JP2010138959A - Sensor-equipped bearing for wheel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sensor-equipped bearing for a wheel which can stably detect with high accuracy a load acting on the bearing for the wheel or a tire contact area by correcting a detection error due to a temperature difference between bearing interior and exterior sections. <P>SOLUTION: Rolling bodies 5 are interposed between opposed double-row rolling surfaces 3, 4 of an outer member 1 and an inner member 2. The outer member 1 or the inner member 2, which is a fixed side member, is provided with one or more sensor units 20. The sensor unit 20 comprises a distortion generating member 21 making contact with and fixed to the fixed side member, a sensor 22 detecting the distortion, and a sensor section temperature sensor 28 detecting a temperature of an installation section of the sensor. A rolling surface temperature sensor 29 detecting a temperature of a location adjacent to the rolling surface 3 is provided in the fixed side member, and an estimating means 30 is provided to estimate the load acting on the bearing for the wheel or the tire from a correction signal obtained by correcting a sensor output signal of the sensor unit 20 with outputs of the sensor section temperature sensor 28 and the rolling surface temperature sensor 29. <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 changes, the output signal of the strain sensor fluctuates due to the temperature characteristics of the strain sensor and the difference in linear expansion coefficient between the fixed ring and the sensor unit. To do. For this reason, when the load applied to the wheel bearing is calculated and estimated from the output signal of the strain sensor, the error of the load becomes large.

  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 in the vicinity of the strain sensor, and the above-described line is obtained by the output of the temperature sensor. It is conceivable to correct the strain sensor output signal due to the difference in expansion coefficient and the temperature characteristics of the strain sensor itself.

  However, for example, the internal temperature and surface temperature of the outer ring, which is a fixed ring of the wheel bearing, are the heat generated inside the bearing (near the rolling surface) due to the load and changes in contact conditions with the outside air (wind, moisture, temperature). It is often different for each. In this state, the thermal strain due to the temperature gradient from the outer ring to the surface is superimposed on the strain sensor output signal. This thermal distortion cannot be reduced by the correction by the output of the temperature sensor described above, and the detection error becomes large. Therefore, in order to detect the load with high accuracy, a new measure for correcting the influence of the thermal distortion described above is required.

  An object of the present invention is to provide a sensor-equipped wheel bearing capable of correcting a detection error due to a temperature difference between the inside and outside of the bearing and stably detecting a load acting on the wheel bearing and the tire ground contact surface with high 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 strain generating member having two or more contact fixing portions fixed in contact with the sensor, a sensor attached to the strain generating member to detect strain of the strain generating member, and the sensor attached to the strain generating member One or more sensor units comprising a sensor part temperature sensor for detecting the temperature of the installation part are provided, and rolling is performed to detect the temperature in the vicinity of the rolling surface at a circumferential position in the vicinity of the sensor unit in the stationary member. A surface temperature sensor, A sensor unit sensor output signal is corrected by the sensor unit temperature sensor and the rolling surface temperature sensor output, and an estimation means for estimating a load applied to the wheel bearing or the tire from the corrected signal is provided. To do. The stationary member may be an outward member, for example. The circumferential position in the vicinity of the sensor unit on which the rolling surface temperature sensor is provided may be the same circumferential position as the sensor unit, or may be in the vicinity thereof.
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 sensor, and the output Hysteresis generated in the signal is also reduced, and the load can be estimated with high accuracy.
In particular, in the estimation means for estimating the load, the sensor unit temperature sensor that is attached to the strain generating member of the sensor unit and detects the temperature of the sensor installation unit, and the circumferential member in the vicinity of the sensor unit in the fixed side member are provided. Because the output signal of the sensor of the sensor unit is corrected by the output of the rolling surface temperature sensor that detects the temperature near the rolling surface, the load applied to the wheel bearing or tire is estimated from the corrected signal. By correcting the detection error due to the temperature difference between the inside and outside of the bearing, it becomes possible to reduce the influence of changes in the outside air temperature and fluctuations in the internal heat generation of the bearing due to load changes, acting on the wheel bearings and the tire ground contact surface The load can be detected with high accuracy and stability.

