JP5549542B2 - Wheel angle adjustment device - Google Patents

Description

  The present invention relates to a wheel angle adjusting device provided in a vehicle.

  Vehicles are required to have stability during braking. On the other hand, for example, in Patent Document 1, a yaw moment generated by a difference in braking force applied to the left and right wheels or a steering of the front and rear wheels causes a vehicle deflection that occurs during braking due to a lateral shift of the center of gravity of the vehicle. The technique of reducing by this is disclosed. In this technology, the deceleration during straight braking of the vehicle is acquired, the yaw moment necessary for reducing the yaw moment due to the deviation of the center of gravity of the vehicle is obtained according to the acquired deceleration, and the obtained yaw moment is generated A braking force difference was given to the left and right wheels, or the front and rear wheels were steered.

  Further, in Patent Document 2, the braking force is distributed to each wheel so that the sum of the braking forces of the left front and rear wheels and the sum of the braking forces of the right front and rear wheels is equalized. A technique for avoiding the generation of a moment is disclosed.

JP 2008-037259 A JP 05-262213 A

  In the technique disclosed in Patent Document 1 described above, a configuration in which the braking force of the left and right wheels is made different, a configuration in which the front and rear wheels can be steered independently of the driver's steering, and a left and right generated according to the deceleration of the vehicle. A configuration for controlling the wheel braking force difference or the steering angle is necessary. Further, the technique disclosed in Patent Document 2 requires a configuration in which braking force is distributed to each wheel at a unique ratio. Therefore, the conventional technique has a problem that the configuration for realizing the method is complicated.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a technique for suppressing deflection that occurs during braking in a vehicle in which the position of the center of gravity is biased.

In order to solve the above-described problem, a wheel angle adjusting device according to an aspect of the present invention adjusts a toe angle of a wheel based on a position shift of the center of gravity where the center of gravity of the vehicle is shifted from the center position of the vehicle in the left-right direction of the vehicle A toe angle adjusting means is provided. This toe angle adjusting means adjusts the toe angle of the wheel on the side close to the center of gravity of the vehicle in the left and right direction of the left and right wheels so that it is in the toe-in direction from the toe angle of the far side wheel. According to this aspect, by adjusting the toe angle, it is possible to suppress the deflection that occurs during braking of the vehicle, and to reduce the moment in the yaw direction around the center of gravity that occurs during braking of the vehicle.

Toe angle adjusting means may adjust the average of the left front wheel and right front wheel toe angle, the average of the toe angle of the left rear wheel and right rear wheel so as to be substantially identical.

  The toe angle adjusting means steers the wheel according to the turning angle and the turning angle calculating means for calculating the turning angle for steering the wheel according to the operation amount of the steering handle operated by the driver. Steering means, misregistration amount calculating means for calculating the misalignment amount of the center of gravity, target thrust angle calculating means for calculating the target thrust angle based on the misalignment amount of the center of gravity, target thrust angle and steered angle calculating means And a turning angle adjusting means for calculating a new turning angle based on the turning angle calculated by the above. The steered means steers the wheel with a new steered angle. Accordingly, it is possible to more effectively suppress the deflection that occurs during braking.

  The toe angle adjusting means may include a load detecting means for detecting the ground contact load of the wheel and a lateral acceleration detecting means for detecting the lateral acceleration applied to the vehicle. The positional deviation amount calculation means may calculate the positional deviation amount of the center of gravity based on the ground load and the lateral acceleration. Thereby, even if the displacement amount of the center of gravity changes, the displacement amount of the center of gravity can be calculated accurately.

  The toe angle adjusting means may adjust the toe angle of each wheel every time it detects that the driver has boarded the vehicle. As a result, even when the position of the center of gravity of the vehicle changes depending on the number of passengers and luggage, it is possible to suppress deflection that occurs during braking.

  The toe angle adjusting means may include a torsion beam type suspension mechanism connected to the vehicle body while being connected to the wheels. The suspension mechanism includes a trailing arm, a bush connected to one end of the trailing arm, a shaft inserted into the shaft hole of the bush, a bracket that supports both ends of the shaft, and is attached to the vehicle body, and a shaft And an annular member to be inserted. The annular member is arranged on the right side of the bush when the position deviation of the center of gravity is on the right side from the center position of the vehicle, and is arranged on the left side of the bush when the position deviation of the center of gravity is on the left side from the center position of the vehicle. Also good. Thereby, a toe angle can be adjusted also with respect to a wheel provided with a torsion beam type suspension mechanism.

