JPH03132416A - Wheel camber angle control device - Google Patents

Abstract

PURPOSE:To maintain the atability of a vehicle by controlling the camber angle of each wheel in such a way as to change the camber thrust force of the wheel in the direction of reducing the behavioral change of the vehicle at the time of detecting the cross wind acting upon a body. CONSTITUTION:Bilateral front and rear wheels are respectively provided with actuators 2, 4, 6, 8 formed of hydraulic cylinders, and the upper end position of a suspension strut is displaced in the lateral direction of a vehicle so as to adjust the camber angle of each wheel W by expanding/contracting the actuators 2-8. The supply/discharge of oil to the actuators 2-8 is controlled by controlled by control valves 10-18, and the control valves 10-18 are controlled by a controller 32. Regarding this control, when a wind pressure sensor 36 detects the cross wind acting upon a body, the camber angle of the wheel is controlled in such a way as to change the camber thrust force of each wheel in the direction of reducing the behavioral change of a vehicle caused by the cross wind.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a wheel camber angle control device, and more particularly to a device for automatically controlling the wheel camber angle of an automobile depending on the driving conditions.

[Conventional technology]

Conventionally, as mentioned above, as a device for automatically controlling the camber angle of the wheel according to the driving situation, for example, Japanese Patent Laid-Open No. 57-53
No. 613 or JP-A-62. The one shown in No.-125952 is known.

[Problem to be solved by the invention]

However, none of the above conventional technologies controls the camber angle in response to changes in vehicle behavior caused by crosswinds while driving, and therefore cannot prevent changes in behavior that occur when the vehicle is hit by crosswinds while driving. There wasn't.

For this reason, in the past, in order to prevent the vehicle's behavior from becoming unstable due to crosswinds, the suspension itself or its installation points were devised, or the body shape was devised to prevent vehicle design constraints. I often received it.

[Means to solve the problem]

The present invention has been devised in view of the above, and includes an actuator that adjusts the camber angle of a wheel, a wind pressure sensor that detects a crosswind acting on the vehicle body, and when the wind pressure sensor detects that the crosswind has acted on the vehicle body. and control means for driving the actuator to control the camber angle of the wheel so that the canvas thrust force of the wheel changes in a direction that reduces changes in vehicle behavior caused by the crosswind. This is a wheel camber angle control device.

[Effect]

According to the present invention, when a crosswind acts on the vehicle while driving, the wind pressure sensor detects it, and the control means changes the canvas thrust force of the wheel in a direction that reduces changes in vehicle behavior caused by the crosswind. The actuator is driven to control the camber angle of the wheel so that the camber angle of the wheel is controlled.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 shows an embodiment of the present invention, in which reference numeral 2 is an actuator for adjusting the camber angle of the left front wheel, 4 is an actuator for adjusting the camber angle of the right front wheel, and 6 is an actuator for adjusting the camber angle of the left rear wheel. 8 is an actuator that adjusts the camber angle of the right rear wheel. These actuators 2 to 8 are constituted by hydraulic cylinders,
Specifically, the suspension is provided as shown in FIG. 2, for example. In other words, although Figure 2 is a front view of the car, the strut S of the strut type suspension
An actuator A is interposed between the upper end and the vehicle body F, and by extending or contracting the actuator, the upper end position of the strut S is displaced in the vehicle width direction, thereby adjusting the camber angle θ of each wheel W. It is possible.

Each actuator 2. 4. 6 and 8 are driven by electromagnetic control valves 10, 12, 14 and 16, respectively. Each control valve 10.12.14 and 16 is connected to a pump 20 via a supply line 18 and to an oil reservoir 2 via a discharge line 22.
Connected to 4. The pump 20 is driven by an engine (not shown) or the like to suck oil in the oil reservoir 24 and discharge it to the supply path 18 . An accu-12 regulator 26 is connected to the supply line 18, and the supply line 18 is also connected to a reservoir 24 via an IJ-F valve 28, thereby maintaining the supply line 18 at a set pressure.

