JP3087519B2 - 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 controlling so-called semi-active control or the like which controls a control characteristic of a suspension 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 accordance with 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 member Relative displacement detecting means for detecting the relative displacement of the vehicle, and control means for forming and outputting the control signal for suppressing a change in the posture of the vehicle body based on the vertical acceleration detection value and the relative displacement detection value of the vertical acceleration detecting means. A suspension control device that outputs a control signal from the control means to the suspension device until the vehicle body posture change suppression characteristic changes. A system delay detecting means for detecting a delay, and when the system delay detected by the system delay detecting means is equal to or more than a set value, forming a control signal based on only the vertical acceleration detection value in a control mode by the control means. And a control changing means for changing the value as described above.

[0006]

According to the present invention, when the control system is normal and the system delay from when the control means outputs the control signal to when the attitude change suppression characteristic of the suspension device is changed is small, the vertical acceleration detection value By controlling the suspension device by forming a control signal based on the relative displacement detection value and controlling the suspension device, for example, skyhook control is performed to suppress a change in the attitude of the vehicle body, and vibration input from the road surface is cut off. When a large system delay occurs when the durability of the system is deteriorated or when the system is cold or cold, the deterioration of the damping performance caused by the difference between the target value and the actual value in the skyhook control is increased. By performing skyhook approximation control that forms a control signal based only on the acceleration detection value, the control is suppressed, and a good vibration suppression effect is exhibited.

[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). further,
The step motors 41FL to 4RR have end portions on the opposite side to the connecting rod 42 of the rotary shaft 41a.
Rotary potentiometers 44FL to 44RR that output analog voltages corresponding to the step angle of 1RR as step angle detection values θ _{PFL to} θ _PRR are connected.

The controller 4 has, on its input side,
As shown in the figure, the aforementioned rotary potentiometer 44
Vertical acceleration detection values _X2FL ″ to X, which are analog voltages that are upward and positive and downward and negative, according to FL to 44RR and the vertical acceleration provided on the vehicle body corresponding to each wheel position.
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 1F L} ) ~X DRR (= X 2RR -
A stroke sensor 52FL~52RR as relative displacement detecting means for outputting a X _1RR), a vehicle speed sensor 53 which outputs a vehicle speed detection value V corresponding to the vehicle speed are connected by detecting the vehicle speed, the damping force variable at the output side Shock absorber 3FL-3
Step motors 41FL to 41RR for controlling the damping force of RR are connected.

The controller 4 includes a microcomputer 56 having at least an input interface circuit 56a, an output interface circuit 56b, an arithmetic processing device 56c, and a storage device 56d, and step angle detection values θ _{PFL to} θ _{PRR of the} rotary potentiometers 44FL to 44RR.
Is converted to a digital value and the input interface circuit 56
A / D converters 55FL to 55RR to be supplied to a and vertical acceleration detection values X _2FL ″ to vertical acceleration sensors 51FL to 51RR.
A / D converters 57FL to 57RR for converting X _2RR ″ into digital values and supplying the digital values to the input interface circuit 56a;
The relative displacement detection value X of the stroke sensors 51FL to 51RR
A / D converters 58FL to 58RR which convert _{DFL to XDRR} into digital values and supply the digital values to input interface circuit 56a
And a step control signal for each of the step motors 41FL-41RR output from the output interface circuit 56b. The motor drive circuit 59 converts the step control signals into step pulses and drives each of the step motors 41FL-41RR.
FL to 59RR.

Here, the arithmetic processing unit 56c of the microcomputer 56 determines the step angle detection values θ _{PFL to} θ _{PRR of the} potentiometers 44FL to 44RR at a predetermined time, for example, when the vehicle stops.
Are monitored, and from the time when a step control signal corresponding to a predetermined step control amount is output, the step motors 41FL-41
RR detects a system delay time .DELTA..tau _M until reaching the step amount corresponding body detected system delay time .DELTA..tau _M is inputted from the vertical acceleration sensor 51FL~51RR in normal time is less than preset reference value tau _S Vehicle vertical speed X obtained by integrating the vertical acceleration detection values X _2FL ″ to X _2RR ″
_2FL 'to _X2RR ' and the relative displacement detection value X between the wheels and the vehicle body input from the stroke sensors 52FL to 52RR.
_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. calculating a step angle theta _T, and calculates and outputs the difference value between the target step angle theta _T and the current step angle theta _P, the step control amount according to the motor drive circuit 59FL～59RR, system delays the abnormal condition is time .DELTA..tau _M reference value tau _S or vertical acceleration detection value X _2j "
Based on the above, a damping coefficient C for performing skyhook approximation control approximating to the skyhook control is calculated, and a step control amount corresponding to this is output to the motor drive circuits 59FL to 59RR. Further, the storage device 56d stores the arithmetic processing device 56d.
A program necessary for the calculation processing of c is stored in advance, and values and calculation results required in the calculation processing are sequentially stored.