  ADVANTAGE OF THE INVENTION According to this invention, stability at the time of braking in the vehicle in which a gravity center position is biased can be improved by adjusting the toe angle.

It is a schematic diagram of a four-wheel vehicle according to an embodiment. It is a schematic diagram for demonstrating the mechanism in which a deflection | deviation generate | occur | produces at the time of the straight brake of a vehicle. It is a figure explaining the relationship between the gravity center G, the advancing direction S1 of a vehicle, and the toe angle of a wheel. It is a figure explaining the toe angle of each wheel of the vehicle concerning a 1st embodiment. It is a figure which shows typically the suspension mechanism which concerns on 2nd Embodiment. It is a figure which shows typically the suspension mechanism which concerns on 2nd Embodiment. It is a flowchart which shows the control which adjusts the toe angle of the wheel which concerns on 3rd Embodiment. It is a figure which shows the relationship between a lateral acceleration and a grounding load left-right difference.

  FIG. 1 is a schematic diagram of a four-wheel vehicle 10 according to the embodiment. The vehicle 10 includes a wheel angle adjusting device including at least a toe angle adjusting unit that adjusts a toe angle of a wheel.

  The vehicle 10 includes wheels including a left front wheel FL, a right front wheel FR, a left rear wheel RL, and a right rear wheel RR. Suspension mechanisms 14a and 14b (referred to as “suspension mechanism 14” unless otherwise distinguished) are provided between the vehicle body 12 of the right-hand drive vehicle 10 and the wheels FL, FR, RL, and RR. . By elastically supporting the wheel by the suspension mechanism 14, it is possible to prevent the impact of the wheel from being directly transmitted to the vehicle body 12. The suspension mechanism 14 generates a damping force between the sprung and unsprung parts of the vehicle.

  Load sensors 22a, 22b, 22c, and 22d (referred to as “load sensors 22” unless otherwise distinguished) for detecting the ground contact load of the wheels are incorporated in each wheel. The load sensor 22 may detect a lateral force applied to the vehicle 10 in addition to the ground load. The detection result of the load sensor 22 is sent to an electronic control device 100 (hereinafter referred to as “ECU 100”) provided in the vehicle body 12.

  A steering angle sensor 24 is provided on the steering handle 18 operated by the driver, and an operation amount of the steering handle is detected and transmitted to the ECU 100.

  The turning angle calculation unit of the ECU 100 calculates the turning angle according to the detection result of the steering angle sensor 24. The ECU 100 supplies a drive signal corresponding to the turning angle to the steering mechanism 20a for the front wheels and the steering mechanism 20b for the rear wheels (referred to as “the steering mechanism 20” unless otherwise distinguished). Steers the wheel according to the drive signal. The steering mechanism 20 can adjust the toe angle of the wheel.

  The center of gravity G of the vehicle 10 of the right-hand drive vehicle is on the right side of the center line C indicating the center position along the front and rear of the vehicle 10. If the vehicle structure is a symmetrical vehicle, the vehicle should not deflect during straight braking unless there is an external factor that deflects the vehicle. However, in reality, the mounting positions of various devices mounted on the vehicle are not symmetrical, and passengers and luggage are often loaded in a biased manner, so the vehicle weight distribution is rarely symmetrical. . That is, the center of gravity is shifted to the left or right from the center of the vehicle. An arrow S shown in FIG. 1 indicates the traveling direction of the vehicle 10 with respect to the wheel toe angle.

  FIG. 2 is a schematic diagram for explaining a mechanism in which deflection occurs during straight braking of the vehicle. In addition, the same code | symbol is attached | subjected about the same structure in the following drawings, and the description and illustration are abbreviate | omitted suitably. When equal braking torque is applied to the left and right wheels in a state where the center of gravity is shifted to the left or right, a moment in the yaw direction is generated around the center of gravity of the vehicle, so that the vehicle is deflected even during straight braking.

