JP2008174067A - Wheel bearing with sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wheel bearing with a sensor capable of compactly installing a load sensor to a vehicle, and precisely detecting a load on a wheel. <P>SOLUTION: The wheel bearing 10 with the sensor comprises a fixed wheel 1 having double-row rolling surfaces 4, a rolling wheel 2 having rolling surfaces 5 opposite to the rolling surfaces 4 of the fixed wheel 1, and double-row rolling elements 3 interposed between both the rolling surfaces 4, 5 opposite to each other. Wheels are rotatably supported to a vehicle body. At a peripheral surface on the bearing space side of the fixed wheel 1, a bypass member 15 having a magnetic flux generating portion generating magnetic flux and a magnetic flux detecting portion detecting the magnetic flux to at least one rolling element row is installed. Therefore, at least one magnetic circuit composed of a part of the fixed wheel 1, at least one rolling element 3, the bypass member 15, and an air gap is provided. An estimating means is provided which estimates an acting force between a tire and a road surface or the pre-load amount of the wheel bearing according to changes of magnetic resistance in the magnetic circuit obtained from a detection output of the magnetic flux detecting portion. <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 and a 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

  In the case of 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 the amount of change is small. Further, in the case of ultrasonic waves, even if it is transmitted from the outer ring to the inner ring side through the rolling element, it may be repeatedly reflected and returned, and is easily affected by ultrasonic waves emitted from other positions. Therefore, there is a problem that it is difficult to accurately detect the load.

  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 wheel bearing according to the present invention includes a fixed ring formed with a double row rolling surface, a rotating wheel formed with a rolling surface facing the rolling surface of the fixed wheel, and both facing rolling surfaces. In a wheel bearing that includes a plurality of intervening rolling elements and rotatably supports the wheel with respect to the vehicle body, a magnetic flux generating section that generates magnetic flux for at least one of the rolling element arrays, and a magnetic flux A bypass member having a magnetic flux detection portion for detecting the fixed ring is installed on a peripheral surface portion of the fixed ring on the bearing space side, and a part of the fixed ring, at least one rolling element, the bypass member, and an air gap At least one magnetic circuit comprising the above is provided, and the acting force between the tire and the road surface or the preload amount of the wheel bearing is estimated from the change in the magnetic resistance in the magnetic circuit obtained from the detection output of the magnetic flux detection unit. It is characterized by providing an estimation means.
In the magnetic circuit in this configuration, when a load is applied to the wheel bearing and a force applied to the rolling element that is a part of the magnetic circuit is increased, a contact area between the rolling element and the rolling surface is increased. Becomes smaller. On the contrary, when the force applied to the rolling element that is a part of the magnetic circuit is reduced, the contact area between the rolling element and the rolling surface is reduced, and thus the magnetic resistance is increased. Therefore, the estimation means can estimate the acting force between the tire and the road surface or the preload amount of the wheel bearing from the change in the magnetic resistance of the magnetic circuit. In this case, since the length of the magnetic circuit is short, it is difficult to be influenced by other magnetic circuits, and the load can be estimated accurately. This 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.

  In this invention, the said bypass member is made into the shape extended over two rolling elements adjacent in the circumferential direction, The said rolling ring, the said rotating wheel, one rolling element of two adjacent rolling elements, the said bypass member A magnetic circuit composed of the other rolling element and an air gap may be provided. In the case of this configuration, the total area of the contact area that changes depending on the load also increases, so that the sensitivity is improved and the load can be estimated more accurately.

  In this invention, the magnetic circuit may be installed at four locations in the vertical and horizontal directions with respect to at least one row of rolling elements. In the case of this configuration, the magnitudes of loads in various directions can be estimated.

  In this invention, the magnetic circuit may be provided for each of the double row rolling element rows, and these magnetic circuits may be provided between the double row rolling element rows. In the case of this configuration, the load detection sensor structure can be made compact. As described above, even if the magnetic circuits are arranged adjacent to each other, in the present invention, each magnetic circuit is not easily affected by the magnetic flux of the other magnetic circuit, and thus such a magnetic circuit can be arranged.

  In the present invention, the magnetic flux generators of the bypass members installed on the inboard side and the outboard side may generate magnetic fluxes in the same direction. The same direction of magnetic flux here refers to the direction of magnetic flux of the magnetic circuit from the rolling element to the fixed wheel or the direction of magnetic flux of the magnetic circuit from the rolling element to the rotating wheel in the magnetic circuit on the inboard side and the outboard side. Means the same. In the case of this configuration, each magnetic circuit is more unlikely to be affected by the magnetic flux of the other magnetic circuit, so that the load can be estimated more accurately.

