JP2006234080A - Rolling bearing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately measure a load acting on a wheel in a rolling bearing unit for the wheel. <P>SOLUTION: In this rolling bearing unit 10 for supporting the wheel, a hub unit 13 fixing the wheel is supported on the inner diameter side of an outer ring 18 supported on a suspension device. The hub unit 13 comprises a hub body 12 and an inner ring 19 fitted to the inner end part of the hub body 12. Outer and inner row balls 20a and 20b are rollingly installed between the inner ring 19 and the outer ring 18 in the state of being held by inner and outer row cages 22a and 22b to form a two-row angular ball bearing. An inner row optical sensor 24b detects the surface moving speed of the inner row balls 20b and an outer row optical sensor 24a detects the surface moving speed of the outer row balls 20a. The load acting on the wheel can be calculated by a variation in the surface moving speed of the outer and inner row balls 20a and 20b detected by the optical sensors 24a and 24b. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a rolling bearing device, and more particularly to a rolling bearing device for supporting a wheel.

  Anti-lock brake system (ABS) that prevents tire locking during sudden braking as a vehicle control means, and traction control system (TCS) that controls idling of drive wheels that are likely to occur when starting on a slippery road or accelerating Drive control corresponding to various driving conditions and road surface conditions is performed. In order to ensure the running stability of the vehicle, it is necessary to accurately measure the wheel speed and the load applied to the wheel and effectively use it for these controls to improve the response and accuracy of the control.

Strain sensors and displacement sensors are attached to the wheel bearing rolling bearing unit that rotatably supports the vehicle wheel with respect to the suspension system, and the load applied to the rolling bearing unit during vehicle traveling is detected to control the vehicle. It is being used. For example, Patent Literature 1 discloses a hub unit with a strain sensor that measures a ground load by a strain sensor.
JP 2003-336653 A

  In the hub unit with a strain sensor as in Patent Document 1, the strain sensor is provided on the vehicle body side track member, and a bearing is interposed between the tire and the vehicle body side track member until force is transmitted to the vehicle body side track member. The measurement result error is large. In addition, the measurement results vary depending on the bonding method, the mounting angle, the mounting location, and the like of the strain sensor. Moreover, since the force transmitted via the bearing is measured, the load cannot be accurately measured due to the phase delay.

  In addition, the vertical load fluctuation and left-right load fluctuation of the wheel act on the bearing unit as the same moment force, but when the bearing unit is away from the center of the wheel, the vertical load and left-right load should be measured separately with a strain sensor. It is difficult. Generally, in a wheel bearing unit, it is not easy to distinguish and measure loads acting in the vertical direction, left-right direction, and front-rear direction of the vehicle, including the moment load applied to the wheel.

  This invention is made | formed in view of such a condition, The objective is to provide the rolling bearing apparatus which can measure the load added to a wheel accurately.

  In order to solve the above-described problems, a rolling bearing device according to an aspect of the present invention includes a wheel support hub unit including a rolling member including a plurality of rolling elements and a holding body that holds the plurality of rolling elements, A load measuring device for measuring a load acting on the wheel. The load measuring device estimates a load acting on a wheel from a detected amount related to a change in the rotational trajectory of the rolling element, and a detected amount related to a change in the rotational trajectory of the rolling element. A load amount estimating unit.

  The “amount related to the change in the rolling trajectory of the rolling element” is an amount resulting from a change in the rolling trajectory of the rolling element. For example, the change in the moving speed of the surface of the rolling element due to the deviation of the rotation center, the axle of the rolling element For example, changes in the revolution speed of surroundings. As an example, the rolling element trajectory change detection unit may be a non-contact sensor such as an optical sensor.

  According to this aspect, the amount of load acting on the wheel can be measured with high accuracy. Further, the load can be measured without phase delay with respect to the load input to the wheel.

  The rolling element trajectory change detection unit detects the moving speed of the surface of the rolling element as an amount related to the change of the rotating trajectory of the rolling element, and the load measuring device is configured to maintain the moving speed of the surface of the rolling element. You may further provide the speed deviation detection part which detects the deviation which deviates from the revolution speed of a body. The load amount estimation unit may estimate the load amount from the detected deviation. Due to the load acting on the wheel, the contact trajectory of the rolling element changes and the center of rotation of the rolling element shifts, so that a change appears in the moving speed of the surface of the rolling element when the load is applied. By detecting a change in the moving speed of the surface of the rolling element, it is possible to determine the amount of load acting.

  The rolling members are provided in double rows in the axle direction, the rolling element track change detection unit detects an amount related to a change in the rotating track of the rolling elements of the rolling members in each row, and the load measuring device is A load direction determination unit that determines the direction of the load acting on the wheel from a combination of the amounts related to the change in the rotation trajectory detected for the rolling elements in each row may be further provided. The rolling element trajectory change detection unit detects an amount related to a change in the rotational trajectory of the rolling element in a vertical or horizontal position when viewed from the axle direction, and the load measuring device is in the vertical or horizontal position. You may further provide the load direction determination part which determines the direction of the load which acts on a wheel from the combination of the quantity regarding the change of the said rotation track detected about a certain said rolling element. Furthermore, when the rolling members are provided in a double row in the axle direction, the rolling element track change detection unit relates to a change in the rotational track of the rolling elements in the vertical or horizontal position when viewed from the axle direction for each row. The load direction determination unit determines the direction of the load acting on the wheel from the combination of the amounts related to the change of the rotation trajectory detected for the rolling elements in the vertical and horizontal positions of each row. May be. Thereby, the load can be measured by distinguishing the direction of the load acting on the wheel.

  The load measuring device may further include a rotation center deviation direction detection unit that detects a direction in which the rotation centers of the plurality of rolling elements are shifted based on a detection result by the rolling element trajectory change detection unit. The load direction determination unit may determine the direction of the load from a combination of shift directions of the rotation centers detected for the plurality of rolling elements. The rotation center shift direction detection unit may detect a shift direction of the rotation center of the rolling element at a vertical or horizontal position when viewed from the axle direction. Furthermore, when the rolling members are provided in double rows in the axle direction, the rotation center deviation direction detection unit may detect a deviation direction of the rotation centers of the rolling elements in each row. Depending on the direction of the load acting on the wheel, a difference in the direction of deviation of the center of rotation of the rolling elements arranged in the vertical and horizontal directions of each row appears. By detecting the shift direction of the rotation center of the rolling elements arranged in the vertical and horizontal directions of each row, it is possible to determine the moment force, vertical force, lateral force, and longitudinal force acting on the wheel at the rotation center.

  The rolling members are provided in double rows in the axle direction, and the rolling element track change detection unit is configured to determine the amount of the rolling elements in each row as an amount related to a change in the rotational trajectory of the rolling members of the rolling members in each row. The revolution speed may be detected, and the load amount estimation unit may estimate the load amount from a difference in revolution speed of the detected rolling elements in each row. A change appears in the revolution diameter of the rolling elements in each row due to the load acting on the wheels. By detecting the change in the revolution diameter of the rolling elements in each row, the acting load amount can be obtained.