  In this invention, it is good also as what provides three or more said sensor units, and the said estimation means estimates the radial direction load and axial load which are added to the wheel bearing or a tire from the output signal of the sensor 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 a tire ground contact surface. You may arrange | position so that a 90 degree phase difference may be made | formed in the circumferential direction on the left surface part. In this configuration, the load can be accurately estimated under any load condition. That is, when the load in a certain direction increases, the portion where the rolling element and the rolling surface are in contact with each other and the portion not in contact appear with a 180-degree phase difference. 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 sensor.

  In this invention, the number of rolling surface temperature sensors may be the same as the number of sensor units, and each rolling surface temperature sensor may be provided in accordance with the circumferential position and phase of each sensor unit in the fixed side member. good. In the case of this configuration, the temperature in the vicinity of the rolling surface corresponding to each sensor unit can be detected, the temperature correction by the estimation means can be performed with higher accuracy, and the load detection accuracy can be improved accordingly. .

  In this invention, the estimation means corrects the output signal of the sensor of the sensor unit based on the difference between the output of the sensor unit temperature sensor and the output of the rolling surface temperature sensor, and the correction amount is prepared in advance. It is good also as what determines from the linear approximation relational expression of the output difference of both said temperature sensors, and a correction amount. In the case of this configuration, the amount of offset superimposed on the sensor output signal of the sensor unit, that is, the thermal distortion due to the temperature gradient from the inside to the surface of the stationary member can be sufficiently reduced, and the accuracy of the load estimated value can be improved. .

  In this invention, the fixed side member may be provided with a hole reaching the vicinity of the rolling surface, and the rolling surface temperature sensor may be embedded in the hole.

  In the present invention, a through-hole penetrating in the radial direction is provided at an intermediate position between the double-row rolling surfaces of the fixed side member, and the rolling surface temperature sensor connected to the signal line inserted through the through-hole is rolled. It may be provided near the running surface. In the case of this configuration, the rolling surface temperature sensor can be easily installed near the rolling surface of the fixed member.

  In this invention, a ring-shaped temperature sensor support member may be fitted to the peripheral surface on which the rolling surface of the fixed member is formed, and the rolling surface temperature sensor may be embedded in the temperature sensor support member. In the case of this configuration, the rolling surface temperature sensor can be fixed and aligned easily.

  In this invention, you may provide the flexible substrate for mounting and wiring of the said rolling surface temperature sensor inside the said temperature sensor support member. In the case of this configuration, since the wiring process of the rolling surface temperature sensor can be performed inside the temperature sensor support member using the flexible substrate, the wiring process is easy, the configuration becomes compact, and the occurrence of disconnection or the like can be eliminated. Even when a plurality of rolling contact surface temperature sensors are arranged, wiring and fixing work can be easily performed.

  In the present invention, a plurality of rolling surface temperature sensors may be provided, and signal lines connected to these temperature sensors may be inserted into one through hole to seal the through hole. In the case of this configuration, wiring processing is facilitated, and moisture can be prevented from entering the inside of the fixed side member through the through hole.

  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 strain generating member having two or more contact fixing portions fixed in contact with the sensor, a sensor attached to the strain generating member to detect strain of the strain generating member, and the sensor attached to the strain generating member One or more sensor units comprising a sensor part temperature sensor for detecting the temperature of the installation part are provided, and rolling is performed to detect the temperature in the vicinity of the rolling surface at a circumferential position in the vicinity of the sensor unit in the stationary member. A surface temperature sensor, The sensor unit sensor output signal is corrected by the sensor unit temperature sensor and the rolling surface temperature sensor output, and the estimation means for estimating the load applied to the wheel bearing or tire from the corrected signal is provided. By correcting the detection error due to the temperature difference, it is possible to stably detect the load acting on the wheel bearing and the tire ground contact surface with high accuracy and stability.

  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 knuckle attachment 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, thereby A 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.

  Four sensor units 20 are provided on the outer diameter surface of the outer member 1 which is a fixed member. Here, these 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 and rear position with respect to the tire ground contact surface. Are provided so as to form a phase difference of 90 degrees.

