JPH03231016A - Camber angle control device for wheel - Google Patents

Abstract

PURPOSE:To improve stable running performance as well as cornering performance by controlling actuators to regulate the camber angle of each wheel, based on lateral acceleration exerted on a vehicle and a car speed when necessary. CONSTITUTION:Actuators 2, 4, 6, and 8 having hydraulic cylinder constitution to regulate the camber angle of each of front and rear wheels are provided. Electromagnetic control valves 10, 12, 14, and 16 are located in a feed passage 18, connected to the delivery side of a pump 20, so that the actuators 2-8 are controlled. The control valves 10-16 are controlled through a drive circuit 30 by means of a controller 32 according to the running state of a vehicle. In control effected by means of the controller 32, output signals from a car speed sensor 40 and a lateral acceleration sensor 50 are inputted to the controller 32, and the control valves 10-16 are controlled based on lateral acceleration exerted on a vehicle and a car speed where necessary. This constitution improves stable running performance as well as cornering performance.

Description

DETAILED DESCRIPTION OF THE INVENTION ['Industrial Field of Application] The present invention relates to a wheel camber angle control device suitable for automatically controlling the camber angle of a wheel in an automobile depending on the driving situation.

[Prior Art] Conventionally, devices have been proposed that automatically control the camber angle of vehicles such as automobiles according to the driving conditions. The one shown in Publication No. 62-125952 is known.

[Problem to be solved by the invention] By the way, in automobiles, suspensions, tires, etc. are set to ensure steering stability when driving straight and when turning. Since this is done based on a driving condition model, if the driving condition differs from this model, sufficient driving stability may not be obtained.

This running stability becomes more important as the vehicle speed increases, but if the characteristics of the suspension are constant, if the suspension is set to obtain the optimum running stability at high speeds, it will be possible to stabilize the running stability at low speeds. If the suspension is set to provide optimum running stability at low speeds, the running stability at high speeds is likely to be insufficient.

Furthermore, even if the running speed is the same, the required running stability will differ depending on whether you are driving straight or turning.
In particular, when turning, a turning performance is required that allows the vehicle to turn smoothly while stabilizing the vehicle body in accordance with the vehicle speed.

Therefore, it is possible to change the characteristics of the suspension according to the vehicle speed and steering conditions.One of the alignment elements that determines the characteristics of such suspension is the camber angle of the wheels, and by adjusting the camber angle,
One possibility is to control the running stability of the vehicle.

However, with conventional wheel camber angle control devices,
No such control was in place.

In addition, when controlling the camber angle, it is possible to control it based on the vehicle's driving condition, but the specific elements of the vehicle's driving condition should correspond as much as possible to the actual posture and behavior of the vehicle. is desirable.

The present invention has been made in view of the above-mentioned problems, and makes it possible to improve running stability performance including turning performance by controlling the camber angle of the wheels based on the actual running condition of the vehicle. The object of the present invention is to provide a wheel camber angle control device.

[Means for Solving the Problems] Therefore, the wheel camber angle control device according to claim 1 of the present invention is provided in one or both of the front wheels and the rear wheels in a vehicle equipped with front wheels and rear wheels. an actuator for adjusting the camber angle of the vehicle; a lateral acceleration detection means for detecting lateral acceleration of the vehicle; and a control means for controlling the actuator based on the lateral acceleration detected by the lateral acceleration detection means. It is characterized by the presence of

Further, the wheel camber angle control device according to claim 2 of the present invention is provided in a vehicle having front wheels and rear wheels, and includes an actuator provided on one or both of the front wheels and the rear wheels to adjust the camber angle thereof. , lateral acceleration detection means for detecting lateral acceleration of the vehicle, vehicle speed detection means for detecting the vehicle speed of the vehicle, lateral acceleration detected by the lateral acceleration detection means and vehicle speed detected by the vehicle speed detection means. The invention is characterized in that it includes a control means for controlling the actuator based on the actuator.

[Function] According to the wheel camber angle control device according to claim 1 of the present invention, the lateral acceleration of the vehicle is detected by the lateral acceleration detection means, and the lateral acceleration detected by the lateral acceleration detection means is controlled by the control means. The actuator is controlled based on the acceleration, and the camber angle of each wheel is adjusted by this actuator.

According to the wheel camber angle control device according to claim 2 of the present invention, the lateral acceleration detection means detects the lateral acceleration of the vehicle, and the vehicle speed detection means detects the vehicle speed, and the control means detects the lateral acceleration. The actuator is controlled based on the lateral acceleration detected by the means and the vehicle speed detected by the vehicle speed detection means, and by this actuator,
The camber angle of each wheel is adjusted.

