JP3125415B2 - 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 an improvement of a suspension control device for controlling a stroke of an actuator interposed between a vehicle body and wheels based on road surface information ahead of the wheels.

[0002]

2. Description of the Related Art Conventional suspension control devices are disclosed in Japanese Patent Application Laid-Open Nos. 61-135811 (hereinafter referred to as a first conventional example) and Japanese Patent Application Laid-Open No. 60-193710 (hereinafter referred to as a second conventional example). Some are described in
The first conventional example is a vehicle shock absorber including a wheel that is rotationally driven along a road surface, and a spindle mechanism that supports the wheel and the vehicle body at a predetermined interval, and drives the spindle mechanism according to unevenness of the road surface. A detection unit disposed in front of the traveling of the wheels to detect the irregularities; a control unit for commanding expansion and contraction of the predetermined interval by a signal of the detection unit and a traveling speed signal; And a valve drive mechanism for exciting an electromagnetic valve so as to inject or discharge hydraulic pressure.

[0003] In a second conventional example, a detecting means for detecting the vertical movement of the front wheel, a road surface condition is estimated based on the detection result of the detecting means, and a calculation for obtaining control information for setting suspension characteristics corresponding to the road surface condition. Means, delay means for delaying the control information by a predetermined time in accordance with the vehicle speed, and an actuator for varying the characteristics of the rear wheel suspension by the delayed control information.

[0004]

However, in the suspension control devices of the first and second prior arts described above, a bouncing motion and a pitching motion of the vehicle body are generated by using a vibration input from a road surface as a vibrating force. Since the point that the motion continuously occurs even on a flat road is not considered, the influence of the bounce motion and the pitching motion is included in the road surface information detection value of the road front road surface information detecting means, and this front road surface information is used. There is an unsolved problem that if a control force is applied to the wheels, suspension control cannot accurately follow the road surface condition.

Therefore, the present invention focuses on the unsolved problem of the conventional example, and a suspension capable of performing accurate suspension control according to the road surface condition without being affected by a bounce motion or a pitching motion. It is intended to provide a control device.

[0006]

To achieve the above object, according to the Invention The suspension control apparatus according to the present invention is disposed between the wheel and the vehicle body, between <br/> the wheel and the vehicle body by a control signal an actuator for generating a controllable control force stroke of a front road surface information detection means for detecting road surface information of the wheel forward as an acceleration, a control for controlling the actuator based on the forward road information of the forward road surface information detection unit Information on acceleration generated in the vehicle body due to vibration of the front and rear wheels on the vehicle body
A vibration information detecting means for detecting, of the pressurized vibration information detecting means
Acceleration generated in the front road surface information detecting means from the acceleration information
Road surface information correction means for calculating a degree and correcting front road surface information of the front road surface information detection means based on the acceleration calculation value
It is characterized by comprising and.

Here, the forward road surface information detecting means includes:
Second order differential value of the distance between the body in front of the wheel and the road surface with respect to time
Is detected, and the detected value is used as forward road surface information.
Or the acceleration generated at the front wheels, and the detected value is
Actuator on the rear wheel side as front road surface information for
It is preferable to configure so as to control the data.

[0008] In the present invention, the front of the road surface information of the wheel to be controlled while <br/> detected as the acceleration in the forward road surface information detection unit, vehicle body by vibrating relative to the vehicle body based on the wheel of the movement information by the road surface input Of acceleration information
From the acceleration information to the front road surface information detecting means.
Calculated based on the calculated acceleration value.
By correcting the road information ahead of the road information detecting means, it is possible to obtain accurate road surface information from which the posture change due to the bouncing movement and the pitching movement of the vehicle body has been removed, and to accurately control the actuator according to the road surface state. Can be.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram showing an embodiment of the present invention. In the drawing, reference numeral 10 denotes a vehicle body side member, 11FL to 11RR indicate front left to rear right wheels, and 12 indicates a suspension control device.

The suspension control device 12 includes hydraulic cylinders 18FL-18RR as actuators interposed between the vehicle body-side member 10 and the respective wheel-side members 14 of the wheels 11FL-11RR, and the hydraulic cylinders 18FL-18RR.
Pressure control valves 20FL to 20RR to individually adjust the operating pressure of
A hydraulic source 22 that supplies hydraulic oil at a predetermined pressure to the pressure control valves 20FL to 20RR via a supply pipe 52, and collects return oil from the pressure control valves 20FL to 20RR through a return pipe 54; The accumulators 24F and 24R for accumulating pressure, which are inserted in the supply pressure side pipe 52 between the hydraulic pressure source 22 and the pressure control valves 20FL to 20RR, a vehicle speed sensor 26 for detecting the vehicle speed, and the front wheels 11FL and 1
Ultrasonic distance sensors 27FL, 27 as front road surface information detecting means disposed at positions ahead of these corresponding to 1FR.
FR, vertical acceleration sensors 28FL and 28RL as vibration state detecting means for individually detecting vertical acceleration at positions corresponding to the front left wheel 11FL and the rear left wheel 11RL on the vehicle body side member 10, and the ultrasonic distance measurement. Surface information correction circuit 29 for correcting road surface information based on the ground distance detection values H _FL and H _FR of devices 27FL and 27FR based on acceleration detection values Z _GFL and Z _GRL of vertical acceleration sensors 28FL and 28RL, and vehicle speed sensor 26 Speed sensors V and the ultrasonic sensors 27FL and 27FR output from the road surface information correction circuit 29
Pressure control valves 20FL-2 based on the corrected road surface information at the position
A controller 30 for individually controlling the output pressure of 0RR.

