JP2008185496A - Bearing apparatus for wheel with sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bearing apparatus for wheels with sensors capable of easily and accurately detecting the state of load of bearings. <P>SOLUTION: In the bearing apparatus for wheels in which double-row rolling elements are interposed between an outer member and an inner member, a distortion sensor 21 and a processing circuit 40 are mounted to a fixed-side member among the outer member and the inner member. The distortion sensor 21 includes both a distortion generating member fixed to the fixed-side member and a sensor element 23 for distortion measurement mounted to the distortion generating member. The processing circuit 40 processes distortion signals output from the sensor element 23 of the distortion sensor 21. The processing circuit 40 has an offset regulating means 42 for regulating offset of output of the sensor element 23. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a sensor-equipped wheel bearing device incorporating a 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 measuring sensor element to the strain generating member to form a strain sensor, and to attach the strain sensor to the outer ring. As a result of trial and error, in order to improve the detection sensitivity of the outer ring distortion, the strain generating member has two contact fixing parts with respect to the outer ring, and one of these contact fixing parts is provided with one of the contact fixing parts. It has been found that it is better to fix to the flange surface of the outer ring and fix the other contact fixing part to the outer peripheral surface of the outer ring.

However, even with such a configuration, there are the following problems.
-When the strain sensor is fixed to the outer ring or the like with a bolt or the like, the force causes deformation of the sensor member, and the offset of the sensor signal changes depending on the mounting state.
• When the sensor element is made of a thick film resistor, etc., there is an offset due to manufacturing variations, and output variations with a strain sensor attached to the bearing cannot be suppressed.
The amount of strain due to the bearing load that is to be detected by the strain sensor is very small due to the high rigidity of the bearing, and it is necessary to remove the offset generated for the above reasons from the sensor signal before amplification.

  An object of the present invention is to provide a wheel bearing device with a sensor that can easily and accurately detect a load state of a bearing.

The sensor-equipped wheel bearing device 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 respective rolling surfaces on the outer periphery, In a wheel bearing device comprising a rolling element having a double-row rolling surface interposed between the rolling surfaces of the row, and rotatably supporting the wheel with respect to the vehicle body,
A strain generating member including a strain generating member fixed to a fixed side member of the outer member and the inner member, a strain measuring sensor element attached to the strain generating member, and the sensor element of the strain sensor And a processing circuit for processing the distortion signal output from
This processing circuit has an offset adjusting means for adjusting an offset of the output of the sensor element.
According to this configuration, since the offset of the output of the sensor element in the strain sensor is adjusted by the offset adjusting means of the processing circuit, the sensor output can be adjusted, for example, by zero adjustment in the assembled state of the wheel bearing device with sensor. it can. Thereby, the sensor output value in the state where the load is not applied with the single-piece | unit of the wheel bearing apparatus with a sensor can be grasped | ascertained correctly. In addition, it is possible to correct the sensor element characteristic variation and the strain sensor mounting distortion together. As a result, the load signal detected by the bearing device is output in a properly calibrated state, and the load state of the bearing can be obtained easily and accurately on the vehicle body side using the signal.

  In the present invention, the offset adjusting means may be any one of a variable resistor, a circuit having a laser trimming resistor element, or a microcomputer having a setting value storage function for offset adjustment. When the offset adjusting means is any one of the above, the offset adjustment can be performed with a simple configuration with high accuracy.

  In this invention, the fixed side member may be an outer member, and the strain generating member may be attached to the outer member. In the case of an outer member, since it becomes an annular member, an attachment location is easy to obtain compared with an inner member.

As described above, when the fixed side member is an outer member and the strain generating member is attached to the outer member, the mounting force of the fixed side member to the vehicle body is detected by the output of the sensor. There is provided a vehicle body attachment force detecting means and an attachment abnormality determining means for determining whether or not the attachment force detected by the vehicle body attachment force detection means is within a set range and outputting an alarm signal if it is outside the set range. Also good.
When the attachment force of the stationary member to the vehicle body changes, the strain of the strain generating member fixed to the stationary member changes. Therefore, the attachment force of the stationary member to the vehicle body can be detected by the output of the sensor. In this way, the attachment force can be detected, and when the stationary member is attached to the vehicle body with an abnormal attachment force, an alarm signal is output from the attachment abnormality determination means, so the abnormality in the attachment state can be known by the alarm signal. . Further, the determination of the attachment abnormality determination means can be used as a quality control reference for the sensor state. Furthermore, since the mounting state of the sensor-equipped wheel bearing device to the vehicle body can be managed, more accurate load measurement is possible.

