JP2008164448A - Wheel bearing with sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wheel bearing with a sensor that can compactly install a load sensor to a vehicle and accurately detect a load applied to a wheel. <P>SOLUTION: The wheel bearing 10 with the sensor includes a fixed ring 1 having a plurality of rows of rolling surfaces 4, a rotation ring 2 having a rolling surface 5 facing the rolling surface 4 of the fixed ring 1, and a plurality of rows of rolling elements 3 interposed between both facing rolling surfaces 4 and 5, and rotatably supports the wheel with respect to the vehicle body. At least one set of ultrasonic sensors 15A and 15B, two of which form one set, is disposed near the axial position having the rolling surface 4 of the fixed ring 1. The two ultrasonic sensors 15A and 15B are arranged on a plane perpendicular to the axial center of the wheel bearing 10, mutually separately by phase of nP (n: arbitrary natural number, P: rolling element pitch), symmetrically to the center axis for connecting the intersection point of the maximum load point of the rolling element to the load direction to be detected and the axial center of the wheel bearing. The wheel bearing has an estimating means 16 for estimating the action force between a tire and the road surface or the preload amount of the wheel bearing based on the echo of the two ultrasonic sensors. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

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

2. Description of the Related Art Conventionally, there is a wheel bearing provided with a sensor for detecting the rotational speed of each wheel for safe driving of an automobile. Conventional measures to ensure driving safety of general automobiles are performed by detecting the rotational speed of the wheels of each part, but the rotational speed of the wheels is not sufficient, and it is further safer by using other sensor signals. It is required that the surface can be controlled.
Therefore, it is conceivable to control the posture from the load acting on each wheel during vehicle travel. For example, a large load is applied to the outer wheel in cornering, and the load applied to each wheel is not uniform. In addition, even when the load is uneven, the load applied to each wheel is uneven. For this reason, if the load applied to the wheel can be detected at any time, the suspension control etc. is controlled in advance based on the detection result, thereby controlling the attitude during vehicle travel (preventing rolling during cornering, preventing the front wheel from sinking during braking, It is possible to prevent subsidence due to uneven load capacity. However, there is no appropriate installation location of a sensor that detects a load acting on the wheel, and it is difficult to realize posture control by load detection.
In addition, when steer-by-wire is introduced in the future and the system becomes a system in which the axle and the steering are not mechanically coupled, it is required to detect the axle direction load and transmit the road surface information to the handle held by the driver.

As a response to such a demand, a wheel bearing has been proposed in which an ultrasonic sensor is provided on the outer ring of the wheel bearing and the load is detected from an echo ratio that varies depending on the contact area between the rolling element and the rolling surface (for example, Patent Document 1).
JP 2006-177932 A

  However, with the technique disclosed in Patent Document 1, when the applied load increases, the contact area between the rolling element and the rolling surface increases, but since the amount of change is small, there is a problem that it is difficult to accurately detect the load. is there.

  An object of the present invention is to provide a sensor-equipped wheel bearing in which a load sensor can be compactly installed in a vehicle and a load applied to the wheel can be accurately detected.

