JP2008051282A - Wheel bearing with sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wheel bearing with a sensor wherein a load detecting sensor can be compactly installed in a vehicle in a state of resisting a change of an external environment for consistently detecting a load on a wheel with high sensitivity while reducing cost at mass production. <P>SOLUTION: The wheel bearing comprises an outward member 1 and an inward member 2, and double-row rolling elements 3 laid therebetween. A sensor unit 21 is mounted to a fixed side member out of the outward member 1 and the inward member 2. For example, the fixed side member is the outward member 1. The sensor unit 21 is composed of a sensor mounting member 22, and at least one distortion sensor 23 mounted to the sensor mounting member 22. The sensor unit 21 is covered with a mold member 90. <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 a strain gauge is attached to the outer ring of the wheel bearing to detect the strain (for example, Patent Document 1).
Special table 2003-530565 gazette

  The outer ring of the wheel bearing is a part that has a rolling surface and requires strength, and is a bearing part that is produced through complicated processes such as plastic working, turning, heat treatment, and grinding. When a strain gauge is attached to the outer ring as in Patent Document 1, there is a problem that productivity is poor and the cost for mass production is high. In addition, it is difficult to detect the distortion of the outer ring with high sensitivity, and when the detection result is used for attitude control during vehicle travel, the accuracy of control becomes a problem.

  Therefore, an attempt was made to attach a strain sensor to the sensor attachment member to form a sensor unit, and to attach this sensor unit to the outer peripheral surface of the outer ring. However, since the outer peripheral surface of the outer ring is easily exposed to muddy water when the vehicle is running, when the sensor unit is attached to the outer peripheral surface of the outer ring, the sensor mounting member and Corrosion or deformation may occur in the strain sensor, and the strain sensor may not operate normally.

  The object of the present invention is to install a load detection sensor compactly in a vehicle and in a state that is not easily affected by changes in the external environment, and can always detect the load applied to the wheel with high sensitivity, and the cost for mass production is low. It is providing the wheel bearing with a sensor which becomes.

  The sensor-equipped wheel bearing according to the present invention includes an outer member having a double row rolling surface formed on the inner periphery, an inner member having a rolling surface facing the rolling surface of the outer member, A double row rolling element interposed between both rolling surfaces, and a sealing device that seals an end between the outer member and the inner member, and rotatably supports the wheel with respect to the vehicle body. In the wheel bearing, a sensor mounting unit including a sensor mounting member and at least one strain sensor mounted on the sensor mounting member is mounted on a fixed member of the outer member and the inner member, and the sensor unit is mounted It is characterized by being covered with a mold member. The mold material of the mold member is made of, for example, a polymer material, an elastomer, or a rubber material.

When a load is applied to the rotation side member as the vehicle travels, the fixed side member is deformed via the rolling elements, and the deformation causes distortion of the sensor unit via the mounting member. The strain sensor provided in the sensor unit detects the strain of the sensor unit. If the relationship between strain and load is obtained in advance through experiments and simulations, the load applied to the wheel can be detected from the output of the strain sensor. Moreover, this detected load can be used for vehicle control of an automobile.
Since the wheel bearing has a configuration in which the sensor mounting unit and the sensor unit including the strain sensor mounted on the sensor mounting member are mounted on the fixed side member, the load detection sensor can be compactly installed on the vehicle. In addition, since the sensor unit is covered with the mold member, it is hardly affected by changes in the external environment such as when it is covered with muddy water, and the strain sensor can always detect the deformation of the stationary member with high sensitivity. Since the sensor mounting member is a simple part that can be mounted on the fixed side member, by attaching a strain sensor to the sensor mounting member, the sensor mounting member can be excellent in mass productivity, and the cost can be reduced. In addition, since the member that covers the sensor unit is a mold member, it can be covered easily and with good sealing performance.

The strain sensor is preferably composed of a thick film resistor.
If the strain sensor is composed of a thick film resistor, the strength of mounting the strain sensor on the sensor mounting member does not decrease due to secular change, so that the reliability of the sensor unit can be improved.

  The fixed member can be an outer member. In that case, the sensor unit is attached to the outer peripheral surface of the outer member.

It is preferable to provide an acting force estimating means for estimating an external force acting on the wheel bearing or an acting force between the tire and the road surface by the output of the strain sensor.
By using the external force acting on the wheel bearing obtained by the acting force estimation means or the acting force between the tire and the road surface for vehicle control of the automobile, fine vehicle control is possible.