Each of the control valves 10, 12, 14 and 16 is set to a first position in which supply and discharge of oil to each actuator 2 to 8 is prohibited and locked, and a first position in which each actuator 2 to 8 is locked by each control signal from the drive circuit 30. A second position where oil is supplied and discharged in the direction of extension (positive camber direction) and a third position where oil is supplied and discharged in the direction in which each actuator 2 to 8 contracts (negative camber direction) can be taken individually.

32 is a controller that outputs a control signal to the drive circuit 30; the controller 32 inputs output signals from each sensor described later, performs predetermined program processing, and outputs a control signal to the drive circuit 30. . For this reason, the controller 32 includes a ROM 34 that stores the above-mentioned predetermined program, an input circuit (not shown) for inputting the output signals of each sensor, a CPU RAM and an output for executing calculations and processes according to the program. circuits and interfaces between these elements.

The above-mentioned sensors include a well-known wind pressure sensor 36 that detects the wind pressure that the vehicle receives from the side and its direction;
A steering sensor 38 that detects the steering angle of a steering wheel (not shown), a vehicle speed sensor 40 that detects vehicle speed, a displacement sensor 42 that detects the stroke position of the left front wheel actuator 2, and a displacement sensor that detects the stroke position of the right front wheel actuator 4. 44, left rear wheel actuator 6
A displacement sensor 46 that detects the stroke position of the rear right wheel, and a displacement sensor 48 that detects the displacement of the actuator 8 of the right rear wheel are provided.

Next, the processing executed by the controller 32 will be explained according to the flowchart shown in FIG.

The controller 32 executes the program processing according to the flowchart shown in FIG. 3 when the engine switch (not shown) is turned on. First, in step S1, initialization is performed, that is, a predetermined memory area necessary for program processing is cleared to zero or set to an initial value. Next, in step S2, the outputs of the sensors 36 to 48 are read and stored in a predetermined memory area. Next, proceed to step S3, and step S2
It is determined whether the stored vehicle speed is equal to or higher than a set vehicle speed (for example, 3 km/h). If “NO” in step S3,
Proceeding to step S4, a reference value for each actuator suitable for normal straight-ahead travel is set as a target value for determining the target stroke position of each actuator 2-8.

If rYESJ is determined in step S3, the process proceeds to step S5, and the absolute value of the steering angle δ stored in step S2 is the set steering angle δ. (for example, 30 deg) or less. If rNO:l in step S5, step S
Proceed to step 4.

If rYEsJ is determined in step S5, the process proceeds to step S6, and it is determined whether the wind pressure P stored in step S2 is greater than or equal to the set wind pressure Po. Note that this set wind pressure Po is set to a value at which the vehicle begins to be affected by crosswinds.

If rYEsJ is determined in step S6, the process proceeds to step S7, where target values for each actuator 2 to 8 are set with reference to a map as described later.

Next, setting of the target value with reference to this map will be specifically explained. Note that here, as shown in Figure 4,
Center point M of the lateral pressure exerted on the vehicle by crosswinds
A description will be given of a case of a type of vehicle in which the vehicle is located ahead of the center of gravity G of the vehicle (in the direction of arrow F).

First, based on the wind pressure and wind direction stored in step S2,
The target camber angle of each wheel is determined by referring to the wind pressure-camber angle map shown in FIG. 5, and the vehicle speed-correction integer map shown in FIG. 6 is determined based on the vehicle speed stored in step S2. A correction coefficient is determined, and the target camber angle is corrected by multiplying the obtained target camber angle by the above correction coefficient with reference to the wind pressure-camber angle map, and then the target camber angle is adjusted according to the corrected target camber angle of each wheel. Each actuator 2 to 8
Set target values for

