JPH06270631A - Suspension control device - Google Patents

Abstract

PURPOSE:To prevent influence of failure occurrence upon the maneuvering stability by making control signal formation for the control mode of a control means only with the vertical acceleration sensing value when failure is sensed by a sensing means for the relative displacement of a suspension device with the car body. CONSTITUTION:A controller 4 is fed with signals given by vertical acceleration sensors 51FL-51RR between the car body and wach wheel and stroke sensors 52FL-52RR of a shock absorber. The signal passed through an input interface circuit 56a are fed to a computational processing device 56c which judges if any failure exists in the stroke sensors, and if normal, the damping factor for conducting the skyhook control is decided, and if in failure, the output value of the failed stroke sensor is not used, but the damping factor for performing the approximative skyhook control is decided, and step motors 41FL-41RR are driven in such a way as corresponding to the decided damping factor so as to control the shock absorber. Even though relative displacement sensing means goes in failure, change of the suspension characteristics can be done without influencing the maneuvering stability or the comfortableness.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a suspension control device for performing so-called semi-active control in which the control characteristics of a suspension are controlled based on the displacement speed of the vehicle body and the relative speed between the vehicle body and the wheels.

[0002]

2. Description of the Related Art As a conventional suspension control device, for example, JP-A-61-360 previously proposed by the applicant of the present application.
There is one described in Japanese Patent No. 13. In this conventional example, a damping force variable shock absorber that can switch the damping force between high, medium and low levels by a drive motor is used, and the drive motor is used for running conditions such as a vehicle height detector and a road surface condition detector. And the road surface condition detection means, the control is performed based on the detection signal to suppress the change in the posture of the vehicle body. When a system abnormality occurs due to an abnormality of various sensors or an abnormality of the control system, a damping force variable shock is generated. By controlling the absorber to an intermediate damping force and turning on the abnormality warning lamp, the damping force control is stopped.

[0003]

However, in the above-mentioned conventional suspension control device, when a system abnormality such as a sensor abnormality occurs, the damping force control is stopped and the damping force of the damping force variable shock absorber is reduced. Since it is fixed to the intermediate damping force, it is possible to change from the road surface when there is a large change in the posture of the vehicle body, such as when traveling on a bad road, or when traveling on a gravel road. If the damping force control is suddenly stopped when the vibration input is large, there is an unsolved problem that the posture of the vehicle body changes, the steering stability deteriorates, and the riding comfort deteriorates.

Therefore, the present invention has been made by paying attention to the unsolved problem of the above-mentioned conventional example, and controls when an abnormality occurs in the relative displacement detecting means for detecting the relative displacement between the vehicle body and the wheels. An object of the present invention is to provide a suspension control device capable of continuing the posture change suppression control of the suspension device by changing the mode.

[0005]

In order to achieve the above object, a suspension control device according to the present invention is interposed between a vehicle body side member and a wheel side member as shown in the basic configuration diagram of FIG. A suspension device capable of changing a vehicle body posture change suppression characteristic according to an input control signal, a vertical acceleration detecting means for detecting a vertical acceleration at a position of the suspension device of the vehicle body, the vehicle body side member and the wheel side Relative displacement detection means for detecting relative displacement between members, and the control signal for suppressing a change in posture of the vehicle body based on the vertical acceleration detection value of the vertical acceleration detection means and the relative displacement detection value of the relative displacement detection means. In the suspension control device including a control unit that outputs the abnormal output, the abnormality detection unit that detects an abnormal state of the relative displacement detection unit differs from the abnormality detection unit. The upon detecting, and characterized in that a control changing means for changing to form a control signal based on the control mode by the control means only in the vertical acceleration detection value.

[0006]

In the present invention, when the vertical acceleration detecting means and the relative displacement detecting means are normal, the control means forms a control signal based on the vertical acceleration detected value and the relative displacement detected value to control the suspension device. By doing so, for example, the skyhook control is performed to suppress the change in the posture of the vehicle body and the vibration input from the road surface is cut off, but when an abnormality occurs in the relative displacement detection means, the control is performed based only on the vertical acceleration detection value. By forming a signal,
The skyhook approximation control is performed and the attitude change suppression control of the vehicle body is continued.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 is a schematic configuration diagram showing an embodiment of the present invention, in which the damping force variable shock absorber 3 constitutes a suspension device between each of the wheels 1FL to 1RR and the vehicle body 2.
FL to 3RR are arranged, and a step motor 41 for switching the damping force of these damping force variable shock absorbers 3FL to 3RR
FL to 41RR are controlled by control signals from the controller 4 described later.

