JP2002029400A - Attitude control device for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent drifting-out and spinning, and improve an accelerator control property by cancelling an under-steer property and/or an over-steer property caused by operation of an accelerator pedal 45 on turning. SOLUTION: When a vehicle is in a turning state and pedaling operation speed of the accelerator pedal 45 is equal to a predetermined speed or more, braking force is applied to a turning inner wheel of rear wheels 3 and 4 at left and right. When the vehicle is in the turning state and returning operation speed of the accelerator pedal 45 is equal to the predetermined speed or more, the braking force is applied to a turning outer wheel of the rear wheels 3 and 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the technical field of a vehicle attitude control device for controlling the attitude of a vehicle by controlling the operation of a brake unit that applies a braking force independently to left and right wheels. .

[0002]

2. Description of the Related Art Conventionally, various control devices for stabilizing the attitude of a vehicle have been known. For example, an anti-lock brake device has been used as a device for performing braking control. This anti-lock brake device prevents a locked or skid state of wheels from occurring during braking. A traction control device is used as a control device when the vehicle is accelerating. This traction control device enhances the acceleration and stability of the vehicle by appropriately adjusting the engine output so that the slip ratio of the drive wheels to the road surface does not become excessive. Further, there is known an attitude control device that controls an attitude of a vehicle while avoiding an unstable state due to a side slip or the like during traveling. This attitude control device individually controls the braking forces of the four wheels so that the actual attitude of the vehicle matches the target attitude, for example, when the vehicle is turning, and gives a moment to the vehicle in a stable direction with respect to the center of gravity of the vehicle. do it,
This is to enhance the stability of the vehicle.

[0003]

By the way, when the vehicle is turning (especially during a high G turn where a considerable lateral acceleration occurs in the vehicle), if the operation of depressing the accelerator pedal is performed, the vehicle moves backward. The load movement of the front wheel lowers the ground contact load on the front wheels, resulting in understeer characteristics and easy drift-out. Conversely, if the operation of returning the accelerator pedal suddenly during turning is performed, the rear wheel contact load decreases due to the forward load movement, resulting in oversteer characteristics.
Easy to spin. Since the under or oversteer characteristic caused by the operation of the accelerator pedal is a factor that makes the posture of the vehicle unstable, it is desirable to minimize such characteristic as much as possible. It is conceivable to cancel the under or oversteer characteristics using a conventional attitude control device.

However, in the above-described conventional attitude control apparatus, when the driver cannot control the attitude of the vehicle because the vehicle drifts out or spins, the control intervention is performed. It is difficult to negate the under or oversteer characteristics in a state where no slippage occurs.

[0005] The present invention has been made in view of such a point, and an object of the present invention is to eliminate under or oversteer characteristics caused by operation of an accelerator pedal during turning to prevent drift out and spin. And to improve accelerator controllability.

[0006]

In order to achieve the above object, according to the present invention, when a vehicle is in a turning state and an accelerator pedal depressing operation speed is equal to or higher than a predetermined speed, turning of the left and right wheels is performed. By applying a braking force to the inner wheel, the posture of the vehicle is controlled, or when the vehicle is in a turning state and the accelerator pedal return operation speed is equal to or higher than the set speed, the left or right wheel is turned to the turning outer wheel. By applying a braking force, the posture of the vehicle is controlled.

More specifically, according to the first aspect of the present invention, a brake unit for independently applying a braking force to left and right wheels of a vehicle, and a control for controlling the operation of the brake unit to control the attitude of the vehicle. And a vehicle attitude control device provided with the means.

The vehicle further comprises turning state determining means for determining whether or not the vehicle is in a turning state, and depressing operation speed detecting means for detecting a depressing operation speed of an accelerator pedal of the vehicle. When the turning state determining means determines that the vehicle is in a turning state and the depressing operation speed detected by the depressing operation speed detecting means is equal to or higher than a predetermined speed, a braking force is applied to the turning inner wheel among the left and right wheels. It is assumed that the configuration is such that the attitude of the vehicle is controlled by the provision.

According to the above configuration, when it is determined that the vehicle is in a turning state and the operation speed of the accelerator pedal is equal to or higher than a predetermined speed, the front wheel contact load decreases due to the operation of the accelerator pedal, resulting in understeer. The characteristic is canceled out by applying the braking force to the turning inner wheel, and the turning property is improved. In this case, there is a certain time lag between the depression of the accelerator pedal and the change in the behavior of the vehicle in response to the depression, and the braking force is immediately applied to the turning inner wheel after detecting the depression operation speed equal to or higher than a predetermined speed. Therefore, the understeer characteristic can be canceled before the vehicle drifts out, and the accelerator controllability at the time of turning can be improved.