Next, the operation of the above embodiment will be described with reference to a micro computer.
Shows an example of the processing procedure of the arithmetic processing unit 56c of the computer 56.
This will be described with reference to FIGS. That is, FIG.
0 processing is a timer interrupt every predetermined time (for example, 10 msec)
First, in step S1, the vehicle speed sensor 5
3 is read, and then the process proceeds to step S2.
Then, it is determined whether or not the vehicle is in a stopped state in which the vehicle speed detection value V is zero.
judge. Here, when the vehicle is in a stopped state where V = 0,
Moves to step S3 and executes the system delay determination process.
After that, the process proceeds to step S5, where the traveling state is V ≠ 0.
If it is in the state, the process proceeds to step S4, and the system
The control flag F1 described later in the determination process is set to “0”.
Clear and system delay time Δτ ₁~ Δτ_NPassing
And Δτ_MIs cleared, and the process proceeds to step S5.

In step S5, each vertical acceleration sensor 5
1i (i = FL, FR, RL, and RR), the vertical acceleration detection values X _2i ″ are read, and then the process proceeds to step S6 to read the relative displacement detection values X _Di , and then the process proceeds to step S7. Vertical acceleration detection value X _2i ″ read in step S5
Are processed by, for example, low-pass filtering to calculate the vehicle body vertical speed X _2i ′, and these are stored in the storage device 56d.
Is temporarily stored in a predetermined storage area, and then the process proceeds to step S8 to differentiate the relative displacement detection value X _Di read in step S2 by, for example, high-pass filter processing to calculate a relative speed X _Di ′. After temporarily storing the data in a predetermined storage area of the storage device 56d, the process proceeds to step S9.

In this step S9, it is determined whether or not an abnormal flag FA set in a later-described system delay judging process is set to "1". If the abnormal flag FA is reset to "0", the system is reset. It is determined that the system is normal with a small delay, and when the abnormality flag FA is set to “1”, it is determined that the system delay is a large abnormality.

The result of the determination in step S9 is FA =
If it is "0", the flow shifts to step S10, and the vehicle body vertical speed X _2i 'calculated in steps S7 and S8.
Based on the relative speed X _Di 'and the following equation (1), a damping coefficient C for performing skyhook control is calculated. C = C _{S ×} X _2i ′ / X _Di ′ (1) where C _S is a preset damper damping coefficient.

Next, the routine proceeds to step S11, where the damping coefficient C calculated in step S10 is set to the minimum damping force C of the preset damping force variable shock absorber 3i.
Determines whether a _MIN or less, when it is C> C _MIN, the process proceeds 'to determine whether is positive, X _2i' body vertical velocity X _2i to step S12 when> 0 ,
In step S13, the target step angle θ _{Ti is determined} by referring to the region from θ _A to θ _B1 of the control map corresponding to FIG. 8 so that the damping coefficient C calculated in step S10 is set on the extension side. Then, the process proceeds to step S14.

In this step S14, the detected value θ _Pi of each step of the potentiometer 44i is read, and then the process proceeds to step S15 to calculate the deviation between the read step angle θ _Pi and the target step angle θ _Ti , It is updated and stored in a predetermined storage area of the storage device 56d as the control amount S,
Next, the process proceeds to step S16, where the step control amount S stored in the predetermined storage area of the storage device 56d is output to the motor drive circuit 59i, and then the timer interrupt processing is terminated and the process returns to the predetermined main program. .

The result of the determination in step S12 is X _2i '.
If <0, the process proceeds to step S17, in which the damping coefficient C calculated in step S10 is set on the pressure side with reference to the regions θ _B2 to θ _C of the control map corresponding to FIG. After calculating the target step angle θ _Ti , the process proceeds to step S14. Further, when the determination result of step S11 is C ≦ C _MIN , step S18
To θ _B1 to θ _{B2 of} the control map corresponding to FIG.
After calculating the target step angle θ _Ti with reference to the region (1), the process proceeds to step S14.

