JP2008164046A - Sensor-equipped bearing for wheel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sensor-equipped bearing for a wheel, which enables a load sensor to be compactly mounted on the vehicle and to accurately detect a load on the wheel. <P>SOLUTION: The sensor-equipped bearing 10 for the wheel includes: a fixed ring 1 having double row rolling surfaces 4; a rotating ring 2 having rolling surfaces 5 facing the rolling surfaces 4 of the fixed ring 1; and double row rolling bodies 3 interposed between the rolling surfaces 4, 5 facing each other. The bearing 10 supports the wheel in a rotatable manner relative to a vehicle body. The bearing 10 is provided with a displacement sensor 15 comprising a detecting part 17 mounted on the fixed ring 1 and a detected part 16 arranged on the rotating ring 2. The displacement sensor 15 detects a gap between the fixed ring 1 and the rotating ring 2 which varies depending on force acting between a tire and a road surface or a preload of the bearing for the wheel. Further, the bearing 10 is provided with an estimation means 19 for estimating the force acting between the tire and the road surface or the preload of the bearing for the wheel by comparing output signals of the displacement sensor 15 in two kinds of states in which phases in array pitch of the rolling bodies 3 with respect to the detecting part 17 are different from each other. <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.

In response to such demands, wheel bearings have been proposed in which a gap (relative displacement) between a rotation side and a fixed side is measured using a displacement sensor and a load is calculated (for example, Patent Documents 1 and 2). ).
JP 2004-00398 A Japanese Patent Laid-Open No. 2004-232795

However, in the techniques disclosed in Patent Documents 1 and 2, the rigidity in the load direction varies depending on the arrangement state of the rolling elements, and even if the same load is applied, the output signal of the detection unit varies, so the load cannot be detected accurately. There is a problem. As a specific example, as shown in FIG. 7, a vertical load Fz is applied to the bearing, and the detection unit 37 of the displacement sensor is placed on the inner ring surface of the outer ring serving as a fixed ring of the wheel bearing, and the outer ring surface of the inner ring serving as a rotating wheel. A problem in the case of detecting the gap (relative displacement) between the rotating wheel and the fixed wheel by providing the detected portions 36 of the displacement sensor respectively will be described below.
7A shows a rolling element arrangement in the case where the detection unit 37 of the displacement sensor has the same phase as the rolling element 23, and FIG. 7B shows that the detection part 37 of the displacement sensor moves from the rolling element 23 to P / 2 (P Represents the rolling element arrangement in the case where the phase is shifted. Depending on the number of rolling elements 23, the bearing rigidity is different between the case of FIG. 7A and the case of FIG. 7B, and the gap between the fixed ring and the rotating ring is different even when the same load is applied. An accurate load cannot be calculated.

  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, the wheel bearing is composed of a detection unit provided on the fixed wheel and a detected unit disposed on the rotation wheel. In addition, at least one displacement sensor for detecting a gap between the fixed wheel and the rotating wheel, which varies depending on an acting force between the tire and the road surface or a preload amount of the wheel bearing, is provided, and the arrangement of the rolling elements with respect to the detection unit Characterized in that there is provided an estimation means for estimating an acting force between a tire and a road surface or a preload amount of a wheel bearing by comparing output signals of the displacement sensor in two kinds of states having different phases in the pitch. To do.
According to this configuration, the output signal of the displacement sensor in two types of states in which the phases in the arrangement pitch of the rolling elements with respect to the detection unit of the displacement sensor are different from each other is compared by the estimation means. Since the force or the preload amount of the wheel bearing is estimated, 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.

  In this invention, the said estimation means may obtain | require the difference or ratio of the output signal of a change sensor in the said 2 types of state. In the case of this configuration, the difference or ratio between the output signals of the displacement sensor in two types of states in which the phases in the arrangement pitch of the rolling elements with respect to the detection unit of the displacement sensor are different from each other is calculated by the estimation means, Estimate the acting force between the road and the road surface or the preload amount of the wheel bearing.

In the present invention, the estimating means estimates a load acting on the wheel bearing by taking into account the magnitude of the output signal of the displacement sensor in addition to the difference or ratio of the output signal of the displacement sensor. Also good.
In the case of this configuration, even when the difference or ratio value of the output signals of the displacement sensor is small with respect to the change in load, it is possible to detect the load with high sensitivity.

  In the present invention, the two types of states having different phases within the arrangement pitch of the rolling elements with respect to the detection unit are a state in which the rolling element is in the same phase as the detection unit of the displacement sensor, and the rolling element is the displacement sensor. It may be in a state of being in a phase of P / 2 (P: the pitch of the rolling elements) from the detector. In the case of this configuration, the estimation means differs between the output signal of the displacement sensor in the arrangement state of the rolling elements with high bearing rigidity and the output signal of the displacement sensor in the arrangement state of the rolling elements with low bearing rigidity. Since the load is estimated by obtaining the ratio, more accurate load detection is possible.

