JP2501170B2 - Suspension control device for vehicle - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle for improving steering stability during turning braking by controlling characteristics of a damping force variable shock absorber, a spring constant variable spring device, a roll stiffness variable stabilizer and the like. Suspension controller for vehicle.

[0002]

2. Description of the Related Art A conventional vehicle suspension control device is disclosed in, for example, Japanese Patent Laid-Open No. 56-42739. In the above-mentioned conventional vehicle suspension control device, the vehicle running state such as the steering angle of the steering wheel, the vehicle speed, and the presence or absence of the brake pedal operation is detected, and the damping force of the shock absorber is increased or decreased in accordance with these detection signals. The rolling control and the pitching of the vehicle are suppressed by the switching control.

However, in the above-mentioned conventional vehicle suspension control device, the damping force is increased in order to suppress the posture change of the vehicle body during braking or turning. The damping force is controlled to be high even during turning braking in which steering and braking are simultaneously performed at or above a predetermined value, and the load sharing on the turning outer wheel side sharply increases and the load sharing on the turning inner wheel side sharply decreases. As a result, the load sharing difference between the inner and outer wheels becomes large, and the total cornering power of the inner and outer wheels decreases, so that the ground contact property is deteriorated, and skidding is likely to occur, resulting in a problem that the steering stability is deteriorated. This tendency indicates that the damping force of the shock absorber has three levels (high, medium,
In the case of switching to low) and the switching to more stages, the damping force value in the high stage is set to a value larger than that in the high stage in the case of two stages, so that it becomes particularly remarkable.

Therefore, an object of the present invention is to prevent the cornering power from decreasing even during turning braking in which steering and braking are simultaneously performed for a predetermined amount or more, and to improve steering stability during braking during cornering. There is.

In order to solve the above problems, according to the present invention, as shown in the basic configuration diagram of FIG. 1, a steering state detecting means for detecting a steering state of a vehicle and a braking state of the vehicle. Driving state detecting means for detecting a vehicle traveling state including a braking state detecting means for detecting the vehicle running state, and control of the suspension device for suppressing a change in vehicle body posture based on a detection signal of the traveling state detecting means. It is determined whether or not the control means for controlling the characteristics to be switched in at least three stages of low, medium, and high, and the detection signals of the steering state detecting means and the braking state detecting means are in the steering and braking states above a predetermined level. The judging means and the judgment result of the judging means indicate that the steering or braking state is equal to or more than a predetermined value.
And a blocking means for blocking the switching to the high stage by the control means at the time of resetting .

In the present invention, the running condition other than during turning braking is
In the state, the control unit detects the detection signal of the traveling state detection unit.
The control characteristics of the suspension system are switched based on
This suppresses changes in the posture of the vehicle body , but during turning braking in which steering and braking are performed for a predetermined amount or more, the control means of the suspension device is set at a high level by the blocking means. the cut inhibitory that replace abolish Runode, allowing the attitude of the vehicle body changes, by reducing the decrease of the load quantity the amount of increase and the turning inner wheel side of the load distribution of the turning outer wheel side, the shared load difference between the inside and outside wheels It is possible to reduce the total cornering power and improve steering stability.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 is a schematic configuration diagram showing an embodiment in which the present invention is applied to a damping force variable shock absorber capable of controlling a damping constant which is one of the control characteristics of a suspension device. FIG. 3 shows the present invention. Sectional drawing which shows an example of a damping force variable shock absorber which can be applied, FIG.4 (a) and (b) is sectional drawing on the II line and II-II line of FIG. 3, respectively.
FIG. 5 is a block diagram showing an example of a control device applicable to the present invention, and FIG. 6 is a flow chart showing an example of a processing procedure of the control device.

First, the structure will be described. In FIG. 2, 1a and 1b are front wheels, 1c and 1d are rear wheels, and 2a to 2a.
d is a damping force variable shock absorber as a suspension device, and these damping force variable shock absorbers 2a to 2d are mounted between the wheels 1a to 1d and the vehicle body 3, and the damping force thereof is switched to control the vehicle body. Three
The vibration component according to the posture change of the vehicle and the road surface state transmitted to the vehicle body 3 is suppressed.

Variable damping force shock absorbers 2a to 2d
In one example, as shown in FIG. 3, a piston 9 is attached to the tip of the inner cylinder 8 of the piston rod 5, and a central opening 10 is formed to extend through the piston 9 in the axial direction. A variable diaphragm 11 is formed at the upper end of the central opening 10. As shown in FIGS. 4 (a) and 4 (b), the variable diaphragm 11 has three kinds of through holes 12h, 12m, 12s having different opening areas at the upper position and formed in the same horizontal plane at equal angular intervals. At the same time, two kinds of through holes 13h and 13m having different opening areas are also provided at the lower position.
Formed in the same horizontal plane facing 2m and center opening 1
4 and a shield cylinder 18 having one opening 16 and 17 at a position opposed to the through holes 12h to 12s and 13h and 13m, respectively. . Thus, the shield cylinder 18 is connected to the rotary shaft of the electric motor 19 installed in the piston rod 5 to be rotationally driven, and is urged downward by the return spring 20 between the openings 16 and 17. The check valve 21 is provided.