  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, a magnetic flux generating unit that generates magnetic flux for at least one row of rolling element rows, And a bypass member having a magnetic flux detection unit for detecting magnetic flux is installed on a peripheral surface portion on the bearing space side of the fixed ring, a part of the fixed ring, at least one rolling element, and the bypass member, At least one magnetic circuit composed of an air gap is provided, and the acting force between the tire and the road surface or the preload amount of the wheel bearing is determined based on the change in magnetic resistance in the magnetic circuit obtained from the detection output of the magnetic flux detection unit. Since the estimation means for estimating the Pact and can be installed load sensors, 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.

  A bypass member 15 serving as a load sensor is provided on a peripheral surface portion on the bearing space side of the outer member 1 that is a fixed ring in the wheel bearing 10, that is, an inner peripheral surface portion. The bypass member 15 includes a magnetic flux generator 16 that generates a magnetic flux and a magnetic flux detector 17 that detects the magnetic flux, as shown in FIG. It is installed for the rolling element row. Specifically, the bypass member 15 is a load sensor that detects a load Fz in the vertical direction (z-axis direction) added to the rolling element row on the outboard side as a part of the acting force between the tire and the road surface. As shown in FIG. 1 and FIG. 2 showing a front view seen from the inboard side of FIG. 1, the rolling surface 4 on the outboard side and the seal 7 on the inner peripheral surface of the outer member 1 It is provided at an upper position and a lower position, respectively. The bypass member 15 at the upper position is used to detect the upward vertical load Fz, and the bypass member 15 at the lower position is used to detect the downward vertical load Fz. In the present embodiment, the vertical load Fz is detected. However, when the bypass member 15 is disposed at the upper position and the lower position, not only the vertical load Fz but also the vehicle width direction (y-axis direction) of the vehicle. Although the load Fy can also be detected, it will be described here as a method of detecting the vertical load Fz.

  As shown in FIG. 3, each of the bypass members 15 in the upper position and the lower position includes a part of the outer member 1 that is a fixed ring, one rolling element 3 in the rolling body row on the outboard side, and an air gap ( A magnetic circuit 19 is configured by the gap 18 between the bypass member 15 and the rolling element 3. If necessary to configure the magnetic circuit 19, a magnetic member may be added as a component of the bypass member 15. The magnetic flux detector 17 of each bypass member 15 is connected to the estimating means 20 as shown in FIG.

  The estimation means 20 is a means for estimating the acting force between the tire and the road surface or the preload amount of the wheel bearing 10 from the change in the magnetic resistance of the magnetic circuit 19, and in this embodiment, the vertical load Fz is estimated. To do. The magnetic resistance of the magnetic circuit 19 varies greatly depending on the presence or absence of the rolling element 3 and also varies depending on the contact area between the rolling element 3 and the rolling surface 4. Since the contact area between the rolling element 3 and the rolling surface 4 changes depending on the load applied to the rolling element 3, the rolling element row is measured by measuring the magnetic resistance when the rolling element 3 passes the installation position of the bypass member 15. Can be estimated. Therefore, the estimation means 20 obtains the magnetic resistance of the magnetic circuit 19 from the magnetic flux detected by the magnetic flux detector 17 of the bypass member 15, and estimates the load Fz from the magnetic resistance. In this case, for example, the estimation means 20 uses a table, an arithmetic expression, or the like that sets the relationship between the magnetic flux detected by the magnetic flux detector 17 and the magnetic resistance of the magnetic circuit 19 and the relationship between the magnetic resistance and the vertical load Fz. The vertical load Fz is detected by comparing the magnetic flux detected by the magnetic flux detector 17 with the relational data.

  In addition, in the magnetic circuit 19 shown in FIG. 3, there is also a circuit 21 that returns through the rolling elements 3 of the inboard rolling element row as shown by a broken line as another path of magnetic flux. Magnetoresistance is large. Therefore, it may be considered that only the change in the contact area between the rolling elements 3 and the rolling surface 4 of the rolling body row on the outboard side affects the change in the magnetic flux detected by the magnetic flux detector 17. Further, since the magnetic resistance in the air gap 18 is larger than that in the other parts, if the air gap 18 can be made as narrow as possible, it becomes easy to detect a change in the contact area between the rolling element 3 and the rolling surface 4.

  FIG. 3 shows an example in which the bypass member 15 is directly attached to the inner peripheral surface of the outer member 1 by bonding or the like. As an attachment structure of the bypass member 15, for example, the bypass member 15 is attached to a ring-shaped attachment member (not shown) made of a non-magnetic material so that the inner peripheral surface of the outer member 1 and the bypass member 15 are in contact with each other. The mounting member may be installed on the inner peripheral surface of the outer member 1 by press fitting or the like.