The sensor-equipped wheel bearing according to the present invention includes a fixed wheel having a double-row rolling surface, a rotating wheel having a rolling surface facing the rolling surface of the fixed wheel, and both facing rolling surfaces. In a wheel bearing having a double row rolling element interposed therebetween and rotatably supporting the wheel with respect to the vehicle body, two in the vicinity of the axial position where the rolling surface of the fixed wheel is provided At least one set of ultrasonic sensors is provided, and the two ultrasonic sensors are arranged in a plane perpendicular to the axis of the wheel bearing and the maximum load point of the rolling element with respect to the load direction to be detected and the wheel The tire is arranged symmetrically with respect to the central axis connecting the intersection with the shaft center of the bearing and separated by a phase of nP (n: arbitrary natural number, P: rolling element pitch), and from the echoes of the two ultrasonic sensors. To estimate the acting force between the vehicle and the road surface or the preload amount of the wheel bearing Characterized in that a stage.
For example, when detecting a load applied in the vertical direction (upward), the central axis is the central axis in the vertical direction with respect to the ground contact surface between the tire and the road surface in the plane. Two sets of ultrasonic sensors are arranged symmetrically with respect to the central axis and separated by a phase of nP, and the estimation means reciprocates the reciprocal echoes (1 / reflective echoes) that are output signals of the two ultrasonic sensors. ) To obtain a waveform as a calculation signal. These calculation signals have a peak value in a state where rolling elements are present at the installation position of the ultrasonic sensor. On the other hand, for example, when the rotating wheel is rotating clockwise, the two rolling elements arranged symmetrically with respect to the central axis of the vertical load move in the direction in which the interval increases. Of these, the right ultrasonic sensor detects the rolling element first, and the left ultrasonic sensor detects the rolling element after a delay. Therefore, the estimation means calculates the phase of the rolling element by comparing the n-th peak position in the calculation signal of the right ultrasonic sensor with the n + 1-th peak position in the calculation signal of the left ultrasonic sensor. be able to. Since the phase calculated in this way increases as the load increases, the estimation means can accurately detect the load to be detected from the calculated phase, and the detection result can be used for vehicle control of the automobile. it can. In addition, since the configuration of the load detection sensor is simple, it is possible to install the load sensor in a compact manner in the vehicle, and to improve the mass productivity, thereby reducing the cost.

  In this invention, it is good also as n = 1. In the case of this configuration, the load can be estimated using the rolling element that receives the most load.

  In this invention, you may provide the phase calculation part which calculates the phase of an adjacent rolling element from the echo of the said two ultrasonic sensors.

  In the present invention, the estimating means adds the echoes of the two ultrasonic sensors, converts them into a digital signal using an arbitrary threshold value, calculates the duty ratio, and calculates the duty force or preload from the duty ratio. It is good also as what estimates quantity.

In this invention, symmetrically with respect to the central axis in the vertical direction, at least two ultrasonic sensors with a phase of nP (n: natural number, P: rolling element pitch) are arranged on the upper and lower surfaces of the outer ring. The propulsion means may estimate a vertical load between the tire and the road surface.
When a vertical load is applied between the tire and the road surface, parts such as the outer ring are hardly deformed and the load is easily received by the rolling elements. Therefore, symmetrically with respect to the central axis in the vertical direction, the vertical load can be accurately estimated if at least one pair of ultrasonic sensors is arranged on the upper surface of the outer ring at nP phases. Can do.

  The sensor-equipped wheel bearing according to the present invention includes a fixed wheel having a double-row rolling surface, a rotating wheel having a rolling surface facing the rolling surface of the fixed wheel, and both facing rolling surfaces. In a wheel bearing having a double row rolling element interposed therebetween and rotatably supporting the wheel with respect to the vehicle body, two in the vicinity of the axial position where the rolling surface of the fixed wheel is provided At least one set of ultrasonic sensors is provided, and the two ultrasonic sensors are arranged in a plane perpendicular to the axis of the wheel bearing and the maximum load point of the rolling element with respect to the load direction to be detected and the wheel The tire is arranged symmetrically with respect to the central axis connecting the intersection with the shaft center of the bearing and separated by a phase of np (n: arbitrary natural number, p: rolling element pitch), from the echoes of the two ultrasonic sensors. To estimate the acting force between the vehicle and the road surface or the preload amount of the wheel bearing Because having a stage, made compact installed load sensors in the vehicle can accurately detect the load applied to the wheel.

An embodiment of the present invention will be described with reference to FIGS. This embodiment is a third generation inner ring rotating type and is applied to a wheel bearing for driving wheel support. In this specification, the side closer to the outer side in the vehicle width direction of the vehicle when attached to the vehicle is referred to as the outboard side, and the side closer to the center of the vehicle is referred to as the inboard side. In FIG. 1, the left side is the outboard side and the right side is the inboard side.
As shown in FIG. 1, the wheel bearing 10 is formed with an outer member 1 in which double-row rolling surfaces 4 are formed on the inner periphery, and rolling surfaces 5 respectively facing the rolling surfaces 4. The inner member 2 and the double row rolling elements 3 interposed between the double row rolling surfaces 4 and 5 are provided. The wheel bearing 10 is a double-row angular ball bearing type, and the rolling elements 3 are formed of balls and are held by a cage 6 for each row. Each of the rolling surfaces 4 and 5 has an arc shape in cross section, and is formed so that the ball contact angle is aligned with the back surface. The open end portions on the outboard side and the inboard side of the annular space formed between the inner and outer members 2 and 1 are sealed by contact-type seals 7 and 8 which are sealing devices, respectively.