Further, the electric motor 19 is rotationally driven by a drive current from output circuits 39F and 39R of the control device 37, which will be described later, and its rotational position is detected by a rotational position detector 22 such as a potentiometer attached to the rotary shaft. Then, the detection signal is supplied to the control device 37 as a feedback signal. Further, the piston 9 is provided with an extension-side orifice 23 and a contraction-side orifice 24, which are relatively small pores that allow the working fluid C in the fluid chambers A and B defined thereby to pass therethrough.

Therefore, in the state where the shield cylinder 18 is in the first rotation position Rs shown in FIGS. 4A and 4B, the openings 16 and 17 of the shield cylinder are respectively the maximum opening area of the cylinder 15. Since it faces through holes 12h and 13h having
When the piston rod 5 moves in the contraction direction,
The working fluid C from the fluid chamber B flows into the fluid chamber A through the central opening 10 through the through holes 12h and 13h, and also through the contraction-side orifice 24 into the fluid chamber A, so that the through holes 12h and 13h. Since the opening area of is large, the fluid resistance is relatively small. On the other hand, when the piston rod 5 moves to the extension side, the check valve 21 blocks the inflow of the working fluid from the through hole 12h.
The working fluid C flows into the fluid chamber B from the fluid chamber A through the through hole 13h and the extension side orifice 23, and eventually, the damping force of the shock absorber is changed as a whole while causing a difference in the damping force in the contraction direction and the extension direction of the piston rod 5. Is controlled to the minimum damping force S.

When the electric motor 19 is driven from this state to rotate the shielding cylinder 18 to the second rotation position R _M , in this state, the openings 16 and 17 of the shielding cylinder 18 are through holes. Since they are opposed to 12 m and 13 m, and their opening areas are medium, the fluid resistance is increased and the damping force of the shock absorber is increased to the intermediate damping force M as compared with the above case.

Furthermore, when the electric motor 19 is driven from this state to rotate the shielding cylinder 18 to the third rotation position R _H , only the opening 16 of the shielding cylinder 18 is the smallest opening in this state. Will face the through hole 12s having an area,
The fluid resistance on the contraction side is maximized, and the working fluid C from the through hole 12s is blocked by the check valve 21 on the extension side. Therefore, the working fluid from the fluid chamber A passes through only the extension side orifice 23. Since the fluid flows into the fluid chamber B, the fluid resistance on the contraction side and the extension side is maximized, and the damping force of the shock absorber is increased to the maximum damping force H.

Further, as shown in FIG. 2, the vehicle has a vehicle speed detector 26 for outputting a vehicle speed detection signal DV corresponding to the output side rotation speed of a transmission (not shown) connected to the engine,
Steering angle detector 2 that detects the turning position of the steering wheel 27 and outputs a steering angle detection signal Dθ corresponding to the steering angle.
8, an acceleration / deceleration detector 30 that outputs an acceleration / deceleration detection signal DA corresponding to the depression state of the accelerator pedal 32, and a braking that detects the depression state of the brake pedal 31 and outputs a braking detection signal DB corresponding to the braking state. The detector 32, the road surface state detector 33 configured by an ultrasonic distance measuring device that outputs a road surface state detection signal DR according to the road surface state, and the front wheel 1 of the vehicle body 3.
Vehicle height detectors 34F and 34R constructed by an ultrasonic distance measuring device attached to the lower surface of the front portion of a and the rear wheel 1c
An automatic / manual selection switch 35 and a damping force selection switch 36 for manual operation are provided for selecting whether to perform suspension control automatically or manually. The vehicle speed detector 26, the steering angle detector 28,
The acceleration / deceleration detector 30 and the braking detector 32 constitute a traveling state detecting means.

Then, each detector 26, 28, 30, 3
The detection signals of 2, 33, 34F and 34R and the switch signals of the auto / manual selection switch 35 and the damping force selection switch 36 are supplied to the control device 37. Controller 37
Is a microcomputer 38, as shown in FIG.
It is composed of output circuits 39F and 39R connected to the output side thereof.

The microcomputer 38 has at least an interface circuit 38a, an arithmetic processing unit 38b, and a storage unit 38c, and executes arithmetic processing according to a processing program shown in FIG. That is, first, in step S1, it is determined whether or not the system is operating normally. If the system is operating normally, each command value storage area, which will be described later, is cleared, and the process proceeds to step S2 to execute automatic
It is determined whether the manual selection switch 35 is switched to the automatic side or the manual side. At this time, if the mode is switched to the auto side, the process proceeds to step S3.

In this step S3, the damping force variable shock absorbers 2a, 2b and 2c on the front wheel side and the rear wheel side,
A control command value CFs for controlling both 2d to the minimum damping force S,
After storing CRs in the initial setting storage area of the storage device 38c, the process proceeds to step S4. In this step S4,
The detection signal DV of the vehicle speed detector 26 is read, the vehicle speed V is calculated based on the detection signal DV, and it is determined whether the vehicle speed V is equal to or higher than a predetermined set vehicle speed Vs. At this time, the vehicle is set to Vs
If the vehicle is traveling at a low speed, the step S5
Move to

In step S5, the acceleration / deceleration detector 30
It is determined whether the vehicle is decelerating or accelerating except for the braking state by depressing the brake pedal based on the detection signal DA of step S6. If the vehicle is traveling at a constant speed without decelerating or accelerating, the process proceeds to step S6. Transition. This step S6
Then, the detection signals of the vehicle height detectors 34F and 34R are read, and it is determined whether or not the vehicle is in the bottoming state in which the vehicle passes through the temporary unevenness and the vertical vibration is generated in the vehicle body 3. The process proceeds to S7.