Each of the hydraulic cylinders 18FL to 18RR has a cylinder tube 18a.
8a, a lower pressure chamber L separated by a piston 18c having an axial through hole is formed.
A thrust corresponding to the pressure receiving area difference between the upper and lower surfaces and the internal pressure is generated.
The lower end of the cylinder tube 18a is
4 and the upper end of the piston rod 18b is attached to the vehicle body side member 10. Further, each of the pressure chambers L is connected to a pressure control valve 20FL-20RR via a hydraulic pipe 38.
Connected to the output port. Hydraulic cylinder 1
Each of the pressure chambers L of 8 FL to 18 RR is connected to an accumulator 34 for absorbing unsprung vibration through a throttle valve 32. A coil spring 36 having a relatively low spring constant and supporting the static load of the vehicle body is disposed between the upper and lower portions of each of the hydraulic cylinders 18FL to 18RR.

Each of the pressure control valves 20FL to 20RR has a well-known three-port proportional electromagnetic pressure reducing valve having a cylindrical valve housing having a spool slidably mounted therein and a proportional solenoid integrally provided therewith. (For example, Japanese Patent Application Laid-Open No. 64-7
No. 4111). Then, by adjusting the command current i (command value) supplied to the exciting coil of the proportional solenoid, the moving distance of the poppet housed in the valve housing, that is, the position of the spool is controlled, and the supply port and the output port or the output port are controlled. Hydraulic oil flowing between the hydraulic source 22 and the hydraulic cylinders 18FL to 18RR can be controlled via the port and the return port.

FIG. 2 shows the relationship between the command current i (: i _{FL to} i _RR ) applied to the exciting coil and the control pressure P output from the output port of the pressure control valve 20FL (to 20 _RR ). As described above, the minimum control pressure P _NIM is at the minimum current value i _MIN in consideration of noise. When the current value i is increased from this state, the control pressure P linearly increases in proportion to the current value i, when the current value i _MAX is the maximum control pressure P _MAX corresponding to the set line pressure of the hydraulic source 22. This figure 2
Where i _N is a neutral command current and P _N is a neutral control pressure.

Each of the ultrasonic distance measuring devices 27FL and 27FR includes an ultrasonic transmitter and an ultrasonic receiver (not shown), and emits ultrasonic pulses from the ultrasonic transmitter toward the ground. The distance to the ground is calculated by measuring the time from when the light is reflected on the ground to when it is received by the ultrasonic wave receiver, and the calculation result is output as ground distance detection values L _FL and L _FR which are analog voltages. .

The vertical acceleration sensors 28FL and 28RL
In each case, the vertical acceleration is zero as shown in FIG.
When zero voltage or upward acceleration is detected,
Positive analog voltage according to the acceleration value of the downward acceleration
Is detected, a negative analog corresponding to the acceleration value
Vertical acceleration detection value Z consisting of voltage_GFL,Z_GFRAnd Z
_GRLIs output.

The road information correction circuit 29, as shown in FIG. 4, a second-order differential circuit 41FL and 41FR to second order differential of the ultrasonic distance measuring device 27FL and 27FR of the ground distance detection value H _FL and H _FR, front and rear Vertical acceleration sensors 28FL and 28
Correction value H based on acceleration detection values Z _GFL and Z _GRL of RL
_A correction value calculation circuit 42 for calculating _A and a second-order differentiation circuit 41
_A subtractor 43 for individually subtracting the correction value _HA of the correction value calculation circuit 42 from the second derivative values H _FL ″ and H _FR ″ of FL and 41FR.
FL and 43FR, and subtracters 43FL and 43FR
Subtraction output of is output as a road acceleration estimated value H _GFL and H _GFR. Here, the correction value calculation circuit 42 calculates the bounce acceleration by adding the acceleration detection values Z _GFL and Z _GFR of the vertical acceleration sensors 28FL and 28FR to the adder 42a and dividing the added output by “2”. Division circuit 42
b and the acceleration detection value Z of the vertical acceleration sensor 28FL
_{From GFL} , acceleration detection value Z _GRL of vertical acceleration sensor 28RL
A subtracter 42c for subtracting the distance L _P of the 42d division circuit for calculating a pitching acceleration by dividing the subtraction output "2", until the ultrasonic distance measuring device 27FL and 27FR from the pitch center in the pitching acceleration It was divided by the distance L _F from the pitch center to the front wheels 11FL and 11FR value (L _P
/ L _F ) and multiplying by ultrasonic distance measuring devices 27FL and 27FR
A conversion circuit 42e for converting the acceleration due to the pitching motion at the position, a correction value H by adding the bounce acceleration of the division circuit 42b and the pitching acceleration of the conversion circuit 42e.
_And an adder 42f for calculating _A.

