JP2006003281A - Moment detection apparatus, tire generative force detection apparatus, and wheel abnormality detection apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a moment detection apparatus which detects a moment applied to a rotation axis of a rotating body, a tire generative force detection apparatus which detects a tire generative force generating between a tire and a road surface, and a wheel abnormality detection apparatus which prevents an accident such as tire separation. <P>SOLUTION: When an effective value ratio between wheel speed sensors 10, 12 is detected by a characteristic amount detection section 16 as a "characteristic amount", an average value of the detected characteristic amount per one rotation of a tire is calculated by a characteristic amount average value calculation section 18. A correction coefficient is derived by a correction coefficient derivation section 20 for each detected characteristic amount. A characteristic amount correction section 22 corrects the characteristic amount using the derived correction coefficient. A tire generative force detection section 24, on the basis of the prestored relationship between the characteristic amount and the tire generative force under a predetermined rotation speed, detects a tire generative force from the corrected characteristic amount. A correction coefficient fluctuations detection section 31 detects an amount of fluctuations from a reference correction coefficient for the derived correction coefficient. An abnormality detection section 32 detects a wheel abnormality from the detected amount of fluctuations. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a moment detection device, a tire generation force detection device, and a wheel abnormality detection device, and more specifically, a moment detection device that detects a moment applied to a rotation shaft that serves as a reference for rotation of a rotating body, and a tire. The present invention relates to a tire generation force detection device that detects a tire generation force generated between a road surface and a wheel abnormality detection device that detects that an abnormality has occurred in an element that constitutes a wheel.

  Conventionally, to detect the tire friction and detect the tire force such as longitudinal force, self-aligning torque, and lateral force generated in the tire in order to improve the preventive safety control performance of the vehicle, such as preventing the wheel from skidding. is doing.

  For example, Patent Document 1 includes a wheel having a tire mounted on the outer periphery of a wheel, and a vehicle body having a hub as a holding body that rotatably holds the wheel integrally by mounting the wheel coaxially. Disclosed is a tire action force detection device mounted on a vehicle equipped with a detector that detects a tire action force provided between a wheel and a holding body in a state of transmitting force between them. is doing.

On the other hand, various methods for detecting displacement without contact have been proposed based on electromagnetic principles such as electromagnetic induction. For example, in Patent Document 2, two types of coils surrounding the outer periphery of a cylindrical magnetic target fixed on the rotating body side are fixed on the stator side, one is an exciting coil, and the other is an induced voltage. A displacement sensor is disclosed that detects the position of two targets in the radial direction of the target by utilizing the fact that the mutual inductance of the two types of coils changes due to the displacement of the magnetic target as a detection coil.
JP 2003-14563 A JP 2001-165704 A

  However, in the tire acting force detection device disclosed in Patent Document 1, since it is necessary to configure the detector in a “state in which force is transmitted (contact state)”, the structure of the device is complicated. In addition, since the tire acting force is detected by “force transmission”, there is a problem that the detection accuracy is likely to be affected by vibrations from the road surface.

  Moreover, the displacement sensor of patent document 2 can be attached to the member displaced according to a tire generating force, and a tire generating force can also be calculated | required from the detected displacement amount. However, when the rotational axis of the target rotor is eccentric (axial eccentricity), or when there is an error in mounting the displacement sensor, the sensor signal has periodic fluctuations (swells) that depend on the rotational speed. appear. The main causes of shaft eccentricity are axle machining accuracy, axle mounting error, and the like. It is difficult to separate the fluctuation caused by the shaft eccentricity and the sensor mounting error from the fluctuation caused by the tire generating force, and there is a problem that the detection accuracy of the tire generating force is lowered due to the shaft eccentricity or the like.

  Similarly, when an abnormality occurs in the elements (hub, bearing, wheel, tire, etc.) constituting the wheel, such as a decrease in tire air pressure, the force applied to the bearing fluctuates. It is difficult to separate the fluctuation caused by the wheel abnormality from the fluctuation caused by the tire generating force, and there is a problem that the detection accuracy of the tire generating force is lowered.

  It is also necessary to detect the occurrence of wheel abnormalities and issue a warning to the driver.

  The present invention has been made to solve the above problems, and an object of the present invention is to detect a moment that can accurately detect the moment applied to the rotating shaft of the rotating body, regardless of the shaft eccentricity of the rotating body. To provide an apparatus.

  Another object of the present invention is to provide a tire generation force detection device capable of accurately detecting a tire generation force generated between a tire and a road surface, regardless of axle processing accuracy, axle mounting error, and the like. There is.

  Still another object of the present invention is to provide a wheel abnormality detection device capable of detecting the occurrence of wheel abnormality.

  In order to achieve the above object, the moment detection device of the present invention is based on the change in magnetic flux between the rotor and the stator that rotates together with the rotor, and the position is determined when a force is applied. Based on the signal generated by the signal generating means, a signal generating means for generating a signal whose magnitude periodically changes according to the position change of the rotating shaft and the rotational state of the rotating body, A feature amount detecting means for detecting a feature amount corresponding to a displacement amount according to a rotation angle of the rotating body; and correcting the feature amount so that a feature amount per one rotation of the rotating body is substantially constant. A correction amount calculating means for calculating a correction amount; a feature amount correcting means for correcting the feature amount according to a rotation angle of the rotating body based on the correction amount calculated by the correction amount calculating means; Changes depending on the position of A moment for detecting a moment applied to the rotating shaft based on a predetermined relationship based on the adjustment amount and the shaft rigidity of the rotating shaft and a corrected feature amount corrected by the feature amount correcting means And detecting means.

  In the moment detection device of the present invention, the feature amount detection means detects the feature amount corresponding to the positional deviation amount of the rotating shaft based on the signal generated by the signal generation means according to the rotation angle of the rotating body, and corrects it. The amount calculation means calculates a correction amount for correcting the feature amount so that the feature amount per rotation of the rotating body is substantially constant. The feature amount correcting unit corrects the feature amount according to the rotation angle of the rotating body based on the correction amount calculated by the correction amount calculating unit, and the moment detecting unit A moment applied to the rotating shaft is detected based on a predetermined relationship based on the shaft rigidity of the rotating shaft and the corrected feature amount corrected by the feature amount correcting means.

  The moment detection device of the present invention corrects the feature amount detected according to the rotation angle of the rotating body so that the feature amount per rotation of the rotating body is substantially constant. Therefore, the moment applied to the rotating shaft of the rotating body can be detected with high accuracy.

  In order to achieve the above object, the tire generating force detection device according to the present invention provides a reference for rotating a tire based on a change in magnetic flux between a rotor and a stator that rotate together with the tire attached to the vehicle. And a signal generating means for generating a signal whose magnitude periodically changes in accordance with the change in position of the rotating shaft and the rotational state of the tire when the force is applied, and the signal generated by the signal generating means Based on the feature amount detecting means for detecting the feature amount corresponding to the positional deviation amount of the rotating shaft according to the rotation angle of the tire, and the feature amount so that the feature amount per one rotation of the tire becomes substantially constant. Correction amount calculating means for calculating a correction amount for correcting the correction amount, and feature amount correcting means for correcting the feature amount according to the rotation angle of the tire based on the correction amount calculated by the correction amount calculating means; The rotation Based on a predetermined relationship based on the feature amount that changes due to the positional deviation and the axial rigidity of the rotating shaft, the corrected feature amount corrected by the feature amount correcting means, and the mechanism information of the tire The tire generating force detecting means for detecting the tire generating force generated between the tire and the road surface is provided.

  In the tire generating force detection device of the present invention, the feature amount detection means detects a feature amount corresponding to the amount of positional deviation of the rotating shaft according to the rotation angle of the tire based on the signal generated by the signal generation means, The correction amount calculation means calculates a correction amount for correcting the feature amount so that the feature amount per one rotation of the tire becomes substantially constant. The feature amount correcting unit corrects the feature amount according to the tire rotation angle based on the correction amount calculated by the correction amount calculating unit, and the tire generating force detecting unit changes due to the positional deviation of the rotation shaft. Based on the relationship determined in advance based on the feature amount and the shaft rigidity of the rotating shaft, the corrected feature amount corrected by the feature amount correcting means, and the tire mechanism information, between the tire and the road surface. The generated tire generating force is detected.

  The tire generation force detecting device of the present invention corrects the feature amount detected according to the rotation angle of the tire so that the feature amount per one rotation of the tire becomes substantially constant. Regardless of error or the like, it is possible to accurately detect the tire generating force generated between the tire and the road surface.

  In order to achieve the above object, the wheel abnormality detection device according to the present invention serves as a reference for rotating the tire based on a change in magnetic flux between the rotor and the stator rotating together with the tire attached to the vehicle. And a signal generating means for generating a signal whose magnitude periodically changes in accordance with a change in the position of the rotating shaft that shifts its position when a force is applied and the rotational state of the tire, and a signal generated by the signal generating means. And a feature amount detecting means for detecting a feature amount corresponding to a positional deviation amount of the rotating shaft according to a rotation angle of the tire, and the feature amount so that the feature amount per one rotation of the tire is substantially constant. Correction amount calculating means for calculating a correction amount for correcting the correction amount, a storage means for storing a reference correction amount, and a fluctuation amount of the correction amount calculated by the correction amount calculating means from the reference correction amount. Fluctuation amount calculation And stage, on the basis of the variation amount calculated by the fluctuation amount calculating means, and the abnormality detecting means for detecting a wheel abnormality, comprising the.

  In the wheel abnormality detection device of the present invention, the feature amount detection means detects the feature amount corresponding to the positional deviation amount of the rotating shaft based on the signal generated by the signal generation means according to the rotation angle of the tire, and corrects it. The amount calculation means calculates a correction amount for correcting the feature amount so that the feature amount per one rotation of the tire becomes substantially constant. The fluctuation amount calculating means calculates the fluctuation amount from the reference correction amount stored in the storage means for the correction amount calculated by the correction amount calculating means, and the abnormality detecting means is calculated by the fluctuation amount calculating means. A wheel abnormality is detected based on the fluctuation amount.

  The wheel abnormality detection device of the present invention can detect the occurrence of wheel abnormality on the contrary from the amount of change in the correction amount associated with the occurrence of wheel abnormality.

  According to the moment detection device of the present invention, it is possible to accurately detect the moment applied to the rotating shaft of the rotating body regardless of the eccentricity of the rotating body. Further, according to the tire generation force detecting device of the present invention, it is possible to accurately detect the tire generation force generated between the tire and the road surface regardless of the processing accuracy of the axle, the mounting error of the axle, and the like. Furthermore, according to the wheel abnormality detection device of the present invention, the occurrence of wheel abnormality can be detected and notified to the driver.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
(Detection principle)
When the vehicle turns, various forces are generated on the tire and the axle. When the tire rolling direction of the tire contact surface is the x-axis, the tire rotation axis direction is the y-axis, and the direction orthogonal to each of the x-axis and the y-axis is the z-axis, the force in each axial direction (Fx, Fy, Fz) And moments (Mx, My, Mz) around each axis are generated. The force Fy generated in the direction of the tire rotation axis is generally called “lateral force”.

  As shown in FIG. 1, when a lateral force is generated in the tire, a moment Mx is generated in a bearing (bearing), and thereby the axle is vertically changed. The amount of axle displacement is thought to depend on the moment stiffness of the bearing. FIG. 2 is a measurement result showing the relationship between the moment Mx and the vertical displacement of the axle. It can be seen that the moment Mx and the amount of displacement of the axle have a substantially linear relationship.

  As shown in FIG. 1, the moment Mx due to the lateral force is given by the product of the tire radius R and the lateral force Fy. Therefore, if the amount of displacement of the axle is known, the moment Mx is obtained from the relationship between the moment Mx and the amount of displacement of the axle shown in FIG. 2, and the obtained moment Mx is divided by the tire radius R to obtain the lateral force Fy. Can be requested.

  In the above, an example in which the moment Mx is obtained from the relationship between the moment Mx and the amount of displacement of the axle has been described. However, instead of the amount of displacement of the axle, the output signal strength of the wheel speed sensor etc. “changes according to the amount of displacement of the axle. Feature amount "can be used. In this case, if the feature amount is known, the moment Mx can be obtained from the relationship between the previously obtained moment Mx and the feature amount. Alternatively, the relationship between the lateral force Fy and the feature amount may be obtained in advance, and the lateral force Fy may be obtained from this relationship.

(Tire generating force detection device)
As shown in FIG. 3, the tire generating force detection device according to the present embodiment includes wheel speed sensors 10 and 12 that detect the rotational speed of the tire, and a control unit 100 that is configured by a computer or the like. The control unit 100 calculates a feature amount using two sensor signals output from each of the wheel speed sensors 10 and 12, detects a tire generation force from the feature amount, and detects a wheel abnormality. In the present embodiment, the intensity ratio of the two sensor signals corresponds to the “feature amount”.

  The wheel speed sensor 10 includes a gear-shaped rotor 34 made of a magnetic material and a cylindrical electromagnetic pickup 36. The wheel speed sensor 12 uses a rotor 34 that is common to the wheel speed sensor 10, and is composed of the rotor 34 and a cylindrical electromagnetic pickup 42. In the present embodiment, each of the wheel speed sensors 10 and 12 is attached to the axle 44 so that the rotor 34 rotates together with the tire, as shown in FIGS. 4 (A) and 4 (B) and FIG. Is held in a knuckle 48 fixed to the vehicle body side. In addition, each of the electromagnetic pickups 36 and 42 is attached to the knuckle 48 so that the tip of each of the electromagnetic pickups 36 and 42 is inserted through the knuckle 48 and faces the outer periphery of the rotor 34.

  The electromagnetic pickup 42 of the wheel speed sensor 12 is attached such that its central axis is parallel to the vehicle traveling direction (the direction of the tire center plane). That is, it is attached so that the central axis of the cylinder faces the x-axis direction. Further, the electromagnetic pickup 36 of the wheel speed sensor 10 is mounted such that its central axis intersects the vehicle traveling direction at a predetermined angle (about 45 ° in the figure).

  As shown in FIG. 6, the electromagnetic pickup 36 includes a magnet 38 and a coil 40, and is fixed to a knuckle 48 so that the tip portion is separated from the rotor 34 by several mm. In this wheel speed sensor, when the rotor 34 rotates, the magnetic flux passing through the coil 40 changes, and a sinusoidal AC voltage is induced. For example, in a 48-tooth rotor, 48 cycles of a sine wave signal are generated per tire rotation. The electromagnetic pickup 42 has the same configuration as that of the electromagnetic pickup 36 and will not be described.

  The control unit 100 includes a sampling signal generation circuit 14 that generates a sampling signal, a feature amount detection unit 16 that detects a feature amount according to the sampling signal, and a feature amount average value calculation that calculates an average value of the detected feature amount per tire rotation. Unit 18, correction coefficient deriving unit 20 for deriving a correction coefficient for each detected feature amount, feature amount correcting unit 22 for correcting a feature amount using the derived correction coefficient, feature amount and tire under a predetermined rotational speed A relationship storage unit 28 that stores a relationship with the generated force in advance, and a tire generated force detection unit 24 that detects the tire generated force from the feature amount corrected by the feature amount correction unit 22 based on this relationship are provided.

  Further, the control unit 100 determines whether or not to permit the update of the correction coefficient stored in the correction coefficient storage unit 30 and the correction coefficient storage unit 30 that stores the correction coefficient derived by the correction coefficient deriving unit 20. An update permission determination unit 26 is provided. The update permission determination unit 26 is connected to a lateral force change detection unit 33 that easily detects a change in lateral force, and updates a correction coefficient based on a determination signal input from the lateral force change detection unit 33. It is determined whether or not to permit.

  Furthermore, the control unit 100 includes a correction coefficient fluctuation detecting unit 31 that detects a fluctuation amount of the correction coefficient, and an abnormality detection unit 32 that detects a wheel abnormality from the detected fluctuation amount of the correction coefficient. The correction coefficient fluctuation detecting unit 31 compares the new correction coefficient derived by the correction coefficient deriving unit 20 with the reference correction coefficient (reference correction coefficient) stored in the correction coefficient storage unit 30 to determine the correction coefficient. Detect fluctuation amount. In addition, the anomaly detector 32 is connected to a notification device 35 for notifying a wheel abnormality to the outside based on an anomaly signal from the anomaly detector 32.

(Detection of tire generation force)
Next, the tire generation force detection procedure in the tire generation force detection device will be described.
(1) Detection of Feature Value When each of the output signals of the wheel speed sensors 10 and 12 is input to the feature value detection unit 16, the feature value detection unit 16 calculates the intensity value of each output signal. In this embodiment, the effective value (RMS) of the AC signal is used as an index indicating the intensity value of the output signal. Instead of the effective value, the maximum amplitude value, the peak-to-peak value, or the like can be used as an index.

  The sampling signal generation circuit 14 generates a sampling signal for sampling the effective value at a predetermined interval based on the output signal of the wheel speed sensor 10. In the feature amount detection unit 16, the calculated effective value is sampled according to the input sampling signal, and an effective value ratio (intensity ratio) that is a “feature amount” is calculated from each sampled effective value.

  In the present embodiment, as shown in the following equation, the effective value ratio is calculated based on the effective value of the signal of the sensor 2.

  The effective value ratio calculated by the feature amount detection unit 16 is output to the feature amount average value calculation unit 18. For example, in a wheel speed sensor using a 48-tooth rotor, an effective value ratio is detected for each tooth (1/48 rotations), and 48 effective value ratios are output per tire rotation.

  The above effective value changes according to the amount of displacement of the axle. As can be seen from FIG. 5, when the axle 44 is not displaced, the gap (distance) between the rotor 34 and the electromagnetic pickups 36 and 42 does not change, but the axle 44 is displaced. Occurs, the gap between the rotor 34 and the electromagnetic pickups 36 and 42 changes.

  As a result, the magnetic resistance of each coil of the electromagnetic pickups 36 and 42 changes, and the induced voltage generated in each coil changes. If the axle is displaced in the vertical direction and the gap between the tip of the pickup and the rotor 34 is widened, the magnetic resistance increases, the induced voltage decreases, and the amplitude of the output signal of the wheel speed sensor decreases.

  FIG. 7 shows the measurement result of the effective value of the sensor signal when the lateral force (slip angle) is changed for each of the wheel speed sensors 10 and 12. The wheel load Fz is 2500 N, and the rotational speed is 30 rad / s. The effective value of the wheel speed sensor 10 (sensor 1) varies depending on the lateral force, but the effective value of the wheel speed sensor 12 (sensor 2) is insensitive to the lateral force. The characteristic differs depending on the mounting position of the wheel speed sensor because the axle is displaced up and down when a lateral force is generated, so that the gap at sensor 2 hardly changes and the gap at sensor 1 changes more than that. is there.

In the present embodiment, the effective value ratio (intensity ratio) of the two wheel speed sensors is used as the “feature amount” instead of the effective value of one wheel speed sensor. When the effective value ratio (intensity ratio) of the two wheel speed sensors is used, most of the speed dependence is canceled between the two effective values, and the relationship between the effective value ratio and the rotational speed is substantially linear. Lateral force detection accuracy is improved.
(2) Correction of Feature Value FIG. 8 shows the measurement result of the effective value ratio when the lateral force (slip angle) is changed. FIG. 8 shows a change in the effective value ratio when the effective value is obtained for each section with two periods (1/48 rotations) of the sensor signal as one section. The horizontal axis is the number (address) of the rotor tooth corresponding to each section, and the effective value ratio is detected according to each tooth of the 48-tooth rotor.

  As can be seen from FIG. 8, the effective value ratio includes periodic fluctuations (swells) in which one rotation of the tire is one cycle. As already mentioned, this variation is due to shaft eccentricity. The fluctuation range of the effective value ratio is an amount that cannot be ignored when converted into the lateral force. If the lateral force is obtained based on the actually measured effective value ratio, the accurate lateral force cannot be detected.

Therefore, in the present embodiment, the effective value ratio that is the “feature value” is corrected by the following procedures (a) to (c).
(A) Calculation of Feature Value Average Value First, when effective value ratios are sequentially input to the feature value average value calculation unit 18, the average value of the effective value ratio α _v (k) per tire rotation according to the following equation (1). The value α _m (k) is calculated. For example, in a wheel speed sensor using a 48-tooth rotor, 48 effective value ratios are output by one rotation of the tire, so an average value for the 48 effective value ratios is calculated.

Here, N is the number of divisions when the rotation angle is divided, and N = 48 when an effective value or an effective value ratio is obtained for each section with 1/48 rotation as one section. K is an address of 0 to 47 teeth.
(B) Derivation of Correction Coefficient The average value calculated by the feature amount average value calculation unit 18 is output to the correction coefficient derivation unit 20. The correction coefficient deriving unit 20 derives a correction coefficient h (k) according to the following equation (2). The correction coefficient h (k) represents a change rate of the effective value ratio α _v (k) of each section with respect to the average value α _m (k), and can be called an eccentricity correction coefficient.

(C) Correction The correction coefficient h (k) derived by the correction coefficient deriving unit 20 is output to the feature amount correcting unit 22. The feature quantity correcting section 22, the effective value ratio by multiplying the correction coefficient h (k) to the effective value ratio _{α v (k) α v (} k) is corrected in accordance with the following formula (3), the correction effective value ratio alpha _h (K) is required.

The correction coefficient h _f (k) represented by the following equation (4) may be obtained in consideration of disturbance from the road surface. This correction coefficient h _f (k) is a correction coefficient that has been subjected to a filtering process. By multiplying the effective value ratio α _v (k) by the correction coefficient h _f (k), disturbance from the road surface is also removed. be able to.

Here, K _w is a constant that satisfies the condition of 0 <K _w <1. _Kw is a value corresponding to the time constant of the low-pass filter. When K _w = 0, the filtering process is not performed, and the degree of the filtering process increases as K _w approaches 1.

  Further, although the correction coefficient is always derived by the correction coefficient deriving unit 20, the feature amount can be corrected using the same correction coefficient as long as the lateral force does not change. Accordingly, the correction coefficient stored in advance in the correction coefficient storage unit 30 is read out, and the feature amount is corrected using this.

  FIG. 9 shows a result of deriving the above-described correction coefficient h (k) with 10 combinations of speed, lateral force, and wheel load. In this graph, the calculation results of each combination are plotted, but it can be seen that the correction coefficient h (k) has substantially the same pattern.

  The fact that the correction coefficient h (k) is constant regardless of the driving conditions means that the correction coefficient can be calculated under any driving condition and that the correction coefficient once obtained can be used even under different driving conditions. I mean.

  For example, when the feature amount is corrected under the traveling condition of the wheel load Fz: 2500 N, the slip angle: 2 °, and the rotational speed: 30 rad / s, as shown in FIG. 10A, the wheel load Fz: 2500 N, slip When the correction coefficient obtained under the condition of angle: 0 °, rotational speed: 30 rad / s is used, and as shown in FIG. 10B, wheel load Fz: 2500 N, slip angle: 1 °, rotational speed: It can be seen that the same correction result is obtained when the correction coefficient obtained under the condition of 40 rad / s is used.

  However, the correction described above is based on the precondition that the lateral force is constant and does not change during one rotation of the tire, for example, during straight traveling or steady turning, as can be seen from the above equation (1). Yes. Therefore, when the lateral force does not change during one rotation of the tire, the correction coefficient stored in the correction coefficient storage unit 30 is updated.

As described above, the correction coefficient deriving unit 20 derives the correction coefficient h (k). The correction coefficient storage unit 30 stores a reference correction coefficient h ₀ (k) in advance. The correction coefficient h ₀ (k) serving as a reference is an initial setting value, and a correction coefficient updated appropriately is stored. The update permission determination unit 26 permits the correction coefficient stored in the correction coefficient storage unit 30 to be updated with the derived correction coefficient h (k) based on the determination signal input from the lateral force change detection unit 33. It is determined whether or not to do.

If the change in lateral force during one rotation of the tire is not detected by the lateral force change detection unit 33, an update permission signal is input from the update permission determination unit 26 to the correction coefficient derivation unit 20, and a new correction coefficient h ( In k), the correction coefficient stored in the correction coefficient storage unit 30 is updated. The lateral force change detection unit 33 detects whether there is a change in lateral force. For example, when the change amount of the difference between the output signals of the left and right wheel speed sensors is zero or within a predetermined range, the steering speed is zero. Alternatively, it can be determined that the lateral force has not changed when the acceleration sensor is within the predetermined range, or when the change amount of the acceleration sensor is zero or within the predetermined range.
(3) Detection of Tire Generating Force Next, the tire generating force detection unit 24 detects the tire generating force. The relationship storage unit 28 stores a relationship between the lateral force and the effective value ratio as a map. The tire generation force detection unit 24 reads this map from the relationship storage unit 28, detects a lateral force corresponding to the correction effective value ratio obtained by the feature amount correction unit 22 using this map, and outputs a detection signal.
(Detection of wheel abnormality)
Next, a procedure for detecting a wheel abnormality in the tire generating force detection device will be described.

The correction coefficient derivation unit 20 also outputs the derived correction coefficient h (k) to the correction coefficient fluctuation amount detection unit 31. When the correction coefficient h (k) is input to the correction coefficient fluctuation amount detection unit 31, the reference correction coefficient h ₀ (k) is read from the correction coefficient storage unit 30, and the derived correction coefficient h (k ) Is calculated from the correction coefficient h ₀ (k) serving as the reference.

Here, as the reference correction coefficient h ₀ (k), for example, a correction coefficient derived when it is possible to clearly determine that the wheel is in a normal state, such as at the time of factory shipment or after completion of legal inspection, is used. Can do. In addition, a correction coefficient derived when the operator determines that the wheel is in a normal state may be used. In this case, when the operator determines that the wheel is in a normal state, a trigger signal for setting a reference correction coefficient h ₀ (k) is generated, and the correction coefficient derived according to the signal is captured. You may do it.

  As shown in FIG. 11, in an abnormal state of a wheel, that is, when an abnormality occurs in elements (hub, bearing, wheel, tire, etc.) constituting the wheel, such as a decrease in tire air pressure, a change occurs in the feature amount. The correction coefficient varies. Therefore, the wheel abnormality can be detected by detecting the amount of change.

As an index of variation, as expressed by the following equation (5), the sum of the absolute values of the difference between the correction coefficient h (k) and the correction coefficient h ₀ (k) per tire rotation is used. it can. Further, as expressed by the following equation (6), the sum of the squares of the difference between the correction coefficient h (k) and the correction coefficient h ₀ (k) per tire rotation may be used. Here, k represents the address of 0 to 47 teeth corresponding to the 48-tooth rotor.

  When the calculated fluctuation amount is input to the abnormality detection unit 32, the abnormality detection unit 32 determines whether or not the fluctuation amount exceeds a predetermined threshold value. When it is determined that the fluctuation amount exceeds the threshold value, an abnormal signal is input to the alarm device 35. When an abnormal signal is input, the alarm 35 notifies the outside that a wheel abnormality has occurred.

In the above description, the fluctuation amount is calculated based on the correction coefficient h ₀ (k) that is the initial setting value. However, the fluctuation amount may be calculated based on the correction coefficient updated immediately before. If the correction coefficient updated immediately before is used as a reference, in a case where the abnormality gradually increases, it is conceivable that it is difficult to detect the wheel abnormality because the fluctuation amount becomes small. However, if a large difference appears with the correction coefficient updated immediately before, it is assumed that a sudden abnormality has occurred. By constantly comparing the derived correction coefficient with the correction coefficient updated immediately before, it is possible to detect the occurrence of these sudden abnormalities.

  For example, as shown in FIG. 12, when an abnormality is detected based on each of two types of fluctuation amounts, that is, (1) the correction coefficient stored when it is determined to be normal is used as a reference value, and the fluctuation amount is abnormal. Different threshold values may be used in the case of detecting an abnormality and (2) the case where an abnormality is detected with the amount of variation using the correction coefficient updated immediately before as a reference value. In FIG. 12, the threshold value (1) is set corresponding to the method (1), and the threshold value (2) is set corresponding to the method (2). As shown in the figure, when a sudden abnormality is detected as in (2), the wheel abnormality can be detected by setting a larger threshold value.

  Since the correction coefficient fluctuates in a wheel abnormality state, it is preferable not to update the correction coefficient after the abnormality is detected. In addition, since a case in which an abnormality is gradually enlarged and detected is assumed, the correction coefficient may be reset to an initial setting value after the abnormality is detected.

  As described above, in the present embodiment, the effective value ratio of the two wheel speed sensors is used as the feature amount, and the effective value ratio is corrected so that the periodic fluctuation caused by the shaft eccentricity is reduced, Since the lateral force is detected using the corrected effective value ratio, the lateral force can be detected with high accuracy regardless of the processing accuracy of the axle, the mounting error of the axle, and the like.

  Further, since the correction coefficient varies with the occurrence of the wheel abnormality, the occurrence of the wheel abnormality can be detected by determining whether or not the variation amount of the correction coefficient has exceeded a predetermined threshold.

(Other embodiments)
Although the example using the electromagnetic pickup coil type wheel speed sensor has been described above, a Hall IC type wheel speed sensor using the Hall effect may be used.

  Further, as shown in FIGS. 13A and 13B, a wheel speed sensor including a magnetized rotor 50 may be used. On one surface of the rotor 50, a large number of permanent magnets 54 are arranged along the outer periphery of the rotor 50 so that the south pole and the north pole are alternated.

  The rotor 50 is attached to the axle 44 so as to rotate together with the tire, and is housed in a knuckle 48 that is fixed to the vehicle body side in order to hold the bearing 46. The pickup 52 having a coil is attached to the knuckle 48 so that the tip of the pickup 52 is inserted through the knuckle 48 and faces the permanent magnets 54 arranged on the outer periphery of the rotor 50 at a predetermined interval (about several mm). It has been.

  In this wheel speed sensor, when the rotor 50 rotates with the permanent magnet 54, an induction voltage is generated in the coil of the pickup 52 by electromagnetic induction with the permanent magnet 54. If the axle is displaced in the vertical direction and the gap between the tip of the pickup 52 and the rotor 50 is widened, the induced voltage is reduced and the amplitude of the output signal of the wheel speed sensor is reduced.

  In the above, the electromagnetic pickup of one wheel speed sensor of the two wheel speed sensors is attached so that the central axis thereof faces the x-axis direction, and the electromagnetic pickup of the other wheel speed sensor is attached to the central axis. However, the mounting position of the two wheel speed sensors is not limited to this. It is only necessary that two wheel speed sensors be attached so that signals having different magnitudes are generated when the axle is displaced.

  When detecting a lateral force, it is preferable that the electromagnetic pickup of at least one wheel speed sensor is attached so that the central axis thereof faces the z-axis direction (the vehicle vertical direction). When the lateral force is generated, the axle is displaced in the vertical direction, so that the amount of change in the gap is maximized and the detection sensitivity is the highest.

  For example, an example of a wheel speed sensor including a magnetized rotor (rotor) 50 shown in FIG. The two wheel speed sensors use a common rotor 50.

  In this case, as shown in FIG. 14, the pickup 52A of one wheel speed sensor is attached to the knuckle 48 so that its central axis faces the x-axis direction, and the electromagnetic pickup 52B of the other wheel speed sensor is It is preferable to attach so that the central axis faces the z-axis direction. The knuckle 48 to which the pickups 52A and 52B are attached corresponds to the stator.

  Further, as shown in FIG. 15, it is more preferable that the electromagnetic pickups 52A and 52B are attached to the knuckle 48 so that the center axis thereof faces the z-axis direction.

  Further, as shown in FIG. 16, the electromagnetic pickups 52A and 52B are attached to the knuckle 48 so that the central axis thereof faces the z-axis direction, and the electromagnetic pickups 52C and 52D are arranged so that the central axis thereof faces the x-axis direction. It is possible to detect a moment and a tire generating force correlated with the lateral displacement of the axle.

  In the present embodiment, an example in which two wheel speed sensors are used has been described, but the strength of one wheel speed sensor may be used as a feature amount.

It is explanatory drawing explaining the vertical displacement of the axle shaft by the lateral force Fy which generate | occur | produced on the tire. It is the graph which showed the relationship between the moment Mx and the vertical displacement amount of an axle shaft. It is a block diagram which shows schematic structure of a tire generating force detection apparatus. (A) And (B) is a figure which shows the attachment state of a wheel speed sensor. It is sectional drawing along the rotating shaft which shows the structure of a wheel speed sensor. It is sectional drawing along the central axis of the electromagnetic pick-up of a wheel speed sensor. It is a graph which shows the relationship between lateral force and the effective value of a sensor output signal. It is a graph which shows the change with respect to the tire rotation angle (tooth address) of an effective value ratio. It is a graph which shows the change with respect to the tire rotation angle (tooth address) of the correction coefficient under a plurality of running conditions. (A) And (B) is a graph which shows the change with respect to the tire rotation angle (tooth address) of the effective value ratio before and behind correction | amendment when correct | amending using the same correction factor on different driving | running | working conditions. It is a graph which shows the change with respect to the tire rotation angle (tooth address) of a correction coefficient between a normal state and an abnormal state of a wheel. It is a graph which shows the relationship between the time-dependent change amount of the correction coefficient, and the threshold value. It is a figure which shows the structure of the wheel speed sensor provided with the magnetized rotor, (A) is sectional drawing along a rotating shaft, (B) is an enlarged view of a rotor part. It is the schematic which shows an example of the attachment state of a several wheel speed sensor. It is the schematic which shows the other example of the attachment state of a some wheel speed sensor. It is the schematic which shows the further another example of the attachment state of a several wheel speed sensor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10, 12 Wheel speed sensor 100 Control unit 14 Sampling signal generation circuit 16 Feature quantity detection part 18 Feature quantity average value calculation part 20 Correction coefficient derivation part 22 Feature quantity correction part 24 Tire generation force detection part 26 Update permission determination part 28 Relation memory Unit 30 correction coefficient storage unit 31 correction coefficient fluctuation detection unit 32 abnormality detection unit 33 lateral force sensor 34 rotor 35 alarm device 36, 42 electromagnetic pickup 38, 40 coil 44 axle 46 bearing 48 knuckle

Claims (13)

Based on the change in magnetic flux between the rotor and the stator rotating together with the rotating body, it becomes a reference for rotating the rotating body, and depending on the position change of the rotating shaft that shifts its position when a force is applied and the rotating state of the rotating body Signal generating means for generating a signal whose magnitude changes periodically,
Feature amount detection means for detecting a feature amount corresponding to the amount of positional deviation of the rotating shaft according to a rotation angle of the rotating body, based on a signal generated by the signal generation means;
Correction amount calculation means for calculating a correction amount for correcting the feature amount so that the feature amount per one rotation of the rotating body is substantially constant;
Feature amount correction means for correcting the feature amount according to the rotation angle of the rotating body based on the correction amount calculated by the correction amount calculation means;
Based on a predetermined relationship based on the feature amount that changes due to the positional deviation of the rotating shaft and the shaft rigidity of the rotating shaft, and the corrected feature amount corrected by the feature amount correcting means, A moment detection means for detecting the moment applied to the rotating shaft;
Moment detection device with   The correction amount calculating means calculates a correction amount represented by a difference or ratio between a feature amount corresponding to a rotation angle of the rotating body and an average value of the feature amount per rotation of the rotating body. The described moment detection device. A storage means for storing the correction amount calculated by the correction amount calculation means or a preset correction amount;
The moment detecting device according to claim 2, wherein the feature amount correcting unit corrects the feature amount according to a rotation angle of the rotating body based on a correction amount stored in the storage unit. A determination unit for determining whether or not to update the correction amount stored in the storage unit;
The moment detection device according to claim 2 or 3, wherein the correction amount stored in the storage unit is updated based on a determination result of the determination unit. Based on a change in magnetic flux between a rotor and a stator that rotate together with a tire attached to a vehicle, a change in the position of a rotating shaft that is a reference for rotating the tire and shifts its position when a force is applied, and rotation of the tire Signal generating means for generating a signal whose magnitude periodically changes according to the state;
Feature quantity detection means for detecting a feature quantity corresponding to the amount of positional deviation of the rotating shaft in accordance with a rotation angle of the tire based on a signal generated by the signal generation means;
Correction amount calculating means for calculating a correction amount for correcting the feature amount so that the feature amount per one rotation of the tire is substantially constant;
Feature amount correction means for correcting the feature amount according to the rotation angle of the tire based on the correction amount calculated by the correction amount calculation means;
Predetermined relationship based on the feature amount that changes due to the positional deviation of the rotating shaft and the shaft rigidity of the rotating shaft, the corrected feature amount corrected by the feature amount correcting means, and the mechanism information of the tire Tire generating force detecting means for detecting tire generating force generated between the tire and the road surface based on
A tire generation force detection device comprising:   6. The correction amount calculation unit according to claim 5, wherein the correction amount calculation means calculates a correction amount represented by a difference or a ratio between a feature amount corresponding to a rotation angle of the tire and an average value of the feature amount per rotation of the tire. Tire force detection device. A storage means for storing the correction amount calculated by the correction amount calculation means or a preset correction amount;
The tire generation force detection device according to claim 6, wherein the feature amount correction unit corrects the feature amount according to a rotation angle of the tire based on a correction amount stored in the storage unit. A determination unit for determining whether or not to update the correction amount stored in the storage unit;
The tire generation force detection device according to claim 6 or 7, wherein the correction amount stored in the storage unit is updated based on a determination result of the determination unit. Based on a change in magnetic flux between a rotor and a stator that rotate together with a tire attached to a vehicle, a change in the position of a rotating shaft that is a reference for rotating the tire and shifts its position when a force is applied, and rotation of the tire Signal generating means for generating a signal whose magnitude periodically changes according to the state;
Feature quantity detection means for detecting a feature quantity corresponding to the amount of positional deviation of the rotating shaft in accordance with a rotation angle of the tire based on a signal generated by the signal generation means;
Correction amount calculating means for calculating a correction amount for correcting the feature amount so that the feature amount per one rotation of the tire is substantially constant;
Storage means for storing a reference correction amount;
A fluctuation amount calculating means for calculating a fluctuation amount of the correction amount calculated by the correction amount calculating means from a reference correction amount;
An abnormality detection means for detecting a wheel abnormality based on the fluctuation amount calculated by the fluctuation amount calculation means;
A wheel abnormality detection device comprising:   10. The correction amount calculation unit according to claim 9, wherein the correction amount calculation unit calculates a correction amount represented by a difference or ratio between a feature amount corresponding to a rotation angle of the tire and an average value of the feature amount per rotation of the tire. Wheel abnormality detection device.   The abnormality detecting means compares the fluctuation amount calculated by the fluctuation amount calculating means with a predetermined threshold value, and determines that a wheel abnormality has occurred when the fluctuation amount exceeds a predetermined threshold value, and detects a wheel abnormality. The wheel abnormality detection device according to claim 9 or 10.   The wheel abnormality detection device according to any one of claims 9 to 11, wherein the reference correction amount is a correction amount stored when it is determined that the wheel is normal.   The wheel abnormality detection device according to any one of claims 9 to 11, wherein the reference correction amount is a correction amount updated immediately before.

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