In step S7, the road surface condition detector 3
The detection signal DR of No. 3 is read, and it is determined whether or not the road surface on which the vehicle is traveling is a small road as a predetermined traveling condition. In this case, the unsprung resonance frequency component having a relatively high frequency (10 to 12 Hz) and the unsprung resonance frequency component having a relatively low frequency (0.5 to 2 Hz) included in the road surface state detection signal DR are respectively determined. Separated and extracted by high-pass filter processing and low-pass filter processing, these are respectively averaged by averaging processing, and it is determined whether or not the average value is larger than a predetermined set value, and the sprung resonance frequency component is smaller than the predetermined set value. Only when the unsprung resonance frequency component is larger than a predetermined set value is it judged that the road is small. At this time, if the vehicle is traveling on a good road or a bad road other than the small bad road, the process proceeds to step S8.

In step S8, the steering angle detection signal D
θ and the braking detection signal DB are read, and it is determined whether or not the values of these detection signals are both equal to or greater than a predetermined set value. The determination in this case is made by storing the normal control area I and the predetermined control area II, which are determined by the relationship between the braking detection value and the steering angle shown in FIG. It is determined in which control area.
At this time, if it belongs to the normal control region I, the process proceeds to step S9.

In step S9, the road surface condition detector 3
The detection signal DR of No. 3 is read to determine whether or not the vehicle is traveling on a rough road. The determination in this case is performed by performing the same processing as in step S7, and only when the sprung resonance frequency component and the unsprung resonance frequency component included in the vehicle height detection signal DR are larger than the predetermined set value, the road is judged as a bad road. judge. At this time, if the vehicle is traveling on a good road other than a bad road, the process proceeds to step S10.

In step S10, the steering angle detector 2
8 detection signal Dθ is read and steering wheel 2
It is determined whether or not 7 is in the neutral position, and when it is in the neutral position, it is determined that the vehicle is running straight without rolling and the process proceeds to step S11. In step S11, the detection signal DB of the braking detector 31 is read to determine whether or not the braking operation is being performed. If the braking operation is not being performed, the process proceeds to step S12.

In step S12, it is determined whether the vehicle speed V is substantially zero, and it is determined whether the vehicle is stopped. At this time, when the vehicle is traveling, the process proceeds to step S13. In step S13, the control command value CFi (i = s
, _M , _H ) and CRi, the maximum control command values CFmax and CRmax among them are selected, and these control command values CFmax and CRmax are stored in the maximum control command value storage area of the storage device 38c. Control goes to step S14.

In step S14, the detection signals DEa to DEd of the rotational position detectors 22 of the damping force variable shock absorbers 2a to 2d are read, and these are compared with the control command values CFmax and CRmax stored in step S13. It is determined whether or not they coincide with each other. If they do not coincide with each other, the process proceeds to step S15, and the command signals CS _F and CS for rotationally driving the electric motors 19 of the variable damping force shock absorbers 2a to 2d that do not coincide with each other are determined. _R is output through the interface circuit 38a to output circuits 39F and 39R
, And then to step S16. In this step S16, it is determined whether or not the electric motor 19 is normal, and if normal, the process returns to step S14.
In this case, the electric motor 19 determines the control command value CFi.
, CRi and the detection signals DEa, D of the rotational position detector 22.
When Eb and DEc and DEd do not match, the maximum control command values CFmax and CRmax and the rotational position detection signals DEa, DEb and DEc and DEd within a predetermined time (for example, 3 seconds) after the electric motor 19 is driven. When the two do not match, it is determined to be an abnormal state, and when the two match within a predetermined time, it is determined to be a normal state.

When the determination result of step S14 shows that the maximum control command values CFmax and CRmax and the detection signals DEa, DEb and DEc, DEd of the rotational position detector 22 match, the process proceeds to step S17. In step S17, it is determined whether or not the electric motor 19 is normal, and if normal, the process returns to step S1. The determination in this case is performed by determining whether or not the electric motor 19 is rotating when the rotation driving command of the electric motor 19 is not output, and when the electric motor 19 is not rotating, it is determined as normal. If it is rotating, it is determined to be abnormal.

