JP2015017888A - Wheel bearing device with sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable high accurate load detection by easing an influence of output fluctuation due to a circumferential direction position of a rolling body, and to enable sharing a sensor unit with many kinds of wheel bearings.SOLUTION: A rolling body 5 is interposed between rolling surfaces of an external member 1 and an internal member. On a fixing side member of both members, a sensor unit 20 composed of a distortion generating member 21 and distortion sensors 22A and 22B attached to the distortion generating member 21 is provided. The distortion generating member 21 has three contact fixing portions 21a aligned in a circumferential direction of the fixing side member and contact-fixed to the fixing side member, and the distortion sensors 22A and 22B are attached between the contact fixing portions 21a. On a peripheral surface of the fixing side member, two grooves 1c positioned between the contact fixing portions 21a are provided. A distance L between the groove width centers of both grooves 1c is made to be a straight line distance L between circumferential positions of two points C,C separating by an angle which is a half of an alignment pitch of the rolling body, in a touch diameter d which is a diameter of a point contacted by the rolling body on the fixing side member with a predetermined contacting angle.

Description

  The present invention relates to a sensor-equipped wheel bearing device including a load sensor that detects a load applied to a bearing portion of a wheel.

  As a technique for detecting a load applied to each wheel of an automobile, a wheel bearing has been proposed in which a strain gauge 51 is attached to an outer ring 50 of a wheel bearing as shown in FIG. Patent Document 1). In addition, a calculation method for estimating a load applied to a wheel from output signals of a plurality of strain sensors provided on the wheel has been proposed (for example, Patent Document 2).

  However, as disclosed in Patent Literature 1 and Patent Literature 2, when a load is detected using a strain sensor, the drift of the strain sensor due to the environmental temperature and the initial drift due to the strain accompanying the mounting of the strain sensor are detected. It becomes a factor to reduce.

  As a countermeasure for solving such a problem, as shown in FIG. 10, a sensor unit 70 including a strain generating member and a strain sensor attached to the strain generating member is attached to an outer ring 61 that is a fixed member of the wheel bearing 60. Sensor-equipped wheel bearings provided at two locations above and below the radial surface have been proposed (for example, Patent Document 3). The strain generating member has two contact fixing portions that are contact fixed to the outer diameter surface of the outer ring 61 and are spaced apart from each other in the circumferential direction of the outer ring 61, and the outer ring 61 is between these two contact fixing portions. It arrange | positions so that a non-contact state may be maintained with respect to.

  In the sensor-equipped wheel bearing disclosed in Patent Document 3, a decrease in detection accuracy due to drift is eliminated by filtering the output signal of the sensor unit 70, but the sensor unit 70 depends on the position of the rolling element of the wheel bearing. As a result, the load detection accuracy decreases when the vehicle is stationary or when the tire is locked.

  Therefore, for example, two strain sensors arranged in the circumferential direction of the outer ring are attached to the strain generating member in the sensor unit, and the distance between the two strain sensors is set to 1/2 the arrangement pitch of the rolling elements. A wheel bearing has been proposed (for example, Patent Document 4). In this case, the strain generating member is provided with three contact fixing portions arranged in the circumferential direction of the outer ring, and each strain sensor is attached between adjacent contact fixing portions. In addition, on the outer diameter surface of the outer ring, the first and second contact fixing parts adjacent to each other and the second contact fixing parts of the strain generating member are not in contact with the outer ring, and the first Grooves are respectively formed at two positions on the outer diameter surface of the outer ring corresponding to between the second and third contact fixing portions.

Special table 2003-530565 gazette Special table 2008-542735 gazette Japanese Patent No. 5085290 Japanese Patent No. 5094457

As in Patent Document 4, when the distance between the two strain sensors is ½ of the arrangement pitch of the rolling elements, there is an effect of eliminating the output fluctuation of the sensor unit due to the position of the rolling elements. However, the following issues still remain.
(1) Since the arrangement pitch of the rolling elements is different for each type of wheel bearing, the distance between the two strain sensors attached to the strain generating member in the sensor unit must be changed for each model number of the wheel bearing. Many types of sensor units are required.
(2) Even if the distance between the two strain sensors is ½ of the arrangement pitch of the rolling elements, the distance between the two grooves formed on the outer diameter surface of the outer ring corresponding to the two strain sensors is the arrangement of the rolling elements. If the pitch is not ½, the output fluctuation of the sensor unit due to the position of the rolling element may not be eliminated.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a sensor-equipped wheel that can reduce the influence of output fluctuation due to the circumferential position of the rolling element and can detect a load with high accuracy and can share a sensor unit with various types of wheel bearings. It is providing a bearing device for a vehicle.