The outer member 1 is a fixed wheel, and a flange 1a formed on the outer periphery thereof is fastened to a knuckle (not shown) on the vehicle body side with a bolt.
The inner member 2 is a rotating wheel, and includes a hub wheel 2A having a wheel mounting flange 2a on the outer periphery, and a separate inner ring 2B fitted to the outer periphery on the inboard side of the hub wheel 2A. An outer ring 11a, which is one joint member of the constant velocity joint 11, is connected to the hub wheel 2A. Each row of rolling surfaces 5 is formed on the hub wheel 2A and the inner ring 2B. The hub wheel 2 </ b> A has a center hole 12, and a stem 13 integrally formed with the constant velocity joint outer ring 11 a is inserted into the center hole 12. The joint outer ring 11 a is connected to the inner member 2. At this time, the step surface 11aa facing the outboard provided on the constant velocity joint outer ring 11a is pressed against the end surface facing the inboard side of the inner ring 2B press-fitted into the hub wheel 2A, and the constant velocity joint outer ring 11a and the nut 14 Thus, the inner member 2 is tightened. A spline groove 12a is formed in the center hole 12 of the hub wheel 2A and is fitted to the spline groove 13a of the stem 13 by spline fitting.

  The wheel bearing 10 is provided with at least one set of two ultrasonic sensors 15A and 15B as a load sensor. In this case, each set of ultrasonic sensors 15A and 15B detects the acting force between the tire and the road surface or the preload amount of the wheel bearing 10 in terms of the magnitude of the echo of the transmitted wave or the reflected wave. In this embodiment, it is used to detect the vertical load Fz out of the acting force between the tire and the road surface. Specifically, as shown in FIG. 1 and FIG. 2 showing a front view as seen from the inboard side of FIG. Two sets of ultrasonic sensors 15A and 15B are provided in the vicinity of each axial position (position of each rolling element row) on which the surface 4 is provided. In addition, sectional drawing of the wheel bearing 10 in FIG. 1 shows the IOO arrow sectional drawing in FIG.

Each of the two ultrasonic sensors 15A and 15B in one set has a load direction as a detection target in a plane perpendicular to the axis of the wheel bearing 10 as shown in FIG. 3 showing a cross-sectional view of each rolling element row. (Here, vertical load Fz) symmetrical with respect to the central axis Z connecting the intersection of the maximum load point of the rolling elements and the axis of the wheel bearing, and nP (n: any natural number, P: rolling element) (Pitch) phase. Here, on the upper surface portion (upper side with respect to the vehicle) of the outer peripheral surface of the fixed wheel 1, a pair of two ultrasonic sensors 15A and 15B are symmetrical with respect to the central axis Z and the phase of the rolling element pitch P (When n = 1), the two ultrasonic sensors 15A and 15B, which are another set, are arranged at the center on the lower surface portion (lower side with respect to the vehicle) on the outer peripheral surface of the fixed wheel 1 as well. They are arranged symmetrically with respect to the axis Z and separated by the phase of the rolling element pitch P. That is, one set of ultrasonic sensors 15A and 15B disposed on the upper surface portion of the fixed ring 1 is used to detect the upward vertical load Fz, and another set of supersonic sensors disposed on the lower surface portion of the fixed ring 1. The acoustic wave sensors 15A and 15B are used for detecting the downward vertical load Fz.
In this case, the ultrasonic sensors 15A and 15B are installed toward the contact portion between the rolling element 3 and the rolling surface 4, and the position of the rolling element 3 and the contact area between the rolling element 3 and the rolling surface 4 as described later. The magnitude of the echo of the transmitted wave or reflected wave that changes according to the frequency is detected.

  Here, as described above, the two ultrasonic sensors 15A and 15B forming a pair are arranged in the same phase as the rolling element pitch P. However, when the number of the rolling elements 3 is large, nP (n = Two ultrasonic sensors 15A, 15B may be arranged at intervals of 1, 2, 3,. In this embodiment where n = 1, the load can be estimated using the rolling element 3 receiving the most load. The number of sets of ultrasonic sensors 15A and 15B that form one set of two is not particularly limited because the required number of sets differs depending on the number of load detection directions.