If the result of the determination in step S1 is that the system is abnormal, the process proceeds to step S18, in which the damping force variable shock absorbers 2a, 2a for the front and rear wheels are provided.
Both b and 2c, 2d are controlled to the intermediate damping force M as the first set value, and then the process proceeds to step S19 to light or blink an abnormality warning lamp (not shown). Further, when the result of determination in step S2 is that the automatic / manual selection switch 35 is switched to the manual side, the process proceeds to step S2a to determine which selection position the damping force setting switch 36 is set to. 1
When the maximum damping force H, which is higher than the intermediate damping force M as the set value of, is set, the maximum damping force control command value CF _H
And CR _H stored in the manual command value storage area, then the electric motor 19 proceeds to step S2c, the manual command value control command value CF _H stored in the storage area
And CR _H and the detected signal DEa rotational position detector 22, DE
The electric motor 21 is driven so that b and DEc, DEd coincide with each other, and then the process proceeds to step S2d to determine whether the electric motor 21 is normal. If normal, the process returns to step S1. , And proceeds to step S18. Here, when the intermediate damping force M is set at step S2a, the process proceeds to step S2e, the step S2c after store intermediate damping force control command value CF _M and CR _M manual command value storage area Transition. When the minimum damping force S is set in step S2a, the process proceeds to step S2f, and the minimum damping force control command values CFs and CRs are stored in the manual command value storage area of the storage device 38c, and then the step S2c is executed.
Move to

Further, the determination result of step S4 is V ≧ V
If it is s, the process proceeds to step S4a, and the front wheel side damping force variable shock absorbers 2a and 2b necessary for ensuring maneuverability / stability and riding comfort are intermediately stored in the vehicle speed command value storage area of the storage device 38c. The control command values CFm and CRs for controlling the rear wheel side damping force variable shock absorbers 2c, 2d to the minimum damping force S are stored in the damping force M, and then the process proceeds to step S5.

Further, when the result of determination in step S5 is acceleration or deceleration, the process proceeds to step S5a, in which the rear portion of the vehicle body caused by acceleration is sunk into the acceleration / deceleration command value storage area of the storage device 38c. A control command for controlling the front and rear damping force variable shock absorbers 2a, 2b and 2c, 2d required to suppress the so-called nose dive in which the front portion of the vehicle body sinks during deceleration to an intermediate damping force M, respectively. shifts from store the value CF _M and CR _M in step S6.

Furthermore, when the result of the determination in step S6 is the bottoming state, the process proceeds to step S6a, and the front wheel side and the rear wheels necessary for suppressing the bottoming state are stored in the bottoming command value storage area of the storage device 38c. Side damping force variable shock absorbers 2a, 2b and 2c,
2d was stored control command value CF _M and CR _M controls respectively intermediate damping force M shifts from the step S7.

When the result of the determination in step S7 is a bad road, the process proceeds to step S13, and similarly when the result of the determination in step S8 belongs to the predetermined control region II at the time of large steering angle and large braking. , And proceeds to step S13. Further, when the result of the determination in step S9 is that the vehicle is traveling on a rough road, the damping force variable shock absorbers 2 on the front and rear wheels, which are optimum for traveling on a rough road, are stored in the bad road command value storage area.
After the control command values CF _M and CRM for controlling the a, 2b and 2c, 2d to the intermediate damping force _M are stored, the process proceeds to the step S13.

Furthermore, when the result of the determination in step S10 is the roll state, the process proceeds to step S10a, in order to exert the anti-roll effect of suppressing rolling of the vehicle in the roll command value storage area of the storage device 38c. shifts the damping force required front wheel side and rear wheel side variable shock absorber 2a, 2b and 2c, 2d from by storing a control command value CF _H and CR _H controls the maximum damping force H to step S11.

If the result of determination in step S11 is that the brake is in operation, the process proceeds to step S11a, and the braking command value storage area of the storage device 38c is
Control command values CF _H and CR _H for controlling the front and rear damping force variable shock absorbers 2a, 2b and 2c, 2d required to suppress the nose dive due to the depression of the brake pedal to the maximum damping force H, respectively. Is stored, and the process proceeds to step S12.

Further, when the result of determination in step S12 is that the vehicle is stopped, the process proceeds to step S12a, and the damping force variable shock absorbers 2a and 2d on the front and rear wheels are stored in the vehicle stop command value storage area of the storage device 38c. And 2c,
Control command values CF _H and CR for controlling 2d to a high damping force H
After storing _H , the process proceeds to step S13. Furthermore, step S2d, step S16 and step S1
When the determination result of 7 is the motor abnormality, the process proceeds to step S18.

Here, the processes of steps S3 to S7 and steps S9 to S17 are specific examples of the control means, and the process of step S8 is the determination means and step S.
The process of shifting from S8 to S13 is a specific example of the blocking unit. Next, the operation will be described. First, in order to selectively control the damping forces of the variable damping force shock absorbers 2a to 2d to desired values, the automatic / manual selection switch 35 is switched to the manual side and the damping forces H, M, and A desired damping force in S, for example an intermediate damping force M, is selected.

With this arrangement, when the arithmetic processing unit 38b of the control unit 37 executes the processing shown in FIG. 6, it is determined in step S1 whether the system is normal or not, and each command value storage area is stored. Is cleared, and then the process proceeds to step S2a via step S2. Since the damping force selection switch 36 has been set to the intermediate damping force M, the process proceeds to step S2e and the intermediate value is stored in the manual command value storage area. Control command values CF _M and C for setting the damping force M
R _M is stored, and then the process proceeds to step S2c to read the detection signals DEa to DEd of the rotational position detectors 22 provided on the damping force variable shock absorbers 2a to 2d, and read their rotational positions and control command values CF _M. and when the the CR _M there is a difference, until the two match, the electric motor 1
9 is rotationally driven, and then the process proceeds to step S2d to determine whether or not the electric motor 19 is normal. If normal, the process returns to step S1 to repeat these manual processes.

[0033] When switching the damping force selection switch 36 during the manual process to another damping force step S2b or S2f corresponding to the switch position is selected, the control command value CF _H corresponding to these, CR _H or CFs , CRs are stored in the manual command value storage area, and the electric motor 19 is rotationally driven in step S2c to control the damping forces of the variable damping force shock absorbers 2a to 2d to desired values.

When the automatic / manual selection switch 35 is switched to the automatic side from this manual processing state, the processing shifts from step S2 to step S3 and thereafter. That is, when the vehicle is stopped, the process proceeds to step S3 via step S1 and step S2, and the damping force variable shock absorbers 2a, 2b and 2c, 2d on the front wheel side and the rear wheel side are stored in the initial setting command value storage area.
Control values CFs and C that control the respective damping forces to the minimum damping force S.
Remember Rs. Then, step S4 to step S
After step 11, the process proceeds to step S12 to determine whether or not the vehicle is stopped. Since the vehicle is stopped, the process proceeds to step S4a and the damping force variable for the front wheels and the rear wheels is stored in the vehicle stop command value storage area. After the control command values CF _H and CR _H for controlling the damping forces of the shock absorbers 2a, 2b and 2c, 2d to the maximum damping force _H are stored, the process proceeds to step S13. Therefore, in this step S13, the stored contents of the respective command value storage areas are read and the maximum control command values CFmax and CRmax among the control command values stored therein are selected. In this case, the contents of the initial setting command value storage area are the control command values CFs and CRs for commanding the minimum damping force S,
Since the contents of the vehicle stop command value storage area are the maximum control command values CF _H and CR _H , and the contents of the other command value storage areas are cleared, the maximum control command values CF _H and CR _{H of the two} are set. Select and then control command value C in step S14
F _H and CR _H and the damping force control shock absorber 2a
Detection signals DEa to DEd of the rotational position detector 22 of .about.2d
If there is a difference, the process proceeds to step S15, and the damping force variable shock absorber 2a having the difference is compared.
The electric motor 19 of 2d is driven to rotate, and when the two coincide, the driving of the electric motor 19 is stopped.

In this way, when the electric motor 19 is rotationally driven, the shield cylinder 18 of the variable diaphragm 11 installed in the damping force variable shock absorbers 2a to 2d rotates, and the opening 16 of the shield cylinder 18 is rotated into the cylinder 15. While facing the through hole 12s of
Since the opening 17 faces the peripheral wall of the cylindrical body 15, the damping forces of the variable damping force shock absorbers 2a to 2d are controlled to the maximum damping force H. As a result, it is possible to prevent the vehicle body from shaking when the occupant gets in and out of the vehicle when the vehicle is stopped, and to improve the riding comfort. Next, in step S17, it is determined whether or not the electric motor 19 is normal, and then the process returns to step S1. Then, the above-described stop processing is continued until the vehicle starts traveling.

The vehicle starts traveling from this stop processing state.
By doing so, the road surface will be flat and smooth with less undulations.
When it is a good road such as a loading road,
In the acceleration state, it is determined in step S5 that the acceleration state is set.
Then, the process proceeds to step S5a, and the acceleration / deceleration command value storage area
, A control command value CF for commanding an intermediate damping force_MAnd CR _M
From step S6 to step S12
The control command value CF in the middle moves to step S13._MAnd C
R_MIs selected, and then in step S14 the control command value CF
_MAnd CR_MAnd the detection signal DEa of the rotational position detector 22
Compared with DEd to determine if they match,
Each damping force variable shock absorber 2a-2
d is controlled to the maximum damping force H, and the control command value CF_M
And CR _MAnd detection signals DEa to D of the rotational position detector 22
Since Ed does not match, go to steps S14 to S16.
After shifting, the electric motor 19 is rotationally driven to move the shield cylinder 18
Second rotation position R_MRotation to step S17
After making a transition to determine whether the electric motor 19 is normal,
Return to step S1. As a result, damping on the front and rear wheels
Variable force shock absorbers 2a, 2b and 2c, 2d
Maintaining the intermediate damping force M respectively, the scat that occurs when starting
Can be suppressed.

After that, when the vehicle shifts to a constant low speed running, the control command values CFs and CR for commanding the minimum damping force S are stored in the initial setting command value storage area in step S3.
After storing s, the process proceeds to step S13 through steps S4 to S12 to read the contents of each command value storage area and select those maximum control command values, but in this case, only the initial setting command value storage area Is the minimum damping force command value C
Since Fs and CRs are memorized, these are selected,
Control goes to step S14. In this step S14,
Since the damping force variable shock absorbers 2a, 2b and 2c, 2d on the front wheel side and the rear wheel side are controlled to the intermediate damping force M in the processing at the time of the previous start, respectively, the detection signals DEa of the rotational position detectors 22 thereof are controlled. , DEb and DEc, D
Since Ed and the control command values CFs and CRs do not match, step S15, step S16, and step S1
4 is repeated, the electric motor 19 is rotationally driven until they coincide with each other, then the process proceeds to step S17, it is determined whether the electric motor 19 is normal, and the process returns to step S1.

After that, when the vehicle is traveling at high speed, the process proceeds from step S4 to step S4a, and the damping force variable shock absorbers 2a, 2b on the front wheels are controlled to the intermediate damping force M in the high speed command value storage area. Control command value CF _{M to be set} and damping force variable shock absorber 2 on the rear wheel side
After storing the control command values CRs for controlling c and 2d to the minimum damping force S respectively, the electric motor 19 of each damping force variable shock absorber 2a to 2d is rotated in steps S13 to S15 through steps S6 to S12. Driven to the front wheel side damping force variable shock absorbers 2a, 2a
b is controlled to the intermediate damping force M, and the damping force variable shock absorbers 2c and 2d on the rear end side are controlled to the minimum damping force S, and then the process proceeds to step S17 to determine whether or not the electric motor 19 is normal. And returns to step S1. Thus, the damping force variable shock absorbers 2a and 2b on the front wheel side are set to the intermediate damping force M, and the damping force variable shock absorber 2c on the rear wheel side is set.
, 2d are controlled to the minimum damping force S, respectively, the steer characteristic of the vehicle becomes understeer, and the maneuverability and stability during high-speed traveling can be improved.

In this high speed running state,
Turn the ring wheel 27 to the right or left to turn.
If so, the high-speed driving state will not be changed.
Go to step S5a from S5 to store the high-speed command value
The intermediate damping force control command value CF_MAnd minimum damping force control
Command value CRs is stored, and then step S6 to step
After S9, the process proceeds to step S10, and this step S1
Since it is determined that the roll state is 0, go to step S10a.
Transition to the roll command value storage area, front wheel side and rear wheel side
Damping force variable shock absorbers 2a, 2b and 2c of
Control command value CF for controlling both 2d to maximum damping force H_HOver
And CR_HFrom step S11 and step S1
After 2, the process proceeds to step S13. This step S1
3, the control command value CFs and the initial setting command value storage area
And CRs in the high speed command value storage area_MOver
And CRs are controlled by the control command value CF in the roll command value storage area._H
And CR_HBy storing each of these,
Our maximum control command value CF _HAnd CF_HControl command value
After making a selection, the process proceeds to step S14. Accordingly
Then, in each of steps S14 to S16, each damping force can be applied.
Rotate the electric motor 19 of the shock absorbers 2a to 2d
Rotating to drive each damping force variable shock absorber 2a-2d
Is controlled to the maximum damping force H, and in step S17, the electric motor
After determining whether 19 is normal, go to step S1.
Return. In this way, when turning the vehicle,
Variable damping force shock absorbers 2a, 2b and 2c, 2
By controlling d to the maximum damping force H respectively,
On the other hand, Ann that suppresses rolling that involves a large posture change
It can exert a tyrolean effect.

Similarly, when the brake pedal 31 is depressed, the process proceeds from step S11 to step S11a, and the damping force variable shock absorbers 2a, 2b and 2c, 2d on the front and rear wheels are stored in the braking command value storage area. Command values CF _H and CR for controlling each to the maximum damping force H
_In the bottoming state, the control command values CF _M and CR for controlling the damping force variable shock absorbers 2a, 2b and 2c, 2d on the front and rear wheels to the intermediate damping force M are stored. _M is stored in the bottoming command value storage area, the maximum control command value is selected from the stored contents of each command value storage area in step S13, and correspondingly, each damping force variable shock absorber 2a is selected in steps S14 to S16. The damping force of 2d is changed, and it is determined in step S17 whether the electric motor 19 is normal, and then the process returns to step S1.

As described above, when a plurality of different control modes occur simultaneously on the basis of the detection signals from the detectors in a good road running state, the highest damping force control command value in the control modes is given priority. By selecting, it is possible to suppress the state in which there is a high possibility that the posture of the vehicle will change,
Optimal suspension control can be performed by improving maneuverability / stability and riding comfort.

Further, when the state of running on a good road is changed to the state of running on a small bad road such as a relatively flat gravel road with little undulation, in this state, the judgment result of step S7 is running on a small bad road. Directly from step S7 to step S1
Move to 3. Therefore, in this small rough road running state,
By only performing the vehicle speed determination in step S4, the acceleration / deceleration determination in step S5, and the bottoming state determination in step S6, the damping forces of the front and rear wheel side damping force variable shock absorbers 2a to 2d are reduced to the minimum damping. The damping force is controlled to either the force S or the intermediate damping force M, and the damping force variable shock absorbers 2a to 2d are determined as in the roll state determination in step S10 and the braking determination in step S11.
Is not performed to control the maximum damping force H, it is possible to attenuate the vertical vibration component due to the unsprung resonance frequency component transmitted to the vehicle body 3 via the wheels 1a to 1d when traveling on a rough road. Variable damping force shock absorber 2a
It is possible to control ~ 2d in a state where importance is placed on ride comfort.

Further, when the vehicle is in the turning braking state in which the steering and the braking are simultaneously performed in the running condition on the good road, and when the predetermined control region II in FIG. 7 is reached, the process proceeds from step S8 to step S13
Since the process for selecting the maximum damping force H is not performed as in the above, the damping force of the damping force variable CRT displays 2a to 2d is equal to or less than the intermediate damping force M which is the first set value, that is, the intermediate damping force M or Since it is controlled to the minimum damping force S, the posture change of the vehicle body is allowed, so that the load sharing on the turning outer wheel side does not increase sharply and the load sharing on the turning inner wheel side does not decrease sharply, and The difference in the shared load can be reduced, and the decrease in cornering power can be suppressed to ensure the ground contact, so that the side slip can be reduced and the steering stability can be improved.

Furthermore, when the vehicle travels on a bad road such as a gravel road with a lot of swells from a good road running condition or a small bad running condition, the process proceeds from step S1 to step S8 to step S9. Since it is determined that the road is a bad road in step S9a, the front wheel side and rear wheel side damping force variable shock absorbers 2 are stored in the bad road command value storage area.
a, 2b and 2c, step after storing the control command value CF _M and CR _M controls 2d respectively to the intermediate damping force M S
Move to 13. As a result, the control command values CF _M and _C R _M stored in step S9a reach the maximum values in the running condition on the rough road, so that each damping force variable shock absorber 2 is
The a to 2d damping force is fixed to the intermediate damping force M, the vertical vibration component transmitted from the road surface through the wheels 1a to 1d is large, and unsprung resonance is a problem in a bad road running state. The running performance of the vehicle can be improved by ensuring the grounding property between the wheels and the road surface and appropriate vibration damping property.

In the above embodiment, the case where the damping constants of the damping force variable shock absorbers 2a to 2b are controlled as the control characteristics of the suspension device has been described, but the present invention is not limited to this, and it is not limited to this. Since it suffices to allow a change in the vehicle body posture, even if the spring constant of the spring constant variable spring device 41 shown in FIG. 8 is controlled, the same action as in the case of controlling the damping constant can be obtained.

That is, the spring constant variable spring device 4
The reference numeral 1 communicates with a shock absorber 42, an air chamber 43 integrally formed on the upper portion of the shock absorber 42, and vertically expandable and contractible, and a three-way electromagnetic switching valve 44 closed in one direction to the air chamber 43, Further, it is composed of reservoir tanks 45 and 46 having different volumes, and an air supply device 49 which communicates with the reservoir tanks 45 and 46 via intake and exhaust valves 47 and 48.

This spring constant variable spring device 41 is used for the piston rod 42 of the shock absorber 42.
The upper end of a and the upper end of the air chamber 43 are attached to the vehicle body side member, respectively, and the lower end of the shock absorber 42 is attached to the wheel side member, so that they are mounted on the vehicle. Here, when the electromagnetic switching valve 44 is switched to the closed port side, the spring constant of the spring constant variable spring device 41 is determined only by the volume of the air chamber 43. Further, when the electromagnetic switching valve 44 is switched to the switching position where the air chamber 43 and the reservoir tank 45 are communicated with each other, the spring constant of the spring constant variable spring device 41 changes depending on the volume of the air chamber 43 plus the volume of the reservoir tank 45. It is determined. Further, when the electromagnetic switching valve 44 is switched to the switching position where the air chamber 43 and the reservoir tank 46 are communicated with each other, the spring constant of the spring constant variable spring device 41 changes depending on the volume of the air chamber 43 plus the volume of the reservoir tank 46. It is determined. Therefore, by controlling the switching of the electromagnetic switching valve 44, the air spring constant of the spring constant variable spring device 41 can be controlled to be switched among three stages of large, medium and small. The switching control of the spring constant variable spring device 41 is performed by switching the electromagnetic switching valve 44 by the exciting current from the control device 37. In FIG. 8, reference numeral 50 denotes an elastic body such as rubber, and 51
Is an air passage, 52 is another spring constant variable spring device 4
1 is an air passage communicating with 1. In addition, as a control characteristic of the suspension device, a roll rigidity variable stabilizer capable of changing the roll rigidity in three or more stages by supplying an exciting current may be applied to control the roll rigidity. A variable shock absorber, a variable spring constant spring device, and a variable roll stiffness stabilizer can also be used in combination.

Further, in the above embodiment, the case where the control characteristics such as the damping force, the spring constant and the roll rigidity of the suspension device can be switched in three stages has been described, but the present invention is not limited to this. The control characteristics can be switched in four or more steps. Further, the damping force variable shock absorbers 2a to 2d are configured as shown in FIG.
It is also possible to control the control characteristics steplessly by controlling the energization by the pulse-width-controlled exciting current output from 7. In this case, the damping force variable shock absorbers 2a to 2d in FIG. 8 are shown with the same reference numerals as the corresponding portions in FIG. 3, but one end is closed by the relief valve 60 in the cylindrical piston 9. The expansion side and contraction side orifices 61 and 62 are formed, and a fluid passage 63 communicating with the fluid chamber A is bored. On the other hand, in the center opening of the piston 9, a fluid passage 64 communicating with the fluid chamber B is formed.
The sleeve 65 in which the
A spool 66 is slidably fitted therein. The spool 66 has a recess 67 formed on the outer peripheral surface thereof so that the fluid passages 63 and 64 are communicated with each other. Also, the sleeve 65
A cylindrical case 68 is integrally fixed to the lower end of the case, an electromagnetic solenoid 69 is attached to the inner peripheral surface of the case 68, and the cylindrical magnetic yoke 7 is attached to the inner peripheral surface of the electromagnetic solenoid 69.
0 is fitted inside, a return spring 71 is housed inside, and its upper end is seated on the spool 66.

Therefore, when the electromagnetic solenoid 69 is in the non-energized state, as shown in FIG.
Is in a position biased upward by the return spring 71, and the recess 67 is in a position inconsistent with the opening end of the fluid passage 64, so that the fluid passages 63 and 64 are shut off and the fluid chambers A and B are orificeed. The damping force is maintained in the maximum state by communicating only with 61 and 62. Then, when a pulsed exciting current is supplied from the control device 37 to the electromagnetic solenoid 69 to energize it from this state, the spool 66 is lowered against the return spring 71 in accordance with the pulse width of the exciting current to move the fluid passage. The opposing area between 64 and the concave portion 67 is continuously changed, the fluid resistance between the fluid passages 63 and 64 is continuously changed, and the damping force can be continuously changed according to the pulse width of the exciting current. .

Further, in the above embodiment, the case where the suspension devices capable of changing the control characteristics are provided on both the front wheel side and the rear wheel side has been described, but the present invention is not limited to this.
The present invention can be applied to the case where the suspension device is mounted only on either the front wheel side or the rear wheel side. Furthermore, in the above-described embodiment, as the predetermined traveling condition, the case where both the small rough road traveling state and the traveling state in which the steering and the braking at the predetermined values or more are simultaneously performed are described. You may make it perform only one.

In the above embodiment, the case where the microcomputer 38 is applied as the control device has been described, but instead of this, electronic circuits such as a comparison circuit, a logic circuit, a command value setting circuit, and a selection circuit are combined. It can also be configured. Furthermore, the road surface state detection means may detect a wet road surface, a snow road surface, a sandy road surface, or the like instead of whether or not the road is a bad road as in the above-mentioned embodiment, and in these cases, not the ultrasonic distance measuring device, Other indirect detection means, such as a vertical stroke of the suspension and a raindrop sensor, may be used.

As described above, according to the present invention, when the vehicle is in a traveling state other than turning braking, the control means is used.
Suspension based on the detection signal of the running state detection means
The attitude of the vehicle body can be changed by switching the control characteristics of the device.
Since suppress reduction is at the same time went turning braking state more than predetermined steering and braking, that abolish inhibitory that the control characteristics of the suspension device is switched to the high stage by blocking means, permit the attitude of the vehicle body changes By doing so, it is possible to obtain an effect that the lowering of the cornering power can be suppressed to secure the grounding property, and the side slip can be reduced to ensure the steering stability.

[Brief description of drawings]

FIG. 1 is a basic configuration diagram showing an outline of the present invention.

FIG. 2 is a schematic configuration diagram showing an embodiment of the present invention.

FIG. 3 is a sectional view showing an example of a variable damping force shock absorber applicable to the present invention.

4 is a sectional view of FIG. 3, in which (a) is II of FIG.
FIG. 3B is an enlarged sectional view taken along line II-II in FIG.

FIG. 5 is a block diagram showing an embodiment of the present invention.

FIG. 6 is a flowchart showing a processing procedure of a control device applicable to the present invention.

FIG. 7 is a graph showing a control region determined by a steering angle detection value and a braking detection value.

FIG. 8 is a cross-sectional view showing another embodiment of the suspension device applicable to the present invention.

FIG. 9 is a sectional view showing still another embodiment of the suspension device applicable to the present invention.

[Explanation of symbols]

1a, 1b Front wheels 1c, 1d Rear wheels 2a-2d Damping force variable shock absorber (suspension device) 11 Variable throttle 19 Electric motor 22 Rotational position detector 26 Vehicle speed detector 28 Steering angle detector 30 Acceleration / deceleration detector 32 Braking detector 33 road surface state detector 37 control device 38 microcomputer 39F, 39R ... Output circuit 41 spring constant variable spring device (suspension device) 42 shock absorber 43 air chamber 44 electromagnetic switching valve 45, 46 reservoir tank 69 electromagnetic solenoid

Claims (1)

(57) [Claims] 1. A traveling state detecting means for detecting a vehicle traveling state including a steering state detecting means for detecting a steering state of a vehicle and a braking state detecting means for detecting a braking state of the vehicle, and the detection of the traveling state detecting means. Change the body posture based on the signal
Control means for switching and controlling the control characteristics of the suspension device in at least three stages of low, medium, and high, and steering and braking states in which the detection signals of the steering state detecting means and the braking state detecting means are above a predetermined level. Determination means for determining whether or not the result is equal to or more than a predetermined value.
A suspension control device for a vehicle , comprising: blocking means for blocking switching to a high stage by the control means when in a rudder and braking state .