JP2010139303A - Sensor-equipped bearing for wheel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sensor-equipped bearing for wheel capable of precisely and stably detecting a load acting on the bearing for wheel or tire ground contact surface without being affected by variation of external environments. <P>SOLUTION: A sensor-equipped bearing for wheel is formed by arranging rolling bodies 5 between opposed double-row rolling surfaces 3, 4 of an outer member 1 and an inner member 2. A sensor unit 20 is provided at a circumferential surface of a member at a fixed side from among the outer member 1 or the inner member 2. The sensor unit 20 includes a strain generation member 21 in contact with and fixed to the circumferential surface of the member at the fixed side, a strain sensor 22 mounted to the strain generation member 21 and detecting strain in the strain generation member 21, and a temperature sensor 28 mounted to the strain generation member 21 and detecting the temperature of a part where the strain sensor is mounted. The sensor unit 20 is shielded from ambient air by a heat insulating material 29. An estimation means 30 correcting a sensor output signal of the sensor unit 20 by the output of the temperature sensor 28 and estimating a load acting on the bearing for wheel or the tire from the corrected signal is provided. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

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

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

  Furthermore, a sensor unit comprising a strain generating member and a strain sensor attached to the strain generating member is attached to a fixed ring of the bearing, and the strain generating member has at least two contact fixing portions with respect to the fixed ring, A sensor-equipped wheel bearing has been proposed that has at least one notch portion between adjacent contact fixing portions, and the strain sensor is disposed in the notch portion (for example, Patent Document 3).

According to the sensor-equipped wheel bearing disclosed in Patent Document 3, when a load is applied to the rotating wheel as the vehicle travels, the fixed wheel is deformed via the rolling elements, and this deformation causes distortion of the sensor unit. The strain sensor provided in the sensor unit detects the strain of the sensor unit. If the relationship between strain and load is obtained in advance through experiments and simulations, the load applied to the wheel can be detected from the output of the strain sensor.
JP 2002-098138 A Special table 2003-530565 gazette JP 2007-57299 A

In the technique disclosed in Patent Document 1, distortion generated by deformation of the flange portion of the fixed ring is detected. However, the deformation of the flange portion of the fixed ring involves slipping when a force exceeding the static friction force is applied between the flange surface and the knuckle surface, so that hysteresis is generated in the output signal when 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, hysteresis occurs when an attempt is made to estimate the load at the portion where this deformation occurs. When hysteresis occurs, the detection resolution decreases.
In addition, when a strain gauge is attached to the outer ring as in Patent Document 2, there is a problem in assemblability.

  Further, not only in the examples of Patent Document 1 and Patent Document 2, but also in the wheel bearing with sensor disclosed in Patent Document 3, since the strain sensor is provided on the fixed ring of the wheel bearing, the temperature changes. The output signal of the strain sensor fluctuates. That is, for example, in the sensor-equipped wheel bearing disclosed in Patent Document 3, when the temperature of the wheel bearing changes due to heat generated by the rotation of the bearing or the surrounding environment, the wire between the fixed ring and the sensor unit does not change even if the load changes. The output signal of the strain sensor varies due to the difference in expansion coefficient. In this sensor-equipped wheel bearing, a plurality of sensor units are attached to the fixed wheel, and each sensor unit takes an average value of the sensor outputs as an output signal, and estimates the load from the sum or difference of the plurality of output signals. In such a case, the load detection error increases due to the influence of the output fluctuation due to the temperature change.

  In order to reduce the error of the estimated load due to the temperature change described above, for example, in the sensor-equipped wheel bearing disclosed in Patent Document 3, a temperature sensor is installed on the sensor unit, and the above linear expansion is performed by the output of the temperature sensor. It is conceivable to correct the strain sensor output signal due to the difference in the rate, etc., and to correct the temperature characteristics of the strain sensor itself.

  However, if the sensor unit and the outside air are not sufficiently insulated, the heat radiation resistance will change depending on the outside air condition and the sensor surroundings (air volume, moisture adhesion, etc.). And the temperature detected by the temperature sensor on the sensor unit will be different. As a result, a difference occurs between the actual temperature expansion state and the correction value calculated from the detected temperature, and an error occurs in the finally obtained load estimated value.

  An object of the present invention is to provide a sensor-equipped wheel bearing capable of stably detecting a load acting on a wheel bearing or a tire ground contact surface with high accuracy without being affected by fluctuations in the external environment.