[0017] Then, correction road information outputted from the vehicle speed detection value V and the road information correction circuit 29 from the vehicle speed sensor 26 H _GFL and H _GFR is input to the controller 30. The controller 30, as shown in FIG. 4, the correction road information H _GFL and A / D converters 61FL and 61FR for converting and H _GFR into a digital signal, the vehicle speed detection value V,
A microcomputer 62 to which A / D conversion outputs of the A / D converters 61FL to 61FR are input, and pressure command values P _{FL to} P _RR output from the microcomputer 62 are D
/ A converter 63FL~63RR supplied via the drive current i _FL through i _FR those for the pressure control valve 20FL~20RR
For example, there are provided drive circuits 64FL to 64FR each configured by a floating constant voltage circuit.

The microcomputer 62 has at least an input interface circuit 62a, an output interface circuit 62b, an arithmetic processing unit 62c, and a storage device 62d. The input interface circuit 62a receives the vehicle speed detection value V and the conversion output of the A / D converters 61FL and 61FR, and outputs the pressure command values P _{FL to} P _RR from the output side interface circuit 62b to the D / A converters 63FL to 63FL. 63
Output to RR. Further, the arithmetic processing unit 62c executes the processing of FIG.
_S (for example, 20 msec), the corrected road surface information H _GFL , H
_{The GFR} is read and stored in the storage device 62d while shifting them by a predetermined number, and the road surface detected by the ultrasonic distance measuring devices 27FL and 27FR based on the vehicle speed detection value V is the front wheel 11
Calculate delay times τ _DF and τ _DR to reach FL, 11 FR and rear wheels 11 RL and 11 RR, and calculate these delay times τ _DF and τ
Based on the _DR , the current road surface information of each of the wheels 11FL to 11RR is selected, the selected road surface information is multiplied by a predetermined gain, and the pressure corresponding to the target vehicle height for maintaining the vehicle body at the target vehicle height is selected. The command value _PN is added and each pressure control valve 20FL ~
The pressure command values P _{FL to} P _RR for 20RR are calculated and output to the D / A converters 63FL to 63RR via the output interface circuit 62b. Further, the storage device 62d
, Together with the program required for the operation processing of the pre-processing unit 62c is stored, read uncorrected road information every predetermined time H _GFL, shift register area for storing a predetermined number while respectively sequentially shifting the H _GFR is formed Then, the result of the operation required in the operation process of the operation processing device 62c is sequentially stored.

Next, the operation of the above embodiment will be described with reference to the flowchart of FIG. 5 showing the processing procedure of the arithmetic processing unit 62c in the microcomputer 62. That is,
The processing in FIG. 5 is performed for a predetermined sampling time T _S (for example, 20 ms).
ec) is executed as a timer interrupt process. First, in step S1, the road surface information correction circuit 29 and the corrected road surface information H
_GFL and _HGFR are read, and then the process _proceeds to step S2 to store the read corrected road surface information _HGFL and _HGFR in the storage device 6.
Stores the start storage unit of the shift register region formed in 2d, the correction of a predetermined number which is stored in up to the previous road information H _GFL, sequentially shifts the H _GFR.

Next, the process proceeds to step S3, where the detected vehicle speed value V of the vehicle speed sensor 26 is read.
The process moves to a preset ultrasonic distance measuring device 27FL and 27FR and the front wheels 11FL and the distance L _U between 11FR is divided by the vehicle speed detecting value V ultrasonic distance measuring device 27FL and 27FR
The detected road surface with the front wheels 11FL and 11FR to calculate the delay time tau _DF until the passage in the front wheels to the distance L _U 11FL, 11FR and the rear wheels 11RL, a value obtained by adding the wheelbase L representing the 11RR distance ( L _U + L) is divided by the vehicle speed detection value V to calculate a delay time τ _DR required for the rear wheels 11RL and 11RR to pass through the road surface detected by the ultrasonic distance measuring devices 27FL and 27FR.