  According to the rolling bearing device of the present invention, the load acting on the wheel can be accurately measured.

Embodiment 1
FIG. 1 is a diagram illustrating a configuration of a wheel bearing rolling bearing unit 10 according to the first embodiment. The wheel support rolling bearing unit 10 is a rolling bearing using a rolling element, and supports a hub unit 13 that fixes a wheel on the inner diameter side of an outer ring 18 supported by a suspension device.

  The hub unit 13 includes a hub main body 12 provided with a flange 14 for fixing a wheel at an outer end portion, and an inner ring 19 provided at an inner end portion of the hub main body 12. A wheel is coupled and fixed to the outer surface of the flange 14 by a stud 16.

  The wheel-supporting rolling bearing unit 10 uses two rows of angular ball bearings in the bearing portion. Between the inner ring 19 and the outer ring 18, the outer row bearing balls 20a and the inner row bearing balls 20b are arranged in the outer row. It is provided so that it can roll while being held by the cage 22a and the cage 22b in the inner row. The outer row and inner row bearing balls 20a and 20b are in contact with the inner ring raceway and the outer ring raceway at a certain angle with respect to the radial direction. This figure shows a cross-sectional view above the bearing shaft 11, but a plurality of outer and inner rows of bearing balls 20 a and 20 b are arranged around the bearing shaft 11 in a ring shape.

  Hereinafter, when it is not necessary to distinguish between the outer row and the inner row, the outer and inner row bearing balls 20a and 20b are collectively referred to simply as bearing balls 20, and the outer row and inner row retainers 22a and 22b. Are collectively referred to as a cage 22. A bearing ball is simply called a ball.

  The wheel-supporting rolling bearing unit 10 has a function of measuring a load applied to a wheel by using optical sensors 24a and 24b as an example of a non-contact sensor. The optical sensors 24a and 24b include a light emitter and a light receiver, and identify the irregularities on the surfaces of the balls 20 and the cage 22 based on the same principle as the optical sensors of an optical mouse widely used as computer input means. Then, the moving direction and moving speed of the ball 20 rotating at high speed are detected. As the optical sensors 24a and 24b, it is preferable to use a laser sensor or the like that has a sufficiently small surface irregularity detection area and has the ability to read movement of irregularities in a limited region with high accuracy.

  The optical sensor 24b for the inner row is installed in the cylindrical portion 17 attached to the outer ring 18, and detects the moving speed of the balls 20b and the cage 22b in the inner row. The optical sensor 24a for the outer row is installed near the outer end portion of the outer ring 18, and detects the moving speed of the balls 20a and the cage 22a of the outer row.

  The optical sensors 24a and 24b for the outer row and the inner row are respectively provided at four locations in the vertical and horizontal directions when viewed from the direction of the bearing shaft 11, and the balls 20a and 20b positioned in the vertical and longitudinal directions of the vehicle are rotated. Detect speed.

  FIG. 2 (a) is a diagram illustrating an installation location of the optical sensor 24a for observing the outer ball array. This figure is a schematic view of the bearing portion of the wheel bearing rolling bearing unit 10 as viewed from the direction of the bearing shaft 11. In this example, eight balls 20 a held by the outer row cage 22 a are annularly arranged around the bearing shaft 11.

  Four optical sensors 24Ua, 24Da, 24La, and 24Ra are installed on the outer ring 18. Two optical sensors 24La and 24Ra are provided on the left and right sides of the outer ring 18 corresponding to the longitudinal direction of the vehicle, and two optical sensors 24Ua and 24Da are provided on the upper and lower sides of the outer ring 18 corresponding to the vertical direction of the vehicle. The moving speed of the observation point indicated by each arrow is detected.

  FIG. 2B is a diagram for explaining an installation location of the optical sensor 24b for observing the inner ball array. Similar to the outer row, eight balls 20b held by the inner row cage 22b are arranged around the bearing shaft 11 in an annular shape. Four optical sensors 24Ub, 24Db, 24Lb, and 24Rb are installed in the cylindrical portion 17 attached to the outer ring 18. Two optical sensors 24Lb and 24Rb are provided on the left and right sides of the cylindrical portion 17 corresponding to the longitudinal direction of the vehicle, and two optical sensors 24Ub and 24Db are provided on the upper and lower sides of the cylindrical portion 17 corresponding to the vertical direction of the vehicle. Are provided to detect the moving speeds of the observation points indicated by arrows, respectively.

  Hereinafter, when there is no need to distinguish the upper, lower, left, and right installation positions of the optical sensors 24a and 24b in the outer row and the inner row, the symbols U, D, L, and R are omitted. The optical sensors 24a and 24b are collectively referred to simply as the optical sensor 24.

  As shown in FIGS. 2A and 2B, the optical sensor 24 has four locations in the vertical and horizontal directions when viewed from the direction of the bearing shaft 11 for both the outer and inner ball rows. A total of eight optical sensors 24 are provided. The sensor outputs of these eight optical sensors 24 are sent to an electronic control unit (ECU) 100 mounted on the vehicle body via a communication device.

  The ECU 100 detects a change in the moving speed of the surface of the ball 20 observed by the optical sensor 24. Since the change in the moving speed of the surface of the ball 20 observed by the optical sensor 24 is due to a change in the contact trajectory of the ball 20 due to the load acting on the wheel, the ECU 100 outputs the sensor output of the optical sensor 24. Thus, the load acting on the wheel can be obtained.

  FIG. 3 is a diagram illustrating a configuration of the ECU 100. The sensor output from the optical sensor 24 is input to the speed deviation detector 102. From the sensor output waveform of the optical sensor 24, the speed deviation detection unit 102 calculates the minimum value of the moving speed of the surface of the ball 20 detected by the optical sensor 24 (hereinafter referred to as peak speed) from the revolution speed of the cage 22. Deviation (hereinafter referred to as speed deviation) is detected, and the detected speed deviation is provided to the load amount estimation unit 104 and the rotation center deviation direction detection unit 108.

  The speed deviation is an amount that changes depending on the load applied to the wheel, and the speed deviation-load table 106 stores a correspondence relationship between the speed deviation and the load.

  The load amount estimation unit 104 refers to the speed deviation-load table 106 and estimates a load amount corresponding to the speed deviation detected by the speed deviation detection unit 102. For example, the load amount estimation unit 104 performs an interpolation calculation using a set of the speed deviation and the load amount stored in the speed deviation-load table 106, thereby calculating the speed deviation detected by the speed deviation detection unit 102. Calculate the corresponding load amount.

  The rotation center shift direction detection unit 108 is obtained from the sensor output waveforms of the optical sensors 24Ua, 24Da, 24La, 24Ra in the outer row and the optical sensors 24Ub, 24Db, 24Lb, 24Rb in the inner row that are arranged vertically and horizontally. The obtained speed deviation is received from the speed deviation detecting unit 102. Based on the speed deviation acquired from the speed deviation detection unit 102, the rotation center deviation direction detection unit 108 shifts the rotation centers of the outer row ball 20a and the inner row ball 20b from the position when there is no load. If it deviates, the direction is detected. The rotation center deviation direction detection unit 108 gives the load direction determination unit 110 the deviation direction of the rotation centers of the outer row balls 20 a and the inner row balls 20 b positioned vertically and horizontally.