[Embodiment] Hereinafter, embodiments of the present invention will be explained with reference to the drawings. Figs. 1 to 10 show a wheel camber angle control device as a first embodiment of the present invention, and Fig. 1 shows a device for controlling a wheel camber angle. Fig. 2 is a front view of the main parts of the vehicle body showing an example of how the actuator is installed, Fig. 3 is a flowchart explaining its operation, and Fig. 4 is a camber angle based on lateral acceleration and vehicle speed. Fig. 5(a) and (b) are diagrams showing a control area map (map ■) stored in the ROM of the controller to determine the control area of the controller.
Control area stored in - camber angle map (map ■)
FIG. 6 is a diagram showing the vehicle speed-camber angle map (map ■) stored in the ROM of the controller. FIG. 7 is a diagram showing the relationship between the load applied to the wheel and the camber angle correction coefficient. Figure 8 is a diagram showing the relationship between the steering angle and the camber angle correction amount, Figure 9 is a diagram showing the relationship between changes in wheel stroke and camber angle, and Figure 10 is a diagram showing the relationship between the vehicle body roll angle and the camber angle. and the camber angle; 12
The figure shows a wheel camber angle control device as a second embodiment of the present invention, and FIG. 1-1 is a flowchart explaining its operation, and FIG. 12(a).

(b) is a diagram showing a lateral acceleration-camber angle map (map 11') stored in R, OM of the controller.

First, a description will be given of the first embodiment 1m, and the wheel angle control device of this embodiment is 4") corresponding to claim 2 of the present invention.

In Fig. 1, 1C, 2 is the right front shaft 17 + actuator for adjusting the camber angle, 4 is the 7 tuator for adjusting the camber angle of the right front trunk, (:'; J:j-left rear wheel). The actuator r'l is an actuator that adjusts the camber angle of the right rear wheel, and r'l is an actuator that adjusts the camber angle of the right rear wheel. The actuator A is provided as shown in Fig. 2. That is, Fig. 2 is a front view of the automobile, and the actuator A is installed between the upper end of the strut S of the strut type suspension and the vehicle body F. By extending or contracting, the upper end position of the strut S is displaced in the vehicle width direction, thereby making it possible to adjust each camber θ of each vehicle @W.
-7.

Each actuator 2, 4, 6 and 8 is driven by an electromagnetic control valve 10, 12, 14 and 16, respectively. Each control valve io, J. 2, 14 and j6.

The pump 20 is connected to a pump 20 via a combined feed line 18 and to an oil reservoir 24 via a discharge line 22. The pump 20 is immediately driven by an engine/etc. The oil inside is sucked (, 7 and discharged to the supply path 18).

A reservoir 24 is connected to the supply path 1B via a relief valve 28, and a reservoir 24 is connected to the supply path 1B through a relief valve 28.

8 is now able to maintain the 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 and from the actuators 2 to 8 is prohibited and locked, and a first position in which each of the actuators 2 to 8 is locked, in response to 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. .

Reference numeral 32 denotes a controller as a control means for outputting a control signal to the quick-acting rotation g3o. is output to control the actuators 2 to 8.

Therefore, within the controller 32, there is a ROM (storage means) 34. Furthermore, although not shown, an input circuit for inputting output signals from each sensor, a CPU for executing calculations and processing in accordance with the progera l, and F2. It includes AM and output circuits as well as interfaces between these elements.

The above-mentioned sensors include a well-known vehicle height sensor 36 that detects the vehicle height of each vehicle fmW, that is, the vehicle height of each part of the left front wheel, right front axle, left rear wheel, and right rear wheel, and a steering wheel (not shown). a steering sensor (steering angle detection means) 38 that detects the steering angle of the steering wheel, a vehicle speed sensor (vehicle speed detection means) 40 that detects the vehicle speed, a displacement sensor 42 that detects the stroke position of the actuator 2 of the left front wheel, and a displacement sensor 42 that detects the stroke position of the actuator 2 of the front right wheel. Displacement sensor 4 that detects the stroke position of actuator 4
4, a displacement sensor 46 that detects the stroke position of the actuator 6 of the left rear wheel, a displacement sensor 48 that detects the stroke position of the actuator 8 of the 4 right rear wheel, and a lateral acceleration that detects the lateral acceleration (lateral G) of the vehicle. A sensor 50 and a load sensor (not shown) for measuring the load for each 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 program processing according to the flowchart shown in FIG. 3 when an engine switch (ignition 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 50 are read and stored in a predetermined memory area.

Next, the process advances to step S3, and the vehicle speed ■ stored in step S2 is the set vehicle speed ■. Determine whether it is the above. This set vehicle speed V. Here, a vehicle speed of about 10 to 20 km/h is set, but other low speed values may be set.

If rYEsJ is determined in step S3, the process proceeds to step S4, where the magnitude of the steering angle δ (that is, δl) is set to the preset steering angle δ. It is determined whether it is smaller than .

When the vehicle is in a turning state, 1δl becomes δ. Therefore, the process proceeds to step S5, and from maps I and II, the target value (target camber angle) θ of the camber angle of the wheel W is determined based on the lateral acceleration generated in the vehicle body and the vehicle speed.

However, since the target camber angle obtained in step S5 is corrected in the subsequent step S9, the reference target camber angle θ
, is called.