Then, the process proceeds to step S5, in which the delay times τ _DF and τ _DR calculated in step S4 are divided by the sampling time T _S to obtain the front wheels 11FL and 11FR at the present time.
And a shift address corresponding to the road surface information on which the rear wheels 11RL and 11RR pass, and the storage device 62 is determined based on the shift address.
to access the corresponding front wheel road surface information H _GFL (n), H
_{The GFR} (n) and the rear wheel road surface information _HGRL (n) _{and HGRR} (n) are read.

Next, the process proceeds to step S6, where
By performing the calculations of equations (1) to (4), each pressure control valve 20FL
Calculate pressure command values P _{FL to} P _RR for 20 _RR . P _FL = P _N + K _F · H _GFL (n) ……… (1) P _FR = P _N + K _F · H _GFR (n) ……… (2) P _RL = P _N + K _R · H _GRL (n) ……… (3) P _RR = P _N + K _R · H _GRR (n) ……… (4) where H _N is to maintain the vehicle height at a preset target vehicle height. , The neutral pressure command values K _F and K _R necessary for the front wheel side and the rear wheel side are set in advance.

Then, the process proceeds to step S7, in which the pressure command values P _FL -P _RR calculated in step S6 are output to the output side interface circuit 62b and the D / A converters 63FL-6.
After outputting to the drive circuits 64FL to 64FR via 3RR, the timer interrupt process is terminated and the process returns to the predetermined main program. Therefore, it is assumed that the vehicle is traveling at a constant speed on a flat good road while maintaining the target vehicle height. In this state,
Because the vehicle maintains the target height on a flat good road,
The distance measurement values H _FL and H _FR of the ultrasonic distance measuring devices 27 _FL and 27 _FR substantially coincide with the target vehicle height H _T , and these are input to the road surface information correction circuit 29.

On the other hand, the swinging of the vehicle body side member 10 does not occur.
The vertical acceleration sensors 28FL arranged in front and back and
28RL acceleration detection value Z_GFLAnd Z_GRLBecomes almost zero
These are input to the road surface information correction circuit 29. This
Therefore, in the road surface information correction circuit 29, the ultrasonic distance measuring device
27FL and 27FR distance measurement H_FLAnd H_FRIs the second derivative
The acceleration H is differentiated by the second order in the circuits 41FL and 41FR._FL″
And H_FR”, But the distance measurement H_FLAnd H_FRStands for
Constant value H_T, The acceleration H_FL″ And H
_FR″ Is substantially zero and the vertical acceleration detection value Z before and after
_GFLAnd Z_GRLIs substantially zero, the correction value calculation circuit 42
Bounce outputs from the divider circuits 42b and 42d
Speed G_BAnd pitching acceleration G _PAlso become zero
Correction value H_AIs also zero, and eventually the subtractor 43FL and
Corrected road surface information H output from 43FR_GFLAnd H_GFRAlso
It becomes zero, and these are passed through A / D converters 61FL and 61FR.
Is input to the microcomputer 62.

As described above, in the state where the vehicle is traveling on a flat good road, the microcomputer 62 executes the process of FIG. 5 every predetermined sampling time T _S ,
Since the zero corrected road surface information H _{GFL and HGFR} are sequentially stored in the shift register area of the storage device 62d, step S
The front wheel side corrected road surface information H _GFL (n), H _GFR (n) read out in step 5
And the rear wheel side corrected road surface information H _GRL (n), H _GRR (n) becomes zero, and each of the pressure control valves 20FL to
The pressure command values P _{FL to} P _{RR for 20 RR} are calculated according to the equations (1) to
In the equation (4), the second term on the right-hand side becomes zero so that the neutral pressure command value P _{N is obtained} .
And a driving circuit 64 via D / A converters 63FL to 63RR
Output to FL to 64RR.

Therefore, the driving circuits 64FL to 64RR are neutral.
Pressure command value P_NPressure command value P_FL~ P _RRIs the neutral current i_Nphase
Command current i_FLAnd i_FRIs converted to front wheel pressure control.
It is supplied to the control valves 20FL to 20RR. This results in pressure control
Neutral pressure P from valve 20FL-20RR_NControl pressure P_CIs the front wheel side
Output to the hydraulic cylinders 18FL-18RR of
The vehicle body side member 10 and the wheel side portion by the cylinders 18FL to 18RR
Generates thrust to maintain stroke between materials 14 at target vehicle height
I do.

When the ultrasonic distance measuring devices 27FL and 27FR pass through a transient portion such as a seam on a concrete pavement road from this good road running condition, the distance measurement value H is obtained by passing the convex portion. _FL and H _FR is as shown in FIG. 6 (a), the target vehicle height at the end t _E increases after temporarily sharply in response to the convex shape from the target vehicle height H _T from the start t _S It will return. Therefore, the accelerations H _FL ″ and H _FR ″ calculated by the second-order differentiating circuits 41FL and 41FR of the front wheel side road surface information correcting circuit 29F change from zero to a negative direction at time t _S as shown in FIG. 6B. After increasing, it decreases and returns to zero at time t _T, which is the vertex position of the convex portion, and then increases in the positive direction, decreases and returns to zero at time t _E. At this time, since the body does not change posture, the acceleration detection values Z _GFL and Z _{GFL of} the front and rear vertical acceleration sensors 28FL and 28RL are determined.
_GRL maintains zero, and the correction value H _A calculated by the correction value calculation circuit 42 of the road surface information correction circuit 29 also continues to be zero. Therefore, the acceleration H _FL ″ output from the second-order differentiation circuits 41FL and 41FR. and H _FR "is directly input to the microcomputer 62 as the correction road information H _GFL and H _GFR.

