JPH0672129A - Suspension controller for vehicle - Google Patents

Abstract

PURPOSE:To obtain the control over a wide range of a car speed for a delay time by making the surface detecting position of a road surface detecting sensor variable, by adjusting either the delay time or sensor moving quantity for an actuator on the front wheel side, and by adjusting the delay time on the rear wheel side, so that the damping force variable signal can be outputted separately. CONSTITUTION:A front wheel 2 and a rear wheel 3 are provided with shock absorbers 20, 20' having a damping force variable device and suspensions 5, 5' equipped with motors 7, 7' which can control/vary the damping force. In addition, a road surface sensor 10, which can detect the irregularity of the road surface, is installed in the forward, lower part of a car body 1 in such a manner that the sensor 10 can be moved forward from the vicinity of the front wheel 2 so as to vary its road surface detecting position. The signal from the road surface sensor 10 and a car speed sensor 13 is processed by a control unit 14. With regard to the motor 7 of the front wheel suspension 5, the delay time or sensor moving quantity is adjusted in correspondence to the car speed, while, with regard to the motor 7' of the rear wheel suspension 5', the actuation is delayed by the delay time for the entire range of the car speed. Thus, the damping force variable signal corresponding to the irregularity of the road surface can be outputted separately.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for variably controlling suspension characteristics in an active suspension which is provided on each wheel of a vehicle and whose damping force is variable, according to the unevenness of the road surface.

[0002]

2. Description of the Related Art Generally, a suspension is provided between a vehicle body and an axle of each wheel of a vehicle and has a spring and a shock absorber. The spring absorbs a shock from the road surface, and a continuous vibration of its rebound is absorbed by the shock absorber. Is dampened by, and shocks are alleviated. For this reason, if the damping force of the shock absorber is large, it is possible to quickly damp the vibration and reduce changes in the vehicle attitude to improve maneuverability. Conversely, if the damping force is small, the vibration will continue and ride comfort will be improved. Etc. can be improved. Therefore, in recent years, a damping force varying device has been added to the shock absorber to enable active variable control of suspension characteristics. Then, the damping force of the characteristics of this suspension can be variably controlled softly or hardly depending on the road surface condition on good roads and bad roads, running conditions such as braking, starting, turning, etc. to achieve both stability and ride comfort. Is proposed.

Here, in the posture stability control for changing the suspension characteristic with respect to the unevenness of the road surface, a road surface sensor such as an ultrasonic system for detecting the unevenness of the road surface is provided at the front part of the vehicle body. In this case, the road surface sensor is desired to be mounted so as to detect the road surface near the front wheels in order to reduce the detection error due to the pitching of the vehicle. Further, the control system is configured to input a signal from the road surface sensor, process the signal in the control system, and operate the actuator of the damping force varying device of the suspension.

Therefore, in this control system, there is a time delay in each of the sensor system, the control system and the actuator system.
There is an overall delay time that is the sum of these. Therefore, considering the sensor mounting position near the front wheels and the delay time of the entire control system, there is no time margin for using the road surface information detected by the road surface sensor for suspension characteristic change control at a certain vehicle speed. When it becomes above, it becomes out of control. For this reason, it is required to be able to change and control the suspension characteristics in a wide range of vehicle speed with respect to the sensor mounting position and the delay time of the entire control system. Further, if the suspension of four wheels is controlled at the same time, it cannot be applied when unevenness of the road surface occurs in a short cycle. Therefore, it is necessary to individually control the suspensions of the front wheels and the rear wheels in accordance with the timing when the front wheels and the rear wheels reach the uneven portion.

Conventionally, as to the suspension characteristic changing control for the unevenness of the road surface, for example, Japanese Patent Application Laid-Open No. 3-182 is known.
There is a prior art of Japanese Patent No. 825. Here, it is shown that a road surface unevenness sensor is provided in the lower part of the front end of the vehicle body and the suspension characteristics are changed based on the sensor output.