The sensor-equipped wheel bearing according to the present invention includes an outer member having a double-row rolling surface formed on the inner periphery, an inner member having a rolling surface opposed to the rolling surface formed on the outer periphery, A wheel bearing comprising a double row rolling element interposed between opposing rolling surfaces of the member and rotatably supporting the wheel with respect to the vehicle body, wherein the fixed side member of the outer member and the inner member A sensor unit is provided on the peripheral surface of the strain generating member, and the sensor unit is a strain generating member having two or more contact fixing parts fixed in contact with the peripheral surface of the fixed side member, and is attached to the strain generating member to be distorted. One or more strain sensors for detecting strain of the generating member, and a temperature sensor attached to the strain generating member for detecting the temperature of the strain sensor installation portion, the sensor unit and outside air around the sensor unit Insulating material between A sensor output signal of the serial sensor unit is corrected by the output of the temperature sensor, characterized in that a estimating means for estimating a load applied from the correction signal on the wheel support bearing or tire. The stationary member may be an outward member, for example. The heat insulating material is preferably provided so as to block the sensor unit from outside air. However, when a separate member, for example, a protective cover as described later is provided, the sensor unit is composed of a separate member such as a protective cover and the heat insulating material. May be blocked from outside air.
When a load acts between the wheel bearing or the tire of the wheel and the road surface, the load is also applied to the stationary side member (for example, the outer member) of the wheel bearing to cause deformation. Since the contact fixing portion of the strain generating member in the sensor unit is fixed in contact with the outer member, the strain of the outer member is transmitted to the strain generating member in an enlarged manner, and the strain is detected with high sensitivity by the strain sensor. Hysteresis generated in the output signal is also reduced, and the load can be estimated with high accuracy.
In addition, a temperature sensor for detecting the temperature of the strain sensor installation portion is attached to the strain generating member of the sensor unit, and the estimation means corrects the output signal of the strain sensor with the output of the temperature sensor, and the wheel bearing is determined from the corrected signal. Alternatively, the load applied to the tire is estimated, so when the temperature of the wheel bearing changes due to the heat generated by the rotation of the bearing or the surrounding environment, distortion occurs due to the difference in linear expansion coefficient between the outer member and the sensor unit. Variations in the sensor output signal can be corrected.
In this case, if the heat insulation between the sensor unit and the outside air is insufficient, the heat dissipation resistance changes depending on the outside air state and the surrounding state of the strain sensor (air volume, presence or absence of moisture adhesion, etc.). And the temperature detected by the temperature sensor deviate from each other, the correction value calculated by the correction by the estimation means and the actual temperature expansion state deviate, and an error occurs in the load estimated by the estimation means. . In this sensor-equipped wheel bearing, heat-insulating material is interposed between the sensor unit and the surrounding outside air, so that it is not affected by the state of the outside air or adhesion of moisture, etc. The load acting on the wheel bearing and the tire ground contact surface can be detected with high accuracy and stability.

  In the present invention, three or more sensor units may be provided, and the estimation means may estimate a radial load and an axial load applied to a wheel bearing or a tire from sensor output signals of these sensor units.

  In the present invention, four sensor units are provided, and these sensor units are arranged in an up-down position and a left-right position with respect to the tire ground contact surface. You may arrange | position to a surface part so that a 90 degree phase difference may be made | formed in the circumferential direction. In this configuration, the load can be accurately estimated under any load condition. That is, when the load in a certain direction increases, the part where the rolling element and the rolling surface are in contact with each other and the part that is not in contact appear with a phase difference of 180 degrees. If installed, the load applied to the stationary member is always transmitted to one of the sensor units via the rolling elements, and the load can be detected by the strain sensor.

  As the heat insulating material, resin or rubber can be used. The heat insulating material is particularly preferably a foamed material such as a foamed resin. According to these heat insulating materials, a heat insulating effect can be effectively obtained, and the process of providing the heat insulating material is simple.

  In this invention, the said heat insulation material may be a coating layer which coat | covers the exposed surface with respect to the external air of the said sensor unit. When it is a coating layer, a heat insulating material can be easily provided by a process such as molding.

In this invention, the sensor unit, the signal processing IC for processing the output signal of the sensor, and the wiring system of the sensor and the signal processing IC are connected to the peripheral protective surface of the annular member. It arrange | positions inside and this protective cover has an opening part which exposes a sensor unit to the arrangement | positioning part of a sensor unit, and you may seal this opening part with the said heat insulation material.
In this configuration, the protective cover protects the sensor unit's sensor and wiring system against contact with foreign objects such as stepping stones, and minimizes the sensor unit from the influence of the external environment such as outside air temperature and water. Can be suppressed.

In this invention, the sensor unit may be covered with a protective cover, and the inside of the protective cover may be filled with the heat insulating material that blocks the sensor unit from outside air. The protective cover in this case may cover each sensor unit individually, or may cover a plurality of sensor units collectively.
When the protective cover is provided in this way and the inside thereof is filled with a heat insulating material, the protective cover protects the sensor unit against contact with foreign matters such as stepping stones and the like, and can insulate the sensor unit from the outside air. In addition, since the heat insulating material is provided in the protective cover, the heat insulating material can be easily attached.

  In this invention, the sensor unit may be covered with a protective cover, and an air layer may be sealed inside the protective cover as the heat insulating material that shields the sensor unit from outside air. The air layer has a high thermal insulation effect, and it is covered with a protective cover to make the inside an air layer, thereby protecting both the sensor unit against foreign matter contact and blocking the sensor unit from the outside environment such as the outside air temperature and water droplets. It can be obtained with a simple configuration in which only a protective cover is provided.

  In this invention, the protective cover may be annular and attached to the peripheral surface of the fixed side member concentrically with the fixed side member. When the protective cover is annular, it is easy to attach the protective cover to the stationary member, and a single protective cover can cover a plurality of sensor units arranged in the circumferential direction.

  In the present invention, the protective cover may be made of stainless steel. Stainless steel is desirable as a material for the protective cover from the viewpoint of providing the protective cover with sufficient strength and corrosion resistance and increasing the effect of blocking the sensor unit from the outside air.

