JP2008008462A - Rolling bearing device for wheels - Google Patents

Abstract

Provided is a rolling bearing device for a wheel which can prevent a sensor from being damaged or not functioning as a sensor due to vibration, and can prevent a sensor circuit from being short-circuited due to condensation.
A cylindrical fixed race ring fixed to a vehicle body side, a rotary race ring rotatably inserted into the fixed race ring, and a roll raceway disposed between these race rings. A rolling bearing device for a wheel comprising a double row rolling element. An annular sensor housing having a plurality of displacement sensors in the circumferential direction for detecting a gap with the outer peripheral surface of the vehicle inner side end of the rotating raceway is attached to the vehicle inner side end of the fixed raceway. The displacement sensor is covered with a synthetic resin or a rubber material and integrated with the sensor housing.
[Selection] Figure 1

Description

  The present invention relates to a wheel rolling bearing device. More specifically, the present invention relates to a wheel rolling bearing device that is used in a vehicle such as an automobile and includes a sensor that obtains information from the wheel of the vehicle.

2. Description of the Related Art In recent years, in automobiles, various information such as loads acting on wheels and the number of rotations of wheels has been required in order to perform operation control during traveling. In order to obtain such information, it has been proposed to provide a sensor in a wheel rolling bearing device to which a vehicle wheel is attached.
Conventionally known as such a rolling bearing device for a wheel is a cylindrical fixed raceway fixed to the vehicle body side, and a rotary raceway provided on the radial inner side of the fixed raceway and to which a wheel is attached. There is a bearing device provided with a ring and a double row rolling element provided between these raceways so as to be freely rollable. In this bearing device, the above-mentioned sensor is provided on a fixed raceway, Some are configured to obtain information on the rotating raceway (see, for example, Patent Document 1).

In the bearing device described in Patent Document 1, a through-hole penetrating in the radial direction is formed in the fixed race, and a sensor is inserted and fixed in the through-hole. And the measurement part of a sensor is made to oppose the outer peripheral surface of a rotation raceway, and the sensor acquires the information on a rotation raceway.
However, in the rolling bearing device for a wheel described in Patent Document 1, it is necessary to form a plurality of through holes in the fixed race ring in order to provide a plurality of sensors on the fixed race ring. In this case, another drilling operation is required in the manufacturing process of the fixed raceway, and a sensor needs to be attached to each through-hole, which complicates the assembly operation. Further, the gap adjustment between the sensor and the rotating raceway is necessary for each sensor, and there is a problem that the number of assembling steps increases.

Therefore, the present applicant has previously proposed a rolling bearing device for a wheel that can be easily assembled even if it has a plurality of sensors, and can be easily assembled (Japanese Patent Application No. 2005-266482, hereinafter). The first proposal).
The rolling bearing device for a wheel according to the first proposal has a cylindrical fixed raceway fixed to the vehicle body side, and is rotatably inserted into the fixed raceway and has a wheel mounting portion on the outer side. A rolling bearing device for a wheel including a rotating raceway and a double row rolling element provided between the raceways so as to be freely rollable, and an outer peripheral surface of an inner side end of the rotating raceway A case member having a plurality of displacement sensors for detecting a gap with respect to the circumferential direction at predetermined intervals is provided, and the case member is attached to an inner side end of the fixed raceway.

And according to this structure, since the case member has a plurality of displacement sensors and this case member is attached to the inner side end of the fixed raceway, the displacement sensors are individually attached to the fixed raceway. There is no need to provide a through hole for the sensor in the fixed race. Furthermore, by attaching the case member to the fixed raceway, each displacement sensor is positioned with respect to the outer peripheral surface of the inner end portion of the rotary raceway, so that assembly is facilitated.
Further, the displacement sensor can detect a change in the gap with the outer peripheral surface of the inner side end of the rotating raceway caused by the radial load acting on the wheel. Further, when the rotating raceway is displaced so as to be inclined with respect to the fixed raceway (when a moment is applied), the change in the gap becomes larger at the inner side end than the central portion in the axial direction. Detection accuracy can be improved because the displacement sensor measures the outer peripheral surface of the side end portion.

  On the other hand, in the rolling bearing device for a wheel according to the first proposal, another displacement sensor for detecting the axial displacement at the shaft end surface of the rotating raceway is provided to obtain the axial translational load. A case member that closes the inner end is added. If a displacement sensor that detects the axial displacement at the shaft end face of the rotating raceway is added in this way, it can be used in a bearing device for a driven wheel in which the shaft end face of the rotating raceway is a free end. Sensors other than load measurement, such as ABS sensors, cannot be used in a bearing device for a drive wheel in which a constant velocity joint of a drive shaft is connected to the shaft end surface of the wheel. Therefore, the present applicant has further proposed a wheel rolling bearing device in which the other displacement sensor can be omitted (Japanese Patent Application No. 2005-322651. 2).

The rolling bearing device for a wheel according to the second proposal includes a fixed bearing ring having a fixed portion with respect to the vehicle body side, and a rotating race ring having a wheel mounting portion arranged coaxially with respect to the fixed track ring. A plurality of rolling elements provided between the two race rings so as to be rotatable relative to each other, and a physical quantity that changes in accordance with the displacement of the peripheral side surface of the rotary race ring. A sensor-equipped rolling bearing device comprising: a sensor device provided on the fixed raceway, wherein the sensor device has the physical quantity at a position separated in the axial direction on a peripheral side surface of the rotary raceway. First and second sensor members are provided for detection, respectively, and connected to a control device having a calculation function for calculating a moment load acting on the wheel based on a difference between detection values detected by the sensor members. To have.
And according to this structure, the 1st sensor member and the 2nd sensor member which detect the physical quantity which changes with the displacement of the circumference side of a rotation raceway are in the position where it separated in the direction of an axis in the circumference side of a rotation raceway. Since the physical quantity is detected, the moment load acting on the wheel can be calculated by the control device based on the difference between the detection values detected by the sensor members.

JP 2002-340922 A (see FIG. 1)

However, in the embodiment of the wheel rolling bearing device according to the first or second proposal, the sensor may be damaged by vibration during use, or the sensor function may be hindered by loosening of the sensor. There is.
Moreover, there is a possibility that the sensor may not function due to a short circuit of the sensor circuit that constitutes the sensor due to moisture due to condensation.
The present invention is an improvement to the wheel rolling bearing device according to the first or second proposal previously proposed by the applicant, and the sensor may be damaged by the vibration or may not function as the sensor. It is an object of the present invention to provide a rolling bearing device for a wheel that can prevent the sensor circuit from being short-circuited due to condensation and increase the reliability of the sensor.

The wheel rolling bearing device of the present invention includes a cylindrical fixed race ring fixed to the vehicle body side, a rotary race ring that is rotatably inserted into the fixed race ring, and a rolling ring between these race rings. A rolling bearing device for a wheel comprising a double-row rolling element arranged freely,
An annular sensor housing having a plurality of displacement sensors in the circumferential direction for detecting a gap with the outer peripheral surface of the vehicle inner side end of the rotating raceway is attached to the vehicle inner side end of the fixed raceway. The displacement sensor is covered with a synthetic resin or a rubber-based material and integrated with the sensor housing.

  In the wheel rolling bearing device of the present invention, since the displacement sensor is covered with a synthetic resin or a rubber-based material and integrated with the sensor housing, the wiring and parts constituting the sensor can be firmly fixed. It is possible to effectively prevent the wiring from being disconnected or the components from being damaged due to vibration. In addition, it is possible to prevent the displacement sensor from being loosened due to vibrations and causing the backlash of the displacement sensor to hinder the function of the sensor. Furthermore, since it is covered with a synthetic resin or a rubber-based material, it is possible to prevent moisture such as condensation from entering the sensor circuit in the displacement sensor and short-circuiting the sensor circuit. In this way, the reliability of the sensor can be improved by preventing the occurrence of defects due to vibration and condensation. Further, since the sensor is completely shielded, it is possible to prevent foreign matters such as dust from entering the sensor while the bearing device is being transported.

  Each of the plurality of displacement sensors may include a first displacement sensor and a second displacement sensor that detect the gaps at positions separated in the axial direction on the peripheral side surface of the rotating raceway. In this case, since the first sensor member and the second sensor member detect a gap at a position separated in the axial direction on the peripheral side surface of the rotating raceway wheel, the wheel is based on the difference between the detection values detected by each sensor member. It is possible to calculate the moment load acting on the. In this way, since the moment load of the wheel can be obtained only by the first and second sensor members that detect the physical quantity that changes with the displacement of the peripheral side surface of the rotating raceway, in order to measure the moment load There is no need to add a sensor for detecting the axial displacement of the shaft end surface of the rotating raceway. For this reason, it is applicable also to the bearing apparatus for drive wheels to which the constant velocity joint of a drive shaft is connected.

  The vehicle inner side end of the sensor housing is preferably sealed with an inner side sealing device. According to this configuration, the lid member that closes the vehicle inner side end of the sensor housing in each of the first and second proposed embodiments can be omitted. Therefore, it can be easily applied not only to the driven wheel but also to the driving wheel while ensuring the sealing performance of the displacement sensor.

  It is preferable that a vehicle outer side end portion of the sensor housing is sealed with an outer side sealing device. According to this configuration, it is possible to prevent the grease in the bearing from flowing into the sensor housing and damage the bearing due to poor lubrication, thereby extending the life of the bearing.

  According to the rolling bearing device for a wheel of the present invention, it is possible to prevent the sensor from being damaged or not functioning as a sensor due to vibration, and to prevent the sensor circuit from being short-circuited due to condensation.

Embodiments of a rolling bearing device for a wheel (hereinafter also simply referred to as a bearing device) of the present invention will be described below in detail with reference to the accompanying drawings.
FIG. 1 is an axial sectional view of an embodiment of a bearing device of the present invention, and FIG. 2 is a partially enlarged view of the bearing device shown in FIG. 1-2 and FIGS. 3 to 6 described later, the right side is the vehicle inner side (the inside of the vehicle), and the left side is the vehicle outer side (the outside of the vehicle).

[Overall structure of bearing device]
As shown in FIG. 1, the bearing device H of the present embodiment includes a cylindrical outer ring 1, an inner shaft 2 that is rotatably inserted into the outer ring 1, and a vehicle inner of the inner shaft 2. An inner ring member 3 externally fitted to the side end portion, a sensor target 4 externally fitted to the vehicle inner side end portion of the inner ring member 3, and a plurality of rolling elements 5, 5 comprising a plurality of balls arranged in the circumferential direction. The double-row angular contact ball bearing portion is constituted by these. The balls in each row as the rolling elements 5 and 5 are held by the holder 6 at a predetermined interval in the circumferential direction. The bearing device H is a bearing device for a drive wheel, and is formed integrally with a saddle-shaped outer ring member of a constant velocity joint from the vehicle inner side in an insertion hole 2a formed in the inner shaft 2, although not shown. The formed shaft portion is spline-fitted.

  In this specification, the direction along the center line C of the bearing device H is defined as the y-axis direction, the horizontal direction perpendicular to the paper surface is defined as the x-axis direction, and is orthogonal to the y-axis direction and the x-axis direction. The vertical direction is defined as the z-axis direction. Accordingly, as shown in FIG. 17, the x-axis direction is the front-rear horizontal direction of the wheel, the y-axis direction is the left-right horizontal direction (axial direction) of the wheel, and the z-axis direction is the vertical direction.

  In the bearing device H of the present embodiment, the outer ring 1 is a fixed race that is fixed to the vehicle body side. On the other hand, the inner shaft 2, the inner ring member 3, and the sensor target 4 serve as a rotating raceway on the wheel side, and the double row rolling elements 5, 5 roll between the fixed raceway and the rotary raceway. It is movably interposed. Thereby, the fixed raceway and the rotary raceway are arranged coaxially with each other, and the rotary raceway is rotatable with the wheels (the tire and the tire wheel shown in FIG. 17) relative to the fixed raceway.

  The inner shaft 2 constituting the rotating raceway has a flange portion 7 extending outward in the radial direction on the vehicle outer side, and this flange portion 7 serves as a mounting portion for a wheel tire wheel or a brake disk. The tire wheel or the like is attached to the flange portion 7 with a mounting bolt (not shown). The inner ring member 3 is externally fitted to a step portion formed on the inner side of the inner shaft 2 on the vehicle inner side. The inner raceway surfaces 9 and 9 of the rolling elements 5 and 5 are formed on the outer peripheral surface of the inner shaft 2 and the outer peripheral surface of the inner ring member 3, respectively.

  The outer ring 1 constituting the fixed raceway includes a cylindrical main body cylinder portion 11 in which the outer raceway surfaces 10 and 10 of the rolling elements 5 and 5 are formed on the inner peripheral surface, and a radial direction from the outer peripheral surface of the main body cylinder portion 11. And a flange portion 12 extending outward. The flange portion 12 is fixed to a knuckle (not shown) of a suspension device that is a vehicle body side member, whereby the bearing device H is fixed to the vehicle body side.

The bearing device H of the present embodiment has a physical quantity that changes with the displacement of the outer peripheral side surface of the sensor target 4 provided on the rotating raceway (in this embodiment, the inductance that changes due to the gap with the outer peripheral side surface of the sensor target 4). ) And a sensor housing 16 for attaching the sensor device 14 to the outer ring 1 which is a fixed raceway ring. The sensor housing 16 is made of a short cylindrical tube member, and the tube member is made of a cylindrical metal member that is short in the axial direction. And in the opening part of the one end side (vehicle outer side), it fixes to the vehicle inner side edge part of the outer ring | wheel 1 so that it may become coaxial with the said outer ring | wheel 1 with the set screw 18. FIG.
The vehicle inner side end portion of the sensor housing 16 is sealed with a pack seal 50 which is an inner side sealing device, and foreign matter such as dust can be prevented from entering the sensor. The sensor housing 16 can also be fixed to the outer ring 1 by press-fitting the inner surface of the outer ring 1 without using the set screw 18.

[Structure of sensor device]
As shown in FIGS. 7 to 8, the sensor device 14 in the present embodiment detects a gap at a position separated in the axial direction on the outer peripheral side surface of the sensor target 4, respectively, and a first sensor member 21 and a second sensor member 22. And. In the present specification, regarding the sensor device 14 and the sensor target 4, “first” means the vehicle inner side, and “second” means the vehicle outer side.

  The first and second sensor members 21, 22 are inductance-type displacement sensors that detect a change in gap with the outer peripheral side surface of the sensor target 4 by a change in inductance, and are separated in the axial direction on the inner peripheral side of the sensor housing 16. In addition, a ring-shaped sensor core 23 attached in two rows and a plurality of displacement sensors 24 arranged at predetermined intervals in the circumferential direction of the sensor core 23 are provided. Each sensor core 23 is fixed to the flange portion 16a of the sensor housing 16 with a set screw or the like with a cylindrical spacer (not shown) interposed therebetween.

The displacement sensors 24 of the first and second sensor members 21 and 22 are provided at four positions, front and rear, and upper and lower, respectively, and gaps in the x-axis direction and the z-axis direction with the outer peripheral side surface of the sensor target 4 of the rotating track ring It is arranged so that a change can be detected.
That is, the first sensor member 21 on the vehicle inner side includes a first front sensor 24f and a first rear sensor 24r disposed before and after the rotating raceway, and a first upper sensor 24t respectively disposed above and below the rotating raceway. And a first lower sensor 24b. Further, the second sensor member 22 on the vehicle outer side also includes a second front sensor 24f and a second rear sensor 24r disposed before and after the rotating raceway, and a second upper sensor 24t respectively disposed above and below the rotating raceway. And a second lower sensor 24b.

  Each of these eight displacement sensors 24 (f, r, t, b) is connected in series to a pair of coil elements 27, 27 arranged in close proximity in the circumferential direction having an independent detection surface for the sensor target 4. It is configured by The pair of coil elements 27, 27 is configured by winding a coil around a pair of magnetic poles 28 protruding from the inner peripheral side of the sensor core 23. These magnetic poles 28 protrude inward in the radial direction from the sensor core 23, and are arranged so that the end surface (detection surface) inside the diameter faces the outer peripheral side surface of the sensor target 4 with a radial gap. Has been.

  As described above, in the bearing device H according to the present embodiment, the first and second sensor members 21 and 22 that are separated in the axial direction and have the four displacement sensors 24 arranged in the front-rear and top-bottom directions are integrated with the sensor housing 16. Therefore, all the displacement sensors 24 can be attached to the outer ring 1 simply by attaching the sensor housing 16 to the vehicle inner side end of the outer ring 1 when the bearing device H is assembled. it can. For this reason, it is not necessary to attach each displacement sensor 24 to the outer ring 1 individually, and it is not necessary to provide a through hole for mounting the sensor in the outer ring 1.

Further, by attaching the sensor housing 16 to the outer ring 1, the circumferential position and the radial position of each displacement sensor 24 with respect to the sensor target 4 of the rotating raceway are respectively positioned, so that the position of each displacement sensor 24 is adjusted. There is no need for mounting, and in this respect, the assembly of the bearing device H is extremely easy.
Further, each displacement sensor 24 incorporated in the sensor housing 16 has an inner side end of the rotating raceway whose deformation behavior with respect to an external force is larger than an axial center portion (portion close to the bearing center O shown in FIG. 1) of the rotating raceway. Since the gap associated with the deformation behavior of the sensor target 4 located in the part is detected, there is an advantage that the accuracy of detecting the gap is increased.

  Further, when the sensor housing 16 with the sensor is attached to the vehicle inner side end portion of the outer ring 1, the displacement sensor 24 is disposed at a position relatively far from the flange portion 12 of the outer ring 1, so that the flange portion There is also an advantage that a gap change can be detected with high accuracy in this respect.

  In the present embodiment, the sensor housing 16, the sensor core 23, the coil element 27, and the wiring substrate 40 disposed on the sensor core 23 and wiring the coil element and a lead wire for outputting a detection signal are provided. It is sealed (molded) with a thermosetting resin such as epoxy or acrylic, or a thermoplastic resin such as PPS, PA or ABS. In other words, the displacement sensor 24 is covered with the synthetic resin and integrated with the sensor housing 16. As a result, the wiring board 40 can be firmly fixed to the sensor core 23, and electrical elements on the wiring board 40 can be prevented from being damaged and the coil element 27 can be prevented from being disconnected due to vibration. In addition, it is possible to prevent the set screw that fixes the sensor core 23 to the sensor housing 16 from being loosened by vibrations, causing play in the sensor core 23 and the sensor not functioning. Further, since the wiring substrate 40 is sealed, it is possible to prevent the wiring from being short-circuited by moisture such as condensation. In place of the synthetic resin, the wiring board 40 and the like may be sealed (molded) with a rubber-based material.

  FIG. 9A shows an example of a gap detection circuit by the sensor device 14 in the present embodiment. As shown in the drawing, among the displacement sensors 24 of the sensor members 21 and 22, sensors (upper and lower sensors in FIG. 9) 24t and 24b facing each other in the vertical direction are connected to the oscillator 30, respectively. An alternating current having a constant period is supplied from the oscillator 30 to the sensors 24t and 24b. A synchronous capacitor 31 is connected in parallel to each of the sensors 24t and 24b.

  In this embodiment, the output voltage (detection value) from each of the sensors 24t and 24b is determined by the differential amplifier 32 to obtain the output voltage (detection value) corresponding to the vertical displacement. Try to remove the temperature drift. Although not shown, the temperature drift is removed by taking the difference with the differential amplifier in the same manner as described above for the sensors facing each other in the horizontal direction.

By the way, in the inductance type displacement sensor 24, the inductance of the coil is L, the area of the detection surface is A, the magnetic permeability is μ, the number of turns of the coil is N, and the distance (gap) from the detection surface to the sensor target 4 is d. Then, the following equation (a) is established.
L = A × μ × N ² / d (a)
Accordingly, when the gap d to the sensor target 4 changes, the inductance L of the displacement sensor 24 changes and the output voltage changes. By detecting this change in output voltage, the sensor sensor is detected from the detection surface of the displacement sensor 24. A radial gap to the target can be detected.

  In this embodiment, since one displacement sensor 24 is configured by connecting a pair of coil elements 27 having independent detection surfaces with respect to the sensor target 4 in series, FIG. 9B shows. As described above, the magnetic flux density generated is higher than that in the case where one displacement sensor 24 is constituted by one coil element 27, and thereby the detection sensitivity of the gap with the sensor target is further improved. .

[Structure of sensor target]
As shown in FIGS. 1 and 2, the sensor target 4 is formed of a cylindrical member that is externally fitted and attached to a vehicle inner side end portion of the inner ring member 3. On the outer peripheral side surface of the sensor target 4, there are a first detected portion 34 facing the detection surface (tip surface of the magnetic pole 28) of the first sensor member 21 on the vehicle inner side, and a second sensor member 22 on the vehicle outer side. A second detected portion 35 that faces the detection surface is provided. In the present embodiment, these detected portions 34 and 35 are configured by first and second step portions formed along the circumferential direction of the sensor target 4.

As shown in FIG. 2B, the first step 34 on the vehicle inner side is arranged such that the end surface 34a on the vehicle outer side is located near the center of the detection surface A1 of the first sensor member 21, The second step portion 35 on the vehicle outer side is arranged so that the end surface 35 a on the vehicle inner side is located near the center of the detection surface A <b> 2 of the second sensor member 22.
For this reason, if the sensor target 4 of the rotating raceway is displaced by a distance δ toward the vehicle outer side in the axial direction, for example, the axial wrap between the first sensor member 21 and the first step portion 34 is performed on the vehicle inner side. The length increases, the detected value of the gap by the first sensor member 21 increases, and on the vehicle outer side, the axial wrap length between the second sensor member 22 and the second step portion 35 decreases, The detected value of the gap by the two sensor members 22 decreases.

Similarly, if the sensor target 4 of the rotating raceway is displaced by the distance δ toward the vehicle inner side in the axial direction, the detected value of the gap by the first sensor member 21 on the vehicle inner side decreases, and the second on the vehicle outer side. The detection value of the gap by the sensor member 22 increases.
Thus, the sensor target 4 in the present embodiment causes a difference in the detection values detected by the first and second sensor members 21 and 22 when the rotating raceway is displaced in the same direction in the axial direction. A pair of step portions 34 and 35 separated in the axial direction are provided on the outer peripheral side surface.

Further, as described above, these step portions 34 and 35 change the detected values detected by the sensor members 2 and 22 in the positive and negative directions when the rotating raceway is displaced in the same direction in the axial direction. An axial position with respect to the sensor side is set.
Accordingly, as is apparent from the calculation method of the detection value in the control device described later, the rotation is obtained by taking the difference between the detection value of the first sensor member 21 on the vehicle inner side and the detection value of the second sensor member 22 on the vehicle outer side. The detection value with respect to the unit translation amount in the axial direction of the raceway ring is amplified, thereby increasing the detection sensitivity of the axial displacement of the entire sensor device.
Each displacement sensor 24 constituting the first and second sensor members 21 and 22 is connected to a control device including, for example, an ECU on the vehicle body side via a signal line. The output voltage (detected value) obtained from each sensor is calculated by the calculation method described below in the control device, whereby the moment load and the translation load acting on the wheel in each direction are obtained.

[Structure of sealing device]
The pack seal 50 which is an inner side sealing device includes a seal core 51 fixed to the inner peripheral surface of the flange portion 16 a of the sensor housing 16 and a seal fixed to the outer peripheral surface of the vehicle inner side end of the sensor target 4. A core metal 52 and a rubber seal body 53 fixed to the surface of the seal core metal 51 facing the seal core metal 52 are configured. The tip of the seal body 53 is a seal core metal 52. The inside of the bearing is hermetically sealed by being pressed.

[Calculation method for each load]
Hereinafter, the load calculation method performed by the control device will be described with reference to FIGS. FIG. 15 is a block diagram showing a calculation method in the control device.

[Definition of direction and sensor detection value]
As shown in FIG. 17, the front-rear horizontal direction of the wheel is defined as the x-axis direction, the left-right horizontal direction (axial direction) of the wheel is defined as the y-axis direction, and the vertical direction of the wheel is defined as the z-axis direction.
Further, as shown in FIG. 10, the subscript “i” is used for the detected value of the sensor on the vehicle inner side (first sensor member 21), and the subscript is used for the sensor on the vehicle outer side (second sensor member 22). Use “o”. Further, the detection value of the front sensor is defined as “f (front)”, the detection value of the rear sensor is defined as “r (rear)”, and the detection value of the upper sensor is defined as “t (top)”. The detection value of the lower sensor is defined as “b (bottom)”.

Accordingly, the detection values of a total of eight sensors provided in the first and second sensor members 21 and 22 are defined as follows.
f _i : Detection value of the first front sensor r _i : Detection value of the first rear sensor t _i : Detection value of the first upper sensor b _i : Detection value of the first lower sensor f _o : Detection value of the second front sensor r _o : detection value of the second rear sensor t _o : detection value of the second upper sensor b _o : detection value of the second lower sensor

[Independent variable (sFy) corresponding to translational load Fy in the y-axis direction]
As shown in FIG. 11B, when a translational load Fy in the y-axis direction is applied to the wheel, the rotating raceway is displaced in the direction of the load, and the positions of the stepped portions 34 and 35 are in the axial direction. Shift. Therefore, as described above, the detection value of each sensor in the vehicle inner side (the output voltage in this _{embodiment) f i, r i, t} i, b i is either with increasing amount of axial movement δ The detected values f _o , r _o , t _o , and b _o of the sensors on the vehicle outer side all decrease as the axial movement amount δ increases.

Therefore, as shown in FIG. 11B, sFy calculated by the following equation (1) is adopted as an independent variable corresponding to the translational load Fy in the y-axis direction (see the calculation block B1 in FIG. 15).
sFy = (f _i + r _i + t _i + b _i ) − (f _o + r _o + t _o + b _o ) (1)
Thus, by taking the difference between the detection value of each sensor on the vehicle inner side and the detection value of each sensor on the vehicle outer side, sFy with respect to the unit translation amount in the axial direction of the rotating raceway ring is amplified. The detection sensitivity of the axial displacement as the entire apparatus 14 can be increased.

[X-axis direction displacement and z-axis direction displacement]
As shown in the calculation block B2 in FIG. 15, in the x-axis direction, the detected value of the displacement in the x-axis direction is determined by the difference between the detected value f of the front sensor and the detected value r of the rear sensor. The difference between the detection value t of the sensor and the detection value b of the lower sensor is used as a detection value for displacement in the z-axis direction.
Since the output of the front and rear sensors and the output of the upper and lower sensors are affected by the temperature in the same direction by the same amount, the temperature drift is eliminated by taking the difference as described above.

In the present embodiment, since the displacement sensors 24 are arranged on the vehicle inner side and the outer side, as shown below, the detected value of the displacement in the x-axis direction and the z value at the respective positions on the vehicle inner side and the vehicle outer side. A detection value of the axial displacement is obtained.
Detected value of displacement in the x-axis direction on the vehicle inner side x _i = f _i −r _i
Detected value of displacement in the z-axis direction on the vehicle inner side z _i = −t _i + b _i
Detection values of the x-axis direction displacement of the vehicle outer side x _o = _{f o} -r _o
Detected value of displacement in the z-axis direction on the vehicle outer side z _o = −t _o + b _o
[Independent variable (sMz) corresponding to moment load Mz around z-axis]
Next, as shown in FIG. 12, a pure moment state in which only the moment load Mz about the z-axis acts is assumed.

In this case, the axial distance from the bearing center O to the detection position of the vehicle inner side sensor (first sensor member 21) is L _i , and from the bearing center O to the detection position of the vehicle outer side sensor (second sensor member 22). If the axial distance is L _o , the detected value corresponding to the moment load Mz around the z axis can theoretically be obtained by mz calculated by the following equation, and this mz is sufficiently small in θ. it should be consistent with the x _i in the case.
mz = L _i × tan θ
= L _i × tan ((x _i -x _o ) / (L _i -L _o ))
However, actually, since the step portions 34 and 35 are formed on the sensor target, mz does not match x _i as shown in FIG. FIG. 14 (a), when an acting only z axis of the moment load Mz, a line graph showing the relationship between the detection value of the Mz and mz and x _i, thus, mz and x The straight line graphs of the detected values of _i do not match the slopes.

Therefore, as shown in FIG. 14C, in order to make these inclinations coincide with each other, a correction coefficient kz obtained by dividing the inclination of the _xi line by the inclination of the mz line is introduced. Therefore, as shown in the following equation (2), by multiplying the above-described mz by the correction coefficient kz, an independent variable sMz corresponding to the moment load Mz around the z-axis is obtained (calculation blocks B3 and B4 in FIG. 15). reference). The minus (−) on the right side is for making the sign coincide with other independent variables (such as sFy and sMx described later).
sMz = −mz × kz (2)

[Independent variable (sMx) corresponding to moment load Mx around x-axis]
The x-axis direction and the z-axis direction have a relationship obtained by coordinate conversion by 90 degrees. Therefore, the independent variable sMx corresponding to the moment load Mx around the x axis can be calculated by the following equation (3) based on the same concept as in the case of sMz.
sMx = mx × kx (3)
Incidentally, kx in the formula (3) is a correction factor introduced in the same spirit as kz, the slope of z _i straight is a correction coefficient obtained by dividing the slope of mx line (FIG. 14 (b) and (Refer FIG.14 (c)).

[Independent variable (sFz) corresponding to the translational load Fz in the z-axis direction]
[Independent variable (sFx) corresponding to translation load Fx in the x-axis direction]
Next, as shown in FIG. 13, it is assumed that the translational load Fx in the x-axis direction acts together with the moment load Mz around the z-axis.
In this case, the detected value x _{i of the} displacement in the x-axis direction on the inner side includes the component of the independent variable sMz corresponding to the moment load Mz around the z-axis and the independent variable sFx corresponding to the translational weight Fx in the x-axis direction. Contains ingredients. Therefore, the independent variable sFx corresponding to the translational weight Fx in the x-axis direction can be obtained by subtracting sMz from x _i .
This also applies to the case of sFz, which is an independent variable corresponding to the translation load Fz in the z-axis direction.

Therefore, the independent variable sFz due to the translation load Fz in the z-axis direction and the independent variable sFx due to the translation load Fx in the x-axis direction can be calculated by the following equations (4) and (5), respectively (FIG. 15). (See calculation block B4).
sFz = z _i −mx × kx (4)
sFx = x _i −mz × kz (5)
FIG. 16 shows the independent variables sFx, sFy, sFz, sMx, and sMz obtained by the equations (1) to (5) described above, and Fx, Fy, Fz, Mx, and Mz that are actual loads acting on the wheels. It is a matrix figure showing the correspondence of these.

That is, Fx, Fy, Fz, Mx and Mz actually loaded on the wheel are input, and the independent variables sFx, sFy, sFz, sMx and sMz obtained by the equations (1) to (5) are output, It is a matrix of straight line graphs between these variables.
As shown in the matrix diagram of FIG. 16, only sFx is a straight line graph having a slope with respect to Fx, and other Fy, Fz, Mx, and Mz have no reaction, and similarly, Only the diagonal part is a straight line graph. Therefore, these five independent variables sFx, sFy, sFz, sMx and sMz are in a linearly independent relationship with the five component forces Fx, Fy, Fz, Mx and Mz which are actual loads acting on the wheels.
For this reason, once these independent variables sFx, sFy, sFz, sMx and sMz are obtained, by solving the five-way simultaneous linear equations with five loads Fx, Fy, Fz, Mx and Mz acting on the wheels as unknowns, The respective loads Fx, Fy, Fz, Mx and Mz can be calculated.

In the present embodiment, a control device comprising an ECU or the like incorporates the above-described equations (1) to (5) and an arithmetic circuit (hardware) or a control program (software) that solves the quinary simultaneous linear equations. Yes. Therefore, based on the eight detected values f _i , r _i , t _i, b _i , f _o , r _o , t _o and b _o by each sensor, the actual loads Fx, Fy, Fz, Mx and Mz can be determined.

  FIG. 3 is an axial sectional view of another embodiment of the bearing device of the present invention, and FIG. 4 is a partially enlarged view of the bearing device shown in FIG. In the present embodiment, as shown in FIG. 4, the point that the seal core 52 on the sensor target 4 side in the pack seal 50 is formed integrally with the sensor target 4 is shown in FIGS. It is different from the form. Therefore, in FIGS. 3 to 4, elements or configurations common to the embodiment shown in FIGS. 1 and 2 are denoted by the same reference numerals, and description thereof is omitted for the sake of simplicity.