[0006]

By the way, in the above-mentioned prior art, since the road surface unevenness sensor is fixedly provided on the vehicle body, the road surface which is always separated by a certain distance in front of the front wheels is detected. At high speeds, it may not be possible to change and control the suspension characteristics due to the delay time of the entire control system.

The present invention has been made in view of this point, and in the suspension characteristic changing control by the road surface sensor, it is possible to control in a wide range of vehicle speed with respect to the sensor mounting position and the delay time of the entire control system, and The purpose is to control the front and rear wheel suspensions appropriately.

[0008]

In order to achieve the above object, the present invention provides a vehicle in which a wheel is provided with a spring, a shock absorber having a damping force varying device, and a suspension provided with an actuator for variably controlling the damping force. , A road surface sensor that detects the unevenness of the road surface at the lower front of the vehicle body is provided so that the road surface detection position can be changed by moving from near the front wheel to the front, and the road surface sensor and the signal of the running state are processed by the control unit, For the actuator of the front wheel suspension, adjust the delay time or the sensor movement amount and output the damping force variable signal according to the road surface unevenness,
With respect to the actuator of the rear wheel suspension, the delay time is adjusted, and damping force variable signals corresponding to road surface irregularities are separately output to operate.

[0009]

According to the above structure, for the actuator of the front wheel suspension, the delay time is adjusted by the control unit or the sensor movement amount is adjusted to move the road surface sensors to the front of the vehicle body in order, and the road surface is moved earlier. A variable damping force signal is detected and output according to the unevenness of the road surface. This makes it possible to control the delay time of the entire control system in a wide vehicle speed range. Further, for the actuators of the rear wheel suspension, the control unit delays by a delay time considering the wheel base and the like, and a damping force variable signal corresponding to the road surface unevenness is output separately. Therefore, even if the front wheel moves to the next uneven part, when the rear wheel reaches the uneven part, the suspension is
As in the case of the front wheels, damping action is performed so as to appropriately change the suspension characteristics, and the vehicle attitude is reliably and stably controlled.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. An outline of a vehicle suspension control system will be described with reference to FIG. Reference numeral 1 denotes a vehicle body, and a suspension 5, between the axle 4 of the front wheels 2 and the rear wheels 3 and the vehicle body 1.
5'is installed respectively. Front wheel suspension 5
Is configured such that a spring 6 and a damping force variable shock absorber 20 are provided in parallel between the vehicle body 1 and the axle 4, and an electric motor 7 is provided above the shock absorber 20 as an actuator for variably controlling the damping force. To be done. The rear wheel suspension 5'has the same configuration, and the same parts are denoted by the same reference numerals with a dash and the description thereof is omitted.

In front of the front wheel 2 of the vehicle body 1, a road surface sensor 10 for detecting the unevenness of the road surface is mounted on a moving device 11, and the motor 12 as an actuator linearly moves the road surface sensor 10 forward. It is possible to change the road surface detection position. Further, it has a vehicle speed sensor 13 for detecting a traveling state. The signals of the road surface sensor 10 and the vehicle speed sensor 13 are input to the control unit 14, and the output signals of the control unit 14 actuate the motors 7 and 7'of the front and rear wheel suspensions 5 and 5'and the motor 12 of the moving device 11. Is composed of.

The control unit 14 outputs a damping force variable signal to the front and rear wheel suspensions 5 and 5'to the front and rear wheel suspensions 5 and 5'at a proper timing in accordance with the relationship between the sensor mounting position and the delay time of the entire control system. The control law will be described below. First, the control law for the front wheel suspension 5 will be described.
The vehicle speed is V, the delay time of the entire control system is Δt, the shortest front-back distance between the sensor and the tire center is Lo, and the sensor movement amount is ΔL.
When the delay time adjusted when the road surface unevenness information is used for control is ΔTf, the following equation holds. (Lo + ΔL) / V = Δt + ΔTf Here, at low speed, ΔTf when the sensor is fixed at ΔL = 0.
By controlling, the damping force variable signal can be output at the timing that matches the delay time Δt. Further, at medium and high speeds, by controlling the sensor movement amount ΔL with ΔTf = 0, it is possible to absorb the delay time Δt and output a damping force variable signal.

