JP5219423B2 - Wheel bearing with sensor - Google Patents

Description

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

As a technique for detecting a load applied to each wheel of an automobile, a sensor-equipped wheel bearing that detects a load by detecting 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 increasing mechanism composed of an L-shaped member is attached to the flange portion and the outer diameter portion of the fixed ring, and a strain gauge is attached to a part of the strain expanding mechanism (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. 5 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 that the amount of distortion is small.

  An object of the present invention is to provide a sensor-equipped wheel bearing capable of accurately detecting a load applied to a wheel 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. A strain generating member having two contact fixing portions fixed to the outer diameter surface in contact with the outer diameter surface, and a sensor unit having a sensor attached to the strain generating member and detecting the strain of the strain generating member. provided, characterized by being placed side by side each other in the axial direction in the same phase position in the circumferential direction of the two contact fixing segments is the stationary member to each other of the sensor unit.
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 with the application of a load differs at each position in the axial direction. Since the same phase is fixed in the circumferential direction, the strain tends to concentrate on the strain generating member, and the detection 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, and the load can be accurately detected. Thereby, it is possible to accurately detect the load applied to the wheel without being affected by hysteresis.

In the present invention, one of the two contact fixing portions may have another contact fixing portion at an axial position around the outboard rolling surface of the double row rolling surface. It is preferable that the contact fixing portion is disposed further on the outboard side than the one contact fixing portion.
Thus, when one contact fixing part of the distortion generating member in the sensor unit is fixed to an axial position around the rolling surface of the outboard side row on the outer diameter surface of the outer member, this axial position Is a part where the load applied to the ground contact surface of the tire is transmitted from the inner member through the rolling elements, and thus the part has a relatively large deformation amount. On the other hand, the other one contact fixing portion of the strain generating member is further fixed at an axial position on the outboard side than the one contact fixing portion, and this axial position is compared with the previous axial position. It becomes a site | part with a small deformation amount. 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 the present invention, the strain generating member of the sensor unit 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 portion may be a protruding piece that protrudes to the outer diameter side relative to the other portion, and the sensor unit may be disposed at the center between the adjacent protruding pieces. In the case of this configuration, the sensor unit is provided at a position away from the projecting piece causing the hysteresis, the hysteresis of the output signal of the sensor is further reduced, and the load can be detected with higher accuracy.

In the present invention, one of the sensor units may be provided on the upper surface portion of the outer diameter surface of the outer member with respect to the tire ground contact surface.
On the outer diameter surface of the outer member, even when a vertical load Fz or a longitudinal load Fy is applied, it is always in a position where the load of the rolling element is applied, that is, a position which is the upper surface portion with respect to the tire ground contact surface. If one sensor unit is provided, the load can be accurately detected in any case.

In this invention, the estimation means for estimating the load acting on the wheel bearing by at least one of the absolute value of the output signal of the sensor, the average value of the output signal, and the amplitude of the output signal. May be provided.
During the rotation of the wheel bearing, there may be a periodic change in the amplitude of the output signal of the sensor of the sensor unit depending on the presence or absence of rolling elements passing through the vicinity of the sensor unit on the rolling surface. Therefore, the passage speed of the rolling element, that is, the rotational speed of the wheel can be detected by measuring the period of the amplitude in the detection signal by the estimation means. 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.

In the present invention, the sensor unit may detect a vertical load Fz acting on the wheel bearing.
Since the sensor unit detects even a small strain in an enlarged manner, it can detect with high sensitivity even a vertical load Fz with a small deformation amount of the fixed member.

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. Provided on the outer peripheral surface is a strain generating member having two contact fixing parts fixed in contact with the outer peripheral surface, and a sensor unit having a sensor attached to the strain generating member and detecting distortion of the strain generating member, the said two contact fixing segments of the sensor unit is arranged in the axial direction from each other in phase position in the circumferential direction of the fixed-side member to each other because of the placement, accurately detect the load applied to the wheel without being affected by the hysteresis To do It can be.

  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 formed with the surface 4 and the double row rolling elements 5 interposed between the outer member 1 and the rolling surfaces 3 and 4 of the inner member 2 are constituted. This wheel bearing is a double-row angular ball bearing type, and the rolling elements 5 are made of balls and are held by a cage 6 for each row. The rolling surfaces 3 and 4 have an arc shape in cross section, and are formed so that the ball contact angle is aligned with the back surface. Both ends of the bearing space between the outer member 1 and the inner member 2 are sealed by a pair of seals 7 and 8, respectively.

The outer member 1 is a fixed side member, and has a vehicle body mounting flange 1a attached to a knuckle 16 in a suspension device (not shown) of the vehicle body on the outer periphery, and the whole is an integral part. Bolt holes 14 for mounting the vehicle body are provided at a plurality of locations in the circumferential direction on the flange 1a, and knuckle bolts 18 inserted into the bolt insertion holes 17 of the knuckle 16 from the inboard side are screwed into the bolt holes 14. The vehicle body mounting flange 1 a is attached to the knuckle 16.
The inner member 2 is a rotating side member, and includes a hub wheel 9 having a hub flange 9a for wheel mounting, and an inner ring 10 fitted to the outer periphery of the end portion on the inboard side of the shaft portion 9b of the hub wheel 9. And become. The hub wheel 9 and the inner ring 10 are formed with the rolling surfaces 4 of the respective rows. An inner ring fitting surface 12 having a small diameter with a step is provided on the outer periphery of the inboard side end of the hub wheel 9, and the inner ring 10 is fitted to the inner ring fitting surface 12. A through hole 11 is provided at the center of the hub wheel 9. The hub flange 9a is provided with press-fitting holes 15 for hub bolts (not shown) at a plurality of locations in the circumferential direction. In the vicinity of the base portion of the hub flange 9a of the hub wheel 9, a cylindrical pilot portion 13 for guiding a wheel and a braking component (not shown) protrudes toward the outboard side.

  FIG. 2 shows a front view of the outer member 1 of the wheel bearing as viewed from the outboard side. 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 19 is provided on the outer diameter surface of the outer member 1 that is a stationary member. Here, the two sensor units 19 are provided in two locations, the upper surface portion and the lower surface portion, on the outer diameter surface of the outer member 1 that are in the vertical position with respect to the tire ground contact surface, so that the vertical direction acts on the wheel bearing. The load Fz is detected. Specifically, as shown in FIG. 2, one sensor unit 19 is arranged at the center between two adjacent projecting pieces 1 aa on the upper surface portion of the outer diameter surface of the outer member 1, and the outer member 1. Another one sensor unit 19 is arranged at the center between the two adjacent projecting pieces 1aa on the lower surface portion of the outer diameter surface.

As shown in an enlarged sectional view in FIG. 3, these sensor units 19 include a strain generating member 20 and a sensor 21 that is attached to the strain generating member 20 and detects the strain of the strain generating member 20. The strain generating member 20 is made of a metal material such as a steel material. The strain generating member 20 has two contact fixing portions 20a projecting on the inner surface facing the outer diameter surface of the outer member 1 at both ends, and these contact fixing portions 20a are formed on the outer diameter surface of the outer member 1. Directly fixed. Of the two contact fixing portions 20a, one contact fixing portion 20a 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 20a is arranged at the position, and both the contact fixing portions 20a 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 of the inboard side row and the outboard side row to the formation portion of the rolling surface 3 of the outboard side row. is there. In order to stably fix the sensor unit 19 to the outer diameter surface of the outer member 1, a flat portion is provided at a location where the contact fixing portion 20 a of the strain generating member 20 is contact-fixed on the outer diameter surface of the outer member 1. It is desirable to form.
In addition, one notch portion 20 b that opens to the inner surface side is formed in the center portion of the strain generating member 20. The sensor 21 is affixed to a location where the strain increases with respect to the load in each direction in the strain generating member 20. Here, as the location, the position around the notch 20b, specifically the outer surface side of the strain generating member 20 and the back side of the notch 20b is selected, and the sensor 21 has the notch 20b. Detect peripheral distortion.

  The contact fixing portion 20a of the strain generating member 20 is fixed to the outer diameter surface of the outer member 1 by using a bolt 23 inserted through a bolt insertion hole 22 provided in the contact fixing portion 20a in the radial direction. 1 is screwed into a bolt hole 24 provided on the outer peripheral portion of the 1 and fastened, but may be fixed with an adhesive or the like. At locations other than the contact fixing portion 20a of the strain generating member 20, a gap is generated between the outer member 1 and the outer diameter surface.

  The sensor 21 of the sensor unit 19 is connected to the estimation means 25. The estimation means 25 is a means for estimating the acting force between the tire of the wheel and the road surface based on the output signal of the sensor 21, and includes a signal processing circuit and a correction circuit. The estimation means 25 has relationship setting means (not shown) in which the relationship between the acting force between the tire of the wheel and the road surface and the output signal of the sensor 21 is set by an arithmetic expression or a table or the like, and from the input output signal The acting force is output using the relationship setting means. The setting contents of the relationship setting means are obtained by a test or simulation in advance.

When a load acts between the tire of the wheel and the road surface, the load is also applied to the outer member 1 that is a stationary member of the wheel bearing, causing deformation. For example, when the sensor unit 19 is installed on the projecting piece 1aa of the vehicle body mounting flange 1a and the load is estimated from the deformation of the vehicle body mounting flange 1a, hysteresis occurs in the output signal as described in the conventional example.
Here, one contact fixing portion 20 a of the strain generating member 20 in the sensor unit 19 is fixed at an axial position that is the periphery of the rolling surface 3 of the outboard side row on the outer diameter surface of the outer member 1. This axial position is a portion where the load applied to the ground contact surface of the tire is transmitted from the inner member 2 via the rolling elements 5, and thus the portion having a relatively large amount of deformation. On the other hand, the other one contact fixing portion 20a of the strain generating member 20 is fixed to an axial position on the outboard side further than the one contact fixing portion 20a, and this axial position is the previous axial position. It becomes a part with a small deformation amount compared to. As a result, the distortion of the outer diameter surface of the outer member 1 is enlarged and transmitted to the distortion generating member 20, and the enlarged distortion is detected by the sensor 21. Further, the amount of deformation generated in the outer member 1 due to the application of a load is different at each position in the axial direction, but here, the two contact fixing portions 20 a of the strain generating member 20 in the sensor unit 19 are connected to the outer member 1. Since the same phase is fixed in the circumferential direction with respect to the outer diameter surface, the strain tends to concentrate on the strain generating member 20, and the detection sensitivity is improved accordingly.
The estimating means 25 estimates the load acting on the wheel bearing from the output signal of the sensor 21. 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 protrusion 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 21 is reduced, and the load is accurately estimated. can do.

The estimation means 25 may detect not only the acting force between the wheel tire and the road surface but also a force acting on the wheel bearing (for example, a preload amount).
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 21 of the sensor unit 19 depends on the presence or absence of the rolling element 5 passing through the vicinity of the sensor unit 19 on the rolling surface 3 as shown in FIG. Periodic changes may occur as shown. The reason is that the amount of deformation differs between when the rolling element 5 passes and when it does not, and the amplitude of the output signal of the sensor 21 has a peak value for each passing period of the rolling element 5. Therefore, by measuring the period of the peak value in the detection signal by, for example, the estimating means 25, 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 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.

  Moreover, in this embodiment, since the notch 20b is provided in the distortion generating member 20 of the sensor unit 19 and the sensor 21 is provided around the notch 20b, from the outer diameter surface of the outer member 1. The strain that is enlarged and transmitted to the strain generating member 20 is easily concentrated on the notch 20b, the detection sensitivity of the sensor 21 is improved, and the load can be estimated more accurately.

  In this embodiment, the sensor unit 19 is disposed on the outer diameter surface of the outer member 1 at a position corresponding to the center between the two adjacent projecting pieces 1aa of the wheel mounting flange 1a of the outer member 1. Therefore, the sensor unit 19 is provided at a position away from the projecting piece 1aa causing the hysteresis, the hysteresis of the output signal of the sensor 21 is further reduced, and the load can be estimated more accurately.

  Further, in this embodiment, even when a vertical load Fz or a longitudinal load Fy is applied to the outer diameter surface of the outer member 1, a position where the load of the rolling element 5 is always applied, that is, a tire ground contact surface. Since one sensor unit 19 is provided at a position that becomes the upper surface portion, the load can be accurately estimated in any case. Further, since the sensor unit 19 detects even a small strain in an enlarged manner, it can detect with high sensitivity even a load Fz in the vertical direction with a small deformation amount of the outer member 1.

In this embodiment, the following configuration is not particularly limited, and may be changed as appropriate.
Installation number and the number of sensor units 19, sensor 21, the number of notch 20b.
-The shape and fixing method of the sensor unit 19 (adhesion, welding, etc.).

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 a wave form diagram of the output signal of the sensor in the bearing for wheels with the sensor. It is explanatory drawing of the hysteresis in the output signal in a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Outer member 1a ... Car body mounting flange 1aa ... Projection piece 2 ... Inner member 3, 4 ... Rolling surface 5 ... Rolling body 14 ... Bolt hole 16 for vehicle body mounting ... Knuckle 19 ... Sensor unit 20 ... Strain generation Member 20a ... Contact fixing part 20b ... Notch 21 ... Sensor 25 ... Estimating means

Claims (8)

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 strain generating member having two contact fixing parts fixed to the outer diameter surface of the fixed side member of the outer member and the inner member in contact with the outer diameter surface, and the strain generating member. a sensor unit including a sensor for detecting the distortion of the strain generating member is provided, placed side by side each other in the axial direction to the two contact fixing segments is the position of the same phase in the circumferential direction of the fixed-side member to each other of the sensor unit A wheel bearing with a sensor characterized by the above.   The contact fixing part of one of the two contact fixing parts according to claim 1, wherein one of the two contact fixing parts is located at an axial position around the outboard rolling surface of the double row rolling surface. One contact fixing portion is a wheel bearing with a sensor arranged further on the outboard side than the one contact fixing portion.   The sensor-equipped wheel bearing according to claim 1 or 2, wherein the stationary member is an outer member.   The sensor-equipped wheel according to any one of claims 1 to 3, wherein the strain generating member of the sensor unit has a notch, and the sensor is provided around the notch. Bearings.   In any one of Claims 1 thru | or 4, The flange for a 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 a circumferential portion provided with each bolt hole protrudes to the outer diameter side than the other portion, and the sensor unit is arranged at the center between the adjacent projecting pieces. Bearing with sensor wheel.   6. The sensor-equipped wheel according to claim 1, wherein one of the sensor units is provided on an upper surface portion of an outer diameter surface of the outer member with respect to a tire ground contact surface. bearing.   7. The vehicle wheel according to claim 1, wherein at least one of an absolute value of the output signal of the sensor, an average value of the output signal, and an amplitude of the output signal is used. A sensor-equipped wheel bearing comprising an estimation means for estimating a load acting on the bearing.   The sensor-equipped wheel bearing according to any one of claims 1 to 7, wherein the sensor unit detects a load in a vertical direction acting on the wheel bearing.

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