According to a second aspect of the present invention, in the first aspect of the present invention, there is provided a return operation speed detecting means for detecting a return operation speed of the accelerator pedal of the vehicle, and the control means controls the vehicle to be turned by the turning state determination means. When it is determined that there is a vehicle and the return operation speed detected by the return operation speed detecting means is equal to or higher than the set speed, the posture of the vehicle is controlled by applying a braking force to the turning outer wheel of the left and right wheels. It shall be configured.

Thus, if the vehicle is determined to be in a turning state and the accelerator pedal return operation speed is equal to or higher than the set speed, the rear wheel contact load is reduced due to the accelerator pedal return operation, resulting in an overrun. The application of the braking force to the turning outer wheel cancels out the characteristic of the steering characteristic, thereby preventing the spin from occurring.

According to a third aspect of the present invention, in the second aspect of the present invention, an upper limit value is set for the braking force applied to the turning inner wheel and the outer wheel, and the upper limit value of the braking force applied to the turning outer wheel is determined. It is assumed that the braking force is set to be larger than the upper limit value of the braking force applied to the inner wheel.

By doing so, by setting the upper limit of the braking force applied to the turning inner wheel relatively small, it is possible to prevent a large braking force from being applied to the wheels during acceleration. At the same time, oversteer characteristics tend to occur particularly during high-G turning, so by setting the upper limit of the braking force applied to the turning outer wheel relatively large,
Spin can be reliably prevented.

According to a fourth aspect of the present invention, there is provided a brake unit for independently applying a braking force to left and right wheels of a vehicle, and control means for controlling the operation of the brake unit to control the attitude of the vehicle. For vehicle attitude control devices,
Turning state determining means for determining whether or not the vehicle is in a turning state; and returning operation speed detecting means for detecting a returning operation speed of an accelerator pedal of the vehicle, wherein the control means includes the turning state determining means. When it is determined that the vehicle is in a turning state and the return operation speed detected by the return operation speed detection means is equal to or higher than a set speed, by applying a braking force to the turning outer wheel of the left and right wheels, It is assumed that it is configured to control the attitude of the vehicle.

Thus, the oversteer characteristic can be canceled before the vehicle spins, and the accelerator controllability at the time of turning can be improved as in the first aspect of the invention.

According to a fifth aspect of the present invention, in the first or fourth aspect of the invention, the turning state determining means has a lateral acceleration detecting means for detecting a lateral acceleration generated in the vehicle. When the detected lateral acceleration is equal to or greater than a predetermined threshold, the vehicle is determined to be in a turning state. According to a sixth aspect of the present invention, in the fifth aspect of the invention, the control means controls the attitude of the vehicle only when the vehicle is traveling on a high μ road having a friction coefficient equal to or more than a predetermined value. It shall be configured. According to these inventions, the function and effect of the invention of claim 1 or 4 can be effectively exhibited.

According to a seventh aspect of the present invention, in the fifth aspect of the present invention, the braking force is a predetermined constant value. Thus, unlike feedback control, there is no delay in control, so that drift-out and spin can be reliably prevented.

According to an eighth aspect of the present invention, in the fifth aspect of the invention, the braking force is proportional to the operation speed of the accelerator pedal.

By doing so, the same operation and effect as the invention of claim 7 can be obtained, and the more the operating speed of the accelerator pedal becomes, the more the understeer or oversteer characteristics become, so that a more appropriate braking force is applied. Can be.

According to a ninth aspect of the present invention, in the fifth aspect of the present invention, the control means is configured to apply a predetermined magnitude of braking force at a timing when the behavior of the vehicle changes in response to the operation of the accelerator pedal. It is assumed that

Thus, it is possible to prevent the driver from feeling uncomfortable with the control while satisfactorily canceling the under or oversteer characteristics caused by the operation of the accelerator pedal during turning.

According to a tenth aspect of the present invention, in the fifth aspect of the present invention, the control means is configured to control the attitude of the vehicle only when the vehicle speed is equal to or higher than a predetermined vehicle speed. As a result, lateral acceleration may occur at low speed due to wheel trip or the like, so that control can be prevented in such a case.

According to an eleventh aspect of the present invention, in the first or the fourth aspect of the present invention, the control means is configured to control the braking force when the braking force is applied to the wheel on the side opposite to the wheel to which the braking force is to be applied. Before applying braking force to the wheels to which
The posture of the vehicle is controlled by controlling the release of the braking force for the opposite wheel.

According to the present invention, when a braking force is to be applied during a turn in the opposite direction to the previous turn before the braking force applied during the previous turn becomes zero, such as during slalom running, both left and right wheels are used. To prevent the driver from feeling deceleration or discomfort by applying a braking force to the driver. The effect is obtained.

