JP3100772B2 - Vehicle suspension 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 apparatus for a vehicle that controls the supply and discharge of a fluid to a fluid cylinder to vary suspension characteristics.

[0002]

2. Description of the Related Art Conventionally, as a vehicle suspension device, for example, as disclosed in Japanese Patent Application Laid-Open No. 3-182826, a fluid cylinder is disposed between a vehicle body and each wheel. A so-called active control suspension device (ACS device) is known, in which the flow rate of the vehicle is independently controlled by a flow control valve for each wheel to vary the suspension characteristics of the vehicle according to the driving state.

In this conventional example, a vehicle height signal and a vertical acceleration signal are collected for each wheel, these signals are passed through a low-pass filter, and a bounce component, a pitch component, and a roll component of vehicle displacement are extracted from the low-pass component. Thus, a flow control signal to the fluid cylinder for suppressing the fluctuation of the vehicle body posture in each of the bounce mode, the pitch mode, and the roll mode is calculated. The conventional suspension apparatus further includes, as parameter signals for active control of the suspension, other than the above-described vehicle height signal and vertical acceleration (hereinafter, acceleration is abbreviated as G) signal,
A lateral acceleration signal is input, and a flow control signal to the fluid cylinder is calculated to suppress yaw motion of the vehicle body.

[0004]

In the above conventional example, the lateral G signal is used in addition to the vehicle height signal and the vertical G signal, particularly because the transient roll motion of the vehicle body is caused by vibration transmitted from the wheels. The reason for this is to determine whether it is due to vibration transmitted from the vehicle body during the turn. That is, the roll of the vehicle body occurs even when some of the wheels move up and down, or even when the vehicle turns. But,
Since the lateral G signal is generated only when the vehicle body turns, when the lateral G signal is generated, it indicates that the vehicle is turning, and the suspension control for roll suppression by the vertical G signal is turning. Conversely, when the lateral G signal is not generated, the roll control based on the upper and lower G signals is strongly used to suppress the roll, so that the roll is suppressed even when turning or not turning. This is because control can be reliably performed.

However, the inventors of the present application have noted that, as described above, the active suspension control does not always succeed in controlling the roll even if the lateral G signal is taken into consideration. Found to be due to ingredients. However, simply removing the high-frequency components of the upper and lower G signals makes it impossible to perform the suppression control on the vehicle body motion that should originally occur in the high-frequency property.

The present invention has been made in view of such a point, and it is an object of the present invention that a horizontal G signal rarely contains a high frequency component originally, and if it is included, it is not originally suppressed. Focusing on the fact that this is the result of unreliable vehicle motion, the effect of removing the high-frequency components of the upper and lower G signals is eliminated, and the control to suppress the originally generated high-frequency vehicle vibration is emphasized on the horizontal G signal. It is an object of the present invention to provide a vehicle suspension device that performs the above-described suspension control.

[0007]

In order to achieve the above object, the present invention, as shown in FIG. 1, controls the supply and discharge of a fluid to and from a fluid cylinder disposed between a vehicle body and each wheel. In the suspension device for a vehicle, the characteristics of the suspension of which can be changed, a sensor means for detecting a vertical acceleration signal of the vehicle body, a sensor means for detecting a lateral acceleration signal of the vehicle body, and each of the two detected signals Low-pass filter means for separately blocking high-frequency components; and control means for controlling supply and discharge of a flow rate to and from the fluid cylinder using the two signals output from the low-pass filter means as parameters, wherein the low-pass filter means The cutoff frequency for the vertical acceleration signal set in Suspension device for a vehicle, characterized in that set to be lower than off frequency.

[0008]

The oscillation of suspension control can be prevented by making the contribution of the upper and lower G signals having a high frequency fluctuation component relatively lower than the contribution of the horizontal G signal having a low frequency fluctuation. In addition, since the high-frequency gain of the horizontal G signal is increased by an amount corresponding to the cut of the high frequency of the upper and lower G signals, the roll phenomenon that occurs transiently is effectively prevented.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. 2 shows a vehicle suspension system according to an embodiment of the present invention, FIG. 3 shows a hydraulic circuit diagram of the suspension system of FIG. 2, and FIGS. 4 to 6 show control modes of the suspension system of FIG. FIG. <Outline of Embodiment> The features of this embodiment are as follows: I: The signal from the vehicle height sensor is passed through an extremely low-frequency low-pass filter in order to improve driving stability. This suppresses the control oscillation phenomenon that easily occurs with high-frequency vehicle body fluctuations.

II: In view of the fact that roll control has a great effect on the controllability, the roll cutoff frequency is set higher than the bounce or pitch cutoff frequency to enhance the responsiveness of the roll control and make the transient. Prevent rolls. III: By reducing the contribution of the relative high-frequency component of the vertical acceleration (hereinafter, acceleration is abbreviated as G) signal to the suspension control and increasing the contribution of the relative high-frequency component of the lateral G signal accordingly. The purpose of the present invention is to prevent the occurrence of transitional roll motion, and also to prevent oscillation of suspension control. . <Structure of Suspension Apparatus> A suspension apparatus according to an embodiment having such features will be described first with reference to FIG.