  The direction of deviation of the rotation centers of the outer row balls 20a and the inner row balls 20b positioned in the vertical and horizontal directions depends on the direction of the load applied to the wheels. The load direction determination table 112 stores a correspondence relationship between a combination of a shift direction of the rotation center of the outer row ball 20a and the inner row ball 20b positioned in the upper, lower, left and right directions and the load direction.

  The load direction determination unit 110 refers to the load direction determination table 112 and detects the shift direction of the rotation center of the outer row ball 20a and the inner row ball 20b located in the upper, lower, left and right directions detected by the rotation center deviation direction detection unit 108. The load direction corresponding to the combination is determined.

  4A to 4D are views for explaining the principle of load measurement by the wheel-supporting rolling bearing unit 10. The wheel-supporting rolling bearing unit 10 is an angular ball bearing configured such that the ball 20 contacts the inner ring raceway and the outer ring raceway at a certain angle with respect to the radial direction, and receives an axial load, a radial load, and a moment load. Can do. When a load is applied, the contact point of the ball 20 changes and the contact trajectory changes.

  FIG. 4A shows the relationship between the contact trajectory of the ball 20 and the observation point 40 when there is no load. When no load is applied, the ball 20 is in contact with the inner ring raceway and the outer ring raceway at a certain angle with respect to the radial direction as shown in the figure. The contact state of the ball 20 is represented by a line 32 connecting the contact point of the inner ring raceway and the contact point of the outer ring raceway, and is inclined with respect to the radial direction. The ball 20 rotates in the direction of the arrow about the rotation center 30 while revolving around the bearing shaft 11 in contact with the inner ring raceway and the outer ring raceway. The optical sensor 24 is arranged so that the moving speed of the rotation center 30 of the ball 20 can be observed when there is no load. An observation point 40 of the optical sensor 24 is indicated by an arrow.

  FIG. 4B is a diagram showing a time change of the sensor output waveform of the optical sensor 24 when there is no load. The optical sensor 24 detects and outputs the moving speed of the ball 20 or the cage 22 at the observation point 40 in FIG. During the period of reference numeral 42, the optical sensor 24 detects the revolution speed of the cage 22. In the figure, the change in the sensor output of the optical sensor 24 is shown as a waveform with reference to the revolution speed of the cage 22. In the period indicated by reference numeral 44, the optical sensor 24 detects the moving speed of the surface of the ball 20 held by the holder 22. Since the ball 20 revolves together with the cage 22 and rotates by itself, the sensor output waveform of the optical sensor 24 has a downward convex waveform as shown in the figure. The moving speed (peak speed) of the surface of the ball 20 at the peak 46 of the downwardly convex output waveform is equal to the revolution speed of the cage 22.

  The reason why the sensor output waveform of the optical sensor 24 changes with time as shown in FIG. 2B when there is no load will be described with reference to FIG. FIG. 5A is a diagram illustrating the speed observed by the optical sensor 24 when there is no load. An observation locus 62 of the optical sensor 24 with respect to the ball 20 and the cage 22 is shown. While the optical sensor 24 is observing the cage 22, that is, during the period indicated by reference numeral 42 in FIG. 4B, the optical sensor 24 detects the revolution speed of the holder 22 indicated by reference numeral 50. ing.

  When the observation target of the optical sensor 24 is switched from the cage 22 to the ball 20, that is, when the period of the reference numeral 42 in FIG. The moving speed of the outermost edge of the ball 20 indicated by 56 is detected. The speed 56 is a speed obtained by synthesizing the rotation speed 54 of the ball 20 with the revolution speed 52 of the ball 20. Since the revolution speed 52 of the ball 20 is equal to the revolution speed 50 of the cage 22, the speed 56 of the outermost edge of the ball 20 obtained by synthesizing the revolution speed 54 of the ball 20 is higher than the revolution speed 50 of the cage 22. Also grows. For this reason, the sensor output of the optical sensor 24 becomes a value larger than the revolution speed at the beginning of the period of reference numeral 44 in FIG.

  As time further elapses, the observation point of the optical sensor 24 moves from the outermost edge of the ball 20 to the surface of the ball 20 and eventually reaches the rotation center 30. Since the influence of the rotation speed of the ball 20 gradually decreases as the observation point moves toward the rotation center 30 on the surface of the ball 20, the speed observed on the surface of the ball 20 gradually decreases.

  At the time when the optical sensor 24 observes directly above the rotation center 30, that is, at the time of the peak 46 in FIG. 4B, the optical sensor 24 detects the moving speed of the rotation center 30 indicated by reference numeral 58. Yes. At the rotation center 30, the ball 20 is only revolving, and the observation speed at this time is equal to the revolution speed of the ball 20, in other words, the revolution speed of the cage 22. For this reason, at the peak 46 in FIG. 4B, the sensor output of the optical sensor 24 is equal to the revolution speed.

  As the observation point passes through the center of rotation 30 and again moves toward the outermost edge of the ball 20, the effect of the rotation speed gradually increases, so that the observation speed of the surface of the ball 20 gradually increases. From the above, during the period of reference numeral 44 in FIG. 4B, the sensor output from the optical sensor 24 is such that the minimum value (peak speed) of the observation speed on the surface of the ball 20 matches the revolution speed of the cage 22. It is understood that the waveform is convex downward.

  Next, the time change of the sensor output of the optical sensor 24 when the load is applied will be described.

  FIG. 4C shows the relationship between the contact trajectory of the ball 20 and the observation point 40 when a load is applied. When the load is applied, the contact point of the ball 20 shifts, and the inner ring raceway and the outer ring raceway of the ball 20 change. A line 34 connecting the contact point of the inner ring track and the contact point of the outer ring track is more inclined with respect to the radial direction than the line 32 connecting the contact point of the original inner ring track and the contact point of the outer ring track. As a result, the observation point 40 of the optical sensor 24 is shifted from the rotation center 30 of the ball 20 when a load is applied.

  FIG. 4D is a diagram showing a time change of the sensor output waveform of the optical sensor 24 when a load is applied. The optical sensor 24 detects and outputs the moving speed of the ball 20 or the cage 22 at the observation point 40 in FIG. As in FIG. 4B, the optical sensor 24 detects the revolution speed of the cage 22 during the period 42, and the moving speed of the surface of the ball 20 held by the cage 22 during the period 44. Is detected. The sensor output waveform of the optical sensor 24 is a downward convex waveform in the period of 44, as in FIG. 4B. However, the movement of the surface of the ball 20 at the peak 48 of the downward convex output waveform is as follows. The speed (peak speed) is smaller than the revolution speed of the cage 22.