In addition, in the following explanations, items that apply to the front wheel are marked with F, items that apply to the rear wheel are marked with R, and items that apply to the inside wheel of the turn are marked with ``work'', and items that apply to the outside wheel of the turn are referred to as ``work''. are distinguished by adding O. For example, the target camber angle of the front inner wheel is θtFI, the target camber angle of the front outer wheel is θtFo, and the target camber angle of the rear inner wheel is θt.
RI, the target camber angle of the rear wheel on the outside of the turn is expressed as θtRo.

The map ■ is as shown in FIG. 4(a) for the front wheels, and as shown in FIG. 4(b) for the rear wheels.

The reference target camber angle θ in this step S5. As shown in Fig. 4, map I used for setting the control area is divided into multiple stages (1 in the figure) depending on the magnitude G of the lateral acceleration and the vehicle speed ■.
9)), and the lateral acceleration G
is the classification value G, G2゜G3. G4 (G engineering〈G2kuG3〈
G4) is divided into five parts, and the speed V is divided into five parts by the division value V, v2
．． v,, v4 (v□〈V2〈v,〈■4) is divided into five areas, and the number of control regions (1 to 9) increases as the lateral acceleration G and vehicle speed ■ increase. ing.

Similarly, the map ■ used in this step S5 indicates the reference target camber angle θ corresponding to the number of control areas determined in the map I described above. The number of control regions is determined by comparing the value of lateral acceleration G detected by lateral acceleration sensor 50 and the value of vehicle speed V detected by vehicle speed sensor 40 with map ■.
The reference target camber angle θ corresponding to the number of control regions is determined by comparing the obtained number of control regions (1 to 9) with map (2). It is decided.

Regarding map H, as for the front wheels, in the low control region (number of control regions 1), the reference target camber angle θ and FI of the wheels on the inside of the turn are constant values on the positive side, as shown in Fig. 5(a). , the standard target camber angle θ of the wheel on the outside of the turn
iFo is set to a constant value on the negative side, and in the intermediate control region (region from 1 to 5 control regions), the standard target camber angle θ of the wheel on the inside of the turn, and FI changes from the positive side to neutral as the speed increases. decrease to the side,
The standard target camber angle θ□FO for the wheels on the outside of the turn is set to increase from the negative side to the neutral side as the speed increases, and in large control areas (regions with 5 or more control areas), the standard target camber angle θ□FO for the wheels on the inside of the turn is set to increase from the negative side to the neutral side as the speed increases. Target camber angle θ
LFI is also the reference target camber angle 01Fo of the wheel on the outside of the turn.
Both are set to neutral (that is, ±O).

Regarding the rear wheels, as shown in FIG. 5(b), in a low control region (the number of control regions is 1), the reference target camber angle 0tRI of the wheel on the inside of the turn is a constant value on the negative side,
The reference target camber angle θ□RO of the wheel on the outside of the turn is set to a constant value on the positive side, and in the intermediate control region (region from control region number 1 to 5), the reference target camber angle θ□RO of the wheel on the inside of the turn is set to a constant value on the positive side. 3xRI is set so that it increases from the negative side to the positive side as the speed increases, and the standard target camber angle θ□RO of the wheel on the outside of the turn decreases from the positive side to the negative side as the speed increases. In a region with a number of regions of 5 or more), the standard target camber angle θ□R for the wheel on the inside of the turn is set to a constant value on the positive side, and the standard target camber angle θiRo of the wheel on the outside of the turn is set to a constant value on the negative side. There is.

In this way, in step S5, the reference target camber angle θxF'Lr θIFOI θiRI+ θ of each wheel is determined.
□Once RO is determined, in the subsequent step S9, a first correction is applied to each of the determined reference target camber angles θxFI to θxRo.

This first correction includes a correction that takes into account changes in the canvas thrust force due to the vehicle's load (load correction), a correction that takes into account changes in camber angle caused by corner steering (steering correction), and Corrections that take into account changes in camber angle due to changes in suspension stroke (stroke change correction) and corrections that take into account changes in camber angle due to vehicle body roll (camber angle correction during roll) are now applied. .

Load correction is to correct the change in the camber angle according to the change in canvas thrust force caused by the loading state of the vehicle. For example, the load (or total weight of the vehicle body) We applied to the vehicle and the camber The relationship with the angle correction coefficient, etc. is stored as a map in the controller 32, and the load We is determined based on the load detection information from the load sensor provided for each wheel.
The camber angle correction coefficient and the like are determined from e. For example, there is a relationship between the load We and the camber angle correction coefficient as shown in FIG. 7.

The characteristic shown in FIG. 7 shows the relationship between the load We and the reciprocal P of the correction coefficient for the Cuyamba angle, and as We increases, the reciprocal P of the correction coefficient increases almost linearly. However, when considering the canvas thrust force, it is better to consider the tire's eigenvalue, and in this case, the load We
The characteristics of the camber angle relative to the angle are not linear as described above.