When the process of step S7 is finished in this way, or when the process of step S4 is finished, the process proceeds to step S8, where a control signal is output to the drive circuit 30 so that the stroke position of each actuator matches each target value. . Specifically, first, it is determined whether the stroke positions of the actuators 2 to 8 stored in step S2 match the target values for each wheel set in step S7 or S4. Then, among the actuators 2 to 8, the actuator that matches the target value is driven to lock that actuator, that is, to control the corresponding control valve among the control valves 10 to 16 to the first position. A control signal is output to the circuit 30. Also, actuator 2~
For actuators among the control valves 10 to 16 that do not match the target value, a control signal is output to the drive circuit 30 to control the corresponding control valve among the control valves 10 to 16 so that the stroke position of the actuator does not match the target value. . In other words, if the actuator needs to be extended, the corresponding control valve is controlled to the second position, and if the actuator needs to be shortened, the corresponding control valve is controlled to the third position. A signal is output to the drive circuit 30.

After completing the process of step S8, step S8 is again performed.
Return to step 2 and read the output signals of each sensor. By repeating the processes from steps S2 to 88 in this way, the stroke positions of each actuator 2 to 8 are finally controlled to each target value. Note that one cycle of repeating the processing of steps 82 to 8 is approximately several ms, although it depends on the capabilities of the CPU, etc. in the controller 32.

According to the embodiment configured in this way, for example, if the vehicle receives a crosswind from the left side while the vehicle is running with the steering wheel (not shown) maintained at its approximately neutral position (straight ahead position), the Due to its characteristics, the vehicle originally exhibits a behavior of trying to turn to the right, but the camber angle of each wheel is controlled by the control signal from the controller 32, and the camber angle of the left wheel of the front wheels is positively adjusted to the camber angle of the right wheel. In the rear wheels, the camber angle of the left wheel is controlled negatively and the camber angle of the right wheel is controlled positively. As a result, the canvas thrust force of each wheel acts in a direction that cancels out the above-mentioned behavior of the vehicle attempting to turn to the right, and the straight-line stability of the vehicle during crosswinds can be significantly improved.

In the embodiment described above, when the vehicle speed V is extremely low, less than the set vehicle speed Vo, the reference value is set as the target value of each actuator 2 to 8, and the camber angle control is not performed. This is done in consideration of the fact that if you stop with the camber angle control in place due to a crosswind, the camber angle of each stopped wheel will be unnatural and unbalanced force will act on the tires of each wheel for a long time. Therefore, when the vehicle stops, the camber angle of each wheel can always be returned to the reference camber angle.

Further, in the above embodiment, the absolute value of the steering angle of the steering wheel is the set steering angle δ. (that is, when the vehicle is not traveling straight), the target value of each actuator 2 to 8 is set to the reference value, and the camber angle control is not performed. This is because when the steering wheel is actually turned and the car is turning, the camber angle control is executed taking only the crosswind into account, even though the crosswind due to the turning itself is acting on the car body. This was done in consideration of the fact that if this happens, the steering characteristics (understeer characteristics or oversteer characteristics) will change significantly and the steering feeling for the driver will deteriorate.Therefore, this prevents the deterioration of the steering feeling when turning. can.

Further, in the embodiment described above, when the wind pressure P is lower than the set wind pressure PO, the reference value is set as the target value of each actuator 2 to 8, and the camber angle control is not performed. Strictly speaking, even a weak crosswind has an effect on the behavior of the vehicle while it is running, so it would be better to implement camber angle control, but if the crosswind is small enough that the driver does not feel it has much of a negative effect, On the other hand, if the camber angle control is executed each time, not only will the loss of labor and energy increase, but also the durability of each control valve and actuator will deteriorate. can be resolved. In addition, in the above embodiment, the target camber angle 1 2 is corrected in step S8 by multiplying it by a correction coefficient obtained from the vehicle speed-correction coefficient map shown in FIG. This is because it takes into account that the influence on behavior changes caused by Therefore, optimal camber angle control can be executed depending on the vehicle speed.