  With reference to FIG. 5B, the reason why the sensor output waveform of the optical sensor 24 changes with time as shown in FIG. FIG. 5B is a diagram for explaining the speed observed by the optical sensor 24 when a load is applied. While the optical sensor 24 is observing the cage 22, that is, during the period indicated by reference numeral 42 in FIG. 4D, the optical sensor 24 detects the revolution speed of the holder 22 indicated by reference numeral 50. ing. When the observation target of the optical sensor 24 is switched from the retainer 22 to the ball 20, that is, when the period of reference numeral 42 in FIG. The moving speed of the outermost edge of the ball 20 indicated by 56 is detected. This speed 56 is larger than the revolution speed 52 of the ball 20 due to the influence of the rotation speed 54 of the ball 20.

  As time further elapses, the observation point of the optical sensor 24 moves from the outermost edge of the ball 20 to the surface of the ball 20. As the observation point moves toward the center of the surface of the ball 20, the influence of the rotation speed of the ball 20 is gradually reduced, so that the speed observed on the surface of the ball 20 gradually decreases.

  However, since the rotation center 30 of the ball 20 is deviated from the observation locus 62 of the optical sensor 24 due to the load, even when the observation point of the optical sensor 24 reaches the center of the surface of the ball 20, the rotation speed of the ball 20. 59 occurs in the direction opposite to the revolution speed 52 of the ball 20. When the observation point reaches the center of the surface of the ball 20, the moving speed 60 of the surface of the ball 20 observed by the optical sensor 24 is a value obtained by subtracting the rotation speed 59 of the ball 20 from the revolution speed 52 of the ball 20. Become. Since the revolution speed 52 of the ball 20 is equal to the revolution speed 50 of the cage 22, the moving speed 60 of the surface of the ball 20 is slower than the revolution speed of the cage 22. This is the reason why the sensor output of the optical sensor 24 is smaller than the revolution speed of the cage 22 at the peak 48 in FIG.

  The minimum value (peak speed) of the moving speed of the surface of the ball 20 observed at the peak 48 of the sensor output of the optical sensor 24 when the load is applied as shown in FIG. The difference in the revolution speed of the vessel 22 increases as the acting load increases. Depending on the magnitude of the applied load, the amount of deviation of the trajectory of the ball 20 is determined, and the difference between the peak speed of the ball 20 and the revolution speed of the cage 22 is determined according to the amount of deviation of the trajectory of the ball 20. This relationship depends on the rigidity of the member.

  Therefore, by changing the magnitude of the load applied to the wheel by experiment or simulation, the deviation (speed deviation) in which the peak speed of the ball 20 deviates from the revolution speed of the cage 22 is measured, and the relationship between the load amount and the speed deviation is determined. Obtain in advance. The speed deviation-load table 106 stores the correspondence between the speed deviation and the load amount obtained in this way.

  The speed deviation detector 102 detects the peak 48 shown in FIG. 4D from the sensor output waveform of the optical sensor 24, detects the deviation in which the peak speed of the ball 20 deviates from the revolution speed of the cage 22, The load amount estimation unit 104 refers to the speed deviation-load table 106 to obtain a load amount corresponding to the detected speed deviation. Since the correspondence between the load and the speed difference may vary depending on the wheel speed, a plurality of speed deviation-load tables 106 storing the correspondence between the load and the speed deviation are stored for different wheel speeds. More preferably, the load amount estimation unit 104 obtains the load amount corresponding to the detected speed deviation by switching to and referencing the speed deviation-load table 106 corresponding to the wheel speed.

  When the rotation center 30 is shifted in the direction opposite to that in FIG. 5B with respect to the observation locus 62 of the optical sensor 24, the peak speed of the ball 20 is larger than the revolution speed of the cage 22. pay attention to. Therefore, the rotation center deviation direction detection unit 108 can identify whether the rotation center of the ball 20 has shifted to the outside from the observation locus 62 or to the inside of the observation locus 62 based on the sign of the speed deviation. The direction of deviation of the rotation center can be detected. The direction of deviation of the rotation center of the ball 20 depends on the direction of the acting load. In the present embodiment, not only the magnitude of the load but also the direction of the load can be obtained. Hereinafter, a method for obtaining the direction of load by the wheel bearing rolling bearing unit 10 of the present embodiment will be described.

FIG. 6 is a diagram for explaining the direction of the load acting on the wheel-supporting rolling bearing unit 10. The wheel bearing rolling bearing unit 10 is subjected to a bending moment M such as bending in the camber direction by lateral force input to the ground contact point of the wheel or torsion by self-aligning torque. Further, the wheel, and the lateral force F _H in the lateral direction, that the bearing axis of the vehicle, the vertical force F _v in the vertical direction, i.e. the vertical direction of the vehicle acts. Although not shown here, the longitudinal force in the longitudinal direction of the vehicle, that is, the direction perpendicular to the paper surface of the same figure also acts.

With reference to FIGS. 7 to 10, by using the sensor output results of a total of eight optical sensors 24 provided on the upper, lower, left, and right sides of the outer and inner ball rows shown in FIG. It will be described that the bending moment M, lateral force F _H , and vertical force F _v in FIG. 6 can be detected separately.

  FIG. 7 is a diagram for explaining a deviation between the rotation centers of the upper and lower balls in the outer row and the upper and lower balls in the inner row when the bending moment M is applied. In the figure, the solid line indicates the position of the ball when there is no load, and the wavy line indicates the position of the ball when the load is applied.

  When the bending moment M is applied to the upper and lower balls 20a and 21a, the upper ball 20a moves to the position indicated by reference numeral 20a 'with the contact trajectory shifted, and the rotation center 30a is accordingly moved to the reference numeral 30a. It shifts to the position indicated by 'and approaches the bearing shaft 11. On the other hand, the ball 21a on the lower side of the outer row shifts to the position indicated by reference numeral 21a 'with the contact trajectory shifted, and accordingly, the rotation center 31a shifts to the position indicated by reference numeral 31a' and moves away from the bearing shaft 11.

  For the upper and lower balls 20b and 21b in the inner row, due to the action of the bending moment M, the ball 20b on the upper side of the inner row moves to a position indicated by reference numeral 20b ′ with the contact trajectory shifted, and accordingly the rotation center 30b is moved to the reference numeral 30b. It shifts to the position indicated by 'and moves away from the bearing shaft 11. On the other hand, the ball 21b on the lower side of the inner row shifts to the position indicated by reference numeral 21b 'with the contact trajectory shifted, and accordingly, the rotation center 31b is shifted to the position indicated by reference numeral 31b' and approaches the bearing shaft 11.

FIG. 8 is a diagram for explaining a deviation between the rotation centers of the upper and lower balls in the outer row and the upper and lower balls in the case where the lateral force F _H is applied. As in FIG. 7, the solid line indicates the position of the ball when no load is applied, and the wavy line indicates the position of the ball when the load is applied.