  FIG. 2 shows the vehicle 10 when the right-hand drive vehicle has one driver. In this case, the center of gravity G is located on the right side of the center line C of the vehicle body. Assume that the braking force applied to the left and right wheels is equal when the brake is applied (ie, D1 = D2> D3 = D4). Since the moment in the yaw direction around the center of gravity is represented by the product of the distance of each wheel FL, FR, RL, RR from the center of gravity and the braking force, when the center of gravity G is to the right, the center of gravity G is shown in the figure. Counterclockwise moment M is generated. Since the distance between the left front wheel FL and the left rear wheel RL and the center of gravity G is longer than the distance between the right front wheel FR and the right rear wheel RR and the center of gravity G, the moment around the center of gravity generated by the left front wheel FL and the left rear wheel RL is large. Because it becomes. Therefore, the vehicle body is deflected in the left direction BL in the figure.

  In the embodiment, in order to suppress this deflection, a toe angle adjusting unit that adjusts the toe angle of the wheel based on the positional deviation of the center of gravity G in which the center of gravity G of the vehicle 10 is shifted in the left-right direction from the center position of the vehicle 10 is provided. . The left-right direction of the vehicle 10 is, for example, a direction parallel to a straight line connecting the center of the left front wheel FL and the center of the right front wheel FR. Note that the toe angle in the embodiment will be described with the counterclockwise direction as positive and the clockwise direction as negative with reference to the front-rear direction of the vehicle 10 orthogonal to the left-right direction. Toe-out is a state where the front end of the wheel is located outside the center of the wheel, and toe-in is a state where the front end of the wheel is located inside the center of the wheel. Toe-in is positive on the right wheel, and toe-out is positive on the left wheel.

FIG. 3 is a diagram for explaining the relationship among the center of gravity G, the vehicle traveling direction S1, and the toe angle of the wheels. An angle between the traveling direction S1 and the center line C of the vehicle 10 (hereinafter referred to as a thrust angle) is θ1. Point P is the midpoint of left front wheel FL and right front wheel FR. The thrust angle is positive on the left side (counterclockwise when viewed from above the vehicle) and negative on the right side (clockwise when viewed from above the vehicle) with respect to the center line C. The traveling direction S1 of the vehicle 10 shown in FIG. 3 is determined by the toe angle of each wheel. That is, the toe angle adjustment unit sets the positive thrust angle θ1 by adjusting the toe angle of each wheel.
When the vehicle 10 is traveling straight, the thrust angle θ1 is expressed by the following equation.
θ1 = (QFR + QFL) / 2 = (QRR + QRL) / 2

  Here, the moment around the center of gravity can be reduced by changing the toe angles of the left front wheel FL and the left rear wheel RL to the toe-out side. Further, the moment around the center of gravity can be increased by changing the toe angles of the right front wheel FR and the right rear wheel RR to the toe-in side. The left front wheel FL may be changed to the toe-out side, the right rear wheel RR may be changed to the toe-in side, the right front wheel FR may be changed to the toe-in side, and the left rear wheel RL may be changed to the toe-out side. Any change in toe angle reduces the moment around the center of gravity when the center of gravity G is shifted to the right. In addition, since a braking force greater than that of the rear wheels is applied to the front wheels, the degree of contribution to the moment around the center of gravity of the front wheels is greater than that of the rear wheels. Thus, when the toe angle of the left front wheel FL and the left rear wheel RL is changed to the toe-out side, and when the toe angle of the right front wheel FR and the right rear wheel RR is changed to the toe-in side, the thrust angle is positive. And the deflection at the time of braking of the vehicle 10 in which the center of gravity G is shifted to the right side can be suppressed.

The closer the center of gravity G is to the center line C, the smaller the moment around the center of gravity. Let L be the distance between the front and rear of the wheel, for example, the distance between the center of the left front wheel FL and the center of the left rear wheel RL. Further, the ratio of the braking force applied to the vehicle 10 applied to the front wheels is referred to as Bf and is referred to as the front wheel braking force ratio Bf. Further, a ratio of the ground load of the vehicle 10 applied to the front wheels is Lf, and is referred to as a front wheel load ratio Lf. At this time, if the toe angle of the wheel is adjusted so as to be the thrust angle θ1, the center of gravity G is brought closer to the center line C by the distance shown in the following equation (1).
sinθ1 · L (Bf−Lf) (1)
Since (Bf−Lf) is a difference in distribution between the front wheels and the rear wheels, the same value is obtained even if calculated with the rear wheels instead of the front wheels. If the distance shown in equation (1) is equal to the amount of displacement of the center of gravity G, the moment in the yaw direction around the center of gravity can be canceled.
A method for adjusting the toe angle of the wheel to suppress the deflection at the time of braking will be specifically described.