  The ultrasonic sensors 15A and 15B are connected to the estimation means 16 as shown in FIG. The estimation means 16 is means for estimating the acting force between the tire and the road surface or the preload amount of the wheel bearing 10 from the echoes detected by the two ultrasonic sensors 15A and 15B. In this embodiment, the vertical direction described above is used. The load Fz is estimated. The estimation unit 16 includes a phase calculation unit 17 that calculates the phase of the adjacent rolling elements 3 from echoes detected by the two ultrasonic sensors 15A and 15B. The estimation unit 16 includes a relationship setting unit (not shown) in which the relationship between the echoes detected by the two ultrasonic sensors 15A and 15B and the vertical load Fz or the preload amount is set as a table or an arithmetic expression. The echoes detected by the ultrasonic sensors 15A and 15B are compared with the relationship data set in the relationship setting means, and the vertical load Fz or the preload amount is output. The relational data is obtained and set in advance by, for example, a test or a simulation before use by a vehicle user using the sensor-equipped wheel bearing. In the case where the phase calculation unit 17 is provided, the relationship data includes a relationship between the detection echo, a phase detected by the phase calculation unit 17, and the vertical load Fz or the preload amount.

  Next, an example of load detection processing in the sensor-equipped wheel bearing 10 will be described. FIG. 4 shows the waveform of the calculation signal obtained by calculating the output signals of the upper two ultrasonic sensors 15A and 15B when the load Fz is applied in the vertical direction (upward) in each rolling element row as shown in FIG. An example of the figure is shown. Specifically, the calculation signal in this case is a waveform obtained by obtaining the reciprocal of the reflected echo (1 / reflected echo) that is the output signal of the ultrasonic sensors 15A and 15B. In the wheel bearing 10, since the ultrasonic wave is transmitted to the rotating wheel 2 side as the contact area between the rolling element 3 and the rolling surface 4 is larger, the size of the reflected echo detected by the ultrasonic sensors 15A and 15B becomes smaller. Therefore, the calculation signal obtained as the reciprocal of the reflected echo has a peak value in a state where the rolling elements 3 exist at the positions of the ultrasonic sensors 15 and 15B.

4A shows a waveform diagram of the calculation signal of the first ultrasonic sensor 15A in FIG. 3, and FIG. 4B shows a waveform diagram of the calculation signal of the second ultrasonic sensor 15B in FIG. Show.
When the rotating wheel 2 is rotating clockwise as shown in FIG. 3, the uppermost portion is in the state of FIG. 7A in which the arrangement of the rolling elements 3 overlaps the central axis Z of the vertical load Fz acting on the upper side. The rolling element 3 of does not move. On the other hand, as shown in FIG. 7B, in the state where the two adjacent upper rolling elements 3 and 3 that receive the vertical load Fz are arranged symmetrically with respect to the central axis Z of the vertical load Fz. The two rolling elements 3 and 3 slide along the rolling surfaces 4 and 5 depending on the rolling element pitch P and the lubrication conditions, and move in a direction in which the interval increases as indicated by arrows.
For this reason, the first ultrasonic sensor 15A detects the rolling element 3 first, and the second ultrasonic sensor 15B detects the rolling element 3 with a delay. Therefore, the nth peak position in the calculation signal of the first ultrasonic sensor 15A shown in FIG. 4A and the (n + 1) th calculation signal in the calculation signal of the second ultrasonic sensor 15B shown in FIG. If the peak position is compared, the phase of the rolling element 3 can be calculated. This calculation is performed by the phase calculation unit 17 in the estimation means 16.

If the two ultrasonic sensors 15A and 15B are installed in a state where they are separated by the phase nP of the rolling element 3, the method for calculating the phase nP of the rolling element 3 is, for example, the calculation of the first ultrasonic sensor 15A. The time T [s] between the n-th peak position of the signal and the n + 1-th peak position of the calculation signal of the second ultrasonic sensor 15B (the time here considers the contact area in FIG. 4) And the revolution speed V [rps] of the rolling element 3 is obtained from the period in which the peak of the calculation signal of one of the ultrasonic sensors 15A (15B) occurs, and nP = 360 × V × T It may be calculated as [deg].
The phase calculated in this way increases as the load increases. Therefore, the estimation means 16 estimates the load to be detected (vertical load Fz in this embodiment) from the calculated phase.