The correction during steering is to correct the change in the camber angle caused by steering itself.The relationship between the steering angle and the change in the camber angle is stored in the controller 32 as a map, and this map and the steering angle are stored in the controller 32 as a map. The correction amount of the camber angle is determined from the steering angle information detected by the sensor 38. The relationship between the steering angle and the camber angle change is as shown in FIG. 8, for example, and it is possible to determine the camber angle correction amount according to the steering angle δ.

In general, when the suspension stroke of the wheel W changes due to bumps, rebounds, acceleration/deceleration conditions, vehicle speed, etc., the camber angle θ of the wheel W changes accordingly, so correction at the time of stroke change corresponds to such a suspension stroke. For example, the relationship (map) between the stroke and the camber angle as shown in FIG. 9 is stored in the ROM of the controller 32.
The reference target camber angle θ of each wheel W is corrected by the camber angle (stroke-corresponding camber angle) that changes according to the stroke change ΔL of each wheel W.

Since the camber angle of each wheel changes depending on the roll state of the vehicle, the roll camber angle correction is to correct the change in the camber angle due to the roll of the vehicle. The angle φ is calculated, and the relationship between the roll and camber angle (as shown in FIG. 10, for example) is calculated.
map) in the ROM of the controller 32,
The standard target camber angle θ1 of each wheel W is equal to the camber angle (roll camber angle) corresponding to the change Δφ in the roll angle φ.
Correct.

Note that the above-mentioned load We can be calculated based on the load detection value detected for each wheel, and within the controller 32, this load We is calculated for each control cycle, and this calculated value is combined with the above-mentioned load We. Calculate the correction coefficient from the map (see Figure 7). The stroke L and roll angle φ of the suspension can be calculated by a known calculation method based on the inspection information of the vehicle height sensor 36 of each wheel W, and the controller 32 calculates the vehicle height at each control cycle. sensor 3
These values, φ, are calculated from the detected values of No. 6, and each correction amount is determined from these calculated values and the above-mentioned map (see FIGS. 9 and 10).

Further, each of the maps shown in FIGS. 7 to 10 described above is one example, and the maps have different characteristics depending on the configuration of each part of the vehicle. Further, the size of the vertical axis (camber angle) of the map in FIG. 7 does not necessarily correspond to map I, and often takes a relatively smaller value than the value of the camber angle represented by map r.

On the other hand, when the vehicle is traveling almost straight, 1δ1 becomes smaller than δ0, so the process goes to step S6, and in the 6th can angle setting section, the target value of the camber angle of the wheel S' (target camber angle ) θ, first find the reference target camber angle On.

As shown in FIG. 6, this map (2) is the target camber angle θ for the front wheels, and F is the target camber angle θ for the rear wheels. R is set on the negative side, but both are close to neutral at low speeds, and as the vehicle speed increases, they tend to be more positive or negative, and at set vehicle speeds ■ 4 or higher, they are respectively constant positive or negative. It is set to take a negative value. In addition.

In this case, the left and right wheels are set to the same target camber angle.

In this way, in step S6, the reference target camber angle of each wheel is set to 0. Once F, θ, and R are determined, the following step S8
Then, each of the above-mentioned standard target camber angles θxFt θ
, R are subjected to the second correction.

In this second correction, the load correction, stroke change correction, and roll camber angle correction described in the first correction are performed.

On the other hand, the vehicle speed ■ is the set vehicle speed ■. If it is smaller than the target camber angle (target value) θtF+θtR of the camber angle of the wheel W, the process proceeds to step S7 and sets the preset reference value OaF+OaR as the target camber angle (target value) θtF+θtR. In this way, the reason for fixing the camber angle θ to a constant reference value is that in such a low speed region, even if the camber angle θ is controlled by 3PJ, the practical effect is small, and it is rather to reduce the control frequency and simplify the control. This is because it is more advantageous to do so.

Note that the reference value θoF+θ. Both R are often set to a neutral state (that is, ±O), but one or both may be set to a slightly positive side or a slightly negative side. For example, the above map ■
As in, vehicle speed■. If the camber angle of the front wheels is set to the positive side and the camber angle of the rear wheels is set to the negative side, the reference value θ of the two front wheels is set so that it is almost continuous with the value of V=Vo in the map. It is conceivable to set F to the positive side and the rear wheel reference value O9R to the negative side2 In this way, each step S 9 + S 8 t S
In step 7, the target camber angle θ is set ^, step 51
．． 0, and in the camber angle control section, the controller 32
A control signal is output to the motion part of each actuator 2, 4, and 6.8 through the motor to operate one actuator 24.6.8 so that the camber angle θ of 1 mW for each car becomes the target value θ. The upper end position of the strut/rat S is driven in the vehicle width direction.

After completing the process of step SIO in this manner, the process returns to step S2/\ and repeats the process from step S2 described above. Therefore, while the vehicle is running, the four actuators 2 to 8 continuously control the camber of each vehicle @W at predetermined intervals based on the vehicle speed, suspension stroke, and roll state of the vehicle body. It should be noted that the repetition of the processing from step S2 onwards may take J cycles for several milliseconds, depending on the capabilities of the CPU in the controller 32, etc.
It is done as a degree.