Therefore, the vehicle speed V and Lo / Δt are compared. Then, at the low speed of V ≦ Lo / Δt, ΔL = 0 is set, and the delay time ΔTf is controlled by ΔTf = Lo / V−Δt. Also, when V> Lo / Δt at medium and high speeds,
With ΔTf = 0, the sensor movement amount ΔL is controlled by ΔL = V · Δt−Lo.

Next, the control law for the rear wheel suspension 5'will be described. When the vehicle speed is V, the delay time of the entire control system is Δt, the wheel base is Lwb, and the delay time adjusted when the road surface unevenness information is used for control is ΔTr, the following equation is established. (ΔTr + Δt) V = Lwb Therefore, it is possible to predict the time for the rear wheel 3 to reach the uneven portion subsequently to the front wheel 2 with the delay time ΔTr including the wheel base Lwb in this case. By outputting a variable damping force signal,
It is possible to properly operate the rear wheel suspension 5'with a predetermined uneven portion regardless of the state of the front wheel 2. Therefore, the delay time ΔTr is controlled by ΔTf = Lwb / V−Δt in the entire vehicle speed range.

Referring to FIG. 2, a concrete configuration of the damping force type shock absorber 20 will be described. In the shock absorber 20, a rod 22 on the vehicle body 1 side has a piston 23 and is movably inserted into a cylinder 21 on the axle 4 side. The piston 23 divides the rod 22 into an upper chamber 24 and a lower chamber 25 and fills with oil O. To be done. The piston 23 is provided with a main passage 26 and a main valve 26a on the extension side and a main passage 27 and a main valve 27a on the contraction side, respectively. When the rod is extended and the main valve 26a is opened, the oil O flows from the upper chamber 24 to the lower chamber 25 through the main passage 26. Conversely, when the rod is compressed and the main valve 27a is contracted, the other main valve 27a is opened. Open lower chamber 25
From the oil O flows into the upper chamber 24 via the main passage 27. Here, the orifice diameters of the main passages 26 and 27 are set to be small, so that the same hard damping force is generated on the extension side and the contraction side.

A damping force varying device 30 is provided inside the rod 22. This damping force varying device 30
A communication hole 31 is provided at the center of the rod 22 so that the lower end thereof communicates with the lower chamber 25, and the communication hole 31 extends toward the extension side sub passage 3.
2 and the sub-valve 32a, the contraction-side sub-passage 33 and the sub-valve 33a, and the sub-passage 34 that serves both functions, and communicate with the upper chamber 24. Further, a shutter 35 from the motor 7 is rotatably inserted into the communication hole 31 via a connecting rod 36, and three types of holes 38, 3 are formed on the circumference of the shutter 35.
9, 40 are provided by being displaced by a predetermined rotation angle.

Therefore, when the shutter 35 is rotated by a predetermined angle by the motor 7 so that only the hole 38 communicates with the sub passage 32, the sub valve 32a is closed when the rod is contracted by being lowered. When the rod rises and extends, the sub valve 3
2a is also opened, and the oil O in the upper chamber 24 also flows into the sub passage 32 to increase the orifice diameter, which results in the first mode damping force characteristic of FIG. 3 in which the extension side is soft and the contraction side is hard. Then, when the other hole 39 is communicated with the sub passage 33 by the motor 7, in this case, the sub valve 33a is also opened to increase the orifice diameter only when the rod is contracted by the rod lowering contrary to the above, and therefore the expansion side is hard and contracts. The side has soft damping characteristics of the second mode in FIG.
Further, when the other hole 40 communicates with the sub-passage 34 by the motor 7, in this case, the oil O constantly flows in the sub-passage 34 to increase the orifice diameter, so that the third side of FIG. It has a mode damping characteristic. In this way, the motor 7 can obtain damping characteristics of three types of modes.