  In this invention, you may cover the surface of the said sensor unit, and the installation part periphery of the said sensor unit of the surrounding surface of the said stationary-side member with a material with high heat conductivity. A material having a high thermal conductivity is more preferable as the thermal conductivity is higher, but any material having a higher thermal conductivity than the average thermal conductivity of the resin material may be used. Thus, when the surface of the sensor unit and the periphery of the sensor unit installation portion on the peripheral surface of the fixed member are covered with a material having high thermal conductivity, the temperature difference between the peripheral surface of the fixed member and the sensor unit is reduced, The deviation between the temperature of the stationary member and the temperature detected by the temperature sensor can be further reduced, and the load acting on the wheel bearing and the tire ground contact surface can be detected stably with higher accuracy.

  The sensor-equipped wheel bearing according to the present invention includes an outer member having a double-row rolling surface formed on the inner periphery, an inner member having a rolling surface opposed to the rolling surface formed on the outer periphery, A wheel bearing comprising a double row rolling element interposed between opposing rolling surfaces of the member and rotatably supporting the wheel with respect to the vehicle body, wherein the fixed side member of the outer member and the inner member A sensor unit is provided on the peripheral surface of the strain generating member, and the sensor unit is a strain generating member having two or more contact fixing parts fixed in contact with the peripheral surface of the fixed side member, and is attached to the strain generating member to be distorted. One or more strain sensors for detecting strain of the generating member, and a temperature sensor attached to the strain generating member for detecting the temperature of the strain sensor installation portion, the sensor unit and outside air around the sensor unit Insulating material between Since the sensor output signal of the sensor unit is corrected with the output of the temperature sensor and the estimation means for estimating the load applied to the wheel bearing or tire from the corrected signal is provided, it is not affected by fluctuations in the external environment, The load acting on the wheel bearing and the tire ground contact surface can be detected stably with high accuracy.

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

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

  Three or more sensor units 20 are provided on the outer diameter surface of the outer member 1 that is a stationary member. Here, the four sensor units 20 are arranged in the circumferential direction 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. Are provided so as to form a phase difference of 90 degrees. Here, the two sensor units 20 constituting one pair of sensor units are provided at two locations on the outer diameter surface of the outer member 1 that is located above the tire ground contact surface, the upper surface portion and the lower surface portion. Yes. In addition, two sensor units 20 constituting another pair of sensor unit pairs are provided at two locations, the right surface portion and the left surface portion, on the outer diameter surface of the outer member 1 that are front and rear positions with respect to the tire ground contact surface. ing.

  3 and 4, the sensor unit 20 includes a strain generating member 21 and a strain that is attached to the strain generating member 21 and detects the strain of the strain generating member 21. The sensor 22 includes a temperature sensor 28 that is attached to the strain generating member 21 and detects the temperature of the installation portion of the strain sensor 22. The strain generating member 21 is made of an elastically deformable metal thin plate material of 2 mm or less such as a steel material, has a planar shape in a strip shape, and has notches 21b on both sides of the center. Further, the strain generating member 21 has two contact fixing portions 21a that are fixed to the outer diameter surface of the outer member 1 through spacers 23 at both ends. The strain sensor 22 is affixed to a location where the strain increases with respect to the load in each direction on the strain generating member 21. Here, as the location, a central portion sandwiched between the notch portions 21b on both sides is selected on the outer surface side of the strain generating member 21, and the strain sensor 22 measures the circumferential strain around the notch portion 21b. To detect. 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 plastic deformation occurs, the deformation of the outer member 1 is not transmitted to the sensor unit 20 and affects the measurement of strain. Here, the “assumed maximum force” is the maximum in the range in which the normal function of the bearing excluding the sensor system can be restored when an abnormal force is applied to the bearing. It is power.

  The sensor unit 20 is arranged such that the two contact fixing portions 21a of the strain generating member 21 are located at positions having the same dimension in the axial direction of the outer member 1 and being spaced apart from each other in the circumferential direction. These contact fixing portions 21 a are respectively fixed to the outer diameter surface of the outer member 1 by bolts 24 through spacers 23. Thereby, the strain sensor 22 of the sensor unit 20 detects the strain in the outer member circumferential direction around the notch 21 b of the strain generating member 21. Each bolt 24 is inserted into a bolt insertion hole 26 of the spacer 23 from a bolt insertion hole 25 penetrating in the radial direction provided in the contact fixing portion 21 a, and a screw hole 27 provided in the outer peripheral portion of the outer member 1. Screwed on. In this way, by fixing the contact fixing portion 21a to the outer diameter surface of the outer member 1 via the spacer 23, the central portion having the notch portion 21b in the strain generating member 21 having a thin plate shape is the outer member 1. It becomes a state away from the outer diameter surface of the, and distortion deformation around the notch 21b becomes easy.

  As the axial position where the contact fixing portion 21a is disposed, an axial position that is the periphery of the rolling surface 3 of the outboard side row of the outer member 1 is selected here. Here, the periphery of the rolling surface 3 of the outboard side row is a range from the intermediate position of the rolling surface 3 of the inboard side row and the outboard side row to the formation portion of the rolling surface 3 of the outboard side row. It is. In order to stably fix the sensor unit 20 to the outer diameter surface of the outer member 1, a flat portion 1 b is formed at a location where the spacer 23 is contacted and fixed on the outer diameter surface of the outer member 1.