According to the wheel camber angle control device of this embodiment configured in this way, when the vehicle is traveling at a low speed or in a erratic state, the camber angle is set to a reference value close to a preset neutral state, so that the turning of the front and rear wheels is controlled. The grip handle is set close to neutral, and the steering characteristics are set close to neutral.

This ensures straight-line stability and steering performance when driving at low speeds.

Furthermore, during this low-speed running (at V), the camber angle is fixed to the reference value and no special camber angle adjustment is performed, so the frequency of control in this region can be reduced.

Then, the vehicle speed V increases to the set vehicle speed ■. When this is the case, the camber angle O is controlled according to the vehicle speed V and the steering angle δ.

In other words, when driving straight ahead, until the vehicle speed V becomes equal to or higher than the set vehicle speed Vn and reaches the set vehicle speed V4, the rear wheel side camber angle OR changes to the front wheel side camber angle θ as the vehicle speed increases.
It is controlled to be more negative with respect to F.

Therefore, as the vehicle speed increases, the turning grip force of the rear wheels increases compared to the turning grip force of the front wheels, and the steering characteristics of the vehicle tend to understeer.

This improves the straight-line stability of the vehicle as the vehicle speed increases, allowing stable high-speed travel.

Furthermore, when the vehicle speed V increases to the set vehicle speed ■4 or more, the rear wheel side camber angle θR is set to a more negative side with respect to the front @ side camber angle θF, taking into account wheel stroke changes and vehicle body roll state. The current state is maintained, so
As described above, straight-line stability is ensured while stabilizing the posture of the vehicle body. In addition, since each camber angle θ is prevented from being displaced beyond a certain level, adverse effects caused by changes in camber angle, such as excessive camber angle and deterioration of initial turning performance or increased tire wear, can be avoided. There is no need to invite anyone.

Moreover, in this camber angle control when traveling straight, load correction, stroke change correction, and roll camber angle correction are performed as second corrections, so the vehicle speed is not affected by changes in the vehicle's live load. There are benefits to always doing it properly.

On the other hand, when the vehicle is turning, the camber angle θ of each corner wheel is
is controlled according to the vehicle speed (■) and the lateral acceleration G as follows.

In other words, in a control region where vehicle speed ■ and lateral acceleration G are low, the camber angle θtFI of the front wheel on the inside of the turn is set to a constant value on the positive side, and the camber angle 0tFO of the front wheel on the outside of the turn is set to a fixed value on the negative side. Rear wheel camber angle θt
RI is set to a constant value on the negative side, and the camber angle θtRo of the rear wheel on the outside of the turn is set to a constant value on the positive side.

In addition, in an intermediate control region where vehicle speed V and lateral acceleration G are both intermediate, vehicle speed is high but lateral acceleration G is small, or vehicle speed V is small but lateral acceleration G is large, the front wheel on the inside of the turn The camber angle θtFI of the vehicle is set to decrease from the positive side to the neutral side as the speed increases, and the camber angle θtFo of the front wheel on the outside of the turn is set to increase from the negative side to the neutral side as the speed increases.

The camber angle θtRI of the rear wheel on the inside of the turn is set to decrease from the negative side to the positive side as the speed increases, and the camber angle θtRo of the rear wheel on the outside of the turn is set to increase from the positive side to the negative side as the speed increases. .

In a control region where both vehicle speed V and lateral acceleration G are large, the standard target camber angle θtFI of the front wheel on the inside of the turn is also the standard target camber angle θtF of the front wheel on the outside of the turn.

are both set to neutral (i.e. ±O),
The standard target camber angle θtRo of the rear wheel on the inside of the turn is set to a constant value on the positive side, and the standard target camber angle θtRo of the rear wheel on the outside of the turn is set to a constant value on the negative side.

Therefore, the lower the vehicle speed V and the smaller the lateral acceleration G generated on the vehicle body, the smaller the canvas thrust force on the rear wheels becomes compared to the canvas thrust force on the front wheels, resulting in oversteer (or slight oversteer tendency). This greatly improves turning ability. The lateral acceleration G is small because
Even if the vehicle speed is low or the vehicle speed V is relatively high, the steering angle δ
is small and the running stability of the vehicle is high, so even if the steering characteristics are set to oversteer and priority is given to turning performance as described above, running stability is maintained.

As a result, the turning performance, including the turning performance required at low speeds and low lateral accelerations, is significantly improved.

As the vehicle speed V or lateral acceleration G increases, the canvas thrust force on the front wheel side decreases and becomes a constant value, while the canvas thrust force on the rear wheel side increases.
The steering characteristics change from oversteer to neutral steer and then to understeer. For this reason, depending on the speed and lateral acceleration, that is, as running stability is required, running stability is prioritized over single turning performance, and depending on the running condition, turning performance and walking stability. You will be able to gain sex.