  The sensor-equipped wheel bearing according to the present invention includes an outer member having a double row rolling surface formed on the inner periphery, an inner member having a rolling surface facing the rolling surface of the outer member, A double row rolling element interposed between both rolling surfaces, and a sealing device that seals an end between the outer member and the inner member, and rotatably supports the wheel with respect to the vehicle body. In the wheel bearing, a sensor mounting unit including a sensor mounting member and at least one strain sensor mounted on the sensor mounting member is mounted on a fixed member of the outer member and the inner member, and the sensor unit is mounted Since it is covered with the mold member, the load detection sensor can be installed in the vehicle compactly and hardly affected by changes in the external environment, and the load applied to the wheel can always be detected with high sensitivity. Since the sensor mounting member is a simple part that can be mounted on the fixed side member, by attaching a strain sensor to the sensor mounting member, the sensor mounting member can be excellent in mass productivity, and the cost can be reduced.

  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.

  This sensor-equipped wheel bearing includes an outer member 1 having a double row rolling surface 3 formed on the inner periphery, an inner member 2 having a rolling surface 4 opposed to each of the rolling surfaces 3, and these It is comprised by the double row rolling element 5 interposed between the rolling surfaces 3 and 4 of the outer member 1 and the inner member 2. This wheel bearing is a double-row angular ball bearing type, and the rolling elements 5 are made of balls and are held by a cage 6 for each row. The rolling surfaces 3 and 4 are arc-shaped in cross section, and each rolling surface 3 and 4 is formed so that the contact angle is outward. Both ends of the bearing space between the outer member 1 and the inner member 2 are sealed by sealing devices 7 and 8, respectively.

The outer member 1 is a fixed side member, and has a flange 1a attached to the knuckle in the suspension device (not shown) of the vehicle body on the outer periphery, and the whole is an integral part. The flange 1a is provided with vehicle body mounting holes 14 at a plurality of locations in the circumferential direction.
The inner member 2 is a rotating side member, and includes a hub wheel 9 having a hub flange 9a for wheel mounting, and an inner ring 10 fitted to the outer periphery of the end portion on the inboard side of the shaft portion 9b of the hub wheel 9. And become. The hub wheel 9 and the inner ring 10 are formed with the rolling surfaces 4 of the respective rows. An inner ring fitting surface 12 having a small diameter with a step is provided on the outer periphery of the inboard side end of the hub wheel 9, and the inner ring 10 is fitted to the inner ring fitting surface 12. A through hole 11 is provided at the center of the hub wheel 9. The hub flange 9a is provided with press-fitting holes 15 for hub bolts (not shown) at a plurality of locations in the circumferential direction. In the vicinity of the base portion of the hub flange 9a of the hub wheel 9, a cylindrical pilot portion 13 for guiding a wheel and a brake component (not shown) protrudes toward the outboard side.

A sensor unit 21 shown in FIG. 3 is provided on the outer peripheral portion of the outer member 1. The sensor unit 21 is obtained by attaching a strain sensor 23 for measuring the strain of the sensor attachment member 22 to the sensor attachment member 22. The sensor unit 21 is attached to the outer member 1 via the first and second attachment members 40 and 41.
The sensor mounting member 22 includes a first contact fixing portion 22a that is fixed in contact with the first mounting member 40, and a second contact fixing portion 22b that is fixed in contact with the second mounting member 41. ing. The sensor mounting member 22 is configured in an L shape with a radial portion 22c along the radial direction and an axial portion 22d along the axial direction, and the distal end side of the radial portion 22c is the first contact. A fixing portion 22a is provided, and a tip end side of the axial portion 22d is the second contact fixing portion 22b. The radial portion 22c is thinned so as to be less rigid than the axial portion 22d. The strain sensor 23 is attached to the radial portion 22c having low rigidity.
The first mounting member 40 is contact-fixed in the vicinity of the sensor unit-side contact fixing portion 40 a fixed to the first contact fixing portion 22 a of the sensor mounting member 22 and the vehicle body mounting hole 14 of the outer member 1. And an outer member side contact fixing portion 40b. Further, the second mounting member 41 includes a sensor unit side contact fixing portion 41 a fixed to the second contact fixing portion 22 b of the sensor mounting member 22 and an outer surface fixed to the outer peripheral surface of the outer member 1. And a member-side contact fixing portion 41b.

  For example, as shown in FIG. 4, the strain sensor 23 is formed of a thick film resistor on the sensor mounting surface 22 </ b> A of the sensor mounting member 22. That is, an insulating layer 50 is formed on the sensor mounting surface 22A, and electrodes 51, 51 made of thick film resistors are formed on both sides of the surface of the insulating layer 50, and the electrode 51, 51 is formed between the electrodes 51, 51. A strain measurement resistor 52 made of a thick film resistor serving as a strain sensor is formed on the insulating layer 50, and a protective film 53 is formed on the electrodes 51 and 51 and the strain measurement resistor 52. It has become.

  A method for manufacturing the sensor unit 21 will be described below. First, the insulating layer 50 is formed by printing and baking an insulating material such as glass on the surface of the sensor mounting member 22 formed of a metal material such as stainless steel. Next, a conductive material is printed and baked on the surface of the insulating layer 50 to form the electrodes 51 and 51. Further, a strain measurement resistor 53 is formed by printing and baking a material to be a resistor between the electrodes 51 and 51. Further, a protective film 53 is formed to protect the electrodes 51 and 51 and the strain measuring resistor 52.

  As the strain sensor 23, various sensors can be used in addition to the one formed by the thick film resistor. For example, the strain sensor 23 can be composed of a metal foil strain gauge. In that case, the sensor attachment member 22 is usually fixed by adhesion.

  As shown in FIGS. 1 and 2, the sensor unit 21 has first and second contact fixing portions 22a and 22b of the sensor mounting member 22 outwardly by first and second mounting members 40 and 41, respectively. The outer member 1 is fixed to the outer peripheral portion so as to be in the same phase with respect to the circumferential direction of the member 1. The sensor attachment member 22, the first and second attachment members 40 and 41, and the outer member 1 are fixed by, for example, bonding with an adhesive. When the first and second contact fixing portions 22a and 22b are in the same phase in the circumferential direction, the sensor mounting member 22 can be shortened, so that the sensor unit 21 can be easily installed.

  Further, after the sensor unit 21 is fixed to the outer member 1, the mold unit 90 covers the periphery of the sensor unit 21 and the mounting members 40 and 41. As a material of the mold member 90, for example, a polymer material, an elastomer, a rubber material, or the like can be preferably used. The mold member 90 is molded by, for example, placing a molding die (not shown) covering the sensor unit 21 on the outer member 1, pouring molten mold material into the molding die and curing it. The mold member 90 may be formed by coating.

  As shown in FIG. 1, acting force estimating means 31 and abnormality determining means 32 are provided as means for processing the output of the strain sensor 23. These means 31 and 32 may be provided in an electronic circuit device (not shown) on a circuit board or the like attached to the outer member 1 of the wheel bearing, or may be an electric control unit of an automobile. (ECU) may be provided.

The operation of the sensor-equipped wheel bearing with the above configuration will be described. When a load is applied to the hub wheel 9, the outer member 1 is deformed via the rolling elements 5. The deformation of the outer member 1 is transmitted to the sensor mounting member 22 via the first and second mounting members 40 and 41, and the sensor mounting member 22 is deformed. The strain of the sensor mounting member 22 is measured by the strain sensor 23. At this time, the radial portion 22 c of the sensor mounting member 22 is deformed according to the deformation of the flange 1 a of the outer member 1. In the case of this embodiment, the radial portion 22c is lower in rigidity than the outer member 1, and the sensor mounting member 22 is an L-shape configured by a radial portion 22c having low rigidity and an axial portion 22d having high rigidity. Therefore, distortion concentrates in the vicinity of the corner portion 22e on the radial direction portion 22c side between the radial direction portion 22c and the axial direction portion 22d, and appears as distortion larger than that of the outer member 1. That is, the distortion generated between the radial part 22c and the axial part 22d is a distortion obtained by transferring and expanding the distortion of the R portion 1b at the proximal end of the flange 1a. Since this strain is measured by the strain sensor 23, the strain of the outer member 1 can be detected with high sensitivity, and the strain measurement accuracy is increased.
Since the sensor unit 21 is protected by the mold member 90, the sensor unit 21 is less affected by changes in the external environment. For example, even if the outer member 1 is covered with muddy water, the sensor unit 21 is not affected. Specifically, the sensor mounting member 22 and the strain sensor 23 are not corroded or deformed. For this reason, the strain sensor 23 can always detect the deformation of the outer member 1 with high sensitivity.

  Since the strain changes depending on the direction and magnitude of the load, if the relationship between the strain and the load is obtained in advance through experiments and simulations, the external force acting on the wheel bearing or the acting force between the tire and the road surface is calculated. be able to. From the relationship between the strain and the load obtained and set in advance through experiments and simulations, the acting force estimation means 31 determines the external force acting on the wheel bearing or the distance between the tire and the road surface from the output of the strain sensor 23. Is calculated. The abnormality determining means 32 outputs an abnormality signal to the outside when it is determined that the external force acting on the wheel bearing calculated by the acting force estimating means 31 or the acting force between the tire and the road surface exceeds an allowable value. Output. This abnormal signal can be used for vehicle control of an automobile. In addition, when an external force acting on the wheel bearing in real time or an acting force between the tire and the road surface is output, finer vehicle control becomes possible.

  This wheel bearing has a configuration in which the sensor unit 21 including the sensor attachment member 22 and the strain sensor 23 attached to the sensor attachment member 22 is attached to the outer member 1, so that the load detection sensor is compactly installed in the vehicle. it can. Further, since the sensor unit 21 is not directly attached to the outer member 1 but is attached to the outer member 1 via the first and second attachment members 40 and 41, the sensor attachment member 22 is L The shape can be a simple shape. If the sensor mounting member 22 has a simple shape, the sensor mounting member 22 can be easily processed, and the cost can be reduced. Further, when the sensor mounting member 22 has a simple shape, the fixed position of the strain sensor 23 can be accurately positioned. In the case of this embodiment, since the surface on which the strain sensor 23 is provided in the sensor mounting member 22 is a flat surface, it is easy to form the strain sensor 23 on the sensor mounting member 22 with a pressure film resistor.

  When the strain sensor 23 is composed of a metal foil strain gauge or the like, the sensor mounting member 22 is usually fixed by adhesion. However, in fixing by bonding, a decrease in bonding strength due to secular change may affect the detection of the strain sensor 23. Moreover, since time is required for the bonding operation, it also causes an increase in cost. On the other hand, as shown in FIG. 4, when the strain sensor 23 is a sensor unit 21 formed of a thick film resistor on the sensor mounting surface 22 </ b> A of the sensor mounting member 22, there is almost no decrease in adhesive strength due to aging. Therefore, the reliability can be improved. Further, since the bonding work of the strain sensor 23 is not necessary, the assembling workability can be improved and the cost can be reduced.

  In the above-described embodiment, the sensor unit 21 is provided only at one place on the outer member 1. However, for example, as illustrated in FIG. 5, the sensor unit 21 may be provided at two or more places. Even when the sensor units 21 are provided at two or more locations, each sensor unit 21 is covered with the mold member 90. If the sensor unit 21 is provided at two or more places, it becomes possible to detect a load with higher accuracy.

  6 and 7 show different embodiments. In the wheel bearing, the sensor mounting member 22, the first and second mounting members 40 and 41, and the outer member 1 are fixed using bolts. The sensor mounting member 22 has the same overall shape as the sensor mounting member 22 shown in FIG. 3, the first contact fixing portion 22a is formed with an axial bolt insertion hole 70, and the second contact fixing portion 22b. A bolt insertion hole 71 is formed in the radial direction. The first mounting member 40 has a bolt insertion hole 72 corresponding to the bolt insertion hole 70, and the second mounting member 41 has a bolt insertion hole 73 corresponding to the bolt insertion hole 71. Is formed. Further, in the outer member 1, bolt screw holes 74 and 75 each having an internal thread formed on the inner peripheral surface thereof correspond to the positions corresponding to the bolt insertion holes 70 and 72 and the bolt insertion holes 71 and 73. Each is formed at a position.

  As shown in FIG. 6, the sensor unit 21 includes a bolt 76 inserted from the outboard side into the bolt insertion hole 70 of the sensor attachment member 22 and the bolt insertion hole 72 of the first attachment member 40, and a male screw of the bolt 76. The portion 76 a is screwed into the bolt screw hole 74 of the outer member 1, and the bolt 76 is inserted from the outer peripheral side into the bolt insertion hole 71 of the sensor attachment member 22 and the bolt insertion hole 73 of the second attachment member 41. The external thread 1 is fixed to the outer member 1 by screwing the male thread portion 76 a of the bolt 76 into the bolt screw hole 75 of the outer member 1. Further, as described above, after the sensor unit 21 is fixed to the outer member 1, the mold unit 90 covers the sensor unit 21 and the mounting members 40 and 41.

  For fixing the sensor mounting member 22, the first and second mounting members 40 and 41, and the outer member 1, either an adhesive or a bolt may be used. Moreover, you may use both together. Furthermore, you may fix the sensor attachment member 22 and the outward member 1 by welding, without using an adhesive agent and a volt | bolt. Whichever of these fixing structures is adopted, the sensor mounting member 22, the first and second mounting members 40 and 41, and the outer member 1 can be firmly fixed. Therefore, the sensor mounting member 22 is not displaced with respect to the outer member 1, and the deformation of the outer member 1 can be accurately transmitted to the sensor mounting member 22.

  In each of the above-described embodiments, the sensor unit 21 is fixed to the outer member 1 and then covered with the mold member 90. However, the sensor unit 21 having the mounting members 40 and 41 fixed thereto is previously covered with the mold member 90. Alternatively, this may be fixed to the outer member 1.

In each of the above embodiments, the case where the outer member 1 is a fixed side member has been described. However, the present invention can also be applied to a wheel bearing in which the inner member is a fixed side member. The sensor unit 21 is provided on the peripheral surface that is the inner periphery of the inner member.
In each of the above embodiments, the case where the present invention is applied to a third generation type wheel bearing has been described. However, the present invention is for a first or second generation type wheel in which the bearing portion and the hub are independent parts. The present invention can also be applied to a bearing or a fourth-generation type wheel bearing in which a part of the inner member is composed of an outer ring of a constant velocity joint. Further, this sensor-equipped wheel bearing can be applied to a wheel bearing for a driven wheel, and can also be applied to a tapered roller type wheel bearing of each generation type.

It is a figure showing combining the sectional view of the wheel bearing with a sensor concerning the embodiment of this invention, and the block diagram of the conceptual composition of the detection system. It is a front view which shows the outward member and sensor unit of the wheel bearing with a sensor. (A) is the top view which separated and displayed the sensor unit and the 1st, 2nd member for attachment, (B) is the side view. It is a figure which shows the cross-section of a sensor unit. It is a front view which shows the outward member and sensor unit of a different wheel bearing with a sensor. It is sectional drawing of the bearing for wheels with a sensor concerning different embodiment of this invention. (A) is the top view which displayed the sensor unit of the wheel bearing with a sensor and the 1st, 2nd attachment member isolate | separated mutually, (B) is the VIIB-VIIB sectional drawing.

Explanation of symbols

1 ... Outer member (fixed side member)
2 ... Inward member (rotary member)
3, 4 ... rolling surface 5 ... rolling elements 7, 8 ... sealing device 21 ... sensor unit 22 ... sensor attachment member 23 ... strain sensor 31 ... acting force estimation means 32 ... abnormality determination means 40 ... first attachment member 41 ... Second mounting member 90 ... Mold member

Claims (7)

An outer member in which a double row rolling surface is formed on the inner periphery, an inner member having a rolling surface opposite to the rolling surface of the outer member, and a double row interposed between both rolling surfaces A rolling bearing, and a sealing device that seals an end between the outer member and the inner member, and a wheel bearing that rotatably supports a wheel with respect to a vehicle body,
A sensor unit comprising a sensor attachment member and at least one strain sensor attached to the sensor attachment member is attached to a fixed side member of the outer member and the inner member, and the sensor unit is covered with a mold member. A wheel bearing with a sensor characterized by the above.   2. The wheel bearing with sensor according to claim 1, wherein the strain sensor is formed of a thick film resistor.   The sensor-equipped wheel bearing according to claim 1 or 2, wherein a mold material of the mold member is a polymer material.   3. The wheel bearing with sensor according to claim 1, wherein the molding material of the molding member is an elastomer.   3. The wheel bearing with sensor according to claim 1, wherein the molding material of the molding member is a rubber material.   The sensor-equipped wheel bearing according to claim 1, wherein the fixed side member is an outer member.   7. The sensor-equipped wheel according to claim 1, further comprising an acting force estimating means for estimating an external force acting on a wheel bearing or an acting force between a tire and a road surface based on an output of the strain sensor. Bearings.

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