On the other hand, the determination result of step S9 is F =
If it is an abnormal state of "1", the process proceeds to step S19, where the calculation of the following equation (2) is performed based only on the vehicle body vertical speed _X2i 'calculated in step S7, and the skyhook approximation is performed. After calculating the damping coefficient C for performing the 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.

As shown in FIG. 11, the system delay judging process in step S3 first includes a control flag F indicating whether or not to perform a system delay time calculating process in step S3a.
It is determined whether or not 1 is "1". If the control flag F1 is "1", the system delay determination processing is terminated as it is, and the process proceeds to step S5 described above.
When 1 is "0", the flow shifts to step S3b.

In this step S3b, the detected step angle θ _Pi of each potentiometer 44i is read, and then the process proceeds to step S3c, where the read step angle detected value θ is read.
_Pi set system delay judgment start step angle θ _ST
(Eg, the pressure side maximum step angle θ _{C at} which the pressure side becomes a high damping force) is determined, and when θ _Pi ≠ θ _ST , the current step angle θ _Pi is closer to the step angle θ _A. it is determined that the process proceeds to step S3d, returns the step pulse output command for rotating the stepping motor 41i counterclockwise from the output to the motor drive circuit 59i in step S3b, the determination result of step S3c is, theta _Pi =
If θ _ST , the process proceeds to step S3e.

In step S3e, a step pulse output stop command is sent to the motor drive circuit 59i,
The driving of the step motor 41i is stopped, and then the process proceeds to step S3f, where a step pulse output command for newly rotating the step motor 41i clockwise is sent to the motor driving circuit 59i, and the step motor 41i is driven clockwise. Let it start.

Then, the flow shifts to step S3g, in which a separately set software timer is set to start timing, then the flow shifts to step S3h, where the step angle detection value θ _Pi is read again, and then the flow advances to step S3i. Then, it is determined whether or not the step angle detection value θ _Pi has reached the stop step angle θ _ED which is a sufficient step amount for determining the system delay. If θ _Pi ≠ θ _ED , the stop step angle θ _{ED is determined.} Is determined to have not reached step S3
h, and when θ _Pi = θ _ED , it is determined that the stop step angle θ _ED has been reached, and the flow shifts to step S3j to stop the software timer, and the measured time is stored as the system delay time Δτ in the storage device. 56d, and then goes to step S3k, sends a step pulse output stop command to the motor drive circuit 59i, stops driving the step motor 41i, and then goes to step S3m. After incrementing the count value N representing the number of times of calculating the delay time by “1”, the process proceeds to step S3n.

In this step S3n, it is determined whether or not the count value N has reached a preset set value N _S.
When it is N _S, the process returns to step S3b, N =
When it is N _S, the process proceeds to step S3o. In this step S3o, the count value N is cleared to zero, and then the process proceeds to step S3p, where the control flag F1 is set to "1", and then to step S3q.

In step S3q, the storage device 56d
The system delay time .DELTA..tau predetermined number N stored read, calculates the average of these systems delay time .DELTA..tau _M in,
At a step S3r, when the average system delay time .DELTA..tau _M the calculated is determined whether a set delay time tau _S above a preset, a Δτ _M <τ _S is
When it is determined that the system delay is small, the process proceeds to step S3s, and the abnormality flag FA is reset to "0". Then, the system delay determination process is terminated, and the process proceeds to step S5, where Δτ _M
When ≧ τ _S, it is determined that the system delay is large, and the process proceeds to step S3t, where the abnormality flag FA is set to “1”, and then the system delay determination process is terminated, and the process proceeds to step S3.
Move to 5.

In the processing of FIGS. 10 and 11,
The processing of steps S1 to S4 and the processing of FIG. 11 correspond to the system delay detecting means, and steps S5 to S8,
Steps S10 to S18 correspond to the control means, and
9 and S19 correspond to the control change means. Therefore, it is assumed that the vehicle is in a stopped state by stopping the engine and the ignition switch is turned on to start the engine from this state.
After the predetermined initialization for clearing the system delay time Δτ, the number of times N, the flags F1, FA, and the like stored in the CPU, the processes of FIGS. 10 and 11 are started at predetermined time intervals.