In FIG. 2, 1 is a vehicle body, 2 _F is a front wheel, 2 _R
It is a rear wheel, between the vehicle body 1 and the front wheel 2 _F and the vehicle body 1
And between the rear wheel 2 _R, each fluid cylinder 3 is arranged. Each of the fluid cylinders 3 has a fluid chamber 3c defined by a piston 3b fitted into the cylinder body 3a. The upper end of the rod 3d coupled to the piston 3b is connected to the vehicle body 1, the cylinder body 3a each wheel 2 _F,
2 _R

The fluid chamber 3c of each of the fluid cylinders 3 has:
The gas springs 5 are connected to each other through the communication passages 4. Each of the gas springs 5 is divided into a gas chamber 5f and a hydraulic chamber 5g by a diaphragm 5e, and the hydraulic chamber 5g communicates with a hydraulic chamber 3c of the fluid cylinder 3. Also, 8
Is a hydraulic pump, 9 and 9 are flow rate control valves provided in a hydraulic pressure passage 10 as a high pressure line for communicating the hydraulic pump 8 and each fluid cylinder 3, and the flow rate control valve 9 is 3 has a function of supplying and discharging a fluid (oil) to and adjusting the flow rate.

Further, reference numeral 12 denotes an oil discharge pressure (main pressure) of the hydraulic pump 8 and an accumulator 22a, which will be described later.
The main pressure sensor for detecting the accumulated pressure of 22b, 13 is a cylinder pressure sensor for detecting the hydraulic pressure P of the fluid cylinders 3 for the hydraulic chamber 3c, 14 corresponding to the wheel 2F, 2 _R of the vehicle height (cylinder stroke) vehicle height sensor for detecting the, 15 vertical acceleration sensor for detecting a vertical acceleration of the vehicle (sprung acceleration of the wheels 2F, 2 _R), 16 is a lateral acceleration sensor for detecting a lateral acceleration Y of the vehicle, 17 serving steerable wheels A steering angle sensor 18 for detecting a steering angle of the front wheel 2F, a vehicle speed sensor 18 for detecting a vehicle speed, and detection signals of these sensors 12 to 18 are respectively input to a controller 19 having a CPU or the like therein to obtain a suspension characteristic. Provided for variable control.

Further, reference numeral 110 denotes a warning display unit attached to a front portion of a driver's seat of an instrument panel (not shown). The warning display unit 110 receives a lighting command signal from the controller 19, respectively. A warning lamp A which is lit when various devices of the flow control system fail, and a warning lamp B which is lit when the below-described check valve 38 is closed to stop the supply / discharge control of the flow.

FIG. 3 shows a fluid for each of the fluid cylinders 3.
2 shows a hydraulic circuit for controlling the supply and discharge of the oil. In this figure, the oil
The pressure pump 8 is a variable displacement swash plate piston pump.
Power steering device driven by the drive source 20
It is connected to the hydraulic pump 21 for mounting in two stations. This oil
The high pressure line 10 connected to the pressure pump 8 has three
Accumulators 22a, 22a, 22a communicate at the same location
And at the connection point the hydraulic passage 10
Front wheel side passage 10F and rear wheel side passage 10_RAnd branched to
You. Further, the front wheel side passage 10F is connected to the left front wheel side passage 10F._FLWhen
Right front wheel side passage 10 _FRAnd each of the passages 10_FL, 1
0_FRIs the fluid cylinder 3 of the corresponding wheel_FL, 3_FRHydraulic pressure
The chamber 3c is connected. On the other hand, the rear wheel side passage 10_RTo
If one accumulator 22b is connected in communication
In the downstream side, the left rear wheel side passage 10_RLAnd right rear wheel side passage
10_RRAnd each of the passages 10_RL, 10_RRCorresponds to
Wheel fluid cylinder 3_RL, 3_RRHydraulic chamber 3c communicates
Have been.

Each of the above fluid cylinders 3 _FL , 3 _FR , 3 _RL , 3
Gas connected to _RR spring _{5 FL, 5 FR, 5 RL} , 5 RR , respectively, specifically provided by a plurality (four in the figure), these gas springs 5a, 5b, 5c, 5d is The fluid pressure chambers 3c of the corresponding fluid cylinders 3 are connected to each other in parallel via the communication path 4. Further, the gas springs 5a to 5d
Are provided with orifices 25 interposed at the branch portions of the communication passages 4 so as to exhibit both a damping action at each of the orifices 25 and a buffer action for the gas sealed in the gas chamber 5f. ing. In the communication passage 4 between the first gas spring 5a and the second gas spring 5b, a damping force switching valve portion 26 for adjusting the passage area of the communication passage 4 is provided. 26 is an open position for opening the communication passage 4;
It has two positions, a throttle position that significantly reduces the passage area.