Variable damping force shock absorber 3FL to 3RR
As shown in FIGS. 3 to 7, the piston is configured as a twin-tube type gas-filled strut type having a cylinder tube 7 composed of an outer cylinder 5 and an inner cylinder 6, and the inside of the inner cylinder 6 is in sliding contact with the piston. 8 define upper and lower pressure chambers 9U and 9L. 4 to 7, the piston 8 includes a cylindrical lower half body 11 having a central opening 10 formed in the inner peripheral surface of a seal member 9 that is slidably contacted with the inner cylinder 6 on the outer peripheral surface. It is composed of an upper half body 12 fitted in the lower half body 11.

In the lower half body 11, an expansion side oil flow path 13 is formed so as to vertically penetrate therethrough, and a sealing member 9 is provided downward from the upper surface side.
Hole 14a having a diameter larger than that of the expansion-side oil passage 13 and extending from the outer peripheral surface of the cylindrical body 11 to the hole 14a.
The pressure side oil flow passage 14 formed by a hole portion 14b that is formed by communicating with the bottom portion of a, the annular grooves 15U and 15L formed at the upper and lower open ends of the central opening 10, and formed on the upper surface side. A long groove 16 that communicates with the annular groove 15U and the expansion-side oil passage 13 is formed, and a long groove 17 that is formed on the lower surface side and that communicates with the annular groove 15L is formed. The long groove 17 is closed by the expansion side disk valve 18, and the upper end side of the compression side oil flow path 14 is closed by the compression side disk valve 19.

The upper half 12 has a small-diameter shaft portion 21 fitted in the central opening 10 of the lower half body 11 and the shaft portion 2.
1 and a large diameter shaft portion 22 having a diameter smaller than the inner diameter of the inner cylinder 6 integrally formed at the upper end of the small diameter shaft portion 21 and the lower end surface of the small diameter shaft portion 21 at the center position of the small diameter shaft portion 21 and the large diameter shaft portion 22. Hole 23a reaching from the side to the middle portion of the large-diameter shaft portion 22 and a hole portion 23b having a smaller diameter than the hole portion 23a communicating with the upper end side of the hole portion 23a.
And a through hole 23 composed of a hole portion 23c having a larger diameter than this and communicating with the upper end side of the hole portion 23b is formed, and a radius is provided at a position facing the annular grooves 15U and 15L of the small diameter shaft portion 21, respectively. Pair of through holes 24 penetrating to the inner peripheral surface side in the direction
a, 24b and 25a, 25b, and an arc-shaped groove 2 communicating with the upper end side of the hole portion 23a of the large-diameter shaft portion 22.
6 is formed, and an L-shaped pressure side oil flow passage 27 that connects the arc-shaped groove 26 and the lower end surface is formed, and the lower end surface opening portion of the pressure side oil flow passage 27 has a pressure side disk valve 28.
Is blocked by.

The lower half body 11 and the upper half body 12 are located below the lower half body 11 of the small diameter shaft portion 21 with the small diameter shaft portion 21 fitted in the central opening 10 of the lower half body 11. The nut 29 is screwed into the lower end portion projecting to the end and tightened with the nut to be integrally connected. Further, a cylindrical valve body 31 having a closed upper end which constitutes a variable throttle is rotatably disposed in the hole 23a of the upper half body 12. As shown in FIG. 4, the valve body 31 has an upper half body 1
2 has a through hole 32 that reaches the inner peripheral surface in the radial direction at a position facing the arcuate groove 26 of the large-diameter shaft portion 22, and the small-diameter shaft of the upper half body 12 is formed as shown in FIGS. A communication groove 33 is formed on the outer peripheral surface of the portion 21 corresponding to the space between the through holes 24a and 25a. Further, as shown in FIG. 6, the through hole 24b of the small diameter shaft portion 21 of the upper half body 12 is formed.
And 25b, an elongated hole 34 extending in the axial direction is formed on the outer peripheral surface corresponding to between the inner peripheral surface 25b and the inner peripheral surface 25b.
The positional relationship among the through hole 32, the communication groove 33, and the elongated hole 34 is selected so as to obtain the damping force characteristic with respect to the rotation angle of the valve body 31 shown in FIG. 8, that is, the step angle of step motors 41FL to 41RR described later. ing.

That is, for example, at the position A in FIG. 8 which is the maximum rotation angle position in the clockwise direction, as shown in FIG. 4, only the through hole 32 communicates with the arcuate groove 26, and therefore the piston 8 descends. For pressure side movement, lower pressure chamber 9L
From the pressure side oil flow path 14 to the upper pressure chamber 9U through the orifice formed by the open end of the pressure side oil flow path 14 and the pressure side disk valve 19, and the pressure side flow path C1 shown by a broken line and the lower pressure chamber 9L.
Through the inner peripheral surface of the valve body 31, the through hole 32, the arc-shaped groove 2
6. A pressure side flow path C2, which is shown by a broken line, is formed toward the upper pressure chamber 9U through the orifice formed by the opening end of the pressure side oil flow path 27 and the pressure side disk valve 28, and the piston 8 rises. With respect to the extension side movement, a broken line extending from the upper pressure chamber 9U to the lower pressure chamber 9L through the long groove 16, the extension side flow path 13, and the orifice formed by the opening end and the extension side disk valve 18. Only the extending side flow path T1 shown in the drawing is formed, and a high damping force that rapidly increases as the piston speed increases is generated on the extending side, and a low damping force that slightly increases as the piston speed increases on the pressure side. Generates damping force.