In addition, the reference camber angle of each wheel in the above example is set to the optimum value for normal driving, such as setting the front wheels slightly positive and the rear wheels slightly negative, or vice versa, depending on the characteristics of the vehicle. It is set to . Furthermore, the wind pressure camber angle map shown in FIG. 5 and the vehicle speed-correction coefficient map shown in FIG. It is determined appropriately through experiments according to the characteristics of the object. In addition, if the range of camber angle control for each wheel is limited due to reasons such as the proximity of each wheel to a vehicle body side member, etc., the camber angle control may be performed only within the positive range. It is also possible to configure the configuration so that it is executed only on the negative side, or so that it is executed over both the positive side and negative side ranges.

In the above embodiment, the present invention is applied to a type of vehicle in which the center point M of the lateral pressing force acting on the vehicle due to a crosswind is located in front of the vehicle's center of gravity G, as shown in FIG. However, as shown in FIG. 7, the present invention is applied to a type of vehicle in which the center point M of the lateral pressure acting on the vehicle due to a crosswind is located behind the vehicle's center of gravity G. Explain an example.

This embodiment is basically the same as the embodiment shown in Figs. 1 to 6, except for the wind pressure shown in Fig. 5.
The reason is that a wind pressure-camber angle map shown in FIG. 8 is used in place of the camber angle map. In other words, since the center point M is located behind the center of gravity G, when a crosswind is encountered while driving straight, the vehicle behaves in a manner opposite to that of the type of vehicle shown in Figure 4. The control direction of the camber angle of the map shown in FIG. 8 is set in the opposite direction to the control direction of the camber angle of the map shown in FIG.

According to this embodiment, when the vehicle receives a crosswind from the left side while driving straight, for example, due to the characteristics shown in FIG.
Normally, the vehicle exhibits a behavior of trying to turn left, but the camber angle of each wheel is controlled by a control signal from the controller 32, and the camber angle of the left wheel is negative for the front wheels, the camber angle of the right wheel is positive, and the camber angle of the rear wheels is negative. Regarding the wheels, the camber angle of the left wheel is controlled positively and the camber angle of the right wheel is controlled negatively. As a result, the canvas thrust force of each wheel acts in a direction that cancels out the above-mentioned behavior of the vehicle attempting to turn to the left, making it possible to significantly improve the straight-line stability of the vehicle in the event of a crosswind.

In addition, in the embodiments described according to FIGS. 7 and 8, the camber angle control may be configured to be executed only in the positive side range, or configured to be executed only in the negative side range. Alternatively, it is also possible to configure it to be executed over both the positive side and negative side ranges.

Furthermore, the embodiments described according to FIGS. 1 to 6 and the embodiments described according to FIGS. 7 and 8 are configured so that camber angle control is executed for all wheels when a crosswind is received. However, (i) it is configured to perform camber angle control only on the front wheels or only on the rear wheels, or (ii) it is configured so that camber angle control is performed only on wheels located on one diagonal line in plan view. It is also possible. Furthermore, (iii) it is also possible to provide an actuator that controls the camber angle of only the front wheels or only the rear wheels, so that the camber angle control is executed only for one of the left and right wheels when a crosswind is encountered. . In the case of (11) or (iii) above, it is preferable to perform camber angle control for the wheels corresponding to the direction of the vehicle's yaw displacement.In other words, if the vehicle is caused by a crosswind to cause a clockwise yaw displacement in a plan view, for example. 5 6 , it is effective to perform camber angle control for the front right wheel and/or the rear left wheel.

Next, an embodiment will be described in which the present invention is applied to a type of vehicle in which the center point M of the lateral pressing force acting on the vehicle due to crosswinds almost coincides with the center of gravity G of the vehicle, as shown in FIG. .

This embodiment is basically the same as the embodiment shown in Figs. 1 to 6, but the difference is that the wind pressure -
The reason is that a wind pressure-camber angle map shown in FIG. 10 is used in place of the camber angle map. That is, the center point M
Because G almost coincides with the center of gravity, the vehicle behaves as if it were drifting to the side with almost no yaw displacement.The direction of camber angle control in the map shown in Figure 10 deals with this. It is set as follows.