  The sensor-equipped wheel bearing device 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 respective rolling surfaces on the outer periphery, And a rolling element having a double-row rolling surface interposed between the rolling surfaces of the row, wherein the wheel bearing device supports the wheel rotatably with respect to the vehicle body. A strain generating member fixed to the fixed side member of the sensor, a strain sensor including a sensor element for strain measurement attached to the strain generating member, and a processing circuit for processing a strain signal output from the sensor element of the strain sensor The processing circuit has offset adjusting means for adjusting the offset of the output of the sensor element, so that the load signal detected by the bearing is output after being properly calibrated by the processing circuit. Body to use In can be obtained accurately and simply load condition of the bearing.

  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.

  The bearing device in this sensor-equipped wheel bearing device includes an outer member 1 in which double-row rolling surfaces 3 are formed on the inner periphery, and an inner member in which rolling surfaces 4 that face the respective rolling surfaces 3 are formed. 2 and double row rolling elements 5 interposed between the rolling surfaces 3 and 4 of the outer member 1 and the inner member 2. This wheel bearing device is a double-row angular ball bearing type, and the rolling elements 5 are formed 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 strain sensor 21 and a sensor signal processing circuit unit 25 having a sensor signal processing circuit are provided on the outer peripheral portion of the outer member 1 which is a fixed side member. The strain sensor 21 is obtained by attaching a sensor element 23 or the like for measuring the strain of the strain generating member 22 to the strain generating member 22.

  One structural example of the strain sensor 21 is shown in FIG. In the strain sensor 21, the strain generating member 22 includes a first contact fixing portion 22 a that is fixed to the flange surface of the flange 1 a of the outer member 1 in the vicinity of the vehicle body mounting hole 14, and an outer peripheral surface of the outer member 1. And a second contact fixing portion 22b fixed to the contact. The strain generating member 22 includes a radial portion 22c along the radial direction including the first contact fixing portion 22a and an axial portion 22d along the axial direction including the second contact fixing portion 22b. It is configured in an L shape. The radial portion 22c is thinned so as to be less rigid than the axial portion 22d. The strain measuring sensor element 23 is attached to the low-rigidity radial portion 22c.

  As shown in FIGS. 1 and 2, the strain sensor 21 includes the first and second contact fixing portions 22 a and 22 b of the strain generating member 22 so that both contact fixing portions 22 a and 22 b are in the circumferential direction of the outer member 1. Are fixed to the outer peripheral portion of the outer member 1 so as to be in the same phase. When the first and second contact fixing portions 22a and 22b are in the same phase in the circumferential direction, the strain generating member 22 can be shortened, so that the strain sensor 21 can be easily installed. The strain measuring sensor element 23 is fixed to the strain generating member 22 using, for example, an adhesive.

  The strain generating member 22 has a shape or material that does not cause plastic deformation by being fixed to the outer member 1. Further, the strain generating member 22 needs to have a shape that does not cause plastic deformation even when the maximum expected load is applied to the wheel bearing device. The above assumed maximum force is the maximum force assumed in traveling that does not lead to vehicle failure. This is because, when plastic deformation occurs in the strain generating member 22, the deformation of the outer member 1 is not accurately transmitted to the strain generating member 22 and affects the measurement of strain.

The strain generating member 22 of the strain sensor 21 can be manufactured from a metal material such as a steel material, for example, by pressing. If the strain generating member 22 is a press-processed product, the cost can be reduced.
Further, the strain generating member 22 may be a sintered metal product by metal powder injection molding. Metal powder injection molding is one of the molding techniques for metals, intermetallic compounds, etc., a step of kneading metal powder with a binder, a step of injection molding using this kneaded product, a step of degreasing the molded body, Including a step of sintering the compact. According to this metal powder injection molding, a sintered body having a higher sintering density than that of general powder metallurgy can be obtained, and sintered metal products can be manufactured with high dimensional accuracy, and mechanical strength is also high. There are advantages.

  As the strain measuring sensor element 23, various elements can be used. For example, when the strain measuring sensor element 23 is composed of a metal foil strain gauge, considering the durability of the metal foil strain gauge, even when the maximum expected load is applied to the wheel bearing device, It is preferable that the strain amount of the attachment portion of the strain measuring sensor element 23 in the strain generating member 22 is 1500 microstrain or less. For the same reason, when the strain measuring sensor element 23 is composed of a semiconductor strain gauge, the strain amount is preferably 1000 microstrain or less. Further, when the strain measuring sensor element 23 is constituted by a thick film type sensor, the amount of strain is preferably 1500 microstrain or less.

  FIG. 5 shows another configuration example of the strain sensor 21. In the strain sensor 21, a plate member is bent into an L shape to form a strain generating member 22, and bolt insertion holes 31 and 32 are formed in the radial piece 22A and the axial piece 22B, respectively. The strain measuring sensor element 23 is fixed to one surface of the radial piece 22A. As shown in FIG. 6, the strain generating member 22 is fastened to the outer peripheral portion of the outer member 1 with bolts 39 via two contact fixing members 33 and 34. That is, the bolt 39 inserted from the bolt insertion hole 31 of the radial piece 22A into the bolt insertion hole 35 of the first contact fixing member 33 is applied to the flange surface in the vicinity of the vehicle body mounting hole 14 in the flange 1a of the outer member 1. A bolt 39 is provided on the outer peripheral surface of the outer member 1 and is screwed into the screw hole 37 and inserted into the bolt insertion hole 36 of the second contact fixing member 34 from the bolt insertion hole 32 of the axial piece 22B. The strain generating member 22 is fastened to the outer member 1 by being screwed into the screw hole 38.

  In the strain sensor 21 of FIG. 5, four strain measuring sensor elements 23 are arranged on the radial piece 22 </ b> A of the strain generating member 22. In this case, the distortion of the distortion generating member 22 tends to increase from the fixed portion toward the bent corner portion 22C, and it is desirable to dispose the strain measuring sensor element 23 as close to the bent corner portion 22C as possible. As shown in the graph of FIG. 7 as a result of the calculation, when the thickness x of the strain generating member 22 is t, and the distance x from the bent corner portion 22C to the sensor element arrangement position is in the range of x <3t, it is efficient. It has been found that distortion can be detected.

  In view of this, in the strain sensor 21, two strain measurement sensor elements 23 are disposed in a portion of the strain generating member 22 that receives the strain in the radial piece 22A (portion close to the bent corner portion 22C), and is further affected by the strain. The other two strain measuring sensor elements 23 are arranged in a portion (a portion far from the bent corner portion 22C) that is not present.

  FIG. 8 shows still another configuration example of the strain sensor 21. In the strain sensor 21, in the strain sensor 21 of FIG. 5, two strain measurements having the same characteristics or different characteristics are applied to a portion (a portion close to the bent corner portion 22 </ b> C) that receives the strain in the radial piece 22 </ b> A. The sensor element 23 for distortion is arranged, and the sensor element 23 for distortion measurement is not arranged in a part not affected by the distortion (a part far from the bent corner part 22C). Other configurations are the same as those of the strain sensor 21 of FIG.

  As shown in FIG. 3, the sensor signal processing circuit unit 25 has a circuit board 27 made of glass epoxy or the like in a housing 26 made of resin or the like. An operational amplifier, a resistor, a microcomputer, etc., which are circuit components of the processing circuit 40 (FIG. 9) for processing the output signal of the measurement sensor element 23, and an electric / electronic component 28 for power supply that drives the strain measurement sensor element 23, etc. Is arranged. Further, a joint portion 29 is provided for joining the wiring such as the strain measuring sensor element 23 and the circuit board 27. In addition, it has a cable 30 for supplying power from the outside and outputting an output signal processed by the processing circuit 40 to the outside.

  FIG. 9 is a block diagram showing a configuration example of the processing circuit 40 in the sensor signal processing circuit unit 25. The processing circuit 40 includes an amplifier circuit 41, an offset adjustment circuit 42, a storage unit 43, various correction circuits 44, an external interface 45, a signal output circuit 46, and a control circuit 47. The control circuit 47 is a control circuit that controls any of the offset adjustment circuit 42, the storage unit 43, the correction circuit 44, and the signal output circuit 46.

FIG. 10 shows an example of a connection configuration between the detection circuit of the strain sensor 21 and the amplification circuit 41 that amplifies the output signal. The strain sensor 21 in this case is of the configuration example shown in FIGS. 5 and 6, and the detection circuit has two strain measurement sensor elements 23 (S 1) at the position where the strain is received and the influence of the strain. Two strain measurement sensor elements 23 (S2) at positions not received are bridge-connected. The amplifier circuit 41 is composed of an operational amplifier. A fixed resistor may be provided in place of the two strain measuring sensor elements 23 (S2) at positions not affected by the strain.
In this way, the two strain measurement sensor elements 23 (S1) at the position where the distortion is received and the two strain measurement sensor elements 23 (S2) at the position where the distortion is not affected are bridge-connected to form a detection circuit. When configured, the distortion signal output has twice the amplitude and the detection sensitivity can be increased. Basically, the load applied to the wheel bearing device can be detected by a signal obtained by amplifying the distortion signal output by the amplifier circuit 41, that is, only by the configuration of the portion A in the circuit of FIG.

  However, when the strain-measuring sensor element 23 of the strain sensor 21 is made of, for example, a thick film resistor, there is a manufacturing variation, and therefore an initial offset due to individual differences occurs in the output signal of the strain sensor 21. Further, when the strain sensor 21 has the structure shown in FIGS. 5 to 8, for example, the bolt 39 is used to fasten the strain generating member 22 to the wheel bearing device (the outer member 1 in this case). The distortion due to the fixing force applied with the fastening is applied to the distortion generating member 22, and the output signal of the distortion sensor 21 is further changed by the distortion. These offsets are usually larger than the distortion signal of the bearing device to be detected. Therefore, in order to increase the gain of the strain signal of the bearing device to be detected in the amplification circuit 41 at the next stage of the strain sensor 21, it is necessary to remove the offset included in the output signal of the strain sensor 21.

The offset adjustment circuit 42 in the processing circuit 40 adjusts the initial offset of the strain sensor 21 and the offset due to fixing to the wheel bearing device to normal values, and is adjusted by the control circuit 47 or externally. It is configured to be able to adjust the offset according to the command.
As described above, the cause of the offset is the variation of the strain sensor 21 and the strain when the sensor is fixed. Therefore, it is desirable to attach the strain sensor 21 to the wheel bearing device and adjust the offset when the assembly is completed. .

FIG. 11 shows a specific connection configuration example of the strain sensor 21, the amplifier circuit 41, and the offset adjustment circuit 42. In this configuration example, the offset adjustment circuit 42 is configured as an adder / subtracter including an operational amplifier OP, resistors R3 and R4, variable resistors VR1 and VR2, and the like. In the case of this offset adjustment circuit 42, the resistance values of the variable resistors VR1 and VR2 are adjusted and fixed so that the sensor output becomes a specified value (zero point voltage) after the assembly of the wheel bearing device with sensor is completed.
In this offset adjustment circuit 42, a laser trimming resistor element may be used instead of the variable resistors VR1 and VR2. When the offset adjustment circuit 42 is configured by a microcomputer or the like, an operation equivalent to the operation for adjusting the resistance values of the variable resistors VR1 and VR2 described above is executed by software, and the setting value is stored in the storage unit 43. You may do it.

  Thus, after the assembly of the sensor-equipped wheel bearing device is completed, when the offset is adjusted by the offset adjustment circuit 42 so that the sensor output of the strain sensor 21 becomes a specified value, the sensor-equipped wheel bearing device is a completed product. Since the sensor output at the time can be set to the zero point voltage, it is possible to ensure the quality of the sensor signal of the single wheel bearing device with sensor.

Although not shown in the strain sensor 21 illustrated in FIG. 5 to FIG. 8, a temperature sensor element may be provided in the strain generating member 22, and in this case, the sensor offset is determined based on the output of the temperature sensor element. Automatic compensation can be performed by the control circuit 47.
For example, in the case of the offset adjustment circuit 42 in FIG. 11, temperature control of the offset value can be performed by inputting the control voltage e1 corresponding to the detection output of the temperature sensor element from the control circuit 47 to the terminal T1.

  In the circuit configuration example of FIG. 11, the strain sensor 21 having the configuration shown in FIG. 8 is used as the strain sensor 21. In this case, two strain measuring sensor elements 23 (S1) and 23 (S2) having different characteristics, which are arranged at positions to receive strain in the radial piece 22A of the strain generating member 22, are two fixed resistors R1 and R2. Configured by bridge connection. In this case, a distortion signal output having an amplitude obtained by adding the outputs of the two strain measurement sensor elements 23 (S1) and 23 (S2) can be obtained.

The storage means 43 is composed of, for example, a non-volatile memory, and stores parameters for correcting the temperature characteristics, sensitivity, and nonlinearity of the offset. The control circuit 47 controls the correction processing of various correction circuits 44 based on these parameters.
For example, since the output characteristic of the strain sensor 21 has a non-linear relationship with the load applied to the wheel bearing device, this characteristic data is tabulated and stored in the storage means 43, or the storage means 43 in the form of an approximate curve parameter. To remember. The control circuit 47 reads the nonlinear correction data stored in the storage unit 43 and controls the operation of the linear correction circuit prepared as one of the correction circuits 44 to execute the nonlinear correction process. The offset temperature correction and sensitivity correction are performed in the same manner.

  The external interface 45 is a means for performing communication with the control circuit 47 from the outside, and includes a signal terminal, a wireless communication means, and the like. The correction data stored in the storage unit 43 can be corrected from the outside via the external interface 45.

  The signal output circuit 46 performs various conversions such as pulse modulation, frequency modulation, A / D conversion, and conversion to serial data on the output signal of the distortion sensor 21 corrected by the offset adjustment circuit 42 and various correction circuits 44. Go and output to the outside.

  Thus, in this wheel bearing device with a sensor, the strain generating member 22 fixed to the fixed member (here, the outer member 1) of the outer member 1 and the inner member 2, and the strain generating member. 22, a strain sensor 21 including a strain measurement sensor element 23 attached to 22, and a processing circuit 40 that processes a strain signal output from the sensor element 23 of the strain sensor 21. Since the offset adjustment circuit 42 for adjusting the offset of the output of the sensor element 23 is provided, the load signal detected by the bearing device is output in a properly calibrated state, and the load state of the bearing is used on the vehicle body side using the signal. Can be obtained easily and accurately.

  FIG. 12 is a graph showing the relationship between the output voltage of the strain sensor 21 and the tightening force of the mounting bolt when the sensor-equipped wheel bearing device is mounted on the vehicle body. Thus, the output characteristics of the strain sensor 21 vary depending on the state of attachment to the vehicle body. That is, when the wheel bearing device with sensor is fixed to the vehicle body with the mounting bolt, distortion due to fixation is generated in the bearing device, and the distortion is transmitted to the strain generating member 22 of the strain sensor 21, whereby the output of the strain sensor 21. The characteristic changes.

  Thus, there is a variation in the fixing force for attaching the wheel bearing device with sensor to the vehicle body, and the amount of change in the output characteristics of the strain sensor 21 is not constant. Therefore, in order to more accurately measure the load applied to the bearing device, the sensor output when the vehicle is in a normal posture / state is stored in advance in an electric control unit (ECU) or the like on the vehicle body side. The load applied to the bearing device during use of the vehicle may be measured by comparing the sensor output during use with the stored sensor output value to determine the amount of change. Further, the functional unit that executes these processes may be mounted inside the control circuit 47 in the processing circuit 40 of FIG. 9, for example. In this sensor-equipped wheel bearing device, as described above, the sensor output of the sensor-equipped wheel bearing device alone is adjusted before being attached to the vehicle body, so the amount of change in sensor output from there is not large, The above processing can be easily performed.

