JP4619870B2 - Alignment state detection device - Google Patents

Description

  The present invention relates to an alignment state detection device, and more particularly to wheel alignment state detection in an alignment state detection device mounted on a vehicle.

  When the vehicle travels in a state where the wheel alignment is out of order due to deterioration over time or passage of an excessive level difference, there is a concern about deterioration of tires and suspensions and a decrease in marginal performance during turning.

In order to cope with this, an apparatus for detecting the alignment state is conventionally known. The vehicle steering device described in Patent Document 1 and mounted on a vehicle that is automatically steered is an example. According to this steering device, during straight traveling by steering control, the steering angle is equal to or greater than a predetermined angle, and the steering control torque instructed to the steering actuator by the controller for automatic steering is equal to or greater than the predetermined value. If it continues for a predetermined time, an alarm is output that the alignment state is abnormal.
JP 2002-274403 A

  However, this vehicle steering device is premised on automatic steering, and an alignment abnormality cannot be detected by a vehicle that does not perform such control. Further, since the wheel alignment abnormality is detected from the steering angle and the steering control torque, it is difficult to detect the delicate alignment state of each wheel with high accuracy. For example, when each wheel is toe-in, it cannot be accurately detected that the properness is lost.

  The present invention has been made in view of such circumstances, and an object thereof is to detect a wheel alignment state with high accuracy.

  Another object of the present invention is to realize detection of the wheel alignment state with a simple device configuration even in a vehicle that is not automatically steered.

  In order to solve this problem, the first invention provides an alignment state detection device that detects the state of wheel alignment of a vehicle. The alignment state detection device includes a tire force sensor and an alignment state determination unit. A longitudinal force and a lateral force acting on each tire are detected by the tire force sensor. When the vehicle is traveling straight and neither driving force nor braking force is applied to the vehicle, the alignment state determination unit determines the longitudinal force and lateral force detected by the tire force sensor for each tire. When the resultant force has a direction or magnitude outside the predetermined first determination range, the determination of the vehicle wheel alignment state is performed.

  In the first invention, as a result of the determination by the alignment state determination unit, when any direction or magnitude of the resultant force for each tire is outside the predetermined first determination range, The state of alignment may be notified.

  Furthermore, in the present invention, it is preferable that the alignment state determination unit further includes a next determination result memory for performing the next determination for a predetermined second determination range (danger range) and recording the result. The second determination range is a hollow region sandwiched between an outer locus that defines the first determination range and an inner locus that is concentric with the outer locus. As described above, when the vehicle is traveling straight and no driving force or braking force is applied to the vehicle, the alignment state determination unit detects the longitudinal force detected by the tire force sensor for each tire. Whether or not the resultant force of the lateral force has the direction and size of the second determination range is determined. As a result of the determination by the alignment state determination unit, when any direction and magnitude of the resultant force for each tire is in the second determination range, the determination result memory stores the direction and magnitude of the resultant force for each tire. Is memorized.

  Similar to the first invention, the second invention provides an alignment state detection device that detects the state of wheel alignment of the vehicle. Similarly, the alignment state detection device includes a tire force sensor that detects a longitudinal force and a lateral force acting on each tire, and further includes a next longitudinal force value correction unit and an alignment state determination unit. . The longitudinal force value correction unit corrects the detected value of the longitudinal force so as to exclude the effect of the estimated driving force and braking force on the vehicle from the detected value of the longitudinal force by the tire force sensor. When the vehicle is traveling straight ahead, the alignment state determination unit determines the resultant force of the longitudinal force corrected by the longitudinal force value correction unit and the lateral force detected by the tire force sensor for each tire within a predetermined determination range. A determination of the vehicle wheel alignment state is made when it has an outward orientation or size.