For this reason, the microcomputer 62
Sampling time T during which the processing of step 5 is executed_SEach time, FIG.
(b) Corrected road surface information H corresponding to the road surface convex shape shown in FIG._GFLPassing
And H _GFRAre sequentially shifted while shifting the storage device 62d.
Is stored in the register area. Therefore, FIG.
As shown, the front wheel side is calculated in step S4 of FIG.
Issued front wheel side delay time τ_DFTime t has elapsed_F1From
Next, delay time τ_DFJust before, that is, the time t described above._SCorrection road
Surface information H_GFLAnd H_GFRSubsequent corrected road surface information H _GFLas well as
H_GFRIs read (step S5), and the corrected road surface information is read.
H_GFLAnd H_{GF R}Based on the above formulas (1) and (2)
The front wheel side pressure command value P _FLAnd P_FRIs calculated
(Step S6), these are connected to the pressure control valve 20FL and
Output to 20FR. As a result, the time t_F1To front wheel side pressure
Command value P_FL, P_FRIs the neutral pressure command value P_NTo decrease from
Command output from the drive circuits 64FL and 64FR
Current i_FLAnd i_FRIs the neutral current i_NLower, which
Control pressure output from the pressure control valves 20FL and 20FR
P_CIs neutral pressure P_CNThe hydraulic cylinder 18FL and
And 18FR thrust are reduced, reducing the front wheel stroke.
By reducing the number of front wheels 11FL and 11FR
The upward and downward direction generated on the vehicle body side member 10 by raising
Acceleration can be suppressed.

Thereafter, at time t _F2 , the pressure command values P _FL and P _{FL
After FR} has returned to the one end the neutral pressure command values P _N, increased by increasing from the neutral pressure command values P _N, contrary to the above, the thrust of the hydraulic cylinders 18FL and 18FR is raised, the front wheel side stroke The front wheels 11FL and 11FL
It is possible to suppress the vertical acceleration in the downward direction generated on the vehicle body-side member 10 after the FR has passed through the convex top.

Similarly, the rear wheel side is shown in FIG.
As described above, the rear wheel side delay calculated in step S4 of FIG.
Time τ_DRTime t has elapsed_R1From the delay time τ_DRIs
Before, ie, at the time t described above._SCorrected road surface information H_GFLAnd H
_GFRSubsequent corrected road surface information H_{GF L}And H_GFRRead out (scan
Step S5), these corrected road surface information H_GFLAnd H_GFRTo
By performing the calculations of the above equations (3) and (4) based on
Front wheel pressure command value P_RLAnd P_RRIs calculated (step S
6) Output these to the pressure control valves 20RL and 20RR.
You. As a result, the time t_R1From the rear wheel pressure command value P_RL, P
_RRIs the neutral pressure command value P _NDrive time by decreasing from
Command current i output from paths 64RL and 64RR_RLAnd i
_RRIs the neutral current i_NLower, thereby reducing the pressure control valve
Control pressure P output from 20RL and 20RR_CIs neutral pressure P
_CNThe thrust of the hydraulic cylinders 18RL and 18RR
To reduce the rear-wheel stroke.
From the rear wheels 11RL and 11RR
Suppress the upward and downward acceleration in the body-side member 10
At time t_R2The vehicle body side member 10
The vertical acceleration in the downward direction
You.

In this way, the front and rear wheel strikes
Rook is detected by the convex part of the ultrasonic distance measuring instruments 27FL and 27FR
According to the relative acceleration between the road surface and the vehicle body, the value of which is second-order differentiated
The vertical direction generated in the vehicle body side member 10 by controlling
The acceleration can be suppressed, but this front wheel side and rear wheel
Reaction at the end of the side stroke control
Pitching motion may occur in the side member 10, and this
For example, the pitching motion lifts the front wheel side,
When the rear wheel side sinks, the vertical acceleration on the front wheel side
Vertical acceleration detection value Z of sensor 28FL_GFLIncreases in the positive direction
The vertical acceleration of the rear wheel vertical acceleration sensor 28RL.
Detection value Z_GRLIncreases in the negative direction, the correction value
The addition output of the adder 42a of the arithmetic circuit 42 maintains zero.
However, the subtraction output of the subtractor 42c is positive,
Positive pitching acceleration G from d_PIs output.
At the position of the ultrasonic distance measuring device 27FL and 27FR with the exchanger 42e
Is converted to the pitching acceleration of
Bounce acceleration G_B, The correction value H_AIs
Pitching acceleration G_PIt becomes a positive value according to only this. Soshi
The correction value H_ASupplied to the subtractors 43FL and 43FR
Therefore, the vehicle and road are subtracted by these subtractors 43FL and 43FR.
Relative acceleration H to the surface_FL″ And H_FRFrom the correction value H _AIs reduced
And is affected by the pitching motion of the vehicle.
The distance measurement of the ultrasonic distance measuring instruments 27FL and 27FR to the ground.
Outgoing price H_FLAnd H_FRDifferential circuit 4 due to the increase of
Relative acceleration H output from 1FL and 41FR_FL″ And H
_FR″ Increase can be offset.

Similarly, when a bouncing motion of the vehicle body occurs on the vehicle body side member 10 due to the reaction generated at the end of the stroke control on the front wheel side and the rear wheel side, and the front wheel and the rear wheel side are both sunk, the vertical acceleration sensor 28FL and the vertical acceleration sensor 28FL Both the vertical acceleration detection values Z _GFL and Z _{GRL of the} 28RL become negative values, and accordingly, the addition output of the adder 42a of the correction value calculation circuit 42 becomes a negative value, and conversely, the subtraction output of the subtractor 42c becomes zero. since the bounce acceleration G _B from the adder 42f
_A positive correction value _HA is output based on the relative acceleration H of the second-order differentiating circuits 41FL and 41FR due to the bouncing motion of the vehicle body.
The decrease in _FL "and _HFR " can be offset.

Further, when a bouncing motion and a pitching motion occur in the vehicle body on the vehicle body side member 10 due to a reaction generated at the end of the stroke control on the front wheel side and the rear wheel side,
From division circuit 42b and 42d of the correction value calculating circuit 42 respectively bounce acceleration G _B and pitching acceleration G _P is output, for these pitching acceleration G _P of an ultrasonic distance measuring device 27FL and 27FR position conversion circuit 42e is After being converted to pitching acceleration, the two are added to calculate a correction value _HA, which is then subtracted by subtractors 43FL and 43FR.
, The fluctuations due to the bounce motion and the pitching motion included in the relative accelerations H _FL ″ and H _FR ″ output from the second-order differentiating circuits 41 _FL and 41 _FR can be canceled.

As described above, the road surface information correction circuit 29 generates the relative accelerations H _FL ″ and H _FR ″ based on the ground distance detection values H _FL and H _FR detected by the ultrasonic distance measuring devices 27FL and 27FR on the vehicle body. Since the fluctuations due to the effects of the bounce motion and the pitching motion can be offset, accurate road surface information can be input to the controller 30, and the control accuracy of the hydraulic cylinders 18FL to 18RR can be improved.

When the ultrasonic distance measuring devices 27FL and 27FR pass through a concave portion extending in the width direction of the road, such as a step, in the above-described good road traveling state, the ultrasonic distance measuring device changes according to the shape of the concave portion. The ground distance measurement values H _FL and H _FR of 27FL and 27FR increase, and the relative accelerations H _FL ″ and H _FR ″ output from the second-order differentiation circuits 41FL and 41FR of the road surface information correction circuit 29 accordingly increase. because increases in the positive direction, at the time of the lapse of the delay time tau _DF and tau _DR from this point, respectively the front wheels 11FL, 11FR and the rear wheels 11RL,
11RR hydraulic cylinders 18FL, 18FR and 18RL, 18
The thrust of the RR is increased, the stroke between the vehicle body-side member 10 and the wheel-side member 14 becomes longer, and the downward vertical acceleration generated in the vehicle body-side member 10 due to the depression of the recess can be suppressed.

As described above, according to the above-described embodiment, when one or both of the ultrasonic distance measuring devices 27FL and 27FR pass through the temporary unevenness in a good road running state, the unevenness is applied to the front wheels 11FL and 27FL. when 11FR and rear wheels 11RL and 11RR passes, occurs on the vehicle body in the front wheel side and rear wheel side delays the forward road information based on the ultrasonic distance measuring device 27FL and 27FR of the ground distance measurement values H _FL and H _FR The control signal for suppressing the acceleration is formed, and the road surface information correction circuit 29 corrects the fluctuation of the front road surface information due to the bouncing motion and the pitching motion of the vehicle body. Without receiving
High-precision suspension control can be performed.

In the first embodiment, the ultrasonic distance measuring devices 27FL and 27FL are used as the front road surface information detecting means.
Although the case where 7FR is applied has been described, instead of this, an ultrasonic transmitter and a receiver are simply provided, and these are connected to the microcomputer 62, so that the measured value of the ground distance is calculated by the microcomputer 62. Alternatively, a laser distance meter or another non-contact distance measuring device may be applied instead of the ultrasonic distance measuring devices 27FL and 27FR.