  Various 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 surface of the sensor unit 20 is covered with a heat insulating material 29, thereby blocking the sensor unit 20 from the outside air. The heat insulating material 29 is provided as a covering layer that covers the sensor unit 20 and covers the entire surface of the sensor unit 20 except the contact surface with respect to the outer member 1. The heat insulating material 29 here is a material having a low thermal conductivity such as urethane foam, foamed resin molding material, urethane-based resin molding material, or rubber.

  The strain sensor 22 and the temperature sensor 28 of the sensor unit 20 are connected to the estimation unit 30. The estimation means 30 uses the output signal of the strain sensor 22 to determine the force acting on the wheel bearing or between the wheel and the road surface (tire contact surface) (vertical load Fz, load Fx serving as driving force or braking force, axial load Fy). ) And temperature correction means 31 for correcting the output signal of the strain sensor 22 with the output of the temperature sensor 28. The temperature correction unit 31 corrects the output signal of the strain sensor 22 in accordance with, for example, an arithmetic expression or a table (not shown) that sets the relationship between the temperature and the output value that is the correction value or the correction result. In the estimating means 30, the vertical load Fz that is a radial load and the load Fx that is a driving force or a braking force and an axial direction that is a cornering force are obtained from the output signal of the strain sensor 22 corrected by the temperature correcting means 31. Estimate the load Fy.

  The estimation unit 30 includes a relationship setting unit (not shown) in which the relationship between the acting force and the correction value of the output signal of the strain sensor 22 obtained by the temperature correction unit 31 is set by an arithmetic expression or a table. An action force value is output from the input correction value 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. Since the two contact fixing portions 21a of the strain generating member 21 in the sensor unit 20 are fixed in contact with the outer diameter surface of the outer member 1, the strain of the outer member 1 is transmitted to the strain generating member 21 in an enlarged manner, The distortion is detected by the distortion sensor 22 with high sensitivity, the hysteresis generated in the output signal is also reduced, and the load can be estimated with high accuracy.

  In addition, a temperature sensor 28 for detecting the temperature of the installation portion of the strain sensor 22 is attached to the strain generating member 21 of the sensor unit 20, and the estimation means 30 causes the temperature correction means 31 to output the output signal of the strain sensor 22 from the temperature sensor 28. Since the output is corrected and the load applied to the wheel bearing or tire is estimated from the corrected signal, when the temperature of the wheel bearing changes due to heat generated by the rotation of the bearing or the surrounding environment, the outer member Variations in the output signal of the strain sensor 22 due to the difference in linear expansion coefficient between the sensor unit 20 and the sensor unit 20 can be corrected. In this case, if the heat insulation between the sensor unit 20 and the outside air is insufficient, the heat radiation resistance changes depending on the state of the outside air and the surrounding state of the strain sensor 22 (air volume, presence / absence of moisture adhesion, etc.). 1 and the temperature detected by the temperature sensor 28 are shifted, the correction value calculated by the temperature correction means 31 and the actual temperature expansion state are shifted, and the load finally estimated by the estimation means 30 An error occurs. In this sensor-equipped wheel bearing, since the sensor unit 20 is shielded from the outside air by the heat insulating material 29, the influence of the external environment described above can be suppressed to the minimum, and acts on the wheel bearing and the tire ground contact surface. The load can be detected with high accuracy and stability.

In the above description, the case where the acting force between the wheel tire and the road surface is detected is shown. However, not only the acting force between the wheel tire and the road surface but also the force acting on the wheel bearing (for example, the preload amount) is detected. It is also good.
By using the detected load obtained from the sensor-equipped wheel bearing for vehicle control of the automobile, it is possible to contribute to stable running of the automobile. In addition, when this sensor-equipped wheel bearing is used, a load sensor can be installed in a compact vehicle, the mass productivity can be improved, and the cost can be reduced.

  Further, in this embodiment, four sensor units 20 are provided, and these sensor units 20 are arranged on the upper surface portion, the lower surface portion, and the outer diameter surface of the outer member 1 that are in the vertical position and the horizontal position with respect to the tire ground contact surface. Since the right surface portion and the left surface portion are arranged so as to have a phase difference of 90 degrees in the circumferential direction, the load can be accurately estimated under any load condition. That is, when a load in a certain direction increases, a portion where the rolling element 5 and the rolling surfaces 3 and 4 are in contact with each other and a portion which is not in contact appear with a phase difference of 180 degrees. Is installed with a phase difference of 180 degrees, a load applied to the outer member 1 is always transmitted to one of the sensor units 20 via the rolling elements 5, and the load can be detected by the strain sensor 22.

  5 to 13 show another embodiment of the present invention. The sensor-equipped wheel bearing of this embodiment is obtained by attaching the sensor unit 20 to an annular protective cover 37. As shown in FIG. 10, the sensor unit 20 includes a strain generating member 21, a strain sensor 22 that is attached to the strain generating member 21 and detects the strain of the strain generating member 21, and is attached to the strain generating member 21 to be distorted. The temperature sensor 28 detects the temperature of the sensor installation part. Insertion holes 25 for bolts 24 (FIG. 6) for fixing the sensor unit 20 to the outer diameter surface of the outer member 1 are provided at two positions of the strain generating member 21 that are separated in the longitudinal direction across the strain sensor 22. It has been.

