JP5908243B2 - Bearing device for wheels with sensor - Google Patents

Description

  The present invention relates to a sensor-equipped wheel bearing device including a load sensor that detects a load applied to a bearing portion of a wheel.

  As a technology for detecting the load applied to each wheel of an automobile, a sensor-equipped wheel bearing has been proposed in which a strain gauge is attached to the outer ring outer diameter surface of the wheel bearing and the load is detected from the distortion of the outer ring outer diameter surface. (For example, Patent Document 1). In addition, a sensor-equipped wheel bearing that detects a load input from a road surface is mounted with a displacement detection type using an encoder as a load sensor (Patent Document 2). In addition, a sensor-equipped wheel bearing that compensates for the influence of the braking force using the pressure of the brake cylinder has been proposed (Patent Document 3). Furthermore, in order to compensate for the influence of the braking force, a sensor-equipped wheel bearing provided with a sensor for detecting the braking force acting on the caliper is proposed in addition to the load sensor (Patent Documents 4 and 5). Although it does not compensate for the effect of braking force, multiple sensor units are provided on the bearing fixed ring as strain detection sensors, and the difference between the amplitudes of the output signals of the sensor units arranged opposite to each other is obtained, and calculation is performed based on these values. There has also been proposed a wheel bearing with a sensor in which the input load is estimated by dividing (Patent Document 6).

Special table 2003-530565 gazette JP 2007-212389 A JP 2006-308465 A JP 2008-268201 A JP 2002-98138 A JP 2010-242902 A

  As shown in paragraphs [0013] to [0014] of Patent Document 4, in a configuration in which a sensor is provided on a bearing to detect an input load (road reaction force) from a road surface, a brake is applied during mechanical braking operation. Since the braking force is superimposed on the input load through the rotor, only the road surface reaction force during braking cannot be detected.

  As measures for solving this problem, Patent Documents 3 to 5 propose that a sensor for detecting the braking force is separately installed. In this case, however, the system configuration becomes complicated due to an increase in the number of sensors, wiring New problems such as increase, cost increase, and weight increase occur.

  Further, as proposed in Patent Document 3, it is possible to estimate the brake force by detecting the brake oil pressure. However, in this method, since the correspondence between the oil pressure and the brake force is not constant, it is detected by a bearing. It is difficult to accurately separate the braking force contained in the load from the load, and there is a problem in improving the load detection accuracy.

  The object of the present invention is to correct the load detected at the bearing portion from being affected by a predetermined situation of the vehicle, such as during braking, so that an accurate load can be obtained even if the situation of the vehicle is in a predetermined situation such as during braking. It is providing the wheel bearing apparatus with a sensor which can detect this.

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 opposed to the rolling surface formed on the outer periphery, and both A wheel bearing having a double row rolling element interposed between facing rolling surfaces of the member and rotatably supporting the wheel with respect to the vehicle body; and one or more sensors for detecting a load applied to the bearing; Signal processing means for processing a signal output from each sensor to generate a signal vector; and load calculation processing means for calculating a load applied to the wheel from the signal vector, wherein the load calculation processing means includes: It has a function of determining the presence or absence of a predetermined situation of the vehicle that affects the calculation result and performing two types of calculation processing corresponding to the presence or absence. In the present invention, the presence / absence of the predetermined situation of the vehicle determined by the load calculation processing means is ON / OFF of the brake. That the load processing means has a function of performing two types of processing corresponding to the brake ON · OFF, and the two kinds of arithmetic processing previously performed at the same time, the previous SL load processing means, or the by means of using the output of the load calculating processing means, one of the two previously arithmetic processed result of operation selected in accordance with the brake oN · OFF.

  According to this configuration, the load calculation processing means for calculating the load applied to the wheel determines the presence or absence of a predetermined condition of the vehicle that affects the load calculation result, and performs a function of performing two types of calculation processing corresponding to the presence or absence. I have it. Therefore, it is possible to correct the detected load at the bearing portion from being affected by a predetermined situation of the vehicle such as during a braking operation, and to detect an accurate load even if the situation of the vehicle is in a predetermined situation such as during braking.

  In this invention, the brake ON / OFF information determined by the load calculation processing means may be input from outside the load calculation processing means. That is, information from the vehicle, for example, information from an ECU (electric control unit) that performs overall control of the vehicle may be input to the load calculation processing means.

  In the present invention, the load calculation processing means may output both of two types of calculation processing results corresponding to brake ON / OFF. Which of the two types of output arithmetic processing results is to be used may be determined by the ECU on the vehicle side.

In the present invention, the load calculation processing means may calculate a load Fx acting at least in the front-rear direction. In this case, the load calculation processing means may determine ON / OFF of the brake using a load Fx acting in the front-rear direction as a result of the calculation processing. For example, a configuration may be adopted in which an appropriate threshold value is set and determined for the calculation result of the load Fx in the front-rear direction when the brake is OFF.
In the case of this configuration, there is no need to input brake ON / OFF information from outside the load calculation processing means.

In the present invention, the wheel load calculated by the load calculation processing means is a load applied to the driving wheel, and when the load calculation processing means determines that the brake is ON, information on the driving force applied by the vehicle is the vehicle. The load calculation processing means may be provided from the side and the load calculation processing means corrects the calculation processing result based on the information.
When applied to drive wheels, if drive torque is input from the drive shaft during braking operation, an error proportional to the magnitude is generated. Therefore, as information on the drive force applied by the vehicle, It is desirable to correct using the drive torque information.

  Further, in the present invention, the wheel load calculated by the load calculation processing means is a load applied to the driving wheel, and when the brake is ON, the load calculation processing means is based on the information of the driving force applied by the vehicle. The calculation processing result may be corrected by the vehicle-side ECU, and calculation parameters necessary for the correction may be read from the load calculation processing means and given to the ECU.

  In the present invention, three or more sensors for detecting the load applied to the wheel bearing are provided, and the load calculation processing means determines the vertical load Fz acting on the wheel bearing from the output signals of the three or more sensors. The longitudinal load Fx and the axial load Fy may be calculated.

In the present invention, in the calculation processing of the load calculation processing means, a load calculation coefficient matrix corresponding to brake ON and a load calculation coefficient matrix corresponding to brake OFF are used. The load calculation coefficient matrix corresponding to OFF may be calculated by conversion using a predetermined conversion formula.
In the brake-on state, the load value detected by the bearing (calculated by the brake-off state calculation method) is superimposed with interference components depending on conditions such as the brake caliper mounting position. A load estimation coefficient (load calculation coefficient) prepared in advance is used. The magnitude of the interference component caused by the brake is mechanically estimated from the caliper mounting position, and is calculated by converting the load calculation coefficient obtained in the brake OFF state. Since this conversion operation includes caliper position estimation errors, it is desirable to adjust the comparison with experimental data to improve the accuracy of the load calculation coefficient.

  In the present invention, the sensor that detects a load applied to the wheel bearing may detect a relative displacement between the outer member and the inner member.

  In the present invention, the sensor that detects a load applied to the wheel bearing may detect a distortion of a stationary member of the outer member and the inner member.

  In the present invention, the signal processing means may calculate an average value and an amplitude value from the output signal of the sensor, and generate a signal vector from these values.

  In the present invention, the sensor is a sensor unit provided on an outer diameter surface of a fixed side member of the outer member and the inner member, and the sensor unit contacts an outer diameter surface of the fixed side member. It is also possible to have a strain generating member that is fixed in place and one or more strain detecting elements that are attached to the strain generating member and detect the strain of the strain generating member.

In this invention, the sensor unit is positioned at 90 degrees in the circumferential direction on the upper surface portion, the lower surface portion, the right surface portion, and the left surface portion of the outer diameter surface of the fixed side member that is in the vertical position and the horizontal position with respect to the tire ground contact surface. You may distribute four equally by phase difference.
By arranging the four sensor units in this way, it is possible to estimate the vertical load Fz, the longitudinal load Fx, and the axial load Fy acting on the wheel bearing.

  The sensor unit has a strain generating member having three or more contact fixing portions fixed in contact with the outer diameter surface of the fixed side member, and is attached to the strain generating member to detect the strain of the strain generating member. It is also possible to have two or more strain detection elements.

In this sensor unit, the strain detection elements are provided adjacent to each other between the adjacent first and second contact fixing portions of the strain generating member and between the adjacent second and third contact fixing portions. You may set the space | interval of the said contact fixing | fixed part, or the space | interval of the said adjacent strain detection element to {n + 1/2 (n: integer)} times the arrangement pitch of rolling elements.
In the case of this configuration, the signals of the two strain detection elements have a phase difference of about 180 degrees, and the average value that is the sum of these signals is a value obtained by canceling the fluctuation component due to the rolling element passage. Also, the amplitude value, which is the difference between the signals of the two strain detection elements, is an accurate value that more reliably eliminates the effects of temperature and the effects of slipping on the knuckle / flange surface.

  In this case, the signal processing means may generate a signal vector using the sum of output signals of adjacent strain detection elements in the sensor unit as an average value.

In the wheel bearing device with sensor according to the present invention, the sensor, the signal processing means, and the load calculation processing means may be mounted on the wheel bearing.
The signal processing means and the load calculation processing means may be provided as a load calculation processing unit or the like or as a part of the main ECU in a vehicle in which the wheel bearing is installed apart from the wheel bearing. By mounting on the wheel bearing, the ECU may have a general configuration. Also in the case of mounting on a wheel bearing, if the signal processing means and the load calculation processing means are integrated as a load calculation processing unit, the mounting operation on the wheel bearing can be facilitated and can be installed compactly.

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 opposed to the rolling surface formed on the outer periphery, and both A wheel bearing having a double row rolling element interposed between facing rolling surfaces of the member and rotatably supporting the wheel with respect to the vehicle body; and one or more sensors for detecting a load applied to the bearing; Signal processing means for processing a signal output from each sensor to generate a signal vector; and load calculation processing means for calculating a load applied to the wheel from the signal vector; has a function of performing two types of processing corresponding to OFF, and the two kinds of arithmetic processing previously performed at the same time, the previous SL load processing means, or by means of using the output of the load calculating processing means, Brake ON / OFF Flip and for selecting either one of the two already operational treated calculation result, the detection load at bearing portion corrects the affected during braking operation, the status of the vehicle is in the braking Accurate load can be detected even in situations.

It is a figure showing combining the sectional view of the bearing of the bearing device for wheels with a sensor concerning one embodiment of this invention, and the block diagram of the conceptual composition of the detection system. It is the front view which looked at the outward member of the bearing from the outboard side. It is an enlarged plan view of a sensor unit in the sensor-equipped wheel bearing device. FIG. 4 is a cross-sectional view taken along arrow IV-IV in FIG. 3. It is sectional drawing which shows the other example of installation of a sensor unit. It is explanatory drawing of the influence of a rolling-element position with respect to the output signal of a sensor unit. It is explanatory drawing of the influence of the brake force on a detected load. It is a block diagram which shows the other structural example of a load calculation processing unit. It is a block diagram which shows the further another structural example of a load calculation processing unit. It is a block diagram which shows the further another structural example of a load calculation processing unit. It is a block diagram which shows the further another structural example of a load calculation processing unit. (A) is a graph showing the relationship between the sensor output signal amplitude and the axial load at the upper surface of the outer member outer diameter surface, and (B) is the sensor output signal amplitude and the axial load at the lower surface of the outer diameter surface. It is a graph which shows the relationship.

  An embodiment of the present invention will be described with reference to FIGS. This embodiment is a third generation type inner ring rotation type, and is applied to a wheel bearing 100 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 wheel bearing 100 in this sensor-equipped wheel bearing device includes, as shown in a cross-sectional view in FIG. 1, an outer member 1 in which a double row rolling surface 3 is formed on the inner periphery, and each rolling surface 3. It is comprised by the inner member 2 which formed the rolling surface 4 which opposes in an outer periphery, and the double row rolling element 5 interposed between the rolling surfaces 3 and 4 of these outer member 1 and the inner member 2. As shown in FIG. The wheel bearing 100 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 have an arc shape in cross section, and are formed so that the ball contact angle is aligned with the back surface. Both ends of the bearing space between the outer member 1 and the inner member 2 are sealed by a pair of seals 7 and 8, respectively.

The outer member 1 is a fixed side member, and has a vehicle body mounting flange 1a attached to a knuckle 16 in a 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 screw holes 14 for attaching a knuckle at a plurality of locations in the circumferential direction, and knuckle bolts (not shown) inserted into the bolt insertion holes 17 of the knuckle 16 from the inboard side are screwed into the screw holes 14. Thus, the vehicle body mounting flange 1a is attached to the knuckle 16.
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 braking component (not shown) protrudes toward the outboard side.

  FIG. 2 shows a front view of the outer member 1 of the wheel bearing 100 as viewed from the outboard side. 1 shows a cross-sectional view taken along the line II in FIG. As shown in FIG. 2, the vehicle body mounting flange 1 a is a projecting piece 1 aa in which a circumferential portion provided with each screw hole 14 protrudes to the outer diameter side from the other portion.

  Four sensor units 20 that are load detection sensors are provided on the outer diameter surface of the outer member 1 that is a stationary member. Here, these sensor units 20 are provided on the upper surface portion, the lower surface portion, the right surface portion, and the left surface portion of the outer diameter surface of the outer member 1 that is in the vertical position and the front-rear position with respect to the tire ground contact surface.

  The strain detection element 22 of each sensor unit 20 is connected to the load calculation processing unit 30 of FIG. The load calculation processing unit 30 includes signal processing means 31 that processes the output signal of each sensor unit 20 to generate a signal vector, and load calculation processing means 32 that calculates a load applied to the wheel from the signal vector. The signal processing means 31 and the load calculation processing means 32 do not necessarily have to be integrated as the load calculation processing unit 30, and may be provided separately from each other. Further, the signal processing means 31, the load calculation processing means 32, and the load calculation processing unit 30 may be mounted on the wheel bearing 100, and apart from the wheel bearing 100, in the vicinity of the main ECU. Or the like, or as a subordinate control unit of the overall control unit of the ECU.

  The load calculation processing means 32 has a function of determining the presence or absence of a predetermined situation of the vehicle that affects the calculation result of the load and performing two types of calculation processing corresponding to the presence or absence. Here, the load calculation processing means 32 determines whether the brake is ON / OFF as the presence or absence of a predetermined situation of the vehicle that affects the load calculation result, and performs two types of calculation processing corresponding to the brake ON / OFF. In the example of FIG. 1, the brake ON / OFF information is input to the load calculation processing means 32 as information from an external vehicle, for example, as direct information from an ECU (electric control unit) or a brake. When the load calculation processing means 32 is provided as a part of the ECU, the information from the ECU is input to the load calculation processing means 32 from a portion that performs higher control over the load calculation processing means 32 in the ECU. It will be.

  As shown in Patent Document 4 and the like, when a wheel is provided with a mechanical brake and a sensor is provided on the bearing to detect an input load (road reaction force) from the road surface, the brake rotor is passed through during braking operation. Since the braking force is superimposed on the input load, only the road surface reaction force cannot be detected when the brake is on. At least the load component to be detected acts on the load component Fx acting in the front-rear direction and the load component Fz acting on the vertical direction, and the influence of the braking force is generated.

This principle will be described below with reference to FIG. In the brake rotor such as a brake disk, the position of the brake pad is set at an angle θ upward from the traveling direction and a radius RB, and the brake force FB is applied to the brake rotor. The wheel radius is RW, and the input torque Tdrive is applied from the driving force. At this time, assuming that the load components of the road surface reaction force received from the road surface are Fx and Fz, the loads Fxb and Fzb detected by the bearing are expressed by the following equations (1-1) and (1-2).
Fxb = Fx−FB · sin θ (1-1)
Fzb = Fz + FB · cos θ (1-2)
However,
Fx, Fz: Road reaction force (load acting on the tire from the road surface)
Fxb, Fzb: Bearing force (load acting on the bearing rotating wheel, including brake interference)
Here, assuming that the drive torque input from the drive shaft is Tdrive and the brake torque by the brake operation is FB · RB, the torque relational expression acting on the wheel is expressed as the following expression (2).
Fx · Rw = Tdrive -FB · RB (2)
From this relational expression, the braking force FB is expressed as the following expression (3).
FB = (Tdrive−Fx · Rw) / RB (3)

  That is, when a sensor is provided on the bearing to detect an input load (road surface reaction force) from the road surface, a load component proportional to the brake force FB is obtained as in equations (1-1) and (1-2). It is added to the desired road surface load and detected. Therefore, in order to correctly determine the load components Fx and Fz acting on the road surface, it is necessary to determine and correct the braking force, and a configuration as shown in the above-mentioned patent document has been proposed.

However, when a sensor for detecting the braking force is separately provided, not only the wiring and processing circuit increase, but also an increase in weight for adding a structure for providing a detection portion becomes an unfavorable state for the suspension part.
In each of the embodiments of the present invention described below, it is possible to accurately detect the road load even during the braking operation by minimizing the influence of the brake with the simplest possible configuration.

  In this embodiment, the sensor unit 20 shown in FIGS. 2 to 6 is used as a sensor for detecting a load in each direction on the wheel. As will be described in detail later, each sensor unit 20 is attached to the strain generating member 21 (FIG. 5) fixed to the outer member 1 by three contact fixing portions 21 a (FIG. 5) and the strain generating member 2. It consists of two strain detecting elements 22 (22A, 22B) for detecting the strain of the strain generating member 2. The signal processing means 31 in FIG. 1 performs an input load estimation calculation process using the added value, amplitude value, and the like of the signals of these two strain detection elements 22.

  The sensor for detecting the load is not limited to the one shown in FIGS. 2 to 6. For example, a displacement sensor (such as an eddy current sensor, a magnetic sensor, or a reluctance sensor) may be used as the outer member 1 and the inner member. It is installed on the fixed side member of the side member 2, the detection target is arranged on the rotating wheel, the relative displacement amount between the outer member 1 and the inner member 2 is obtained, and the relationship between the load and the displacement obtained in advance. Thus, the applied load may be obtained. Further, the sensor may not be a sensor that directly measures the displacement, but may be an indirect displacement measuring method as disclosed in Patent Document 2. That is, in the configuration of this embodiment, the force acting between the inner member 2 and the outer member 1 of the bearing is detected directly or indirectly by a sensor provided on the fixed side member, and the input load is calculated by calculation. It is applied to a load sensor of a method for estimating

  In order to calculate the loads Fx, Fy, Fz in the three directions X, Y, and Z, or the moment load in each direction, at least three or more pieces of sensor information (sensor output signals) were used. Arithmetic processing configuration is required. That is, a sensor signal vector S (= {S0, S1,..., Sn}) extracted by processing and signal processing a plurality of sensor signals as necessary is generated, and load estimation calculation processing is executed using this. Thus, the load calculation processing unit 30 for obtaining the input load F (= {Fx, Fy, Fz,...}) Is provided.

  In the load detecting means having such a configuration, the load estimation is performed by determining the coefficient M and the offset Mo by numerical analysis or experiment so that the relational expression F = M · S + Mo is satisfied within the range where the linear approximation is established. Arithmetic processing becomes possible.

  Here, when the brake provided on the wheel is operating as described above, the influence of the brake is superimposed on the sensor signal detected by the bearing, and as described above, it differs from the road surface load to be detected originally. There arises a problem that a value is output as an operation result. Therefore, the load calculation formula obtained as described above cannot calculate an accurate estimated load when the brake is operating.

  Therefore, in this embodiment, in addition to the normal calculation processing method determined in the brake OFF state, a load calculation processing function for the brake ON state is mounted, and the configuration is switched from the normal load calculation processing method depending on the brake state. .

  In the embodiment of FIG. 1, in the load calculation processing unit 30, the brake state is input from the vehicle as a brake ON / OFF signal to the load calculation processing means 32 as described above, thereby switching the load calculation processing. That is, even in the brake ON state, a calculation method that takes into account the influence of the brake superimposed on the sensor signal is applied, so that a desired road load value is accurately calculated.

  The load calculation processing means 32 calculates the load Fx in the front-rear direction, the load Fy in the axial direction, the load Fz in the vertical direction, or the moment load in each direction. For these calculations, at least three or more are calculated. The calculation process using the sensor information is required. That is, in the signal processing stage 31, a sensor signal vector S (= {S0, S1,..., Sn}) extracted by processing and signal processing the input sensor output signal as necessary is generated. Using this, the load calculation processing means 32 executes a load calculation process to obtain an applied load F (= {Fx, Fy, Fz,...}). The sensor signal vector S mentioned here is an average value, an amplitude value, or the like generated by the signal processing unit 31 corresponding to each sensor unit 20 described above.

  In such a calculation configuration, in order to enable calculation processing by the load calculation processing means 32, the load calculation processing means 32 uses a relational expression of F = M · S + Mo as an arithmetic expression, and a range in which linear approximation is established. The coefficient M and the offset Mo are determined by numerical analysis and experiment so as to satisfy this relational expression.

  As described above, when the brake provided on the wheel is operating, the influence of the brake is superimposed on the sensor signal detected by the bearing, and the load calculation processing means 32 has a value different from the road surface load to be detected originally. Will be output. Therefore, if the above-described arithmetic expression is employed as it is, an accurate estimated load cannot be calculated when the brake is operating.

Therefore, in this embodiment, in the load calculation processing means 32, in addition to the normal calculation formula determined in the brake OFF state, a calculation formula for the brake ON state is prepared, and the calculation is performed for both cases of the brake ON / OFF. Processing is performed at the same time, and which calculation result is output is selected in accordance with the input brake state signal. In the reference proposal example, the two types of arithmetic expressions are switched and used in accordance with brake ON / OFF. As described above, the information on the brake state is input as a brake ON / OFF signal from the outside vehicle side, and the arithmetic expression for the arithmetic processing is thereby switched. That is, in the brake ON state, the processing considering the influence component of the brake to be superimposed on the sensor output signal is applied, ing as desired road load value is calculated correctly.

  FIG. 8 shows another configuration example of the load calculation processing unit 30. In this configuration example, brake information is not input from the vehicle side. In this case, the load Fx in the front-rear direction, which is the calculation result of the load calculation processing means 32, is compared with a preset threshold value using the comparator 33, and the brake state is determined from the comparison result. Yes. In this case, the load calculation processing means 32 simultaneously performs load calculation processing for both cases of brake ON / OFF, and the obtained value of the load Fx in the front-rear direction (either brake ON or brake OFF, or Both values) may be used to determine whether the vehicle is in a braking state, and an appropriate calculation result may be selected and output. Note that, when the determination is made using both values, the combination of both values results in an effect of improving the accuracy of the determination. With such a configuration, even in a situation where brake information is not provided from the vehicle side, it is possible to determine the brake state and calculate an accurate load estimated value.

  FIG. 9 shows still another configuration example of the load calculation processing unit 30. In this configuration example, the load calculation processing means 32 performs two types of load calculation, brake ON and brake OFF, and determines which calculation result to use on the vehicle side (for example, ECU) using the signal. Like to do.

An arithmetic expression in the brake-on state can be prepared based on an arithmetic expression obtained in the brake-off state. A method for deriving the arithmetic expression will be described below with reference to FIG.
From the above equation (3) and equations (1-1) and (1-2), the road surface load to be detected is as follows.
Fx = Fxb / (1 + α · sin θ) + (Tdrive / RB) · sin θ / (1 + α · sin θ) (4-1)
Fz = Fzb + Fxb. [Alpha] .cos [theta] / (1+ [alpha] .sin [theta])-(Tdrive / RB). [Alpha] .cos [theta] / (1+ [alpha] .sin [theta]) (4-2)
Where α = Rw / RB: radius ratio where Fdrive = Tdrive / RB
A = 1 / (1 + α · sin θ)
B = A · sin θ
C = A ・ α ・ cos θ
Then, equations (4-1) and (4-2) are as follows.
Fx = A · Fxb + B · Fdrive (5-1)
Fz = Fzb + C, Fxb-C, Fdrive (5-2)
Assume that the sensor load vector Fxb and Fzb can be calculated as follows by using the sensor signal vector S as an input in the brake OFF state and using the calculation coefficient matrix M and the offset Mo.
Fxb = Mx · S + Mox (6-1)
Fzb = Mz S + Moz (6-2)
Then, the arithmetic expressions (5-1) and (5-2) for brake ON are
Fx = A / Mx / S + A / Mox + B / Fdrive = Mx '/ S + Mox' + B / Fdrive (7-1)
Fz = (Mz + C.Mx) .S + (Moz + C.Mox) -C.Fdrive
= Mz '・ S + Moz'-C ・ Fdrive (7-2)
It becomes.

When Fdrive = 0 can be approximated, equations (7-1) and (7-2) are
Fx = A.Mx.S + A.Mox = Mx'.S + Mox '(8-1)
Fz = (Mz + C.Mx) .S + (Moz + C.Mox) = Mz'.S + Moz '
...... (8-2)
Thus, the calculation coefficient matrix M in the expressions (6-1) and (6-2) is represented by M ′.
The calculation coefficient matrix M ′ in the brake ON state can be calculated by the following conversion formula using the calculation coefficient matrix M in the brake OFF state.
Mx '= A · Mx (9-1)
Mox '= A ・ Mox (9-2)
Mz '= Mz + C · Mx (9-3)
Moz '= Moz + C · Mox (9-4)

  Here, the calculation coefficient matrix M is determined so that the load calculation process in the brake OFF state can be performed by the equations (6-1) and (6-2). That is, the relationship between the sensor signal and the detected load is obtained in advance by numerical analysis or measurement, and at least in the range where the linear relationship is established, the estimated load is calculated using equations (6-1) and (6-2). It can be calculated. For nonlinear characteristics, a method of approximating the calculation region by dividing it into several linear ranges may be adopted.

  When the target wheel whose load is to be measured is a driven wheel, since there is no drive shaft, there is no drive force Fdrive due to drive torque (Fdrive = 0). Therefore, the calculation coefficient matrix is converted as in the equations (9-1) to (9-4), and the load calculation processing in the brake state is executed by the calculation equations (8-1) and (8-2) using the matrix. Just do it.

  On the other hand, when the target wheel is a drive wheel, there may be an input torque Tdrive from the drive shaft even during the braking operation. In this case, B · Fdrive and Eqs. (7-1) and (7-2) An error corresponding to the term of -C · Fdrive occurs. Such a condition corresponds to a case where the brake is operated while driving torque is being input from a driving source, or a case where a regenerative brake is operating in a powerful engine brake or an electric vehicle. In this case, the value of Fdrive = Tdrive / RB may be calculated from the state of the engine brake torque and the regenerative torque on the control ECU side of the vehicle, and the output value of the load sensor may be corrected using this value. FIG. 10 shows another configuration example of the load calculation processing unit 30 that can cope with such a case. That is, the load calculation processing unit 30 is configured such that the Fdrive value calculated on the vehicle side is input to the load calculation processing means 32 and correction calculation is performed by the load calculation processing means 32.

  FIG. 11 shows still another configuration example of the load calculation processing unit 30. In this configuration example, the correction calculation performed by the load calculation processing means 32 in the case of FIG. 10 is performed by the load value correction means 35 on the control ECU 34 side of the vehicle. Here, the parameters B and C necessary for the correction calculation are acquired from the load calculation processing means 32 and stored in the vehicle control ECU 34 side, and the load value correction for the load data in the brake ON state is performed as the load value. This is done by the correction means 35.

  Regarding parameters α and θ in the calculation formula performed with reference to FIG. 7, approximate values can be obtained from the position of the brake caliper. However, since an error actually occurs, in the brake ON state and the OFF state, It is desirable to verify that the calculation output is adjusted by experiment and to reduce the error.

The effects obtained by each embodiment of the present invention are summarized as follows.
-Since the load in the brake-on state can be accurately detected, brake control and vehicle attitude control can be performed using the detected load, and safety and comfort can be further improved.
-Since the load state during braking can be detected without providing a separate sensor, the load sensing function can be installed in a limited space around the suspension without increasing the weight, cost, and number of wires.
-Since there is no need to change the structure for installing the calipers, there is no need to manufacture bearings with special shapes depending on the installation position, such as the left and right sides of the vehicle.
-Since no additional sensors or structural changes are required, even when the caliper mounting position and structure are different, it is possible to respond by changing the load calculation coefficient. Moreover, since parts can be shared and simplified, manufacturing costs can be reduced and maintenance can be facilitated.

  Next, specific examples of the sensor unit 20 and the signal processing means 31 in FIG. 1 will be described. Each of these sensor units 20 provided at four locations in FIG. 2 is attached to the strain generating member 21 and the strain generating member 21 as shown in FIGS. 3 and 4 in an enlarged plan view and an enlarged sectional view. It consists of two strain detecting elements 22 for detecting the strain of the strain generating member 21. The strain generating member 21 is made of an elastically deformable metal such as a steel material, and is made of a thin plate material of 2 mm or less. The strain generating member 21 has three contact fixing portions 21 a that are contact-fixed to the outer diameter surface of the outer member 1 via the spacers 23. The three contact fixing portions 21 a are arranged in a line in the longitudinal direction of the strain generating member 21. In FIG. 4, one strain detection element 22A of the two strain detection elements 22 is disposed between the contact fixing portion 21a at the left end and the contact fixing portion 21a at the center, and the contact fixing portion 21a at the center and the contact at the right end. Another strain detection element 22B is arranged between the fixed portion 21a. As shown in FIG. 3, notch portions 21 b are formed at two positions corresponding to the placement portions of the strain detection elements 22 </ b> A and 22 </ b> B on both side portions of the strain generating member 21. The corner of the notch 21b has an arcuate cross section. The strain detection element 22 detects a circumferential strain around the notch 21b. Note that the strain generating member 21 is plastically deformed even in a state in which an assumed maximum force is applied as an external force acting on the outer member 1 that is a fixed member or an acting force acting between the tire and the road surface. It is desirable not to do so. This is because when the plastic deformation occurs, the deformation of the outer member 1 is not transmitted to the sensor unit 20 and affects the measurement of strain. The assumed maximum force is, for example, the maximum force within a range in which the normal functioning of the wheel bearing 100 is restored when the force is removed without the wheel bearing 100 being damaged. It is.

  In the sensor unit 20, the three contact fixing portions 21a of the strain generating member 21 are at the same dimension in the axial direction of the outer member 1, and the contact fixing portions 21a are separated from each other in the circumferential direction. These contact fixing portions 21a are fixed to the outer diameter surface of the outer member 1 by bolts 24 via spacers 23, respectively. Each bolt 24 is inserted into a bolt insertion hole 26 of the spacer 23 from a bolt insertion hole 25 penetrating in the radial direction provided in the contact fixing portion 21 a, and a screw hole 27 provided in the outer peripheral portion of the outer member 1. Screwed on. In this way, by fixing the contact fixing portion 21a to the outer diameter surface of the outer member 1 via the spacer 23, each portion having the notch portion 21a in the strain generating member 21 having a thin plate shape is changed to the outer member 1. It becomes a state away from the outer diameter surface of this, and distortion deformation around the notch 21b becomes easy.

  As the axial position where the contact fixing portion 21a is disposed, an axial position that is the periphery of the rolling surface 3 of the outboard side row of the outer member 1 is selected here. Here, the periphery of the rolling surface 3 of the outboard side row is a range from the intermediate position of the rolling surface 3 of the inboard side row and the outboard side row to the formation portion of the rolling surface 3 of the outboard side row. It is. In order to stably fix the sensor unit 20 to the outer diameter surface of the outer member 1, a flat portion 1 b is formed at a location where the spacer 23 is contacted and fixed on the outer diameter surface of the outer member 1.

  In addition, as shown in a cross-sectional view in FIG. 5, grooves 1 c are provided at the three intermediate portions where the three contact fixing portions 21 a of the strain generating member 21 are fixed on the outer diameter surface of the outer member 1. Thus, the spacer 23 may be omitted, and the portions where the notches 21b of the strain generating member 21 are located may be separated from the outer diameter surface of the outer member 1.

  As the strain detection element 22, various elements can be used. For example, the strain detection element 22 can be formed of a metal foil strain gauge. In that case, the distortion generating member 21 is usually fixed by adhesion. Further, the strain detecting element 22 can be formed on the strain generating member 21 with a thick film resistor.

  In this sensor-equipped wheel bearing device, in the signal processing means 31 of the load calculation processing unit 30, as an output signal of each sensor unit 20, the average value and amplitude of the signals of the two strain detection elements 22A and 22B in the sensor unit 20 are obtained. Extract values etc. The average value in this case is the sum of the signals of the two strain detection elements 22A and 22B. The amplitude value in this case is an amplitude value calculated using the difference value between the signals of the two strain detection elements 22A and 22B.

  Since the sensor unit 20 is provided at an axial position around the rolling surface 3 in the outboard side row of the outer member 1, the signals a and b of the strain detection elements 22A and 22B are detected as shown in FIG. It is affected by the rolling elements 5 passing near the installation part of the unit 20. Even when the bearing is stopped, the signals a and b of the strain detection elements 22 </ b> A and 22 </ b> B are affected by the position of the rolling element 5. That is, when the rolling element 5 passes the position closest to the strain detection elements 22A and 22B in the sensor unit 20 (or when the rolling element 5 is at that position), the signals a and b of the strain detection elements 22A and 22B are It becomes the maximum value and decreases as the rolling element 5 moves away from the position as shown in FIGS. 6A and 6B (or when the rolling element 5 is at a position away from the position). When the bearing rotates, the rolling elements 5 sequentially pass through the vicinity of the installation portion of the sensor unit 20 at a predetermined arrangement pitch P. Therefore, the signals a and b of the strain detection elements 22A and 22B cycle the arrangement pitch P of the transfer body 5. As shown by a solid line in FIG. 6C, the waveform is close to a sine wave that periodically changes. Further, the signals a and b of the strain detection elements 22A and 22B are affected by temperature and hysteresis due to slippage between the surfaces of the knuckle 16 and the vehicle body mounting flange 1a (FIG. 1). Here, in the signal processing means 31, the sum of the signals a and b of the two strain detection elements 22A and 22B as described above is used as an average value, and the difference between the signals a and b of the two strain detection elements 22A and 22B. Is used as an output signal of the sensor unit 20. As a result, the average value is a value obtained by canceling the fluctuation component due to the passage of the rolling elements 5. The amplitude value is a value that cancels out the influence of temperature appearing in the signals a and b of the two strain detection elements 22A and 22B and the influence of slippage between the knuckle and flange surfaces. Therefore, by using the average value and the amplitude value as an output signal of the sensor unit 20 and using this as a variable in the calculation of the load calculation processing means 32 in the next stage, the load acting on the wheel bearing 100 and the tire ground contact surface is obtained. Calculation and estimation can be performed more accurately.

  In FIG. 6, among the three contact fixing portions 21a arranged in the circumferential direction of the outer diameter surface of the outer member 1 which is a fixed side member, the interval between the two contact fixing portions 21a located at both ends of the array is changed. It is set to be the same as the arrangement pitch P of the moving bodies 5. In this case, the circumferential interval between the two strain detection elements 22A and 22B respectively disposed at the intermediate positions of the adjacent contact fixing portions 21a is approximately ½ of the arrangement pitch P of the rolling elements 5. Become. As a result, the signals a and b of the two strain detection elements 22A and 22B have a phase difference of about 180 degrees, and the average value obtained as the addition value is obtained by canceling the fluctuation component due to the passage of the rolling element 5. It becomes. The amplitude value obtained using the difference value is a value that offsets the influence of temperature and the influence of slippage between the knuckle and the flange surface.

In FIG. 6, the interval between the contact fixing portions 21 a is set to be the same as the arrangement pitch P of the rolling elements 5, and one strain detection element 22 </ b> A, 22 </ b> B is disposed at an intermediate position between the adjacent contact fixing portions 21 a. Thus, the circumferential interval between the two strain detection elements 22A and 22B is set to be approximately ½ of the arrangement pitch P of the rolling elements 5. Alternatively, the circumferential interval between the two strain detection elements 22A and 22B may be directly set to ½ of the arrangement pitch P of the rolling elements 5.
In this case, the circumferential interval between the two strain detection elements 22A and 22B is {1/2 + n (n: integer)} times the arrangement pitch P of the rolling elements 5, or a value approximated to these values. Also good. Also in this case, the average value obtained as the added value of the signals a and b of both strain detection elements 22A and 22B is a value obtained by canceling the fluctuation component due to the passage of the rolling element 5, and the amplitude value obtained using the difference value is It is a value that offsets the effects of temperature and the effects of slippage between the knuckle and flange surfaces.

  In the calculation of the axial load Fy, among the plurality of sensor units 20, the amplitude values of the output signals of the two sensor units 20 that are arranged to face each other with a phase difference of 180 degrees in the circumferential direction of the outer member 1 are used. , The direction of the axial load Fy can be determined from the difference value. For example, as the two sensor units 20, the sensor units 20 arranged so as to face each other in the vertical direction can be selected. 12A shows an output signal of the sensor unit 20 arranged on the upper surface portion of the outer diameter surface of the outer member 1, and FIG. 12B is arranged on the lower surface portion of the outer diameter surface of the outer member 1. The output signal of the sensor unit 20 is shown. In these figures, the horizontal axis represents the axial load Fy, the vertical axis represents the strain amount of the outer member 1, that is, the output signal of the sensor unit 20, and the maximum value and minimum value are the maximum value and minimum value of the output signal. Represents. From these figures, when the axial load Fy is in the positive direction, the load of each rolling element 5 decreases at the upper surface of the outer diameter surface of the outer member 1 and increases at the lower surface of the outer diameter surface of the outer member 1. I understand that. On the other hand, when the axial load Fy is in the negative direction, the load of the individual rolling elements 5 increases at the upper surface portion of the outer member 1 and the lower surface of the outer member 1. It turns out that it becomes small in a part. Therefore, the difference value indicates the direction of the axial load Fy.

  Thus, according to the wheel bearing with sensor, one or more (here, four) sensor units 20 are provided as sensors for detecting the load applied to the wheel bearing 100, and the output signal of each sensor unit 20 is a signal. A signal vector S is generated by processing by the processing means 31, and a load applied to the wheel is calculated by the load calculation processing means 32 using the signal vector S, and the load calculation processing means 32 adds the load calculation result to the load calculation result. Since it has a function to determine the presence or absence of a predetermined situation of the affected vehicle (in this case, brake ON / OFF) and to perform two types of arithmetic processing corresponding to the presence or absence, the detected load at the bearing is braked It is possible to correct the influence of a predetermined situation of the vehicle such as during operation, and to detect an accurate load even if the situation of the vehicle is in a predetermined situation such as during braking.

  When a load acts between the tire of the wheel and the road surface, the load is also applied to the outer member 1 that is a fixed member of the wheel bearing 100, and deformation occurs. In this embodiment, since the three contact fixing portions 21a of the strain generating member 21 in the sensor unit 20 are fixed to the outer member 1, the strain of the outer member 1 is expanded and transmitted to the strain generating member 21. The distortion is easily detected by the strain detection elements 22A and 22B.

  Further, in this embodiment, four sensor units 20 are provided, and each sensor unit 20 is provided with an upper surface portion, a lower surface portion, and a right portion of the outer diameter surface of the outer member 1 that are in a vertical position and a horizontal position with respect to the tire ground contact surface. Since the surface portion and the left surface portion are equally arranged with a phase difference of 90 degrees in the circumferential direction, the vertical load Fz, the longitudinal load Fx, and the axial load Fy acting on the wheel bearing 100 can be estimated. .

  The sensor unit 20 used in this embodiment includes a strain generating member 21 fixed in contact with the outer diameter surface of the fixed side member, and a strain generating member 21 attached to the strain generating member 21. However, the strain generating member 21 may be provided with one strain detecting element. In this case, one strain detecting element of the strain detecting element 21 may be provided. The average value or amplitude value of the signal may be used as a variable for the load calculation.

In this embodiment, 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 20 is provided on the peripheral surface that is the inner periphery of the inner member.
In this embodiment, the case where the present invention is applied to the third generation type wheel bearing 100 has been described. However, the present invention is for the 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. The sensor-equipped wheel bearing device can also 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.

DESCRIPTION OF SYMBOLS 1 ... Outer member 2 ... Inner member 3, 4 ... Rolling surface 5 ... Rolling body 20 ... Sensor unit 21 ... Strain generating member 21a ... Contact fixing | fixed part 22, 22A, 22B ... Strain detection element 31 ... Signal processing means 32 ... Load calculation processing means 33 ... Comparator 34 ... Control ECU
35 ... Load value correcting means 100 ... Wheel bearing

Claims (19)

An outer member in which a double row rolling surface is formed on the inner periphery, an inner member in which a rolling surface facing the rolling surface is formed on the outer periphery, and an intermediate member between both members facing each other. A wheel bearing having a double row rolling element and rotatably supporting the wheel with respect to the vehicle body;
One or more sensors for detecting a load applied to the bearing, a signal processing unit for processing a signal output from each sensor to generate a signal vector, and a load calculation processing unit for calculating a load applied to the wheel from the signal vector And
The load processing means has a function of performing two types of processing corresponding to the brake ON · OFF, and the two kinds of arithmetic processing previously performed at the same time, the previous SL load processing means, or the load calculated by means of using the output of the processing means, the two already operational processed operation result one wheel support bearing assembly equipped sensor characterized by select in response to the brake oN · OFF.   The sensor-equipped wheel bearing device according to claim 1, wherein the load calculation processing means selects which calculation result of the two types of calculation processing is output according to brake ON / OFF.   3. The sensor-equipped wheel bearing device according to claim 1, wherein brake ON / OFF information determined by the load calculation processing means is input from outside the load calculation processing means.   2. The wheel bearing device with sensor according to claim 1, wherein the load calculation processing means outputs both of two types of calculation processing results corresponding to brake ON / OFF.   5. The sensor-equipped wheel bearing device according to claim 1, wherein the load calculation processing means calculates a load Fx acting at least in the front-rear direction.   6. The sensor-equipped wheel bearing device according to claim 5, wherein the load calculation processing means determines ON / OFF of the brake using a load Fx acting in the front-rear direction as a result of the calculation processing.   The vehicle according to any one of claims 1 to 6, wherein the load of the wheel calculated by the load calculation processing means is a load applied to the drive wheel and the load calculation processing means determines that the brake is ON. A sensor-equipped wheel bearing device in which information on the applied driving force is given to the load calculation processing means from the vehicle side, and the load calculation processing means corrects the calculation processing result based on the information.   7. The information on the driving force applied by the vehicle when the brake is ON, wherein the wheel load calculated by the load calculation processing means is a load applied to the driving wheel according to any one of claims 1 to 6. A sensor-equipped wheel bearing device in which the calculation processing result of the load calculation processing means is corrected by the ECU on the vehicle side, and calculation parameters necessary for the correction are read from the load calculation processing means and given to the ECU.   9. The method according to claim 1, wherein three or more sensors for detecting a load applied to the bearing are provided, and the load calculation processing means is configured to generate a wheel bearing from output signals of the three or more sensors. A sensor-equipped wheel bearing device that calculates a vertical load Fz, a longitudinal load Fx, and an axial load Fy acting on the vehicle.   The load calculation coefficient matrix corresponding to the brake ON and the load calculation coefficient matrix corresponding to the brake OFF are used in the calculation process of the load calculation processing means according to any one of claims 1 to 9, and the brake ON The load calculation coefficient matrix corresponding to is calculated by converting the load calculation coefficient matrix corresponding to brake OFF by a predetermined conversion formula.   11. The sensor-equipped wheel bearing device according to claim 1, wherein the sensor that detects a load applied to the bearing detects a relative displacement between the outer member and the inner member. .   11. The sensor-equipped wheel according to any one of claims 1 to 10, wherein the sensor that detects a load applied to the bearing detects distortion of a fixed-side member of the outer member and the inner member. Bearing device.   13. The sensor-equipped wheel bearing device according to claim 12, wherein the signal processing means calculates an average value and an amplitude value from an output signal of the sensor and generates a signal vector from these values.   14. The sensor according to claim 13, wherein the sensor is a sensor unit provided on an outer diameter surface of a fixed side member of the outer member and the inner member, and the sensor unit contacts an outer diameter surface of the fixed side member. A sensor-equipped wheel bearing device comprising: a strain generating member that is fixed in a fixed manner; and one or more strain detecting elements that are attached to the strain generating member and detect strain of the strain generating member.   15. The sensor unit according to claim 14, wherein the sensor unit has a circumferential direction of 90 degrees on an upper surface portion, a lower surface portion, a right surface portion, and a left surface portion of the outer diameter surface of the fixed side member that is in a vertical position and a horizontal position with respect to a tire ground contact surface. Bearing device for wheels with sensor that is equally distributed by four phase differences.   15. The strain generating member according to claim 14, wherein the sensor unit has three or more contact fixing portions fixed in contact with the outer diameter surface of the fixed side member, and the strain generating member is attached to the strain generating member. A bearing device for a wheel with a sensor having two or more strain detection elements for detecting strain of a member.   17. The strain detection element according to claim 16, wherein the strain detection element is provided between the adjacent first and second contact fixing portions of the strain generating member and between the adjacent second and third contact fixing portions. A sensor-equipped wheel bearing device in which an interval between the contact fixing portions or an interval between adjacent strain detection elements is set to {n + 1/2 (n: integer)} times the arrangement pitch of rolling elements.   18. The sensor-equipped wheel bearing device according to claim 17, wherein the signal processing means generates a signal vector by using a sum of output signals of adjacent strain detection elements in the sensor unit as an average value.   The wheel bearing with a sensor according to any one of claims 1 to 18, wherein the sensor, the signal processing means, and the load calculation processing means are mounted on the wheel bearing.

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