  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 sensor 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 such as a steel material and is made of a thin plate material having a thickness of 2 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 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. Note that, depending on the shape of the strain generating member 21, two or more contact fixing portions 21a may be provided. 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, the 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 detects the strain in the circumferential direction around the notch portion 21b. To do. 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. Even if an excessive load is applied to the bearing, the assumed maximum force is the maximum force within a range in which the normal function as the bearing excluding the sensor system is restored when the load is removed.

  In the sensor unit 20, the two contact fixing portions 21a of the strain generating member 21 are located at the same dimension in the axial direction of the outer member 1, and the two contact fixing portions 21a are separated from each other in the circumferential direction. These contact fixing portions 21a are fixed to the outer diameter surface of the outer member 1 by bolts 24 via spacers 23, respectively. Each 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.

  A protective cover 35 that covers each sensor unit 20 is provided on the outer periphery of the outer member 1 that is a stationary member. As shown in FIG. 1, the protective cover 35 has an L-shaped cross section having a cylindrical portion 35a extending in the axial direction and a standing plate portion 35b extending from the end of the cylindrical portion 35a toward the inner diameter side. 1 and a concentric ring-shaped member. The inner diameter side end of the standing piece portion 35b of the protective cover 35 is the outer diameter surface of the outer member 1, and the inboard side end of the cylindrical portion 35a of the protective cover 35 is the outboard of the vehicle body mounting flange 1a of the outer member 1. The protective cover 35 is attached to the outer member 1 so as to cover all the sensor units 20 provided on the outer diameter surface of the outer member 1 by being fixed to the side surfaces facing each other. A gap is provided between the inboard side end of the cylindrical portion 35 a of the protective cover 35 and the outer diameter surface of the outer member 1. The material of the protective cover 35 may be plastic or rubber, or may be made of metal.

  Further, as shown in FIG. 1, the signal line 36 of the strain sensor 22, the signal line 37 of the sensor temperature sensor 28, and the signal line of the rolling contact surface temperature sensor 29 described later in all the sensor units 20 covered with the protective cover 35. 38 is pulled out from one place of the protective cover 35 to the outside of the protective cover. For example, in the example of FIG. 1, the signal lines 36 of all strain sensors 22, the signal lines 37 of all sensor temperature sensors 28, and the signal lines 38 of all rolling surface temperature sensors 29 are connected to the cylindrical portion of the protective cover 35. 35a extending from one place in the circumferential direction on the inner circumferential surface of 35a to the inboard side, a trough in the vehicle body mounting flange 1a of the outer member 1, that is, between the two projecting pieces 1aa (FIG. 2) adjacent in the circumferential direction. I try to pull it out from the position.

  Further, as shown in an enlarged cross-sectional view in FIG. 5, the outer member 1 that is a fixed side member detects the temperature in the vicinity of the rolling surface 3 in the outboard side row among the rolling rows 3 in the double row. A rolling surface temperature sensor 29 is provided. Four rolling surface temperature sensors 29 are provided corresponding to the four sensor units 20 provided on the outer diameter surface of the outer member 1. Each rolling contact surface temperature sensor 29 is arranged at a circumferential position in the vicinity of the sensor unit 20 in the outer member 1 that is a fixed member. Specifically, each rolling contact surface temperature sensor 29 extends to the outer member 1 in the radial direction from the vicinity of the installation portion of each sensor unit 20 on the outer diameter surface and reaches the vicinity of the rolling contact surface 3. Four temperature sensor embedding holes 32 are provided, and the rolling surface temperature sensors 29 are embedded in the bottom portions of the holes 32 near the rolling surface 3. The bottom of each hole 32 is preferably as close to the rolling surface 3 as long as the bearing life is not reduced by the formation of these holes 32. For example, the quench hardening layer and the uncured portion of the rolling surface 3 Near the boundary. The signal line 38 connected to each of the rolling surface temperature sensors 29 passes through the corresponding sensor unit 20 from the temperature sensor embedding hole 32 and together with the other signal lines 36 and 37, as described above, the protective cover. It is pulled out from 35.

  The strain sensor 22, the sensor part temperature sensor 28, and the rolling surface temperature sensor 29 of the sensor unit 20 are connected to the estimation unit 30. The estimation means 30 estimates the force (vertical load Fz, load Fx serving as driving force, axial load Fy) acting between the wheel bearing and the wheel and the road surface (tire contact surface) based on the output signal of the strain sensor 22. Temperature correction means 31 for correcting the output signal of the strain sensor 22 with the outputs of the sensor part temperature sensor 28 and the rolling surface temperature sensor 29. The estimation unit 30 estimates the vertical load Fz, the load Fx as a driving force, and the axial load Fy from the output signal of the strain sensor 22 corrected by the temperature correction unit 31.

  Since the output signal of the strain sensor 22 has a temperature drift characteristic, if the output signal of the strain sensor 2 is corrected by the temperature of the sensor unit 20 measured by the sensor temperature sensor 28 provided in the sensor unit 20 or the outside air temperature. Detection errors due to temperature drift characteristics can be reduced. However, if the amount of heat generated inside the bearing or the state of heat radiation to the outside air of the bearing changes, the thermal strain component of the outer member 1 is superimposed on the output signal of the strain sensor 22 to deteriorate the detection accuracy.

Therefore, the temperature correction means 31 in the estimation means 30 includes the temperature Ts of the installation part of the strain sensor 22 detected by the sensor part temperature sensor 28 and the internal temperature of the outer member 1 detected by the rolling contact surface temperature sensor 29. Based on the temperature Ti in the vicinity of the rolling surface 3, the output signal of the strain sensor 22 is corrected as follows.
First, ΔT = Ti−Ts is obtained as the temperature difference between the inside and outside of the outer member 1. The relationship between the temperature gradient inside and outside the outer member 1 and the offset amount superimposed on the output signal of the strain sensor 22 is determined by the structure of the outer member 1 and can be approximated by a proportional relationship as shown in the graph of FIG. In FIG. 6, the temperature of the sensor unit 20 is constant, and the output signal of the strain sensor 22 when the temperature difference ΔT = 0 is S0.
Next, the temperature correction unit 31 obtains a coefficient from the graph of FIG. 6, and uses the internal / external temperature difference ΔT to calculate the correction value of the output signal of the strain sensor 22.
Correction value = (output of strain sensor 22) + (offset O (Ts) due to sensor temperature)
+ (Offset G (ΔT) due to temperature gradient)
Asking. However,
O (Ts): offset amount due to difference in linear expansion + temperature characteristic of strain sensor 22 G (ΔT): offset amount due to temperature gradient

  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 to the outer member 1, the strain of the outer member 1 is transmitted to the strain generating member 21 in an enlarged manner, and the strain is distorted. The sensor 22 is detected with high sensitivity, the hysteresis generated in the output signal is also reduced, and the load can be estimated with high accuracy.
In particular, a sensor part temperature sensor 28 for detecting the temperature of the installation part of the strain sensor 22 is attached to the strain generating member 21 of the sensor unit 20, and the rolling surface 3 is positioned at a circumferential position in the vicinity of the sensor unit 20 in the outer member 1. A rolling surface temperature sensor 29 for detecting the temperature in the vicinity of the sensor is provided. In the estimation unit 30, the temperature correction unit 31 corrects the output signal of the strain sensor 22 with the outputs of the sensor temperature sensor 28 and the rolling surface temperature sensor 29. Since the load applied to the wheel bearing or tire is estimated from the corrected signal, it becomes possible to reduce the influence of changes in the outside air temperature and fluctuations in the internal heat generation of the bearing due to the load change. Loads acting on bearings and tire contact surfaces can be detected with high accuracy and stability, making it less susceptible to load detection even when there is rainfall or changes in the outside air temperature.

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 detection load obtained from this sensor-equipped wheel bearing for vehicle control, the detection accuracy will not deteriorate even when traveling under conditions with high load, and safety will be improved by accurate vehicle control. Can do.

  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.

  In this embodiment, the number of the rolling surface temperature sensors 29 is four, which is the same as the number of the sensor units 20, and the circumferential position and phase of each sensor unit 20 in the outer member 1 are matched to each other. Since the rolling surface temperature sensor 29 is provided, the temperature in the vicinity of the rolling surface corresponding to each sensor unit 20 can be detected, and correction by the temperature correction unit 31 of the estimation unit 30 can be performed with higher accuracy. And the accuracy of the finally obtained load estimated value can be improved accordingly.

  In this embodiment, the temperature correction means 31 of the estimation means 30 causes the output signal of the strain sensor 22 of the sensor unit 20 based on the difference between the output of the sensor unit temperature sensor 28 and the output of the rolling surface temperature sensor 29. The correction amount is determined from the first-order approximate relational expression (FIG. 6) between the output difference between the temperature sensors 28 and 29 and the correction amount prepared in advance. The amount of offset superimposed on the outer member 1, that is, the thermal distortion due to the temperature gradient from the inside to the surface of the outer member 1, can be sufficiently reduced, and the accuracy of the estimated load value can be improved.

  7 and 8 show another installation example of the rolling contact surface temperature sensor 29 in the embodiment. In this installation example, one through hole 33 penetrating in the radial direction is provided at an intermediate position of the double row rolling surface 3 of the outer member 1 which is a fixed member, and the rolling surface temperature sensor is provided in the through hole 33. The rolling contact surface temperature sensor 29 is disposed in the vicinity of the rolling contact surface 3 of the outer member 1 by inserting the signal line 38 connected to the reference numeral 29. The signal line 38 of the rolling contact surface temperature sensor 29 passes through the sensor unit 20 and is drawn out from one place of the protective cover 35 together with the signal line 36 of the strain sensor 22 and the signal line 37 of the sensor unit temperature sensor 28.

A ring-shaped temperature sensor support member 39 shown in FIG. 8A is press-fitted and fitted in the vicinity of the rolling surface 3 whose temperature is detected by the rolling surface temperature sensor 29 on the inner diameter surface of the outer member 1. A rolling surface temperature sensor 29 is embedded in the temperature sensor support member 39. As shown in the partial cross-sectional view of FIG. 8B, the temperature sensor support member 39 is provided with a recessed portion 39a in a part of its inner diameter surface, and the wiring of the rolling contact surface temperature sensor 29 is formed in the recessed portion 39a. The flexible substrate 40 is provided, and the rolling surface temperature sensor 29 is mounted on the flexible substrate 40. FIG. 8A shows an example in which the rolling surface temperature sensor 29 is provided in one recessed portion 39a of the temperature sensor support member 39, but each circumferential direction corresponding to the installation portion of each sensor unit 20 is shown. You may provide the four rolling surface temperature sensors 29 divided into a position. By measuring the rolling surface temperature at each position, temperature correction can be performed with higher accuracy.
The signal line 38 of each rolling contact surface temperature sensor 29 passes through one through hole 33 and is drawn to the outer peripheral side of the outer member 1, and the through hole 33 is sealed by a seal member 41.

  In this installation example of the rolling contact surface temperature sensor 29, a through hole 33 that penetrates in the radial direction is provided at an intermediate position of the double row rolling contact surface 3 of the outer member 1, and the signal line 38 inserted through the through hole 33. Since the rolling surface temperature sensor 29 connected to is provided in the vicinity of the rolling surface 3, the rolling surface temperature sensor 29 can be easily installed in the vicinity of the rolling surface 3 on the inner diameter surface of the outer member 1.

  Further, a ring-shaped temperature sensor support member 39 is fitted to the inner diameter surface of the outer member 1 where the rolling surface 3 is formed, and the rolling surface temperature sensor 29 is embedded in the temperature sensor support member 39. The rolling surface temperature sensor 29 can be fixed and aligned easily.

  Moreover, since the flexible substrate 40 for mounting and wiring of the rolling surface temperature sensor 29 is provided inside the temperature sensor support member 39, the flexible substrate 40 is used to roll inside the temperature sensor support member 39. Wiring processing of the surface temperature sensor 29 can be performed, wiring processing is easy, the configuration is compact, and occurrence of disconnection or the like can be eliminated. Even when a plurality of rolling contact surface temperature sensors 29 are arranged, wiring and fixing work can be easily performed.

  Further, a plurality of rolling contact surface temperature sensors 29 are provided, and signal lines 38 connected to these temperature sensors 29 are inserted into one through hole 33, and this through hole 33 is sealed with a seal member 41. Wiring processing is facilitated, and moisture can be prevented from entering the outer member 1 through the through hole 33.

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 an expanded sectional view of the installation part of the rolling surface temperature sensor in the wheel bearing with the same sensor. It is a graph which shows the relationship between the internal / external temperature difference of an outer member, and a distortion sensor output. It is an expanded sectional view which shows the other example of installation of the rolling surface temperature sensor in the wheel bearing with a sensor. (A) is a perspective view of the temperature sensor support member used for the installation example of the rolling surface temperature sensor, (B) is the fragmentary sectional view.

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 ... Sensor part temperature sensor 29 ... Rolling surface Temperature sensor 30 ... Estimating means 31 ... Temperature correcting means 32 ... Temperature sensor embedding hole 33 ... Through hole 39 ... Temperature sensor support member 40 ... Flexible substrate 41 ... Sealing member

Claims (11)

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 parts fixed in contact with the fixed side member of the outer member and the inner member, and detecting the strain of the strain generating member attached to the strain generating member And at least one sensor unit comprising a sensor part temperature sensor that is attached to the strain generating member and detects the temperature of the sensor installation part, and in the circumferential direction of the fixed member in the vicinity of the sensor unit A rolling surface temperature sensor for detecting the temperature in the vicinity of the rolling surface is provided at the position, and the output signal of the sensor of the sensor unit is corrected with the output of the sensor unit temperature sensor and the rolling surface temperature sensor, and the corrected signal A wheel bearing with a sensor, characterized in that an estimation means for estimating a load applied to a wheel bearing or a tire 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 output signals of sensors of these sensor units. A wheel bearing with sensor.   4. The sensor unit according to claim 1, wherein four sensor units are provided, and the sensor units are arranged on an outer diameter surface of the fixed side member that is in a vertical position and a horizontal position with respect to a tire ground contact surface. A sensor-equipped wheel bearing disposed on the upper surface, the lower surface, the right surface, and the left surface so as to have a phase difference of 90 degrees in the circumferential direction.   5. The method according to claim 1, wherein the number of the rolling surface temperature sensors is the same as the number of sensor units, and the circumferential position and phase of each sensor unit in the stationary member are matched. Sensor wheel bearing with each rolling contact surface temperature sensor.   6. The sensor according to claim 1, wherein the estimating unit corrects an output signal of the sensor of the sensor unit based on a difference between an output of the sensor unit temperature sensor and an output of the rolling contact surface temperature sensor. It is assumed that the correction amount is determined from a first-order approximate relational expression between the output difference between the two temperature sensors and the correction amount prepared in advance.   7. The sensor-equipped wheel bearing according to claim 1, wherein a hole reaching the vicinity of a rolling contact surface is provided in the fixed side member, and the rolling contact surface temperature sensor is embedded in the hole.   The through-hole penetrating in the radial direction is provided at an intermediate position of the double-row rolling surface of the fixed side member according to any one of claims 1 to 7, and connected to a signal line inserted through the through-hole. The wheel bearing with a sensor which provided the said rolling contact surface temperature sensor near the rolling contact surface.   9. The sensor-equipped wheel according to claim 8, wherein a ring-shaped temperature sensor support member is fitted to a peripheral surface on which the rolling surface of the fixed side member is formed, and the rolling surface temperature sensor is embedded in the temperature sensor support member. Bearings.   The sensor-equipped wheel bearing according to claim 9, wherein a flexible substrate for mounting and wiring of the rolling surface temperature sensor is provided inside the temperature sensor support member.   11. The rolling surface temperature sensor according to claim 8, wherein a plurality of the rolling surface temperature sensors are provided, signal lines connected to the temperature sensors are inserted into one through hole, and the through hole is sealed. Bearing for sensor wheel.

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