Next, a second embodiment of the present invention will be described with reference to FIG. In the second embodiment, suspension control similar to that of a normal active suspension is performed on the front wheel side based on the detected value of vertical acceleration, and suspension control is performed on the rear wheel side using front wheel motion information as front road surface information. It was made.

That is, in the second embodiment, as shown in FIG. 7, vertical acceleration sensors 28FL and 28FR are provided as front road surface information detecting means provided on the vehicle body corresponding to the front wheels 11FL and 11FR. Vertical acceleration detection value Z _{GFL of the} direction acceleration sensors 28FL and 28FR
And Z _GFR are supplied to a road surface information correction circuit 29R corresponding to the road surface information correction circuit 29 described above.

This road surface information correction circuit 29R is shown in FIG.
The front and rear vertical acceleration sensors 28FL and 28FL
RL acceleration detection value Z_GFLAnd Z_GRLAre entered and these
Based on bouncing and pitching movements
Value H_AAnd a correction value calculation circuit 44 for calculating
Acceleration detection value Z of the direction acceleration sensors 28FL and 28FR
_GFLAnd Z_GFRFrom the correction value H_ASubtractor 45RL for subtracting
And 45RR, and these subtracters 45RL and 45RR
Corrected road surface information H output from RR_GFLAnd H_GFRIs A /
Microcomputer via D converter 41RL and 41RR
Input to the data 62.

Here, the correction value calculation circuit 44 adds the vertical acceleration detection values Z _GFL and Z _GRL similar to the above-described correction value calculation circuit 42, and divides the added output by “2”. split to calculate the dividing circuit 44b for calculating the bounce acceleration G _B, a subtracter 44c for subtracting the Z _GRL from vertical acceleration detected values Z _GFL, the pitching acceleration G _P is divided by the subtraction output "2" Te a calculation circuit 44d, division circuit 44b and a band-pass filter 44e and 44f which bounce acceleration G _B and pitching acceleration G _P is supplied separately output from 44d, the correction value this by adding these filter outputs And an adder 44g that outputs _HA . Here, the band-pass filter 44e, passes only the frequency region of the bouncing resonance frequency f _B vicinity, as shown in FIG. 8 (a), the band-pass filter 44f, the pitching resonance frequency as shown in FIG. 8 (b) It is set so that only the frequency region near f _P is passed.

In the microcomputer 62,
In the process of No. 5, in step S4, the front wheel delay time τ_DF
Is set to zero, that is, the present time, and the rear wheel delay time τ_DRThe
Calculating by dividing the wheel base L by the vehicle speed detection value V
Except for this, the same processing as in FIG. 5 is performed. According to the second embodiment,
Then, for the front wheel side, the time when the process of FIG. 5 is started
Road surface information H at_GFLAnd H_GFRBased on the (1)
Equation (2)_FLAnd P_FRBut
Calculated on the rear wheel side._DRJust before
Corrected road surface information H at a point_GRL(n) and H_GRR(n)
Then, the rear wheel side pressure command value is calculated according to the above formulas (3) and (4).
P_RLAnd P_RRAre calculated, and these pressure command values P_FL~ P_RR
Is the output side interface 62b and the D / A converter 63FL
Output to the drive circuits 64FL to 64RR through
Therefore, as in the first embodiment described above, it is possible to adapt
Acceleration that occurs in the vehicle body
The bounce movement and the
Even if a ching motion occurs, the road surface information correction circuit 29R
Of the bounce acceleration G_BAnd pick
Ching acceleration G_PIs calculated, and these are added to obtain a correction value H
_AAnd the correction value H _AIs the vertical acceleration detection value Z
_GFLAnd Z_GFRFrom the first embodiment.
Like bounce and pitching movements
Accurate road surface information can be obtained. Moreover,
In the second embodiment, the division circuit 4 of the correction value calculation circuit 44
Bounce acceleration G output from 4b and 44d_Bas well as
Pitching acceleration G_PAre bandpass filters 44e, respectively.
And 44f, and these band pass filters 44
Bounce resonance frequency f at e and 44f_BAnd pitching
Resonance frequency f_PSince only the nearby frequency domain is passed,
More accurate road surface information can be detected.

In the second embodiment, the case where the vertical acceleration sensors 28FL and 28FR are applied as the front road surface information detecting means has been described. However, the present invention is not limited to this. A stroke sensor that detects a change in stroke may be applied. In each of the above embodiments, the case where the road surface information correction circuits 29 and 29R are configured by analog circuits has been described. However, the present invention is not limited to this, and the microcomputer may perform arithmetic processing. Instead of electrically correcting the road surface information, the forward road surface information detecting means may be mechanically displaced to offset the fluctuation due to the bounce motion and the pitching motion.