FIG. 13 shows another configuration example of the processing circuit 40. In this configuration example, a vehicle body attachment force detection means 48 and an attachment abnormality determination means 49 are further added to the processing circuit 40 of FIG. Other configurations are the same as those in FIG.
The vehicle body attachment force detecting means 48 detects the attachment force of the stationary side member (here, the outer member 1) of the sensor-equipped wheel bearing device to the vehicle body from the output of the strain sensor 21. The attachment abnormality determination means 49 determines whether or not the attachment force detected by the vehicle body attachment force detection means 48 is within a set range, and outputs an alarm signal if it is outside the set range.

  For example, in the graph of FIG. 12, the sensor output voltage of the single wheel bearing device with sensor is adjusted to V0. When the minimum value of the setting range of the mounting force is F1 and the maximum value is F2, the sensor output voltage is in the range of V1 to V2. Therefore, when a sensor output voltage outside this range is output, the mounting abnormality determination means 49 determines that the mounting force is abnormal and outputs an alarm signal.

  When the processing circuit 40 is configured in this way, the determination of the attachment abnormality determination unit 49 can be used as a quality control reference for the sensor state. Moreover, since the attachment state to the vehicle body of the wheel bearing apparatus with a sensor can be managed, more accurate load measurement is possible.

It is sectional drawing of the wheel bearing apparatus with a sensor concerning one Embodiment of this invention. It is a front view of the outward member of the bearing device for wheels with the sensor. It is a side view of a sensor signal processing circuit unit. (A) is a side view of a configuration example of a strain sensor, and (B) is a view taken along the arrow IV. (A) is sectional drawing of the other structural example of a strain sensor, (B) is the front view, (C) is the perspective view. It is sectional drawing which shows the state which attached the distortion sensor of FIG. 5 to the wheel bearing apparatus. It is a graph which shows the relationship between the distance from the bending corner | angular part of the distortion generation member in the distortion sensor of FIG. 5, and the magnitude | size of distortion. (A) is sectional drawing of the further another structural example of a strain sensor, (B) is the front view, (C) is the perspective view. It is a block diagram of one structural example of a processing circuit. It is a circuit block diagram which connected the amplifier circuit to the distortion sensor. It is a circuit block diagram which connected the amplifier circuit and the offset adjustment circuit to the distortion sensor. It is a graph which shows the relationship between the output voltage of a distortion sensor, and a mounting bolt clamping force. It is a block diagram of the other structural example of a processing circuit.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Outer member 2 ... Inner member 3, 4 ... Rolling surface 5 ... Rolling body 21 ... Strain sensor 22 ... Strain generating member 23 ... Strain measuring sensor element 40 ... Processing circuit 42 ... Offset adjustment circuit VR1, VR2 ... Variable resistor

Claims (4)

An outer member having a double row rolling surface formed on the inner periphery, an inner member having a rolling surface opposite to each rolling surface on the outer periphery, and a double row interposed between the rolling surfaces of each row In a wheel bearing device that includes a rolling element having a rolling surface, and rotatably supports the wheel with respect to the vehicle body,
A strain generating member including a strain generating member fixed to a fixed side member of the outer member and the inner member, a strain measuring sensor element attached to the strain generating member, and the sensor element of the strain sensor And a processing circuit for processing the distortion signal output from
This processing circuit has an offset adjusting means for adjusting an offset of the output of the sensor element, and is equipped with a sensor-equipped wheel bearing device.   The sensor-equipped wheel bearing device according to claim 1, wherein the offset adjusting unit is one of a variable resistor, a laser trimming resistor element, or a microcomputer having a setting value storage function for offset adjustment.   The sensor-equipped wheel bearing device according to claim 1 or 2, wherein the fixed side member is an outer member, and the strain generating member is attached to the outer member. 4. The vehicle body attachment force detection means for detecting the attachment force of the fixed side member to the vehicle body based on the output of the sensor, and whether or not the attachment force detected by the vehicle body attachment force detection means is within a set range. A bearing device for a wheel with a sensor provided with an attachment abnormality determining means for determining whether or not it is out of a set range and outputting an alarm signal.

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