According to a twelfth aspect of the present invention, in the first or fourth aspect of the present invention, an upper limit value is set for the braking force, and the control means controls a friction coefficient of a road surface on which the vehicle is traveling, a vehicle speed of the vehicle, It is assumed that the upper limit of the braking force is corrected in accordance with one of the steering angle and the wheel slip amount. This makes it possible to perform more appropriate control while preventing the driver from feeling uncomfortable.

According to a thirteenth aspect, in the first or fourth aspect, the control means is configured to correct the braking force according to the steering angle of the vehicle.

With this, the change in the behavior of the vehicle increases as the steering angle increases. Therefore, by increasing the braking force in accordance with the steering angle, drift-out and spin can be reliably prevented.

[0028]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an overall configuration of a vehicle attitude control device according to an embodiment of the present invention. This attitude control device is independent of each of a left front wheel 1, a right front wheel 2, a left rear wheel 3, and a right rear wheel 4. Brake unit 10 for applying braking force
And a controller 50 as control means for controlling the operation of the brake unit 10 to control the attitude of the vehicle.

The left and right front wheels 1 and 2 are driven wheels.
The left and right rear wheels 3 and 4 are drive wheels, and the output torque of the engine 31 is controlled by the automatic transmission 32, the propeller shaft 33,
Differential mechanism 34 and left and right drive shafts 35 and 36
Through the rear wheels 3 and 4.

The brake unit 10 has wheels 1 to
4 has brakes 11 to 14 respectively provided. The brakes 11 to 14 supply disks 11 a to 14 a which rotate integrally with the wheels 1 to 4 and supply of brake fluid pressure (braking pressure). And calipers 11b to 14b for receiving and braking the disks 11a to 14a. The configuration for supplying the brake fluid pressure is as follows.

That is, there is provided a booster 18 for increasing the depressing force of the brake pedal 17 by the driver, and a master cylinder 19 for generating a braking pressure in accordance with the force increased by the booster 18. The brake pedal 17 is provided with a brake sensor 51 that detects the depression operation of the brake pedal 17 and outputs an ON signal. The ON signal from the brake sensor 51 is input to the controller 50.

From the master cylinder 19, brake pressure supply lines 20 and 21 for front wheels and rear wheels extend respectively. The front wheel brake pressure supply line 20 includes a left front wheel brake pressure supply line 20a and a right front wheel brake pressure supply line 2
0b, and are connected to the calipers 11b and 12b of the brakes 11 and 12 of the left and right front wheels 1 and 2, respectively. The left front wheel brake pressure supply line 20a is provided with a first valve unit 25 including an electromagnetic on-off valve 25a and an electromagnetic relief valve 25b, and the right front wheel brake pressure supply line 20b is provided with an electromagnetic open / close valve. A second valve unit 26 including a valve 26a and an electromagnetic relief valve 26b is provided. In addition, the rear wheel braking pressure supply line 2
Reference numeral 1 branches to a left rear wheel braking pressure supply line 21a and a right rear wheel braking pressure supply line 21b.
Calipers 13b and 14 of brakes 13 and 14 at 4
b. Above left rear wheel brake pressure supply line 2
1a has an electromagnetic on-off valve 27a and an electromagnetic relief valve 27
b is provided on the right rear wheel braking pressure supply line 21b.
A fourth valve unit 28 including an electromagnetic relief valve 8a and an electromagnetic relief valve 28b is provided.

The controller 50 controls the first to fourth valve units 25 to 28 to adjust the braking pressures of the brakes 11 to 14 of the respective wheels 1 to 4 independently of each other. When an ON signal from the brake sensor 51 is input to the controller 50, brake control such as ABS control is performed.

In the intake passage 41 of the engine 31,
A throttle valve 42 connected to an accelerator pedal 45 is provided. The opening of the throttle valve 42 is detected by a throttle opening sensor 52, and the detection signal of the throttle opening sensor 52 is differentiated to obtain the controller 5.
0 is input. In other words, the throttle opening sensor 52 constitutes a depression operation speed detection unit that detects the depression operation speed of the accelerator pedal 45, and a return operation speed detection unit that detects the return operation speed of the accelerator pedal 45.

The controller 50 has a signal from a lateral acceleration sensor 53 as a lateral acceleration detecting means for detecting a lateral acceleration generated in the vehicle, and wheel speed sensors 54 to 54 for detecting the rotational speed of each of the wheels 1-4. 57, a signal from a vehicle speed sensor 58 for detecting the speed of the vehicle, and a signal from a steering angle sensor 59 for detecting the steering angle of the steering wheel. A signal from the lateral acceleration sensor 53 is sent to a turning state determination unit 50a in the controller 50.
The turning state determination unit 50a determines whether the vehicle is in a turning state, that is, the lateral acceleration detected by the lateral acceleration sensor 53 (in this embodiment, when the vehicle is turning left, When the right turn is made negative, the vehicle is determined to be in a turning state when the lateral acceleration is an absolute value or more. Thus, the turning state determining unit 50a constitutes turning state determining means for determining whether or not the vehicle is in a turning state, has lateral acceleration detecting means, and is detected by the lateral acceleration detecting means. When the lateral acceleration is equal to or greater than the predetermined threshold, the vehicle is determined to be in a turning state.

When the turning state determining unit 50a determines that the vehicle is in a turning state, and when the operation speed of the accelerator pedal 45 detected by the throttle opening sensor 52 is equal to or higher than a predetermined speed, the controller 50 determines whether the vehicle is in a turning state. By applying a braking force to the turning inner wheel of the left and right rear wheels 3 and 4, the vehicle is controlled in attitude. When the turning state determination unit 50a detects that the vehicle is turning and the return operation speed of the accelerator pedal 45 detected by the throttle opening sensor 52 is equal to or higher than the set speed, The posture of the vehicle is controlled by applying a braking force to the outer turning wheel of the left and right rear wheels 3 and 4. The predetermined threshold value for the turning state determination is set to a value (0.4 G in this embodiment) that is generated only when the vehicle is traveling on a high μ road where the friction coefficient is equal to or more than the predetermined value. I have. That is, the controller 5
0 is configured to control the attitude of the vehicle only when the vehicle is traveling on a high μ road where the friction coefficient is equal to or more than a predetermined value.

The specific control processing operation of the controller 50 for controlling the vehicle attitude is performed as shown in FIGS. That is, in the first step S1, it is determined whether or not the lateral acceleration detected by the lateral acceleration sensor 53 in the turning state determination unit 50a is 0.4 G or more. That is, it is determined whether or not the lateral acceleration is a left turn of 0.4 G or more. If this determination is NO, step S1
5 (see FIG. 4), while if the determination is YES (when the turning state determination unit 50a determines that the vehicle is in a left turning state), the flow proceeds to step S2.

In step S2, the accelerator pedal 4
It is determined whether or not the depressing operation speed of No. 5 (opening speed of the throttle valve 42) is equal to or higher than a predetermined speed th1 (for example, 15% / s in terms of the opening speed of the throttle valve 42). If this determination is NO, While the process proceeds to step S8 (see FIG. 3), if the determination is YES, the process proceeds to step S3 to determine whether the target brake fluid pressure value of the right rear wheel 4 (referred to as a right rear wheel target fluid pressure value) is zero. Is determined.

When the determination in step S3 is YES, the process proceeds to step S4 in which the target brake hydraulic pressure value of the left rear wheel 3 (referred to as the left rear wheel target hydraulic pressure value) is calculated by adding the left rear wheel target hydraulic pressure value to (Depressing operation speed-th1) -gain1 is updated to the value of gain3, and in the next step S5, the target rear left wheel pressure value is set to the upper limit value max1.
It is determined whether or not this is the case. If the determination in step S5 is NO, the process returns to step S2,
If the determination in step S5 is YES, the process proceeds to step S6, where the left rear wheel target hydraulic pressure value is set to the upper limit value max1, and the process returns.

That is, when the depressing operation speed of the accelerator pedal 45 becomes equal to or higher than the predetermined speed th1 when the lateral acceleration is 0.4 G or more in the left turn, if the right rear wheel target hydraulic pressure value is 0, the left inner wheel which is the turning inner wheel is used. A braking force (braking pressure) is applied to the rear wheel 3, and the understeer characteristic is canceled by the braking force, where the front wheel 1 and the ground contact load decrease due to the depression operation of the accelerator pedal 45. . The braking force is proportional to the operation speed of the accelerator pedal 45, and the value of gain1, which is a proportionality constant (gain), is set to a predetermined value at a timing when the behavior of the vehicle changes in response to the operation of the accelerator pedal 45. It is set so that the braking force can be obtained. In other words, after the operation of the accelerator pedal 45 is performed, until the rotation speed of the engine 31 increases and the driving force is transmitted to the left and right rear wheels 3 and 4 and the behavior of the vehicle changes, the vehicle specifications are changed. There is a time lag specific to the determined vehicle, and the braking force is applied by delaying the time lag. In addition, open control is used instead of feedback control.

If an excessively large braking force is applied, the braking force gives the driver a sense of deceleration when trying to accelerate, so the upper limit value max1 is provided.
It is desirable that the upper limit value max1 be corrected in accordance with any of the friction coefficient of the road surface on which the vehicle is traveling, the vehicle speed of the vehicle, the steering angle of the steering wheel, and the slip amount (slip ratio) of the wheels 1-4. In other words, the upper limit value max1 is increased because the lower the coefficient of friction, the more likely it is to have understeer characteristics.
The larger the vehicle speed, the steering angle of the steering wheel and the amount of wheel slip, the larger the value.

On the other hand, if the determination in step S3 is NO, the process proceeds to step S7, in which the right rear wheel target hydraulic pressure value is calculated by subtracting the right rear wheel target hydraulic pressure value- (depressing operation speed-th1).
Update to gain1 and return.

That is, the right rear wheel 4 (the wheel on the opposite side to the wheel (left rear wheel 3) to which the braking force is applied) to which the braking force has been applied during the previous right turn as in slalom running. When the braking force is not zero and the braking force is applied to the right rear wheel 4, the braking force is removed from the right rear wheel 4 before the braking force is applied to the left rear wheel 3. To cancel the understeer characteristics. The amount by which the braking force is removed is proportional to the operation speed of the accelerator pedal 45, similarly to the application of the braking force to the left rear wheel 3, and the proportionality constant (gain) is gain1 as described above. When the braking force of the right rear wheel 4 becomes zero, the braking force is applied to the left rear wheel 3 as described above.

In step S8, the accelerator pedal 4
It is determined whether the depressing operation speed of No. 5 is equal to or lower than th2 (for example, -15% / s in terms of the opening speed of the throttle valve 42). This value of th2 is a negative value, and therefore, this determination is the same as the determination as to whether or not the return operation speed of the accelerator pedal 45 (closing speed of the throttle valve 42) is equal to or higher than the set speed (-th2). Will be.

If the determination in step S8 is NO, the process proceeds to step S14, while if the determination is YES, the process proceeds to step S9 to determine whether the left rear wheel target hydraulic pressure value is zero. .

When the determination in step S9 is YES, the process proceeds to step S10, in which the right rear wheel target hydraulic pressure value is calculated by subtracting the right rear wheel target hydraulic pressure value + (th2−stepping operation speed).
Update to gain2 and change the value of gain to gai
n4 (smaller than gain3 in step S4), and in a next step S11, it is determined whether or not the right rear wheel target hydraulic pressure value is equal to or more than an upper limit value max2. If the determination in step S11 is NO, the process returns to step S2, while if the determination in step S11 is YES, the process proceeds to step S12, where the right rear wheel target hydraulic pressure value is set to the upper limit value max2 and the process returns. I do.

That is, when the return operation speed of the accelerator pedal 45 becomes equal to or higher than the set speed at the time of the left turn at the lateral acceleration of 0.4 G or more, if the target hydraulic pressure value of the left rear wheel is 0, the right rear wheel which is the turning outer wheel is provided. When the braking force is applied to the wheel 4 and the rear wheel 3 and the ground contact load decrease due to the return operation of the accelerator pedal 45, the oversteering characteristic is canceled by the braking force, where the oversteering characteristic is canceled. This braking force is also proportional to the operation speed of the accelerator pedal 45 as in the case of the acceleration, and the proportional constant (gain) g
The value of “ain2” is also set so that a braking force of a predetermined magnitude is obtained at the timing when the behavior of the vehicle changes in response to the operation of the accelerator pedal 45 (may be the same value as “gain1”).

Similarly to the upper limit value max1, the upper limit value max2 is corrected according to any of the friction coefficient of the road surface on which the vehicle is traveling, the vehicle speed of the vehicle, the steering angle of the steering wheel, and the slip amount of the wheels. It is desirable. That is, the upper limit value max2 also increases as the friction coefficient decreases, and the vehicle speed,
The larger the steering angle and the amount of wheel slip, the larger the setting. Even if the upper limit value max2 is increased to some extent, the driver does not feel uncomfortable as in the case of the acceleration described above, and particularly tends to have an oversteer characteristic during a high-G turn. Therefore, the upper limit value max2 is preferably set to be larger than the upper limit value max1.

On the other hand, if the determination in step S9 is NO, the process proceeds to step S13 to update the left rear wheel target hydraulic pressure value to the left rear wheel target hydraulic pressure value-(th2-depressing operation speed) gain2. And return. This control is the same as in step S7.

In step S14, the left rear wheel target hydraulic pressure value is updated to the left rear wheel target hydraulic pressure value -gain.
The right rear wheel target hydraulic pressure value is updated to the right rear wheel target hydraulic pressure value -gain, and the routine returns. That is, when the operation speed of the accelerator pedal 45 becomes slow, the braking force of the left rear wheel 3 or the right rear wheel 4 is gradually released. In this case, in order to prevent the posture of the vehicle from becoming unstable, the amount of release of the braking force of the right rear wheel 4 is made smaller than that of the left rear wheel 3.

In the step S15, the lateral acceleration becomes-
It is determined whether it is 0.4 G or less. That is, it is determined whether or not the lateral acceleration is a right turn of 0.4 G or more. When this determination is NO, the process proceeds to step S28 (see FIG. 5), while when the determination is YES (when the turning state determination unit 50a determines that the vehicle is in the right turning state), the process proceeds to step S28. Proceed to S16.

In step S16, it is determined whether or not the stepping speed of the accelerator pedal 45 is greater than th1. If the determination is NO, step S22 is performed.
On the other hand, when the determination is YES, the process proceeds to step S17 to determine whether or not the left rear wheel target hydraulic pressure value is zero.

If the determination in step S17 is YES, the process proceeds to step S18, in which the right rear wheel target hydraulic pressure value is calculated by subtracting the right rear wheel target hydraulic pressure value + (depressing operation speed-th1).
Update to gain1 and change the value of gain to gai
It is set to n3, and in the next step S19, it is determined whether or not the right rear wheel target hydraulic pressure value is equal to or more than the upper limit value max1. If the determination in step S19 is NO, the process returns to step S16, while the determination in step S19 is YES.
In step S20, the process proceeds to step S20, where the right rear wheel target hydraulic pressure value is set to the upper limit value max1, and the process returns.

On the other hand, if the determination in step S17 is NO, the process proceeds to step S21, in which the left rear wheel target hydraulic pressure value is reduced to the left rear wheel target hydraulic pressure value− (depressing operation speed−th
1) Update to gain1 and return.

In step S22, it is determined whether or not the operation speed of the accelerator pedal 45 is less than th2.
If the determination in step S22 is NO, the process proceeds to step S28, while the determination in step S22 is YES.
In step S23, the process proceeds to step S23 to determine whether or not the right rear wheel target hydraulic pressure value is zero.

If the determination in step S23 is YES, the process proceeds to step S24, in which the target left rear wheel hydraulic pressure value is calculated by subtracting the target rear left wheel hydraulic pressure value + (th2−the depressing operation speed).
Update to gain2 and change the value of gain to gai
In step S25, it is determined whether or not the left rear wheel target hydraulic pressure value is equal to or more than the upper limit value max2. If the determination in step S25 is NO, the process returns to step S16, while the determination in step S25 is YES.
In step S26, the process proceeds to step S26, where the left rear wheel target hydraulic pressure value is set to the upper limit value max2, and the routine returns.

On the other hand, if the determination in step S23 is NO, the process proceeds to step S27 to update the right rear wheel target hydraulic pressure value to the right rear wheel target hydraulic pressure value-(th2-depressing operation speed) gain2. And return.

In step S28, step S14
Similarly to the left rear wheel target hydraulic pressure value, the left rear wheel target hydraulic pressure value-g
ain, the right rear wheel target hydraulic pressure value is updated to the right rear wheel target hydraulic pressure value -gain, and the process returns.

That is, the same control as in the left turn is performed during the right turn, and if the lateral acceleration is 0.4 G or more and the depressing operation speed of the accelerator pedal 45 is a predetermined speed or more, the inner wheel is the turning inner wheel. A braking force is applied to the right rear wheel 4 to cancel the understeer characteristic, and the lateral acceleration becomes 0.
If the speed is greater than or equal to 4 G and the speed at which the accelerator pedal 45 is returned is greater than or equal to the set speed, a braking force is applied to the left rear wheel 3, which is the turning outer wheel, and the oversteer characteristic is canceled.

Incidentally, as shown in FIG.
When the right rear wheel target hydraulic pressure value obtained in steps S7, S10 and the like becomes 0 or less (when the determination in step S41 is YES), the right rear wheel target hydraulic pressure value is set to 0 (step S4).
2) When the right rear wheel target hydraulic pressure value is larger than 0 (when the determination in step S41 is NO), the right rear wheel target hydraulic pressure value is set to the obtained value. Similarly, as shown in FIG. 7, when the left rear wheel target hydraulic pressure value obtained in steps S4, S13, and the like becomes 0 or less (when the determination in step S51 is YES), the left side wheel is left. Set the rear wheel target hydraulic pressure to 0
(Step S52), and when the left rear wheel target hydraulic pressure value is larger than 0 (when the determination in step S51 is NO), the left rear wheel target hydraulic pressure value is set to the obtained value. .