By rotating the valve body 31 counterclockwise from the position A, the communication groove 33 of the valve body 31 and the through holes 24a, 25a of the small diameter shaft portion 21 are communicated with each other, as shown in FIG. Therefore, the opening areas of the communication groove 33 and the through holes 24a and 25a gradually increase as the turning angle increases. Therefore, for the extension side movement of the piston 8, as shown in FIG. 5A, the long groove 16 and the annular groove 15 are arranged in parallel with the flow path T1.
U, the through hole 24a, the communication groove 33, the through hole 25a, the annular groove 15L, the long groove 17, and the lower pressure chamber 9 through the orifice formed by the long groove 17 and the pressure side disk valve 18.
Since the flow path T2 toward L is formed, the maximum value of the damping force gradually increases as the opening area between the communication groove 33 and the through holes 24a and 25a of the small diameter shaft portion 21 increases, as shown in FIG. As shown in FIG. 5 (b), the minimum damping force state is maintained in order to maintain the state in which the flow paths C 1 and C 2 are formed, as shown in FIG. 5B.

Further, when the valve body 31 is rotated counterclockwise to the vicinity of the position B, as shown in FIG. 6, the through holes 24b and 25b of the valve body 31 are communicated by the elongated hole 34. Become. Therefore, for the extension side movement of the piston 8, as shown in FIG. 6A, the elongated groove 16, the annular groove 15U, the through hole 24a, and the elongated hole 3 are arranged in parallel with the flow paths T1 and T2.
4, the flow path T3 that goes toward the lower pressure chamber 9L through the hole 23a
Is formed, and the extension side damping force becomes the minimum damping force state, and with respect to the pressure side movement of the piston 8, in addition to the flow paths C1 and C2, the hole portion 23a, the long hole 34, and the through hole 2 are formed.
4b, a flow path C reaching the long groove 16 through the annular groove 15U
3 and the hole 23a, the long hole 34, the through hole 25b, the annular groove 15L, the through hole 25a, the communication groove 33, the through hole 24a, and the annular groove 15U to form the flow path C4 that reaches the long groove 16. , The minimum damping force state is maintained, as shown in FIG.

Further, when the valve body 31 is rotated in the counterclockwise direction, the opening area between the elongated hole 34 and the through holes 24b and 25b becomes smaller, and the elongated hole 34 and the through hole 24 at the rotation angle θ _B2.
As shown in FIG. 7, the area between b and 25b is blocked, but the opening area between the through hole 32 and the arcuate groove 26 gradually decreases from the rotation angle θ _B2 . Therefore, between the rotation angle θ _B2 and the maximum counter-clockwise rotation angle θ _C , the flow paths T1 and T2 coexist with respect to the extension side movement of the piston 8, so that the minimum damping force state is set. On the contrary, with respect to the pressure side movement of the piston 8, the maximum damping force is gradually increased by gradually decreasing the opening area between the through hole 32 and the arcuate groove 26, and the valve body 31 is positioned. When reaching C, as shown in FIG. 7, the through-hole 32 and the arcuate groove 26 are cut off from each other, so that the lower pressure chamber 9 is prevented from moving toward the pressure side of the piston.
The flow path from L to the upper pressure chamber 9U is only the flow path C1 and is in the compression side high damping force state.

On the other hand, a cylindrical piston rod 35 is fitted in the hole portion 23c of the upper half body 12, and the upper end of the piston rod 35 is projected above the cylinder tube 7 as shown in FIG. , Its upper end side is the vehicle body side member 36
Is fixed to the bracket 37 attached to the bracket 37 by the nut 39 via the rubber bushes 38U and 38L, and the step motors 41FL to 41RR are mounted on the upper end of the piston rod 35 via the bracket 40 so that the rotation shaft 41a of the step motors 41FL to 41RR can be rotated.
Is fixed in a downwardly projecting relationship, and the rotary shaft 41a and the valve body 31 described above are connected by a connecting rod 42 that is loosely inserted in the piston rod 35. In addition, 43 is a bumper rubber. The lower end of the cylinder tube 7 is connected to a wheel side member (not shown).

