JP4931623B2 - Wheel bearing device with sensor - Google Patents

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, based on the detection result, the suspension and the like are controlled in advance, thereby controlling the posture 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 is such that 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.
・ Although load estimation is performed based on strain measurement using a strain generating member, there are temperature characteristics, individual differences in sensor elements, nonlinear characteristics, and changes in characteristics depending on the mounting state. And accurate load measurement is not possible.
Although correction can be performed by an electric control unit (ECU) on the vehicle body side that receives the output signal of the sensor element, it is cumbersome and inefficient to individually perform correction processing unique to each part.
・ It is necessary to secure the performance of a single bearing device with a sensor. To this end, it is necessary to eliminate individual differences in the sensor characteristics of the bearing on the vehicle body side that uses the output signal of the sensor element, or to add a compensation function to the bearing. is there.
・ It is also desirable to have a function to detect and judge changes in sensitivity characteristics and offsets due to environmental changes and aging changes during use, and to calibrate periodically.
-It is also desirable to have an interface that connects to an information communication network such as an automobile.

  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, 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 includes an amplifier circuit, an offset adjustment circuit, a storage unit, a correction unit, and an external interface, and the storage unit stores characteristics that are individual differences between the strain sensor and the bearing, The correction means is as described above. And corrects the output of the sensor element in accordance with the stored contents of the unit, the external interface is characterized in that the one capable of input to the storage unit.
According to this configuration, the processing circuit for processing the distortion signal output from the sensor element is provided, and since this processing circuit includes the amplification circuit, the offset adjustment circuit, the storage unit, and the correction unit, the load signal detected by the bearing is processed. Can be output in a properly calibrated state. Therefore, the load state of the bearing can be obtained easily and accurately on the vehicle body side using the signal.
In addition, since the storage means stores characteristics that are individual differences between the strain sensor and the bearing, and the correction means corrects the output of the sensor element in accordance with the stored contents of the storage means, the individual strain sensor and bearing The difference is compensated by the processing circuit. For this reason, when the sensor-equipped bearing device is incorporated on the vehicle body side, the output signal of the strain sensor can be used immediately, and calibration is unnecessary.
Since the processing circuit has an external interface, input of correction data to the storage means, correction of stored correction data, reading of ID information, and the like can be performed from the outside. It is also possible to detect an offset change due to secular change or impact load and correct it from the outside to maintain an accurate load detection capability.

The strain generating member before Kiyugami sensor has a contact fixing segments of the two locations relative to the stationary member, the flange surface first contact fixing portion of the contact fixing portion provided on said stationary member is secured to, the second contact fixing member is fixed to the peripheral surface of the stationary member. In the case of this configuration, the radial positions of the first and second contact fixing portions are different, and the distortion of the fixed side member is easily transferred and enlarged on the distortion generating member. Since this transferred and enlarged strain is measured by the sensor element, the strain of the fixed member can be detected with high sensitivity, and the load measurement accuracy is increased.

In the present invention, pre-Symbol processing circuit includes a linear correction circuit as compensation circuits, the offset adjusting circuit is one having an offset compensating function, said processing circuit, the amplifier circuit, the offset adjustment circuit, the storage means In addition to the correction means and the external interface, a signal output circuit and a control circuit for controlling any of these offset adjustment circuit, storage means, correction means, and signal output circuit may be included. When the control circuit is provided in this way, it is easy to improve the output accuracy of the processing circuit.

  In the present invention, the storage means stores a sensitivity correction value, a temperature correction value, and a bearing identification code of the strain sensor, and the processing circuit controls circuit operation according to the stored contents of the storage means. It may be. In the case of this configuration, sensitivity correction and temperature correction of the strain sensor can be performed, or input, update, management, etc. for this correction can be managed for each individual bearing using the identification code.

  In the present invention, there may be provided read / write means for reading / writing the storage contents of the storage means from the outside with respect to the processing circuit. Thus, when the reading / writing means for reading / writing from the outside is provided, reading / writing to the storage means can be easily performed.

  In the present invention, the read / write means may be a wireless communication means. In the case of this configuration, it is possible to reduce wiring and reduce the size. Since reading / writing with respect to the storage means is not always necessary, if the reading / writing means is a wireless communication means, reading / writing can be easily performed when necessary, and complication of a wiring system such as a harness can be avoided.

  In the present invention, the external interface may be of a type connectable to a vehicle body control communication bus of an automobile. In the case of this configuration, versatility is increased and easy connection 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 includes an amplifier circuit, an offset adjustment circuit, a storage unit, a correction unit, and an external interface, and the storage unit stores characteristics that are individual differences between the strain sensor and the bearing, The correction means is as described above. And corrects the output of the sensor element in accordance with the stored contents of the unit, the external interface, and one capable of input to the storage means, the strain generating member of the strain sensors, to the fixed side member It has two contact fixing parts, and among the contact fixing parts, the first contact fixing part is fixed to a flange surface provided on the fixing side member, and the second contact fixing member is a periphery of the fixing side member. order to be fixed to a surface, the load signal detected by the bearings is output in a state of being properly calibrated by the processing circuit. Therefore, the load state of the bearing can be obtained easily and accurately on the vehicle body side using the signal.

  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 in this wheel bearing device with a sensor is composed of an outer member 1 in which a double row rolling surface 3 is formed on the inner periphery, and an inner member 2 in which a rolling surface 4 facing each of the rolling surfaces 3 is formed. And the 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 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 a knuckle in a suspension device (not shown) of a 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. 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. In the case of the strain sensor 21, a temperature sensor element 24 is provided adjacent to the strain measuring sensor element 23.

  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 and the temperature sensor element 24 are 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 load expected for the wheel bearing is applied. 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 by pressing from a metal material such as a steel material. 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, the strain is measured. It is preferable that the amount of strain at the portion of the generating member 22 where the strain measuring sensor element 23 is attached 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.

  As the temperature sensor element 24 attached to the strain generating member 22 in FIG. 4, for example, a platinum resistance thermometer, a thermocouple, or a thermistor can be used. Furthermore, a sensor capable of detecting a temperature other than these can also be used.

  In the axle bearing provided with the strain sensor 21, the strain measuring sensor element 23 detects the strain of the strain generating member 22, and measures the load applied to the wheel by the strain. By the way, the temperature of the wheel bearing changes during use, and the change in temperature affects the strain of the strain generating member 22 or the operation of the sensor element 23 for strain measurement. Therefore, the temperature of the strain generating member 22 is detected by the temperature sensor element 24 arranged on the strain generating member 22, and the output of the strain measuring sensor element 23 is corrected by the detected temperature, whereby the strain measuring sensor element 23 is corrected. The influence of the temperature can be eliminated. Thereby, highly accurate load detection can be performed.

  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. Bolts 39 screwed into the provided bolt holes 37 and inserted from the bolt insertion holes 32 of the axial piece 22B into the bolt insertion holes 36 of the second contact fixing member 34 are provided on the outer peripheral surface of the outer member 1. The distortion generating member 22 is fastened to the outer member 1 by being screwed into the formed bolt 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 at a position 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, the portion of the strain generating member 22 that receives the strain in the radial piece 22 </ b> A (the portion close to the bent corner portion 22 </ b> C) has the same or different characteristics. Two strain measuring sensor elements 23 are arranged, and the strain measuring sensor elements 23 are not arranged in a portion not affected by the distortion (a portion far from the bent corner portion 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. for processing the output signal of the measurement sensor element 23 and a power / electrical component 28 for driving the strain measurement sensor element 23 are 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 sensor signal processing circuit to the outside. When the strain sensor 21 is provided with various sensor elements such as the above-described temperature sensor element 24 in addition to the strain measurement sensor element 23, the sensor signal processing circuit unit 25 has a circuit board 27 corresponding to each sensor element. The electrical / electronic component 28, the joint 29, the cable 30 and the like are provided (not shown).

  FIG. 9 is a block diagram showing a configuration 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 circuit of the strain sensor 21 and the amplifier circuit 41 that amplifies the output signal. The circuit of the strain sensor 21 in this case is of the configuration example shown in FIGS. 5 and 6, and includes two strain measurement sensor elements 23 (S 1) at positions where distortion is received, and positions where they are not affected by the distortion. These two strain measurement sensor elements 23 (S2) are bridge-connected. The amplifier circuit 41 is composed of an operational amplifier.
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. In the bridge connection detection circuit, a fixed resistor may be provided instead of providing the two strain measuring sensor elements 23 (S2) at positions not affected by the distortion. Basically, the load applied to the wheel bearing 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, the strain sensor 21 has manufacturing variations, and there are individual differences in offset, sensitivity, temperature characteristics, and the like. Furthermore, the sensitivity characteristic of the strain sensor 21 also changes depending on the state of attachment when the wheel bearing is attached to the vehicle body. The offset adjustment circuit 42 and various correction circuits 44 in the processing circuit 40 are circuits for correcting the individual differences described above.

  That is, the offset adjustment circuit 42 adjusts the initial offset of the strain sensor 21 and the offset due to fixing to the wheel bearing to normal values. The temperature sensor element 24 as shown in FIG. 4 may be provided in the strain sensor 21. In this case, the control circuit 47 automatically compensates the sensor offset based on the output of the temperature sensor element 24. it can.

  FIG. 11 shows a specific 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. The offset adjustment circuit 42 has an offset compensation function. That is, the input voltage e1 corresponding to the detection output of the temperature sensor element 24 is input from the control circuit 47 to the terminal T1, whereby temperature compensation of the offset value is performed, and the variable resistor VR1 is changed according to the condition of individual differences. , VR2 is changed by the control circuit 47 to compensate for individual differences in offset values.

  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 unit 43 is composed of, for example, a non-volatile memory, and stores parameters for correcting offset temperature characteristics, sensitivity, and nonlinearity. The control circuit 47 controls the correction processing of various correction circuits 44 based on these parameters.
For example, as shown in FIG. 12, since the output characteristic of the strain sensor 21 has a non-linear relationship with the load applied to the wheel, the characteristic data is tabulated and stored in the storage means 43, or the form of parameters of the approximate curve Is stored in the storage means 43. 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.

  FIG. 13 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. In other words, the output characteristics of the strain sensor 21 have individual differences between the bearing devices attached to each vehicle body. Therefore, the correction data stored in the storage means 43 reflects the state of attachment to the vehicle body. The storage means 43 may store a bearing identification code (ID).

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. Via the external interface 45, correction data stored in the storage means 43 can be corrected and ID information can be read from the outside. Further, for example, in the ECU or the like of external automobile, with a signal output for a certain period to result from the use state and the strain sensor 21 of the vehicle can be estimated and detection of sudden changes in offset due to over a year change or impact load. Furthermore, since the offset data stored in the storage means 43 can be corrected via the external interface 45 from an external ECU or the like based on the estimation / detection result, accurate load detection capability can be maintained. .

  The external interface 45 may be of a type that can be connected to a vehicle body control communication bus such as a CAN bus. In this case, versatility is enhanced and easy connection with the outside becomes possible.

  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.

As described above, in this sensor-equipped wheel bearing device, the strain generating member 22 fixed to the fixed member (here, the outer member) of the outer member 1 and the inner member 2, and the strain generating member 22 And a processing circuit 40 for processing a distortion signal output from the sensor element 23 of the strain sensor 21, and the processing circuit 40 includes an amplification circuit. 41, an offset adjustment circuit 42, a storage means 43, various correction circuits 44, and an external interface 45. The storage means 43 stores characteristics that are individual differences between the strain sensor 21 and the bearing, and the correction circuit 44. is intended to correct the output of the sensor element 23 in accordance with the stored contents of the storage means 43, the external interface 45, versus in the storage means 43 Having assumed that can be input Te, it is output in a state in which the load signal detected by the bearing is properly calibrated, at the vehicle body side utilizing signal can be obtained accurately and simply load condition of the bearing.

  Similarly, since the individual difference between the strain sensor 21 and the bearing is compensated, when the bearing device with the sensor is incorporated on the vehicle body side, the output signal of the strain sensor 21 can be used immediately, and calibration is not necessary. .

  Since the external interface 45 is provided, correction data stored in the storage unit 43 can be corrected and ID information can be read from the outside. Further, it is possible to detect an offset change due to a secular change or an impact load and correct it from the outside to maintain an accurate load detection capability.

  The sensor signal compensation calculation in the processing circuit 40 of FIG. 9 in the above embodiment may be executed by an external ECU or the like. In this case, since the correction data in the storage unit 43 is read from the outside, the correction process equivalent to the above-described case according to the characteristics of the individual differences between the strain sensor 21 and the bearing is executed by an external ECU or the like. There is no need to store individual parameters according to individual differences on the ECU side.

  In this way, when using an external ECU or the like, if a method of storing only the bearing ID information in the storage means 43 and referring to several types of characteristic tables prepared separately is employed, the capacity is reduced. Necessary functions can also be realized by the storage means 43.

  In the above embodiment, instead of using an ECU or the like, a read / write unit 49 such as a wireless communication unit (using RFID) that reads / writes data stored in the storage unit 43 from the outside to the processing circuit 40 is additionally provided. You may do it. In this case, wiring saving and miniaturization are possible. The read / write unit 49 may be provided as a part of the functional portion of the external interface 45.

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. 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. (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 the processing circuit in a sensor signal processing circuit unit. 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 of a strain sensor, and the load added to a wheel. It is a graph which shows the relationship between the output voltage of a strain sensor, and a mounting bolt clamping force.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Outer member 1a ... Flange 2 ... Inner member 3, 4 ... Rolling surface 5 ... Rolling element 21 ... Strain sensor 22 ... Strain generating member 22a ... 1st contact fixing part 22b ... 2nd contact fixing part 23 Strain measuring sensor elements 33 and 34 Contact fixing member 40 Processing circuit 41 Amplifying circuit 42 Offset adjustment circuit 43 Storage means 44 Correction circuit 45 External interface 46 Signal output circuit 47 Control circuit

Claims (6)

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
The processing circuit includes an amplification circuit, an offset adjustment circuit, a storage unit, a correction unit, and an external interface. The storage unit stores characteristics that are individual differences between the strain sensor and the bearing. The output of the sensor element is corrected according to the storage contents of the storage means, the external interface is capable of inputting to the storage means, and the strain generating member of the strain sensor is fixed to the fixed side member. And the first contact fixing portion is fixed to a flange surface provided on the fixed side member, and the second contact fixing member is formed on the fixed side member. sensor-equipped wheel support bearing assembly according to claim and this fixed to the peripheral surface. According to claim 1, pre-Symbol processing circuit includes a linear correction circuit as compensation circuits, the offset adjustment circuit are those having an offset compensating function, said processing circuit, the amplifier circuit, the offset adjusting circuit, a storage Sensor-equipped wheel bearing device having a signal output circuit and a control circuit for controlling any of these offset adjustment circuit, storage means, correction means, and signal output circuit in addition to the means, the correction means, and the external interface . 3. The storage device according to claim 1 , wherein the storage means stores a sensitivity correction value, a temperature correction value, and a bearing identification code of the strain sensor, and the processing circuit is a circuit according to the storage content of the storage means. A wheel bearing device with a sensor for controlling the operation. 4. The bearing device for a wheel with a sensor according to claim 3 , further comprising a reading / writing means for reading / writing the stored contents of the storage means from the outside with respect to the processing circuit. 5. The wheel bearing device with sensor according to claim 4 , wherein the read / write means is a wireless communication means. In any one of claims 1 to 5, wherein the external interface, the sensor equipped wheel support bearing assembly is of connectable format to the vehicle body control system communication bus of the vehicle.

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