Next, the operation of this embodiment will be described with reference to the flowchart of FIG. First, when the vehicle is traveling, the vehicle speed V is read in step S1, and the vehicle speed V and Lo /
The running state is checked by comparing Δt. Here, as practical numerical values, for example, Lo = 0.5 m, Δt = 0.03.
In seconds, Lo / Δt = 60 Km / h. Therefore, at a low speed of 60 km / h or less, the process proceeds to step S3, ΔL = 0 is set, the sensor position is fixed to the shortest distance, and the delay time ΔTf for the front wheel suspension 5 is adjusted according to the vehicle speed V based on the above equation. Therefore, the delay time ΔTf in this case is as shown by the solid line in FIG. 5A with respect to the vehicle speed V, and is adjusted in a decreasing function up to a predetermined vehicle speed Lo / Δt.

The delay time ΔTr for the rear wheel suspension 5'is also adjusted according to the vehicle speed V based on the above equation. Therefore, the delay time ΔTr in this case is adjusted with respect to the vehicle speed V by a gradual decreasing function as shown by the broken line in FIG. Therefore, the delay time ΔTr is always delayed with respect to the delay time ΔTf and set to be large. Thereafter, in step S4, the road surface unevenness information by the road surface sensor 10 is read, and in step S5, a damping force variable signal suitable for the unevenness information is output to the motor 7 of the shock absorber 20 of the front wheel suspension 5 at the timing when the delay time ΔTf has elapsed. . In addition, the same damping force variable signal is delayed by the delay time ΔTr and separately output to the motor 7 ′ of the shock absorber 20 ′ of the rear wheel suspension 5 ′.

Then, as shown in FIG. 6, when the road surface sensor 10 at the front part of the vehicle body 1 detects the convex portion A, the damping force variable signal of the second mode of FIG. 3 is output. That is, first, when the front wheel 2 reaches the convex portion A, the damping force variable signal is output to the motor 7 of the front wheel suspension 5 without causing a time delay, so that the damping force varying device 30 operates in the second mode. It becomes possible to operate with the characteristics of. Therefore, when the front wheel 2 actually travels on the convex portion A and moves upward, the damping force varying device 30 has a soft damping action on the contraction side and a hard damping action on the extension side. Then, when the rear wheel 3 reaches the convex portion A with a delay, the same signal is output to the motor 7'of the rear wheel suspension 5 ', and it becomes possible to operate with the same characteristics. As a result, even if the front wheel 2 moves to the next uneven portion, the rear wheel suspension 5'attenuates the same, regardless of this, so that the upward movement of the vehicle body 1 is reliably suppressed.

On the other hand, when the road surface sensor 10 detects the concave portion B, the damping force variable signal of the first mode in FIG. 3 is sent to the motor 7 first at the timing of the delay time ΔTf, and then at the delayed timing ΔTr of the delay time. Motor 7 '
Output to. Therefore, when the front wheel 2 and the rear wheel 3 travel in the recess B in order and move downward, the front and rear wheel suspensions 5,
In the damping force varying device 30 of 5 ', the extension side is softly damped and the contraction side is hardly damped due to the characteristics of the first mode, and the downward movement of the vehicle body 1 is reliably suppressed. In this way, the vehicle body 1 of the vehicle is controlled so as to maintain a posture in which there is little vertical movement with respect to the uneven portions A and B of the road surface.

Next, when the vehicle speed is above 60 km / h, the process proceeds from step S2 to step S6 in the flow chart of FIG.
The delay time ΔTf is fixed with f = 0. Then, the sensor movement amount ΔL is adjusted according to the vehicle speed V based on the above equation. Therefore, the sensor movement amount ΔL in this case is as shown in FIG. 5B with respect to the vehicle speed V, and the predetermined vehicle speed Lo / Δt is obtained.
After that, it is adjusted in an increasing function.

Therefore, in this case, as the vehicle speed V increases, the road surface sensor 10 is sequentially moved forward from the position of the shortest front-rear distance close to the front wheel 2 by the moving device 11 by an amount corresponding to the delay time Δt of the entire control system. The road surface is detected early after moving. In this way, the road surface sensor 10 obtains the road surface unevenness information early, so that the delay of the entire control system is absorbed. Here, the specific numerical values described above, Lo = 0.5 m, Δt = 0.03.
Seconds and the maximum sensor movement amount ΔL are, for example, ΔL = 0.5
When m, the maximum controllable vehicle speed is 120 km / h, which is sufficiently practical. On the other hand, for the rear wheel suspension 5 ′, the delay time ΔTr is adjusted and determined in this case as well, as described above.