  The third invention provides an alignment state detection device for detecting the state of vehicle wheel alignment, as in the first and second inventions. Similarly, the alignment state detection device includes a tire force sensor that detects longitudinal force and lateral force acting on each tire, and further includes a first slip angle estimation unit, a second slip angle calculation unit, and a toe angle calculation unit. And an alignment state determination unit. Using the detected values of the longitudinal force and the lateral force by the tire force sensor, the first slip angle estimation unit estimates the first slip angle that is the slip angle that has actually occurred. When the toe angle is assumed to be 0 for each tire, the second slip angle calculation unit is estimated using the detected values of the vehicle body speed, lateral acceleration, yaw angular velocity, and steering angle on-board sensors (state quantity sensors). The second slip angle, which is the slip angle, is calculated. The toe angle calculation unit calculates the toe angle from the first slip angle estimated by the first slip angle estimation unit and the second slip angle calculated by the second slip angle calculation unit. When the vehicle is traveling, the alignment state determination unit determines the wheel alignment state of the vehicle when the toe angle calculated by the toe angle calculation unit is a predetermined determination range.

  Furthermore, the 4th invention is an alignment state detection apparatus which detects the state of the wheel alignment of a vehicle similarly to the 1st-3rd invention. The alignment state detection device includes a tire force sensor, a camber angle estimation unit, and an alignment state determination unit. A lateral force and a vertical force acting on each tire are detected by the tire force sensor. The camber angle estimator estimates the camber angle for each tire using the detected values of lateral force and vertical force from the tire force sensor. The alignment state determination unit determines the vehicle wheel alignment state when the camber angle estimated by the camber angle estimation unit is outside a predetermined determination range.

  According to the present invention, the longitudinal force and lateral force acting on the wheel are directly detected, and the state of wheel alignment is determined based on them, so that the detection accuracy of the alignment state is improved. Since this configuration uses sensors used in an anti-lock brake system (ABS), a traction control system (TCS), etc., the effect can be obtained with a simple configuration even in a vehicle that does not perform automatic steering control.

(First embodiment)
FIG. 1 is an explanatory diagram of a vehicle on which an alignment state detection apparatus 10 according to the first embodiment is mounted, and FIG. 2 is an explanatory diagram of forces acting on the wheels 5. FIG. 3 is a block diagram showing the main configuration of the alignment state detection apparatus 10.

  As shown in FIG. 1, this vehicle is a four-wheel drive vehicle, and four wheels on the front, rear, left and right are driven simultaneously. The power of the engine 1 is transmitted to the front and rear axles 4 through the automatic transmission 2, the center differential 3a, the front differential 3b, the rear differential 3c, and the like. By transmitting this power to the axle 4, driving torque is applied to the wheels 5, and each wheel 5 is driven. The alignment state detection apparatus 10 is mainly composed of a microcomputer and includes a CPU, a ROM, a RAM, an input / output interface, and the like.

A tire force sensor 12 is provided inside the axle 4 in the vicinity of each wheel 5. The tire force sensor 12 detects longitudinal force F _x , lateral force F _y , and vertical force F _z acting on the tire. As shown in FIG. 2, the longitudinal force F _x is a component force in the direction parallel to the wheel center plane (x-axis direction) with respect to the frictional force generated on the ground contact surface of the tire covering the outer periphery of the wheel 5, lateral force F _y is a component force in the direction perpendicular to the wheel center plane (y-axis direction). The vertical force _Fz is a vertical load acting in the vertical direction (z-axis direction).

Each of the tire force sensors 12 includes a strain gauge and a signal processing circuit that processes the output electrical signal to generate a detection signal. Since the stress generated in each axle 4 is proportional to the force acting on each corresponding tire, the stress in the x-axis, y-axis, and z-axis directions is detected by a strain gauge embedded in the axle 4, respectively. The longitudinal force F _x , the lateral force F _y , and the vertical force F _z are directly detected. For example, Japanese Patent Laid-Open Nos. 04-331336 and 10-318862 describe a more specific configuration of the tire force sensor 12. In the present alignment state detection device 10, in particular, the detected values of the longitudinal force F _x and the lateral force F _y are used.

In addition to these tire force sensors 12, a state quantity sensor 13 (FIG. 3) is provided inside the vehicle. The state quantity sensor 13 detects a vehicle state quantity that is information indicating the state of the vehicle such as the vehicle speed V, the lateral acceleration a _y , and the yaw angular velocity ω, and an operation state that is information indicating the operation state of the driver such as the steering angle θ. The amount is detected. These state quantity sensors 13 are constituted by well-known vehicle speed sensors, lateral acceleration sensors, yaw angular velocity sensors, steering angle sensors, and the like, and can be constituted by one or two or more sensors that perform various detections in combination.

  Furthermore, an engine control device, a shift control device, and a brake control device (all of which are mainly composed of a microcomputer) (not shown) are connected to the alignment state detection device 10 via a LAN. The alignment state detection device 10 receives data such as vehicle drive torque and brake torque estimated from these control devices.

  More specifically, the engine control device controls the engine 1 (FIG. 1), and estimates the engine torque from the engine speed, the throttle valve opening, the fuel injection amount, the ignition timing, the water temperature, and the oil temperature. The shift control device controls the automatic transmission 2 and receives an estimated value of the engine torque from the engine control device. The estimated engine torque value, the engine speed, the wheel speed of each wheel, the position of the shift stage, the clutch position, From the fastening force, the slip amount of the torque converter, etc., the driving torque applied to each wheel 5 or the driving force on the tire surface is estimated. The brake control device detects the operation amount of the brake pedal, monitors the rotation speed of each wheel, and estimates the brake torque of each wheel 5 or the braking force on the tire surface.

As shown in FIG. 3, the alignment state detection processing program executed by the alignment state detection device 10 mainly includes a running state determination unit 11a and an alignment state determination unit 11b. Here, in particular, the longitudinal force F _x and the lateral force F _y are detected in a state where the driving force and the braking force are not acting during the straight traveling, that is, in the state where the vehicle is traveling straight by inertia (during straight coasting). Therefore, the alignment state can be grasped more accurately, and the abnormality can be detected more precisely.

In the traveling state determination unit 11a, the vehicle speed V, the lateral acceleration a _y , the yaw angular velocity ω detected by the state quantity sensor 13, the driving torque received from the transmission control device, and the braking torque received from the brake control device. Based on the above, it is determined whether the vehicle is traveling straight, such as whether the vehicle is traveling straight ahead or whether a driving force and a braking force are acting.

In the alignment state determination unit 11b, when the vehicle is traveling straight and the driving force and the braking force are not acting (when the estimated values of the driving torque and the braking torque are close to 0), the tire force sensor 12 for each tire. It is determined whether or not the average value of the resultant force F _xy of the longitudinal force F _x and the lateral force F _y detected by the predetermined time has the direction and size of the determination range stored in the determination range memory 11c. The

Here, if it is determined that the resultant force F _xy for each tire does not have the direction or size of the determination range, the alarm output unit 14 displays a warning on the connected liquid crystal monitor, and an alarm from the speaker. An announcement is made to inform the driver that there is an abnormality in alignment. In particular, when the determination result and the magnitude of the resultant force F _xy are within the determination range but in the danger range, the fact that the resultant force F _xy is in the danger range and the magnitude and direction of the resultant force F _xy are indicated. Data is stored in the determination result memory 11d. The reason why the average value of the predetermined time is used for the resultant force F _xy is to prevent misdiagnosis caused by a road surface condition or a sudden change in torque applied to the wheels 5.

The feature of the alignment state detection device 10 described above is the detection of the alignment state based on the longitudinal force F _x and the lateral force F _y detected by the tire force sensor 12. Hereinafter, the procedure of the alignment state detection process will be described in detail. FIG. 4 is a flowchart showing the procedure of the alignment state detection process, and this process is executed by the microcomputer 11 at predetermined time intervals. FIG. 5 is an explanatory diagram of a determination range and a danger range for the resultant force F _xy according to the determinations in steps 4 and 5.

In this state detection process, first, the values of the vehicle speed V, the lateral acceleration a _y , and the yaw angular velocity ω detected by the state quantity sensor 13 (FIGS. 1 and 3) are input. The values of driving torque and braking torque (or driving force and braking force) are received from (step 1). If the drive torque and brake torque are almost 0, the vehicle speed V is not 0, and the lateral acceleration _ay and the yaw angular velocity ω are almost 0, the vehicle travels straight without driving force and braking force acting. (Yes in step 2, Yes in step 3). Since this determination result indicates that it is an appropriate timing at which the alignment state can be identified, as a subsequent process, the front / rear force F _x and the lateral force F _y detected by the tire force sensor 12 for each wheel are determined. Is input (step 4), and the tire force for each wheel (here, the resultant force F _xy of the longitudinal force F _x and the lateral force F _y ) is within the determination range stored in advance in the determination range memory 11c, It is also determined whether it is within the danger range (step 5, step 6).

As shown in FIG. 5, when the alignment state is normal, the toe-in should be maintained equally for both the front and rear wheels 5. That is, the resultant force F _xy of the longitudinal force F _x and the lateral force F _y acting on each wheel 5 is naturally a force slightly behind the vehicle. The determination range A is set, for example, to constitute an elliptical region and indicate the range of the normal direction and size of the resultant resultant force F _xy . The danger range a is an area in the determination range A that shares the outermost trajectory with the determination range A. From the outermost side of the determination range A to the inner side (from the outer ellipse that defines the determination range a to its center of gravity In a concentric manner, for example, a locus that defines the innermost side of the danger range a (an inner ellipse that defines the danger range a) is set at 85%.

In the state detection process of FIG. 4, if the average value of the resultant force F _{xy for} a predetermined time is within the determination range indicating normality but reaches the danger range (Yes in Step 5, Yes), these determination results and the direction and magnitude of the resultant force F _xy (or longitudinal force F _x and lateral force F _y ) of each wheel are stored in the determination result memory 11d (FIG. 2) (step 7).

If the average value of the resultant force F _xy is not within the determination range (No in step 5), the alarm output unit 14 notifies the driver to that effect (step 8). For example, a message is displayed on the liquid crystal monitor, and an alarm is issued from a speaker. As in the case where the resultant force is in the danger range, the value of the tire force of each wheel can be recorded in the determination result memory 11d.

According to the alignment state detection device 10 described above, the front-rear force F of each tire is obtained in a state where driving force and braking force are not acting during straight traveling, that is, in an appropriate state where only the force generated by the alignment can be measured. from the resultant force F _{xy x} and lateral force F _y, whether or not there is an abnormality in wheel alignment is determined. The longitudinal force F _x and the lateral force F _y of each tire are directly detected by a tire force sensor and have high reliability values, so that highly accurate alignment state detection is achieved. Since this detection uses sensors used for ABS or the like, the effect of high-precision state detection can be obtained with a simple configuration.

Further, when there is an abnormality in alignment, the resultant force F _xy (or the longitudinal force F _x and the lateral force F _y ) for each wheel can be appropriately recorded in the determination result memory 11d. Thus, it is not necessary to perform alignment diagnosis each time, and the wheel alignment can be adjusted smoothly. Further, since it is only necessary to adjust the alignment only when necessary, such as when the abnormality is notified, the driver can save labor and cost for the inspection.

In the alignment state detection device 10 of the present embodiment, it is determined whether or not the vehicle is traveling straight using the lateral acceleration _ay detected by the state quantity sensor 13 (FIG. 3). it may be carried out the judgment by using a total value of the lateral force F _y of the tire to be detected.

In addition, the traveling state can be more accurately identified using the steering angle θ detected by the steering angle sensor when the traveling state of the vehicle is determined. That is, it is determined that the vehicle is traveling straight only when the steering angle θ, the lateral acceleration a _y (or the total value of the lateral force F _y for each tire) and the yaw angular velocity ω are substantially zero. Can do. In addition, when the yaw angular velocity ω and the lateral acceleration a _y are 0 and the steering angle θ does not take a value close to 0, it can be notified that the alignment is abnormal.

Further, in the alignment state detection device 10 described above, a determination range of the resultant force F _xy that differs depending on the steering angle θ is set and stored in the determination range memory 11c, and stored based on the detected steering angle θ. The determination range may be read, and the alignment state may be determined based on the read range.

In the above alignment state detection device 10, or in particular an elliptical region assumes determination range A (Fig. 5), the resultant force F _xy of the longitudinal force F _x and the lateral force F _y per each wheel 5 is in its determination range A Whether or not the alignment state is appropriate is determined depending on whether or not the alignment state is appropriate, but the determination range A may be a circular region, a rectangular region, a rhombus region, or the like. Also, as simpler conditions, set the conditions such that the longitudinal force and lateral force of the left and right wheels are almost equal and the resultant force F _xy is facing inward (if it is a toe-in), and is this condition satisfied? It may be determined whether or not the alignment state is appropriate depending on whether or not.

Further, in the alignment state detection device 10 described above, it is determined whether or not the resultant force F _xy for each wheel 5 is within the determination range A, but for each of the longitudinal force F _x and the lateral force F _y individually. May be determined, and it may be determined whether or not each of the longitudinal force F _x and the lateral force F _y is in the corresponding determination range.

In a vehicle equipped with a vehicle height adjustable suspension, it is necessary to adjust the vehicle height so that the load on the diagonal wheels (the left front wheel and the right rear wheel, and the right front wheel and the left rear wheel) is not biased. For such a vehicle, the vertical force F _xy for each wheel is detected by a device similar to the alignment state detection device 10 described above, and the load bias is determined from the distribution of the values in the diagonal wheels. Display, recording, etc. can be performed.

(Second Embodiment)
FIG. 6 is a block diagram showing the main configuration of the alignment state detection apparatus 20 according to the second embodiment. Here, the parts having the same functions as those of the alignment state detection apparatus 10 (FIG. 2) according to the first embodiment are denoted by the same reference numerals. The alignment state detection device 20 of the present embodiment is different from the above-described alignment state detection device 10 mainly in that it includes a longitudinal force value correction unit 21e, but the configuration, operation, etc. of other parts not related to these are as follows. Except for the following description, the alignment state detection apparatus 10 is applied.

In the longitudinal force value correction unit 21e, the driving force and braking force for each wheel (tire) are estimated from the driving torque and braking torque for each wheel estimated by the transmission control device, the brake control device, and the like. At the same time, the longitudinal force F _x for each wheel detected by the tire force sensor 22 is corrected from the estimated driving force and braking force. The alignment state determination unit 21b determines whether or not the resultant force of the corrected longitudinal force F _x ′ and lateral force F _y for each wheel is in the determination range A and the danger range a (FIG. 5).

  Also in the alignment state detection device 20 of the present embodiment, as in the alignment state detection device 10 of the first embodiment, whether or not the alignment state is abnormal is detected when the vehicle is traveling straight ahead. The Further, unlike the alignment state detection device 10, an abnormality in alignment can be detected when a driving force and a braking force are applied.

Even the alignment state detection device 20, the longitudinal force F _x and the lateral force F _y of each tire is detected directly by the tire force sensor. The resultant force of the lateral force F _y and F _x ′ corrected for the longitudinal force F _x so that the action due to the estimated driving force and braking force is removed is a value representing the alignment state. It is a target of detection. Therefore, as long as the correction here is appropriately performed, it is possible to detect the alignment state with high accuracy.

(Third embodiment)
FIG. 7 is a block diagram showing the main configuration of the alignment state detection apparatus 30 according to the third embodiment. FIG. 8 shows the slip angle β _f and the slip angle used for calculating the toe angle T that is the object of alignment state determination. It is a figure which shows (beta) _m . Also here, parts having the same functions as those in the alignment state detection apparatus 10 according to the first embodiment are denoted by the same reference numerals.

The alignment state detection device 30 is different from the alignment state detection device 10 of the first embodiment mainly in that it includes a slip angle β _f estimation unit 31e, a slip angle β _m calculation unit 31f, and a toe angle calculation unit 31g. However, the configuration and operation of other parts not related to these are in accordance with the alignment state detection apparatus 10 except for the following description. In the alignment state detection devices 10 and 20 described above, the alignment state is detected when the vehicle is traveling straight, but in the alignment state detection device 30 of the present embodiment, the alignment state is detected even while the vehicle is turning. It can be performed.

In slip angle beta _f estimating unit 31e, which is detected by the tire force sensor 32, the longitudinal force F _x for each _wheel, the lateral force F _y, on the basis of the vertical force F _z, slip angle beta _f is estimated. That is, the slip angle β _f is detected by the state quantity sensor 33 by using a table in which the association with the tire force is stored in advance, or in a tire model such as a Fiala model or a magic formula. It is estimated from the detected value of the tire force by appropriately calculating the angle θ.

Further, the slip angle β _m calculation unit 31f obtains Δβ / Δt for the vehicle body slip angle β from the vehicle speed V, the lateral acceleration a _y , and the yaw angular velocity ω detected by the state quantity sensor 33 by the following formula 1. Further, the slip angle β _{m of} each wheel is calculated using the integral value β for that time and the steering angle θ detected by the state quantity sensor 33. Especially for the lateral acceleration a _y of the above to detect the roll angle by using a predetermined roll angle sensor, by correcting the detected value of the lateral acceleration a _y by using the detection value, the accuracy of the slip angle beta _m It is possible to raise.

In the toe angle T calculating unit 31g, the toe angle T is calculated from the sliding angle β _f and the sliding angle β _m . That is, the slip angle β _f is an accurate value obtained from the force acting on the tire, and the slip angle β _m indicates the slip angle of the tire when the toe angle T is assumed to be zero. Since the slip angles β _f and β _m and the toe angle T have a relationship as shown in FIG. 8, the toe angle T can be obtained by the following equation 2.

  In the alignment state determination unit 31b, whether or not the toe angle T has the size of the determination range stored in the determination range memory 31c in advance (usually about 0 to 2 ° inward), and the size of the danger range. It is determined whether or not. If the toe angle T is outside the determination range, the alarm output unit 34 notifies the driver, and if the toe angle T is within the danger range, the toe angle T for each wheel is recorded in the determination result memory 31d.

In the alignment state detection device 30 of the present embodiment, it is determined whether or not the toe angle T of each wheel is within the determination range, but the toe angles T of the four tires are in the same direction even within the determination range. Abnormality can be detected by detecting the deviation. That is, compared with the vector of the tire force and total longitudinal force F _x and the lateral force F _y for each wheel, an acceleration vector of the vehicle by the longitudinal and lateral acceleration sensor. If the angle between the two vectors is always deviated by a certain angle, the toe angles of the four wheels are considered to be deviated in the same direction. Output.

Here, it is assumed that the vertical force _Fz is detected by the tire force sensor 32. However, when the vertical force _Fz is unknown, the acceleration in the front / rear / left / right direction is detected and the detected acceleration is detected. It may be estimated from Without detecting directly by the tire force sensors 32 a longitudinal force F _x, brake torque, the engine torque may be estimated from the driving torque or the like.

In estimating the slip angle β _f and the slip angle β _m , by taking into account compliance steer (a slight change in the tire angle due to the longitudinal force of the suspension, lateral force) and suspension geometry (a change in the tire angle due to the suspension stroke), The alignment state can be detected with higher accuracy. In addition, it is desirable in terms of accuracy that these estimations are performed in a state where the estimated values are close to steady values (longitudinal force F _x ≈0, vertical load≈vehicle static load).