(First embodiment)
FIG. 4 is a diagram illustrating the toe angle of each wheel of the vehicle 10 according to the first embodiment. In the first embodiment, the toe angle adjusting unit causes the average value of the toe angles of the left front wheel FL and the right front wheel FR to be substantially the same as the average value of the toe angles of the left rear wheel RL and the right rear wheel RR. Adjust to. In addition, the toe angle adjusting unit, when the center of gravity G is shifted in the left-right direction from the center position C of the vehicle 10, the left front wheel FL and the left rear wheel RL (left wheel), or the right front wheel FR and the right rear wheel RR (right Wheel), the wheel front end closer to the center of gravity G in the left-right direction is adjusted to be closer to the center position C than the far side. That is, the toe angle of the wheel closer to the center of gravity G is adjusted from the far side to the toe in side.

  The toe angle adjusting unit according to the first embodiment may adjust the toe angle in advance before shipment of the vehicle 10 as initial alignment. When the displacement of the center of gravity G occurs at the time of shipment of the vehicle, it is possible to cope with the deflection at the time of braking in advance. At this time, the center of gravity G of the vehicle 10 may be a position in a state where one driver is on the vehicle 10.

  The toe angle adjustment unit may include the ECU 100 and the steering mechanism 20, and adjusts the toe angle of the wheels by the ECU 100 and the steering mechanism 20. Further, the toe angle adjusting unit may adjust the toe angle using other conventional techniques, for example, the technique for adjusting the toe angle of a wheel described in Japanese Patent Application Laid-Open No. 2010-173577 and Japanese Patent Application Laid-Open No. 2007-331626. .

  For example, when the center of gravity G is shifted to the right side from the center position C of the vehicle 10 as shown in FIG. 4, the toe angle adjusting unit has a smaller toe-out angle t2 of the right front wheel FR than a toe-out angle t1 of the left front wheel FL. The toe-in angle t4 of the right rear wheel RR is set to be larger than the toe-in angle t3 of the left rear wheel RL.

  In the aspect shown in FIG. 4, since the toe angles of the right front wheel FR and the right rear wheel RR are adjusted to the toe-in side from the left wheel, the traveling direction S2 determined by the toe angle of each wheel adjusted by the toe angle adjusting unit is It faces to the left and the thrust angle is θ2. As a result, the moments around the center of gravity generated during braking act so as to cancel each other, so that deflection during braking can be suppressed. The toe angle of each wheel that is adjusted to be the thrust angle θ2 may be a predetermined numerical value, and may be held in the ECU 100 in advance.

  The toe angle adjusting unit according to the first embodiment may adjust the toe angle every time the driver gets on the vehicle 10. For example, the ECU 100 may detect that the driver has boarded the vehicle 10 when the ignition switch is turned on. When detecting that the driver gets on the vehicle 10, the ECU 100 controls the steering mechanism 20 to adjust the toe angle of the wheels so that the thrust angle θ2 is obtained. Also according to this aspect, the deflection at the time of braking of the vehicle 10 can be suppressed.

(Second Embodiment)
FIG. 5 is a diagram schematically showing the suspension mechanism 14b according to the second embodiment. FIG. 5A is a view of the rear portion of the vehicle 10 as viewed from above, and FIG. 5B is a cross-sectional view of the left wheel bush mechanism 30a. The suspension mechanism 14b is a torsion beam type in which one end is attached to the vehicle body 12 and the other end is attached to the rear wheel. The vehicle 10 shown in FIG. 5 is a right steering wheel, and the center of gravity G is also shifted rightward from the center position C.

  The suspension mechanism 14 includes a left wheel trailing arm 28a, a right wheel trailing arm 28b, a torsion beam 26, a left wheel bush mechanism 30a, and a right wheel bush mechanism 30b as main components. Hereinafter, the left wheel trailing arm 28a and the right wheel trailing arm 28b are referred to as the trailing arm 28, and the left wheel bush mechanism 30a and the right wheel bush mechanism 30b are referred to as the bush mechanism 30 as appropriate.

  The trailing arm 28 is a pipe-like member, and is arranged with the longitudinal direction of the vehicle. A left wheel bushing mechanism 30a is attached to the end of the left wheel trailing arm 28a on the front side of the vehicle, and the left wheel trailing arm 28a is swingable and elastic to the vehicle body side via the left wheel bushing mechanism 30a. Connected. Similarly, a right wheel bushing mechanism 30b is attached to an end of the right wheel trailing arm 28b on the vehicle front side, and the right wheel trailing arm 28b is moved to the vehicle body side via the right wheel bushing mechanism 30b. It is elastically connected.

  The left wheel trailing arm 28a is connected to the left rear wheel RL via a connecting member (not shown), and the right wheel trailing arm 28b is connected to the right rear wheel RR via a connecting member (not shown). The A shock absorber (not shown) connected to the vehicle body 12 may be attached to the trailing arm 28.

  As shown in FIG. 5B, the left wheel bush mechanism 30 a includes a bracket 32, a bush 34, a shaft portion 36, an inner cylinder portion 38, and an annular member 40. The outer surface of the bracket 32 is attached to the vehicle body 12. A shaft hole is formed in the first plane 32 a and the second plane 32 b of the bracket 32.

  The shaft portion 36 is formed in a rod shape, and both ends thereof are inserted into the shaft holes of the bracket 32 and supported by the bracket 32. The inner cylinder portion 38 is formed in a cylindrical shape, is inserted into the shaft portion 36, and is accommodated in the bracket 32. The axial length of the inner cylinder portion 38 is smaller than the distance between the first plane 32a and the second plane 32b.

  The bush 34 is formed in a cylindrical shape, and an axial hole is formed in the center. The bush 34 has elasticity, and the side surface of the bush 34 is connected to one end of the trailing arm 28. An inner cylindrical portion 38 and a shaft portion 36 are inserted into the shaft hole of the bush 34 and accommodated in the bracket 32. The shaft part 36 and the inner cylinder part 38 are relatively rotatable. The axial length of the bush 34 is smaller than the distance between the first plane 32a and the second plane 32b.

  The annular member 40 has a disk shape like a so-called washer, and a shaft hole is formed at the center. A shaft portion 36 is inserted into the shaft hole of the annular member 40. The bush 34 and the inner cylinder portion 38 are disposed on the left side of the annular member 40, and the second plane 32 b of the bracket 32 is disposed on the right side of the annular member 40. The annular member 40 is supported by being sandwiched by one end of the inner cylinder portion 38 from the left side and the second plane 32b from the right side. The right wheel bush mechanism 30b is similar to the left wheel bush mechanism 30a.

  In the vehicle 10, the shift of the center of gravity G is on the right side of the center line C. The annular member 40 is disposed on the right side of the bush mechanism 30. Thereby, both ends of the trailing arm 28 are shifted to the left as compared with the case where the annular member 40 is not provided, the toe angle of the left rear wheel RL becomes the toe-out direction, and the toe angle of the right rear wheel RR becomes the toe-in direction. Therefore, the thrust angle in the traveling direction S3 becomes θ3 on the left side, and acts to reduce the moment in the rotational direction generated during braking, so that deflection during braking can be suppressed. Thus, the suspension mechanism 14 having the annular member 40 can function as a toe angle adjusting unit with a simple configuration. The left rear wheel RL is not necessarily toe-out, and the toe-in of the left rear wheel RL only needs to be smaller than the toe-in of the right rear wheel RR.

  FIG. 6 is a diagram schematically illustrating the suspension mechanism 14b according to the second embodiment. FIG. 6A is a top view of the rear portion of the vehicle 10, and FIG. 6B is a cross-sectional view of the left wheel bush mechanism 30c. A vehicle 10 shown in FIG. 6 is a left-hand drive vehicle, and the position of the center of gravity G is different from that shown in FIG.