  In this invention, two rolling element detection means are arranged in at least one of the double-row rolling element rows, and one rolling element detection means is nP (n = 0, 1, 1) with respect to the detection part of the displacement sensor. ..)) And the other rolling element detection means may be arranged so that the phase of the displacement sensor is nP + P / 2 (n = 0, 1,...). good. Also in this configuration, the estimation means makes a difference between the output signal of the displacement sensor in the arrangement state of the rolling elements with high bearing rigidity and the output signal of the displacement sensor in the arrangement state of the rolling elements with low bearing rigidity. Alternatively, since the load is estimated by obtaining the ratio, more accurate load detection is possible.

  In the present invention, the displacement sensor and the rolling element detection means may be arranged in pairs for each of the inboard side rolling element row and the outboard side rolling element row. In the case of this configuration, it is possible to consider the bearing rigidity in the rolling element rows on both the inboard side and the outboard side, so that more accurate load detection is possible.

  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, the wheel bearing is composed of a detection unit provided on the fixed wheel and a detected unit disposed on the rotation wheel. In addition, at least one displacement sensor for detecting a gap between the fixed wheel and the rotating wheel, which varies depending on an acting force between the tire and the road surface or a preload amount of the wheel bearing, is provided, and the arrangement of the rolling elements with respect to the detection unit Since the estimation means for estimating the acting force between the tire and the road surface or the preload amount of the wheel bearing is provided by comparing the output signals of the displacement sensors in two different states in the pitch, the vehicle is compact. Load sensor on Made location, can accurately detect the load applied to the wheels.

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 each of the rolling surfaces 4 and 5 is formed such 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.

  As an example, the wheel bearing 10 is provided with a displacement sensor 15 as a load sensor that detects a gap between the outer member 1 and the inner member 2 that changes due to the acting force between the tire and the road surface. The displacement sensor 15 includes a ring-shaped detected portion 16 provided concentrically with the inner member 2 on the outer periphery of the inner member 2, and an inner side of the outer member 1 so as to face the detected portion 16 in the radial direction. The output signal varies depending on the gap between the detected part 16 and the detection part 17. In this case, the displacement sensor 15 is arranged between the row of rolling elements 3 on the outboard side and the row of rolling elements 3 on the inboard side. In addition, here, the case where the displacement sensor 15 detects the vertical load Fz out of the acting force between the tire and the road surface is illustrated. Therefore, the detection unit 17 of the displacement sensor 15 is positioned as a suitable position for detecting the vertical load Fz as shown in FIG. 1 and FIG. 2 showing a front view seen from the inboard side of FIG. One is provided on each of the upper side surface (upper side with respect to the vehicle) in the vertical direction (Z-axis direction) and the lower side surface (lower side with respect to the vehicle) in the vertical direction. 4A shows a waveform diagram of an example of the output signal of the detection unit 17, and FIG. 4B shows a waveform diagram of another example of the output signal. In addition, sectional drawing of the wheel bearing 10 in FIG. 1 shows the IOOI arrow cross section in FIG.

  Further, as shown in FIG. 1 and FIG. 3, the rolling body 3 on the outboard side is detected at a position adjacent to the outboard side from the position of the rolling body row on the outboard side on the inner peripheral surface of the outer member 1. Two rolling element detection means 18A and 18B are provided. Among them, the first rolling element detection means 18A is provided on the upper side in the vertical direction corresponding to one detection unit 17 of the displacement sensor 15, and P / 2 (P The second rolling element detection means 18B is provided at a position shifted by the rolling element pitch. FIG. 5A shows a waveform diagram of a detection signal of the rolling element 3 by the first rolling element detection means 18A, and FIG. 5B shows a detection signal of the rolling element 3 by the second rolling element detection means 18B. The waveform diagram of is shown. In these waveform diagrams, the peak of each detection signal indicates a point in time when the rolling element 3 passes through the installation position of each rolling element detection means 18A, 18B, and P / 2 is between the peaks of both detection signals. A phase difference occurs. That is, the arrangement state of the rolling elements 3 in the rolling element row at the timing when the first rolling element detection means 18A detects the rolling elements 3, and the timing at which the second rolling element detection means 18B detects the rolling elements 3. A phase difference of P / 2 occurs between the rolling elements 3 in the arrangement state of the rolling elements 3 in FIG. Since the bearing rigidity differs depending on the arrangement state of these two rolling elements 3, the two rolling element detection means 18A, 18B play a role of detecting the timing when the above-described two rolling element arrangement states having different bearing rigidity are obtained.