At this time, since the vehicle is at a standstill, the detected vehicle speed value V read in step S1 is zero, so that the process shifts from step S2 to step S3 to execute a system delay determination process. In this system delay determination processing, the step angle detection value θ _Pi of the potentiometer 44i is read, and it is determined whether or not this value matches a predetermined determination start step angle θ _ST. The process shifts to S3d, where a step pulse output command for driving the step motor 41i in the counterclockwise direction is output to the motor drive circuit 59i. In response to this, a step pulse for driving the step motor 41i to rotate counterclockwise is output from the motor drive circuit 59i to the step motor 41i, and the step motor 41i is driven to rotate counterclockwise.

When the detected step angle θ _Pi coincides with the determination start step angle θ _ST , the process shifts from step S3c to step S3e, and a step pulse output stop command is output to the motor drive circuit 59i. The step pulse output from the motor drive circuit 59i to the step motor 41i is stopped, whereby the rotation of the step motor 41i is stopped.

Thereafter, in step S3f, a clockwise step pulse transmission command is transmitted to the motor drive circuit 59i to determine a system delay, and thereby the motor 41
i starts rotating clockwise, and at this time a timer is set to start timekeeping. Then, wait until the step angle detection value theta _Pi reaches the determination end step angle theta _ED, the step angle detection value theta _Pi reaches the determination end step angle theta _ED, the process proceeds to step S3j, it stops the timer Then, the count value at that time is stored as a system delay time Δτ in a predetermined storage area of the storage device 56d, and then, in step S3k, a step pulse output stop command is sent to the motor drive circuit 59i, and the step motor 41i
The rotational shifts after stopping the step S3m incremented by "1" to determine the number of times N by, then determines whether the determination number of times N in Step S3n has reached the set number N _S, N <N _S If N = N _S , it is determined that the collection of the predetermined number of system delay times Δτ has been completed, the number of determinations N is cleared to “0”, and the control flag F1 is reset. "1" is set to, and divided by the predetermined number of system delay time .DELTA..tau a predetermined number in step S3q calculating the average system delay time .DELTA..tau _M.

[0038] Then, the average system delay time .DELTA..tau _M which is calculated to determine whether a set value tau _S above, .DELTA..tau _M
If <τ _S, it is determined that the system delay is small and the system is in a normal state, and the flow shifts to step S3s. After resetting the abnormal flag FA to “0”, the system delay determination process ends and the flow shifts to step S5. However, when Δτ _M ≧ τ _S , it is determined that the system delay is large and it is difficult to continue the normal control state, and step S3 is performed.
The process proceeds to t, sets the abnormality flag FA to "1", ends the system delay determination process, and proceeds to step S5.

Here, once the system delay is determined while the vehicle is stopped, the control flag F1 is set to "1".
3a, the system delay determination processing is terminated as it is.
Unnecessary changes in the damping coefficient due to driving i can be prevented to improve riding comfort.

When it is determined that the system is normal in the system delay determination processing, the abnormality flag FA is reset to "0". Therefore, when the processing of FIG. 10 is executed, the processing shifts from step S9 to step S10. . Therefore,
When the vehicle is stopped and the occupant does not get on and off, there is no vertical movement of the vehicle body and no relative displacement between the vehicle body and the wheels occurs. Therefore, the vehicle body vertical speed X _2i ′ calculated in steps S7 and S8. And the relative speed X _Di ′ both maintain zero, and the damping coefficient C calculated in step S10.
Becomes substantially zero, the process proceeds to step S18,
A target step angle θ _Ti (θ _{B1 to} θ _B2 ) to be set for the minimum damping coefficients C _nMIN and _{Ca MIN} is calculated on both the extension side and the _compression side of the damping force variable shock absorber 3i, and the target step angle θ _Pi is calculated. , And outputs the step control amount S to the motor drive circuit 59i to drive the step motor 41i to coincide with the target step angle θ _Ti to minimize the damping force of the damping force variable shock absorber 3i. Keep in state.

In this stopped state, when the occupant gets on and off and the vehicle body moves up and down and a relative displacement is generated between the vehicle body and the wheels, the vehicle body vertical speed X _2i ′ and the relative speed X _Di ′ corresponding thereto are changed. Therefore, the skyhook control damping coefficient C for suppressing these is calculated in step S10, and the target step angle θ _Ti for suppressing the vertical movement of the vehicle body is calculated based on the direction of the vehicle vertical speed X _2i ′. The step motor 41i is driven to rotate at a step angle corresponding to the above, and a damping force for suppressing the vertical movement of the vehicle body is generated, thereby exhibiting a vibration damping effect.

Thereafter, when the vehicle travels straight on a flat good road, there is almost no vertical movement of the vehicle even in this case. Therefore, the vehicle vertical speed X _2i 'and the relative speed calculated in steps S7 and S8 are obtained. X _Di 'also becomes substantially zero, and the step angle θ _{B1 to} θ _B2 within the range of the step angles θ _{B1 to} θ _B2 at which the extension-side and _compression- side minimum damping coefficients C _nMIN and C _aMIN are obtained in the same manner as when the vehicle is stopped without the occupant getting on and off. set the angle theta _T, step angle of the stepping motor 41i is driven to match the target step angle theta _T. Therefore, the valve elements 31 of the damping force variable shock absorbers 3FL to 3RR are set at the position B shown in FIG. 6, whereby the extension coefficient and the compression coefficient C of the piston 8 are respectively reduced to the minimum damping coefficient C.
Set to _nMIN and _CaMIN . 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 variable damping force shock absorber 3i and are not transmitted to the vehicle body, so that good ride comfort can be secured.

In this good road traveling state, for example,
When passing through a temporary step such as a difference,
When the vehicle does not move up and down due to
_2i′ Remain zero, so that the minimum damping coefficient C_aMINAnd C
_nMINWhen the wheel climbs on the shoulder to maintain the condition
Can absorb the pushing force of
If you can't absorb the thrust up the step
The vehicle body is also displaced upward,
Body vertical speed X_2i'Increases in the positive direction. This
Like the vehicle vertical speed X_2i′ Increases in the positive direction,
Proceeding to step S13, the step angle θ in FIG._A~ Θ
_B1Target step angle θ according to the damping coefficient C in the region of_TiIs calculated
The valve of the variable damping force shock absorber 3i
The switching of the body 31 is controlled as shown in FIG. As a result,
Relative speed X by riding on step_Di′ Is negative, that is,
Displacement speed X_2i′ To the wheel side displacement speed X_1i′ Is faster
When the piston 8 moves to the compression side by
Decay coefficient C_aMINVibration input to the wheel side
Can be absorbed and get over the step from this state
As a result, the wheel-side climb speed is lower than the vehicle-body climb speed.
Relative speed X _DFL'~ X_DRR′ Is positive and
The stone 8 moves to the extension side. At this time,
Since the damping coefficient C has a large value, the vehicle body is prevented from rising.
When the body stops rising after that,
Body vertical speed X_2i'Becomes zero,
Step motor 41i is rotated counterclockwise
Position B, so that both the compression side and the extension side
Damping coefficient C_aMINAnd C_nMINAnd then the vehicle
When the descent starts, the vehicle vertical speed X_2i′ Is negative
In the direction from step S12 to step S12.
The process proceeds to step S17 and refers to the control map of FIG.
Angle θ_B2~ Θ_CTarget stage according to the damping coefficient C
Angle θ_TIs calculated, the valve element 31 is further deflected.
It is turned clockwise and turned to the turning position shown in FIG.
You. For this reason, the vehicle body descends and the relative speed X_Di′ Is negative
And the piston 8 moves to the compression side, the damping force
The large vibration suppression effect is exhibited
You.

Conversely, when the wheel passes through a step descending forward
First, the relative speed is determined by the rebound of the wheels.
X_Di′ Increases in the positive direction,
Because it does not move, the vehicle vertical speed X_2i′ Is zero,
The damping coefficient of the variable damping shock absorber 3i is the minimum damping
Coefficient C_aMINAnd C_nMINAnd allow the wheels to descend,
Thereafter, when the vehicle body starts to descend, the vehicle vertical speed X_2i′
Increases in the negative direction, the damping coefficient C becomes a large value.
And the step angle θ_B2~ Θ_CTarget step angle θ in the range_Ti
Is calculated, and the valve element 31 is moved to the position shown in FIG.
Since the piston 8 is rotated, it is large against the movement of
Large damping force to exert a great damping effect.
Then the vehicle vertical speed X_2i′ Becomes smaller and the damping coefficient
As C becomes smaller, the valve element 31 is rotated clockwise.
To the position B side, and the vehicle body vertical speed X_2i′ Becomes zero
And the valve element 31 is in the position B, and the minimum damping coefficient C_aMINPassing
And C_{nM IN}Becomes After that, the car body lifted by swinging back
Starts, the vehicle vertical speed X _2i′ Increases in the positive direction
Together with the relative speed X_Di′ Is in the positive direction,
Step angle θ with increasing decay coefficient C_ATarget goal side
Step angle θ_TiIs calculated, and the valve element 31 rotates clockwise.
As a result, the piston 8 moves to the position shown in FIG.
Gives a large damping force to the extension side movement to reduce the vibration
Can be demonstrated.

