JPH07315026A - Suspension control device for vehicle - Google Patents

Abstract

PURPOSE:To let riding comfort and control stability be compatible with each other when a vehicle is running over bad roads by providing the control device with a function for setting threshold values for positive and negative acceleration as a reference for setting damping force depending on a road surface condition, and with a function for setting a condition of damping force depending on the positive and negative acceleration in the case of bad roads. CONSTITUTION:The control section 36 of an electronic suspension controller 25 operates the magnitude of positive and negative acceleration detected by a positive and negative acceleration sensor 19, and their change rate, and a bad road detection counter 38 counts the number of times that the absolute values ¦G¦ of positive and negative acceleration exceed each specified limit. Furthermore, a road surface condition is judged with the aid of a memory section 37 and a bad road detection timer 39, and the threshold values of positive and negative acceleration as a reference for setting the damping force of a suspension mechanism for bad roads are so set as to be higher than those for good roads. Besides, in the case of bad roads, when actual acceleration is less than the threshold values of positive and negative acceleration which are set somewhat high, clamping force is set at a soft condition, when actual one is around the threshol values, damping force is set at a medium condition, and actual one exceeds the threshold values, damping force is set at a hard condition. Riding comfort and control stability can thereby be compatible with each other through fine control.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle suspension control device, and more particularly to a vehicle suspension control device suitable for improving riding comfort and steering stability when a vehicle is traveling on a bad road.

[0002]

2. Description of the Related Art Conventionally, the damping force of a suspension mechanism is divided into three states: "soft state", "medium state" and "hard state".
The in-vehicle suspension controller that controls switching in stages is a rough road sensitive control function that controls the damping force according to the road surface condition whether there is a protrusion or a step on the road surface of the vehicle, the front and rear left and right of the vehicle vibrate up and down at the same time It has various functions such as a pitching control function to suppress the pitching phenomenon and a bouncing control function to suppress the bouncing phenomenon in which the front and rear of the vehicle vibrate up and down in opposite directions.

In the rough road responsive control, when it is determined that the vehicle running road surface is a good road (during normal running), the damping force of the suspension mechanism is set to "soft state", and the vehicle running road surface is judged to be a bad road. By setting the damping force of the suspension mechanism to the "medium state", the trackability of the wheels on rough roads is enhanced to ensure steering stability, and the flapping of the wheels is suppressed to suppress deterioration of riding comfort. There is. In pitching control and bouncing control, the damping force of the suspension mechanism is set to "soft" during normal driving, and the damping force of the suspension mechanism is adjusted according to the degree of vibration generated in the vehicle when driving on a road surface with protrusions. Vibration is converged by setting to "medium state" or "hard state".

[0004]

However, in the above-mentioned conventional technique, the damping force of the suspension mechanism is fixed to the "medium state" when the traveling road surface state of the vehicle is determined to be a bad road. When the road surface condition is moderately rough, the riding comfort is good, but on the other hand, when the road surface condition is less rough, the insulation between the wheels and the road surface is deteriorated and the riding comfort is reduced. There has been a problem that the fluctuation of the vehicle cannot be effectively suppressed when the road surface is extremely rough and rough.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a suspension control device for a vehicle, in which the disadvantages of the above-mentioned conventional example are improved, and in particular, the riding comfort and the steering stability are compatible when the vehicle is traveling on a bad road. To that end.

[0006]

According to the present invention, a vertical acceleration sensor for detecting a vertical acceleration acting in the vertical direction of a vehicle equipped with a suspension mechanism, and a vertical acceleration detected by the vertical acceleration sensor fall outside a predetermined range. Control means for determining whether the road surface condition during running of the vehicle is a bad road or a good road based on the number of times the vehicle is running, and for setting the damping force of the suspension mechanism to a predetermined state according to whether the road surface condition is a bad road or a good road. In the vehicle suspension control device including the above, the control means sets the threshold value of the vertical acceleration, which is a reference when setting the damping force of the suspension mechanism, to a good road when the road surface condition is a bad road. The first function is to set a higher value than in the case, and when the road surface condition is a bad road, when the vertical acceleration is less than the threshold value set to the higher value, the damping force is set to the soft state and the vertical acceleration is set. The damping force is set to a medium state when is close to the high threshold value, and the damping force is set to a hard state when the vertical acceleration exceeds the high threshold value. It has the function of. This aims to achieve the above-mentioned object.