Furthermore, when the vehicle speed V and lateral acceleration G increase, the canvas thrust force on the rear wheel side becomes relatively large compared to the canvas thrust force on the front wheel side, resulting in understeer (or understeer tendency), and when driving at high speed or lateral acceleration. Driving stability, which is particularly required when

In particular, in the intermediate range and below, the camber angle of the front wheels is set to neutral, and the desired steering characteristics are obtained by adjusting the camber angle of the rear wheels. Since the front wheels, which provide the driving force, do not exhibit complicated behavior when driving at high speeds, control becomes more stable, and
This has the advantage that control itself becomes easier.

Moreover, in the above-mentioned camber angle control, various corrections such as load correction, correction at the time of seven stroke changes during steering, and camber angle correction during roll are applied as the first correction, so that it depends on the vehicle speed and steering angle. The control of the camber angle is based on changes in the vehicle's payload, turning steering itself, wheel bumps and rebounds caused by disturbances such as road surface conditions and wind, and changes in vehicle body posture and vehicle height due to acceleration/deceleration conditions, vehicle speed, etc. The camber angle θ of each wheel in this case is controlled in accordance with changes in speed V and lateral acceleration G. Since the adjustment is relatively smooth, the above-mentioned improvement in driving performance can be obtained without impairing the steering feeling.

Next, explaining the second embodiment, the wheel camber angle control device of this embodiment corresponds to claim 1 of the present invention, and the configuration of the device is the same as that of the first embodiment (see Figs. 1 and 2). ), but the process executed by the controller 32 is different from the first embodiment, and this process will be explained according to the flowchart shown in FIG.

As shown in FIG. 11, in the control of this embodiment, base 1! in step S5! ! The setting of the camber angle is different from the first embodiment.

That is, in step S5 of this embodiment, the target value (target camber angle) θ of the camber angle of the wheel W is obtained from the map ■′ based only on the lateral acceleration generated in the vehicle body.
Vehicle speed is not considered.

The map ■ used in this step S5 is shown in Fig. 12(a).
, (b), and for the front wheels, as shown in Fig. 12 (a), when the lateral acceleration G is small, the reference target camber angle θIFI of the wheel on the inside of the turn is on the positive side. to a constant value.

The standard target camber angle θIFO of the wheel on the outside of the turn is set to a constant value on the negative side, and when the lateral acceleration G is of an intermediate magnitude, the standard target camber angle θIFO of the wheel on the inside of the turn is set to a constant value on the negative side.
□F work is set so that it decreases from the positive side to the neutral side as the speed increases, and the reference target camber angle θ + FO of the wheel on the outside of the turn is set so that it increases from the negative side to the neutral side as the speed increases, and the lateral acceleration G is large. In this case, both the standard target camber angle θYFI of the wheel on the inside of the turn and the standard target camber angle θxFo of the wheel on the outside of the turn are set to neutral (that is, ±O).

Regarding the rear wheels, as shown in Fig. 12(b),
When the lateral acceleration G is small, the reference target camber angle θ, RI of the wheel on the inside of the turn is set to a constant value on the negative side, and the reference target camber angle θzRo of the wheel on the outside of the turn is set to a constant value on the positive side. When the acceleration G has an intermediate magnitude, the reference target camber angle θ+R of the wheel on the inside of the turn
I decreases from the negative side to the positive side as the speed increases, and the reference target camber angle θxR of the wheel on the outside of the turn
0 is set to increase from the positive side to the negative side as the speed increases, and when the lateral acceleration G is large, the reference target camber angle θ, RI of the wheel on the inside of the turn is set to a constant value on the positive side, and when the wheel on the outside of the turn The reference target camber angle θ+, RO of the wheel is set to a constant value on the negative side.

The first correction in step S9 following step S5 is the same as in the first embodiment, and the other steps are also the same as in the first embodiment.

In the wheel camber angle control device of the second embodiment configured as described above, the camber angle θ of each square wheel is controlled as follows according to the lateral acceleration G when the vehicle is turning.

In other words, when the lateral acceleration G is small, the camber angle θtFI of the front wheel on the inside of the turn is set to a constant value on the positive side, and the camber angle θtF'O of the front wheel on the outside of the turn is set to a constant value on the negative side. Camber angle of the wheel θtRI
is set to a constant value on the negative side, and the camber angle θtRo of the rear wheel on the outside of the turn is set to a constant value on the positive side.

Furthermore, when the lateral acceleration G is of intermediate magnitude, the camber angle θtFI of the front wheel on the inside of the turn decreases from the positive side to the neutral side as the speed increases, and the camber angle θtFo of the front wheel on the outside of the turn decreases as the speed increases. increases from the side to the neutral side. The camber angle OtRT of the rear wheel on the inside of the turn decreases from the negative side to the positive side as the speed increases, and the camber angle θtRo of the rear wheel on the outside of the turn increases from the positive side to the negative side as the speed increases. It is set as follows.