As described above, when the vehicle travels on a temporary bump while traveling on a good road, a good vibration damping effect can be exerted by the skyhook control. In addition, the target step angle θ _Ti on the step angle θ _A side (or the step angle θ _C side) is calculated based on the positive (or negative) of the vehicle body vertical speeds X _2FL ′ to X _2RR ′, thereby raising the vehicle body. 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 running 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.

On the other hand, when the operating oil enclosed in the variable damping force shock absorber 3i becomes high in viscosity, such as in a stopped state in a cold region, the system is delayed, or the system is delayed due to deterioration of the durability of the system. If this occurs, when the processing of FIGS. 10 and 11 is executed while the vehicle is stopped, the system delay determination processing determines that the system delay is large and normal skyhook control is difficult. Since the abnormality flag FA is set to "1", the process shifts from step S9 to step S19, so that the control mode is the vehicle vertical speed _X2i 'and the relative speed _XDi '.
_Is changed to the skyhook approximate control based only on the vehicle body vertical speed _X2i .

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_TiCalculate 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_TiIs 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′.

However, the minimum damping force control on the compression side or the expansion side of the variable damping force shock absorber 3i is performed by the valve body 31.
Since the pressure-side and extension-side flow paths are different depending on the switching position, the mechanical control is automatically performed automatically. Therefore, the minimum damping force control is not changed at all from the skyhook control, and the control mode is substantially the same. Can continue. In addition, according to the skyhook approximation control, the damping coefficient C is calculated based only on the vehicle body vertical speed X _2i ′ obtained by integrating the vehicle body vertical acceleration detection value X _2i ″ according to the equation (2). The frequency, ie the sprung vibration frequency, is 1
２2 Hz, which is sufficiently lower than the unsprung vibration frequency of about 10 Hz. Therefore, even when the system delay time Δτ is large, as shown in FIG.
On the other hand, the tracking ability of the damping coefficient Cu by the skyhook approximation control shown by the broken line is good, and the area of the target coefficient Cob that protrudes is small, so that a good vibration damping effect can be exhibited.

Incidentally, in a state where the system delay time Δτ is large, the attenuation coefficient C is calculated according to the above-mentioned equation (1).
When performing skyhook control based on this, FIG.
As shown by the solid line in FIG. 2, the difference from the target damping coefficient Cob becomes large, the protruding area becomes large, and the damping performance deteriorates. As described above, according to the above-described embodiment, when the system delay time Δτ becomes larger than the set value due to a cold region or system durability deterioration, etc., based on the normal vehicle body vertical speed X _2i ′ and the relative speed X _Di ′. Since the skyhook control for calculating the damping coefficient C is switched to the skyhook approximation control for calculating the damping coefficient C based only on the vehicle body vertical speed X _2i ′, the influence of the system delay is suppressed to a minimum. Since the vibration control state can be continued,
It is possible to reliably prevent a large change in the control mode from greatly affecting the steering stability and the riding comfort as in the case of stopping the vibration suppression control.

In the above-described embodiment, the case where the system delay is determined by measuring the system delay time Δτ when the vehicle stops is described. However, the present invention is not limited to this. When the control state of the step angle that matches the preset system delay measurement range occurs, the system delay may be determined by measuring the system delay time Δτ, and the measurement range of the step angle may be arbitrarily set. can do.

Further, in the above embodiment, the case where the system delay time Δτ is measured a predetermined number of times and the average value is used to determine the system delay has been described. However, the present invention is not limited to this. The system delay may be determined based on the value. Further, the system delay time Δτ is measured several times, and the system delay time Δτ is measured.
May exceed the set value τ _S for a predetermined number of times, it may be determined that the system delay is large.