  In the vehicle 10, the shift of the center of gravity G is on the left side of the center line C. The annular member 40 is disposed on the left side of the bush mechanism 30. The bush 34 and the inner cylinder portion 38 are disposed on the right side of the annular member 40, and the first plane 32 a of the bracket 32 is disposed on the left side of the annular member 40. The annular member 40 is supported by being sandwiched by one end of the inner cylinder portion 38 from the right side and the first plane 32a from the left side. The right wheel bush mechanism 30d is the same as the left wheel bush mechanism 30c.

  Thereby, both ends of the trailing arm 28 are shifted to the right as compared with the case where the annular member 40 is not provided, the toe angle of the left rear wheel RL becomes the toe-in direction, and the toe angle of the right rear wheel RR becomes the toe-out direction. Therefore, the thrust angle in the traveling direction S4 becomes θ4 on the right side, and acts to reduce the moment in the rotational direction generated during braking, so that deflection during braking can be suppressed. Thus, the annular member 40 can function as a toe angle adjusting unit with a simple configuration.

  In the second embodiment, the toe angle of the wheel can be adjusted in advance by changing the position where the annular member 40 is attached based on whether the displacement of the center of gravity G is on the right side or the left side. As shown in FIGS. 5 and 6, both the right handle and the left handle can be handled by using the same member. Further, the toe angle can be adjusted in the bush mechanism 30 of the suspension mechanism 14 without the steering mechanism 20b for adjusting the toe angle.

  It is also possible to combine the first embodiment and the second embodiment. For example, the ECU 100 previously holds the thrust angle θ3 adjusted by the annular member 40 or the toe angle of the rear wheel, and adjusts the toe angle of each wheel based on the angle obtained by subtracting the thrust angle θ3 from the thrust angle θ2.

(Third embodiment)
The vehicle 10 according to the third embodiment includes a front wheel steering mechanism 20a and a rear wheel steering mechanism 20b as shown in FIG. The ECU 100 controls the toe angle of each wheel based on the center of gravity G of the vehicle 10 by controlling the driving of the steering mechanism 20. At least the ECU 100 and the steering mechanism 20 function as a toe angle adjusting unit.

  The ECU 100 calculates the positional deviation of the center of gravity G of the vehicle in the left-right direction as follows. The ECU 100 detects the ground load of the left front wheel FL and the left rear wheel RL detected by the load sensors 22a and 22c that detect the ground load of the left front wheel FL and the left rear wheel RL, and contacts the right front wheel FR and the right rear wheel RR. The ground load Wr of the right front wheel FR and the right rear wheel RR detected by the load sensors 22b and 22d for detecting the load is acquired. Here, a difference may occur in the ground load of each wheel when the center of gravity G of the vehicle 10 is shifted from the center line C of the vehicle 10. In addition, a difference may occur in the ground contact load of each wheel due to load movement accompanying a road surface inclination or turning.

  Therefore, the ECU 100 acquires the lateral force applied to the vehicle 10 from the detection result of the load sensor 22. When the lateral force is divided by the mass (total load) of the vehicle 10, a lateral acceleration α is obtained. Note that lateral acceleration detection means other than the load sensor 22 may be used. For example, a lateral acceleration sensor (not shown) is provided on the vehicle body 12, and the lateral acceleration α applied to the vehicle 10 is acquired by the lateral acceleration sensor. Then, the ECU 100 extracts the ground load difference based on the displacement of the center of gravity G by subtracting the ground load difference based on the road surface inclination or turning estimated from the lateral acceleration α from the ground load difference (Wr−Wl) between the left and right wheels. To do. The ECU 100 obtains the position of the center of gravity G from the ground contact load difference based on the displacement of the center of gravity G, calculates the target thrust angle θ from the position of the center of gravity G, and sets the target thrust angle θ to each wheel at that time. In addition to the steered angle, a new steered angle is calculated, and the steered mechanism 20 is controlled so as to obtain a new steered angle. The target thrust angle θ is a target thrust angle for suppressing the deflection at the time of braking caused by the displacement of the center of gravity G, and is relative to the vehicle center line in the traveling direction of the vehicle according to the toe angle of each wheel. An angle.