The input side of the controller 4 is shown in FIG.
As shown in FIG. 5, the vertical acceleration detection values X _2FL ″ to X that are analog voltages that are positive in the upward direction and negative in the downward direction according to the vertical acceleration provided on the vehicle body side corresponding to each wheel position.
Vertical acceleration sensors 51FL to 51RR as vertical acceleration detecting means for outputting _2RR ″, and inductances according to relative displacement between a vehicle body side member and a wheel side member, which are built into the covers of the damping force variable shock absorbers 3FL to 3RR, for example. Relative displacement detection value X which is analog voltage due to change
_DFL (= X _2FL -X _1FL ) ~ X _DRR (= X _2RR-
Stroke sensors 52FL to 52RR as relative displacement detecting means for outputting X _1RR ) are connected, and step motors 41FL to 41RR for controlling the damping force of each damping force variable shock absorber 3FL to 3RR are connected to the output side. .

The controller 4 includes a microcomputer 56 having at least an input interface circuit 56a, an output interface circuit 56b, an arithmetic processing unit 56c and a storage unit 56d, and a vertical acceleration sensor 51.
Vertical acceleration detection value of FL~51RR X _2FL "~X _2RR" and the A / D converter 57FL~57RR supplied to the input interface circuit 56a is converted into a digital value, the stroke sensor 51FL~51RR relative displacement detected value X Input interface circuit 56a by converting _{DFL to} X _DRR into digital values
A / D converters 58FL to 58RR to be supplied to each step motor 4 output from the output interface circuit 56b.
A step control signal for 1FL to 41RR is input, and this is converted into a step pulse to convert each step motor 41FL.
Motor drive circuits 59FL to 59RR for driving the drive circuits 41 to 41RR.

Here, the arithmetic processing unit 56c of the microcomputer 56 determines whether or not an abnormality has occurred in any of the stroke sensors 52FL to 52RR, and when all of the stroke sensors 52FL to 52RR are normal, an up / down operation is performed. body vertical velocity X _2FL '~X _2RR' a stroke sensor 52FL~52 obtained by integrating the vehicle body vertical acceleration detection value X _2FL "~X _2RR" inputted from the acceleration sensor 51FL~51RR
Relative displacement detection value X between wheels and vehicle body input from RR
_DFL (= X _2FL -X _1FL ) ~ X _DRR (= X _2RR-
The damping force coefficient C for performing the skyhook control is determined based on the relative speeds X _DFL ′ to X _DRR ′ obtained by differentiating X _1RR ), and the targets of the step motors 41FL to 41RR corresponding to the determined damping coefficient C are determined. The step angle θ _T is calculated, the difference value between the target step angle θ _T and the current step angle θ _P is calculated, and the step control amount corresponding to this is output to the motor drive circuits 59FL to 59RR. Stroke sensor 5
When an abnormality occurs in 2j (j = FL, FR, RL, RR), the sky is detected based on only the vertical acceleration detection value X _2j ″ without using the relative displacement detection value X _Dj of the stroke sensor 42j that has become abnormal. The damping coefficient C for performing the skyhook approximation control similar to the hook control is calculated, and the step control amount corresponding to the calculated damping coefficient C is output to the motor drive circuits 59FL to 59RR.
The program necessary for the arithmetic processing is stored in advance, and necessary values and arithmetic results in the arithmetic processing are sequentially stored.

Next, the operation of the above embodiment will be described with reference to FIG. 10 showing an example of the processing procedure of the arithmetic processing unit 56c of the microcomputer 56. That is, the process of FIG. 10 is executed as a timer interrupt process at predetermined time intervals (for example, 10 msec). First, each vertical acceleration detection value X _2i ″ is read in step S1, and then the process proceeds to step S2 to detect each relative displacement detection value. X _Di is read, then the process proceeds to step S3, the vertical acceleration detection value X _2i ″ read in step S1 is integrated by, for example, low-pass filter processing to calculate the vehicle vertical velocity X _2i ′, and these are stored. The relative displacement detection value X _Di read in step S2 is temporarily stored in a predetermined storage area of the device 56d, and the relative displacement detection value X _Di read in step S2 is differentiated by, for example, high-pass filtering to calculate a relative speed X _Di ′. After temporarily storing these in a predetermined storage area of the storage device 56d, the process proceeds to step S5.

In step S5, it is determined whether the relative displacement detection value X _Di read in step S2 is a normal value. In this determination, the relative displacement detection value X _Di is within the allowable range of the preset lower limit value L _S and upper limit value U _S (L _S ≦ X _Di
≦ U _S ), it is determined that the stroke sensor 52i is normal when the relative displacement detection value X _Di is within the allowable range, and when it is outside the allowable range, the stroke sensor 52i is determined. It is judged that an abnormality has occurred due to a disconnection or short circuit.

If the result of the determination in step S5 is that each stroke sensor 52i is normal, step S5 is performed.
6, the damping coefficient C for performing the skyhook control is calculated by performing the calculation of the following formula (1) based on the vehicle body vertical velocity X _2i ′ and the relative velocity X _Di ′ calculated in steps S3 and S4. calculate. C = C _S · X _2i ′ / X _Di ′ (1) where C _S is a preset damper damping coefficient.