When the lateral acceleration G is large, both the standard target camber angle θtFI of the front wheel on the inside of the turn and the standard target camber angle θtFo of the front wheel on the outside of the turn are both neutral (that is,
±0), the reference target camber angle θtRI of the rear wheel on the inside of the turn is set to a constant value on the positive side, and the reference target camber angle RtRo of the rear wheel on the outside of the turn is set to a constant value on the negative side.

Therefore, as the lateral acceleration G generated in the vehicle body decreases, the canvas thrust force on the rear wheels becomes relatively smaller than the canvas thrust force on the front wheels, resulting in oversteer (or a slight oversteer tendency), which greatly improves the ability to turn the head once. do. If the lateral acceleration G is small, the running stability of the vehicle is usually high, so even if the steering characteristics are set to oversteer and priority is given to turning performance as described above, running stability is maintained.

As a result, turning performance at low lateral accelerations is significantly improved.

As the lateral acceleration G increases, the canvas thrust force on the front wheels decreases and becomes a constant value, but the canvas thrust force on the rear wheels increases, and the steering characteristics change from oversteer to neutral steer. It becomes even more understeer. For this reason, as lateral acceleration increases and driving stability is required, driving stability is given priority over turning performance, and it is necessary to obtain turning performance and driving stability suitable for the driving condition. become.

Furthermore, when the lateral acceleration G increases to a certain level, the canvas thrust force on the rear wheel side becomes relatively larger than the canvas thrust force on the front wheel side.

When the vehicle understeers (or tends to understeer) and the lateral acceleration is large, driving stability, which is particularly required, is greatly improved.

Moreover, since the above-mentioned camber angle control is subjected to the first correction, the camber angle control is always performed appropriately, as in the first embodiment, and is relatively smooth in response to changes in the lateral acceleration G. Since the camber angle is adjusted, as in the first embodiment, it is possible to improve the driving performance without impairing the steering feel.

In this way, in the second embodiment, the camber angle control during turning is performed according only to the lateral acceleration, which is a guideline for the running stability of the vehicle body, without considering the vehicle speed. Control can be simplified while still achieving effectiveness.

Note that maps I and n shown in FIGS. 4 to 6 and 12.

The characteristic maps shown in m, n' and FIGS. 7 to 10 are stored in the ROM 34 in the controller 32, and the numbers are set according to the characteristics of the vehicle in order to obtain a high effect. It is desirable to determine this by experiment. Furthermore, it is desirable that each set vehicle speed, set steering angle, etc. be set to appropriate values in accordance with the characteristics of the vehicle.

In particular, for map I shown in Fig. 4, the lateral acceleration G&
It is necessary to appropriately set the classification values (G, -G, , V, -V4) for lateral acceleration G and vehicle speed V, taking into account various characteristics of the vehicle. It may be divided finely or more roughly.

Furthermore, the map IT shown in Figures 5.6 and 1.2, II
I.

In ``2'', the vertical axis (0 axis) may not be the actual size of the camber angle θ, but may be the size of the adjustment amount from the camber angle 01 when each wheel is stopped.

And to the above-mentioned first supplement or second correction.

A correction that takes into account changes in the steering angle due to the roll of the vehicle body (roll steering angle correction) and a correction that takes into account changes in the camber angle due to lateral force (lateral force correction) may be added. In this case, the steering angle correction at the time of roll corrects the change in the steering angle due to the roll of the vehicle body. Regarding the roll, the roll angle φ can be calculated based on the detected value of the vehicle height sensor 36 of each wheel, and the roll angle φ can be calculated based on the detected value of the vehicle height sensor 36 of each wheel. Based on a previously known relationship between the angle φ and the steering angle, the steering angle change caused by the roll can be determined and corrected accordingly.

In addition, lateral force correction is a method to compensate for the change in camber angle due to deformation of the suspension bushings when lateral force is applied to the vehicle, and lateral force can be calculated based on information detected by the lateral acceleration sensor. Based on the previously known relationship between the lateral force and the camber angle, it is possible to determine the amount of change in the camber angle caused by deformation of the suspension bushing, etc., and correct it accordingly.

Furthermore, due to the movement of the center of gravity of the car body that occurs when the car body rolls, the stroke-camber angle characteristics change as shown by the chain line Q, Ω2 in Figure 9, so such movement of the center of gravity of the car body must be taken into consideration. It is also conceivable to perform the correction by

Alternatively, among the above angle corrections, depending on the characteristics of the vehicle, etc.
For cases where the effect of correction is small, it may be possible to omit correction.

Furthermore, 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 is performed only within the positive range. It is also possible to configure the configuration so that it is executed in this way, to execute it only in the range of the negative side, or to execute it in both the range of the positive side and the negative side.

Furthermore, it is also possible to perform camber angle control only on the front wheels or rear wheels, or to perform camber angle control only on wheels located on one diagonal in plan view. It is possible. In this case, it is also possible to further provide (2) an actuator that performs camber angle control for only the front wheels or only the rear wheels, and to perform camber angle control for only one of the left and right axes depending on the driving condition.

