JPS6136013A - Control device of suspension for vehicle - Google Patents

Abstract

PURPOSE:To prevent a driving feeling or the like from worsening, by controlling a suspension device, so that its control characteristic is prevented from being set to a predetermined set value or more, in no relation to a running condition when the decision result of a road surface condition is under a predetermined condition of bad road, wet road surface, etc. CONSTITUTION:A control device 37 equips detectors 26, 28, 30, 32 and 34, detecting a running condition of car speed, steering angle, acceleration and deceleration, brake and car height, while a road surface condition detector 33 detecting the condition of a running road surface. The control device 37 controls in accordance with a detection signal of the above detectors a control characteristic of damping force of a suspension device, including each damping force variable shock absorber 2a-2d, spring constant, roll rigidity, etc. to be switched in at least two steps or more. While the control device, when the road surface condition is decided under a predetermined condition (bad road, wet road surface, etc.), controls in no relation to a running condition detection signal the control characteristic of the suspension device so as to be prevented from being switched to a high side of the predetermined value or more.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a shock absorber with variable damping force, a variable spring constant spring device, a variable roll stiffness stabilizer, etc. The present invention relates to a vehicle suspension control device that improves the running performance and ride comfort of a vehicle on both good and bad roads.

[Conventional technology]

As a conventional vehicle suspension control device, there is one described in, for example, Japanese Patent Laid-Open No. 56-42739.

The conventional vehicle suspension control device described above detects vehicle running conditions such as the steering angle of the steering wheel, vehicle speed, and whether or not the brake pedal is operated, and increases or decreases the damping force of the shock absorber according to these detection signals. The vehicle is controlled to switch to prevent rolling or pitching of the vehicle.

[Problem that the invention seeks to solve]

However, in the conventional vehicle suspension control device described above, when the driving conditions for controlling the variable damping force shock absorber as a suspension device become complex, the damping force value determined by those driving conditions is Since the damping force variable shock absorber is controlled at the maximum value, it is uniformly controlled regardless of the road surface condition, so for example, when driving on a rough road such as a gravel road without undulations, the vehicle will not roll when cornering. When this occurs, the variable damping force shock absorber is controlled to a high damping force, which worsens the ride comfort when driving on rough roads, and also causes other vehicles to be If the damping force is controlled to be high depending on the driving conditions, the vehicle will undergo sudden attitude changes, which will affect maneuverability and
There was a problem that stability deteriorated. This tendency becomes especially noticeable in products such as those in JP-A No. 55-65741, in which the damping force of the shock absorber is switched in three stages (small, medium, large), or in products in which it is switched in more stages. .

[Means for solving problems]

In order to solve the above-mentioned problems, the present invention, as shown in the basic configuration diagram of FIG. A control means switches and controls control characteristics such as damping force, spring constant, and roll stiffness of the suspension device in at least two stages based on this detection signal, and a control means controls whether or not the detection signal of the road surface condition detection means meets a predetermined condition. The present invention is characterized by comprising a determining means for making a determination, and a blocking means for preventing the control characteristic of the suspension device from switching to a higher value that is equal to or higher than a predetermined value when the result of the determination is a predetermined condition.

[Effect]

This invention detects the driving state by performing steering and braking above a predetermined value when the vehicle is traveling on a rough road where the amplitude of vertical vibration of the vehicle body is relatively small, such as when traveling on a gravel road with few undulations. Even if a control signal is output so that at least one of the damping force, spring constant, and roll stiffness of the suspension device is equal to or higher than a predetermined value, when the road surface condition detection signal reaches the predetermined condition, The suspension prevents at least one of the damping force, spring constant, and roll stiffness of the suspension device from being controlled to exceed a predetermined set value, thereby preventing deterioration of ride comfort of the vehicle or sudden change in posture. The problem of the above-mentioned conventional example is solved by performing control.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

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, and FIGS. FIG. 5 is a block diagram showing an example of a control device applicable to the present invention, and FIG. 6 is a flowchart showing an example of a processing procedure of the control device. be.

First, to explain the configuration, in Fig. 2, la
, lb are front wheels, lc and ld are rear wheels, and 2a to 2d are variable damping force shock absorbers as suspension devices, and these variable damping force shock absorbers 2a to 2
d is installed between each of the wheels 1a to 1d and the vehicle body 3, and controls the damping force thereof to suppress changes in the posture of the vehicle body 3 and vibration components transmitted to the vehicle body 3 depending on the road surface condition.

As shown in FIG. 3, an example of the variable damping force shock absorbers 28 to 2d includes a piston 9 attached to the tip of the inner cylinder 8 of the piston rond 5.
a central opening 10 extending axially through the
A variable diaphragm 11 is formed at the upper end of the central opening 1o. As shown in FIGS. 4(a) and 4(b), this variable diaphragm 11 has three types of through holes 12 with different opening areas at the upper position.
h, 12112s are formed in the same horizontal plane with equal angular spacing, and 2 holes with different opening areas are formed at the lower position.
Seed holes 13h and 13m, and hole 12h.