The sensor-equipped wheel bearing device of the present invention has an outer member in which a double row rolling surface is formed on the inner periphery, an inner member in which a rolling surface opposite to the rolling surface is formed on the outer periphery, A wheel bearing having a double row rolling element interposed between opposing rolling surfaces of both members and rotatably supporting the wheel with respect to the vehicle body, the fixed side of the outer member and the inner member A strain generating member having two or more contact fixing portions fixed to the member in contact with the fixed side member, and one or more sensors attached to the strain generating member to detect strain of the strain generating member Three or more load detection sensor units are provided so that the respective contact fixing portions are arranged in the circumferential direction of the fixed side member, and in the orthogonal three-axis direction acting on the wheel bearing using the output signal of the sensor. Load estimation means for estimating the load is provided.
On the peripheral surface of the fixed member where the contact fixing portion is provided, at least two or more grooves are provided in parallel with each other and positioned between the contact fixing portions, and the groove widths of two adjacent grooves are The distance between the centers is n + 1/2 (n: an integer starting from 0) of the arrangement pitch of the rolling elements or the touch diameter, which is the diameter of the point where the rolling elements in the fixed member contact with a predetermined contact angle. The sensor is positioned within the groove width with a linear distance between two circumferential positions separated by an angle that approximates the value of. The above “n + ½ (n: integer starting from 0)” means that an interval of 1/2, 3/2, 5/2.

  As an example of the above configuration, the strain generating member has, for example, three contact fixing portions, the sensors are respectively mounted between the adjacent contact fixing portions, and the strain generation is generated on the peripheral surface of the fixed side member. The groove is provided between the adjacent first and second contact fixing portions of the member and between the adjacent second and third contact fixing portions.

  According to the wheel bearing device with a sensor having this configuration, the strain generating member having two or more contact fixing portions fixed in contact with the fixed side member, and the strain generating member attached to the strain generating member. Since three or more load detection sensor units comprising one or more sensors for detecting strain are provided so that the respective contact fixing portions are arranged in the circumferential direction of the fixed side member, the load estimating means causes the sensor By using the output signal, it is possible to accurately detect loads in the three orthogonal axes (vertical load Fz, load Fx serving as driving force and braking force, and axial load Fy) acting on the wheel bearing. That is, since the load detecting sensor unit detects the distortion of the fixed member by transferring it to the distortion generating member, the load detecting sensor unit can detect the distortion with high sensitivity by increasing the distortion. In addition, since three or more load detection sensor units are arranged in the circumferential direction of the fixed member, it is possible to detect loads in the orthogonal three-axis directions. The “load in the direction of three orthogonal axes acting on the wheel bearing” for performing the detection may be a force acting between the wheel and the tire ground contact surface of the road surface.

In this case, the peripheral surface of the fixed side member provided with the contact fixing portion is provided with a groove parallel to the axial direction so as to be positioned between the adjacent contact fixing portions. Since the rigidity is weaker than that of the portion, distortion is most likely to occur in the outer peripheral portion of the fixed side member. Therefore, when the sensor is disposed within the groove width, the distortion can be detected with high sensitivity and high accuracy.
As described above, the periphery of the groove is the most easily distorted portion, and the distance between the groove width centers of the two grooves that are the distortable portion is determined from n + 1/2 (n: 0) of the arrangement pitch of the rolling elements. If the linear distance between two circumferential positions separated by an angle (integer) is used, highly accurate load detection can be performed without being affected by the position of the rolling element. Since the rolling element contacts the fixed side member with a predetermined contact angle, two points separated by an angle that is n + 1/2 (n: an integer starting from 0) of the arrangement pitch of the rolling elements are Two points in the touch diameter, which is the diameter of the point of contact with a predetermined contact angle.