  FIG. 7 is a flowchart showing control for adjusting the toe angle of the wheel according to the third embodiment. FIG. 8 is a diagram illustrating the relationship between the lateral acceleration and the difference between the left and right contact loads. The control flow shown in FIG. 7 may be continuously executed at predetermined time intervals when the ignition is turned on, for example. Further, it may be executed every time it is detected that the driver has boarded the vehicle. For example, when it is detected that the door of the driver's seat of the vehicle 10 is closed and the ignition is on, the driver is assumed to have boarded. Is done.

  First, the ECU 100 deletes the ground load Wr of the right front wheel FR and the right rear wheel RR, the ground load Wl of the left front wheel FL and the left rear wheel RL, and the lateral acceleration α stored in the ROM (S101).

  Subsequently, the sensor information acquisition unit of the ECU 100 repeatedly samples the ground load Wr of the right front wheel FR and the right rear wheel RR, the ground load Wl of the left front wheel FL and the left rear wheel RL, and the lateral acceleration α at predetermined intervals. Store in the ROM (S102). Since the ground loads Wr, Wl and the lateral acceleration α fluctuate due to the influence of road surface undulations, sampling is performed by taking a time average or removing a fluctuation component to some extent with a low-pass filter. After a predetermined time has elapsed, as shown in FIG. 8, the positional deviation amount calculation unit of the ECU 100 calculates the ground load difference Wr−Wl between the left and right wheels and the regression line R of the lateral acceleration α from the stored information by the least square method or the like. The intercept ΔW is calculated (S103).

The regression line R can be expressed by the following equation (2), where the slope is I and the y-intercept is ΔW. Note that the y-axis is the ground load left-right difference (Wr−Wl), and the x-axis is the lateral acceleration α.
y = I · α + ΔW (2)

Since the y intercept ΔW of the regression line R is a contact load difference when the lateral acceleration α is 0, it corresponds to a contact load difference between the left and right wheels based on the shift of the center of gravity position G. Accordingly, if the tread of the right wheel and the left wheel is T, the positional deviation amount Gd of the center of gravity G from the center line (bias of the center of gravity in the left-right direction) can be expressed by the following equation (3). The position of the center of gravity G is determined by the positional deviation amount Gd.
Gd = ΔW · T / 2 (Wr + Wl) (3)

  The positional deviation amount calculation means of the ECU 100 calculates the positional deviation amount Gd of the center of gravity G based on the above equation (3), and the target thrust angle calculation means of the ECU 100 calculates the vehicle based on the calculated positional deviation amount Gd. A target thrust angle θ that is a target of progress is calculated (S104).

The above formula (1) represents a distance for reducing the displacement of the center of gravity G while the vehicle is traveling. If this distance is equal to the displacement amount Gd of the center of gravity G, the moment around the center of gravity due to the displacement amount Gd of the center of gravity G is expressed. Can be canceled. Therefore, the following formula (4) is expressed by formula (1) and formula (3).
sinθ · L (Bf−Lf) = ΔW · T / 2 (Wr + Wl) (4)

Since the target thrust angle θ is as small as several degrees, it can be approximated as sin θ≈θ. Therefore, the target thrust angle θ can be expressed by the following equation (5).
θ≈ΔW · T / {2 (Wr + Wl) · L (Bf−Lf)} (5)
The target thrust angle calculation means of the ECU 100 calculates the target thrust angle θ based on the positional deviation amount Gd.

  The turning angle adjusting unit of the ECU 100 adjusts the steering angle of each wheel calculated by the turning angle calculating unit so as to add the target thrust angle θ, and the turning control unit of the ECU 100 sets the target thrust angle θ. The steering mechanism 20 is controlled based on the added steering angle of each wheel (S105). Thereby, ECU100 can suppress the deflection | deviation at the time of braking based on the positional offset amount Gd of the gravity center G by repeating the above process.

  Note that the ECU 100 may regard the threshold as the target thrust angle when the target thrust angle θ exceeds the threshold. The threshold value is set to such a value that the driver does not feel uncomfortable driving by adding the target thrust angle θ, and is determined by experiments or the like.