A cylindrical body 15 is formed in the same horizontal plane facing 12m and has a central opening 14, and through holes 12h to I2S and I3h are fitted inside this cylindrical body 15.

13m, and a shielding cylinder 18 having one opening 16' and 17 at positions facing each other.

The shielding cylinder 18 is connected to the rotating shaft of an electric motor 19 installed in the piston rod 5 and is rotationally driven, and a return spring 2 is inserted between the openings 16 and 17 of the shielding cylinder 18.
A check valve 21 biased downward by 0 is provided.

The electric motor 19 is rotationally driven by drive currents from output circuits 39F and 39R of a 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 a rotating shaft. The detection signal is supplied to the control device 37 as a feed node signal.

Furthermore, the piston 9 has a fluid chamber A defined thereby.
An extension-side orifice 23 and a contraction-side orifice 24, which are relatively small holes, through which the working fluid C in B passes are bored.

Therefore, when the shielding cylinder 18 is in the first rotational position Rs shown in FIGS. 4(a) and (b), the openings 16 and 17 of the shielding cylinder each have the maximum opening area of the cylinder 15. Since it faces the through holes 12h and 13h, when the piston rod 5 moves in the contraction direction, the working fluid C from the fluid chamber B passes through the central opening 10 and flows into the fluid chamber A through the through holes 12h and 13h. At the same time, it also flows into the fluid chamber A through the contraction side orifice 24, and therefore,
Since the opening areas of the through holes 12h and 13h are large, fluid resistance is relatively small. On the other hand, when the piston port/7 door 5 moves to the extension side, the check valve 21 causes the through hole 12h to move.
Since the working fluid C is prevented from sinking into the fluid chamber A through the through hole 13h and the extension side orifice 23,
The damping force of the shock absorber as a whole is controlled to the minimum damping force S while causing a difference in damping force in the direction of contraction and extension of the piston rod 5.

Further, when the electric motor 19 is driven from this state to rotate the shielding cylinder 18 to the second rotation position Rr+, in this state, the openings 16 and 17 of the shielding cylinder 18 are aligned with the through holes 12m and 13vIl. Since they face each other and the opening area thereof is medium, the fluid resistance increases compared to the above case, and the damping force of the shock absorber is increased to an intermediate damping force M.

Further, when the electric motor 19 is driven from this state to rotate the shielding cylinder I8 to the 30th rotation position Rh, in this state, only the opening 16 of the shielding cylinder 18 is a through hole having the minimum opening area. 12s, the fluid resistance on the contraction side is maximum, and the through hole 12 on the expansion side
Since the working fluid C from the fluid chamber A is blocked by the check valve 21, the working fluid from the fluid chamber A flows through the extension side orifice 23.
The damping force of the shock absorber is increased to the maximum damping force H because the fluid resistance on the contraction side and the expansion side becomes maximum.

As shown in FIG. 2, the vehicle also includes a vehicle speed detector 26 that outputs a vehicle speed detection signal DV according to the output side rotation speed of a transmission (not shown) connected to the engine, and a steering wheel 27. A steering angle detector 28 detects the rotational position of the steering wheel and outputs a steering angle detection signal Dθ corresponding to the steering angle, and an acceleration/deceleration detection signal DA corresponding to the depression state of the accelerator pedal 32.
The acceleration/deceleration detector 30 detects the depression state of the brake pedal 31 and generates a braking detection signal DB according to the braking state.
a braking detector 32 that outputs a road surface condition detection signal DR, a road surface condition detector 33 configured with an ultrasonic distance measuring device that outputs a road surface condition detection signal DR according to the road surface condition, and a lower front surface of the front wheel 1a and rear wheel 1c of the vehicle body 3. vehicle height detectors 34F and 34R configured with ultrasonic distance measuring devices attached to the vehicle height detectors 34F and 34R, an auto/manual selection switch 35 for selecting whether suspension control is performed automatically or manually, and damping force selection in manual mode. A switch 36 is provided. In addition,
The vehicle speed detector 26. Steering angle detector 28, acceleration/deceleration detector 30. The brake detector 32 constitutes a running state detection means.

And each detector 26.28.30, 32.33.34
F, 34H detection signal and auto/manual selection switch 35. A switch signal from the damping force selection switch 36 is supplied to a control device 37 .

As shown in FIG. 5, the control device 37 includes a microcomputer 38 and an output circuit 39F connected to its output side.
and 39R includes at least an interface circuit 38a, an arithmetic processing device 38b, and a storage device 38c, and executes arithmetic processing according to the processing program shown in FIG.

That is, first, in step (2), 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 then step (2) is performed.
Then, it is determined whether the auto/manual selection switch 35 is switched to the auto side or the manual side. At this time, if it has been switched to the auto side, the process moves to step (3).

In this step (2), variable damping force shock absorbers 2a, 2b, and 2c are applied to the front and rear wheels.

2d to the minimum damping force S, a control command value CFs,
After storing CRs in the initial setting storage area of the storage device 38c, the process moves to step (2).