When the lateral force F _H is applied to the upper and lower balls 20a and 21a, the ball 20a on the upper side of the outer row moves to the position indicated by reference numeral 20a ′ with the contact trajectory shifted, and the rotation center 30a is It shifts to the position indicated by 30a ′ and approaches the bearing shaft 11. Further, the ball 21a on the lower side of the outer row shifts to the position indicated by reference numeral 21a ′ with the contact trajectory shifted, and accordingly, the rotation center 31a is shifted to the position indicated by reference numeral 31a ′ and approaches the bearing shaft 11. As described above, the rotation center of the outer row balls approaches the bearing shaft 11 by the action of the inward lateral force F _H on the vehicle.

For the upper and lower balls 20b and 21b in the inner row, the ball 20b on the upper side of the inner row moves to the position indicated by reference numeral 20b ′ due to the action of the lateral force F _H , and accordingly the rotation center 30b is It shifts to the position indicated by 30b 'and moves away from the bearing shaft 11. Further, the ball 21b on the lower side of the inner row shifts to the position indicated by reference numeral 21b ′ with the contact trajectory shifted, and accordingly, the rotation center 31b is shifted to the position indicated by reference numeral 31b ′ and moves away from the bearing shaft 11. Thus, the rotation center of the balls in the inner row moves away from the bearing shaft 11 by the action of the inward lateral force F _H on the vehicle.

Figure 9 is a diagram for explaining the deviation of the rotation center of the outer column upper and lower balls and the inner column and below the ball when the vertical force F _V is applied. As in FIG. 7, the solid line indicates the position of the ball when no load is applied, and the wavy line indicates the position of the ball when the load is applied.

Outer row upper and lower balls 20a, for 21a, the vertical force F _H acts, outer row upper ball 20a is contacted trajectory deviation moves to the position indicated by the reference numeral 20a ', accordingly the rotation center 30a, the code It shifts to the position indicated by 30a ′ and moves away from the bearing shaft 11. On the other hand, the ball 21a on the lower side of the outer row shifts to the position indicated by reference numeral 21a ′ with the contact trajectory shifted, and the rotation center 31a shifts to the position indicated by reference numeral 31a ′ and approaches the bearing shaft 11.

With respect to the upper and lower balls 20b and 21b in the inner row, the ball 20b on the upper side of the inner row moves to the position indicated by reference numeral 20b ′ due to the action of the vertical force F _H , and accordingly the rotation center 30b is It shifts to the position indicated by 30b 'and moves away from the bearing shaft 11. On the other hand, the ball 21b on the lower side of the inner row moves to the position indicated by reference numeral 21b ′ with the contact trajectory shifted, and the rotation center 31b shifts to the position indicated by reference numeral 31b ′ and approaches the bearing shaft 11.

FIG. 10 summarizes the results of FIGS. 7 to 9, and when the bending moment M, lateral force F _H , and vertical force F _H are applied, the outer row upper side, the outer row lower side, and the inner row. It shows whether the direction in which the rotation centers of the balls on the upper side and the lower side of the inner row are shifted is a direction relatively approaching or moving away from the bearing shaft 11.

  When the bending moment M in FIG. 7 acts, the rotation center of the upper row of balls approaches the bearing shaft 11, and the rotation center of the lower row of balls moves away from the bearing shaft 11. On the other hand, the center of rotation of the ball on the upper side of the inner row moves away from the bearing shaft 11, and the center of rotation of the ball on the lower side of the inner row approaches the bearing shaft 11. That is, the direction in which the center of rotation is shifted between the outer row and the inner row is reversed.

When the lateral force F _{H in} FIG. 8 is applied, both the rotation center of the upper row ball and the rotation center of the lower row ball approach the bearing shaft 11. On the other hand, the center of rotation of the ball on the upper side of the inner row and the center of rotation of the ball on the lower side of the inner row both move away from the bearing shaft 11.

When the vertical force F _V of FIG 9 is applied, the rotation center of the outer column upper ball moves away from the bearing shaft 11, the rotation center of the ball of the outer row lower approaches the bearing shaft 11. Further, the center of rotation of the ball on the upper side of the inner row moves away from the bearing shaft 11, and the center of rotation of the ball on the lower side of the inner row approaches the bearing shaft 11. That is, the direction in which the center of rotation is shifted between the outer row and the inner row is the same.

According to the table of FIG. 10, the bending moment M, the lateral force F _H , and the vertical force F _H can be distinguished by a combination of the directions of deviation of the rotation centers of the upper and lower balls in the outer row and the inner row. The load direction determination table 112 stores the determination table of FIG. 10, and the load direction determination unit 110 detects the rotation centers of the upper and lower balls in the outer row and the inner row detected by the rotation center shift direction detection unit 108. Based on the combination of the deviation directions, the load direction determination table 112 is referenced to determine whether the applied load is a bending moment M, a lateral force F _H , or a vertical force F _H.

  In the above description, the outer row optical sensors 24Ua and 24Da and the inner row optical sensors 24Ub and 24Db arranged in the vehicle vertical direction are used to determine the rotation centers of the upper and lower balls in the outer row and the inner row. The direction of deviation was detected. Similarly, the left and right balls in the outer row and the inner row were detected using the optical sensors 24La and 24Ra in the outer row and the optical sensors 24Lb and 24Rb in the inner row arranged in the vehicle longitudinal direction. By detecting the direction of the shift of the center of rotation, it is possible to distinguish the longitudinal force acting on the wheel. The load direction determination table 112 also includes a determination table that stores the direction of deviation of the rotation centers of the left and right balls in the outer row and the inner row with respect to the longitudinal force. Similarly, regarding the bending moment, it is possible to distinguish not only the moment about the front and rear axes of the wheel shown in FIG. 7 but also the moment about the vertical axis.

  As described above, according to the wheel support rolling bearing unit 10 of the present embodiment, by detecting a change in the moving speed of the surface of the bearing ball using a non-contact sensor such as an optical sensor, The magnitude of the load applied to the wheel during traveling of the vehicle can be accurately measured. Further, the non-contact type sensor only needs to be retrofitted to the bearing, can be easily mounted, and can easily measure the load. In addition, since it is non-contact sensing using an optical sensor, the measurement result of the load is not affected by the specifications of the bearing, and a stable measurement result can be obtained.

  Further, in the wheel support rolling bearing unit 10 of the present embodiment, since the change in the moving speed of the bearing ball is detected by the non-contact type sensor, the phase delay from when the load is input to the wheel until the detected value is measured. Is very small, and the delay in load measurement is extremely small compared to the method of detecting the load by the strain of the member. Therefore, when the load measurement result is used for vehicle control, the control responsiveness can be improved.

  Furthermore, according to the wheel support rolling bearing unit 10 of the present embodiment, the optical sensors are arranged vertically and horizontally as viewed from the bearing shaft, and the direction of deviation of the rotation centers of the bearing balls in both the inner row and the outer row is determined. By detecting up, down, left and right, it is possible to distinguish all of vertical force, longitudinal force, left and right force, self-aligning torque, and camber torque, and it is possible to determine not only the magnitude of the load but also the direction of the load. .

  Based on the load amount and the load direction measured by the wheel support rolling bearing unit 10, the ECU 100 can detect a factor that impairs the running stability of the vehicle and perform appropriate drive control of the vehicle.

Embodiment 2
FIG. 11 is a diagram illustrating a configuration of the wheel supporting rolling bearing unit 10 according to the second embodiment. A description of the configuration common to the first embodiment will be omitted, and a configuration different from that of the first embodiment will be described.

  In the wheel-supporting rolling bearing unit 10 of the present embodiment, the revolution speed of the outer ball train and the inner ball train is measured by the optical sensor 24. The optical sensor 24 receives reflected light from the inner row of balls 20b or the inner row of holders 22b. The holder 22b that holds the inner row of balls 20b is provided with a slit, and the holder 22a that holds the outer row of balls 20a is provided with a reflector. The light emitted from the optical sensor 24 passes through the slit, is reflected by the reflecting plate, and reaches the optical sensor 24. Since the optical sensor 24 receives the reflected light and measures the revolution speed of the inner row and the outer row, the optical sensor 24 can measure even if the sensing capability is relatively low.

  FIGS. 12A to 12C are diagrams illustrating the configurations of the outer row cage 22a and the inner row cage 22b. As shown in FIG. 12A, the retainer 22b that holds the inner row of balls 20b is provided with a slit 23, and the reflector 22 is provided on the surface of the cage 22a that holds the outer row of balls 20a. ing. The light emitted from the optical sensor 24 passes through the slit 23 of the inner row retainer 22b and is reflected by the reflecting plate 25 of the outer row retainer 22a, and the reflected light is slit in the inner row retainer 22b. 23 is received by the optical sensor 24.

  FIG. 12B shows a position where the reflection plate 25 is provided in the cage 22a in the outer row as viewed from the direction of the bearing shaft 11. Here, as an example, eight balls 20a are annularly arranged in a state where they are held by outer rows of cages 22a, and a reflector 25 is attached to the surface of the cage 22a at a position between adjacent balls 20a. Has been.

  FIG. 12C shows a position where the slit 23 is provided in the cage 22 b in the inner row as viewed from the direction of the bearing shaft 11. Eight balls 20b are annularly arranged in a state of being held by the inner row of cages 22b, and slits 23 are provided at positions between adjacent balls 20b.

  When the outer row cage 22a and the inner row cage 22b are rotating while the vehicle is running, the position of the slit 23 of the inner row cage 22b on the rotation path and the reflector of the outer row cage 22a. When the position on the rotation path of the shaft 25 is exactly the same as viewed from the direction of the bearing shaft 11, the light that has passed through the slit 23 is reflected by the reflector 25 as shown in FIG. Received light. However, when the position of the slit 23 of the inner row cage 22b on the rotation path does not match the position of the reflection plate 25 of the outer row cage 22a on the rotation path, the light from the optical sensor 24 is not emitted. Even if it passes through the slit 23, it does not hit the reflecting plate 25, so that the reflected light is not received by the optical sensor 24.

  When no load is applied, the revolution speeds of the outer row cage 22a and the inner row cage 22b are equal, but when the load is applied, the positions where the outer row ball 20a and the inner row ball 20b come into contact with the raceway surface are shifted. Therefore, a difference occurs in the revolution speed of the outer row cage 22a and the inner row cage 22b. Therefore, when the load is applied, the difference in the frequency at which the light from the optical sensor 24 that has passed through the slit 23 hits the reflection plate 25 and is reflected due to the difference in revolution speed between the outer row cage 22a and the inner row cage 22b. Occurs.

  The ECU 100 obtains the difference between the revolution speed of the outer row retainer 22a and the revolution speed of the inner row retainer 22b from the frequency of the reflected light from the reflector 25 received by the optical sensor 24. The difference in revolution speed between the outer row cage 22a and the inner row cage 22b is due to the change in the contact trajectory between the outer ball train and the inner ball train due to the load acting on the wheels. The magnitude of the load can be obtained from the difference in revolution speed.

  FIG. 13 is a diagram illustrating a configuration of the ECU 100. The sensor output from the optical sensor 24 is input to the revolution speed difference detection unit 120. The revolution speed difference detection unit 120 counts the number of reflected light from the inner row of balls 20b received by the optical sensor 24, and calculates the revolution speed of the inner ball row from the number of reflected lights observed per second. To detect. The revolution speed difference detection unit 120 may detect the revolution speed of the inner ball train from the number of passages per second of the slits 23 of the cage 22b in the inner train.

  Further, the revolution speed difference detection unit 120 counts the number of reflected lights from the reflecting plate 25 of the outer row of cages 22a received by the optical sensor 24, and counts the number of reflected lights observed per second and the inner side. The revolution speed of the outer ball train is calculated from the revolution speed of the ball train. The revolution speed difference detection unit 120 obtains the difference between the revolution speed of the inner ball train and the revolution speed of the outer ball train thus obtained, and gives the obtained revolution speed difference to the load amount estimation unit 122.

  The revolution speed difference is an amount that changes depending on the load applied to the wheel, and the revolution speed difference-load table 124 stores the correspondence between the revolution speed difference and the load quantity. The load amount estimation unit 122 estimates the load amount corresponding to the revolution speed difference detected by the revolution speed difference detection unit 120 with reference to the revolution speed difference-load table 124.

  With reference to FIGS. 7 to 9 described in the first embodiment, a method for obtaining a load from a revolution speed difference by the wheel bearing rolling bearing unit 10 of the present embodiment will be described.

  Referring to FIG. 7, when no load is applied, the revolution diameter 70a connecting the rotation center 30a of the upper row of balls 20a and the rotation center 31a of the lower row of balls 21a is expressed as It changes as shown in 70a '. The revolution diameter 70a of the outer ball train at the time of no load and the revolution diameter 70a 'of the outer ball train at the time of the action of the bending moment M are almost the same. The same applies to the inner row of balls. When the bending moment M acts on the revolution diameter 70b connecting the rotation center 30b of the upper row of balls 20b and the rotation center 31b of the lower row of balls 21b when no load is applied, It changes as indicated by reference numeral 70b '. There is almost no difference between the revolution diameter 70b of the inner ball train when no load is applied and the revolution diameter 70b 'of the inner ball train when the bending moment M is applied.

  Therefore, the revolution speed of the outer row cage 22a and the revolution speed of the inner row cage 22b when the bending moment M is applied are substantially equal to the revolution speed at the time of no load, and the outer row cage 22a and the inner row cage 22b have the same revolution speed. There is almost no difference in the revolution speed of the cage 22b.

Referring to FIG. 8, the revolution diameter 70a connecting the rotation center 30a of the ball 20a on the outer row upper side and the rotation center 31a of the ball 21a on the lower row when no load is applied, the lateral force F _{H of} FIG. It changes as indicated by reference numeral 70a '. Lateral force F _H revolution diameter 70a of the outer ball row during the action of 'is shorter than the revolution diameter 70a of the outer ball row under no load. For the inner ball row, the revolution diameter 70b connecting the rotation center 30b of the ball 20b on the upper side of the inner row and the rotation center 31b of the ball 21b on the lower side of the inner row when no load is applied is indicated by a symbol 70b when the lateral force F _H acts. It changes as shown in '. Lateral force F _H revolution diameter 70b of the inner ball row during the action of 'is longer than the revolution diameter 70b of the inner ball row under no load.

Since the revolution diameter 70a ′ of the outer ball train is shortened when the lateral force F _H is applied, the revolution speed of the outer row cage 22a is slowed down. On the other hand, when the lateral force F _H is applied, the revolution diameter 70b ′ of the inner ball train becomes longer, and therefore the revolution speed of the cage 22b in the inner train becomes faster. Therefore, there is a significant difference between the revolution speed of the outer row cage 22a and the revolution speed of the inner row cage 22b.

Referring to FIG. 9, the revolution diameter 70a connecting the rotation center 31a of rotation center 30a and the outer column lower balls 21a of the outer column upper ball 20a at the time of no load, the vertical force F _H in the figure acts, It changes as indicated by reference numeral 70a '. Revolution diameter 70a of the outer ball row during the action of the vertical force F _H and revolution diameter 70a of the outer ball row under no load 'is no difference in most sizes. The same applies to the inner row of balls, and the revolution diameter 70b connecting the rotation center 30b of the upper row of balls 20b and the rotation center 31b of the lower row of balls 21b when no load is applied, when the vertical force F _H acts. , As indicated by reference numeral 70b ′. Revolution diameter 70b of the inner ball row during the action of the vertical force F _H and revolution diameter 70b of the inner ball row under no load 'is no difference in most sizes.

Accordingly, the revolution speed of the outer row cage 22a and the revolution speed of the inner row cage 22b when the vertical force F _H is applied are substantially equal to the revolution speed when there is no load, and the outer row cage 22a and the inner row are in the same direction. There is almost no difference in the revolution speed of the cage 22b.

From 7 to 9, the difference between the detectable significant during the revolution speed of the revolution speed and the inner row of retainer 22b of the retainer 22a of the outer column occurs when load is applied, the lateral force F _H acts It turns out that it is time. Therefore, the method of measuring the load by detecting the difference between the revolution speed of the outer row cage 22a and the revolution speed of the inner row cage 22b by the wheel bearing rolling bearing unit 10 of this embodiment is a lateral force. Particularly suitable for the measurement of F _H.

  Similar to the first embodiment, the magnitude of the load applied to the wheel is changed by experiment or simulation, and the difference in revolution speed between the outer ball train and the inner ball train is measured, and the relationship between the load and the revolution speed difference. Is acquired in advance. The revolution speed difference-load table 124 stores the correspondence relation between the revolution speed difference and the load amount obtained in this way.

  As in the first embodiment, since the correspondence between the load and the revolution speed difference may vary depending on the wheel speed, a plurality of revolution speeds storing the correspondence between the load and the revolution speed difference for different wheel speeds. More preferably, the difference-load table 124 is stored, and the load amount estimation unit 122 switches to the revolution speed difference-load table 124 according to the wheel speed and refers to it.

  Several modifications of the configuration of the wheel support rolling bearing unit 10 according to the second embodiment will be described. In the above description, the slits 23 are provided in the inner row cages 22b and the reflectors 25 are provided in the outer row cages 22a, and the light from the optical sensor 24 passing through the slits 23 is reflected by the reflector plates 25. However, as a first modification, the outer row cage 22a is not provided with the reflector 25, and the light passing through the slit 23 of the inner row cage 22b is reflected on the surface of the outer row ball 20a, The optical sensor 24 may receive the reflected light. In this case, it is preferable to increase the light receiving angle of the optical sensor 24 so that the optical sensor 24 can sufficiently receive the reflected light from the balls 20a in the outer row.

  Furthermore, as a second modification, a reflector other than the slits 23 may be provided in the inner row of cages 22b, and a reflector 25 may be provided in the outer row of cages 22a. In this case, the light emitted from the optical sensor 24 is reflected by the reflecting plate provided on the inner row holder 22b, and the optical sensor 24 receives the reflected light, so that the inner row holder 22b receives the reflected light. Revolution speed can be measured. Further, the light passing through the slit 23 of the inner row retainer 22b is reflected by the reflection plate 25 of the outer row retainer 22a, and the optical sensor 24 receives the reflected light, whereby the outer row retainer. The revolution speed of 22a can be measured. However, in this case, it is necessary to distinguish between the reflected light from the reflecting plate of the inner row cage 22b and the reflected light from the reflecting plate 25 of the outer row cage 22a. The reflection plate 25 of the outer row cage 22a is located farther from the optical sensor 24 than the reflection plate of the inner row cage 22b. As an example, the optical sensor 24 has a distance measuring function for measuring the distance to the object by receiving reflection of light applied to the object, and the distance function identifies a difference in the distance to the object. By doing so, it is discriminated whether the reflected light from the reflecting plate 25 of the outer row of retainers 22a or the reflected light from the reflecting plate of the inner row of retainers 22b.

  Further, as a third modified example, a reflector is provided in the inner row of cages 22b in addition to the slits 23, but the reflector 22 is not provided in the outer row of cages 22a and passes through the slits 23 of the inner row of cages 22b. A configuration may be adopted in which light is reflected by the outer rows of balls 20a. The operation in this case is the same as that of the second modification.

  Further, as a fourth modification, a first optical sensor for measuring the revolution speed of the inner row cage 22b and a second optical sensor for measuring the revolution speed of the outer row cage 22a may be provided separately. Good. As described in the first embodiment, as an example, the first optical sensor is installed in the cylindrical portion 17 and the second optical sensor is installed in the outer ring 18. In this case, the slits 23 are not required in the inner row cages 22b, and the inner row cages 22b are provided with a reflector, and the light emitted from the first optical sensor is reflected by the reflectors of the inner row cages 22b. And the first optical sensor receives the reflected light to measure the revolution speed of the cage 22b in the inner row. Similarly, in the outer row retainer 22a, the light irradiated from the second optical sensor is reflected by the reflecting plate of the outer row retainer 22a, and the second optical sensor receives the reflected light. The revolution speed of the cage 22a is measured. In this case, the ECU 100 determines the difference between the revolution speed of the inner row of cages 22b measured by the first optical sensor and the revolution speed of the outer row of cages 22a measured by the second optical sensor, and calculates the acting load. Ask.

  As described above, according to the wheel-supporting rolling bearing unit 10 of the present embodiment, the reflected light from the reflection plate of the double row bearing ball cage is obtained using a non-contact sensor such as an optical sensor. Is detected and the change in the revolution speed of the double row cage is detected, the magnitude of the load applied to the wheels during traveling of the vehicle can be accurately measured.

  The present invention has been described above based on the embodiment. It is to be understood by those skilled in the art that the embodiments are exemplifications, and various modifications are possible for the combination of each component, and such modifications are within the scope of the present invention.

  In the wheel support rolling bearing unit 10 of the first embodiment, the double-row angular contact ball bearing is used. However, when the load direction is not identified, a single-row angular contact ball bearing may be used. The magnitude of the load can be measured from the deviation of the rotation center of the ball.