  Conventionally, it is defined by the distance between the positions of the sensors, but it has been found that the position of the fixed side member on which the sensors are mounted, for example, the groove of the outer member, is more important than the distance between the sensors. For this reason, in the present invention, the interval between the grooves is defined as ½ of the pitch of the rolling element array, but this increases the degree of freedom of the interval with respect to the rolling element pitch between the sensors in the sensor unit. It can be used for various types of wheel bearings, and can reduce the influence of output fluctuations due to the circumferential position of the rolling elements, enabling highly accurate load detection.

In this invention, the strain generating member is a plate-like member, and has notches on both sides of the sensor mounting position, and the width of the groove of the fixed side member is larger than the circumferential width of the notch. The notch portion may be accommodated within the groove width in a state where the sensor unit is provided on the stationary member.
When configured in this manner, the distortion of the fixed member is easily transmitted to the distortion generating member, and the distortion is detected with high sensitivity by the sensor, and the load can be estimated with high accuracy.

  In this invention, it is preferable that the sensor unit is provided at the same axial position as the position where the rolling member on the outboard side contacts the fixed member. When configured in this manner, the distortion of the fixed side member is easily concentrated on the distortion generating member, and the detection sensitivity is improved accordingly. In particular, when the fixed member is an outer member, the inboard side of the outer member is fitted to the knuckle, but the outboard side is in a free state, and there is no problem even if the groove is provided for strain detection. Does not occur.

In the present invention, the sensor unit is provided with a phase difference of 90 degrees in the circumferential direction on the upper surface portion, the lower surface portion, the right surface portion, and the left surface portion of the fixed side member that is in the vertical position and the horizontal position with respect to the tire ground contact surface. The load estimation means may estimate the radial load and the axial load acting in the radial direction and the axial direction of the wheel bearing using the output signals of the sensors of these sensor units.
When configured in this way, the vertical load Fz and the axial load Fy can be estimated from the output signals of the two sensor units arranged on the upper surface portion and the lower surface portion on the outer diameter surface of the fixed side member, The load Fx caused by the driving force or the braking force can be estimated from the output signals of the two sensor units arranged on the right surface portion and the left surface portion of the outer diameter surface.

  The sensor-equipped wheel bearing device of the present invention has an outer member in which a double row rolling surface is formed on the inner periphery, an inner member in which a rolling surface opposite to the rolling surface is formed on the outer periphery, A wheel bearing having a double row rolling element interposed between opposing rolling surfaces of both members and rotatably supporting the wheel with respect to the vehicle body, the fixed side of the outer member and the inner member A strain generating member having two or more contact fixing portions fixed to the member in contact with the fixed side member, and one or more sensors attached to the strain generating member to detect strain of the strain generating member Three or more load detection sensor units are provided so that the respective contact fixing portions are arranged in the circumferential direction of the fixed side member, and in the orthogonal three-axis direction acting on the wheel bearing using the output signal of the sensor. Load estimation means for estimating the load is provided, and the fixed On the peripheral surface of the member where the contact fixing part is provided, at least two grooves are provided parallel to the axial direction, respectively, between the contact fixing parts, and between the groove width centers of two adjacent grooves. For the touch diameter, which is the diameter of the point where the rolling elements of the fixed-side member contact with a predetermined contact angle, n + 1/2 of the arrangement pitch of the rolling elements (n: an integer starting from 0) or a value thereof. Since the linear distance between two circumferential positions separated by an approximate angle is used, and the sensor is positioned within the groove width, the influence of output fluctuations due to the circumferential position of the rolling element is reduced and high accuracy is achieved. Load detection is possible, and the sensor unit can be shared by many types of wheel bearings.

It is a figure showing combining the sectional view of the bearing device for wheels with a sensor concerning one embodiment of this invention, and the block diagram of the detection system. It is the front view which looked at the outward member of the bearing apparatus for wheels with the sensor from the outboard side. It is an enlarged plan view of a sensor unit in the sensor-equipped wheel bearing device. FIG. 4 is a cross-sectional view taken along arrow IV-IV in FIG. 3. It is explanatory drawing of the influence of a rolling-element position with respect to the output signal of the sensor unit of FIG. It is explanatory drawing of the touch diameter of the rolling element in an outer member. It is an enlarged plan view of another example of the sensor unit. It is explanatory drawing of the influence of a rolling-element position with respect to the output signal of the sensor unit of FIG. It is a perspective view of a prior art example. It is a front view of another prior art example.