The detection unit 17 of the displacement sensor 15 and the rolling element detection means 18A and 18B are connected to an estimation means 19 as shown in FIG. The estimation means 19 is a means for estimating the acting force between the tire and the road surface (here, the vertical load Fz) from the output signal of the detection unit 17 of the displacement sensor 15. The estimation means 19 has a relation setting means (not shown) such as a table or an arithmetic expression in which the relation between the output signal of the displacement sensor 15 and the acting force between the tire and the road surface is set, and the output signal is used as the relation setting means. The action force is estimated by comparing with the setting contents of. The contents of the relationship setting means are set based on values measured in advance, simulation results, and the like before use by a user of a vehicle equipped with a wheel bearing with sensor.
Specifically, the estimating means 19 is the timing at which the first rolling element detection means 18A detects the rolling element 3 (at the peak of the signal waveform in FIG. 5A: the arrangement of the rolling elements 3 with increased bearing rigidity). Output value of the displacement sensor detector 17 in the state) (for example, the peak value V1 in the waveform of FIG. 4A or the peak value V3 in the waveform of FIG. 4B) and the second rolling element The output value (for example, FIG. 4 (FIG. 4)) at the timing when the detecting means 18B detects the rolling element 3 (at the peak of the signal waveform in FIG. 5B: the arrangement state of the rolling elements 3 at which the bearing rigidity decreases). 4), or the difference (V1−V2), (V1−V2) between the output values V1, V2 (V3, V4). V3-V4) or ratio (V1 / V2), (V3 / V ) From estimating the vertical load Fz. That is, the estimation means 19 takes in the detection values of the displacement sensor detection unit 17 in two types of states in which the phases within the arrangement pitch of the rolling elements 3 in the rolling body row on the outboard side with respect to the displacement sensor detection unit 17 are different from each other, The vertical load Fz is estimated from the difference or ratio of these output values.

As the displacement sensor 15, for example, a sensor utilizing light, eddy current, or the like can be used. Moreover, in this embodiment, although the ring-shaped member is provided in the outer periphery of the inner member 2 as the to-be-detected part 16 of the displacement sensor 15, the outer diameter of the inner member 2 is provided without providing a ring-shaped member. The surface may be the detected portion 16. The rolling element detection means 18A and 18B may be any means capable of determining the presence or absence of the rolling element 3, and for example, a proximity switch using light or the like can be used.
In addition, the installation position and the number of the detection unit 17 and the rolling element detection units 18A and 18B of the displacement sensor 15 are not particularly limited. For example, in this embodiment, the bearing rigidity is determined at a timing when the rolling element 3 passes the detection unit 17 of the displacement sensor 15 and a timing at which an intermediate position between the adjacent rolling elements 3 and 3 passes the detection unit 17 of the displacement sensor 15. Therefore, the rolling element detection means 18A and 18B are installed at the above-described positions. However, if the bearing rigidity changes greatly at other locations, the rolling elements 3 pass through the locations. The rolling element detection means 18A and 18B may be arranged so that the timing can be detected.

  As described above, in the sensor-equipped wheel bearing 10, the detecting portion 17 of the displacement sensor 15 is provided on the outer member 1 serving as a fixed ring, and the detected portion 16 of the displacement sensor 15 is provided on the inner member 2 serving as a rotating wheel. The displacement sensor 15 detects a gap between the inner and outer members 2 and 1 that is arranged and changes due to an acting force between the tire and the road surface (for example, vertical load Fz), and within the arrangement pitch of the rolling elements 3 with respect to the detection unit 17. Since the difference or ratio between the output signals of the displacement sensor 15 in two different states is calculated by the estimating means 19 and the vertical load Fz is estimated from this calculated value, for example, Such a load can be accurately detected, and the detection result can be used for vehicle control of an 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.

  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.

  In this embodiment, the first rolling element detection means 18A is arranged at an upper position corresponding to the position of the detection unit 17 of the displacement sensor 15, and the second rolling element detection means 1B is arranged in the detection unit 17. Although it arrange | positions in the position shifted P / 2 from the position, the installation position is not restricted to this. That is, the first rolling element detection means 18A is displaced by nP (n = 0, 1,...) With respect to the position of the detection unit 17 of the displacement sensor 15, and the second rolling element detection means 18B is displaced. 5 may be set to nP + P / 2 (n = 0, 1,...) With respect to the position of the detection unit 17 of the sensor 15, and when arranged at the position of this condition, the rolling element detection means 18A and 18B are used as shown in FIG. An output signal similar to B) is obtained.