Next, in step S7, it is determined whether the damping coefficient C calculated in step S6 is less than or equal to the minimum damping force C _{MIN of the} preset damping force variable shock absorber 3i. When> C _MIN ,
In step S8, it is determined whether or not the vehicle body vertical velocity X _2i ′ is positive. If X _2i ′> 0, the process proceeds to step S9 to extend the damping coefficient C calculated in step S6. As set on the side, the target step angle θ _T is calculated with reference to the region of θ _A to θ _B1 of the control map corresponding to FIG. 8 and then the process proceeds to step S10.

In step S10, the storage device 56d
Current step angle θ stored in _PAnd target step angle
θ_TAnd the deviation is calculated as step control amount S
While updating and storing in a predetermined storage area of the storage device 56d,
The target step angle θ_TThe current step angle θ_PAs
Newly memorize, then move to step S11
Step control stored in a predetermined storage area of the unit 56d
Output the quantity S to the motor drive circuit 59i and then interrupt the timer
The process is terminated and the process returns to the predetermined main program.

Further, the determination result of step S8 is X _2i ′ <
When it is 0, the process proceeds to step S12, and the target is referred to by referring to the region of θ _B2 to θ _C of the control map corresponding to FIG. 8 so that the damping coefficient C calculated in step S6 is set on the pressure side. After calculating the step angle θ _T , the process proceeds to step S10. Further, when the determination result of step S7 is C ≦ C _MIN , the process proceeds to step S13, and the target step angle θ _T is set by referring to the regions of θ _B1 to θ _B2 of the control map corresponding to FIG. After the calculation, the process proceeds to step S10.

On the other hand, if the result of the determination in step S5 is that any of the stroke sensors 42i is abnormal, the process proceeds to step S14 and the following is calculated based on only the vehicle body vertical velocity X _2i 'calculated in step S3. The calculation of the equation (2) is performed to calculate the damping coefficient C for performing the skyhook approximation control, and then the process proceeds to step S8. C = α · X _2i ′ (2) Here, α is a control gain, and is a control gain of the damping force variable shock absorber 3i and the characteristics of a vehicle equipped with the damping force variable shock absorber 3i. The control gain is set to a relatively large value in a vehicle where maneuverability is important, and is set to a relatively small value in a vehicle where ride comfort is emphasized.

In the process of FIG. 10, step S1
~ S4, S6 ~ S13 corresponds to the control means, the step.
The process of step S5 corresponds to the abnormality detecting means, and step S1
The process of 3 corresponds to the control changing means. Therefore,
Now, the stroke sensors 52FL to 52RR are normal.
In this state, when the vehicle is driving straight on a flat road,
Since there is almost no vertical movement of the vehicle body, each vertical acceleration sensor 51
Vertical acceleration detection value X output from FL to 51RR_2FL″ 〜
X _2RR″ Is almost zero.

Therefore, when the process of FIG. 10 is executed, the vehicle body vertical velocity X _2FL 'calculated in step S3.
~ X _2RR ′ also becomes substantially zero, and steps S5 to S
Since the damping coefficient C calculated after shifting to 6 also becomes substantially zero, the _{routine proceeds} from step S7 to step S13, and the step angles θ _{B1 to} θ _B2 of the expansion-side and _compression- side minimum damping coefficients C _nMIN and C _aMIN are set. The step angle within the range is the target step angle θ
_It is set as _T , and the step motors 41FL to 41RR are driven so that the step angles thereof match the target step angle θ _T. Therefore, the damping force variable shock absorber 3FL
The valve element 31 of 3RR is set to the position B shown in FIG. 6, and the damping coefficients C on the extension side and the compression side of the piston 8 are set to the minimum damping coefficients C _nMIN and C _aMIN , respectively. Therefore, in this state, even if vibrations due to fine unevenness of the road surface are input to the wheels, the vibrations are absorbed by the damping force variable shock absorbers 3FL to 3RR and are not transmitted to the vehicle body, and a good ride comfort can be secured. .