In the hydraulic passage 10, an unload valve 27 and a flow control valve 28 are provided upstream of the accumulator 22a.
And are connected. The unload valve 27 is configured to introduce the pressure oil discharged from the hydraulic pump 8 into the swash plate operating cylinder 8a of the hydraulic pump 8 to reduce the oil discharge amount of the hydraulic pump 8, A discharge position for discharging pressurized oil, and when the oil discharge pressure of the hydraulic pump 8 exceeds a predetermined upper limit oil discharge pressure (about 160 kgf / cm2), the state is switched from the discharge position to the introduction position. And is maintained so as to be equal to or lower than the lower limit discharge pressure (about 120 kgf / cm2) of the hydraulic pump 8. The oil discharge pressure of the hydraulic pump 8 is set within a predetermined pressure setting range (120 to 160 kgf / cm2).
It has a function as a pressure regulating valve for holding control.
The flow control valve 28 is configured to introduce the hydraulic pressure from the hydraulic pump 8 to the swash plate operating cylinder 8a of the hydraulic pump 8 via the unload valve 27, and to control the hydraulic pressure in the cylinder 8a to the unload valve 27. And a discharge position for discharging the hydraulic pressure from the hydraulic pump 8 to the reserve tank 29 when the oil discharge pressure of the hydraulic pump 8 is maintained within a predetermined pressure setting range by the unload valve 27. And has a function of keeping the differential pressure between the upstream and downstream of the hydraulic pump 8 constant and controlling the oil discharge amount of the hydraulic pump 8 to be constant. The supply of oil to each fluid cylinder 3 is performed by accumulators 22a and 22b.
It is performed with the accumulation pressure of. The accumulator 22
The accumulated pressures a and 22b are substantially equal to the pressure at the portion of the hydraulic passage 10 downstream of the accumulator as the main passage, and this accumulated pressure is referred to as the main pressure.

On the other hand, the accumulator 22 in the hydraulic passage 10
Downstream a, four flow control valves 9, 9, ... are provided corresponding to the four wheels of the vehicle. Hereinafter, since the configuration of the portion corresponding to each wheel is the same, only the left front wheel side will be described, and the description of the other will be omitted. That is, the flow control valve 9 includes the inflow valve 35 and the discharge valve 37. The inflow valve 35
Has two positions, a closed position and a fluid supply position (open position) with a variable opening, and has a left front wheel side passage 10 of the hydraulic passage 10.
Have been interposed _FL, and supplies to the subtle (micro) fluid cylinders 3 _FL fluid accumulated in the accumulator 22a to the fluid supply position from the left front wheel side passage 10 _FL by opening and closing operation. The discharge valve 37 has two positions, a closed position and a fluid discharge position (open position) with a variable opening.
The left front wheel side passage 10 _FL is interposed in a low pressure line 36 that connects to the reserve tank 29, and the fluid supplied to the fluid cylinder 3 _FL is reserved through the low pressure line 36 at the fluid discharge position due to the minute opening and closing operation. It is discharged to the tank 29. Each of the inflow valve 35 and the discharge valve 37 is a spool type, and has a built-in differential pressure valve that maintains the pressure of the fluid at a predetermined value at the open position.

The inflow valve 35 and the fluid cylinder 3 _FL
The left front wheel side passage 10 _FL check valve 38 of the pilot圧応Dogata as poppet shutoff valve is interposed between the. The check valve 38 is controlled by a pilot line 39 so that the hydraulic pressure (ie, the main pressure or the accumulators 22a and 22b) in the hydraulic passage 10 upstream of the inflow valve 35 is
(Accumulated pressure) is introduced as a pilot pressure, and is provided so as to close when the pilot pressure is 70 kgf / cm2 or less. That is, only when the main pressure is 70 kgf / cm2 or more, the supply of the pressure oil to the fluid cylinder 3 and the discharge of the oil in the fluid cylinder 3 become possible.

Further, reference numeral 41 denotes a fail-safe valve provided in a communication passage 42 which connects the downstream side of the accumulator 22a of the hydraulic pressure passage 10 and the low-pressure line 36. The fail-safe valve 41 is switched to the open position in the event of a failure and is switched to the open position. It has a function of returning the oil storage of 22b to the reserve tank 29 and releasing the high pressure state. Reference numeral 43 denotes a throttle provided in the pilot line 39, which has a function of delaying the closing of the check valve 38 when the fail-safe valve 41 is opened. 44 is a relief valve to return the opening operation to the oil when the oil pressure of the front wheel side of each fluid cylinder 3 _FL, 3 _FR the hydraulic chamber 3c rises abnormally in the low pressure line 36. Reference numeral 45 denotes a return accumulator connected to the low-pressure line 36, which performs a pressure accumulating operation when oil is discharged from the fluid cylinder 3. <Structure of Controller 19> Next, control of the flow rate to each fluid cylinder 3 by the controller 19 will be described with reference to FIGS.

FIG. 4 illustrates the generation logic of the control signal Q for controlling the flow rate of the controller 19 to the cylinder 3. As shown in the figure, the flow control by the controller 19 includes a vehicle height control system A, a vehicle height displacement suppression system B, a vertical acceleration suppression system C, a torsion suppression system D, and a roll control correction system E. Each system is
Flow control signals Q1, Q2, Q for cylinders of each wheel
3, Q4, Q5, and control signals Q1, Q2, Q3, Q4, Q5 generated by these systems,
The individual wheels are combined with each other to generate control signals (Q _FR , Q _FL , _QR R, _{QR L} ) for the wheels.

The outline of control in each control system will be described. In the vehicle height control system A, the calculation units 100 _B , 10
0 _P and 100 _R are generated by calculating a bounce component, a pitch component, and a roll component from the four vehicle height signals X from the four vehicle height sensors 14 for the respective wheels.
_B , 101 _P and 101 _R calculate the flow control signals for the respective components. The calculated flow control signals for the three components are combined for each wheel, and Q _FR1 , Q _FL1 , Q _RR1 ,
Output as _QRL1 .

In the vehicle height displacement suppression system B, the differentiator 10
2 differentiates the four vehicle height signals and calculates the operation units 103 _P , 10
3 _R extracts the pitch component and the roll component of the differential signal, calculation unit 104 _P, 104 _R is calculating the flow rate control signal for each of the pitch component and the roll component. The calculated flow control signals for the two components are combined for each wheel and output as Q _FR2 , Q _FL2 , _QRR2 , and _QRL2 .