In this step (2), the detection signal DV of the vehicle speed detector 26 is read, the vehicle speed (2) is calculated based on this, and it is determined whether the vehicle speed (2) is equal to or higher than a predetermined set vehicle speed Vs. At this time, if the vehicle is traveling at a low speed less than the set vehicle speed Vs, the process moves to step (2).

In this step (2), the detection signal DA of the acceleration/deceleration detector 30 is
Based on this, it is determined whether the vehicle is decelerating or accelerating, and if the vehicle is traveling at a constant speed without decelerating or accelerating, the process moves to step (3).

In this step ■, vehicle height detector 3.4F and 34R
The detection signal is read and it is determined whether or not the vehicle is in a bottoming state where the vehicle passes through temporary irregularities and vertical vibrations occur in the vehicle body 3. If it is not in a bottoming state, step
to move to.

In this step (2), the detection signal D of the road surface condition detector 33 is
R is read, and it is determined whether the road surface on which the vehicle is traveling is a slightly rough road as a predetermined driving condition. In this case, the determination is made based on the relatively high frequency (10 to 12 Hz) sprung resonance frequency component and the relatively low frequency (0.5 to 2 Hz) unsprung resonance frequency component included in the road surface condition detection signal DR. The components are separated and extracted by bypass filter processing and q low-pass filter processing, each of these is averaged by averaging processing, and it is determined whether the average value is larger than a predetermined setting value. In addition, the road is determined to be slightly rough only when the unsprung resonance frequency component is larger than a predetermined set value. At this time, if the vehicle is traveling on a good road or a very bad road other than a slightly rough road, the process moves to step (2).

In this step (2), the steering angle detection signal Dθ and the braking detection signal DB are read, and it is determined whether the values of these detection signals are both greater than or equal to a predetermined set value.

In this case, the determination is made in the normal control area I and the predetermined control area ■ determined by the relationship between the detected braking value and the steering angle shown in FIG.
is stored in advance in a storage table in the storage device 38c, and it is determined in which control region the actual steering angle and braking detection value are located. At this time, if it belongs to the normal control area (2), the process moves to step (2).

In this step (2), the detection signal D of the road surface condition detector 33 is
R is read and it is determined whether or not the vehicle is driving on a rough road. In this case, the same process as in step (3) is performed to determine that the road is severely rough only when the sprung mass resonance frequency component and the sprung mass resonance frequency component included in the vehicle height detection signal DR are both greater than a predetermined set value. judge. At this time, if the vehicle is traveling on a good road other than a very bad road, the process moves to step [phase].

In this step [phase], the detection signal Dθ of the steering angle detector 28 is read, and it is determined whether or not the steering wheel 27 is in the neutral position. When the steering wheel 27 is in the neutral position, the vehicle is running straight without rolling. It was determined that
Move to step ■.

In this step (2), the detection signal DB of the brake detector 31 is read, and it is determined whether or not a braking operation is being performed. If the braking operation is not being performed, the process moves to step @.

In this step @, it is determined whether the vehicle speed V is approximately zero, and it is determined whether the vehicle is stopped. At this time, if the vehicle is running, the process moves to step 0.

In this step [phase], the control command values CFi (i=s, M, H) and CRi stored in each command value storage area are referred to, and the control command values CFmax and CRmax for the large amount of meat are selected. , these control command values CFmax and CRmax are stored in the maximum control command value storage area of the storage device 38c, and then the process moves to step (2).

In this step (2), the detection signal DEa"D of the rotational position detector 22 of each variable damping force shock absorber 2a to 2d is
Ed is read and compared with the control command values CFmax and CRmax stored in step 0 to determine whether they match. If they do not match, the process moves to step [Phase] to determine the mismatch. The command signals C3F and C3R for rotationally driving the electric motors 19 of the variable damping force shock absorbers 2a to 2d are output to the output circuits 39F and 39R via the interface circuit 38a, and then the process moves to step [phase]. In this step [phase], it is determined whether the electric motor 19 is normal or not, and if it is normal, the process returns to step (2). In this case, the judgment is
The electric motor 19 receives the control command values CFi and CRi and the detection signal DEa of the rotational position detector 22.

When DEb, DEc, and DEd do not match, the maximum control command values CFn+ax and CR11Iax and the rotational position detection signals DEa, DEb, DEc, DB, d
When they do not match, it is determined that the state is abnormal, and when the two match within a predetermined time, it is determined that the state is normal.

Moreover, the determination result of step (■) is the maximum control command value CFma
x and CRmax and the detection signal DE of the rotational position detector 22
When a, DBb and DEc, DEd match, the process moves to step O.

In this step O, it is determined whether the electric motor 19 is normal or not, and if it is normal, the process returns to step (2). The determination in this case is made by determining whether or not the electric motor 19 is rotating when the rotational drive command for the electric motor 19 is not output, and when the electric motor 19 is not rotating, it is determined that it is normal. When determining and rotating,
Determined as abnormal.

Further, when the determination result in step (2) is that the system is abnormal, the process moves to step [phase], and the variable damping force shock absorber 2a on the front wheel side and the rear wheel side.

2b, 2c, and 2d are all controlled to an intermediate damping force M, and then the process moves to step [phase] where an abnormality warning lamp (not shown) is lit or blinked.

Furthermore, if the determination result in step ■ is that the auto/manual selection switch 35 has been switched to the manual side, the process proceeds to step ■a, where it is determined to which selection position the damping force setting switch 36 is set; When the maximum damping force H is set, the maximum damping force control command values CFH and CRH are stored in the manual command value storage area, and then the process moves to step
9 is driven so that the control command values CFH and CRH stored in the manual command value storage area and the detection signals D Ea, D Eb, D Ec, and D Ed of the rotational position detector 22 match, and then step (2) is performed. Moving to C, it is determined whether the electric motor 21 is normal or not. If it is normal, the process returns to step (2), and if it is in an abnormal state, the process moves to step [phase]. Here, step ■
When the intermediate damping force M is set in step a, the process moves to step e and intermediate damping force control command values CFM and CR are set.
h is stored in the manual command value storage area, and then the process proceeds to step (2)C. Further, when the minimum damping force S is set in step (a), the process moves to step (f) and the minimum damping force control command values CFs and CRs are stored in the storage device 3.
After storing the manual command value in the manual command value storage area 8c, the process moves to step 2C.

Further, when the determination result in step (2) is V≧Vs, the process moves to step (2) a, and the information on maneuverability and stability is stored in the vehicle speed command value storage area of the storage device 38c.

A control command value CFm and After storing the CRs, the process moves to step (2).

Furthermore, when the determination result in step (2) is an acceleration or deceleration state, the process proceeds to step (a), and the storage device f3
In the acceleration/deceleration command value storage area of 8c, the front wheel side and rear wheel side information necessary to suppress the so-called skasoto, where the rear part of the vehicle body sinks in the acceleration state, or the so-called nose dive, where the front part of the vehicle body sinks in the deceleration state, is stored. After storing the control command values CFH and CRH for controlling the variable damping force shock absorbers 2a, 2b, 2c, and 2d to the maximum damping force H, the process moves to step (2).

Furthermore, when the determination result in step (2) is the bottoming state, the process moves to step (2) a, and the storage device 38
In the bottoming command value storage area c, variable damping force shock absorbers 2a on the front and rear wheels necessary to suppress the bottoming state are stored.

After storing control command values CFM and CRM for controlling damping forces 2b, 2c, and 2d respectively to intermediate damping force M, the process moves to step (2).

Also, when the judgment result in step ■ is that the road is slightly rough,
The process proceeds to step 0, and similarly, when the determination result in step (2) is that the steering angle is small and the braking is small, the process also proceeds to step 0.

Furthermore, based on the determination result of step (2) that driving is on a rough road, variable damping force shock absorbers 2a, 2b for front wheels and rear wheels that are optimal for driving on rough roads are stored in the rough road command value storage area.
After storing control command values CFM and CRM for controlling 2c and 2d to intermediate damping force M, respectively, the process proceeds to step 0.

Furthermore, when the determination result in step [phase] is a roll state, the process moves to step [phase] a, and an anti-roll effect for suppressing rolling of the vehicle is exerted in the roll command value storage area of the storage device 38c. The front wheel side and rear wheel side variable damping force shock absorbers 2a, 2 necessary for
After storing control command values CFH and CRH for controlling b, 2c, and 2d to the maximum damping force H, the process moves to step (2).

Further, when the determination result in step (2) is that the brake is being applied, the process moves to step (2) a, and the braking command value storage area of the storage device 38c stores the front wheel necessary for suppressing nose dive due to depression of the brake pedal. After storing the control command values CFH and CRH for controlling the variable damping force shock absorbers 2a, 2b, 2c, and 2d on the side and rear wheel sides to the maximum damping force H, respectively, the process moves to step @.

-Furthermore, when the determination result in step @ is that the vehicle is stopped, the process proceeds to step @a, and the variable damping force shock absorbers 2a, 2d and After storing control command values CFH and CRH for controlling 2c and 2d to a high damping force H, the process moves to step [phase].

Furthermore, when the determination results in step d, step [phase], and step O indicate that the motor is abnormal, the process moves to step @.

Here, the processes from step ■ to step ■ and step ■ to step O are specific examples of the control means, step ■ or step ■ is a specific example of the determination means, and the process moves from step ■ or step ■ to step @. Processing is a specific example of the blocking means.

Next, the effect will be explained. First, in order to selectively control the damping force of the variable damping force shock absorbers 28 to 2d to a desired value, switch the auto/manual selection switch 35 to the manual side, and use the damping force selection switch 36 to selectively control the damping force H, M. .

Select a desired damping force in S, for example, intermediate damping force M.

In this way, the arithmetic processing unit of the control device 1E37! 3
When the process shown in FIG. 6 is executed in step 8b, it is determined whether the system is normal or not in step 2, and the storage contents of each command value storage area are cleared, and then 1. The process moves to step ■a via step ■, and since the damping force selection switch 36 has selected the intermediate damping force M, the process moves to step ■e, and the intermediate damping force M is set in the manual command value storage area M. Store control command values CFM and CRM,
Next, proceed to step ■C, and set each damping force variable
The detection signals DEa"DEd of the rotational position detectors 22 provided in the quad absorbers 28 to 2d are read, and if there is a difference between these rotational positions and the control command values CFM and CRr+, the electric motor 19 The electric morph 19 is driven to rotate, and then the process proceeds to step (2) d, where it is determined whether or not the electric morph 19 is normal. If it is normal, the process returns to step (2) and these manual processes are repeated.

If the damping force selection switch 36 is switched to another damping force during this manual processing, step ■b or ■f is selected according to the switching position, and the corresponding control command value CF+, CR)I or CFs.

CRs is stored in the manual command value storage area, and in step 2C, the electric motor 19 is rotationally driven to control the damping force of the variable damping force shock absorbers 2a to 2d to a desired value.

Furthermore, when the auto/manual selection switch 35 is switched to the auto side from this manual processing state, the process shifts from step (2) to automatic processing from step (2) onwards.

That is, when the vehicle is stopped, steps ■,
The process moves to step (2) through step (2), and the control command values for controlling the variable damping force shock absorbers 2a, 2b, 2c, and 2d on the front and rear wheels to the minimum damping force S are stored in the initial setting command value storage area 'J. Store CFS and CRs. Next, the process moves to Step Nob@ through Steps 2 to 11 to determine whether or not the vehicle is stopped. Since the vehicle is stopped, the process moves to Step 2a and the information is stored in the stop command value storage area. Maximum damping force H
After storing the control command values CFH and CRH to be controlled, the process moves to step 0. Therefore, this step 0
Then, the contents of each command value storage area are read, and the maximum control command value CF m among the control command values stored therein is read.
Select ax and CRmax. In this case, the contents of the initial setting command value storage area are the control command values CFs and CRs that command the minimum damping force S, the contents of the stop command value storage area are the maximum control command values CFH and CRH, and the other command values Since the contents of the storage area have been cleared, select the maximum control command values CFH and CRH of both, and then use the steering knob ■ to set the control command values CFH and CRH and the values for each variable damping force shock absorber 2a to 2d. Rotational position detector 22
Detection signals DEa=DEd are compared, and if there is a difference, the process moves to step [phase], and the electric motor 19 of the variable damping force shock absorber 2a to 2d having the difference is rotated, and the two match. At this point, the drive of the electric motor 19 is stopped. As described above, when the electric motor 19 is rotationally driven, the shielding cylinder 18 of the variable diaphragm 11 installed in the variable damping force shock absorbers 28 to 2d rotates, and the opening 16 opens into the through hole of the cylinder 15. Along with facing 12s,
Since the opening 17 faces the peripheral wall of the cylindrical body 15, the damping force of the variable damping force shock absorbers 2a to 2d is controlled to the maximum damping force H. As a result, it is possible to prevent the vehicle body from shaking when a passenger gets on and off the vehicle when the vehicle is stopped, thereby improving ride comfort. Next, in step O, it is determined whether the electric motor 19 is normal or not, and then the process returns to step (2). The above-described stopping process is continued until the vehicle starts traveling.

When the vehicle starts running from this stop processing state, if the road surface is flat with few undulations and is a good road such as a smooth paved road, the acceleration state at the time of starting is determined to be an acceleration state in step Therefore, step ■
After moving to step a, the control command values CFM and CRM for commanding the intermediate damping force are stored in the acceleration/deceleration command value storage area, and then the flow moves to step 0 through steps ■ to step @ to store the intermediate control command value CFr+. and CRM, and then in step (2), the control command values CFr+ and CRM are compared with the detection signals DEa to DEd of the rotational position detector 22, and it is determined whether they match. Since the variable force shock absorbers 28 to 2d are controlled to the maximum damping force H, and the control command values CFM and CRM do not match the detection signal DEaNDEd of the rotational position detector 22,
The process moves to steps [phase] to [phase] to rotationally drive the electric motor 19 to rotate the shielding cylinder 18 to the second rotation position RM, and then moves to step @ to determine whether the electric motor 19 is normal. Determine if it is true and then return to step ■. As a result, the variable damping force shock absorbers 2a, 2 on the front wheel side and the rear wheel side
By maintaining b, 2c, and 2d at intermediate damping force M, it is possible to suppress scuts that occur when the vehicle starts moving.

After that, when the vehicle shifts to relatively low constant speed driving,
In step ■, the minimum damping force S is stored in the initial setting command value storage area.
After storing the control command values CFs and CRs for commanding, the process moves to step 0 via Step 0 to Step @, reads the contents of each command value storage area, and selects the maximum control command value. Since only the initial setting command value storage area stores the minimum damping force command values CFs and CRs, these are selected and the process moves to step [phase].

In this step (2), the variable damping force shock absorbers 2a, 2 on the front and rear wheels are used in the process at the time of the previous start.
b, 2c, 2d, are each controlled to an intermediate damping force M, so that the detection signal DE of the rotational position detector 22 is
Since a, DEb, DEc, and DEd do not match the control command values CFs and CRs, step [phase], step [phase], and step [phase] are repeated to rotate the electric motor 19 until they match. After driving, the process moves to step @, determines whether or not the electric motor 19 is normal, and returns to step (2).

After that, when the vehicle is running at high speed, step ■
The process moves to step (a), and the variable damping force shock absorbers 2a, 2b for the front wheels are stored in the high-speed command value storage area.
After storing the control command value CFm for controlling the damping force M to the intermediate damping force M and the control command value CRs for controlling the variable damping force shock absorbers 2c and 2d on the rear wheel side to the minimum damping force S, step Step 0 ~ Step■
The electric motor 19 of each of the variable damping force shock absorbers 2a to 2d is rotationally driven to set the variable damping force shock absorbers 2a, 2b on the front wheel side to the intermediate damping force M, and the variable damping force shock absorbers 2c, 2d on the rear end side. After controlling the damping force S to the minimum damping force S, the process moves to step O, and the electric motor 19
It is determined whether or not it is normal, and the process returns to step (2). In this way, the variable damping force shock absorber 2a on the front wheel side,
2b to the intermediate damping force M, and the variable damping force shock absorbers 2c and 2d on the rear wheel side to the minimum damping force S, respectively.
The vehicle's steering characteristics become understeer, improving maneuverability and stability when driving at high speeds.

Then, in this high-speed running state, if the steering wheel 27 is turned to the right or left to enter a turning state, the high-speed running state will not be changed, so the process moves from step ■ to step ■a, and the high-speed command value storage area is stored. The intermediate damping force control command value CFr1 and the minimum damping force control command value CRs are memorized, and then the process moves to step [phase] through step 0 to step ■. Since it is determined that the roll state is in this step [phase], step Shifting to [phase] a, control command values CFH and CRH for controlling both the front wheel side and rear wheel side variable damping force shock absorbers 2a, 2b, 2c, and 2d to the maximum damping force H are stored in the roll command value storage area. is memorized and then moves to step @ via step 0 to step [phase]. In this step @, control command values CFs and CR8 are stored in the initial setting command value storage area, control command values CFM and CRs are stored in the high speed command value storage area, and control command values CFH and CR,+ are stored in the roll command value storage area. Since these are stored, the maximum control command values CFH and CFH are selected as control command values, and then the process moves to step 0. Therefore, in steps ① to [phase], the electric motor 19 of each variable damping force shock absorber 2a to 2d is rotationally driven to control each variable damping force shock absorber 2a to 2d to the maximum damping force H, and in step O After determining whether the electric motor 19 is normal, the process returns to step (2). In this way, the variable damping force shock absorbers 2a, 2b, and 2c on the front wheel side and the rear wheel side when the vehicle turns.

2d to the maximum damping force H, the vehicle body 3
It is possible to exert an anti-roll effect that suppresses rolling that is accompanied by a large change in posture.

Similarly, when braking by depressing the brake pedal 31,
Moving from step (2) to step Oa, variable damping force shock absorbers 2a, 2b, and 2c for the front and rear wheels are stored in the braking command value storage area.

2d to the maximum damping force H, and in the bottoming state, step
Moving on to the front wheel side and rear wheel side variable damping force shock absorbers 2a, 2b and 2c.

The control command values CFM and CRh for controlling the damping force M to the intermediate damping force M are respectively stored in the bottoming command value storage area, and in step 0, the maximum control command value is selected from the contents stored in each command value storage area. Accordingly, the damping force of each variable damping force shock absorber 2a to 2d is changed in steps [phase] to step [phase], and in step O, it is determined whether the electric motor 19 is normal or not, and then the process returns to step (■). .

In this way, when a plurality of different control modes occur simultaneously based on the detection signals from each detector under a good road driving condition, the highest damping force control command value among the control modes is selected preferentially. Accordingly, it is possible to suppress a state in which there is a high possibility of causing a change in the posture of the vehicle, and it is possible to perform optimal suspension control with improved maneuverability, stability, and ride comfort.

In addition, when the state of driving on a good road changes to the state of driving on a relatively flat gravel road with few undulations, the judgment result of step (■) becomes "driving on a slightly rough road" in this state, so from this step (■) Move directly to step @. Therefore, when driving on a slightly rough road, only the vehicle speed determination in step ■, the acceleration/deceleration determination in step ■, and the bottoming state determination in step ■ are performed, and the shock absorbers with variable damping force on the front and rear wheels are The damping forces 2a to 2d are controlled to either the minimum damping force S or the intermediate damping force M, and each damping force is Since the process of controlling the variable shock absorbers 2a to 2d to the maximum damping force H is not performed, the vertical vibration component due to the unsprung resonance frequency component transmitted to the vehicle body 3 via each wheel 1a to 1d when driving on a rough road is attenuated. This makes it possible to control the variable damping force shock absorbers 2a to 2d in a state that emphasizes riding comfort.

Furthermore, when steering and braking are simultaneously performed while driving on a good road and the predetermined control region (■) shown in FIG. Since this is not done, sudden changes in the attitude of the vehicle can be prevented, and maneuverability and stability can be ensured.

Furthermore, when the driving condition changes from a good road driving condition or a slightly rough road driving condition to a driving condition on a very rough road such as a gravel road with many undulations, the process moves to step ■ through steps ■ to step ■, and in this step Since it is determined that the vehicle is on a road, the process moves to step (a), and the front wheel side and rear wheel side variable damping force shock absorbers 2a, 2b, 2c, 2d are stored in the severe rough road command value storage area.
After storing the control command values CFr+ and CRM for controlling the damping force M to the intermediate damping force M, the process moves to step 0. As a result, when driving on a very rough road, the control command values CFM and CRr+ stored in step (a) are at their maximum values, so the damping force of each variable damping force shock absorber 2a to 2d is fixed to the intermediate damping force M. Therefore, wheel 1a-1 is removed from the road surface.
It is possible to improve the running performance of the vehicle by ensuring the ground contact between the wheels and the road surface in a very rough road running condition where the vertical vibration component transmitted through d is large and unsprung resonance becomes a problem.

In the above embodiment, a case has been described in which variable damping force shock absorbers 2a to 2d are applied as a suspension device, but the invention is not limited to this, and a variable spring constant spring device 41 shown in FIG. 8 may be applied. You can also.

That is, the variable spring constant spring device 41 includes a shock absorber 42, an air chamber 43 that is integrally formed in the upper part of the spring and is expandable and retractable in the vertical direction, and a spring in the air chamber 43.
Reservoir tanks 45.46 communicating through a three-way electromagnetic switching valve 44 whose direction is closed and having different volumes, and intake/exhaust valves 47.4 connected to these reservoir tanks 45.46.
8, and an air supply device 49 communicating with each other via a.

This variable spring constant spring device 41 attaches the upper end of the piston rod 42a of the shock absorber 42 and the upper end of the air chamber 43 to the vehicle body side member, and also attaches the lower end of the shock absorber 42 to the wheel side member. installed on the vehicle.

Here, when the electromagnetic switching valve 44 is switched to the closed boat side, the spring constant of the variable spring constant spring device 41 is determined only by the volume of the air chamber 43. Moreover, when the electromagnetic switching valve 44 is switched to the switching position that communicates the air chamber 43 and the reservoir tank 45,
The spring constant of the variable spring constant spring device 41 is determined by the volume of the air chamber 43 plus the volume of the reservoir tank 45. Furthermore, the electromagnetic switching valve 44 is connected to the air chamber 43.
When the switch position is switched to communicate the air chamber 43 with the reservoir tank 46, the variable spring constant spring device 41
The spring constant of is determined. Therefore, the electromagnetic switching valve 44
By switching and controlling the air spring constant of the variable spring constant spring device 41, it is possible to switch and control the air spring constant of the variable spring constant spring device 41 into three stages: large, medium, and small. Switching control of the variable spring constant spring device 41 is performed by switching the electromagnetic switching valve 44 using an excitation current from the control device 37. In addition, in FIG. 8, 50 is an elastic body such as rubber, 51 is an air passage, and 52 is another spring constant variable spring device 41.
It is an air passageway that communicates with the In addition, as a suspension device, a roll stiffness variable stabilizer that can change roll stiffness in three or more stages by supplying an excitation current can also be applied, a damping force variable shock absorber, a spring constant variable spring device, and a roll A variable stiffness stabilizer can also be used in combination.

Furthermore, in the above embodiment, a case has been described in which the control characteristics such as the damping force, spring constant, and roll rigidity of the suspension device can be switched in three stages.
The control characteristics are not limited to this, and the control characteristics may be configured to be switchable in four or more stages.Furthermore, the variable damping force shock absorbers 28 to 2d may be configured as shown in FIG. By energizing the solenoid with a pulse width-controlled excitation current output from the control device 37, the control characteristics can be controlled steplessly. In this case, the variable damping force shock absorber 2 shown in FIG.
In a to 2d, parts corresponding to those in FIG.
．． 62 is formed, and a fluid passage 63 communicating with the fluid chamber A is bored. On the other hand, a sleeve 65 having a fluid passage 64 communicating with the fluid chamber B is fitted into the center opening of the piston 9, and a spool 66 is slidably fitted into the sleeve 65. The spool 66 has a recess 67 formed on its outer peripheral surface to communicate the fluid passages 63 and 64. Further, a cylindrical case 68 is integrally fixed to the lower end of the sleeve 65.
An electromagnetic solenoid 69 is attached to the inner circumferential surface of the electromagnetic solenoid 69, and a cylindrical magnetic yoke 70 is fitted into the inner circumferential surface of the electromagnetic solenoid 69. A return spring 71 is housed inside the magnetic yoke 70, and its upper end is seated on the spool 66. are doing.

Therefore, when the electromagnetic solenoid 69 is in a non-energized state, the spool 66 is in a position where it is urged upward by the return spring 71, as shown in FIG. Therefore, the fluid passages 63 and 64 are cut off, and the fluid chambers A and B are in the same position.
The damping force is maintained at its maximum by communicating only through the orifices 61 and 62. Then, when the electromagnetic solenoid 69 is energized by supplying a pulsed excitation current from the control device 37 from this state, the spool 66 is lowered against the return spring 71 according to the pulse width of the excitation current, and the fluid passage 64 and the recess 67 are continuously changed, the fluid resistance between the fluid passages 63 and 64 is continuously changed, and the damping force can be changed steplessly according to the pulse width of the exciting current. .

Furthermore, in the above embodiment, a suspension device that can change control characteristics is provided on both the front wheel side and the rear wheel side, but the present invention is not limited to this. The present invention can also be applied when a suspension device is attached to a vehicle.

Furthermore, in the above embodiment, as the predetermined driving conditions, a case has been described in which both a slightly rough road driving condition and a driving condition in which steering and braking of a predetermined value or more are simultaneously controlled. Only one of them may be performed.

Further, in the above embodiment, the case where the microcomputer 38 is applied as the control device has been explained.
Alternatively, it may be constructed by combining electronic circuits such as a comparison circuit, a logic circuit, a command value setting circuit, and a selection circuit.

Furthermore, the road surface condition detection means may detect wet road surfaces, snowy road surfaces, sandy road surfaces, etc., instead of determining whether the road is rough as in the above embodiments, and in these cases, instead of using an ultrasonic distance measuring device, Other indirect detection means may also be used, such as suspension up and down strokes, raindrop sensors, etc.

〔Effect of the invention〕

As explained above, according to the present invention, there is provided a suspension device capable of switching control characteristics into at least two or more stages, and a suspension device that can be used to accelerate, decelerate, and
The system includes a control means for detecting driving conditions such as steering based on a detection signal from one driving condition detector, and a means for detecting the state of the road surface, and the preventing means is configured to prevent braking by a predetermined value or more.

Regardless of the detection signal of the running condition such as steering, it is determined whether the detection signal of the road surface condition meets a predetermined condition. At a certain time, regardless of the driving condition, the damping force, spring constant, roll stiffness, and other control characteristics of the suspension system are set to predetermined values (large damping force on the upper side).
Since the configuration is configured such that the suspension is not set above the level above, suspension control that emphasizes ride comfort can be performed when driving on a rough road, and it is possible to prevent discomfort from being caused to the occupants. When steering and braking are performed by a value greater than or equal to the value, it is possible to prevent a sudden change in the attitude of the vehicle, and the driving performance of the vehicle can be improved.

[Brief explanation of the drawing]

FIG. 1 is a basic configuration diagram showing an overview of this invention, FIG. 2 is a schematic configuration diagram showing an embodiment of this invention, and FIG. 3 is a cross-sectional diagram showing an example of a variable damping force shock absorber that can be applied to this invention. Figures 4(a) and (b) are respectively I-
5 is a block diagram showing an embodiment of the present invention, FIG. 6 is a flowchart showing the processing procedure of a control device applicable to the present invention, and FIG. A graph showing the control area determined by the detected steering angle value and the detected braking value, and FIGS. 8 and 9 are cross-sectional views showing other embodiments of the suspension device applicable to the present invention, respectively. 1a, 1b...front wheel, lc, ld...
Rear wheel, 2a to 2d... Variable damping force shock absorber (suspension device), 11-... Variable aperture, 19... Electric motor, 22...
Rotational position detector, 26...Vehicle speed detector, 28.
...Steering angle detector, 3o old... acceleration/deceleration detector,
32...Brake detector, 33.Old...Road surface condition detector, 34F, 34R...Vehicle height detector, 35.
...Auto/manual selection switch, 36...
... Damping force selection switch, 37 ... Control device, 38 ... Microcomputer, 39F,
39R...output circuit, 41...variable spring constant spring device (suspension device), 42...
... Shock absorber, 43 ... Air chamber, 44 ... Solenoid switching valve, 45.46 ...
・・IJ f-Batank, 63. 64・Old・・Fluid passage, 66・・・Spool, 67・・・Recessed part,
69... Electromagnetic solenoid.

Claims (1)

[Claims] road surface condition detection means for detecting the state of the road surface; driving condition detection means for detecting the vehicle running condition; and control characteristics such as damping force, spring constant, and roll stiffness of the suspension device in at least two or more levels based on the detection signal. and determining means for determining whether or not the detection signal of the road surface condition detection means satisfies a predetermined condition. A suspension control device for a vehicle, characterized in that it is provided with a blocking means that prevents the control characteristic of the suspension device from switching to a higher value that exceeds a predetermined value regardless of how the control characteristic of the suspension device is controlled.