According to this embodiment, when the vehicle receives a crosswind from the left side while driving straight, for example, due to the characteristics shown in FIG.
Normally, the vehicle exhibits a behavior in which it tries to flow to the right without causing yaw displacement, but the camber angle of each wheel is controlled by a control signal from the controller 32, and the camber angle of the left wheel of the front wheel is negative, and the camber angle of the right wheel is negative. The camber angle of the rear wheels is controlled to be positive, the camber angle of the left wheel is controlled to be negative, and the camber angle of the right wheel is controlled to be positive. As a result, the canvas thrust force of each wheel acts in a direction that cancels out the above-mentioned behavior of the vehicle that tends to drift to the right, making it possible to significantly improve the straight-line stability of the vehicle during crosswinds.

In the embodiments described according to FIGS. 9 and 10, the camber angle control may be configured to be executed only in the positive side range, or configured to be executed only in the negative side range. Alternatively, it is also possible to configure it to be executed over both the positive side and negative side ranges. Furthermore, it is also possible to configure the system so that the camber angle control when subjected to a crosswind is executed not for all wheels but only for some wheels. For example, it is executed only for wheels located on one diagonal line in a plan view. Alternatively, it is also possible to perform the process on only one of the left and right wheels (preferably the front and rear wheels on the leeward side).

Furthermore, the controller 32 shown in FIG.
Therefore, by preparing a ROM in which the required wind pressure-camber angle map and vehicle speed correction coefficient map are stored, it is possible to implement this method on vehicles with different characteristics simply by replacing the ROM. Can be done.

The suspensions in each of the above embodiments are all strut types, but other types of suspensions may also be of the type that can control the camber angle of the wheels by interposing actuators between the wheel support member and the vehicle body. The present invention can be easily applied to any suspension. Further, the actuator is not limited to the hydraulic type as in the above embodiment, but it is also possible to use, for example, an electric type actuator.

〔effect〕

According to the present invention, when a crosswind acts on the vehicle while the vehicle is running, the wind pressure sensor detects the crosswind, and the control means adjusts the camber angle of the wheel using the actuator so as to reduce changes in vehicle behavior due to the crosswind. control, it is possible to prevent the running stability from deteriorating even in the presence of crosswinds, and this has the effect of largely eliminating constraints on conventional vehicle design, such as devising suspensions and body shapes. play.

[Brief explanation of the drawing]

FIG. 1 is an overall explanatory diagram showing one embodiment of the present invention, FIG. 2 is a front view showing an example of how the actuator shown in FIG. 1 is mounted, and FIG. 3 shows the operation of the controller 32 shown in FIG. Flowchart for explanation; FIG. 4 is an explanatory diagram showing vehicle characteristics in the above embodiment; FIG. 5 is an explanatory diagram showing a wind pressure-camber angle map stored in the ROM 34 of the controller 32;
FIG. 6 is an explanatory diagram showing a vehicle speed-correction coefficient map stored in the ROM 34, FIG. 7 is an explanatory diagram showing vehicle characteristics in another embodiment, and FIG. 8 is a wind pressure diagram in the embodiment of FIG. An explanatory diagram showing a camber angle map, FIG. 9 is an explanatory diagram showing vehicle characteristics in yet another embodiment, and FIG. 10 is an explanatory diagram showing a wind pressure-camber angle map in the embodiment of FIG. be. 2.4, 6.8...actuator, 10.12゜1
4.16...Control valve, 32...Controller, 36
...Wind pressure sensor

Claims (1)

[Claims] an actuator that adjusts the camber angle of the wheel; a wind pressure sensor that detects a crosswind acting on the vehicle body; and when the wind pressure sensor detects that the crosswind has acted on the vehicle body, a canvas thrust force of the wheel is generated by the crosswind. A wheel camber angle control device comprising: control means for driving the actuator to control the camber angle of the wheel so as to change in a direction that reduces changes in vehicle behavior.