JP3125659B2 - Suspension control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a suspension control device, and more particularly to a suspension control device for variably controlling a damping force of a suspension mechanism.

[0002]

2. Description of the Related Art Conventionally, there is a suspension control device which variably controls a damping force of a suspension mechanism provided between a vehicle body and an axle support member. For example, Japanese Unexamined Patent Application Publication No.
No. 76806 discloses a sprung acceleration, estimates a relative speed between a sprung member and an unsprung member from the sprung acceleration, and uses this and a sprung speed obtained from the sprung acceleration. Discloses that the control amount of the damping force is controlled by the skyhook theory.

[0003]

In the conventional apparatus, the relative speed between the sprung member and the unsprung member is estimated from the sprung acceleration. The observer model that makes this estimation is designed for straight running, and not for turning.

For this reason, during turning, the relative speed between the sprung member and the unsprung member estimated from the sprung acceleration becomes an erroneous value, whereby the control amount of the damping force obtained by the skyhook control becomes erroneous. There was a problem that would be. The present invention has been made in view of the above points, and provides a suspension control device that prevents an erroneous damping force control amount during turning by correcting a damping force control amount based on the skyhook theory during turning. Aim.

[0005]

According to the present invention, as shown in FIG. 1, the relative speed between the sprung member and the unsprung member is estimated from the sprung acceleration detected by the acceleration detecting means M1, Using this and the sprung speed obtained from the sprung acceleration, the suspension mechanism M
In the suspension control device having the skyhook control means M2 for controlling the damping force of No. 5, the steering angle detecting means M3 for detecting the steering angle, and the damping force according to the skyhook theory at the time of turning from the detected steering angle are corrected. value
Is used as a control amount for skyhook control .

For this reason, even if the estimated value of the relative speed between the sprung member and the unsprung member is incorrect when turning, and the control amount of the damping force is wrong , the corrected value of the damping force is used as the control amount.
Since it is used for hook control, erroneous control of the damping force during turning can be prevented. According to a second aspect of the present invention, in the suspension control device according to the first aspect, there is provided a vehicle speed detecting means for detecting a vehicle speed, and the control amount correcting means controls a value obtained by correcting a damping force according to the vehicle speed. Sky as quantity
Used for hook control .

For this reason, when turning, the damping force according to the vehicle speed is obtained.
The corrected value is used as a control amount in the skyhook control, and the control of the damping force according to the steering angle performed during turning and the control of the damping force according to the skyhook theory are performed without discomfort. Can be.

[0008]

FIG. 2 shows a functional block diagram of an embodiment of the present invention. In the figure, acceleration sensors 10 to 13 serving as acceleration detecting means M1 are provided on shock absorbers of four wheels of a vehicle, respectively, and detect sprung acceleration (vertical acceleration) of each of the four wheels to obtain an ECU (electronic control). (Control circuit) 20. The steering angle sensor 14 as the steering angle detecting means M3 detects the steering angle of the steering wheel and supplies the detected steering angle to the ECU 20. The vehicle speed sensor 15 detects the speed of the vehicle and supplies it to the ECU 20. The brake switch 16 is turned on by depressing a brake pedal, detects a brake operation, and supplies the brake operation to the ECU 20. The rotation angle sensor 17 detects the engine speed and supplies it to the ECU 20.

The ECU 20 is formed of, for example, a microcomputer and has a skyhook control function 21, a steering control function 22, a vehicle speed control function 23, an anti-dive control function 24, an anti-squat control function 25, and a maximum value selection function 26. ing. The skyhook control function 21 estimates the relative speed between the sprung member and the unsprung member by an observer for each wheel from the sprung acceleration of each of the four wheels detected by the acceleration sensors 10 to 13, and integrates the sprung acceleration. The sprung speeds are calculated from these values, the control amount of the damping force of the shock absorber of the skyhook control is calculated from these, and the control amount is corrected according to the vehicle speed at the time of turning, and the obtained control amount is used as the maximum value selection function 26. To supply.