  Further, the arithmetic signal in FIG. 4 is converted into a digital signal with an arbitrary threshold value as indicated by a chain line in the same figure, and the nth of the arithmetic signal (FIG. 4A) of the first ultrasonic sensor 15A is converted. The rising position and the (n + 1) th falling position of the calculation signal (FIG. 4B) of the second ultrasonic sensor 15B are obtained, and these are the nth peak of the calculation signal of the first ultrasonic sensor 15A. The phase of the rolling element 3 may be similarly calculated by using the position and the n + 1-th peak position of the calculation signal of the second ultrasonic sensor 15B. Although not a digital signal, this corresponds to the time T1 when the contact area of FIG. 4 is considered. The calculation result is not only the position of the rolling element 3 but also the phase of the rolling element 3 in consideration of the contact area between the rolling element 3 and the rolling surface 4, but when the load increases, the rolling element 3 and the rolling surface 4 Since the contact area also increases, the sensitivity further increases.

Next, another example of load detection processing by the estimating means 16 in the sensor-equipped wheel bearing 10 will be described with reference to FIGS. FIG. 5 is an explanatory diagram of the load detection process when a large load is applied, and FIG. 6 is an explanatory diagram of the load detection process when a small load is applied.
In FIG. 5, first, calculation signals are obtained from the output signals of the two ultrasonic sensors 15A and 15B (FIGS. 5A and 5B), and a calculation signal is created by adding these two calculation signals ( FIG. 5C). Next, the arithmetic signal in FIG. 5C is converted into a digital signal having a waveform as in FIG. 5D using an arbitrary threshold value. Since the duty ratio (X1 / (X1 + X2)) of the digital signal increases as the load increases, the estimation means 16 can estimate the load from the duty ratio.

  In the case of FIG. 6 where the load is small (almost no load is applied), the rolling element 3 exists in the calculation signals (FIGS. 6A and 6B) obtained from the output signals of the ultrasonic sensors 15A and 15B. However, since the load is small, the contact area between the rolling element 3 and the rolling surface 4 is smaller than in the case of FIG. 5, and the amplitude and spread of the waveform are also reduced. In this case, an arithmetic signal obtained by adding two arithmetic signals (FIGS. 6A and 6B) is shown in FIG. 6C. This arithmetic signal is a digital signal with the same threshold as in FIG. FIG. 6D shows the waveform converted into FIG. 6D, and it can be seen that the duty ratio (X1 / (X1 + X2)) is smaller in FIG. 6D than in FIG. 5D.

  Each of the load detection processes described above is an example in which the designation means 16 estimates the upward vertical direct load Fz using the output signals of the ultrasonic sensors 15A and 15B disposed on the upper surface of the fixed ring 1. However, when the output signals of the ultrasonic sensors 15A and 15B arranged on the lower surface portion of the fixed ring 1 are used, the downward vertical load Fz can be estimated in the same manner. Further, the output signals of one set of ultrasonic sensors 15A and 15B arranged on the upper surface of the fixed ring 1, and the output signals of another set of ultrasonic sensors 15A and 15B arranged on the lower surface of the fixed ring 1 and May be compared to estimate the load.

  In each of the load detection processes described above, the reciprocal of the reflected echo (1 / reflected echo) detected by the ultrasonic sensors 15A and 15B is used as a calculation signal. However, by using the output signals of the ultrasonic sensors 15A and 15B as they are. The load may be estimated by the estimating means 16. Furthermore, the load may be estimated by using a reflection echo ratio (a ratio of a reflection echo at a position where the rolling element 3 does not exist to a reflection echo at a position where the rolling element 3 exists).