In the vertical acceleration suppression system C, the arithmetic unit 1
05 _B , 105 _P and 105 _R are generated by calculating a bounce component, a pitch component and a roll component from signals G from three acceleration sensors provided on the right front wheel, the left front wheel and the rear wheel,
The calculation units 106 _B , 106 _P , and 106 _R calculate the flow control signals for the respective components. The calculated flow control signals for the three components are combined for each wheel, and Q _FR3 , Q _FR
FL3, and is output as Q _RR3, Q _RL3.

In the torsion suppression system, the calculation unit 108 calculates the amount of twist based on the pressure signals P in the four fluid cylinders, and the calculation unit 109 calculates the amount of twist control signals Q _FR4 , Q _FL4 , Q
_RR4 and _QRL4 are calculated for each wheel. In the roll control correction system E, the signal Y from the lateral acceleration sensor is used.
Based on _G , the arithmetic unit 110 controls the control signal Q for each wheel.
_FR5 , _QFL5 , _QRR5 , _QRL5 are calculated and output.

FIG. 4 is a schematic diagram based on FIGS.
The control of the controller 19 will be described in more detail.
You. As described above, the control of the controller 19
Wheel height sensor 14_FR, 14_FL, 14_RR, 14_RLCar height
Displacement signal X_FR, X_FL, X_RR, X_RLTarget vehicle height based on
Obtained from the control system A for controlling the vehicle height and the vehicle height displacement signal
Vehicle high displacement speed signal Y _FR, Y_FL, Y_RR, Y_RLBased on car
Control system B for suppressing high displacement speed and three vertical acceleration cells
Sensor 15_FR, 15_FL, 15_RVertical acceleration signal G_FR, G
_FL, G_RControl system to reduce vertical vibration of vehicle based on vehicle
C and the cylinder pressure sensor 13 for each wheel_FR, 13_FL, 13
_R, 13_RLPressure signal P_FR, P_FL, P_RR, P_RLBased on
Control system D that calculates the torsion of the vehicle body and suppresses the torsion
And the lateral acceleration signal Y of the lateral acceleration degree sensor 16_GBased on
And a control system E for correcting the roll control.
The subscript FR is for the right front wheel, FL is for the left front wheel, and R is
R for right rear wheel, RL for left rear wheel, L for front wheel
R means the rear wheel side.Height control system In the control system A, reference numeral 50 denotes four vehicle height sensors 1.
4_FR, 14_FL, 14_RR, 14_RLHeight displacement signal X_FR, X
_FL, X_RR, X_RLThe output X of the left and right front wheels 2F_FR, X
_FLAnd the left and right rear wheels 2_ROutput X_RR, X_RL
To calculate the bounce component of the vehicle.
It is a minute calculation unit. That is, in the arithmetic unit 50, the bounce component = X_FR+ X_FL+ X_RR+ X_RL Is calculated. 51 is the output of the left and right front wheels 2F.
X_FR, X_FLFrom the sum of the left and right rear wheels 2_RSide output
X_RR, X_RLSubtracting the total value of
This is a pitch component calculation unit for calculating. That is, the arithmetic unit 51 calculates that pitch component = X_FR+ X_FL-X_RR-X_RL Is calculated. 52 is a difference X between the outputs of the left and right front wheels 2F._FR
-X_FLAnd left and right rear wheels 2 _ROutput difference X_RR-X_RLWhen
Is added to calculate the roll component of the vehicle.
It is a calculation. The calculation unit 52 calculates: roll component = X_FR-X_FL+ X_RR-X_RL Is calculated.

Reference numeral 53 denotes the bounce component calculation unit 50
In bounce component of the calculated vehicle and the target average vehicle height T _H
, And calculates a control amount for the flow control piece 9 of each vehicle in the bounce control based on the gain coefficient K _B1 . 54 is a pitch component calculation unit 51
Input the pitch component of the vehicle calculated in
Pitch control unit for calculating a control amount of each flow control valve 9 in the pitch control on the basis of the _P1, likewise 55 inputs the vehicle roll component and the target roll displacement amount T _R calculated by the roll component calculating section 52 , so that the vehicle height corresponding to the target roll displacement amount T _R based on the gain coefficient K _FR1, L _RR1, a roll control section for calculating a control amount of each flow control valve 9 in the roll control.

In order to set the vehicle height to the target vehicle height, each control amount calculated by each of the control units 53, 54, 55 is inverted for each wheel (the vehicle height displacement of the vehicle height sensor 14). After the signal is inverted so as to be opposite to the positive and negative of the signal, the respective control amounts of bounce, pitch, and roll for each wheel are added, and in the control system A, the flow signals Q _FR1 , Q _FL1 , Q _RR1 and _QRL1 are obtained.

That is, for the bounce component, the adder 9
By outputting 0 in which the sign of the control amount calculated by the calculation unit 53 is inverted for all wheels, a control signal that suppresses bounce for each company wheel is output. Further, the adder 91 adds a sign opposite to the addition method in the operation unit 51 to the signal calculated by the operation unit 54 (that is, by adding opposite signs to the front and rear wheels). And outputs a control signal for suppressing pitch movement between them. The adders 92 and 93 add the opposite sign to the control signal calculated by the arithmetic unit 52 to the control signal calculated by the arithmetic unit 55 to the control signal calculated by the arithmetic unit 55, so that the roll between the left and right wheels is adjusted. Is generated.

Arithmetic units 53, 54, 55 and adders 90, 9
1, 92, and 93, respectively, a low-pass filter 8
0_B(For bounce), 80_P(For pitch), 80_RF(front wheel
For rolls), 80_RR(For rear wheel roll)
These low-pass filters are calculated by the calculation units 53, 54 and 55.
The calculated control signal is a preset cutoff frequency X_H1,
X _H2, X_H3, X_H4Control signal is cut off when
And the cutoff frequency X_H1~ X_H4Outputs only the following signals
It is.

FIG. 7 shows a bounce filter 80._B,
Filter 80_PFrequency characteristics (cutoff frequency
X_H1, X_H2= 1 Hz), and FIG.
TA80 _RF, 80_RRFrequency characteristics (cutoff frequency
X_H3, X_H4= 5 Hz).Vehicle height displacement suppression system Next, in the control system B, the vehicle height sensor 14_FR~ 14
_RLHeight displacement signal X from_FR, X_FL, X_RR, X_RLIs it
Differentiator 56_FR, 56_FL, 56_RR, 56_RLEntered
And each differentiator 56_FR~ 56_RLThe vehicle height displacement signal X
_FR, X_FL, X_RR, X_RL, The vehicle height displacement speed
Degree signal Y_FR, Y_RL, Y_RR, Y_RLIs obtained.

The vehicle height displacement speed Y is given by: Y = (X _n −X _n−1 ) / T _Xn : vehicle height displacement at time t X _n−1 : vehicle height displacement at time t−1 T: sampling Required by time.

Further, 57a is the output of the left and right front wheels 2 _F side Y
_FR, the total value of the Y _FL, the right and left rear wheels 2 _R side outputs Y _RR,
By subtracting the total value of the Y _RL, a pitch component arithmetic unit which calculates a pitch component of the vehicle, calculates a pitch component _{= Y FR + Y FL -Y RR} -Y RL of the vehicle height displacement. 57b is a difference Y between the outputs of the left and right front wheels 2F.
And _FR -Y _FL, the output of the right and left rear wheels 2 _R side difference Y _RR -Y _RL
To calculate the roll component of vehicle height displacement = Y _FR −Y _FL + Y _RR −Y _RL . Reference numeral 58 denotes a pitch control unit which inputs the vehicle pitch component calculated by the pitch component calculation unit 57a and calculates a control amount of each flow control valve 9 in pitch control based on the gain coefficient K _p2.
Is a roll control unit that receives the roll component of the vehicle calculated by the roll component calculation unit 57b and calculates the control amount of each flow control valve 9 in roll control based on the gain coefficients K _FR2 and K _RR2 .

The control amounts calculated by the control units 58 and 59 are inverted for each wheel (the differentiator 5).
6 _{FL to} 56 _RL is inverted so as to be opposite to the positive / negative of the vehicle high displacement speed signal), and then the control amounts of the pitch and roll for each wheel are added. flow signal Q _FR2, Q of the valve 9 _FL2, Q _RR2, Q _RL2 is obtained. Vertical acceleration suppression system Next, in the control system C, 60 are three vertical acceleration sensors 15 _FR, 15 _FL, 15 _R of the output G _FR, G _FL, sums the G _R, bounce component of the vertical G = a bounce component arithmetic unit which computes the G _FR + G _FL -G _R. 61 is an output of the three vertical acceleration sensors 15 _FR , 15 _FL , 15 _R
The output G _FR of the right and left front wheels 2F side, the total value of each half value of G _FL, by subtracting the output G _R of the rear wheel 2 _R side, the pitch component of the vertical _{G = 1/2 (G FR} + G FL) a pitch component arithmetic unit which computes the -G _R. Reference numeral 62 denotes a roll component calculation unit that subtracts the output G _FL of the left front wheel from the output G _FR of the right front wheel to calculate a roll component of upper and lower G = G _FR −G _FL .

Reference numeral 63 denotes the bounce component calculation unit 60
The bounce control unit calculates the control amount for the flow control valve 9 of each vehicle in the bounce control based on the gain coefficient _KB3. A pitch control unit that inputs the calculated vehicle pitch component and calculates a control amount of each flow control valve 9 in the pitch control based on the gain coefficient K _P3 . A roll control unit that inputs a roll component and calculates a control amount of each flow control valve 9 in roll control based on gain coefficients K _FR3 and K _RR3 .

Then, the vertical vibration of the vehicle is represented by a bounce component,
Each of the above control units 6 is controlled so as to be pressed by the pitch component and the roll component.
The control amounts calculated in 3, 64 and 65 are obtained by inverting the sign of each wheel, and then bounce each wheel.
The control amounts of the pitch and roll are added, and in the control system C, the flow signals Q _FR3 , Q _FL3 , Q
_RR3, Q _RL3 is obtained.

Operation units 63, 64, 65 and adders 97, 9
Low pass filters between 8, 99 and 110 respectively
85_B(For bounce), 85_P(For pitch), 85_RF(Previous
For wheel rolls), 85_RR(For rear wheel roll)
In these low-pass filters, the operation units 63, 64, 65
The calculated control signal is set to a preset cutoff frequency X_G1, X
_G2, X_G3, X_G4Control signal is cut off when
And the cutoff frequency X_G1~ X _G4Outputs only the following signals
It is.

FIG. 9 shows the frequency characteristics (cutoff frequencies X _G1 , X _G2 = 1 Hz) of the bounce filter 85 _B and the pitch filter 85 _P. FIG. 10 shows the roll filters 85 _RF and 85 _RR . Frequency characteristics (cutoff frequency X
_G3 , X _G4 = 5 Hz). Torsion control system Next, in the control system D, reference numeral 80 inputs the hydraulic pressure signals P _FR , P _FL of the two cylinder pressure sensors 13 _FR , 13 _FL on the front wheel side, and inputs the total hydraulic pressure (P _FR) on the front wheel side. + P _FL ), a front wheel side hydraulic pressure ratio calculation unit 70a that calculates a ratio P _f P _f = (P _FR −P _FL ) / (P _FR + P _FL ) of a hydraulic pressure difference (P _FR −P _FL ) of the left and right wheels to the + P _FL ) a Wopu controller 70 consisting of the same liquid pressure ratio _{Pr P r = (P RR -P} RL) / (P RR + P RL) wheel side liquid pressure ratio calculating section 70b after calculating a rear wheel side. After the liquid pressure ratio P _r of the rear wheel side by a predetermined multiplication by a gain factor omega _F, which subtracts from the front side of the liquid pressure ratio P _f, and the results, as well as a predetermined multiple in gain coefficient omega _A, the front wheel in multiplies a predetermined gain factor omega _C, then inverted and in order to uniform between the left and right wheels a control amount for each wheel, in the control system D, the flow rate signal Q _FR4 of the corresponding flow control valves 9, Q _FL4, Q _RR4 and _QRL4 are obtained.

Low-pass filters 75 _FR , 75 _FL , 75 _RR , 75 _RL are provided between the cylinder pressure sensors 13 _FR- 13 _RL and the calculation units 70 a, 70 b, respectively, and these low-pass filters 75 _FR- 75 _RL are arranged. _RL is a hydraulic pressure signal P _FR , P _FL , P _RR , from the cylinder pressure sensors 13 _{FR to} 13 _RL .
Cutoff frequency P _RL is preset _{X P1, X P2, X P3} , X
When the vehicle height exceeds _P4 , the vehicle height displacement signals P _{FR to} P _RL are cut off, and the vehicle height displacement signals P _FR to below the cut-off frequencies X _{P1 to} X _P4 are cut off.
It outputs only the _PRL . Roll control correction system Next, in the control system E, 90 is the lateral acceleration sensor 1
Enter the lateral acceleration signal Y _G 6, based on the gain factor K _G, which is a control unit for calculating a control quantity for suppressing the lateral acceleration of the vehicle. The control amount calculated by the control unit 90, after the control ratio in the front and the rear side is changed by a factor A _GF, by reversing the sign in the right wheel and left wheel, the corresponding flow control valves Nine flow signals Q _FR5 , _QRL5 , Q
_RR5 and _QRL5 are obtained.

The lateral acceleration sensor 16 and the controller 90
A low-pass filter 91 is provided between the low-pass filters.
The filter 91 is a lateral acceleration signal from the lateral acceleration sensor 16
Y_GIs a preset cutoff frequency X_YIf you exceed
Lateral acceleration signal Y_GAnd cutoff frequency X_YBelow vehicle height
Displacement signal Y_GOutput only. As above
Then, the vehicle height change of the flow signal determined for each flow control valve 9 is performed.
Order component Q _FR1, Q_FL1, Q_RR1, Q_RL1, Vehicle height displacement velocity component
Q_FR2, Q_FL2, Q_RR2, Q_RL2, Vertical acceleration component Q_FR3,
Q_FL3, Q_RR3, Q_RL3, Pressure component Q_FR4, Q_FL4, Q_RR4,
Q_{R L4}, And the lateral acceleration component Q_FR5, Q_FL5, Q_RR5, Q_RL5
Are finally added and the correction unit 100_FR, 100_FL, 1
00_RR, 100_RLAnd the correction value K_H1,
K_H2, K_H3, K_H4To the final total flow signal
No. Q_FR, Q_FL, Q_RR, Q_RLIs obtained. <Active filter> Next, characteristics I to III of the present embodiment will be described.
The controller 19 of this suspension device
Cutoff frequency of the active filter used
Will be described.System A and System C filters FIG. 11 shows a vibration model for one wheel of the vehicle in FIG.
You. In FIG. 11, PC represents a fluid cylinder, and FIG.
Of the cylinder 3. Provided on the right side of the cylinder PC
C and K represent gas springs and correspond to gas spring 5 in FIG.
I do. The flow rate to the cylinder PC is specified by the signal QV.
You. When the cylinder PC is considered as a “spring”, M in FIG.₁
Is the "unsprung load" of the wheels, etc._TwoIs the "ba
Neighboring load ". Road surface position X₀And unsprung
X is the position of the load (wheel)₁And the sprung load (body) position
X_TwoIn the figure, X_Two-X₁Is the height sensor 15
To the output, the second derivative of X2, d / dt^Two(X_Two) Is the vertical G sensor
15 outputs. In the model of FIG. 11, the cylinder QC
Command flow QV to (X_Two-X₁) To gain (K₁+ K
_Twos) to give feedback (s is a differential operator), and d / dt^Two(X
_Two) To gain K_ThreeDetermined by feedback in
It is.

FIGS. 12 to 15 are based on the model of FIG.
Respectively, the sprung displacement (X
_Two) Characteristics, ride comfort (X_Two-X₁) Characteristics, grounding (X₁Special
Characteristics and command flow rate (QV) frequency characteristics. Gain K₁,
K_Two, K_ThreeThe vehicle height displacement and acceleration displacement
Feedback should be provided in the direction
The characteristics shown in these figures are around 1 Hz and around 10 Hz.
Indicates that a resonance is occurring at
Indicates that just changing the
You. Then, the sprung displacement (X_Two) Features
According to the gender diagram, K₁Is large (characteristic 301),
K ₁, K_ThreeIs set to 1 as compared with the case where is set to normal (characteristic 300).
Resonance around Hz is increased. Also, K_ThreeJust the big
Comb or K₁And K_Three1 Hz around
Side resonance is reduced. In addition, the grounding characteristics shown in FIG.
According to K₁When resonance is increased, resonance occurs around 1 Hz.
Then K_ThreeWhen resonance is increased, resonance occurs around 10 Hz.
You. Therefore, K₁And K_ThreeTo bounce and roll
The response control of the sprung displacement control by
Also, as shown in FIG.
Deterioration (deterioration of steering stability) has occurred on the contrary. Only
Then K₁The rider's heart is around 1Hz
Despite the deterioration of the ground, the riding comfort is improving around 10 Hz.
You. That is, K_ThreeIs grounding at around 10Hz (steering stability)
And the ride comfort is giving the opposite effect. So figure
Cutoff frequency of extremely low frequency of 1 to 4 Hz as shown in FIG.
The filter having the wave number is replaced with the filter 80 of FIG._B, 8
0_P, 80_RF, 80_RROr the filter 85 of FIG._B, 8
5_P, 85_RF, 85_RRIf used for around 4-10Hz
Deterioration of the grounding property and the riding comfort can be suppressed. Paraphrase
To keep the filter cutoff frequency low.
Reduces the responsiveness of the active suspension
The ride comfort can be emphasized. Place
The bounce, pitch and roll are all driver's comfort
It does not contribute equally to the earth. In particular, the roll is
Posture changes from side to side, and the grounding load also changes from side to side.
It has a great effect on maneuverability. Therefore, low
For low noise, lower the gain to lower the roll suppression effect.
Rather than bounce or pitch
To increase the response to roll displacement (transient roll
Prevention) can improve the maneuverability.
Therefore, in this embodiment, FIGS. 7 and 8 (or FIGS.
10) As shown in FIG.
_B(Or 85_B) Cutoff frequency (5Hz)
Bounce and pitch filters (80_P, 80_RF,
80_RR, 85_P, 85_RF, 85_RR) Cutoff frequency
(1 Hz). That is, about 1 Hz
For vehicle body displacement (vehicle height displacement and vertical G displacement)
The controls for the dance, pitch and roll are the same.
Bounce for 2Hz-5Hz displacement
Control and pitch control become ineffective, but roll control
Is still working. As a result, roll control is
Performs better responsiveness to dance control and pitch control
As a result, the transient roll can be prevented.

Thus, the cutoff frequency of the filter used for controlling the bounce component, controlling the pitch component, and controlling the roll component in the vehicle height control system A and the vehicle height displacement suppression system C is set to a low frequency of 1 to 5 Hz or less. As a result, it is possible to prevent the deterioration of the grounding property and the riding comfort, which occur near 10 Hz. Further, the cutoff frequency of each of these filters can be set independently of the cutoff frequency of the other filters, and the cutoff frequency of the roll component is set higher than the cutoff frequency of the bounce (or pitch). By doing so, the occurrence of a transient roll can be prevented. Filter 17 filters and System E System C, shows the frequency characteristic of the low-pass filter X _V 91 being used for roll control correction system E. As shown in the drawing, the cut-off frequency of the filter X _V is set to 7 Hz, 9, filter 85 _B and 85 _P or 85 which is used in the vertical G suppression system C shown in FIG. 10 _R
Is set higher than the cutoff frequency (1 Hz, 5 Hz).

That is, the contribution to the control by the upper and lower G signals is limited to a relatively low frequency range as compared to the contribution to the control by the horizontal G signal, thereby suppressing the oscillation of the control by the upper and lower G signals having a large amount of high frequency components. be able to. on the other hand,
Since the horizontal G signal originally has few high frequency components, the oscillation phenomenon is not promoted even if the cutoff frequency is extended to a high frequency as shown in FIG. Fluctuation of the vehicle body motion due to suppression of the contribution of the high frequency components of the upper and lower G signals can be prevented by increasing the gain in the high frequency range of the horizontal G signal relative to that of the upper and lower G signals. That is, it is possible to particularly prevent a transitional roll motion. <Modifications> The present invention can be variously modified without departing from the spirit thereof.