In this running condition on a good road, for example, a step up to the front
When passing a temporary step such as a difference, pass this step
If the vehicle body does not move up and down due to
_2FL’～ X_2RRSince ′ maintains zero, the minimum damping coefficient C
_aMINAnd C_nMINTo maintain the condition, the wheels should ride on the step
It can absorb the pushing force when raised, but
Riding on a relatively large step and absorbing the thrust force
If you can not move it, the vehicle body will also be displaced upward.
Therefore, the vertical speed X of the vehicle body_2FL’～ X_2RR′ Is the positive direction
Will increase. Thus, the vehicle body vertical velocity X
_2FL’～ X_2RRIf ′ increases in the positive direction, step S7
To step angle θ in FIG._A~ Θ_B1Decay in the region of
Target step angle θ according to coefficient C_TIs calculated,
Variable damping force shock absorber 3FL-3RR valve body 31
Switching control is performed as shown in FIG. As a result, step riding
Relative speed X by raising_DFL’～ X_DRR′ Is negative
Displacement speed X_2iDisplacement speed X on the wheel side with respect to_1i'But
When the piston 8 moves to the pressure side at high speed,
Small damping coefficient C_aMINVibrations to the wheel side
It can absorb the input, and over this step
As a result, the ascending speed on the wheel side is higher than the ascending speed on the vehicle body side.
When it gets smaller, the relative speed X_DFL’～ X_DRR′ Becomes positive
As a result, the piston 8 moves to the extension side. At this time
Suppresses the rise of the vehicle body because the damping coefficient C has a large value.
Demonstrate the damping effect, and then the car body stops rising
And the vertical speed X of the vehicle body_2FL’～ X_2RR′ Becomes zero
Therefore, as described above, the step motors 41FL to 41RR are
It is rotated counterclockwise and returned to position B.
The minimum damping coefficient C on both the compression and extension sides_aMINAnd C_nMINTo
Controlled and then the car body begins to descend
Vertical speed X_2FL’～ X _2RR′ Increases in the negative direction
As a result, the process moves from step S8 to step S12.
Then, referring to the control map of FIG._B2~ Θ_C
Target step angle θ according to the damping coefficient C in the range of_TCalculate
The valve body 31 is rotated further counterclockwise.
And is rotated to the rotation position shown in FIG. Because of this, the car
Body descends and relative velocity X_DFL’～ X_DRR′ Is negative
Therefore, the damping force is large when the piston 8 moves to the pressure side.
As it becomes louder, a great damping effect is exerted.

On the contrary, when the wheels pass through the step on the front lower side, the wheels rebound first to increase the relative speeds X _DFL ′ to X _DRR ′ in the positive direction, but at this time, the vehicle body does not move up and down. Vertical speed of the vehicle X _2FL '~ X
_{Since 2RR} 'is zero, the damping coefficients of the variable damping force shock absorbers 3FL to 3RR are the minimum damping coefficients C _aMIN and C _{nM IN.}
Then, when the vehicle body starts to descend after that, when the vehicle body vertical speeds X _2FL ′ to X _2RR ′ increase in the negative direction, the damping coefficient C becomes a large value and the step angle θ _Since the target step angle θ _{T in} the range of _{B2 to} θ _C is calculated and the valve body 31 is rotated to the position shown in FIG. 7, a large damping force is applied to the movement of the piston 8 on the pressure side. A large damping effect can be exerted by giving the same, and thereafter, the valve body 31 is rotated clockwise in accordance with the decrease in the vehicle body vertical speeds X _2FL ′ to X _2RR ′ and the decrease in the damping coefficient C. Return to the B side, and the vehicle body vertical speed X _2FL ′ ~
When X _2RR ′ becomes zero, the valve body 31 becomes the position B, and the minimum damping coefficients C _aMIN and C _nMIN are obtained. After that, when the vehicle body starts to rise by _swinging back, the vehicle body vertical velocities X _2FL ′ to X _2RR ′ increase in the positive direction and the relative velocities X _DFL ′ to X _DRR ′ become the positive direction, so that the damping coefficient C As the target step angle θ _T on the side of the step angle θ _A is calculated with an increase in the valve angle, the valve body 31 is rotated clockwise to the position shown in FIG. It is possible to exert a large damping force on the vibration damping effect.

As described above, when passing a temporary step while traveling on a good road, a good damping effect can be exhibited by skyhook control, and when traveling on a bad road. Also, the target step angle θ _T on the step angle θ _A side (or step angle θ _C side) is calculated by the positive (or negative) of the vehicle body vertical velocities X _2FL ′ to X _2RR ′, so that the vehicle body rises. When the relative speeds X _DFL ′ to X _DRR ′ are negative and the vehicle body is descending so that the relative speeds X _DFL ′ to X _DRR ′ are positive, the damping coefficient C is the minimum damping coefficient C.
_By controlling to _aMIN and _CnMIN , conversely, the vehicle body rises and the relative velocity X _DFL ′ to X _DRR ′ is positive, and the vehicle body descends and the relative velocity X.
When the damping direction is such that _DFL ′ to X _DRR ′ are negative, the damping coefficient C is set to the vertical velocity X _2FL ′ to X _2RR ′ and the relative velocity X.
Controlling to the optimum damping coefficient according to _DFL '~ X _DRR ',
A good ride comfort can be secured.

Even when the vehicle is traveling on a rough road, the vehicle body is raised and the relative speeds X _DFL ′ to X X are reached as in the case of passing the step.
_{When DRR} 'is negative and the car body is descending, the relative speed X _DFL ' ~ X
_The damping coefficient C is controlled to the minimum damping coefficients C _aMIN and C _nMIN when _DRR ′ is in the positive excitation direction, and conversely, the vehicle body rises and the relative speeds X _DFL ′ to X _DRR ′ are positive and the vehicle body is The damping coefficient C is _{adjusted according} to the vertical speeds X _2FL ′ to X _2RR ′ and the relative speeds X _DFL ′ to X _DRR ′ in the damping direction in which the relative speeds X _DFL ′ to X _DRR ′ become negative and become negative. It is possible to secure a good riding comfort by controlling the damping coefficient to the optimum value.

In this skyhook control state, any one of the stroke sensors 52FL to 52RR 52j (j = FL, F).
R, RL, RR) Relative displacement detection value X due to disconnection or short circuit
_{When Di} is out of the setting range, step S5 to step S5
Since the process shifts to 14, the control mode is changed from the skyhook control based on the vehicle body vertical velocity X _2i ′ and the relative velocity X _Di ′ to the skyhook approximate control based only on the vehicle body vertical velocity X _2i .

In this skyhook approximation control,
Speed X_2iWhen ′ is positive, that is, when the vehicle body is in the ascending direction,
Is a step based on the damping coefficient C calculated by the equation (2).
Angle θ _ASide target step angle θ_TCalculate the vertical speed of the vehicle body
Degree X_2iWhen ′ is negative, that is, when the vehicle body is descending,
Step angle θ based on the calculated damping coefficient C_CSide goal
Step angle θ_TTherefore, the valve body 31 is turned off.
The replacement area is the same as in the case of the skyhook control described above.
And the damping coefficient C is the vertical velocity X of the vehicle body. _2i'And
And relative speed X_DiOn the body instead of being calculated based on
Lower speed X_2iSwitching based on the difference in the points calculated based only on
The position is only slightly displaced, and the damping force variable shock
The minimum damping force control on the compression side or extension side of the absorber 3i is a valve.
The pressure side and extension side flow paths differ depending on the switching position of the body 31.
It is automatically done by the sky hook control.
There is no change and the ride quality is slightly reduced, but the control mode is
The same control can be continued, and
It has a great impact on driving stability and riding comfort
Can be reliably avoided.

In the above embodiment, the case where the damping force variable shock absorber is applied as the suspension device has been described, but the present invention is not limited to this, and an air spring whose spring constant can be changed may be applied. it can. Further, in the above-described embodiment, the case where the valve body 31 for controlling the damping force is configured to be a rotary type has been described, but the present invention is not limited to this, and it is configured to be a spool type, and the compression side and the extension side are configured. Different flow paths may be formed. In this case, a pinion is connected to the rotary shaft 41a of the step motors 41FL to 41RR, and a rack that meshes with the pinion is attached to the connecting rod 42 or an electromagnetic solenoid is applied. The sliding position of the valve body 31 may be controlled by the above.

Further, in the above embodiment, from the road surface
For suppressing the change in the posture of the vehicle body due to the vibration input of
However, not limited to this, the turning state and braking state of the vehicle
Etc. to detect changes in the vehicle's posture and
Suppressing control may be performed together. Even more
Further, in the above embodiment, the microcomputer 56
The explanation was given for the case of applying and controlling.
As shown in Fig. 11, vertical acceleration is not fixed.
The output of the degree sensor 51i by the integrator 61
Speed X _2i′ And the stroke sensor 52i
The output of is differentiated by the differentiation circuit 62 and the relative velocity X_Di′ Is calculated
The stroke sensor 52i output within the allowable range.
Upper limit value U_SAnd lower limit L_SAnomaly detection hand with
Allowed by supplying to the window comparator 63 as a stage
When it is out of the range, for example, an abnormality detection signal of logical value "1"
And the vertical speed X of the vehicle body_2i′ And relative speed
X_Di′ Is input to the arithmetic circuit 64 for performing the arithmetic operation of the equation (1).
And the vertical speed X of the vehicle body_2i′ Is calculated by the equation (2)
Input to the arithmetic circuit 65 for calculating the damping coefficient C respectively
Then, the calculated attenuation coefficient C is set to the logical value of the abnormality detection signal.
When it is “0”, the output of the arithmetic circuit 64 is selected, and the logic
Select to select the output of the arithmetic circuit 65 when the value is "1".
The selection output of the selection circuit 66 is supplied to the selection circuit 66.
Supplied to the motor drive circuit 67 and attenuated according to the attenuation coefficient C.
Calculate the step control amount that generates force and respond to it
Output step pulse to step motor 41i
Control the damping force of the variable damping force shock absorber 3.
You may control.

Furthermore, in the above embodiment, the case where the skyhook approximation control is performed when an abnormality occurs in the stroke sensor 52i has been described, but the present invention is not limited to this, and the vehicle body vertical speed X _{2i is} simply used. It is also possible to determine whether or not ′ is a predetermined value abnormality and control the damping force in two stages of high and low. Further, in the above embodiment, the case where the potentiometer is applied as the stroke sensor has been described, but the present invention is not limited to this, and an ultrasonic distance sensor that detects the relative distance between the vehicle body and the road surface, and a detection coil are used. Any relative displacement detecting means such as a displacement sensor that detects displacement by impedance change or inductance change can be applied.

Further, in the above embodiment, the vertical acceleration sensors 51FL to 51FL are located at the respective wheels 1FL to 1RR of the vehicle body 2.
Although the case where RR is provided has been described, any one vertical acceleration sensor may be omitted and the vertical acceleration at the omitted position may be estimated from the values of other vertical acceleration sensors. Furthermore, in the above embodiment, the case where the step motors 41FL to 41RR are subjected to open loop control has been described, but the present invention is not limited to this, and the closed angle control is performed by detecting the rotation angle of the step motor with an encoder or the like and feeding it back. You may do it.

[0039]

As described above, according to the suspension control device of the present invention, the damping force variable shock is determined based on the relative displacement detection value of the relative displacement detection means and the vehicle body vertical acceleration detection value of the vertical acceleration detection means. In a suspension control device for controlling suspension characteristics of a suspension device such as an absorber, when an abnormal state of the relative displacement detecting means is detected by the abnormal state detecting means, the control changing means uses only the vertical acceleration detection value. Since the configuration is changed to control the suspension characteristic, the suspension characteristic control can be continued only based on the vertical acceleration detection value when an abnormality occurs in the relative displacement detection means. Suspension characteristics control such as suspension of suspension characteristics control Change effect is obtained that it is possible to reliably prevent the greatly affects the steering stability and riding comfort.

[Brief description of drawings]

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

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

FIG. 3 is a front view with a part in section showing an example of a damping force variable shock absorber.

FIG. 4 is an enlarged cross-sectional view showing a damping force adjusting mechanism in a maximum damping force state when the vehicle body is raised.

FIG. 5 is an enlarged cross-sectional view showing a damping force adjusting mechanism in an intermediate damping force state when the vehicle body is elevated, (a) showing an extension side and (b) showing a pressure side hydraulic fluid path, respectively.

FIG. 6 is an enlarged cross-sectional view showing a damping force adjusting mechanism when there is no change in the vehicle body, in which (a) shows a hydraulic fluid path on the extension side and (b) shows a hydraulic fluid path on the pressure side.

FIG. 7 is an enlarged sectional view showing a damping force adjusting mechanism in a maximum damping force state when the vehicle body is descending, (a) showing an extension side and (b) showing a pressure side hydraulic fluid path, respectively.

FIG. 8 is an explanatory diagram showing damping force characteristics with respect to a step angle of a damping force variable shock absorber.

FIG. 9 is a block diagram showing an example of a controller.

FIG. 10 is a flowchart illustrating an example of a processing procedure of a controller.

FIG. 11 is a block diagram showing another example of the controller.

[Explanation of symbols]

 1FL to 1RR Wheels 2 Vehicles 3FL to 3RR Damping force variable shock absorber 4 Controller 8 Piston 11 Lower half 12 Upper half 13 Expansion side oil flow path 14 Pressure side oil flow path 18 Expansion side disk valve 19 Pressure side disk valve 28 Pressure side disk valve 31 valve body 32 through hole 33 communication groove 34 long hole 35 piston rod T1 to T3 extension side flow path C1 to C4 pressure side flow path 41FL to 41RR step motor 51FL to 51RR vertical acceleration sensor 52FL to 52RR stroke sensor 56 microcomputer 59FL to 59RR Motor drive circuit 61 Integrator 62 Differentiation circuit 63 Window comparator (abnormality detection means) 64, 65 Arithmetic circuit 65 Selection circuit 66 Motor drive circuit

Claims (1)

[Claims] 1. A suspension device capable of changing a vehicle body posture change suppressing characteristic according to an input control signal interposed between a vehicle body side member and a wheel side member, and a suspension device at a position of the suspension device of the vehicle body. Vertical acceleration detecting means for detecting vertical acceleration, relative displacement detecting means for detecting relative displacement between the vehicle body side member and wheel side member, vertical acceleration detection value of the vertical acceleration detecting means and relative displacement of the relative displacement detecting means. A suspension control device comprising: a control unit that forms and outputs the control signal that suppresses a change in the attitude of the vehicle body based on a detected value; an abnormality detection unit that detects an abnormal state of the relative displacement detection unit; When an abnormality is detected by the abnormality detecting means, the control mode by the control means is changed to form a control signal based only on the vertical acceleration detection value. A suspension control device comprising: a control changing unit.