  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 a cross-sectional view in FIG. 1, the bearing in the sensor-equipped wheel bearing device includes an outer member 1 in which a double row rolling surface 3 is formed on the inner periphery, and rolling members facing the respective rolling surfaces 3. The inner member 2 has a running 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 for attaching a knuckle at a plurality of locations in the circumferential direction, and knuckle bolts (not shown) inserted into the bolt insertion holes 17 of the knuckle 16 from the inboard side are screwed into the bolt holes 14. Thus, the vehicle body mounting flange 1a is attached to the knuckle 16.
The inner member 2 is a rotating side member, and includes a hub wheel 9 having a hub flange 9a for wheel mounting, and an inner ring 10 fitted to the outer periphery of the end portion on the inboard side of the shaft portion 9b of the hub wheel 9. And become. The hub wheel 9 and the inner ring 10 are formed with the rolling surfaces 4 of the respective rows. An inner ring fitting surface 12 having a small diameter with a step is provided on the outer periphery of the inboard side end of the hub wheel 9, and the inner ring 10 is fitted to the inner ring fitting surface 12. A through hole 11 is provided at the center of the hub wheel 9. The hub flange 9a is provided with press-fitting holes 15 for hub bolts (not shown) at a plurality of locations in the circumferential direction. In the vicinity of the base portion of the hub flange 9a of the hub wheel 9, a cylindrical pilot portion 13 for guiding a wheel and a braking component (not shown) protrudes toward the outboard side.

  FIG. 2 shows a front view of the outer member 1 of the wheel bearing as viewed from the outboard side. 1 shows a cross-sectional view taken along the line II in FIG. As shown in FIG. 2, the vehicle body mounting flange 1 a is a projecting piece 1 aa in which a circumferential portion provided with each bolt hole 14 protrudes to the outer diameter side from the other portion.

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

  As shown in the enlarged plan view and the enlarged cross-sectional view in FIGS. 3 and 4, these sensor units 20 are attached to the strain generating member 21 and detect the strain of the strain generating member 21. There are two or more (two in this case) strain sensors 22. The strain generating member 21 is made of an elastically deformable metal such as a steel material and is made of a thin plate material having a thickness of 3 mm or less. The strain generating member 21 is a strip having a uniform plane over the entire length and has notches 21b on both sides. The corner of the notch 21b has an arcuate cross section. Further, the strain generating member 21 has two or more (three in this case) contact fixing portions 21 a that are contact-fixed to the outer diameter surface of the outer member 1. The three contact fixing portions 21 a are arranged in a line in the longitudinal direction of the strain generating member 21. The two strain sensors 22 are affixed to the strain generating member 21 where the strain increases with respect to the load in each direction. Specifically, it arrange | positions between the contact fixing | fixed parts 21a adjacent on the outer surface side of the distortion generation member 21. FIG. That is, in FIG. 4, one strain sensor 22A is arranged between the contact fixing portion 21a at the left end and the contact fixing portion 21a at the center, and the other between the contact fixing portion 21a at the center and the contact fixing portion 21a at the right end. One strain sensor 22B is arranged. As shown in FIG. 3, the notch portions 21 b are formed at two positions corresponding to the placement portions of the strain sensor 22 on both side portions of the strain generating member 21. Thereby, the strain sensor 22 detects the strain in the longitudinal direction around the notch 21 b of the strain generating member 21. Note that the strain generating member 21 is plastically deformed even in a state in which an assumed maximum force is applied as an external force acting on the outer member 1 that is a fixed member or an acting force acting between the tire and the road surface. It is desirable not to do so. This is because when the plastic deformation occurs, the deformation of the outer member 1 is not transmitted to the sensor unit 20 and affects the measurement of strain.