For example, in the above embodiment, the cutoff frequency (X _G3 ,
X _G4 ) is set to 5 Hz. However, if the present invention is particularly focused on preventing the occurrence of a transient roll motion, the cut-off frequency _XY of the filter 91 for the horizontal G signal is set to 5 Hz as shown in FIG. The cutoff frequencies (X _G3 , X _G4 ) of the upper and lower G signal filters 85 _RF and 85 _RR are set to 3 as shown in FIG.
Hz may be used. The aforementioned feature II is shown in FIG. 7 (or FIG. 9).
As shown in FIG. 8 and FIG. 8 (or FIG. 10), the cutoff frequency of the roll component is obtained by making the cutoff frequency relatively higher than that of the bass or pitch. 18 and FIG.
In the setting of the cut-off frequency as in the modification shown in FIG. 9, the condition that the cut-off frequency of the roll component is made relatively higher than that of the bass or pitch is maintained. The effect is obtained. And the top and bottom G
Since the condition that the cutoff frequency (3 Hz) for the signal is lower than that (5 Hz) for the horizontal G signal is also maintained, the oscillation phenomenon due to the high frequency components of the upper and lower G signals is suppressed, and the compensation by this suppression is performed by the horizontal G signal The effect that the roll motion can be prevented by increasing the gain in the high frequency range can also be obtained.

In the above embodiment, the filter 80
_B(85_B), 80_P(85_P), 80_R(85_R) 91 one
Although the secondary response filter was used,
Good. In the embodiment, the filter 80_B(8
5_B), 80_P(85_P), 80_R(85_R), Each, act
Arithmetic unit 80_B(85_B) And the adder 90 (97),
80_P(85_P) And the adder 91 (98), the operation unit 80
_RF, 80_RR(85_RF, 85 _RR) And adders 92 and 93 (9
9, 110), but these filters
Of the adders 50, 51, 52 (60, 61, 62)
It may be provided immediately before it.

[0046]

As described above, the suspension system for a vehicle according to the present invention can change the characteristics of the suspension by controlling the supply and discharge of fluid to and from the fluid cylinders disposed between the vehicle body and each wheel. In a suspension system for a vehicle, a sensor means for detecting a vertical acceleration signal of the vehicle body, a sensor means for detecting a lateral acceleration signal of the vehicle body, and each of the two signals detected are separately blocked. Low-pass filter means; and control means for controlling supply and discharge of a flow rate to and from the fluid cylinder using the two signals output from the low-pass filter means as parameters, wherein the vertical acceleration set in the low-pass filter means is provided. The cutoff frequency for the signal is the cutoff frequency for the lateral acceleration signal. Wherein the set lower than.

That is, suspension control oscillation can be prevented by making the contribution of the upper and lower G signals having a high frequency fluctuation component relatively lower than the contribution of the horizontal G signal having a low high frequency fluctuation. In addition, since the high-frequency gain of the horizontal G signal is increased by the cut of the high frequency of the upper and lower G signals, the roll phenomenon that occurs transiently can be effectively prevented.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of the present invention.

FIG. 2 is a block diagram of a suspension device according to an embodiment to which the present invention is applied.

FIG. 3 is a diagram showing a hydraulic system according to the embodiment of FIG. 2;

FIG. 4 is a block diagram illustrating a schematic configuration of functions of a control system according to the embodiment.

FIG. 5 is a diagram showing a detailed configuration of a control system according to the embodiment.

FIG. 6 is a diagram showing a detailed configuration of a control system according to the embodiment.

FIG. 7: Filters 80 _B and 80 _P used for vehicle height control
FIG. 4 is a graph showing characteristics of the present invention.

FIG. 8 shows filters 80 _RF and 80 used for vehicle height control.
FIG. 3 is a graph showing characteristics of _RR . .

FIG. 9 shows filters 85 _B and 8 used for vertical G control.
Graph showing the 5 _P characteristics.

FIG. 10 shows a filter 85 _RF used for vertical G control,
The graph which shows the characteristic of 85 _RR .

FIG. 11 is a diagram modeling suspension control of the embodiment.

FIG. 12 is a characteristic diagram showing results of sprung displacement characteristics obtained by the model of FIG. 11;

FIG. 13 is a characteristic diagram showing a result of ride comfort characteristics obtained by the model of FIG. 11;

FIG. 14 is a characteristic diagram showing a result of a grounding characteristic obtained by the model of FIG. 11;

FIG. 15 is a characteristic diagram showing a result of a command flow characteristic obtained by the model of FIG. 11;

FIG. 16 is a diagram showing general characteristics of a filter used in the vehicle height control system and the vertical G control system.

FIG. 17 is a characteristic diagram of a low-pass filter 91 used in the roll control correction system E.

FIG. 18 is a diagram showing characteristics according to a modified example of the filter 91 used in the roll control correction system E.

FIG. 19 is a diagram showing characteristics according to a modification of the filter 85 used in the upper and lower G control system.

[Explanation of symbols]

3 ... fluid cylinder, 5 ... gas spring, 9 ... control valve, 5
0, 51, 52, 60, 61, 62...
85, 91 ... low-pass filter

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-63-279915 (JP, A) JP-A-3-182826 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B60G 17/015

Claims (1)

(57) [Claims] 1. A suspension apparatus for a vehicle capable of changing the characteristics of a suspension by controlling the supply and discharge of fluid to and from a fluid cylinder disposed between a vehicle body and each wheel, wherein a vertical acceleration signal of the vehicle body is detected. Sensor means for detecting a lateral acceleration signal of the vehicle body; low-pass filter means for separately blocking high-frequency components of each of the two detected signals; and the above-mentioned signal outputted from the low-pass filter means. Control means for controlling supply and discharge of a flow rate to and from the fluid cylinder using the two signals as parameters, wherein a cutoff frequency for the vertical acceleration signal set in the low-pass filter means is cut for a lateral acceleration signal. Set lower than OFF frequency
A suspension device for a vehicle, comprising: