JP3102243B2 - 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 a so-called semi-active control in which a damping force of a variable damping force shock absorber is controlled based on at least a displacement speed of a vehicle body.

[0002]

2. Description of the Related Art A conventional semi-active type suspension control device is disclosed, for example, in Japanese Patent Application Laid-Open No. 3-42319.
Is described in Japanese Patent Application Publication No. In this conventional example, the expansion damping force and the compression damping force can be changed to at least a low damping force and a high damping force by adjusting the throttle opening by a rotary actuator such as a step motor by inputting a control signal. Shock absorber, sprung speed measuring means for measuring sprung speed, relative speed measuring means for measuring relative speed between sprung and unsprung, coincidence / mismatch of sign of sprung speed and sign of relative speed Sign determination means, and both signs match, and when the sign of the relative speed is positive, the extension side to high damping force, the compression side to low damping force,
Also, when both signs match, and when the sign of the relative speed is negative, a control signal for making the extension side low damping force and making the compression side high damping force is output.On the other hand, when both signs do not match, Control signal output means for outputting a control signal for reducing both the expansion side and the compression side to a low damping force.

[0003]

However, in the above-mentioned conventional suspension control apparatus, the damping force is varied by adjusting the throttle opening by a rotary actuator controlled by open loop. When the piston speed is low, there is no problem because the flow rate of the hydraulic oil passing through the throttle is also slow.However, when the piston speed is high, the flow rate of the hydraulic oil passing through the throttle is high, and the throttle opening is correspondingly increased. If the fluid force to be changed becomes large and exceeds the driving torque of the step motor, the motor will be out of step, causing a deviation between the actual control position and the target control position, and the control performance will be deteriorated. Issues.

Accordingly, the present invention has been made in view of the above-mentioned unsolved problems of the prior art. When the step-out state occurs, the control origin is immediately corrected, so that the control performance is surely reduced. It is an object of the present invention to provide a suspension control device capable of preventing the suspension.

[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. By controlling the rotation of the valve body by a step motor driven according to the input control signal,
A damping force variable shock absorber capable of individually controlling the extension side and the compression side damping force, a vertical acceleration detecting means for detecting a vertical acceleration at a position near the variable damping force shock absorber of the vehicle body, and at least a vertical acceleration detecting means. A suspension control device that calculates a damping force for suppressing a change in posture of the vehicle body based on the detected vertical acceleration value, and outputs the control signal corresponding to the damping force to the step motor to perform open loop control. A piston speed estimating means for estimating a piston speed of the damping force variable shock absorber; and controlling the step motor by the control means when the piston speed estimated by the piston speed estimating means is equal to or higher than a preset speed. and a control origin calibration means for outputting an origin calibration command to perform the origin calibration forcibly, Setting whose serial piston speed is set in advance
When the speed is equal to or higher than the speed,
After performing the correction, the control signal is output to the step motor.
It is characterized by power .

[0006]

According to the present invention, the piston speed of the variable damping force shock absorber is estimated by piston speed estimating means.
When the estimated piston speed becomes equal to or higher than a preset speed, it is determined that step-out may occur in the step motor, and the control origin calibration means forcibly causes the control means to perform control origin calibration. By doing so, the positional deviation between the actual control position and the target control position is eliminated.

[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 portion between the through holes 24a and 24b of the portion 21 so as to communicate with each other. Further, as shown in FIG.
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 position of the valve element 31 shown in FIG. 8, that is, the step angles of the step motors 41FL to 41RR described later. I have.

That is, at a position A in FIG. 8, which is the maximum rotation angle position in a clockwise direction when viewed from a plane, only the through hole 32 communicates with the arc-shaped groove 26 as shown in FIG. Moves downward from the lower pressure chamber 9L through the pressure-side oil flow path 14 to the upper pressure chamber 9U through an orifice formed by the open end and the pressure-side disk valve 19. Channel C
1 through the inner peripheral surface of the valve body 31 from the lower pressure chamber 9L, through the through hole 32, the arc-shaped groove 26, the pressure side oil flow path 27, and through the orifice formed by the opening end and the pressure side disc valve 28. Pressure side flow path C2 shown by a broken line toward the upper pressure chamber 9U.
Is formed and the piston 8 moves upward on the extension side, the orifice formed by the open end and the extension side disc valve 18 from the upper pressure chamber 9U through the elongated groove 16 and the extension side flow path 13. Only the extension side flow path T1 shown by a broken line toward the lower pressure chamber 9L is formed, and a high damping force that rapidly increases in accordance with an increase in the piston speed is generated on the extension side, and is increased on the compression side. Generates a low damping force that increases slightly as the piston speed increases.

As shown in FIG. 5, the valve body 31 is rotated counterclockwise from the position A so that the communication groove 33 of the valve body 31 and the through hole 2 of the small-diameter shaft portion 21 are rotated.
4a and 25a are in communication with each other, and 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), the elongated groove 16, the annular groove 15U, the through hole 24a, the communication groove 33, the through hole 25a, Passing through the annular groove 15L and the long groove 17, the long groove 1
A flow path T2 is formed toward the lower pressure chamber 9L through an orifice formed by the pressure valve 7 and the pressure-side disk valve 18, and the maximum value of the damping force is increased as shown in FIG.
3 and the through-holes 24a, 25a of the small-diameter shaft portion 21 gradually decrease as the opening area increases, and as shown in FIG. To maintain the formed state, the minimum damping force state is maintained.

Further, when the valve body 31 is rotated counterclockwise as viewed from a plane to be near the position B, as shown in FIG. 6, a long hole 34 is formed between the through holes 25a and 25b of the valve body 31.
The communication is established. Therefore, the piston 8
As shown in FIG. 6 (a), the lower side passes through the long groove 16, the annular groove 15U, the through hole 25a, the long hole 34, and the hole 23a in parallel with the flow paths T1 and T2. 9L pressure chamber
Is formed, the extension-side damping force becomes the minimum damping force state, and the hole 23a and the long hole are provided for the movement of the piston 8 on the compression side in addition to the channels C1 and C2. 34, the through-hole 25a, the long groove 1 through the annular groove 15U.
6, the flow path C3 and the hole 23a, the long hole 34, the through hole 25b, the annular groove 15L, the through hole 24b, the communication groove 33,
A flow path C4 that reaches the long groove 16 through the through hole 24a and the annular groove 15U is formed, but maintains the minimum damping force state as shown in FIG.

Further, when the valve element 31 is rotated counterclockwise as viewed from a plane, the long hole 34 and the through holes 24b and 25b
And the opening area between the hole 34 and the long hole 34 at the rotation angle θ _B2 is reduced.
7, the opening area between the through hole 32 and the arc-shaped groove 26 gradually decreases from the rotation angle θ _B2 . Therefore, between the rotation angle θ _B2 and the maximum counterclockwise rotation angle θ _C ,
For the movement of the piston 8 on the extension side, the flow path T1 and the flow path T2 coexist, so that the minimum damping force state is maintained. As the opening area between them gradually decreases, the maximum damping force gradually increases, and when the valve body 31 reaches the position C, as shown in FIG. By being in the cutoff state, the flow path from the lower pressure chamber 9L to the upper pressure chamber 9U is only the flow path C1 with respect to the pressure side movement of the piston, 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).

As shown in FIG. 9, a projection 44 is formed on the rotating shaft 41a of each of the step motors 41FL to 41RR so that the valve body 31 reaches the position A or the position C. At this time, it comes into contact with the extension-side stopper 45 and the compression-side stopper 46 provided on the bracket 40 so as to restrict further rotation. As shown in FIG. 9, the controller 4 has, on its input side, a vertical acceleration composed of an analog voltage which is positive in the upward direction and negative in the downward direction according to the vertical acceleration provided on the vehicle body corresponding to each wheel position. vertical acceleration sensor 51FL~51RR as vertical acceleration detecting means for outputting a detection value X _2FL "~X _2RR" is connected, the variable damping force shock absorber 3 to the output side
Step motor 41FL-4 that controls the damping force of FL-3RR
1RR 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;
An A / D converter 57FL~57RR supplied to the input interface circuit 56a FL～51RR the vertical acceleration detection value X _2FL "~X _2RR" is converted into a digital value, each step motor which is output from the output interface circuit 56b 41
A step control signal for FL to 41RR is input, and is converted into a step pulse to convert each step motor 41FL to 41RR.
The motor drive circuits 59FL to 59RR for driving the 41RR are provided.

Here, the operation of the microcomputer 56
The processing device 56c calculates the vertical acceleration detection value X_2FL″ ~
X_2RR”Based on piston speed V_PEstimate this pis
Ton speed V _PIs the preset speed threshold V_PTLess than
The vehicle vertical acceleration detection value X_{2F L}"~ X_2RR″
Vertical speed X_2FL'~ X_2RR′
The extension side and compression side position P based on the vehicle vertical speed_TPassing
And P_CIs calculated, and these and the current position P_PDifference value from
Is calculated, and the step control amount corresponding to this is
Perform damping force control processing to output to circuits 59FL to 59RR
Is the piston speed V_PIs the speed threshold V_PTWhen it's over
Moves the protrusion 44 to the current position P_PCloser to
To return to the origin by temporarily contacting the
After performing point calibration initialization,
Perform control processing.

The storage device 56d stores the arithmetic processing device 5
A program necessary for the arithmetic processing of FIG. 6c is stored in advance, and values and operation results required in the arithmetic processing are sequentially stored. Next, the operation of the above embodiment will be described with reference to FIG. 11 showing an example of a processing procedure of the arithmetic processing unit 56c of the microcomputer 56.

That is, in the processing of FIG. 11, first, in step S1, the rotating shafts 41a of the step motors 41FL to 41RR are used.
The initialization process such as initializing the control origin calibration and setting various parameters by bringing the protrusions 44 formed in contact with the extension-side stopper 45 into contact, for example, is performed, and then proceeds to step S2. In this step S2, each vertical acceleration detection value X
_2i "(i = FL, FR, RL, RR) is read, and then the process proceeds to step S3, where the following equation (1) is calculated based on the vertical acceleration detection value X _2i " read in step S1. calculating the piston velocity estimates V _P Te.

V _P = − (m / k) s · X _2i ″ / {1+ (c / k) s} (1) where s is a Laplace operator, m is a sprung mass, and k Is a spring constant and c is a damping coefficient, that is, the sprung mass m is arranged via a spring element having a spring constant k and a damper element having a damping coefficient c parallel to the road surface as shown in FIG. When a simple model is considered, these equations of motion are: mx ₂ ″ + c (x ₂ ′ −x ₀ ′) + k (x ₂ −x ₀ , where x ₀ is the road surface displacement and x ₂ is the sprung displacement. ) = 0... (2) Here, x ₂ ″ is a sprung displacement x ₂
Are the sprung accelerations, x ₂ ′ and x ₀ ′, which are the first order differentials of the sprung displacement x ₂ and the road surface displacement x ₀ , and are the sprung speed and the road surface change speed.

[0023] Then, the piston velocity V _P of the shock absorber as a damper element is expressed by _{(x 2 '-x 0')} , as shown in FIG. 13, as an input the sprung acceleration x ₂ ", the piston Considering an input / output system that outputs the speed V _P (x ₂ ′ −x ₀ ′), its transfer function is − (m /
k) s / {1+ (c / k) s}, whereby the equation (2) can be obtained.

[0024] Then, the process proceeds to step S4, the absolute value of the calculated piston speed estimated value V _P | V _P | is equal to or speed threshold V _PT or more set in advance. This determination is made because the piston speed increases and the step motor 41
Is intended to determine whether a condition resulting loss of synchronism in FL~41RR, | V _P | when a <V _PT, it is judged that that does not cause loss of synchronism in the stepper motor 41FL～41RR, directly proceeds to step S6, | V _P | when a ≧ V _PT, it is determined that there is a possibility that out-of-step occurs to the step motor 41FL～41RR, the process proceeds to step S5,
The current position P _P stored in the storage device 56d reads, the extension side maximum position P _TMAX or compression side maximum position P to calculate the step control amount until either the closer _CMAX, the stopper 45 a projection 44 in this, A control origin calibration process for calculating an initialization step amount obtained by adding a preset step amount necessary for securely bringing the actuator into contact with the controller 46 and outputting the calculated initialization step amount to the motor drive circuits 59FL to 59RR is performed. Transition.

In step S6, the vehicle vertical acceleration X _2i ″ read in step S2 is integrated by performing a low-pass filter process to calculate the vehicle vertical speed X _2i ′. Then, the process proceeds to step S7. It is determined whether or not the calculated vehicle body vertical speed X _2i ′ is positive including zero, based on whether the piston rod 35 of the variable damping force shock absorber 3i is moving to the extension side or the compression side. And when X _2i ′ ≧ 0,
It is determined that the vehicle is moving to the extension side, and the process shifts to step S8 to change the vehicle body vertical speed X _2i ′ to the vehicle body vertical speed X _2TM when it _{reaches the preset} true maximum value P _TLMAX of the extension side position. It is determined whether or not the value X _2i '/ X _2TM ' divided by 1 exceeds 1; if X _2i '/ X _2TM '> 1, the _routine goes to step S9, where X _2i '/ X _2TM ′ = 1, and then proceeds to step S10, where X _2i ′ /
If X _2TM ′ ≦ 1, step S10
Move to

In step S10, the vehicle vertical speed X_2i′
And X_2TM'And the maximum position P on the extension side_TMAXAnd based on
The following formula (2) is used to calculate the target extension side position P._TTo
After the calculation, the process moves to step S11. P_T= (X_2i'/ X_2TM') P_TMAX (2) In this step S11, the data stored in the storage device 56d is stored.
Current position P _PAnd target position P_T(Or later
P to describe_C) And calculate this as the step control amount.
Update and store in a predetermined storage area of the storage device 56d as S
With the target position P_TOr P_CThe current position
P_PIs updated and stored, and then the process proceeds to step S12.
After the transition, the data is stored in a predetermined storage area of the storage device 56d.
Step control amount S is output to the motor drive circuit 59i.
Then, the process proceeds to step S13, and the predetermined control ends.
Judge whether the condition is satisfied or not and satisfy the control end condition.
If not, the process returns to step S2, and the control end condition
Is satisfied, the process ends. Here, the predetermined system
As an end condition, for example, the ignition switch
The self-holding period of the specified time
Is set when

On the other hand, if the determination result of step S7 is X_2i′ <
When it is 0, the damping force variable shock absorber 3i
It is determined that the piston rod 35 is moving to the compression side
Then, the process proceeds to step S14, and the vehicle vertical speed X_2i′
True maximum value P of the preset pressure side position_CMAXTona
Vehicle body vertical speed X_2CM'Divided by X_2i'/ X
_2CM′ Is greater than 1 and X_2i'/ X
_2CMIf '> 1, the process proceeds to step S15.
And X_2i'/ X_2CMAfter setting '= 1, step S1
6 and X_2i'/ X_2CMWhen '≤1,
Then, the process proceeds to step S16.

In step S16, the vehicle body vertical speed X _2i '
And performing the following calculation formula (3) proceeds from the calculated target compression side position P _C to the step S11 on the basis of the on and the compression side maximum position P _CMAX X _2CM '. P _C = (X _2i ′ / X _2CM ′) P _CMAX (3) In the processing of FIG. 11, the processing of steps S2 and S3 corresponds to the piston speed estimating means, and the processing of steps S4 and S5 is performed. Step S7 corresponds to the control origin calibration means.
Steps S16 to S16 correspond to the control means.

Therefore, when the ignition switch is turned on, the controller 4 is turned on, whereby the microcomputer 56 is turned on.
The processing of FIG. 11 is started by the arithmetic processing device 56c. Therefore, first, in step S1, the step motor 4
For example, the protrusion 44 is extended with respect to
After performing an initialization process for setting the control origin by temporarily abutting the control portion 5 and setting processing of various parameters, the process proceeds to the damping force control process after step S2.

At this time, since the vehicle is in a stopped state, assuming that there is no occupant getting on / off or loading / unloading of the load, the vehicle body does not swing and the vertical acceleration sensor 51
The vertical acceleration detection value X _2FL is output from FL~51RR "~
X _2RR "is substantially equal to zero Thus, since the piston velocity estimates V _P calculated in step S3 becomes substantially zero,. |
V _P | <V _PT , and the step S4 is performed directly from the step S4.
6, since the vehicle body vertical speeds X _2FL ′ to X _2RR ′ are also substantially zero, the process proceeds from step S7 to step S10 via step S8, and the extension target position _PT also has the vehicle body vertical speed X _2i ′ of zero. , And becomes zero.
Drive is performed so that 1FL-41RR matches the extension side target position _PT . For this reason, the valve elements 31 of the damping force variable shock absorbers 3FL to 3RR are set to the position B shown in FIG. 6, and thereby the damping force on the extension side and the compression side of the piston 8 is set to the soft state of the minimum state.

When the vehicle is started slowly from this stopped state and runs straight on a flat good road, the vehicle body hardly moves up and down again in this case.
Vertical acceleration detection value X _2FL ″ output from 1RR
X _2RR ″ becomes substantially zero, and the valve element 31 of the variable damping force shock absorbers 3FL to 3RR maintains the position B shown in FIG. 6, whereby the soft state in which the extension side and compression side damping forces of the piston 8 are in the minimum state. Therefore, 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. .

When the vehicle does not move up and down due to the passage of a temporary step such as a step rising upward in this good road running state, the vehicle vertical speed X
_{Since 2FL} 'to _X2RR ' are maintained at zero, to maintain the minimum damping force state, it is possible to absorb the thrust force when the wheel rides on the step, but ride on a relatively large step, If you can't absorb that thrust,
Body also would be displaced upward, thus resulting in the vehicle body vertical velocity X _2FL '~X _2RR' is increased in the positive direction. As described above, when the vehicle body vertical speeds X _2FL ′ to X _2RR ′ increase in the positive direction, the process proceeds to step S10 through step S8.
The process moves to, the extension side position P _T of the target maximum position P _TMAX side of the extension side position P _T1 in FIG. 8 is calculated, the valve body of the damping force variable shock absorber 3FL～3RR 3
1 is switched and controlled as shown in FIG. As a result, when the displacement speed X _1i ′ on the wheel side is faster than the displacement speed X _2i ′ on the vehicle body side due to the stepping over, and the piston 8 moves to the compression side, the compression-side minimum damping force is maintained. The vibration input to the wheel side can be absorbed, and when the climbing speed on the wheel side becomes lower than the climbing speed on the vehicle body side by going over the step from this state, the piston 8 moves to the extension side. At this time, since the damping force has a large value, the damping force exerts a damping effect of suppressing the rise of the vehicle body, and when the vehicle body stops rising thereafter, the vehicle body vertical speed _X2FL'- X
_{When 2RR} 'becomes zero, the step motors 41FL to 41RR are rotated counterclockwise and returned to the position B as described above, whereby both the compression side and the extension side are controlled to the minimum damping force, and then the vehicle body is When you start descending,
By the vehicle body vertical velocity X _2FL '~X _2RR' is increased in the negative direction in response to this, the step from the step S7 S1
4 shifts to step S16 via, by calculating the compression side target position P _C, the valve element 31 is rotated to further counterclockwise, it is rotated in the rotated position shown in FIG.
Therefore, when the vehicle body is lowered and the piston 8 moves to the pressure side, the damping force is increased, so that a large damping effect is exhibited.

When the wheel passes over the step, the damping force variable shock absorber 3 calculated in step S3 is used.
When the piston velocity estimates V _P of FL~3RR becomes more speed threshold V _PT, fluid force differential oil passing through the fluid passage of the piston 8 is increased, which may cause a loss of synchronism in the stepper motor 41FL~41RR However, in this case, step S
4 to step S5, the current position P
Extension side stopper 45 or compression side stopper 4 close to this from _P
The step motors 41FL to 41RR are rotated to the side 6 so that the projections 44 abut against the extension side stoppers 45 or the compression side stoppers 46. With the projections 44 abutting against the stoppers 45 or 46, the current position is set to the position A. Alternatively, after setting to C, the process proceeds to step S6. For this reason, even if the step motors 41FL to 41RR lose synchronization due to the fluid force, the position A or the position C serving as the control origin can be accurately calibrated, and the control deviation due to the influence of the loss of synchronization can be reliably removed. can do.

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, but the vehicle body does not move up and down at this time. Body vertical speed X _2FL '~ X
_{Since 2RR} 'is zero, the damping coefficients of the damping force variable shock absorbers 3FL to 3RR maintain the minimum damping force, allow the wheels to descend, and then the vehicle body starts to descend, and the vehicle vertical speed _X2FL ' When to X _2RR 'is increased in the negative direction, and the compression side target position P _C becomes a large value, since the valve body 31 is rotated to the position shown in FIG. 7, a large damping force against the movement of the compression side of the piston 8 To exert a large vibration damping effect, and thereafter, the vehicle vertical speed X _{2F L} ′ to X _2RR ′
Depending on the compression side target position P _C is smaller becomes small, the valve body 31 is returned to position B side is rotated clockwise, the vehicle body vertical velocity X _2FL '~X _{2R R'} is zero, the valve The body 31 becomes the position B and returns to the minimum damping force state. Then, when you start to rise by the vehicle body unwag, since the vehicle body vertical velocity X _2FL '~X _2RR' is increased in the positive direction increases the extension phase target position P _T, the valve element 31 is rotated clockwise As a result, a large damping force can be applied to the movement of the piston 8 on the extension side to exert the 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 a positive vehicle body vertical velocity X _2FL '~X _2RR' (or negative) by Shin-side target position P _T (or pressure side target position P _C) is calculated, the piston 8 body rises Gasing The damping force is controlled to the minimum damping force in the vibration direction in which the piston 8 moves to the compression side, and the piston 8 moves to the compression side when the body moves up and the piston 8 moves to the extension side. When it is in the vibration direction, the damping force is controlled to the optimum damping force according to the vertical speed X _2FL ′ to X _2RR ′,
Good ride comfort can be ensured.

Even when the vehicle is traveling on a rough road, the vehicle body rises and the piston 8 moves to the extension side, and the vehicle body descends and the piston moves to the compression side in the same manner as when the vehicle passes the step. The damping force is controlled to the minimum damping force in the vibration direction. Conversely, vibration suppression is performed when the vehicle body rises and the piston 8 moves to the compression side, and when the vehicle body descends and the piston moves to the extension side. When the damping force is in the vertical direction X
Control is made to an optimum value according to _2FL 'to _X2RR ', and a good ride comfort can be secured.

In the above embodiment, the case where the valve element 31 for controlling the damping force is formed in a rotary type is described. However, the present invention is not limited to this. Different flow paths may be formed on the side and in this case, in this case, step motors 41FL to 4FL
A pinion may be connected to the rotation shaft 41a of the 1RR, and a rack that meshes with the pinion may be attached to the connection rod 42 or an electromagnetic solenoid may be used to control the sliding position of the valve element 31.

Further, in the above embodiment, the case where the projections 44 are provided on the rotation shaft 41a of the step motors 41FL to 41RR and the stoppers 45 and 46 are provided on the bracket 40 has been described. A circular arc-shaped notch may be provided, and a protrusion engaging with the notch may be provided on the bracket 40.
In place of 5 and 46, a position detecting means such as a microswitch that engages with the protrusion 44 is provided, and when the position detecting means detects the protrusion 44, the driving of the step motors 41FL to 41RR is stopped, and the origin calibration is performed. It may be performed more accurately.

Further, in the above-described embodiment, the case where the skyhook approximation control in which the vertical acceleration of the vehicle body is detected and the damping force is controlled based on the detected acceleration is described, but the invention is not limited to this. Instead, a stroke sensor for detecting the relative displacement between the vehicle body and the wheels is separately provided, and the relative speed X _Di 'obtained by differentiating the relative displacement detection value X _Di of the stroke sensor and the vehicle body vertical speed X _2i ' described above. Calculates the damping coefficient C by performing the calculation of the following equation (3), and calculates the target position based on the damping coefficient C with reference to, for example, a map corresponding to FIG. You may do so.

C = C _{S ×} X _2i ′ / X _Di ′ (3) where C _S is a preset damper attenuation coefficient.
Furthermore, in the above-described embodiment, the case where the posture change of the vehicle body due to the vibration input from the road surface is suppressed has been described. However, the invention is not limited to this. Control for suppressing a change in the posture of the vehicle body may be performed together.

[0041] Still further, in the above embodiment, as a piston speed estimating means, has been described for calculating the piston velocity estimates V _P on the basis of the vertical acceleration detection value X _2i ", being limited thereto without arranged a stroke sensor in parallel with the damping force control shock absorber 3FL～3RR, may calculate the piston velocity estimates V _P by differentiating the stroke value detected by the stroke sensor.

In the above embodiment, the case where the control is performed by using the microcomputer 56 has been described. However, the present invention is not limited to this. The output of the vertical acceleration sensor 51i is integrated to calculate the vehicle vertical speed. An electronic circuit such as an integrator, an arithmetic circuit for estimating the piston speed, and an arithmetic circuit for calculating the target position can be combined.

Furthermore, in the above embodiment, the vertical acceleration sensors 51FL to 51FL are located at the wheels 1FL to 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, the damping force variable shock absorber is not limited to the above-described configuration, and the present invention can be applied to other damping force variable shock absorbers that can switch the damping force in two or more steps by a step motor.

[0044]

As described above, according to the suspension control apparatus of the present invention, the piston speed estimating means for estimating the piston speed of the damping force variable shock absorber, and the piston speed estimating value being set at a preset speed Control origin calibration means for calibrating the origin of the step motor when the above is provided , wherein the piston speed is set in advance.
When the speed is higher than the set speed, the control
After performing point calibration, the control signal is
Is configured to output the Runode, the damping force is variable shock absorber piston velocity is high, even if the step motor becomes out-of the influence of a fluid force due to hydraulic fluid passing through the piston, the control origin since a control signal from the I line the origin calibration calibration hand <br/> stage, there is an advantage that it is possible to perform accurate damping force control without causing the control deviation by step out.

[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 position of a valve body of a variable damping force shock absorber.

FIG. 9 is an enlarged sectional view taken on line AA of FIG. 3;

FIG. 10 is a block diagram illustrating an example of a controller.

FIG. 11 is a flowchart illustrating an example of a processing procedure of a controller.

FIG. 12 is an explanatory diagram showing a simplified model of a vehicle.

FIG. 13 is a block diagram for obtaining a piston speed.

[Explanation of symbols]

 DESCRIPTION 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 31 Valve element 35 Piston rod T1-T3 Extension side flow path C1-C4 Pressure side flow path 41FL-41RR Step motor 51FL-51RR Vertical acceleration sensor 56 Microcomputer 59FL-59RR Motor drive circuit

Claims (1)

(57) [Claims] A damping force on an extension side and a compression side by controlling rotation of a valve body by a step motor interposed between a vehicle body side member and a wheel side member and driven in accordance with an input control signal. Variable shock absorber capable of individually controlling the vertical acceleration, vertical acceleration detecting means for detecting vertical acceleration at a position near the damping force variable shock absorber of the vehicle body, and at least a vertical acceleration detection value of the vertical acceleration detecting means. A suspension control device that calculates a damping force for suppressing a change in the posture of the vehicle body and outputs the control signal corresponding to the damping force to the step motor to perform open-loop control. Piston speed estimating means for estimating the piston speed of the absorber, and the piston speed estimated by the piston speed estimating means being Control origin calibration means for outputting an origin calibration command for forcibly calibrating the control origin of the step motor by the control means when the set speed is equal to or higher than the set speed , wherein the piston speed is equal to or higher than a preset set speed.
When, calibration of the control origin of the step motor is performed.
After, the suspension control apparatus according to claim and this <br/> for outputting the control signal to the step motor.