Further, in the above-described embodiment, the case where the variable damping force shock absorber having the damping characteristic shown in FIG. 8 is applied as the variable damping force shock absorber is described. It is also possible to apply a variable damping force shock absorber provided with a variable orifice whose opening area that can bypass these fixed orifices can be changed by an electric accumulator. In this case, the direction of the vehicle body vertical speed X _2i ′, From the direction of the relative speed X _Di ', it is determined whether the direction is the vibration damping direction or the vibration direction. When X _2i ' · X _Di '> 0, the vibration damping direction is determined, and the skyhook control damping coefficient Ck or Skyhook approximation control damping coefficient Cu is controlled, and when X _2i ′ · X _Di ′ ≦ 0, it is determined to be the vibration direction and is controlled to the minimum damping force C _MIN .

Further, in the above-described embodiment, the case where the step angle of the step motor is detected by the rotary potentiometer has been described. However, the present invention is not limited to this, and an arbitrary rotation angle detecting means such as a rotary encoder may be applied. I can do it. Further, in the above-described 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.

Further, in the above-described 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, 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 controller is
A description will be given of a case where the
However, the present invention is not limited to this.
Thus, the output of the vertical acceleration sensor 51i is integrated and
Lower speed X_2i', An integrator for calculating'
Differentiate the output of i and calculate the relative speed X _Di′ To calculate ′
Route, system delay time counter, count
Comparator that compares the vehicle speed with the set value, the vehicle vertical speed X_2i及
And relative speed X_Di'Based on the expression (1)
Calculation circuit, body vertical speed X_2i'Based on the above equation (2)
An arithmetic circuit that performs the operation of
Selection circuit for selecting the output of the arithmetic circuit, selection of this selection circuit
Motor drive circuit that drives the step motor based on the output
It may be configured by combining electronic circuits such as roads.
No.

Furthermore, in the above-described 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 for detecting the relative distance between the vehicle body and the road surface, Any relative displacement detection means such as a displacement sensor that detects displacement by a change in impedance or a change in inductance using a coil can be applied.

In the above embodiment, the vertical acceleration sensors 51FL to 51RR are located at the wheels 1FL to 1RR of the vehicle body 2.
Is described, but 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.

[0059]

As described above, according to the suspension control apparatus of the present invention, the vehicle body posture change suppression characteristic is changed according to the input control signal interposed between the vehicle body side member and the wheel side member. A suspension device capable of causing the vehicle, a vertical acceleration detecting means for detecting a vertical acceleration of the vehicle body at the position of the suspension device, a relative displacement detecting means for detecting a relative displacement of the vehicle body side member and the wheel side member,
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 a vertical acceleration detection value and a relative displacement detection value of the vertical acceleration detection unit. A system delay detecting means for detecting a system delay from when a signal is output to when the vehicle body posture change suppressing characteristic changes by the suspension device, and when the system delay detected by the system delay detecting means is equal to or more than a set value. And control change means for changing the control mode of the control means so as to form a control signal based only on the vertical acceleration detection value. When this happens, suspension characteristic control can be continued based only on the vertical acceleration detection value. As in the case where suspension characteristic control is stopped when the system delay time increases, an effect is obtained in which a change in suspension characteristics can be reliably prevented from greatly affecting 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 flowchart illustrating a subroutine of a system delay determination process in FIG. 10;

FIG. 12 is a characteristic diagram illustrating a relationship between a target damping coefficient change and an actual damping coefficient change in skyhook approximation control and skyhook control.

[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 44FL to 44RR potentiometer 51FL to 51RR vertical acceleration sensor 52FL to 52RR stroke sensor 56 micro Computer 59FL-59RR 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 of the vehicle body side member and the wheel side member, and a vehicle body based on the vertical acceleration detected value and the relative displacement detected value of the vertical acceleration detecting means. A control means for forming and outputting the control signal for suppressing the attitude change, wherein the control means outputs the control signal and then the suspension apparatus changes the vehicle body attitude change suppression characteristic. A system delay detecting means for detecting a system delay, and a system delay detected by the system delay detecting means being equal to or greater than a set value. And a control changing means for changing a control mode of the control means so as to form a control signal based only on the vertical acceleration detection value.