Further, in this embodiment, in the load estimation by the estimating means 19, as described above, the maximum value of the detection value of the displacement sensor detection unit 17 (V1 in the case of FIG. 4A, V3 in the case of FIG. 4B). And the difference (V1-2), (V3-V4) or the ratio (V1 / V2), (V3 / V4) between the minimum value (V3 in FIG. 4A and V4 in FIG. 4B) However, if the value of such a difference or ratio is small with respect to the change in load, the load may be estimated by adding the magnitude of the output signal to these values as follows. . That is, for example, in the case of the output signal in FIG. 4A, the difference between the maximum value and the minimum value is multiplied by the maximum value (V1−V2) × V1, or the ratio between the maximum value and the minimum value is multiplied by the maximum value. The obtained value (V1 / V2) × V1. In the case of the output signal of FIG. 4B, it is set to (V3−V4) × V3 or (V3 / V4) × V3.
For example, in the case of the vertical load Fz, as the load increases, the gap between the inner and outer members 2 and 1 becomes narrower and the output signal of the displacement sensor 15 becomes larger. If the load is calculated in consideration of the above, the detection sensitivity can be increased.

  In the above embodiment, for example, without providing the rolling element detection means 18A and 18B, the maximum value and the minimum value of the output signal of the displacement sensor 15 may be obtained, and the difference or ratio may be calculated to calculate the load. it can. Further, the number of the rolling elements 3 or the shapes of the inner and outer members 2 and 1 may be devised so that the bearing rigidity changes depending on the arrangement state of the rolling elements 3 as long as the bearing performance is not affected. .

  FIG. 6 shows another embodiment of the present invention. In the sensor-equipped wheel bearing 10, in the previous embodiment, one set of the displacement sensor 15 and the rolling element detection means 18A and 18B are provided for each of the inboard side rolling element row and the outboard side rolling element row. Provided. That is, a set of displacement sensor 15 and rolling element detection means 18A, 18B are arranged at a position offset from the rolling body row on the inboard side toward the inboard side, and offset from the rolling body row on the outboard side toward the outboard side. Another set of displacement sensor 15 and rolling element detection means 18A, 18B are arranged at the position. The estimation means 19 estimates the load from the output signal of each set of displacement sensors 15. Other configurations are the same as those in the previous embodiment.

  In this embodiment, since the bearing rigidity in the rolling element rows on both the inboard side and the outboard side can be considered, the load can be calculated more accurately.

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 by the side of the outboard in the wheel bearing. (A) is a waveform diagram of an example of an output signal of a displacement sensor in the bearing for the wheel, and (B) is a waveform diagram of another example of the output signal. (A) is the output waveform figure of the 1st rolling element detection means in the bearing for the wheels, (B) is the output waveform figure of the 2nd rolling element detection means. It is a block diagram of the sensor-equipped wheel bearing which concerns on other embodiment of this invention. It is explanatory drawing of the subject in a prior art example.

Explanation of symbols

1. Outer member (fixed ring)
2 ... Inward member (rotating wheel)
3 ... rolling elements 4, 5 ... rolling surface 15 ... displacement sensor 16 ... detected part 17 ... detecting parts 18A, 18B ... rolling element detecting means 19 ... estimating means

Claims (6)

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,
The gap between the fixed wheel and the rotating wheel, which is composed of a detecting part provided on the fixed wheel and a detected part arranged on the rotating wheel, varies depending on the acting force between the tire and the road surface or the preload amount of the wheel bearing. By providing at least one displacement sensor to detect and comparing the output signals of the displacement sensor in two different states with different phases within the arrangement pitch of the rolling elements with respect to the detection unit, A wheel bearing with a sensor, characterized in that an estimation means for estimating an acting force or a preload amount of the wheel bearing is provided.   2. The sensor-equipped wheel bearing according to claim 1, wherein the estimating means obtains a difference or ratio of output signals of the displacement sensor in the two kinds of states.   In Claim 2, the said estimation means estimates the load which acts on the wheel bearing considering the magnitude | size of the output signal of a displacement sensor in addition to the difference or ratio of the output signal of the said displacement sensor. Wheel bearing with sensor.   In Claims 1 and 3, the two types of states in which the phases within the arrangement pitch of the rolling elements with respect to the detection unit are different from each other are a state in which the rolling element is in the same phase as the detection unit of the displacement sensor. A wheel bearing with sensor, wherein the moving body is in a phase of P / 2 (P: the pitch of the rolling body) from the detection unit of the displacement sensor.   5. The rolling element detection means according to claim 1, wherein at least one of the rolling element rows in the double row is arranged with at least two rolling element detection means, and the one rolling element detection means is provided in the detection unit of the displacement sensor. The other rolling element detection means is arranged to be nP + P / 2 (n = 0, 1,...) With respect to the detection part of the displacement sensor. The wheel bearing with sensor is arranged so that the phase becomes. 6. The sensor-equipped wheel bearing according to claim 5, wherein one set of the displacement sensor and the rolling element detection means is arranged for each of the inboard side rolling element array and the outboard side rolling element array.

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