  Also in this embodiment, there are four sensor units 20, and electronic components such as a signal processing IC 35 for processing the output signals of these strain sensors 22 and a signal cable 36 (FIG. 10) for taking out the processed output signals to the outside of the bearing. 8A and 8B are arranged inside an annular protective cover 37 shown in front and side views in FIGS. 8A and 8B, and circles shown in front and side views in FIGS. 11A and 11B. An annular sensor assembly 38 is constructed. FIG. 10 is a development view of the electronic component disposed inside the protective cover 37. A signal cable 36 is wired between the sensor units 20 along the groove 39 of the protective cover 37, and a signal processing IC 35 is disposed in the middle of the signal cable 36. The lead-out portion 36 a of the signal cable 36 toward the vehicle body is drawn out from the protective cover 37 to one side of the protective cover 37. The material of the protective cover 37 may be plastic or rubber, or may be made of metal such as stainless steel.

  As shown in FIGS. 9A and 9B showing the cross-sectional view taken along arrows IXa-IXa and IXb-IXb in FIGS. There are provided groove portions 39 extending in the direction, and openings 40 penetrating in the radial direction are provided at four locations where the sensor units 20 are arranged in the circumferential direction. On both side edges along the circumferential direction on the inner diameter side of these openings 40, planar engagement step portions 40a with which the strain generating members 21 of the sensor unit 20 are engaged are provided. Accordingly, as shown in FIGS. 12A and 12B showing the XIIa-XIIa arrow cross-sectional view and the XIIb-XIIb arrow cross-sectional view of FIGS. 11A and 11B, the opening 40 of the protective cover 37. Further, each sensor unit 20 is installed with its distortion generating member 21 exposed to the inner diameter side.

  The annular sensor assembly 38 can be divided into two at the center as shown in FIGS. Specifically, an annular protective cover 37 is formed by connecting one end of each of the two divided bodies 37 </ b> A and 37 </ b> B with a hinge 41 so that the two semicircular arcs of the sensor assembly 38 can be connected via the hinge 41. The part can be opened and closed. The maximum value of the opening dimension W in the opened state of the sensor assembly 38 is set to be larger than the outer diameter dimension D (FIG. 6) of the outer member 1. As a result, the sensor assembly 38 can be attached to the outer diameter surface of the outer member 1 with the opening dimension W being maximized.

  FIG. 6 shows a cross-sectional view of the outer member 1 viewed from the inboard side. The axial position of the outer diameter surface of the outer member 1 to which the sensor assembly 38 is attached is a cylindrical grinding surface over the entire circumference, and the strain generating member 21 of the sensor unit 20 contacts the cylindrical grinding surface 4. The portions, that is, the upper surface portion, the lower surface portion, the right surface portion, and the left surface portion are flat portions 1b as shown in FIG. Thereby, the distortion generating member 21 of each sensor unit 20 can be reliably brought into contact with the flat portion 1b. Each flat portion 1b is provided with a screw hole 27 (FIG. 6) that matches the bolt insertion hole 25 of the strain generating member 21. Thus, after the sensor assembly 38 is assembled on the outer diameter surface of the outer member 1, the bolt 24 (FIG. 6) inserted into the bolt insertion hole 25 of the strain generating member 21 is screwed into the screw hole 27. Thus, the sensor unit 20 is fixed to the outer diameter surface of the outer member 1, and at the same time, the entire sensor assembly 38 is also fixed. An intermediate portion sandwiched between the two screw holes 27 in the flat portion 1b is provided with a groove 1c (FIG. 7) extending in the axial direction. Thereby, since the intermediate part in which the notch part 21b in the distortion generating member 21 is located is separated from the flat part 1b, distortion deformation around the notch part 21b is facilitated. The four sensor units 20 are provided at positions where the respective strain sensors 22 have the same dimensions with respect to the axial direction of the outer member 1.

  FIG. 7 is an enlarged view of the mounting portion of the sensor assembly 38 of the outer member 1 in FIG. As shown in the figure, after the sensor assembly 38 is attached to the outer diameter surface of the outer member 1, the exposed portion of the sensor unit 38 from the protective cover 37 of the sensor unit 20 is covered with a heat insulating material 29. Thereby, the sensor unit 20 is shielded from the outside air by the heat insulating material 29. In addition, exposed portions of the other electronic components (signal processing IC 35 and signal cable 36) of the sensor assembly 38 from the protective cover 37 are also sealed with a molding material (not shown). Specifically, the groove 39 of the protective cover 37 is filled with a molding material over the entire circumference, and the exposed portion of the electronic component is sealed. The molding material may be the same material as the heat insulating material 29. From the viewpoint of providing the protective cover 37 with sufficient strength and corrosion resistance and improving the effect of blocking the sensor unit 20 from the outside air, the material of the protective cover 37 is preferably stainless steel.