  Thus, in this sensor-equipped wheel bearing 10, at least one pair of ultrasonic sensors 15 </ b> A and 15 </ b> B is provided in the vicinity of the axial position where the rolling surface 4 of the fixed wheel 1 is provided, The two ultrasonic sensors 15 </ b> A and 15 </ b> B indicate the intersection of the maximum load point of the rolling element with respect to the load direction to be detected and the axis of the wheel bearing in a plane perpendicular to the axis of the wheel bearing 10. The two ultrasonic sensors 15 </ b> A and 15 </ b> B are detected by the estimation means 16 by being arranged symmetrically with respect to the connecting center axis Z and separated by a phase of nP (n: arbitrary natural number, P: rolling element pitch). Since the acting force between the tire and the road surface is estimated from the echo, the load applied to the wheel can be accurately detected, and the detection result can be used for vehicle control of the automobile. In addition, since the configuration of the load detection sensor is simple, it is possible to install the load sensor in a compact manner in the vehicle, and to improve the mass productivity, thereby reducing the cost.

  Further, when a vertical load is applied between the tire and the road surface, parts such as the outer member (fixed wheel) 1 are hardly deformed, and the load is easily received by the rolling elements 3. Therefore, as in this embodiment, symmetrically with respect to the central axis Z in the vertical direction, the upper surface and the lower surface of the fixed ring 1 are at least one pair of the ultrasonic sensors 15A, 15B at a phase of nP. The vertical load Fz can be estimated accurately.

  Moreover, although this embodiment demonstrated the case where the acting force between a tire and a road surface was detected with the said sensor structure, it is applicable similarly when detecting the preload amount of a wheel bearing.

It is a lineblock diagram of the wheel bearing with a sensor concerning one embodiment of this invention. It is the front view which looked at the bearing for the wheels from the inboard side. It is sectional drawing of the rolling element row | line | column in the wheel bearing. It is explanatory drawing of an example of the load estimation process by the estimation means in the wheel bearing. It is explanatory drawing when the big load of the other example of the load estimation process by the estimation means in the same wheel bearing is applied. It is explanatory drawing when the small load of the load estimation process by the estimation means in the wheel bearing is applied. It is explanatory drawing of a movement of the rolling element by the arrangement state of the rolling element in the rolling element row | line | column in the wheel bearing.

Explanation of symbols

1. Outer member (fixed ring)
2 ... Inward member (rotating wheel)
DESCRIPTION OF SYMBOLS 3 ... Rolling element 4, 5 ... Rolling surface 10 ... Wheel bearing 15A, 15B with a sensor ... Ultrasonic sensor 16 ... Estimation means 17 ... Phase calculation part

Claims (5)

A fixed wheel having a double-row rolling surface, a rotating wheel having a rolling surface facing the rolling surface of the fixed wheel, and a double-row rolling element interposed between the opposing rolling surfaces; In a wheel bearing that rotatably supports the wheel with respect to the vehicle body,
At least one set of two ultrasonic sensors is provided near the axial position of the fixed wheel where the rolling surface is provided, and the two ultrasonic sensors are perpendicular to the axis of the wheel bearing. In a plane, symmetrical with respect to the central axis connecting the intersection of the maximum load point of the rolling element with respect to the load direction to be detected and the axis of the wheel bearing, and nP (n: any natural number, P: rolling A sensor-equipped wheel provided with an estimation means that is arranged to be separated by a phase of a moving body pitch) and estimates an acting force between a tire and a road surface or a preload amount of a wheel bearing from echoes of the two ultrasonic sensors. Bearings.   2. The wheel bearing with sensor according to claim 1, wherein n = 1.   The sensor-equipped wheel bearing according to claim 1 or 2, wherein a phase calculation unit that calculates a phase of an adjacent rolling element from echoes of the two ultrasonic sensors is provided.   In Claim 1 or Claim 2, the said estimation means adds up the echo of said two ultrasonic sensors, converts it into a digital signal using arbitrary threshold values, calculates its duty ratio, and calculates from the duty ratio. A wheel bearing with sensor for estimating the acting force or the preload amount. 5. The ultrasonic sensor according to claim 1, wherein at least two ultrasonic sensors are arranged in a phase of nP (n: natural number, P: rolling element pitch) symmetrically with respect to the central axis in the vertical direction. A sensor-equipped wheel bearing in which pairs are arranged on the upper and lower surfaces of the outer ring, and the propulsion means estimates the vertical load between the tire and the road surface.

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