[0007]

According to the present invention, when the vehicle is traveling, when the road surface condition is judged to be a bad road, the control means sets the threshold value of the vertical acceleration, which is a reference for setting the damping force of the suspension mechanism, to a good road. Set higher than the case. Further, the control means, when the vertical acceleration is less than a high threshold value,
In other words, when there are few ups and downs or steps on the road surface while the vehicle is traveling, the damping force of the suspension mechanism is set to the soft state. That is, by setting the damping force to the soft state, the riding comfort of the vehicle traveling on the road surface with few undulations and steps is secured. On the other hand, the control means sets the damping force of the suspension mechanism to the medium state when the vertical acceleration is near the threshold value which is set to a high value, in other words, when the road surface while the vehicle is running has some undulations or steps. Set to. That is, by setting the damping force to a medium state, fluctuations in a vehicle traveling on a road surface having a certain amount of undulations, steps, etc. are suppressed. On the other hand, the control means sets the damping force of the suspension mechanism to the hard state when the vertical acceleration exceeds the threshold value set higher, in other words, when there are many ups and downs or steps on the road surface while the vehicle is traveling. . That is, by setting the damping force to the hard state, fluctuations in a vehicle traveling on a road surface with many ups and downs, steps, etc. are suppressed.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment to which the vehicle suspension control device of the present invention is applied will be described below with reference to the drawings.

First, the structure of the main part of a vehicle equipped with the vehicle suspension control device of this embodiment will be described with reference to FIG. 2. On the right front wheel side of the vehicle 1, an oil damper 3, a coil spring 4, and an actuator 5 are provided. Is equipped with a suspension mechanism 2 including an oil damper 7, a coil spring 8 and an actuator 9 on the left front wheel side, and an oil damper 11 and a coil spring 12 are installed on the right rear wheel side. , Actuator 1
3, a suspension mechanism 10 including 3 is provided, and a suspension mechanism 14 including an oil damper 15, a coil spring 16, and an actuator 17 is provided on the left rear wheel side.

Inside the vehicle 1, a steering sensor 18 for detecting the steering angle of the steering wheel, a vertical acceleration sensor 19 for detecting the vertical acceleration of the vehicle body when the vehicle 1 is running, and a vehicle speed are detected. Vehicle speed sensor 20
A throttle sensor 21 for detecting the degree of depression of the accelerator pedal by the vehicle driver, a brake switch 22 for detecting the operation state of the brake based on the depression operation of the brake pedal by the vehicle driver, and for extracting the engine rotation signal. An ignition coil 23 and an electronic suspension controller 25 for performing suspension control described later are provided.

Next, the configuration centered on the electronic suspension controller of the vehicle suspension control device of this embodiment will be described with reference to FIG. 1. The electronic suspension controller 25 is a control unit 3 for performing suspension control.
6, a storage unit 37 for storing a control program for suspension control and the like and having a built-in bad road detection flag / count flag, a bad road detection counter 38, and a bad road detection timer 39.

The control unit 36 of the electronic suspension controller 25 is connected to the battery 2 via fuses 26 and 27.
Ignition switch 3 via 8 and fuse 29
0, a brake switch 22, a stop lamp 31 that lights up when the brake is operated, an auto / sport switch 32, a DN switch 33, and an ignition coil 2.
3, the noise filter 34, and the sport / auto lamp 35 are connected to each other.

Further, the electronic suspension controller 2
The control unit 36 of 5 includes a vehicle speed sensor 20, a steering sensor 18, a vertical acceleration sensor 19, a throttle sensor 21, an engine controller (EPI controller) 40, and the oil dampers 3, 7, 11, and 15. Oil dampers 3, 7, so that the damping force is in a predetermined state (“hard state”, “soft state”, “medium state”)
Each actuator 5, 9, 13, which drives 11, 15
17 are connected to each other.

The control unit 36 of the electronic suspension controller 25 determines the steering operation state of the vehicle driver based on the output signal of the steering sensor 18, and detects the vertical acceleration acting on the vehicle body based on the output signal of the vertical acceleration sensor 19. The magnitude and the change rate of the vertical acceleration are calculated, the magnitude of the vehicle speed is calculated based on the output signal of the vehicle speed sensor 20, and the degree of depression of the accelerator pedal of the vehicle driver is determined based on the output signal of the throttle sensor 21. The operating state of the brake of the vehicle driver is determined based on the output signal of the brake switch 22.