The steering control function 22 calculates the steering speed by differentiating the steering angle, and calculates the control amount of the damping force of the shock absorber, which becomes harder as the steering speed becomes faster, in accordance with the steering speed. To supply. The vehicle speed control function 23 calculates the control amount of the damping force of the shock absorber, which becomes harder as the vehicle speed increases according to the vehicle speed, and supplies the control amount to the maximum value selection function 26.

The anti-dive control function 24 calculates the control amount of the damping force of the shock absorber that becomes hard when the brake switch is turned on, and the anti-squat control function 25 calculates the control amount of the shock absorber that becomes hard when the engine speed suddenly increases. The control amounts of the damping force are calculated, and the respective damping amounts are supplied to the maximum value selecting function 26. Maximum value selection function 2
6 selects the maximum value of the control amount of the damping force for each wheel, and uses this as the control amount of the shock absorber of each wheel. The ECU 20 drives each of the damping force switching actuators 30 to 33 of the shock absorber of each wheel based on the control amount of the damping force. FIG. 3 shows a flowchart of one embodiment of the skyhook control routine executed by the skyhook control function 21 of the ECU 20. This routine is repeatedly executed at predetermined time intervals. In FIG. 10, in step S10, the target control amount of the damping force of the shock absorber of the skyhook control is obtained from the relative speed between the sprung member and the unsprung member estimated from the sprung acceleration and the sprung speed obtained by integrating the sprung acceleration. Calculate MF. This target control amount MF is, for example, 1 to 2
Is an integer up to 0, the damping force is the softest at MF = 1,
It is the hardest when MF = 20. This step S10 corresponds to the skyhook control means M2.

In the next step S20, it is determined whether or not the target control amount MF is 1, that is, whether or not the damping force has been increased by the skyhook control. here,
If MF = 1 and there is no increase in the damping force due to the skyhook control, the process proceeds to step S30. On the other hand, if the damping force has been increased by the skyhook control at MF # 1, the process proceeds to step S40 and the steering angle θ detected by the steering sensor 14
Is substantially zero or not. Here, when the steering angle θ is not substantially 0, that is, at the time of turning, the process proceeds to step S50. In step S50, the vehicle speed SP detected by the vehicle speed sensor 15
The target control amount MF is calculated with reference to the map shown in FIG. Thereafter, in step S60, the correction flag Fla
After setting g to 1 to indicate that the target control amount MF has been corrected, the process proceeds to step S30.

In step S40, the steering angle θ is substantially zero.
If so, the process proceeds to step S70, and the correction flag Fla
It is determined whether g is 1 or not. Here, in the case of Flag # 1, the vehicle does not turn, and the process directly proceeds to step S30. If Flag = 1, that is, if the steering angle θ is substantially zero while the target control amount MF is being corrected, the process proceeds to step S80, where the correction flag Flag is set to 0.
Is set to 1 in the next step S90, and the process proceeds to step S30. Step S above
50 corresponds to the control amount correcting means M4.

In step S30, the target control amount MF calculated in step S10 or corrected in one of steps S50 and S90 is determined as the target control amount of the skyhook control. The respective routines of the vehicle speed control function 23, the anti-dive control function 24, the anti-square control function 25, and the maximum value selection function 26 are executed.

By the way, when the vehicle turns and the steering angle θ changes as shown in FIG. 5A, the steering speed (absolute value)
Changes as shown in FIG. 5 (B). The steering control function 22 calculates a target control amount shown in FIG. 5C based on the steering speed. In addition, the skyhook control function 21 calculates the target control amount MF having the value shown in FIG.

In the conventional device, a maximum value is selected from a target control amount by the steering control shown in FIG. 5C and a target control amount by the skyhook control shown in FIG. 5D. The result is as shown in FIG. However, the control in the period T ₁ is a skyhook control during turning, the control amount is likely to be erroneous.

On the other hand, in the present embodiment, during the turning shown in FIG.
The target control amount MF is corrected to 1 in accordance with the vehicle speed SPD, and when the steering angle θ is approximately 0, the target control amount MF is corrected to 1, and the target control amount MF is, for example, as shown in FIG. Become. The control of the periods T ₂ and T ₃ during the turning in FIG. 5F is a value corrected according to the vehicle speed SPD. Accordingly, the drive control amount of the actuator selected by the maximum value selection function 26 is as shown in FIG.

As described above, even if the estimated value of the relative speed between the sprung member and the unsprung member is erroneously set at the time of turning and the control amount of the damping force is incorrect, the control amount of the damping force is corrected. It is possible to prevent erroneous control of the damping force during the operation. by the way,
As for the damping force, the higher the vehicle speed, the harder the characteristic that emphasizes the running stability of the vehicle is required, and the lower the vehicle speed, the more the soft characteristic that emphasizes the riding comfort is required. As described above, the damping force characteristic is determined to some extent in accordance with the vehicle speed. Therefore, at the time of turning, the control according to the vehicle speed is performed to perform the control in a running state. Therefore, the control of the damping force according to the steering angle performed at the time of turning and the control of the damping force according to the skyhook theory can be performed without discomfort.

[0019]

As described above, the first aspect of the present invention provides
A suspension control device that estimates a sprung unsprung relative speed from a sprung acceleration and controls a damping force of a suspension mechanism according to a skyhook theory using the sprung speed obtained from the sprung acceleration and a steering angle. A steering angle detecting means for detecting, and a value obtained by correcting the damping force based on the skyhook theory at the time of turning from the detected steering angle.
There is a control amount correction means used for the skyhook control as the control amount.

For this reason, even if the estimated value of the sprung unsprung relative speed is incorrect and the control amount of the damping force is erroneous at the time of turning , the corrected value of the damping force is used as the control amount for the skyhook control.
To use, it is possible to prevent erroneous control of the damping force during turning. Further, the invention according to claim 2, in the suspension control apparatus according to claim 1, further comprising a vehicle speed detecting means for detecting a vehicle speed, the control quantity correcting means, to correct the damping force according to the vehicle speed value The sky hook as the control amount
Used for control .

For this reason, when turning, the damping force according to the vehicle speed is obtained.
The corrected value is used as a control amount in the skyhook control, and the control of the damping force according to the steering angle performed during turning and the control of the damping force according to the skyhook theory are performed without discomfort. Can be.

[Brief description of the drawings]

FIG. 1 is a principle diagram of the present invention.

FIG. 2 is a functional block configuration diagram of the device of the present invention.

FIG. 3 is a flowchart of a skyhook control routine.

FIG. 4 is a diagram showing a map.

FIG. 5 is a diagram for explaining the present invention.

[Explanation of symbols]

 10-13 Acceleration sensor 14 Speed angle sensor 15 Vehicle speed sensor 16 Brake switch 17 Rotation angle sensor 20 ECU 21 Skyhook control function 22 Steering control function 23 Vehicle speed control function 24 Anti-dive control function 25 Anti-square control function 26 Maximum value selection function 30 ~ 33 Actuator M1 Acceleration detecting means M2 Skyhook controlling means M3 Steering angle detecting means M4 Control amount correcting means M5 Suspension mechanism

Claims (2)

(57) [Claims] 1. The relative speed between a sprung member and a unsprung member is estimated from sprung acceleration, and the damping force of the suspension mechanism is calculated by the skyhook theory using the sprung speed obtained from the sprung acceleration and the sprung member. A suspension control device for controlling, a steering angle detection means for detecting a steering angle, and a value obtained by correcting a damping force based on the skyhook theory during a turn from the detected steering angle as a control amount.
A suspension control device comprising a control amount correcting means used for the shock control. 2. A suspension control system according to claim 1, further comprising a vehicle speed detecting means for detecting a vehicle speed, the control quantity correcting means, correct the damping force according to the vehicle speed
A suspension control device characterized in that the obtained value is used as a control amount for skyhook control .