  Further, if the steering angle of the steering mechanism 20 exceeds the maximum movable range, no further control is possible. Therefore, when the turning angle of each wheel to which the target thrust angle θ is added exceeds the maximum movable angle of the turning angle of the turning mechanism 20, the ECU 100 turns the maximum moving angle of the turning mechanism 20 to the turning of each wheel. Control as a corner.

  Note that the ECU 100 uses the map in which the ground load difference ΔW between the left and right wheels and the positional deviation amount Gd of the center of gravity G are stored in advance in the ROM, for example, so that the deviation amount Gd is calculated from the ground load difference ΔW. You may get it.

  The present invention is not limited to the above-described embodiments, and it is possible to combine the embodiments and modifications, and to make various modifications such as design changes based on the knowledge of those skilled in the art. Such combined or modified embodiments are also included in the scope of the present invention. A new embodiment generated by the combination of the above-described embodiments and modifications has the effects of the combined embodiments and modifications.

  In the third embodiment, the ECU 100 adjusts the toe angle only during braking. Here, since the deflection during braking increases when the vehicle speed is high, the ECU 100 may adjust the toe angle when the vehicle speed is equal to or higher than a predetermined speed. Thereby, deflection can be effectively suppressed.

  FL left front wheel, FR right front wheel, RL left rear wheel, RR right rear wheel, 10 vehicle, 12 vehicle body, 14a, 14b suspension mechanism, 18 steering handle, 20a, 20b steering mechanism, 22a, 22b, 22c, 22d load sensor , 24 Steering angle sensor, 26 Torsion beam, 28a, 28b Trailing arm, 30a, 30b Bush mechanism, 32 Bracket, 34 Bush, 36 Shaft, 38 Inner tube, 40 Annular member, 100 ECU.

Claims (6)

A toe angle adjusting means for adjusting a toe angle of a wheel based on a position shift of the center of gravity, wherein the center of gravity of the vehicle is shifted in a lateral direction of the vehicle from a center position of the vehicle;
The toe angle adjusting means adjusts the toe angle of a wheel closer to the center of gravity of the vehicle in the left-right direction of the vehicle among the left and right wheels so that the toe-in direction is closer to the toe angle of the far wheel. Wheel angle adjustment device. The toe angle adjusting means, claims, characterized the average of the left front wheel and right front wheel toe angle, a Rukoto tone pollock so as to be substantially equal to the average of the toe angle of the left rear wheel and the right rear wheel 1. The wheel angle adjusting device according to 1. The toe angle adjusting means includes
A turning angle calculating means for calculating a turning angle for steering the wheel according to the operation amount of the steering wheel operated by the driver;
Steering means for steering the wheels according to the steered angle;
A displacement amount calculation means for calculating a displacement amount of the center of gravity;
Target thrust angle calculating means for calculating a target thrust angle based on the amount of displacement of the center of gravity;
Turning angle adjusting means for calculating a new turning angle based on the target thrust angle and the turning angle calculated by the turning angle calculation means,
The wheel angle adjusting device according to claim 1 or 2, wherein the steering means steers the wheel at the new turning angle. The toe angle adjusting means includes
Load detecting means for detecting the ground contact load of the wheel;
Lateral acceleration detection means for detecting lateral acceleration applied to the vehicle,
The wheel angle adjustment device according to claim 3, wherein the positional deviation amount calculating means calculates the positional deviation amount of the center of gravity based on the ground load and the lateral acceleration. The wheel angle adjusting device according to any one of claims 1 to 4, wherein the toe angle adjusting means adjusts a toe angle of each wheel every time it is detected that the driver gets on the vehicle. The toe angle adjusting means includes a torsion beam type suspension mechanism that is connected to a vehicle body with wheels connected thereto,
The suspension mechanism is
A trailing arm,
A bush connected to one end of the trailing arm;
A shaft portion inserted into the shaft hole of the bush;
A bracket that supports both ends of the shaft and is attached to the vehicle body;
An annular member into which the shaft portion is inserted,
The annular member is disposed on the right side of the bush when the displacement of the center of gravity is on the right side from the center position of the vehicle, and the annular member is disposed on the right side of the bush when the position shift of the center of gravity is on the left side with respect to the center position of the vehicle. The wheel angle adjusting device according to any one of claims 1 to 5, wherein the wheel angle adjusting device is arranged on the left side.

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