In the sensor unit 20, the three contact fixing portions 21 a of the strain generating member 21 are positioned at the same dimension in the axial direction of the outer member 1, and each contact fixing portion 21 a is connected to the bolt 24 on the outer side of the outer member 1. Fixed to the radial surface.
Grooves 1c extending in parallel to the axial direction of the outer member 1 are provided at three intermediate portions where the three contact fixing portions 21a of the strain generating member 21 are fixed on the outer diameter surface of the outer member 1. . Thus, by providing the groove 1c on the outer diameter surface of the outer member 1, the rigidity around the groove 1c of the outer member 1 is weakened and the distortion is likely to occur, and the distortion is likely to occur. Since the sensor unit 20 contact fixing portion 21a is positioned, the sensitivity and accuracy of strain detection by the sensor unit 20 are improved. Moreover, each part which has the notch part 21b in the distortion generation member 21 which is thin plate-like will be in the state which left | separated from the outer-diameter surface of the outer member 1, and distortion deformation of the periphery of the notch part 21b will become easy. The sensors 22A and 22B of the sensor unit 20 are positioned within the groove width of each groove 1c. Further, the width dimension of the groove 1c is wider than the circumferential width of the notch 21b, and the notch 21b is within the width of the groove 1c with the sensor unit 20 provided on the outer member 1. It is supposed to be stored.

  Each of the bolts 24 is inserted into a bolt insertion hole 25 penetrating in the radial direction provided in the contact fixing portion 21a of the strain generating member 21, and screwed into a bolt hole 27 provided in the outer peripheral portion of the outer member 1. Let As the axial position where the sensor unit 20 is disposed, the position where the rolling elements 5 in the outboard side row of the outer member 1 are in contact is selected. 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 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. Is formed.

  The distance L (FIG. 5A) between the groove width centers of the two grooves 1c parallel to the axial direction provided on the outer diameter surface of the outer member 1 is the rotation of the outer member 1 as shown in FIG. At a touch diameter d, which is the diameter of the point T where the rolling elements 5 on the running surface 3 contact with each other with a predetermined contact angle, they are separated by an angle that is n + 1/2 (n: an integer starting from 0) of the arrangement pitch of the rolling elements 5. A straight line distance L between the circumferential positions of the points C and C (FIGS. 5A and 5B) is set.

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

The two strain sensors 22 of each sensor unit 20 are connected to the load estimating means 30. For example, the load estimating means 30 calculates the force (vertical load Fz, driving force or control force) acting on the wheel bearing or between the wheel and the road surface (tire contact surface) from the sum of the output signals of the two strain sensors 22 of the sensor unit 20. This is a means for estimating the load Fx and the axial load Fy). The load estimation means 30 sets the relationship between the vertical load Fz, the load Fx as a driving force and a braking force, the axial load Fy, and the sum of the output signals of the two strain sensors 22 by an arithmetic expression or a table. A relationship setting means (not shown), and using the relationship setting means based on the sum of the output signals of the two strain sensors 22, the acting force (vertical load Fz, load Fx serving as driving force or braking force, shaft Estimate the directional load Fy). The setting contents of the relationship setting means are obtained by a test or simulation in advance.
Note that the load estimation by the load estimating unit 30 is not limited to the above method using the sum of the output signals of the two strain sensors 22, and other methods such as a method using both data of the sum of the output signals and the difference between the output signals. Load estimation may be performed.

Since the sensor unit 20 is provided at the axial position of the outer member 1 where the rolling elements 5 in the outboard side row are in contact, the output signal A of the strain sensors 22A and 22B is the installation portion of the sensor unit 20 as shown in FIG. Is affected by the rolling element 5 passing through the vicinity of. Even when the bearing is stopped, the output signals A and B of the strain sensors 22A and 22B are affected by the position of the rolling element 5. That is, when the rolling element 5 is at the center position of the groove 1c of the outer member 1 (point C in FIG. 5B), the amplitude of the output signals A and B of the strain sensors 22A and 22B is the maximum value. As shown in FIGS. 5A and 5B, the rolling element 5 decreases as it moves away from the position (or when the rolling element 5 is at a position away from the position).
When the bearing rotates, the rolling elements 5 sequentially pass through the vicinity of the installation portion of the sensor unit 20 at a predetermined arrangement pitch P. Therefore, the amplitudes of the output signals A and B of the strain sensors 22A and 22B are arranged in the arrangement of the rolling elements 5. As shown by a solid line in FIG. 5C, the pitch P is a period, and the waveform is close to a sine wave that periodically changes.

The operation of the above embodiment will be described. 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 and is deformed. Three contact fixing portions 21a of the strain generating member 21 in the sensor unit 20 are fixed to the outer member 1, and the outer diameter surface of the outer member 1 is axially positioned at an intermediate position between the adjacent contact fixing portions 21a and 21a. Since the parallel grooves 1c are provided, the distortion of the outer member 1 is transmitted to the generating member 21 in an enlarged manner, the distortion is detected by the distortion sensors 22A and 22B, and the load can be estimated from the output signal.
In this embodiment, based on the sum of the output signals A and B of the two strain sensors 22A and 22B, the force (the vertical load Fz) that the load estimating means 30 acts on the wheel bearings and between the wheel and the road surface (tire contact surface). Therefore, the influence of the position of the rolling element 5 appearing in the output signals A and B of the two strain sensors 22A and 22B is offset. Thus, the load acting on the wheel bearing and the tire ground contact surface can be accurately detected.

In particular, a groove 1c is provided on the peripheral surface of the outer member 1 which is a fixed side member, provided between the adjacent contact fixing portions 21a and 21a, parallel to the axial direction on the peripheral surface. Since the peripheral portion of the groove 1c is weaker than other portions, the outer peripheral portion of the outer member 1 is most easily distorted. Therefore, when the sensor is disposed within the groove width of the groove 1c, the distortion can be detected with high sensitivity and high accuracy.
As described above, the periphery of the groove 1c is the most easily distorted portion, and the distance between the groove width centers of the two grooves 1c and 1c which are the easily distorted portion is expressed as n + 1/2 (the rolling element arrangement pitch P). n is an integer starting from 0), and is a linear distance between two circumferential positions separated by an angle such that the load can be detected with high accuracy without being affected by the position of the rolling element 5. Since the rolling elements 5 are in contact with the outer member 1 with a predetermined contact angle, two points C and C separated by an angle that is n + 1/2 (n: an integer starting from 0) of the arrangement pitch P of the rolling elements 5. Are two points on the touch diameter d, which is the diameter of the point T where the rolling element 5 contacts the rolling surface 3 with a predetermined contact angle.

Conventionally, it was defined by the interval between the positions of the sensors, but it was found that the position of the groove 1c of the outer member 1 for mounting the strain sensors 22A and 22B is actually more important than the distance between the sensors. . For this reason, in this embodiment, the interval L of the grooves 1c is defined as ½ of the pitch P of the rolling element arrangement, but this allows freedom in the interval between the strain sensors 22A and 22B in the sensor unit 20 with respect to the rolling element pitch P. For this reason, the sensor unit 20 can be shared by various types of wheel bearings, and the influence of output fluctuations due to the circumferential position of the rolling element 5 can be mitigated to enable highly accurate load detection.
That is, a force acting on the wheel bearing or between the wheel and the road surface (tire contact surface) estimated by the load estimating means 30 from the sum of the output signals A and B of the two strain sensors 22A and 22B (vertical load Fz, The load Fx and the axial load Fy) serving as the driving force and braking force are accurate with the influence of the position of the rolling element 5 eliminated more reliably.

  In addition, if the axial direction position of the sensor unit 20 fixed to the outer diameter surface of the outer member 1 which is a fixed side member is far from the position where the rolling element 5 is in contact with the outer member 1, the distortion of the outer member 1 is caused. The sensitivity transmitted to the strain generating member 21 is reduced. In this embodiment, since the sensor unit 20 is provided at the same axial position as the position where the rolling element 5 on the outboard side contacts the outer member 1, the distortion of the outer member 1 concentrates on the distortion generating member 21. The detection sensitivity is improved accordingly.

  Further, in this embodiment, the strain generating member 20 of the sensor unit 20 is formed of a strip having a uniform planar width, or a thin plate material having a planar planar shape and a notch portion 21b on the side. Therefore, the distortion of the outer member 1 is easily transmitted to the distortion generating member 21, and the distortion is detected with high sensitivity by the distortion sensors 22A and 22B, and the hysteresis generated in the output signals A and B is also reduced. It can be estimated with high accuracy. In addition, the shape of the strain generating member 21 is simple, and it is compact and low cost. Further, the width dimension of the groove 1c provided in the outer member 1 is wider than the circumferential width of the notch portion 21b, and the notch portion 21b is in a state where the sensor unit 20 is provided in the outer member 1. Since it is stored within the width of the groove 1c, distortion deformation around the notch 21b is further facilitated, and the load can be estimated with higher accuracy.