Then, step S in the flowchart of FIG.
4, the damping force variable signal suitable for road surface unevenness information is immediately output to the front wheel suspension 5 in the same manner as described above. For the rear wheel suspension 5 ',
The damping force variable signal is output after being delayed by the delay time ΔTr. Therefore, the front wheel 2 and the rear wheel 3 are sequentially arranged on the road surface uneven portion A,
When you reach B and drive,
5'becomes operable in the same manner, and damping is performed so as to change the suspension characteristics, so that the vehicle attitude is stably controlled.

When the road surface sensor 10 detects a flat road surface, the damping force varying device 30 is controlled so that the extension side and the contraction side are slightly soft according to the characteristics of the third mode of FIG.
This improves ride comfort.

The embodiment of the present invention has been described above, but the present invention is not limited to this.

[0027]

As described above, according to the present invention,
In the vehicle attitude control that changes the suspension characteristics according to the unevenness of the road surface by providing the road surface sensor on the vehicle body, the road surface sensor is configured to always detect the road surface close to the wheels. The road surface can be accurately detected in a state in which the influence of is small and the control accuracy is improved. In the front wheel suspension, it is controlled to adjust the delay time or the sensor movement amount and input the damping force variable signal with respect to the sensor mounting position and the delay time of the entire control system. The characteristics of the suspension can be changed appropriately.

Since the rear wheel suspension is controlled so as to be delayed by a delay time considering the wheel base and the like in the entire vehicle speed range and the damping force variable signal is input separately,
It is possible to reliably change the suspension characteristic next to the front wheel with the same uneven portion. Further, the separation control of the rear wheel suspension makes it possible to adapt to the case where irregularities occur in a short cycle, which is highly practical.

[Brief description of drawings]

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

FIG. 2 is a cross-sectional view showing a variable damping force type shock absorber.

FIG. 3 is a diagram showing a damping force characteristic of a suspension.

FIG. 4 is a flowchart showing suspension characteristic change control according to the unevenness of the road surface.

FIG. 5 is a diagram showing an adjustment state of a delay time and a sensor movement amount.

FIG. 6 is a schematic view showing a concavo-convex state of a road surface.

[Explanation of symbols]

 1 vehicle body 2 front wheel 3 rear wheel 5,5 'suspension 6,6' spring 7,7 'motor 10 road surface sensor 11 moving device 13 vehicle speed sensor 14 control unit 20, 20' shock absorber 30 damping force varying device

Claims (2)

[Claims] 1. A vehicle in which a wheel is provided with a spring, a shock absorber having a damping force varying device, and a suspension equipped with an actuator for variably controlling the damping force, and a road surface sensor for detecting unevenness of the road surface at a lower front portion of a vehicle body, It is provided so that the road surface detection position can be changed by moving from near the front wheels to the front, and the signal of this road surface sensor and running condition is processed by the control unit, and the delay time or sensor movement amount is set for the actuator of the front wheel suspension. Adjust and output a damping force variable signal according to the road surface unevenness,
A suspension control device for a vehicle, characterized in that a delay time is adjusted for an actuator of a rear wheel suspension, and a damping force variable signal corresponding to road surface irregularities is separately output to operate. 2. The control unit controls the vehicle speed, the shortest front-rear distance between the sensor and the tire center, and the delay time of the entire control system.
Adjust the delay time or the sensor movement amount and output the damping force variable signal to the actuator of the front wheel suspension, and further adjust the delay time according to the vehicle speed, the wheel base, and the delay time of the entire control system to output the damping force variable signal. 2. The vehicle suspension control device according to claim 1, wherein the suspension control device controls the actuator of the rear wheel suspension so as to output the actuator.