Therefore, in the above-described embodiment, when the depressing operation speed of the accelerator pedal 45 becomes a predetermined speed or more when the lateral acceleration is 0.4 G or more, the left and right rear wheels 3
Since a braking force having a magnitude proportional to the operation speed of the accelerator pedal 45 is applied to the turning inner wheel of 4, the understeer characteristic caused by the operation of depressing the accelerator pedal 45 can be canceled to prevent drift out. When the return operation speed of the accelerator pedal 45 is equal to or higher than the set speed, a braking force having a magnitude proportional to the return operation speed of the accelerator pedal 45 is applied to the outer turning wheel of the left and right rear wheels 3 and 4. Thus, the oversteer characteristic caused by the returning operation of the accelerator pedal 45 can be canceled to prevent the spin from occurring. Moreover, the timing of the application of the braking force is substantially the same as the timing at which the behavior of the vehicle changes in response to the operation of the accelerator pedal 45, so that the driver can feel uncomfortable in the control while satisfactorily canceling the under or oversteer characteristics. Giving can be prevented. In addition, since the open control is used, unlike the feedback control, there is no delay in the control, so that the braking force can be applied in time for the change in the behavior of the vehicle, and the driver does not feel uncomfortable. Thus, drift-out and spin can be reliably prevented.

Note that the gain (gain1 or gain1)
2) is desirably changed according to the vehicle speed and the shift position of the automatic transmission 32. For example, as shown in FIG. 8, the maximum is set in a middle speed region where a lot of sports running is performed, and smaller in a high speed region than in a middle speed region. In the low-speed region, it is set to zero. That is, when the vehicle speed is a predetermined vehicle speed (for example, 20 km
/ H) Only when the vehicle speed is equal to or greater than that, the posture of the vehicle is controlled to prevent the control from being performed even when lateral acceleration occurs due to the stumbling of the wheels 1 to 4 at a low speed. The gain is set to be smaller when the shift position of the automatic transmission 32 is in the high-speed gear than in the low-speed gear. this is,
This is because the time from the operation of the accelerator pedal 45 to the change in the behavior of the vehicle at the time of the high-speed gear is longer than at the time of the low-speed gear.

It is desirable that the gain be smaller when the steering wheel is turned, in which the posture of the vehicle becomes particularly unstable, than when the steering wheel is turned back. Then, during slalom driving (determined by the steering wheel angular velocity),
Even at the time of cutting back, it is preferable to make the size as small as that at the time of cutting. Further, it is preferable that the gain is set to be larger as the lateral acceleration is larger.

Further, in the above-described embodiment, the braking force having a magnitude proportional to the operation speed of the accelerator pedal 45 is applied to the turning inner wheel or the turning outer wheel, but the braking force is controlled regardless of the operation speed of the accelerator pedal 45. The power may be a constant value.

Also, the braking force is applied only to the rear wheel among the front and rear wheels of the turning inner wheel or the outer turning wheel. However, the braking force is applied to only the front wheel or both of the front and rear wheels of the turning inner wheel or the outer turning wheel. It may be. When the braking force is applied to both the front and rear wheels of the turning inner wheel or the turning outer wheel, the brake unit 10 does not need to apply the braking force to each of the wheels 1 to 4 independently. What is necessary is just to apply the braking force independently to the wheels 1 and 3 and the right wheels 2 and 4.

In addition, in the above embodiment, the front wheels 1 and 2 are driven wheels, and the rear wheels 3 and 4 are drive wheels. Conversely, the front wheels 1 and 2 are drive wheels and the rear wheels 3 , 4 as driven wheels, the present invention can be applied.
4 may be a driving wheel.

[0067]

As described above, in the vehicle attitude control apparatus of the present invention, when it is determined that the vehicle is in a turning state and the accelerator pedal depressing operation speed is equal to or higher than the predetermined speed, the left and right wheels are turned off. The attitude of the vehicle is controlled by applying a braking force to the inner wheels of the vehicle. Further, in another vehicle posture control device of the present invention, when it is determined that the vehicle is in a turning state and the return operation speed of the accelerator pedal is equal to or higher than the set speed, the braking force is applied to the turning outer wheel of the left and right wheels. By giving, the attitude of the vehicle is controlled. Therefore, according to these attitude control devices, under or oversteer characteristics caused by operation of the accelerator pedal during turning can be counteracted, drift-out and spin can be prevented, and accelerator controllability can be improved. .

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram showing a vehicle attitude control device according to an embodiment of the present invention.

FIG. 2 is a flowchart showing a control processing operation by a controller.

FIG. 3 is a flowchart continued from a part of the flowchart of FIG. 2;

FIG. 4 is a flowchart continued from a part of the flowchart of FIG. 2;

FIG. 5 is a flowchart continued from a part of the flowchart of FIG. 4;

FIG. 6 is a flowchart illustrating a lower limit setting process of a right rear wheel target hydraulic pressure value.

FIG. 7 is a flowchart illustrating a lower limit setting process of a left rear wheel target hydraulic pressure value.

FIG. 8 is a characteristic diagram showing an example of a change of a gain with respect to a vehicle speed.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Left front wheel 2 Right front wheel 3 Left rear wheel 4 Right rear wheel 10 Brake unit 45 Accelerator pedal 50 Controller (control means) 50a Turning state determination unit (turning state determination means) 52 Throttle opening sensor (stepping operation speed detection means) ( Return operation speed detecting means) 53 Lateral acceleration sensor (lateral acceleration detecting means)

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Haruki Okazaki 3-1 Shinchi, Fuchu-cho, Aki-gun, Hiroshima Mazda Co., Ltd. (72) Inventor Masaji Oda 3-1 Shinchi, Fuchu-cho, Aki-gun, Hiroshima Mazda Co., Ltd. F-term (reference) 3D046 BB21 FF09 HH02 HH05 HH08 HH22 HH25 HH36 HH46 JJ01 JJ05 JJ06 KK08 LL23 LL30

Claims (13)

[Claims] 1. A vehicle attitude control device comprising: a brake unit for independently applying a braking force to left and right wheels of a vehicle; and control means for controlling the operation of the brake unit to control the attitude of the vehicle. And a turning state determining means for determining whether or not the vehicle is in a turning state; and a depressing operation speed detecting means for detecting a depressing operation speed of an accelerator pedal of the vehicle. When the turning state determining means determines that the vehicle is in a turning state and the depressing operation speed detected by the depressing operation speed detecting means is equal to or higher than a predetermined speed, a braking force is applied to the turning inner wheel of the left and right wheels. A vehicle attitude control device configured to control the attitude of the vehicle. 2. The vehicle attitude control device according to claim 1, further comprising return operation speed detection means for detecting a return operation speed of an accelerator pedal of the vehicle, wherein the control means sets the vehicle in a turning state by turning state determination means. When it is determined that there is, and the return operation speed detected by the return operation speed detection means is equal to or higher than the set speed,
By applying braking force to the turning outer wheel of the left and right wheels,
An attitude control device for a vehicle, which is configured to control the attitude of the vehicle. 3. The attitude control device for a vehicle according to claim 2, wherein upper limits are set for the braking force applied to the turning inner wheel and the outer wheel, respectively, and the upper limit value of the braking force applied to the turning outer wheel is turned. An attitude control device for a vehicle, wherein the attitude control device is set to be larger than an upper limit value of a braking force applied to an inner wheel. 4. A vehicle attitude control device comprising: a brake unit for independently applying a braking force to left and right wheels of a vehicle; and control means for controlling the operation of the brake unit to control the attitude of the vehicle. And a turning state determining means for determining whether or not the vehicle is in a turning state; and a return operation speed detecting means for detecting a return operation speed of an accelerator pedal of the vehicle. When the turning state determination unit determines that the vehicle is in a turning state and the return operation speed detected by the return operation speed detection unit is equal to or higher than a set speed, a braking force is applied to the turning outer wheel of the left and right wheels. A vehicle attitude control device configured to control the attitude of the vehicle. 5. The attitude control device for a vehicle according to claim 1, wherein the turning state determining means includes a lateral acceleration detecting means for detecting a lateral acceleration generated in the vehicle. An attitude control device for a vehicle, wherein the attitude control apparatus is configured to determine that the vehicle is in a turning state when the detected lateral acceleration is equal to or greater than a predetermined threshold. 6. The vehicle attitude control device according to claim 5, wherein the control means controls the vehicle attitude only when the vehicle is traveling on a high μ road having a friction coefficient equal to or more than a predetermined value. An attitude control device for a vehicle, comprising: 7. The vehicle attitude control device according to claim 5, wherein the braking force is a predetermined constant value. 8. The vehicle attitude control device according to claim 5, wherein the braking force is proportional to an operation speed of an accelerator pedal. 9. The vehicle attitude control device according to claim 5, wherein the control means is configured to apply a predetermined amount of braking force at a timing at which a change in the behavior of the vehicle occurs in response to the operation of the accelerator pedal. An attitude control device for a vehicle, comprising: 10. The vehicle attitude control device according to claim 5, wherein the control means is configured to control the attitude of the vehicle only when the vehicle speed of the vehicle is equal to or higher than a predetermined vehicle speed. Vehicle attitude control device. 11. The vehicle attitude control device according to claim 1, wherein the control means is configured to control the braking force when a braking force is applied to a wheel on a side opposite to a wheel to which the braking force is to be applied. A vehicle configured to control a posture of the vehicle by performing a braking force release control on the opposite wheel before applying a braking force to a wheel to which the vehicle is to be applied. Attitude control device. 12. The attitude control device for a vehicle according to claim 1, wherein an upper limit value is set for the braking force, and the control means includes a coefficient of friction of a road surface on which the vehicle is traveling, a vehicle speed of the vehicle, An attitude control device for a vehicle, wherein the upper limit value of the braking force is corrected in accordance with one of a steering angle and a wheel slip amount. 13. The vehicle attitude control device according to claim 1, wherein the control means is configured to correct a braking force according to a steering angle of the vehicle. Control device.