In the present embodiment, one end portion of the sensor target 4 is press-molded to form the seal metal core 52, and the displacement sensor 24 is formed using the sensor target 4 provided on the vehicle inner side end portion of the rotating raceway. In the configuration for detecting the gap, the structure can be simplified by reducing the number of parts.
The bearing device of the present invention can be applied not only to driving wheels as shown in FIGS. Further, in the present invention, the inner side sealing device is not limited to the pack seal described above, and other sealing mechanisms may be appropriately employed as long as the configuration can prevent foreign matter from entering the sensor device. Can do. For example, a single seal, a seal with a magnetic pulser, a pack seal with a built-in ABS sensor, and the like can be appropriately employed. Furthermore, the outer diameter surface of the inner ring member (see FIG. 19 to be described later) or the CVJ outer diameter surface can be directly used as a detected surface without using a separate sensor target 4. The inner side sealing device is inserted and disposed between the sensor housing 16 and the outer diameter surface of the inner ring member.

FIG. 5 is a partial cross-sectional explanatory view of still another embodiment of the bearing device of the present invention, and FIG. 6 is a partial cross-sectional explanatory view of another embodiment. 5 to 6, elements or configurations common to the above-described embodiment shown in FIGS. 1 and 2 are denoted by the same reference numerals, and description thereof is omitted for simplicity.
In the bearing device shown in FIGS. 1 to 4 and the bearing device according to the first or second proposal of the present applicant, no seal or the like is disposed in the vicinity of the rolling element on the vehicle inner side. In the bearing device shown in Fig. 4, the pack seal (inner side seal device), and in the bearing device according to the first or second proposal, the inside of the bearing is sealed by a lid member to prevent the entry of foreign matter such as dust and water from the outside. is doing. However, since there is no seal or the like in the vicinity of the rolling element on the vehicle inner side, the grease filled in the bearing may flow out to the sensor side, and the bearing may be damaged due to poor lubrication.

  Therefore, in the bearing device according to the present embodiment, the vehicle outer side end portion of the sensor housing 16 is sealed by the outer side sealing device to prevent the grease from flowing out. In the embodiment shown in FIG. 5, the outer side sealing device includes a slinger 60 having a substantially L-shaped cross section fixed to the inner peripheral surface of the sensor housing 16 near the vehicle outer side end, It is comprised with the rubber-made sealing body 61 fixed to the front-end | tip of the part 60a extended to radial inside. By providing such a sealing device, the grease filled in the bearing can be prevented from flowing out to the sensor side, and as a result, the bearing can be prevented from being damaged due to poor lubrication and the life of the bearing can be prevented. Can be extended.

The open end of the sensor housing 16 is closed by a lid member 62, thereby preventing foreign matters such as dust and water from entering the bearing.
FIG. 6 shows another embodiment of the bearing device of the present invention. In this embodiment, the length of the portion 60a extending inward in the radial direction of the slinger 60 is longer than that of the embodiment shown in FIG. The seal body 61 at the front end is omitted so that the front end is opposed to the outer peripheral surface 3a of the inner ring member 3 leaving a slight gap. Also in the present embodiment, the gap between the slinger tip and the outer peripheral surface 3a of the inner ring member 3 is made extremely small, so that the grease filled in the bearing is prevented from flowing out to the sensor side. As a result, it is possible to extend the life of the bearing by avoiding damage to the bearing due to poor lubrication.

  Note that the outer-side sealing device is not limited to the above-described one, and other sealing mechanisms can be appropriately employed as long as the structure can prevent the grease from flowing out to the sensor device. Further, the slinger 60 may be formed integrally with the sensor housing 16 in the same manner as the seal metal core in FIG. 4, whereby the number of parts can be reduced and the structure can be simplified. Furthermore, the slinger 60 can be attached to the inner ring member 3 side instead of the sensor housing 16 side.

  The bearing device of the present invention is not limited to the above-described embodiment, and various modes are possible. For example, FIG. 18 shows still another embodiment of the bearing device of the present invention. Instead of the double-row displacement sensor 24, a single-row displacement sensor 24 is employed as in the first proposal described above. You can also. Moreover, the vehicle outer side end part of the sensor housing 16 can also be sealed with an outer side sealing device.

  FIG. 19 shows still another embodiment of the bearing device of the present invention. In this embodiment, the displacement sensor 24 is a single row, and the vehicle inner side end portion of the bearing device is a vehicle of a rotating raceway. It is closed with a lid member 42 provided with an axial displacement sensor 41 for detecting a gap with the shaft end surface of the inner side end. Further, in the embodiment shown in FIG. 19, the displacement sensor 24 is a single row, and the axial length of the detected portion by the displacement sensor 24 is not so much required, so the sensor target 4 is omitted. The displacement sensor 24 is configured to detect a gap with the outer peripheral surface of the inner ring member 3. In the embodiment shown in FIG. 18 as well, the sensor target 4 can be omitted and the displacement sensor 24 can be configured to detect a gap with the outer peripheral surface of the inner ring member 3.

Next, as in the embodiment shown in FIG. 19, a calculation method of each load in the bearing device including the single row displacement sensor 24 and the axial direction sensor 41 will be described.
The displacement sensor 24 is provided at four locations in the circumferential direction (upper and lower two locations and front and rear two locations), while the axial displacement sensor 41 is provided at two locations in the vertical direction.
In the bearing device in which the sensor is arranged as described above, the load can be obtained by associating the acting load (tire force) with the displacement of the rotating raceway in advance. That is, the direction sensor (Fsx, Fsy, Fsz, Msx, Msz) about the x-axis, y-axis, and z-axis of the load acting on the rotating raceway can be calculated by the displacement sensor.

The front and rear displacement sensors, the upper and lower displacement sensors, and the upper and lower axial displacement sensors are connected to an arithmetic processing unit (not shown). This calculation processing unit can be a control means (ECU) mounted on the vehicle body side, and can calculate the output value of each displacement sensor.
FIG. 20 shows the displacement of the rotating raceway obtained from the output value of each displacement sensor when force / moment is applied to the wheel attached to the rotating raceway. In other words, FIG. 20 shows the loads applied to the wheels in the x-axis direction (Fx input), the y-axis direction load (Fy input), the z-axis direction load (Fz input), and the moment. Rotation obtained from the detected values (gap) of the front and rear displacement sensors, the upper and lower axial displacement sensors, and the upper and lower displacement sensors when the moment (Mx input) and the moment about the z axis (Mz input) are applied. Each displacement of a bearing ring is shown as a graph.

The general formula showing (arranging) FIG. 20 as a determinant is formula (6), and the matrix M of the determinant obtained from the result of FIG. That is, Expressions (6) and (7) express the relationship between the displacement sensors and the load / moment in each direction as a determinant. The inverse matrix M ⁻¹ of this matrix M is obtained by the equation (8). By calculating the equation (9) using the value obtained by each displacement sensor and the inverse matrix M ⁻¹ , the wheel ( The components (Fsx, Fsy, Fsz, Msx, Msz) in the respective axial directions acting on the rotating raceway can be obtained by calculation.

According to each of the displacement sensors and the arithmetic processing unit described above, a wheel (rotating raceway) is obtained by calculating an output value from each displacement sensor and a predetermined function (inverse matrix M ⁻¹ ) stored in advance. It is possible to calculate the components (Fsx, Fsy, Fsz, Msx, Msz) in the respective axial directions of the load acting on the tire (tire force). In addition, since the displacement sensor 24 is symmetrically arranged on the top and bottom and front and back with the center line C interposed therebetween, it is not necessary to perform temperature correction by calculating the difference between the output values.

It is an axial section explanatory drawing of one embodiment of a bearing device of the present invention. It is the elements on larger scale of the bearing apparatus shown by FIG. It is an axial section explanatory view of other embodiments of the bearing device of the present invention. FIG. 4 is a partially enlarged view of the bearing device shown in FIG. 3. It is a fragmentary sectional view of further another embodiment of the bearing device of the present invention. It is a fragmentary sectional view of other embodiment of the bearing device of the present invention. It is a figure showing the positional relationship of the displacement sensor and step part in the bearing apparatus shown by FIG. It is the bearing apparatus shown by FIG. 1, Comprising: It is the figure which looked at the state which removed the inner side sealing apparatus from the vehicle inner side. (A) is a circuit diagram which shows an example of the detection circuit of the gap by a sensor apparatus, (b) is function explanatory drawing of a coil element. It is a figure which shows the arrangement position of each displacement sensor, and the definition of the detected value. (A) is a graph which shows the calculation method of sXy, (b) is a figure which shows the deformation | transformation behavior of the rotation raceway by the load Fy. It is a figure which shows the deformation | transformation state of the rotating raceway in a pure moment state. It is a figure which shows the deformation | transformation state of a rotation bearing ring when a moment load and a translation load act. (A) is a line graph of mz and _{x i} in pure moment state, (b) is a line graph of mx and _{z i} in pure moment state, showing the (c) the calculation of the correction coefficient kz and kx It is a formula. It is a block diagram which shows the calculation method in a control means. It is a matrix figure which shows the correspondence of the independent variable calculated from the sensor output, and the actual load which acts on a wheel. It is a perspective view of a wheel portion showing the definition of each load with x-axis direction, y-axis direction, and z-axis direction. It is an axial direction cross section explanatory drawing of further another embodiment of the bearing apparatus of this invention. It is an axial section explanatory view of other embodiments of the bearing device of the present invention. It is a graph which shows the displacement of the rotation track | orbit calculated | required from the output value of each displacement sensor at the time of applying force and moment to the wheel attached to the rotation track | orbit ring.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Outer ring 2 Inner shaft 3 Inner ring member 4 Sensor target 5 Rolling element 7 Flange
8 inner raceway surface 9 outer raceway surface 14 sensor device 16 sensor housing 21 first sensor member 22 second sensor member 24 displacement sensor 40 wiring board 41 axial displacement sensor 42 lid member 50 pack seal 51 seal metal core 52 seal metal core 53 Seal body 60 Slinger 61 Seal body 62 Lid member

Claims (4)

A cylindrical fixed race ring fixed to the vehicle body side, a rotary race ring rotatably inserted into the fixed race ring, and a double row of rolls arranged between these race rings. A rolling bearing device for a wheel provided with rolling elements,
An annular sensor housing having a plurality of displacement sensors in the circumferential direction for detecting a gap with the outer peripheral surface of the vehicle inner side end of the rotating raceway is attached to the vehicle inner side end of the fixed raceway. A rolling bearing device for a wheel, wherein the displacement sensor is covered with a synthetic resin or a rubber material and integrated with the sensor housing.   2. The wheel rolling bearing device according to claim 1, wherein each of the plurality of displacement sensors includes a first displacement sensor and a second displacement sensor that detect the gaps at positions separated in an axial direction on a peripheral side surface of the rotating raceway.   The rolling bearing device for a wheel according to claim 1, wherein a vehicle inner side end portion of the sensor housing is sealed with an inner side sealing device.   The rolling bearing device for a wheel according to any one of claims 1 to 3, wherein a vehicle outer side end portion of the sensor housing is sealed by an outer side sealing device.

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