  In the wheel support rolling bearing unit 10 according to the first embodiment, the movement speeds of the surfaces of the outer and inner rows of balls 20a and 20b and the deviation of the rotation center are detected by the optical sensors 24a and 24b. It is also possible to calculate the revolution speed of the balls 20a and 20b from the number of times of detection of the peak speed per second by counting the number of times the peak of the moving speed is detected. The optical sensors 24a and 24b can also directly detect the revolution speed of the cages 22a and 22b by identifying the irregularities on the surfaces of the cages 22a and 22b in the outer row and the inner row. Therefore, in the configuration of the first embodiment, the method of measuring the load from the difference in revolution speed between the outer row cage 22a and the inner row cage 22b described in the second embodiment can also be adopted. Therefore, in the configuration of the first embodiment, it is possible to further improve the load measurement accuracy by combining the method of measuring the load from the deviation of the rotation center and the method of measuring the load from the difference in revolution speed.

  In the wheel support rolling bearing unit 10 of the second embodiment, only one optical sensor 24 is provided, but a plurality of annular sensors are provided around the bearing shaft 11 to detect the revolution speed of the ball train at different positions. May be. By increasing the number of optical sensors 24, the load measurement accuracy can be further improved.

It is a figure which shows the structure of the rolling bearing unit for wheel support which concerns on Embodiment 1. FIG. FIG. 2A is a diagram for explaining an installation location of the optical sensor for observing the outer sphere in FIG. 1, and FIG. 2B is for observing the inner sphere in FIG. It is a figure explaining the installation location of this optical sensor. 1 is a diagram illustrating a configuration of an ECU according to Embodiment 1. FIG. It is a figure explaining the principle of the load measurement by the rolling bearing unit for wheel support of FIG. FIG. 5A is a diagram for explaining the speed observed by the optical sensor of FIG. 1 when no load is applied, and FIG. 5B is the image observed by the optical sensor of FIG. 1 when a load is applied. It is a figure explaining speed. It is a figure explaining the direction of the load which acts on the rolling bearing unit for wheel support of FIG. It is a figure explaining the shift | offset | difference of the rotation center of the ball | bowl of an outer row | line and the ball | bowl of an inner row | line upper and lower when the bending moment of FIG. 6 acts. It is a figure explaining the shift | offset | difference of the rotation center of the ball | bowl of an outer row | line at the time of the lateral force of FIG. It is a figure explaining the shift | offset | difference of the rotation center of the upper and lower balls of the outer row and the upper and lower balls of the inner row when the vertical force of FIG. 6 is applied. The direction in which the rotation centers of the balls on the upper side of the outer row, the lower side of the outer row, the upper side of the inner row, and the lower side of the inner row shift when the bending moment, lateral force, and vertical force in FIG. FIG. It is a figure which shows the structure of the rolling bearing unit for wheel support which concerns on Embodiment 2. FIG. It is a figure explaining the structure of the holder | retainer of the outer row | line | column of FIG. 10, and the holder | retainer of an inner row | line. FIG. 3 is a diagram showing a configuration of an ECU according to a second embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Rolling bearing unit for wheel support, 11 Bearing shaft, 12 Hub body, 13 Hub unit, 14 Flange, 16 Stud, 17 Cylindrical part, 18 Outer ring, 19 Inner ring, 20 Ball, 22 Cage, 23 Slit, 24 Optical sensor , 25 reflector, 30 center of rotation, 40 observation points, 62 observation trajectory, 70 revolution diameter, 100 ECU, 102 speed deviation detection unit, 104 load amount estimation unit, 106 speed deviation-load table, 108 rotation center deviation direction detection unit 110 load direction determination unit, 112 load direction determination table, 120 revolution speed difference detection unit, 122 load amount estimation unit, 124 revolution speed difference-load table.

Claims (9)

A wheel support hub unit comprising a plurality of rolling elements and a rolling member comprising a holding body for holding the plurality of rolling elements;
A load measuring device for measuring the load acting on the wheel,
The load measuring device is
A rolling element trajectory change detector for detecting an amount related to a change in the rotational trajectory of the rolling element;
A rolling bearing device, comprising: a load amount estimating unit that estimates a load amount acting on a wheel from a detected amount related to a change in a rotation trajectory of the rolling element. The rolling element trajectory change detection unit detects a moving speed of the surface of the rolling element as an amount related to a change in the rotational trajectory of the rolling element,
The load measuring device further includes a speed deviation detection unit that detects a deviation in which the moving speed of the surface of the rolling element deviates from the revolution speed of the holding body,
The rolling bearing device according to claim 1, wherein the load amount estimation unit estimates the load amount from the detected deviation. The rolling members are provided in a double row in the axle direction,
The rolling element trajectory change detection unit detects an amount related to a change in the rotational trajectory of the rolling element of the rolling members in each row,
The load measuring device further includes a load direction determination unit that determines a direction of a load acting on a wheel from a combination of amounts related to changes in the rotation trajectory detected for the rolling elements in each row. The rolling bearing device according to 1 or 2. The rolling element trajectory change detection unit detects an amount related to a change in the rotational trajectory of the rolling element at a vertical or horizontal position when viewed from the axle direction;
The load measuring device further includes a load direction determination unit that determines a direction of a load acting on a wheel from a combination of amounts related to a change in the rotation trajectory detected with respect to the rolling elements at the vertical and horizontal positions. The rolling bearing device according to claim 1 or 2, characterized by the above. The load measuring device further includes a rotation center deviation direction detection unit that detects a direction in which the rotation centers of the plurality of rolling elements are shifted based on a detection result by the rolling element trajectory change detection unit,
5. The rolling bearing device according to claim 3, wherein the load direction determination unit determines the direction of the load from a combination of shift directions of the rotation centers detected for a plurality of the rolling elements. 6. The rolling members are provided in a double row in the axle direction,
The rolling element trajectory change detection unit detects the revolution speed of the rolling elements in each row as an amount related to a change in the rotational trajectory of the rolling members of the rolling members in each row,
The rolling bearing device according to claim 1, wherein the load amount estimation unit estimates the load amount from a difference in revolution speed of the rolling elements detected in each row.   7. The rolling element trajectory change detection unit detects a revolution speed of the rolling elements in each row by receiving reflected light of light irradiated on the rolling element or the holding body. The rolling bearing device described in 1. The holding bodies in one row are provided with slits for allowing the irradiated light to pass through, and the holding bodies in the other row are provided with a reflector for reflecting the irradiated light,
The rolling element trajectory change detection unit receives reflected light that has passed through the slits of the holders in one row and is reflected from the reflecting plate of the holders in the other row. The rolling bearing device according to claim 7, wherein a revolution speed of the rolling element is detected.   The said rolling member is an angular bearing comprised so that the said rolling element might contact an inner ring track and an outer ring track at a predetermined angle with respect to a radial direction, It is any one of Claim 1 to 8 characterized by the above-mentioned. The rolling bearing device described.

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