The rough road detection counter 38 counts the number of times each time the absolute value of vertical acceleration | G | exceeds a predetermined range (see FIG. 3). Further, the rough road detection timer 39 has a function as a down timer, operates based on an instruction from the control unit 36, is subtracted at each timer interrupt of a constant cycle, and is clipped by "0". (See FIG. 3). In addition, the count flag has a comparison value of 0.1, which is a preset absolute value | G | of the vertical acceleration G.
It is set when it is outside the range of [G] and reset when it is within the range. The rough road detection flag is set when the count value of the rough road detection counter 38 is equal to or larger than the predetermined value N and is reset when the count value is smaller than the predetermined value N.

Next, the operation of this embodiment configured as described above will be described with reference to FIGS.

When the vehicle is running, the control unit 36 of the electronic suspension controller 25 reads the vertical acceleration G acting on the vehicle detected by the vertical acceleration sensor 19 (step S1 in FIG. 4), and the absolute value of the vertical acceleration G |
It is determined whether G | is within or outside the preset comparison value 0.1 [G] (step S2 in FIG. 4).

At time t0 in FIG. 3, since the vehicle is in good condition on the road surface, vertical vibration of the vehicle is small. Therefore, the absolute value | G | of the vertical acceleration G is within the comparison value 0.1 [G]. Therefore, the count flag is reset (see Fig. 4
Step S6), it is determined whether the count value of the rough road detection counter 38 is greater than or equal to the predetermined value N or less than the predetermined value N (step S7 in FIG. 4).

At time t0, since the road surface condition on which the vehicle is traveling is good and the count value of the bad road detection counter 38 is less than the predetermined value N, the value of the bad road detection timer 39 (down timer) is "0". It is determined (step S9 in FIG. 4). At time t0, since the value of the rough road detection timer 39 is not "0", it is determined whether the rough road detection flag is set (step S13 in FIG. 4).

At time t0, since the bad road detection flag is not set, that is, the road surface on which the vehicle is traveling is good, the threshold value of vertical acceleration in the pitching / bouncing control is set to the pavement threshold value ( Step S14 of FIG. 5). That is, it is determined whether the absolute value | G | of the vertical acceleration G is greater than or equal to the threshold value 0.2 [G] or less (step S15 in FIG. 5), and the absolute value | G | of the vertical acceleration G is equal to the threshold value 0. If less than 2 [G], each actuator 5, 9,
13 and 17 are drive-controlled to control the oil dampers 3, 7, 11,
The damping force of 15 is set to the "soft state" (step S16 in FIG. 5).

When the absolute value | G | of the vertical acceleration G is not less than the threshold value 0.2 [G], the absolute value | G of the vertical acceleration G
It is determined whether or not | is greater than or less than the threshold value 0.4 [G] (see FIG.
If the absolute value | G | of the vertical acceleration G is equal to or greater than the threshold value 0.4 [G], the actuators 5, 9, 13, 17 are drive-controlled to control the oil dampers 3, 3.
Damping force of 7, 11, 15 for a predetermined time (for example, 1 second)
After setting to "hard state", return to "soft state" (Fig. 5
Step S18).

When the absolute value | G | of the vertical acceleration G is more than the threshold value 0.2 [G] and less than 0.4 [G], the respective actuators 5, 9, 13, 17 are drive-controlled to control the respective oils. The damping force of the dampers 3, 7, 11, 15 is set for a predetermined time (for example, 1
After being set to the "medium state" (for a second), the state is returned to the "soft state" (step S19 in FIG. 5).

On the other hand, at time t1 in FIG. 3, the vertical road vibration of the vehicle is large due to the rough road surface of the vehicle, and therefore the absolute value | G | of the vertical acceleration G is within the comparison value 0.1 [G] range. Since it is outside, it is determined whether the count flag is "1" or "0" to count the number of times (step S of FIG. 4).
3). When the count flag is "0", that is, when the absolute value | G | of the vertical acceleration G is out of the range of the comparison value 0.1 [G], the rough road detection counter 38 is incremented by "1". (Step S4 in FIG. 4). The rough road detection counter 38 is cleared to zero in step S12 when the value of the rough road detection timer 39 is "0".

Next, the count flag is set (step S5 in FIG. 4), and the absolute value of the vertical acceleration G once detected.
Don't count G | again. Further, it is determined whether the count value of the rough road detection counter 38 is greater than or equal to the predetermined value N or less (step S7 in FIG. 4). At time t1, since the traveling road surface of the vehicle is rough and the count value of the bad road detection counter 38 is equal to or larger than the predetermined value N, the bad road detection flag is set (step S8 in FIG. 4).

Next, it is judged whether or not the value of the rough road detection timer 39 is "0" (step S9 in FIG. 4), and at time t1,
Since the value of the rough road detection timer 39 is not "0", it is determined whether the rough road detection flag is set (step S13 in FIG. 4).

At time t1, since the bad road detection flag is set, that is, the road surface on which the vehicle is traveling is a bad road, the vertical acceleration threshold in pitching / bouncing control is set to the bad road threshold. (Step S20 of FIG. 5). That is, it is determined whether the absolute value | G | of the vertical acceleration G is greater than or equal to the threshold value 0.3 [G] or less (step S21 in FIG. 5), and the absolute value | G | of the vertical acceleration G is equal to the threshold value 0. ．
If less than 3 [G], each actuator 5, 9, 1
Drive control of 3, 17 and each oil damper 3, 7, 11, 1
The damping force of 5 is set to the "soft state" (step S22 in FIG. 5).

When the absolute value | G | of the vertical acceleration G is equal to or more than the threshold value 0.3 [G], the absolute value | G of the vertical acceleration G
It is determined whether | is greater than or less than the threshold value 0.5 [G] (see FIG. 5).
Step S23), if the absolute value | G | of the vertical acceleration G is equal to or greater than the threshold value 0.5 [G], the actuators 5, 9, 13, 17 are drive-controlled to control the oil dampers 3, 3.
Damping force of 7, 11, 15 for a predetermined time (for example, 1 second)
After setting to "hard state", return to "soft state" (Fig. 5
Step S24).

When the absolute value | G | of the vertical acceleration G is greater than or equal to the threshold value 0.3 [G] and less than 0.5 [G], the respective actuators 5, 9, 13, 17 are drive-controlled to control the respective oils. The damping force of the dampers 3, 7, 11, 15 is set for a predetermined time (for example, 1
After being set to the "medium state" (for a second), the state is returned to the "soft state" (step S25 in FIG. 5).

Next, at the time t2, as in the case of the time t0, the vertical vibration of the vehicle is small because the road surface on which the vehicle is traveling is good. Therefore, the absolute value | G | of the vertical acceleration G is equal to the comparison value 0. Since it is within the range of 1 [G], step S
6, the processes of step S7 and step S9 are executed. At time t2, the value of the rough road detection timer 39 is “0”,
It is determined whether the count value of the rough road detection counter 38 is greater than or equal to the predetermined value N or less (step S10 in FIG. 4).

At time t2, since the road surface condition on which the vehicle is traveling is good and the count value of the bad road detection counter 38 is less than the predetermined value N, the bad road detection flag is cleared (step S11 in FIG. 4). Further, after clearing the rough road detection counter 38 to zero and setting the rough road detection timer 39 to a predetermined value Ts (step S12 in FIG. 4), it is determined whether or not the rough road detection flag is set (FIG. 4). Step S1
3).

At time t2, since the bad road detection flag is not set, that is, the road surface condition on which the vehicle is traveling is good, the processes of steps S14 to S19 of FIG. 5 are executed as at time t0. The above is a series of control flow by the electronic suspension controller 25 when the vehicle is traveling.

Here, when it is determined that the absolute value | G | of the vertical acceleration G is equal to or greater than the threshold value 0.5 [G] in the determination in steps S15 and S17 of FIG. 5 (when the road surface condition is a paved road). , Or when the absolute value | G | of the vertical acceleration G is greater than or equal to the threshold value 0.5 [G] in the determinations of steps S21 and S23 (when the road surface is a paved road), both are damped. Power to "hard state" 1
After holding for a second, control to return to the "soft state" is performed,
This assumes that there is a hole or the like in the middle of a flat paved road, for example.

In this case, in the above-mentioned pitching / bouncing control, the threshold value of vertical acceleration when the running road surface state of the vehicle is a bad road and the threshold value of vertical acceleration when the road surface is a good road are set separately. The reason is that if the vertical acceleration threshold is set to the optimum threshold for bad roads, the threshold for vertical acceleration is too high on good roads to prevent vertical fluctuations of the vehicle. This is because when the threshold value of is set to an optimum threshold value for a good road, the damping force of the suspension mechanism is biased to the “medium state” or the “hard state” on a bad road to prevent a problem that the riding comfort is deteriorated.

As described above, according to this embodiment, the damping force of the suspension mechanism is set to the "soft state" when the degree of road surface roughness is small, so that riding comfort can be ensured. When the road surface is in a moderate degree of roughness, the suspension mechanism damping force is set to "medium state", and when the road surface is rough, the suspension mechanism damping force is set to "hard state". Since the setting is made, the fluctuation of the vehicle can be suppressed.

As described above, as in the conventional case where the damping force of the suspension mechanism is fixed to the "medium state" when the running road surface state of the vehicle is determined to be a bad road, the road surface state is in a rough condition. The ride comfort is sometimes improved, but the ride comfort is reduced when the road surface is less rough, and the fluctuation of the vehicle cannot be effectively suppressed when the road is extremely rough and the road is rough. In addition, it is possible to perform fine grained suspension control on rough roads.

Here, in the present embodiment, the damping force of the oil damper of the suspension mechanism is simultaneously switched to the left and right front wheels and the left and right rear wheels. It is possible to obtain the same effect as above by independently switching. Also,
In the present embodiment, the damping force is switched to three stages, but the same effect as above can be obtained even if the damping force is switched to multiple stages or the spring constant is switched.

[0037]

As described above, according to the vehicle suspension control device of the present invention, the threshold value of the vertical acceleration, which becomes the reference when setting the damping force of the suspension mechanism, is set to the road surface condition of the bad road. In this case, since the threshold is set higher than that on a good road, the threshold is too high on a good road such as when the vertical acceleration threshold is adjusted to a bad road, and vehicle fluctuation cannot be suppressed. It is possible to solve the problem that the riding comfort deteriorates on a bad road such as when the acceleration threshold value is adjusted to a good road. Further, when the vertical acceleration is less than a high threshold value, that is, on a road surface with relatively few rough surfaces (undulations, steps, etc.), the damping force is set to a soft state, so riding comfort can be secured. When the vertical acceleration is near the high threshold value, that is, on a road surface where the roughness is moderate (undulations, steps, etc.), the damping force is set to a medium state and the vertical acceleration is set to a high threshold value. When the vehicle exceeds the limit, that is, on a road surface with a lot of roughening (undulations, steps, etc.), the damping force is set to a hard state, so it is possible to suppress the fluctuation of the vehicle due to the roughening of the road surface. The effect is that fine suspension control can be performed.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a control system centered on an electronic suspension controller according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a configuration of a main part of a vehicle equipped with an electronic suspension controller according to the present embodiment.

FIG. 3 is a time chart for explaining suspension control in this embodiment.

FIG. 4 is a flow chart of a first half portion of suspension control in this embodiment.

FIG. 5 is a flowchart of the latter half of suspension control in this embodiment.

[Explanation of symbols]

 1 Vehicle 19 Vertical acceleration sensor 36 Control unit as control means

Claims (1)

[Claims] 1. A vertical acceleration sensor for detecting a vertical acceleration acting in a vertical direction of a vehicle equipped with a suspension mechanism, and the traveling of the vehicle based on the number of times the vertical acceleration detected by the vertical acceleration sensor falls outside a predetermined range. Suspension control for a vehicle, comprising: a control unit that determines whether the inside road surface condition is a bad road or a good road, and sets the damping force of the suspension mechanism to a predetermined state according to whether the road surface condition is a bad road or a good road. In the device, the control means sets the threshold value of the vertical acceleration, which is a reference when setting the damping force of the suspension mechanism, to be higher in a bad road condition than in a good road condition. If the vertical acceleration is less than the threshold value set to the high value when the road surface condition is a bad road, the damping force is set to the soft state and the vertical acceleration is set to the high value. Sets the damping force to the medium state when in the vicinity have value,
A vehicle suspension control device having a second function of setting the damping force to a hard state when the vertical acceleration exceeds the higher threshold value.