  Further, in this embodiment, an example in which the bypass members 15 are provided at two locations on the upper and lower sides is shown, but it may be provided at four locations on the upper, lower, left, and right sides. It is possible to estimate loads in various directions such as the load Fy of the load and the load Fx in the front-rear direction (x-axis direction). Further, in FIG. 1, if the outboard side seal 7 is made of a non-magnetic material and the distance between the base of the wheel mounting flange 2a of the hub wheel 2A and the outboard side end of the outer member 1 is sufficiently large, The flow of magnetic flux from the magnetic circuit 19 to the outboard side can be reduced, and the change in the contact area between the rolling element 3 and the rolling surface 4 can be detected more easily. Further, for example, a rolling element detection means (not shown) for detecting the position of the rolling element 3 is separately provided in the vicinity of the installation position of the bypass member 15, and the magnetic flux is detected at a timing when the rolling element detection means detects the rolling element 3. The detection signal of the unit 17 may be captured. In this case, the detection signal of the magnetic flux detector 17 is captured at the timing when the rolling element 3 passes through the installation position of the bypass member 15, that is, the timing at which the magnetic circuit 19 enters the state of FIG. And the change of the contact area of the rolling surface 4 can be detected more easily.

FIG. 4 shows a specific configuration example of the bypass member 15. In this configuration example, the magnetic body 22 is provided on the inner peripheral surface of the outer member 1, and the magnetic body is disposed so as to face the rolling bodies 3 of the rolling board row on the outboard side that passes through the installation portion of the bypass member 15. The member 22 has a magnetic flux generator 16.
Further, a coil that becomes the magnetic flux detection unit 17 is wound around the magnetic member 22. A gap between the end surface of the magnet that becomes the magnetic flux generation unit 16 and the surface of the rolling element 3 becomes an air gap 18 of the magnetic circuit 19. In this case, since the magnetic flux of the magnetic circuit 19 changes every time the rolling element 3 passes through the installation portion of the bypass member 15, an induced voltage generated by a change in the interlinkage magnetic flux in the coil is applied to the coil serving as the magnetic flux detection portion 17. The load can be estimated by measuring and converting this induced voltage into a magnetic resistance. Since this induced voltage also changes depending on the passing speed, it is preferable to calculate the passing speed from the waveform of the induced voltage or a separately installed sensor and correct the induced voltage based on the passing speed.

  FIG. 5 shows another specific configuration example of the bypass member 15. In this configuration example, an L-shaped magnetic body member 22 is formed on the inner peripheral surface of the outer member 1 so that the tip faces the rolling body 3 of the rolling body row on the outboard side that passes through the installation portion of the bypass member 15. The primary coil and the secondary coil to be the magnetic flux generator 16 and the magnetic flux detector 17 are wound around the magnetic member 22. A gap between the end face of the magnetic member 22 and the surface of the rolling element 3 becomes an air gap 18 of the magnetic circuit 19. In this case, an alternating magnetic field is generated by the primary coil 16 serving as the magnetic flux generation unit, and an induced voltage generated by a change in the interlinkage magnetic flux inside the coil is measured by the secondary coil serving as the magnetic flux detection unit 17. The load can be estimated by converting to a magnetic resistance. Further, even if the secondary coil is not wound, it is also possible to detect the change in magnetic resistance as a change in inductance by the primary coil.

  Thus, in this sensor-equipped wheel bearing 10, for at least one rolling element row (here, the rolling body row on the outboard side), the magnetic flux generating section 16 that generates magnetic flux, and the magnetic flux that detects the magnetic flux The bypass member 15 having the detection unit 17 is installed on the peripheral surface (here, the inner peripheral surface) portion of the fixed ring (here, the outer member) 1 on the bearing space side, and a part of the fixed ring 1 and one rolling member are arranged. At least one magnetic circuit 19 including a moving body 3, a bypass member 15, and an air gap 18 is provided, and a tire and a road surface are determined by a change in magnetic resistance in the magnetic circuit 19 obtained from a detection output of the magnetic flux detection unit 17. Therefore, the load applied to the wheels 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.

  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.

FIG. 6 shows a cross-sectional view of the installation portion of the bypass member 15 in the sensor-equipped wheel bearing 10 according to another embodiment of the present invention. In this embodiment, in the previous embodiment, the bypass member 15 has a shape extending over the two rolling elements 3 and 3 adjacent to each other in the circumferential direction of the rolling body row on the outboard side. In this case, the bypass member 15 is installed in an attachment member made of a nonmagnetic material that is fixed to the outer member 1 that is a fixed ring, for example. As a result, as shown in FIG. 7 showing an enlarged view of the portion B in FIG. 6, two magnetic circuits 19, 19 are configured from one bypass member 15. That is, one magnetic circuit 19 includes a part of the outer member 1 that is a fixed ring, one rolling element 3 of two adjacent rolling elements 3, 3, a bypass member 15, and the other one. The rolling element 3 and an air gap (gap between the rolling element 3 and the bypass member 15) 18 are configured. The other magnetic circuit 19 includes a part of the inner member 2 that is a rotating wheel, one of the two adjacent rolling elements 3, 3, the bypass member 15, and the other rolling element 15. The moving body 3 and the air gap 18 are configured.
In this embodiment, as the configuration of the bypass member 15, the configuration example of FIG. 5 in the previous embodiment is shown, but another configuration example may be adopted. Moreover, in this embodiment, the bypass member 15 is installed not only in the vertical position of the rolling element row but also in the horizontal position. Other configurations are the same as those in the previous embodiment.

