal of a sensor unit when the load of a perpendicular direction changes in the state where cornering force is not acting. 6 is a grab showing a case where there is a drift in the output signal of the sensor unit in FIG. It is the graph which showed the relationship of the output signal of a sensor unit when the load of a perpendicular direction changes in the state where fixed cornering force is acting. 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 front view of the outward member in other embodiments. 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 14 ... Bolt hole 16 for body mounting ... Knuckles 19, 19A ... Sensor unit pair 20 , 20A ... sensor unit 21 ... strain generating member 21a ... contact fixing portion 21b ... notch 22 ... sensor 26 ... cornering force detection sensor 27 ... sensor unit 28 ... strain generating member 29 ... sensors 30A, 30B ... contact fixing portion 40 ... Estimating means

Claims (9)

An outer member having a double-row rolling surface formed on the inner periphery, an inner member having a rolling surface facing the rolling surface formed on the outer periphery, and interposed between the opposing rolling surfaces of both members. In a wheel bearing comprising a double row rolling element, and 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 includes a strain generating member having two contact fixing portions fixed in contact with the outer diameter surface of the fixed side member, and the strain generating member attached to the strain generating member. A sensor for detecting distortion; the two contact fixing portions of the sensor unit are arranged at the same phase position in the circumferential direction of the fixed side member, and the sensors of the two sensor units in the sensor unit pair A sensor-equipped wheel bearing, comprising: an estimation means for estimating a load acting on a wheel bearing based on a difference between output signals.   In Claim 1, the two sensor units of the sensor unit pair are arranged on the upper surface portion and the lower surface portion of the outer diameter surface of the fixed side member that is in the vertical position with respect to the tire ground contact surface, A sensor-equipped wheel bearing, wherein a vertical load acting on the wheel bearing is estimated from output signals of sensors of the two sensor units.   In Claim 1, the two sensor units of the 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 estimation means includes A sensor-equipped wheel bearing, wherein a load serving as a driving force is estimated from output signals of sensors of the two sensor units.   The cornering force detection sensor for detecting a cornering force acting on the wheel bearing is further provided according to any one of claims 1 to 3, wherein the estimation means is based on a difference between two output signals in the sensor unit pair. A sensor-equipped wheel bearing characterized in that the output signal of the cornering force detection sensor is separated to estimate a load acting as a driving force or a vertical load acting on the wheel bearing.   5. A flange for mounting a vehicle body attached to a knuckle is provided on an outer periphery of the fixed side member, and the cornering force detection sensor is attached to the strain generating member and the strain generating member. A sensor unit having a sensor for detecting the above 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. One contact fixing portion is fixed to a side surface of the flange, and the other one contact fixing portion is fixed to an outer diameter surface of the fixed side member.   6. The contact fixing part of the two sensor units of the sensor unit pair according to claim 1, wherein one of the contact fixing parts is an out of the double-row rolling surfaces. The sensor-equipped wheel bearing according to claim 1, wherein the other one contact fixing portion is arranged further on the outboard side than the one contact fixing portion at an axial position that is the periphery of the rolling surface on the board side.   The distortion generating member of the two sensor units of the sensor unit pair according to any one of claims 1 to 6, wherein the distortion generating member has a notch, and the sensor is provided around the notch. Features wheel bearing with sensor.   In any one of Claims 1 thru | or 7, The flange for the 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 portion provided with each bolt hole protrudes to the outer diameter side than the other portion, and the two sensor units of the sensor unit pair are respectively between the adjacent projecting pieces. A wheel bearing with sensor, characterized by being arranged in the center.   In any one of Claims 1 thru | or 8, The said estimation means is the difference of each output signal of the sensor of two sensor units, the absolute value of each said output signal, and the average value of each said output signal, And a sensor-equipped wheel bearing, wherein the bearing is calculated by at least one of the amplitudes of the output signals.

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