Further, in each of the above embodiments, the case where the suspension control is performed only based on the vertical acceleration has been described. However, the present invention is not limited to this.
Control signals for suppressing roll, pitch, and bounce are calculated based on acceleration detection values of other lateral acceleration sensors, longitudinal acceleration sensors, and the like, and these are referred to as the pressure command values P _{FL to} P _FL.
Total control may be performed by adding or subtracting from _RR .

Furthermore, in the above-described embodiment, the case where the front and rear vertical acceleration sensors 28FL and 28FR are arranged on the left side of the vehicle body side member 10 has been described. May be arranged at a diagonal position sandwiching the position of the center of gravity. Further, in the above-described embodiment, the case where the pressure control valves 20FL to 20RR are applied as the control valve has been described. However, the present invention is not limited to this, and another flow control type servo valve or the like can be applied. .

Further, in the above-described embodiment, the case where the controller 30 is constituted by the microcomputer 62 has been described. However, the present invention is not limited to this, and the controller 30 may be constituted by combining electronic circuits such as a shift register and an arithmetic circuit. Needless to say, this may be done. Furthermore, in the above-described embodiment, the case where the working oil is used as the working fluid has been described. However, the working fluid is not limited to this, and any working fluid may be used as long as the fluid has a low compression ratio.

As described above, according to the suspension control apparatus of the present invention, the front road surface information detecting means
The road surface information at the position in front of the wheel to be controlled is
Thereby detected by vibration to the vehicle body of the front and rear wheels
The acceleration information generated in the vehicle body is detected by the vibration information detecting means,
The road surface information correction means uses acceleration information from the excitation information detection means .
Calculate the acceleration occurring in the front road surface information detecting means from the
Since the front road surface information of the front road surface information detecting means is corrected based on the calculated acceleration value , the front road surface information of the front road surface information detecting means includes a fluctuation amount due to a swing such as a bouncing motion and a pitching motion of the vehicle body. Is included, accurate road surface information from which this variation has been removed can be detected accurately, and an effect that high-precision suspension control can be performed can be obtained.

[Brief description of the drawings]

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

FIG. 2 is a characteristic diagram showing a relationship between a control current and a command current of a pressure control valve.

FIG. 3 is a characteristic diagram showing output characteristics of a vertical acceleration sensor.

FIG. 4 is a block diagram illustrating an example of a controller.

FIG. 5 is a flowchart illustrating an example of a processing procedure of a microcomputer.

FIG. 6 is a time chart for explaining the operation of the first embodiment;

FIG. 7 is a block diagram illustrating a road surface information correction circuit according to a second embodiment of the present invention.

FIG. 8 is a characteristic diagram of the band-pass filter, and FIG.
(a) is a frequency characteristic diagram of the band-pass filter 44e, FIG.
(b) is a frequency characteristic diagram of the bandpass filter 44f.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Body member 11FL-11RR Wheel 14 Wheel member 18FL-18RR Hydraulic cylinder 20FL-20RR Pressure control valve 22 Hydraulic source 26 Vehicle speed sensor 27FL, 27FR Ultrasonic distance measuring device 28FL, 28FR, 28RL Vertical acceleration sensor 29, 29R Road surface Information correction circuit 30 Controller 42, 44 Correction value calculation circuit 62 Microcomputer

Continuation of the front page (56) References JP-A-61-135811 (JP, A) JP-A-60-193710 (JP, A) JP-A-60-142207 (JP, A) JP-A-4-100713 (JP) , A) (58) Field surveyed (Int. Cl. ⁷ , DB name) B60G 23/00

Claims (3)

(57) [Claims] An actuator disposed between a wheel and a vehicle body for generating a control force capable of controlling a stroke between the wheel and the vehicle body according to a control signal, and a front for detecting road surface information ahead of the wheel as acceleration. and the road surface information detection unit, the suspension control apparatus and a control means for controlling the actuator based on the forward road information of the previous <br/> lateral road surface information detection means, the vibration to the vehicle body of the front and rear wheels
A vibration information detecting means for detecting acceleration information generated in the vehicle body, the front road from the acceleration information of the pressurized vibration information detecting means
Calculating an acceleration occurring in the information detecting unit, a suspension control device characterized by comprising a road information correcting means for correcting the forward road surface information of the forward road surface information detection means on the basis of the acceleration calculated value <br/> . 2. The front road surface information detecting means includes:
Of the second derivative of the distance between the vehicle body and the road surface with respect to time
And the detected value is used as forward road surface information.
The suspension control according to claim 1, wherein
apparatus. 3. The front road surface information detecting means is provided on a front wheel.
The acceleration of the vehicle is detected, and the detected value
Control the actuator on the rear wheel side as information.
The suspension according to claim 1, wherein the suspension is configured as follows.
Pension control device.