  The strain sensor 22 and the temperature sensor 28 of the sensor unit 20 are connected to the signal processing IC 35. The signal processing IC 35 generates forces (vertical load Fz, driving force Fx, axial load Fy) acting between the wheel bearing and the wheel and the road surface (tire contact surface) according to the output signal of the strain sensor 22. The estimation means is an estimation means (corresponding to the estimation means 30 in the embodiment of FIGS. 1 to 4), and includes a signal processing circuit, a correction circuit, and the like. The correction circuit includes the temperature correction means 31 in the embodiment of FIGS. Other configurations are the same as those in the embodiment of FIGS.

  Also in this embodiment, the output signal of the strain sensor 22 is corrected by the output of the temperature sensor 28 by the signal processing IC 35 that is a load estimating means, and the load applied to the wheel bearing or tire from the corrected signal is calculated. Although it is estimated, since the sensor unit 20 is shielded from the outside air by the heat insulating material 29, the deviation between the temperature of the outer member 1 and the temperature detected by the temperature sensor 28 is reduced, and the influence of the external environment is reduced. The load acting on the wheel bearing and the tire ground contact surface can be detected stably with high accuracy.

  In this embodiment, an electronic component including a plurality of sensor units 20, a signal processing IC 35 that processes the output signal of the strain sensor 22, and a signal cable 36 that extracts the processed output signal to the outside of the bearing, Since the annular sensor cover 38 is arranged inside the annular protective cover 37 and the sensor assembly 38 is attached to the outer diameter surface of the outer member 1 concentrically with the outer member 1, the external environment As a result, it is possible to prevent the electronic components including the sensor unit 20 from being broken (damage due to stepping stones, corrosion due to muddy water, salt water, etc.), and the load can be accurately detected over a long period of time. In addition, wiring processing of the signal cable 36 and assembly of the strain sensor 22 are facilitated. Further, since the sensor unit 20 is covered with the protective cover 37, the protection of the sensor unit 20 and the heat insulation with the outside air can be realized with a compact configuration.

  In this embodiment, since the sensor assembly 38 can be divided into two at the center, it is easy to attach the outer member 1 which is a stationary member to the outer diameter surface, and the assemblability is improved.

  Further, in this embodiment, the strain generating member 21 of the sensor unit 20 is directly fixed to the outer diameter surface of the outer member 1 that is a fixed member with the bolt 24, so that the sensor unit 20 can be firmly fixed. Even when a load is applied, the fixed portion does not slip, and the detection accuracy can be improved accordingly. Further, by fixing the sensor unit 20 to the outer member 1 with the bolts 24, the sensor assembly 38 can be attached to the outer member 1 at the same time, so that the assemblability is further improved.

  If the axial dimension of the sensor unit 20 fixed to the outer diameter surface of the outer member 1 that is a fixed side member is different, the strain transmitted from the outer diameter surface of the outer member 1 to the strain generating member 21 is also different. In this embodiment, the sensor units 20 are provided at positions where the respective strain sensors 22 have the same dimensions with respect to the axial direction of the outer member 1, so that a plurality of protective units 37 that circulate around the axial position are provided. The electronic parts including the sensor unit 20 can be protected, and the protective cover 37 can be made compact.

  FIG. 14 shows still another embodiment of the present invention. In the sensor-equipped wheel bearing, in the embodiment shown in FIGS. 5 to 13, the protective cover 37 </ b> A is provided as a dedicated component that covers the sensor unit 20 without being used as an attachment member of the sensor unit 20. In this example, the protective cover 37A is an annular part having a groove shape or a U-shaped cross-section with an opening on the outer member 1 side, and covers the sensor unit 20 and is fitted to the outer periphery of the outer member. It is installed. In the illustrated example, the protective cover 37 </ b> A has a groove-shaped cross-sectional shape including an outer peripheral wall portion and a pair of side wall portions. A heat insulating material 29 that shields the sensor unit 20 from the outside air fills the entire interior of the protective cover 37A. The material of the protective cover 37A is preferably stainless steel, like the protective cover 37 shown in FIGS. Other configurations are the same as those of the embodiment of FIGS.

  FIG. 15 shows still another embodiment of the present invention. In this sensor-equipped wheel bearing, in the embodiment of FIG. 14, the heat insulating material 29 that blocks the sensor unit 20 from the outside air is not filled in the entire interior of the protective cover 37A, and only the surface of the sensor unit 20 is covered. Provided. An air layer is formed between the surface of the sensor unit 20 and the inner surface of the outer peripheral wall portion of the protective cover 37A. This air layer functions as a heat insulating material, and the heat insulating material 29 and the air layer constitute a double heat insulating material layer. Other configurations are the same as those in the embodiment of FIG.

  FIG. 16 shows still another embodiment of the present invention. In this sensor-equipped wheel bearing, in the embodiment of FIG. 14, the thermal conductivity of the surface of the sensor unit 20 and the periphery of the sensor unit 20 on the outer diameter surface of the outer member 1 within the protective cover 37 </ b> A. It is covered with a high material 42 and the space above it is filled with a heat insulating material 29. As the material 42 having a high thermal conductivity, a material having a high thermal conductivity is preferable. However, it is sufficient that the material has an average thermal conductivity higher than that of the resin material, and a thermal conductive paste, silicon rubber, or the like is used. The heat insulating material 29 is provided along the inner surface of the outer peripheral wall portion of the protective cover 37A, and an air layer is formed between the heat insulating material 29 and the material 42 having a high thermal conductivity. This air layer functions as a heat insulating material, and the heat insulating material 29 and the air layer constitute a double heat insulating material layer. Other configurations are the same as those in the embodiment of FIG.

  In this embodiment, the surface of the sensor unit 20 and the periphery of the installation portion of the sensor unit 20 on the outer diameter surface of the outer member 1 are covered with the material 42 having high thermal conductivity, and the outer diameter surface of the outer member 1 and the sensor are covered. Since the temperature difference of the unit 20 is reduced, the deviation between the temperature of the outer member 1 and the temperature detected by the temperature sensor 28 can be further reduced, and the load acting on the wheel bearing and the tire ground contact surface. Can be detected stably with higher accuracy.

  FIG. 17 shows still another embodiment of the present invention. In this sensor-equipped wheel bearing, in the embodiment of FIG. 14, the thermal conductivity of the surface of the sensor unit 20 and the periphery of the sensor unit 20 on the outer diameter surface of the outer member 1 within the protective cover 37 </ b> A. The air layer 43 is substituted for the heat insulating material 29 by covering it with the high material 42 and making the space above it a sealed space for the air layer 43. Other configurations are the same as those of the embodiment of FIG.

  18 to 20 show still another embodiment of the present invention. In this sensor-equipped wheel bearing, in the embodiment shown in FIGS. 5 to 13, the annular sensor assembly 38 is provided on the outer diameter surface of the outer member 1 which is a fixed member of the bearing via a seal member 50. It is attached concentrically with the outer member 1. As shown in part in an enlarged cross-sectional view in FIG. 20, the seal member 50 includes a ring-shaped cored bar 51 along the inner diameter surface of the protective cover 37, and the outer circumference of both side edges of the cored bar 51 outside the inner diameter surface. It consists of a pair of ring-shaped elastic bodies 52 joined over the radial surface. A sensor unit exposure opening 53 (FIG. 19) penetrating in the radial direction is provided at each position in the circumferential direction of the seal member 50 facing the arrangement portion of the sensor unit 20 in the sensor assembly 38. As a result, the sensor unit 20 is attached to the outer diameter of the outer member 1 from the sensor unit exposure opening 53 of the seal member 50 in a state where the sensor assembly 38 is attached to the outer diameter surface of the outer member 1 via the seal member 50. The surface can be contacted.

  The metal core 51 of the seal member 50 is made of a press-molded product of corrosion-resistant steel, and both side edges to which the ring-shaped elastic body 52 is joined are diameter-expanded bent portions 51a that expand to the outer diameter side. The ring-shaped elastic body 52 has a U-shaped cross-section having a groove portion 52 a along the circumferential direction on the inward side surface, and the groove portion 52 a is press-fitted into the diameter-enlarged bent portion 51 a of the core metal 51, thereby Ring-shaped elastic bodies 52 are joined to both side edges. With such a joining structure, the ring-shaped elastic body 52 can be easily and reliably joined to both side edges of the cored bar 51 without using an adhesive or the like.

  In addition, on both sides of the inner diameter surface of the protective cover 37 of the annular sensor assembly 38, an inner diameter side groove 39B is formed to be in close contact with the ring-shaped elastic body 52 of the seal member 50 as shown in FIG. . The sensor assembly 38 is attached to the seal member 50 after the seal member 50 is press-fitted onto the outer diameter surface of the outer member 1. Other configurations are the same as those of the embodiment of FIGS.

  In this embodiment, the seal member 50 is a ring-shaped cored bar 51 along the inner diameter surface of the protective cover 37 and a pair of ring-shaped members joined to the entire circumference of both side edges of the cored bar 51 from the inner diameter surface to the outer diameter surface. Since the elastic body 52 is used, the elastic bodies 52 on both side edges of the seal member 50 are sandwiched between the outer diameter surface of the outer member 1 and the inner diameter surface of the protective cover 37, so And the outside can be completely blocked by the elastic body 52, and the sealing effect of the seal member 50 can be improved.

  In each of the above embodiments, the case where the outer member 1 is a fixed side member has been described. However, the present invention can also be applied to a wheel bearing in which the inner member is a fixed side member. The unit 20 or the sensor assembly 38 is provided on the peripheral surface that is the inner periphery of the inner member.

  In this embodiment, the case where the present invention is applied to a third generation type wheel bearing has been described. However, the present invention relates to a first or second generation type wheel bearing in which the bearing portion and the hub are independent parts. In addition, the present invention can also be applied to a fourth generation type wheel bearing in which a part of the inner member is composed of an outer ring of a constant velocity joint. Further, this sensor-equipped wheel bearing can be applied to a wheel bearing for a driven wheel, and can also be applied to a tapered roller type wheel bearing of each generation type. Further, the present invention can be applied to a wheel bearing in which the outer member is a rotation side member. In that case, a sensor unit or a sensor assembly is provided on the outer periphery of the inner member.