The controller 32 shown in FIG.
34 can be replaced, so by preparing a ROM that stores the required roll angle-camber angle map and vehicle speed-correction coefficient map, it can be applied to vehicles with different characteristics simply by replacing the ROM. In addition, although the suspensions in the above embodiments are all strut types, even with other types of suspensions, the camber of the wheels can be adjusted by interposing an actuator between the wheel support member and the vehicle body. The present invention can be easily applied to any type of suspension whose angle can be controlled. 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.

Furthermore, such a wheel camber angle control device may be used in conjunction with other traction devices, such as a four-wheel steering device or a driving force distribution device in a four-wheel drive.
It is also conceivable to control it by merging it with other alignment elements.

[Effects of the Invention] As detailed above, according to the wheel camber angle control device according to claim 1 of the present invention, in a vehicle equipped with a front wheel and a rear wheel, one or both of the front wheel and the rear wheel. an actuator for adjusting the camber angle to vR; a lateral acceleration detection means for detecting lateral acceleration of the vehicle; and a control means for controlling the actuator in response to the lateral acceleration detected by the lateral acceleration detection means. With this configuration, it is possible to always obtain the optimum driving characteristics according to the driving condition of the vehicle, from low-speed driving range to high-speed driving range, and the driving performance of the vehicle such as turning performance and straight-line performance is improved. Significantly improved. In particular, since the value of lateral acceleration makes it easy to appropriately grasp the attitude and behavior of the vehicle, the above-mentioned control can be performed accurately.

Further, according to the wheel camber angle control device according to claim 2 of the present invention, instead of the control means of the device according to claim 12 described above, the lateral acceleration detected by the lateral acceleration detection device and the vehicle speed detection device are used. By providing a control means for controlling the actuator in accordance with the vehicle speed, it is possible to perform accurate camber angle control, and to achieve optimum camber angle control according to the vehicle driving conditions as described above. The driving characteristics of the vehicle can be obtained more reliably, and the driving performance of the vehicle, such as turning performance and straight-ahead performance, is further improved by -Ia.

[Brief explanation of drawings]

3 to 40 show a wheel camber angle control device according to a first embodiment of the present invention, FIG. 1 is a schematic diagram showing the overall configuration, and FIG. 2 is an example of how the actuator is installed. FIG. 33 is a flowchart explaining the operation, and FIG. 4 is a front view of the main parts of the vehicle body showing the operation.
Figure 51a (a) and (b) shows the control area map (map ■) stored in the OM.
A diagram showing the control area-camber angle map (massi U) stored in ONl, Fig. 6 is the ROk of the controller.
・1 Memorized vehicle speed - camber angle
Figure 7 is a diagram showing the relationship between the load applied to *@ and the camber angle correction coefficient, Figure 8 is a diagram showing the relationship between the steering angle and the camber angle correction amount, and Figure 1 is a diagram showing the relationship between the steering angle and the camber angle correction amount. ] Figure 1 shows the relationship between wheel stroke changes and camber angle.
Figure 0 is a diagram showing the relationship between the roll of the vehicle body and the camber angle, and Figures 11 and 12 are diagrams showing a wheel camber angle control device as a second embodiment of the vehicle 1121. Flowchart explaining the operation - FIG. 12(a),
(b) is a diagram showing a lateral acceleration-camber angle map (map H') stored in the ROM of the controller. 2.4,6,8. A...-actuator for adjusting camber angle, 10, 12, 14. 16... electromagnetic control valve, 18-- supply path, 20-- pump, 22-- discharge path, 24-- oil reservoir , 26--accumulator, 28--relief valve, 3 (1--drive circuit, 32--
Controller as control means, 34...-ROM in controller 32, 36-vehicle height sensor, 38... steering sensor, 40-vehicle speed sensor (vehicle speed detection means), 42,4
4. '46.48...displacement sensor, 50--lateral acceleration sensor (lateral acceleration detection means), F.--vehicle body, S.
-Strut type suspension strut, W...
Wheel.

Claims (2)

[Claims] (1) In a vehicle equipped with front wheels and rear wheels, an actuator provided on one or both of the front wheels and the rear wheels to adjust the camber angle thereof, and lateral acceleration detection means for detecting lateral acceleration of the vehicle; A camber angle control device for a wheel, comprising: control means for controlling the actuator in response to the lateral acceleration detected by the lateral acceleration detection means. (2) in a vehicle equipped with front wheels and rear wheels, an actuator provided on one or both of the front wheels and the rear wheels to adjust the camber angle thereof; and lateral acceleration detection means for detecting lateral acceleration of the vehicle; The vehicle includes a vehicle speed detection means for detecting the vehicle speed of the vehicle, and a control means for controlling the actuator in response to the lateral acceleration detected by the lateral acceleration detection means and the vehicle speed detected by the vehicle speed detection means. A wheel camber angle control device characterized by: