JP3087501B2 - Suspension control device - Google Patents

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 control characteristics of a suspension are controlled based on a displacement speed of a vehicle body and a relative speed between the vehicle body and wheels.

[0002]

2. Description of the Related Art A conventional suspension control device is disclosed in, for example, Japanese Patent Application Laid-Open No. 61-360 proposed by the present applicant.
No. 13 is disclosed. This conventional example uses a variable damping force shock absorber that can switch the damping force into three stages of high, medium, and low by a driving motor, and drives the driving motor such as a vehicle height detector, a road surface detector, and the like. And control based on the detection signal of the road surface state detecting means to suppress a change in the posture of the vehicle body. When a system abnormality occurs due to abnormality of various sensors or abnormality of the control system, the damping force variable shock is controlled. The damping force control is stopped by controlling the absorber to the intermediate damping force and turning on the abnormality warning lamp.

[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, for example, when traveling on a rough road, when the posture change of the vehicle body is large, or when traveling on a gravel road, etc. When 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 and the steering stability decreases, and the riding comfort also deteriorates.

Accordingly, the present invention has been made in view of the above-mentioned unsolved problems of the prior art, and is provided for controlling when a relative displacement detecting means for detecting a relative displacement between a vehicle body and a wheel has an abnormality. 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 provided between a vehicle body-side member and a wheel-side member as shown in a basic configuration diagram of FIG. A suspension device capable of changing a vehicle body posture change suppression characteristic in response to an input control signal, a vertical acceleration detecting means for detecting a vertical acceleration of the vehicle body at the position of the suspension device, a vehicle body side member and a wheel side A relative displacement detecting means for detecting a relative displacement between members, and the control signal for suppressing a change in posture of the vehicle body based on a vertical acceleration detection value of the vertical acceleration detecting means and a relative displacement detection value of the relative displacement detecting means. A suspension control device comprising: a control unit that outputs an output of the relative displacement; an abnormality detection unit that detects an abnormal state of the relative displacement 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 controls the suspension device by forming a control signal based on the vertical acceleration detecting value and the relative displacement detecting value. By performing, for example, skyhook control to suppress a change in the attitude of the vehicle body and block vibration input from the road surface, when an abnormality occurs in the relative displacement detection means, control is performed based only on the vertical acceleration detection value. By shaping the signal,
The skyhook approximation control is performed to continue the vehicle body posture change suppression control.

[0007]

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

[0008] Variable damping force shock absorber 3FL-3RR
Is a twin-tube gas-filled strut type having a cylinder tube 7 composed of an outer cylinder 5 and an inner cylinder 6 as shown in FIGS. 8 define upper and lower pressure chambers 9U and 9L. 4 to 7, the piston 8 has a cylindrical lower half 11 having a sealing member 9 molded on the outer peripheral surface thereof in sliding contact with the inner cylinder 6 and having a center opening 10 on the inner peripheral surface. The lower half 11 has an upper half 12 fitted therein.

The lower half body 11 has an extending oil passage 13 penetrating vertically and a sealing member 9 extending downward from the upper surface.
The hole 14 a having a diameter larger than that of the extension-side oil flow path 13 and extending from the outer peripheral surface of the cylindrical body 11 to the hole 14.
a, a pressure-side oil flow path 14 formed of a hole 14b drilled in communication with the bottom of the hole a, annular grooves 15U, 15L formed at the upper and lower open ends of the central hole 10, and formed on the upper surface side. A long groove 16 communicating with the annular groove 15U and the expansion-side oil flow path 13 and a long groove 17 formed on the lower surface side and communicating with the annular groove 15L are formed. The long groove 17 is closed by the extension-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 inserted into the center opening 10 of the lower half body 11 and the shaft portion 2.
The lower end face of the small-diameter shaft portion 21 is formed at the center of the small-diameter shaft portion 21 and the large-diameter shaft portion 22. 23a extending from the side to the middle of the large-diameter shaft portion 22, and a hole 23b communicating with the upper end of the hole 23a and having a smaller diameter than the hole 23a.
And a hole 23c having a larger diameter than the hole 23c communicating with the upper end side of the hole 23b. The through hole 23 is formed at a position facing the annular grooves 15U and 15L of the small diameter shaft 21 respectively. Pair of through holes 24 penetrating the inner peripheral surface side in the direction
a, 24b and 25a, 25b are drilled, and the upper end side of the hole 23a of the large-diameter shaft portion 22 is connected to the arc-shaped groove 2 communicating therewith.
6 is formed, and an L-shaped pressure-side oil flow path 27 communicating with the arc-shaped groove 26 and the lower end face is formed.
Is blocked by

The lower half 11 and the upper half 12 are positioned below the lower half 11 of the small-diameter shaft 21 with the small-diameter shaft 21 inserted into the center opening 10 of the lower half 11. The nut 29 is screwed into the lower end protruding from the nut, and the nut 29 is tightened to be integrally connected. Further, a cylindrical valve body 31 whose upper end is closed in a hole 23a of the upper half body 12 and constitutes a variable throttle is rotatably disposed. As shown in FIG. 4, the upper half 1
2, a through-hole 32 is formed at a position facing the arc-shaped groove 26 of the large-diameter shaft portion 22 so as to reach the inner peripheral surface in the radial direction, and the small-diameter shaft of the upper half body 12 as shown in FIGS. A communication groove 33 is formed in the outer peripheral surface corresponding to the space between the through holes 24a and 25a of the portion 21, and 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.
An elongated hole 34 extending in the axial direction is formed in the outer peripheral surface corresponding to the area between the inner peripheral surface and the inner peripheral surface side.
Then, the positional relationship between the through hole 32, the communication groove 33, and the long 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 angles of the 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 arc-shaped groove 26, so that the piston 8 descends. For pressure side movement, lower pressure chamber 9L
A pressure-side flow path C1 (shown by a dashed line) passing through the orifice formed by the open end of the pressure-side oil flow path 14 and the pressure-side disc valve 19 toward the upper pressure chamber 9U, and a lower pressure chamber 9L.
Through the inner peripheral surface of the valve body 31, through hole 32, arc-shaped groove 2
6. A pressure-side flow path C2, shown by a broken line, which passes through the pressure-side oil flow path 27, passes through an orifice formed by the opening end thereof and the pressure-side disc valve 28, and goes to the upper pressure chamber 9U, and the piston 8 rises. For the extension side movement, the upper pressure chamber 9U passes through the long groove 16 and the extension side flow path 13 and passes through the orifice formed by the opening end and the extension side disc valve 18 to the broken line toward the lower pressure chamber 9L. Only the expansion side flow path T1 shown in the figure is formed, and a high damping force is generated on the expansion side, which rapidly increases in accordance with an increase in the piston speed, and a low damping force on the compression side is slightly increased in accordance with the increase in the piston speed. Generates damping force.

By rotating the valve body 31 in the counterclockwise direction 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 communicate with each other as shown in FIG. The opening area between the communication groove 33 and the through holes 24a and 25a gradually increases as the rotation angle increases. For this reason, as shown in FIG. 5 (a), when the piston 8 moves on the extension side, 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 disc valve 18.
A flow path T2 toward L is formed, and 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. 5B, for the movement on the extension side, the state where the flow paths C1 and C2 are formed is maintained, so that the minimum damping force state is maintained.

Further, when the valve element 31 is rotated counterclockwise to be in the vicinity of the position B, as shown in FIG. 6, a state is established in which the through hole 24b, 25b of the valve element 31 is communicated by the elongated hole 34. Become. For this reason, as shown in FIG. 6A, the elongated groove 16, the annular groove 15U, the through hole 24a, the elongated hole 3 are arranged in parallel with the flow paths T1 and T2 with respect to the extension side movement of the piston 8.
4. Flow path T3 passing through hole 23a toward lower pressure chamber 9L
Is formed, the extension-side damping force becomes the minimum damping force state, and the piston 23 moves against the compression side in addition to the flow passages C1 and C2 as well as the hole 23a, the long hole 34, and the through hole 2
4b, the flow path C reaching the long groove 16 through the annular groove 15U
3, a flow path C4 is formed that reaches the long groove 16 through 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. As shown in FIG. 8, the minimum damping force state is maintained.

Further, when the valve element 31 is rotated in the counterclockwise direction, the opening area between the elongated hole 34 and the through holes 24b and 25b is reduced, and the elongated hole 34 and the through hole 24 are rotated at the rotation angle θ _B2.
7, the opening area between the through hole 32 and the arc-shaped groove 26 gradually decreases from the rotation angle θ _B2 . For this reason, between the rotation angle θ _B2 and the maximum rotation angle θ _{C in the} counterclockwise direction, the flow path T1 and T2 coexist for the movement of the piston 8 on the extension side, so that the minimum damping force state is set. On the contrary, when the piston 8 is moved on the pressure side, the opening area between the through hole 32 and the arc-shaped groove 26 is gradually reduced, so that the maximum damping force is gradually increased, and the valve body 31 is moved to the position. As shown in FIG. 7, when the piston reaches pressure C, the space between the through-hole 32 and the arc-shaped groove 26 is cut off.
The flow path from L to the upper pressure chamber 9U is only the flow path C1, and the pressure side is in a high damping force state.

On the other hand, a cylindrical piston rod 35 is fitted into the hole 23c of the upper half body 12, and the upper end of the piston rod 35 projects upward from the cylinder tube 7, as shown in FIG. The upper end side is the vehicle body side member 36.
Is fixed by a nut 39 via rubber bushes 38U and 38L to a bracket 37 attached to the piston rod 35, and the step motors 41FL to 41RR are mounted on the upper end of the piston rod 35 via a bracket 40 by the rotation shaft 41a.
The rotating shaft 41a and the above-described valve element 31 are connected by a connecting rod 42 loosely inserted into the piston rod 35. 43 is a bumper rubber. The lower end of the cylinder tube 7 is connected to a wheel-side member (not shown).

The controller 4 has, on its input side,
As shown in the figure, according to the vertical acceleration provided on the vehicle body side corresponding to each wheel position, the vertical acceleration detection values X _2FL ″ to X composed of analog voltages that are upwardly positive and downwardly negative are provided.
Vertical acceleration sensors 51FL to 51RR as vertical acceleration detecting means for outputting _2RR ", and inductances which are incorporated in covers of, for example, variable damping force shock absorbers 3FL to 3RR and correspond to relative displacement between the vehicle body side member and the wheel side member. Relative displacement detection value X consisting of analog voltage due to change
_DFL (= X _2FL −X _1FL ) to X _DRR (= X _2RR −
X _1RR) and the stroke sensor 52FL~52RR as relative displacement detecting means for outputting are connected to step motor 41FL~41RR to control the damping force of each damping force variable shock absorber 3FL~3RR the output side is connected .

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;
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 converts the _DFL to X _DRR to a digital value
A / D converters 58FL to 58RR to be supplied to each of the step motors 4 output from the output interface circuit 56b.
Step control signals for 1FL to 41RR are input, and are converted into step pulses to convert each step motor 41FL.
And a motor drive circuit 59FL to 59RR for driving .about.41RR.

Here, the arithmetic processing unit 56c of the microcomputer 56 determines whether or not any of the stroke sensors 52FL to 52RR has an abnormality. 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 wheel and vehicle input from RR
_DFL (= X _2FL −X _1FL ) to X _DRR (= X _2RR −
X _1RR ), the damping force coefficient C for performing the skyhook control is determined based on the relative speeds X _DFL ′ to X _DRR ′, and the target of the step motors 41 FL to 41 RR corresponding to the determined damping coefficient C. A step angle θ _T is calculated, a difference value between the target step angle θ _T and the current step angle θ _P is calculated, and a corresponding step control amount 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 abnormal stroke sensor 42 _j. A damping coefficient C for performing skyhook approximation control similar to hook control is calculated, and a step control amount corresponding thereto is output to the motor drive circuits 59FL to 59RR.
The program necessary for the arithmetic processing is stored in advance, and the necessary values and the arithmetic result 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 performed as the predetermined time (e.g., 10 msec) timer interrupt processing for each, first reads the vertical acceleration detection value X _2i "in step S1, then the processing proceeds to step S2 each relative displacement detected value _XDi is read, and then the process proceeds to step S3 to calculate the vehicle body vertical speed _X2i 'by integrating the vertical acceleration detection value _X2i "read in step S1 by, for example, performing a low-pass filter process, and storing these. The relative speed X _Di ′ is temporarily stored in a predetermined storage area of the device 56d, and then the process proceeds to step S4 to differentiate the relative displacement detection value X _Di read in step S2 by, for example, high-pass filter processing, These are temporarily stored in a predetermined storage area of the storage device 56d, and then the process proceeds to step S5.

In step S5, it is determined whether or not the relative displacement detection value X _Di read in step S2 is a normal value. This determination is made so that 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 ). When the relative displacement detection value X _Di is within the allowable range, the stroke sensor 52i is determined to be normal. When the relative displacement detection value X _Di is outside the allowable range, the stroke sensor 52i is determined. It is determined that an abnormality has occurred due to disconnection or short circuit.

If it is determined in step S5 that each stroke sensor 52i is normal, step S5 is executed.
6, the damping coefficient C for performing the skyhook control is calculated by performing the following equation (1) based on the vehicle body vertical speed X _2i ′ and the relative speed 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, the process proceeds to step S7, where it is determined whether the damping coefficient C calculated in step S6 is equal to or less than a predetermined minimum damping force C _MIN of the variable damping force shock absorber 3i. When> C _MIN ,
The process proceeds to step S8 to determine whether the vehicle body vertical speed X _2i ′ is positive. If X _2i ′> 0, the process proceeds to step S9 to extend the damping coefficient C calculated in step S6. to set the side, the transition from calculates the target step angle theta _T with reference to the region of the theta _a through? _B1 of the control map corresponding to Figure 8 to step S10.

In step S10, the storage device 56d
Current step angle θ stored in _PAnd target step angle
θ_TIs calculated as a step control amount S.
While updating and storing in a predetermined storage area of the storage device 56d,
The target step angle θ_TIs the current step angle θ_PUpdate as
New storage is performed, and then the process proceeds to step S11,
Step control stored in a predetermined storage area of the storage 56d
Outputs the amount S to the motor drive circuit 59i and then interrupts the timer
The process ends and returns to the predetermined main program.

The result of the determination in step S8 is X _2i '<
If it is 0, the process proceeds to step S12, and the target value is set with reference to the range 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 determined by referring to the region 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 one of the stroke sensors 42i is abnormal, the process proceeds to step S14, and based on only the vehicle body vertical speed X _2i 'calculated in step S3, After calculating the equation (2) to calculate the damping coefficient C for performing the skyhook approximation control, the process proceeds to step S8. C = α · X _2i ′ (2) Here, α is a control gain, and is a control gain of the variable damping force shock absorber 3i and a characteristic of a vehicle equipped with the variable damping force shock absorber 3i. The control gain is set to a relatively large value for a vehicle that emphasizes maneuverability, and the control gain is set to a relatively small value for a vehicle that emphasizes riding comfort.

In the process of FIG. 10, step S1
Steps S4 to S13 correspond to the control means.
The processing in step S5 corresponds to the abnormality detection means, and the processing in step S1
The process of No. 3 corresponds to the control change means. Therefore,
Now, it is assumed that the stroke sensors 52FL to 52RR are normal.
When the vehicle is traveling straight on a flat good 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 substantially zero.

Therefore, when the processing of FIG. 10 is executed, the vehicle body vertical speed X _2FL 'calculated in step S3.
~ X _2RR ′ is also substantially zero, and steps S5 to S2
6, the damping coefficient C calculated also becomes substantially zero, so the _flow shifts from step S7 to step S13, where the step angles θ _{B1 to} θ _{B2 at which} the expansion-side and _compression- side minimum damping coefficients C _nMIN and _{Ca MIN} are obtained. Set the step angle within the range to the target step angle θ
Set as _T, step angle of the stepping motor 41FL~41RR is driven to match the target step angle theta _T. For this reason, variable damping force shock absorber 3FL
6 are set to the position B shown in FIG. 6, whereby the extension side and _compression side damping coefficients C of the piston 8 are set to the minimum damping coefficients _CnMIN and _CaMIN , respectively. Therefore, in this state, even if vibrations due to fine irregularities on the road surface are input to the wheels, the vibrations are absorbed by the variable damping force shock absorbers 3FL to 3RR and are not transmitted to the vehicle body, so that a good ride comfort can be secured. .

In this good road running state, for example,
When passing through a temporary step such as a difference,
When the vehicle does not move up and down due to
_2FL'~ X_2RR′ Remain zero, so that the minimum damping coefficient C
_aMINAnd C_nMINWheels ride on steps to maintain condition
Although it can absorb the pushing force when raised,
Riding on a relatively large step, absorbing the thrust
Otherwise, the vehicle will be displaced upward.
Therefore, the vehicle vertical speed X_2FL'~ X_2RR′ Is positive
Will increase. Thus, the vehicle vertical speed X
_2FL'~ X_2RR′ Increases in the positive direction, step S7
And the step angle θ in FIG._A~ Θ_B1Attenuation in the area
Target step angle θ according to coefficient C_TIs calculated, so
The damping force variable 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, ie the body
Side displacement speed X_2i′ To the wheel side displacement speed X_1i'But
When the piston 8 moves to the compression side at high speed, the compression
Small damping coefficient C_aMINVibration to the wheel side
Input can be absorbed, and from this state the step
As a result, the rising speed on the wheel side is
Relative speed X_DFL'~ X_DRR′ Is positive
As a result, the piston 8 moves to the extension side. At this time
Means that the damping coefficient C has a large value,
Demonstrate the damping effect, then stop the lift of the body
And body vertical speed X_2FL'~ X_2RR′ Becomes zero
As described above, the step motors 41FL to 41RR are
It is rotated counterclockwise to return to position B, thereby
The minimum damping coefficient C on both the compression side and the extension side_aMINAnd C_nMINTo
Control, and then when the vehicle begins to descend,
Body speed X_2FL'~ X _2RR′ Increases in the negative direction
As a result, the process moves from step S8 to step S12.
And the step angle θ with reference to the control map of FIG._B2~ Θ_C
Target step angle θ according to the damping coefficient C in the range of_TCalculate
As a result, the valve element 31 is further rotated counterclockwise.
Then, it is turned to the turning position shown in FIG. Because of this, the car
Body descends and relative speed X_DFL'~ X_DRR′ Is negative
When the piston 8 moves to the compression side, the damping force is large.
Greater vibration exerts a great damping effect.

Conversely, when the wheels pass through the step of descending forward, the relative speeds X _DFL 'to X _DRR ' increase in the forward direction due to the rebound of the wheels. However, at this time, the vehicle body does not move up and down. Body vertical speed X _2FL '~ X
_{Since 2RR} 'is zero, the damping coefficients of the damping force variable shock absorbers 3FL to 3RR are the minimum damping coefficients C _aMIN and C _{nM IN}
Maintaining, allowing the lowering of the wheels, then the vehicle starts to descend, the vehicle body vertical velocity X _2FL '~X _2RR' is increased in the negative direction, is the attenuation coefficient C is a large value, the step angle θ will _{be B2} through? _C target step angle theta _T ranging is calculated, since the valve body 31 is rotated to the position shown in FIG. 7, a large damping force against movement of the compression side of the piston 8 As a result, the valve body 31 is rotated clockwise as the vehicle vertical speeds X _2FL ′ to X _2RR ′ become smaller and the damping coefficient C becomes smaller. Return to the B side, and the vehicle vertical speed _X2FL '~
When X _2RR ′ becomes zero, the valve element 31 is at the position B, and has the minimum damping coefficients C _aMIN and C _nMIN . Thereafter, when the vehicle body starts rising by _swinging back, the vehicle body vertical speeds X _2FL ′ to X _2RR ′ increase in the positive direction, and the relative speeds X _DFL ′ to X _DRR ′ become the positive direction. is the target step angle theta _T as a step angle theta _a side with an increase in the calculation, by the valve body 31 is a position shown in FIG. 5 is rotated in the clockwise direction, the movement of the extension side of the piston 8 , A large damping force can be given to exert a vibration damping effect.

As described above, when the vehicle travels on a temporary step while traveling on a good road, a good vibration damping effect can be exerted by the skyhook control. also, by the target step angle theta _T positive vehicle body vertical velocity X _2FL '~X _2RR' (or negative) by the step angle theta _a side (or step angle theta _C side) is calculated, the vehicle body is raised When the relative speeds X _DFL 'to X _DRR ' are negative and the vehicle body descends and the relative speeds X _DFL 'to X _DRR ' are positive, the damping coefficient C is set to the minimum damping coefficient C.
_aMIN and _CnMIN , the vehicle body rises and the relative speeds X _DFL 'to X _DRR ' become positive, and the vehicle body descends and the relative speed X
_DFL 'to X _DRR' vertical velocity of the damping coefficient C when it is damping direction as the negative X _2FL 'to X _2RR' and relative velocity X
_By controlling to the optimal damping coefficient according to _DFL 'to _XDRR ',
Good ride comfort can be ensured.

Also, even when the vehicle is traveling on a rough road, the vehicle body rises and the relative speeds X _DFL 'to X
_DRR 'is negative and the body descends and the relative speed X _DFL ' ~ X
_{When DRR} 'is in the excitation direction where it is positive, the damping coefficient C is controlled to the minimum damping coefficients C _aMIN and C _nMIN , and conversely, the vehicle body rises and the relative speeds X _DFL ' to X _DRR 'become positive and the vehicle body becomes When the relative velocity X _DFL 'to X _DRR ' is lowered and the relative velocity X _DFL 'to X _DRR ' is negative, the damping coefficient C is _{adjusted according} to the vertical velocity X _2FL 'to X _2RR ' and the relative velocity X _DFL 'to X _DRR '. By controlling to an optimal damping coefficient, a good ride comfort can be secured.

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

In this skyhook approximation control,
Speed X_2i'Is positive, that is, when the vehicle
Is a step based on the attenuation coefficient C calculated by the above equation (2).
Angle θ _ATarget step angle θ_TCalculate the vehicle vertical speed
Degree X_2i'Is negative, that is, when the vehicle body is in the descending direction,
Step angle θ based on calculated attenuation coefficient C_CSide goals
Step angle θ_TIs calculated, so that the valve body 31 is turned off.
The replacement area is the same as that of the skyhook control described above.
And the damping coefficient C is equal to the vehicle vertical speed X _2i及
And relative speed X_Di'On the vehicle instead of being calculated based on
Lower speed X_2i'Is changed based on the point calculated based only on'
The position is only slightly shifted, and the variable damping force
The minimum damping force control on the compression side or extension side of the absorber 3i is a valve
The flow path on the compression side and the extension side differs depending on the switching position of the body 31
It is automatically performed by the
There is no change and the riding comfort is slightly reduced.
In this case, almost the same control can be continued.
Changes have a significant effect on steering stability and ride comfort.
Can be reliably avoided.

In the above embodiment, the case where the variable damping force shock absorber is applied as the suspension device has been described. However, 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 element 31 for controlling the damping force is configured as a rotary type is described. However, the present invention is not limited to this. Different flow paths may be formed. In this case, a pinion is connected to the rotating shaft 41a of the step motors 41FL to 41RR, and a rack meshing with the pinion is attached to the connecting rod 42 or an electromagnetic solenoid is applied. Then, the sliding position of the valve element 31 may be controlled.

Further, in the above-described embodiment, from the road surface
When changing the body posture due to vibration input
However, the present invention is not limited to this.
, Etc., and detect changes in vehicle body posture due to this.
The suppression control may be performed together. Even better
In the above embodiment, the microcomputer 56
The case where control is performed by applying
The vertical acceleration is not specified, as shown in FIG.
The output of the degree sensor 51i is integrated by the integrator 61 and the
Speed X _2i′ And the stroke sensor 52i
Is differentiated by a differentiating circuit 62 to calculate a relative speed X._Di′
In addition, the output of the stroke sensor 52i is set to an allowable range.
Upper limit U to represent_SAnd lower limit L_SAnomaly detection hand set with
Supply to the window comparator 63 as a stage to allow
When the value is out of the range, for example, an abnormality detection signal having a logical value “1”
To get the vehicle vertical speed X_2i'And relative speed
X_Di'To the arithmetic circuit 64 for performing the operation of the above equation (1).
And the vehicle vertical speed X_2i'Is calculated by the above equation (2).
And calculates the attenuation coefficient C respectively.
Then, each of the calculated attenuation coefficients C has a logical value
When it is “0”, the output of the arithmetic circuit 64 is selected,
Selection of selecting the output of the arithmetic circuit 65 when the value is “1”
The selection circuit 66 supplies the selected output to the
The data is supplied to the data drive circuit 67 and the attenuation corresponding to the attenuation coefficient C is provided.
Calculate the step control amount that generates the force, and
Outputting a step pulse to the step motor 41i
Controls the damping force of the variable damping force shock absorber 3.
You may control it.

[0037] Still further, in the above embodiment, when an abnormality has occurred in the stroke sensor 52i, there has been described a case where the skyhook approximation control, is not limited to this, just the vehicle body vertical velocity X _2i ′ May be determined to be a predetermined value abnormality, and the damping force may be turned on and off in two levels of high and low. Further, in the above embodiment, the case where the potentiometer is applied as the stroke sensor has been described.However, the present invention is not limited to this, and an ultrasonic distance sensor and a detection coil for detecting the relative distance between the vehicle body and the road surface are used. Any relative displacement detection means such as a displacement sensor that detects displacement by impedance change or inductance change can be applied.

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

[0039]

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

[Brief description of the drawings]

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

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

FIG. 3 is a partially sectional front view showing an example of a variable damping force shock absorber.

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

FIGS. 5A and 5B are enlarged cross-sectional views showing a damping force adjusting mechanism in an intermediate damping force state when the vehicle body is lifted, wherein FIG. 5A shows a hydraulic oil path on the extension side and FIG.

FIGS. 6A and 6B are enlarged cross-sectional views showing a damping force adjustment mechanism when the vehicle body does not fluctuate, wherein FIG. 6A shows a hydraulic oil path on the extension side and FIG.

FIGS. 7A and 7B are enlarged cross-sectional views showing a damping force adjusting mechanism in a state of maximum damping force when the vehicle body descends, wherein FIG. 7A shows a hydraulic oil path on the extension side and FIG.

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

FIG. 9 is a block diagram illustrating 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-1RR Wheel 2 Body 3FL-3RR Variable damping force variable shock absorber 4 Controller 8 Piston 11 Lower half 12 Upper half 13 Extension oil flow path 14 Compression oil flow path 18 Extension disc valve 19 Compression disk valve 28 Compression 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 Differentiator circuit 63 Window comparator (abnormality detection means) 64, 65 Operation circuit 65 Selection circuit 66 Motor drive circuit

Claims (1)

(57) [Claims] A suspension device capable of changing a vehicle body posture change suppression characteristic in response to an input control signal interposed between a vehicle body-side member and a wheel-side member; A vertical acceleration detecting means for detecting a vertical acceleration, a relative displacement detecting means for detecting a relative displacement between the vehicle body side member and the wheel side member, and a vertical displacement detection value of the vertical acceleration detecting means and a 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 posture of the vehicle body based on the 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 of the control means is changed so as to form a control signal based only on the vertical acceleration detection value. A suspension control device, comprising: a control change unit.