It is a figure showing combining the sectional view of the wheel bearing with a sensor concerning one embodiment of this invention, and the block diagram of the conceptual composition of the detection system. It is the front view which looked at the outer member of the wheel bearing with a sensor from the outboard side. It is an enlarged plan view of a sensor unit in the wheel bearing with sensor. FIG. 4 is a cross-sectional view taken along arrow IV-IV in FIG. 3. It is sectional drawing of the bearing for wheels with a sensor concerning other embodiment of this invention. It is VI-VI arrow sectional drawing in FIG. It is an expanded sectional view of the sensor assembly installation part in the outward member of FIG. (A) is a front view of an annular | circular shaped protective cover, (B) is the same side view. (A) is a cross-sectional view taken along the line IXa-IXa in FIG. 8 (A), and (B) is a cross-sectional view taken along the line IXb-IXb in FIG. 8 (B). It is an expanded view of the electronic component installed in a sensor assembly. (A) is a front view of the sensor assembly, and (B) is a side view of the sensor assembly. (A) is XIIa-XIIa arrow sectional drawing in FIG. 11 (A), (B) is XIIb-XIIb arrow sectional drawing in FIG. 11 (B). (A) is a front view which shows the closed state of a sensor assembly, (B) is a front view which shows the open state of the sensor assembly. It is a partially expanded sectional view of the bearing for wheels with a sensor concerning other embodiment of this invention. It is a partially expanded sectional view of the bearing for wheels with a sensor concerning other embodiment of this invention. It is a partially expanded sectional view of the bearing for wheels with a sensor concerning other embodiment of this invention. It is a partially expanded sectional view of the bearing for wheels with a sensor concerning other embodiment of this invention. It is sectional drawing of the bearing for wheels with a sensor concerning further another embodiment of this invention. It is an expanded sectional view of the circumferential position where the sensor unit is arranged in the axial position where the sensor assembly of the outer member of the wheel bearing with sensor is installed. It is a partial expanded sectional view of a sealing member.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Outer member 2 ... Inner member 3, 4 ... Rolling surface 5 ... Rolling body 20 ... Sensor unit 21 ... Strain generating member 21a ... Contact fixing | fixed part 22 ... Strain sensor 28 ... Temperature sensor 29 ... Thermal insulation material 30 ... Estimation Means 31 ... Temperature correction means 35 ... Signal processing IC
37, 37A ... protective cover 42 ... material with high thermal conductivity 43 ... air layer (heat insulating material)

Claims (13)

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 sensor unit is provided on a peripheral surface of the fixed side member of the outer member and the inner member, and the sensor unit has two or more contact fixing portions fixed in contact with the peripheral surface of the fixed side member. A strain generating member, one or more strain sensors attached to the strain generating member to detect strain of the strain generating member, and a temperature sensor attached to the strain generating member to detect the temperature of the strain sensor installation portion. A heat insulating material is interposed between the sensor unit and the ambient air around the sensor unit, the sensor output signal of the sensor unit is corrected by the output of the temperature sensor, and the wheel bearing or tire is corrected from the corrected signal. A bearing for a wheel with a sensor, characterized in that an estimation means for estimating a load applied to the vehicle is provided.   The sensor-equipped wheel bearing according to claim 1, wherein the fixed-side member is the outer member.   3. The sensor unit according to claim 1, wherein three or more sensor units are provided, and the estimation means estimates a radial load and an axial load applied to a wheel bearing or a tire from sensor output signals of these sensor units. Wheel bearing with sensor.   4. The upper surface of the peripheral surface of the fixed side member according to claim 1, wherein the four sensor units are provided, and the sensor units are positioned in a vertical position and a horizontal position with respect to a tire ground contact surface. Sensor-equipped wheel bearings arranged on the upper surface, the lower surface portion, the right surface portion, and the left surface portion so as to have a phase difference of 90 degrees in the circumferential direction.   5. The wheel bearing with sensor according to claim 1, wherein the heat insulating material is made of resin or rubber.   6. The wheel bearing with sensor according to claim 5, wherein the heat insulating material is made of a foam material.   The sensor-equipped wheel bearing according to any one of claims 1 to 6, wherein the heat insulating material is a covering layer that covers an exposed surface of the sensor unit exposed to the outside air.   7. The sensor unit, a signal processing IC that processes an output signal of the sensor, and a wiring system of these sensors and the signal processing IC are arranged around the periphery of the fixed side member according to claim 1. The sensor is disposed inside an annular protective cover attached to the surface, and the protective cover has an opening that exposes the sensor unit at the arrangement portion of the sensor unit, and the opening is sealed with the heat insulating material. Wheel bearing.   7. The sensor-equipped wheel bearing according to claim 1, wherein the sensor unit is covered with a protective cover, and a heat insulating material is filled in the protective cover.   7. The sensor according to claim 1, wherein the sensor unit is covered with a protective cover, and an air layer is sealed inside the protective cover as the heat insulating material that shields the sensor unit from outside air. Wheel bearing.   11. The sensor-equipped wheel bearing according to claim 9 or 10, wherein the protective cover has an annular shape and is attached to a peripheral surface of the fixed side member concentrically with the fixed side member.   12. The sensor-equipped wheel bearing according to claim 8, wherein the protective cover is made of stainless steel.   The surface of the sensor unit and the periphery of the sensor unit installation portion on the peripheral surface of the fixed-side member according to any one of claims 1 to 12, as compared with an average thermal conductivity of a resin material. Wheel bearing with sensor covered with a material with high thermal conductivity.

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