  Also in the case of this embodiment, in the two magnetic circuits 19 corresponding to each bypass member 15, the magnetoresistance changes due to the change in the contact area between the rolling element 3 and the rolling surfaces 4, 5. By doing so, the load can be estimated.

  FIG. 8 shows still another embodiment of the present invention. In this embodiment, in the embodiment shown in FIGS. 1 to 5, the bypass member 15 is also provided for the inboard-side rolling element row separately from the bypass member 15 for the outboard-side rolling element row. These bypass members 15 are provided between the two rolling element rows. That is, one magnetic circuit constituted by the bypass member 15 and the like for the rolling body row on the outboard side, and the other one magnetic circuit constituted by the bypass member 15 and the like for the rolling body row on the inboard side, It is arranged in parallel between two rows of rolling elements. Other configurations are the same as those of the embodiment of FIGS.

  As described in the previous embodiment, the magnetic circuit composed of the bypass member 15 and the like has a feature that it is not easily affected by the magnetic flux of other magnetic circuits. Even if it is provided so as to be adjacent to each other between the rolling body row on the outboard side and the rolling body row on the inboard side, it does not hinder accurate estimation of the load. Thereby, the sensor of load detection can be comprised compactly.

  In this case, the magnetic flux of the magnetic circuit composed of the bypass member 15 on the outboard side and the magnetic flux of the magnetic circuit composed of the bypass member 15 on the inboard side are not affected by each other. It is desirable that the magnetic flux generation directions in the magnetic circuit on the inboard side are the same. The magnetic flux in the same direction here means the direction of the magnetic flux of the magnetic circuit 19 from the rolling element 3 to the fixed wheel 1 or from the rolling element 3 to the rotating wheel 2 in the magnetic circuit 19 on the inboard side and the outboard side. This means that the magnetic flux direction of the magnetic circuit 19 is the same. Thereby, a load can be estimated more correctly.

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 an expanded sectional view of the A section in FIG. It is an expanded sectional view which shows the specific structural example of a bypass member. It is an expanded sectional view showing other concrete example of composition of a bypass member. It is sectional drawing of the installation part of the bypass member in the bearing for wheels with a sensor which concerns on other embodiment of this invention. It is an expanded sectional view of the B section in FIG. It is a block diagram of the sensor-equipped wheel bearing which concerns on other embodiment of this invention.

Explanation of symbols

1. Outer member (fixed ring)
2 ... Inward member (rotating wheel)
DESCRIPTION OF SYMBOLS 3 ... Rolling elements 4, 5 ... Rolling surface 15 ... Bypass member 16 ... Magnetic flux generation part 17 ... Magnetic flux detection part 18 ... Air gap 19 ... Magnetic circuit 20 ... Estimation means

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,
A bypass member having a magnetic flux generating part for generating magnetic flux and a magnetic flux detecting part for detecting magnetic flux is installed on the peripheral surface part on the bearing space side of the fixed ring, with respect to at least one row of rolling element rows, The magnetic circuit obtained from the detection output of the magnetic flux detection unit by providing at least one magnetic circuit including a part of a fixed ring, at least one rolling element, the bypass member, and an air gap. A sensor-equipped wheel bearing, comprising: an estimation means for estimating an acting force between a tire and a road surface or a preload amount of a wheel bearing from a change in magnetic resistance.   2. The bypass member according to claim 1, wherein the bypass member has a shape extending over two circumferentially adjacent rolling elements, and the fixed ring or the rotating wheel, one of the adjacent two rolling elements, the bypass A wheel bearing with sensor provided with a magnetic circuit composed of a member, another rolling element, and an air gap.   The sensor-equipped wheel bearing according to claim 1 or 2, wherein the magnetic circuit is installed at four positions in the vertical and horizontal directions with respect to at least one row of rolling elements.   The sensor-equipped wheel according to any one of claims 1 to 3, wherein the magnetic circuit is provided for each of the double row rolling element rows, and the magnetic circuit is provided between the double row rolling element rows. Bearings. The sensor-equipped wheel bearing according to claim 4, wherein the magnetic flux generation portions of the bypass members respectively installed on the inboard side and the outboard side generate magnetic fluxes in the same direction.

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