  In the state detection of the alignment based on the estimation of the toe angle as described above, the longitudinal force acting on the tire, the lateral force, etc. are directly detected, and based on these, an abnormality in the toe angle is detected. It can be said that the accuracy of abnormality detection is high.

(Fourth embodiment)
FIG. 9 is a block diagram showing the main configuration of the alignment state detection apparatus 40 according to the fourth embodiment, and FIG. 10 is a diagram for explaining the force acting on the tire. Parts having the same functions as those of the alignment state detection apparatus 10 according to the first embodiment are denoted by the same reference numerals. The alignment state detection device 40 is different from the alignment state detection device 10 of the first embodiment mainly in that it has a camber angle C estimation unit 41e. Same as device 10.

When the slip angle β is small and it can be assumed that the lateral force F _y is approximately proportional to the slip angle β, the lateral force F _y , using the proportional constant CP (cornering power) determined from the tire characteristics, The vertical force F _z , camber angle C, and slip angle have the relationship shown in the following mathematical formula 3. The camber angle C estimation unit 41e can use the lateral force F _y , the vertical force F _z , CP, and the slip angle β (β _f and β _m estimated as described above) detected by the tire force sensor 42. ) Is substituted into Formula 4 obtained by transforming Formula 3 to estimate the camber angle C.

In particular, in a stationary state or a straight traveling state, as shown in the front view of FIG. 10A, the vertical load G and the reaction force F _z are balanced for one (left) tire. The reaction force (vertical force) F _z can be decomposed into a normal force F _z ′ and a lateral force F _y of the tire, and the camber angle C can be estimated assuming that Equation 5 holds.

Furthermore, when the self-aligning torque SAT (or the torque around the vertical axis acting on the tire) can be detected, the camber angle can be estimated using this as follows. That is, the force generated by the slip angle β acts at a position shifted rearward from the center of the tire, and the pneumatic trail PT exists as shown in the top view of FIG. As a result, the SAT is increased so as to return the tire straight (SAT≈ (cast start rail + PT) × lateral force), but the lateral force F _yc generated by having the camber angle C acts on the center of the tire. Is relatively small (SAT≈caster rail × lateral force). For this reason, when the SAT is 0 while the vehicle is traveling, the slip angle β should be almost 0. If a lateral force is generated while the SAT is relatively small, it can be estimated that this lateral force is due to the ground camber of the tire, and at this time, the camber angle can be obtained assuming that Equation 6 holds.

  These camber angles C are often set to about ± 2 °, and these are stored in advance in the determination range memory 41c as a determination range or the like. In the alignment state determination unit 41b, when it is detected that the camber angle C estimated as in the above Equations 4 to 6 is not within the determination range, the driver is notified.

  In the state detection of the alignment based on the estimation of the camber angle as described above, the vertical force and lateral force acting on the tire are directly detected, and the camber angle abnormality is detected based on these, so that abnormality High detection accuracy.

  In the alignment state detection devices 30 and 40, abnormalities in the toe angle and camber angle were detected, respectively, but in addition, the values of elements representative of the alignment state such as the caster angle and the kingpin inclination angle were detected or estimated. Abnormality can be determined.

Explanatory drawing of the vehicle to which the alignment state detection apparatus 10 which concerns on 1st Embodiment was applied. Illustration of force acting on tire The block diagram which shows the main structures of the alignment state detection apparatus 10 The flowchart which shows the control procedure in the alignment state detection apparatus 10 Illustration of the judgment range and danger range regarding the resultant force of the longitudinal force and lateral force The block diagram of the alignment state detection apparatus 20 which concerns on 2nd Embodiment. The block diagram of the alignment state detection apparatus 30 which concerns on 3rd Embodiment. Top view of tire for explaining toe angle The block diagram of the alignment state detection apparatus 40 which concerns on 4th Embodiment. Front view and top view of the tire for explaining the acting force

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine 2 Automatic transmission 3a Center differential 3b Front differential 3c Rear differential 4 Axle 5 Tire 10, 20, 30, 40 Alignment state detection apparatus 11, 21, 31, 41 Microcomputer 11a, 21a, 31a, 41a Traveling state discrimination | determination part 11b , 21b, 31b, 41b Alignment state determination unit 11c, 21c, 31c, 41c Determination range memory 11d, 21d, 31d, 41d Determination result memory 12, 22, 32, 42 Tire force sensor 13, 23, 33, 43 State quantity sensor 14, 24, 34, 44 Alarm output unit 21e Longitudinal force value correction unit 31e Slip angle β _f estimation unit 31f Slip angle β _m calculation unit 31g Toe angle T calculation unit 41e Camber angle C estimation unit

Claims (6)

In an alignment state detection device for detecting the state of vehicle wheel alignment,
A tire force sensor that detects longitudinal force and lateral force acting on each tire;
When the vehicle is traveling straight and no driving force or braking force is applied to the vehicle, the resultant force of the longitudinal force and the lateral force detected by the tire force sensor for each tire is a predetermined force. An alignment state detection device comprising: an alignment state determination unit configured to determine a state of wheel alignment of the vehicle when having a direction or size outside the first determination range.   As a result of the determination by the alignment state determination unit, an alarm output unit for notifying the alignment state when any direction or magnitude of the resultant force for each tire is outside the first determination range is further provided. The alignment state detection apparatus according to claim 1, wherein: The alignment state determination unit includes a longitudinal force detected by the tire force sensor for each tire when the vehicle is traveling straight and a driving force and a braking force are not applied to the vehicle. Determining whether the resultant force of the lateral force has a direction and a magnitude of a predetermined second determination range;
The second determination range is a hollow region sandwiched between an outer locus that defines the first determination range and an inner locus that is concentric with the outer locus,
As a result of the determination by the alignment state determination unit, the direction and magnitude of the resultant force for each tire is stored when any direction and magnitude of the resultant force for each tire is in the second determination range. The alignment state detection apparatus according to claim 2, further comprising a determination result memory. In an alignment state detection device for detecting the state of vehicle wheel alignment,
A tire force sensor that detects longitudinal force and lateral force acting on each tire;
A longitudinal force value correcting unit that corrects the detected value of the longitudinal force so as to remove the estimated effect of the driving force and braking force on the vehicle from the detected value of the longitudinal force by the tire force sensor;
When the vehicle is traveling straight ahead, the resultant force of the longitudinal force corrected by the longitudinal force value correction unit and the lateral force detected by the tire force sensor for each tire is in a direction outside a predetermined determination range. Or an alignment state determination unit that determines a state of wheel alignment of the vehicle when it has a size. In an alignment state detection device for detecting the state of vehicle wheel alignment,
A tire force sensor that detects longitudinal force and lateral force acting on each tire;
A first slip angle estimator for estimating a first slip angle, which is a slip angle that has actually occurred, using detected values of longitudinal force and lateral force by the tire force sensor;
When it is assumed that the toe angle is 0 for each tire, a second slip angle, which is a slip angle estimated using the detected values of the vehicle-mounted sensor of the vehicle speed, lateral acceleration, yaw angular velocity, and steering angle, is calculated. A second slip angle calculation unit;
A toe angle calculator that calculates a toe angle from the first slip angle estimated by the first slip angle estimator and the second slip angle calculated by the second slip angle calculator;
An alignment state determination unit configured to determine a state of wheel alignment of the vehicle when the vehicle is traveling when the toe angle calculated by the toe angle calculation unit is a size outside a predetermined determination range; An alignment state detection apparatus comprising: In an alignment state detection device for detecting the state of vehicle wheel alignment,
A tire force sensor for detecting lateral force and vertical force acting on each tire;
A camber angle estimation unit that estimates a camber angle for each tire using the detected values of lateral force and vertical force by the tire force sensor;
An alignment state determining unit that determines a state of wheel alignment of the vehicle when the camber angle estimated by the camber angle estimating unit is out of a predetermined determination range. Detection device.

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