  By using the detected load obtained from the sensor-equipped wheel bearing device for vehicle control of the automobile, it is possible to contribute to stable running of the automobile. Further, when this sensor-equipped wheel bearing device is used, a load sensor can be compactly installed in the vehicle, the mass productivity can be improved, and the cost can be reduced.

In this embodiment, since the sensor unit 20 is provided on the upper surface portion and the lower surface portion, and the right surface portion and the left surface portion of the outer diameter surface of the outer member 1 that is a fixed side member, under any load condition. The load can be estimated with high accuracy. That is, when a load in a certain direction increases, a portion where the rolling element 5 and the rolling surface 3 are in contact with each other and a portion which is not in contact appear with a phase difference of 180 degrees. If installed with a degree phase difference, the load applied to the outer member 1 is always transmitted to one of the sensor units 20 via the rolling elements 5, and the load can be detected by the strain sensors 22A and 22B.
Further, the vertical load Fz and the axial load Fy can be estimated from the output signals of the two sensor units 20 arranged on the upper surface portion and the lower surface portion on the outer diameter surface of the outer member 1, and the outer diameter surface of the outer member 1. The load Fx caused by the driving force or the braking force can be estimated from the output signals of the two sensor units 20 arranged on the right surface portion and the left surface portion.

  FIG. 7 shows an example in which the same sensor unit 20 as that of FIG. 3 is fixed to the outer diameter surface of the outer member 1 in different types of wheel bearings. FIG. 8 shows an output signal of the sensor unit 20 in this case. Explanatory drawing of the influence of the rolling-element position with respect to is shown. That is, in this example, the arrangement pitch P of the rolling elements 5 is slightly larger than in the case of FIG. 3, and the distance between the centers of the two grooves 1c and 1c provided on the outer diameter surface of the outer member 1 is accordingly increased. It is getting longer. For this reason, the two strain sensors 22A and 22B attached to the strain generating member 21 are slightly shifted in the circumferential direction from the center of each groove 1c. However, the notches 21b formed on both sides of the strain generating material 21 are within the width of each groove 1c.

However, even in this case, the distance between the centers of the two adjacent grooves 1c and 1c is the touch diameter d, which is the diameter of the position where the rolling element 5 is in contact with the outer member 1 that is the fixed member, of the rolling element 5. The linear distance L between the circumferential positions of the two points C and C (FIG. 5), which is n + 1/2 of the arrangement pitch P (n: an integer starting from 0).
Thus, if the distance L between the centers of the grooves 1c, 1c formed in the outer member 1 is n + 1/2 (n: an integer starting from 0) of the arrangement pitch P at the touch diameter d of the rolling element 5, the detection element The pitch of the strain sensors 22A and 22B to be may be shifted from n + 1/2 (n: an integer starting from 0) of the arrangement pitch P of the rolling elements 5. However, the notch 21b needs to be within the range of the groove 1c.
Since the peripheral portion of the groove 1c provided in the outer member 1 is weaker than other portions, it is most easily distorted. Therefore, if the strain sensors 22A and 22B are installed within the width of the groove 1c, the strain measurement can be performed with the influence of the position of the rolling element 5 alleviated. As a result, the force (vertical load Fz) acting on the wheel bearing or between the wheel and the road surface (tire contact surface) estimated by the load estimating means 30 from the sum of the output signals A and B of the two strain sensors 22A and 22B. , The load Fx and the axial load Fy) serving as the driving force and the braking force are accurate with the influence of the position of the rolling element 5 eliminated more reliably. That is, even if the same sensor unit 20 is mounted on different types of wheel bearings to form a sensor-equipped wheel bearing device, accurate load detection is possible.

  In each of the above embodiments, in one sensor unit 20, the strain generating member 21 has three contact fixing portions 21a, and between the adjacent contact fixing portions 21a and 21a of the strain generating member 21, a strain sensor 22A. , 22B are attached, and an example in which two grooves 1c are provided on the outer diameter surface of the outer member 1 has been described. However, the sensor-equipped wheel bearing device according to the present invention is not limited to the above-described configuration example, and the strain generating member has two contact fixing portions, and one strain sensor is attached between the two contact fixing portions. Also applicable when using sensor units or sensor units where the strain generating member has four contact fixing parts and one strain sensor is attached between each of the adjacent contact fixing parts (total of three strain sensors). can do.

  That is, for example, when using a sensor unit in which the strain generating member has two contact fixing portions and one strain sensor is attached between the two contact fixing portions, the outer diameter surface of the outer member that is the fixed side member is 2 Two sensor units are provided side by side in the circumferential direction, and two grooves are provided on the outer diameter surface of the outer member so as to correspond to these sensor units, and the distance between the centers of the two grooves is determined by the rolling element in the outer member. In the case of the above embodiment, if the touch distance d, which is the diameter of the position where the contact points, is the linear distance L between the circumferential positions of the two points C and C (FIG. 5), which is ½ of the arrangement pitch of the rolling elements. The same effect can be obtained.

  In addition, when the strain generating member has four contact fixing portions and uses a sensor unit to which one strain sensor is attached for each of the adjacent contact fixing portions, between the adjacent contact fixing portions of the strain generating members. Correspondingly, three grooves are provided on the outer diameter surface of the outer member, and the distance between the centers of the first and second grooves and the distance between the centers of the second and third grooves are determined by the outer member. In the touch diameter d, which is the diameter of the position where the rolling elements in contact with each other, the linear distance L between the circumferential positions of the two points C and C (FIG. 5), which is ½ of the arrangement pitch of the rolling elements, is described above. The same effect as in the case of the form can be obtained.

DESCRIPTION OF SYMBOLS 1 ... Outer member 1c ... Groove 2 ... Inner member 3, 4 ... Rolling surface 5 ... Rolling body 20 ... Sensor unit 21 ... Strain generating member 21a ... Contact fixing | fixed part 21b ... Notch part 22,22A, 22B ... Strain Sensor 30 ... Load estimation means C ... Point d ... Touch diameter L ... Linear distance T ... Point

Claims (5)

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 strain generating member having two or more contact fixing portions fixed to the fixed side member of the outer member and the inner member in contact with the fixed side member, and attached to the strain generating member. Three or more load detection sensor units comprising one or more sensors for detecting strain of the strain generating member are provided so that the respective contact fixing portions are arranged in the circumferential direction of the fixed side member, and an output signal of the sensor is provided. A sensor-equipped wheel bearing device provided with load estimating means for estimating a load in three orthogonal directions acting on a wheel bearing,
On the peripheral surface of the fixed member where the contact fixing portion is provided, at least two or more grooves are provided in parallel with each other and positioned between the contact fixing portions, and the groove widths of two adjacent grooves are The distance between the centers is n + 1/2 (n: an integer starting from 0) of the arrangement pitch of the rolling elements or the touch diameter, which is the diameter of the point where the rolling elements in the fixed member contact with a predetermined contact angle. A sensor-equipped wheel bearing device, wherein the sensor is positioned within the groove width with a linear distance between two circumferential positions separated by an angle that approximates the value of.   2. The wheel bearing device with sensor according to claim 1, wherein the strain generating member has three contact fixing portions, the sensors are attached between the adjacent contact fixing portions, and the periphery of the fixed side member is set. The wheel bearing device with a sensor which provided the said groove | channel between the adjacent 1st and 2nd contact fixing | fixed part in the said distortion generation member and between the adjacent 2nd and 3rd contact fixing | fixed part in the surface respectively .   3. The sensor-equipped wheel bearing device according to claim 1, wherein the strain generating member is a plate-like member, and has notches on both sides of the sensor mounting position. The width of the groove of the fixed side member is wider than the circumferential width of the sensor, and the notched portion is accommodated in the groove width in a state where the sensor unit is provided in the fixed side member. Bearing device.   4. The sensor-equipped wheel bearing device according to claim 1, wherein the sensor unit is provided at the same axial position as a position where an outboard-side rolling element contacts the fixed-side member. Bearing device for wheels with sensor.   5. The sensor-equipped wheel bearing device according to claim 1, wherein the sensor unit includes an upper surface portion and a lower surface of the fixed side member that are in a vertical position and a horizontal position with respect to a tire ground contact surface. The four parts are equally arranged with a phase difference of 90 degrees in the circumferential direction on the right, left, and left surface parts, and the load estimation means uses the output signals of the sensors of these sensor units to determine the radial and axial directions of the wheel bearings. A wheel bearing device with a sensor for estimating a radial load and an axial load acting on the wheel.

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