JPH09220919A - Active suspension - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sufficient damping effect even without generating a large control force by an active suspension devised to favourably maintain a car body position by reducing an input of oscillation from a spring lower side to a spring upper side. SOLUTION: A control coefficient setting part 58 to set each control coefficient to be used by a control force computing part 54 in accordance with a car speed detection value V to be supplied is provided on a controller 30. The control coefficient setting part 58 is devised to discriminate a status easy to generate pitch resonance on a spring and a status easy to generate bounce resonance on the spring from each other, in case of judging that it is the status easy to generate the pitch resonance, set each of the control coefficients so that a phase of target control force on the side of a front wheel delays and a phase of target control force on the side of a rear wheel advances and in case of judging that it is the status easy to generate the bounce resonance on the spring, set each of the control coefficients so that the phase of the target control force on the side of the front wheel advances and the phase of the target control force on the side of the rear wheel delays.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the working fluid pressure of a fluid pressure cylinder separately inserted between a vehicle body and wheels.
Controlling according to the vertical vibration of the unsprung member at each wheel position reduces the vibration input from the unsprung side to the unsprung side to maintain a good vehicle attitude. It is designed so that a sufficient damping effect can be obtained without generating force.

[0002]

2. Description of the Related Art Conventional active suspensions include:
For example, JP-A-63-25820 previously proposed by the present applicant
There is one disclosed in Japanese Patent Publication No. 7 (1995). In this conventional active suspension, the vertical acceleration above the spring and the vertical acceleration below the spring are detected, and a command value corresponding to the vertical speed of vertical vibration is calculated based on the acceleration detection values of both of them.
The command value is supplied to each pressure control valve to generate a control force in the fluid pressure cylinder. That is, in this active suspension, not only the vertical vibration on the spring but also the vertical vibration on the unsprung part is detected. By generating and outputting the command value according to the unsprung vibration, the spring It was also possible to satisfactorily control the lower vibration.

[0003]

Certainly, according to the conventional active suspension as described above, a control force is generated according to the sprung mass vibration and the unsprung mass vibration, but the damping effect can be obtained. , In order to obtain a sufficient damping effect, it is necessary to generate control force that can cancel the unsprung vibration at each wheel position by the individual fluid pressure cylinders arranged at each wheel position. It is necessary to generate a large control force corresponding to that. For this reason, since it is necessary to use a fluid pressure cylinder or a hydraulic pressure source capable of generating a large control force so as to cope with an expected vibration input,
There is an unsolved problem that the size of the device is increased and energy consumption is increased, which leads to deterioration of fuel efficiency.

The present invention has been made by paying attention to the unsolved problems in the prior art as described above, and provides an active suspension capable of obtaining a sufficient vibration damping effect without generating a large control force. It is intended to be provided.

[0005]

In order to achieve the above object, the invention according to claim 1 provides a fluid pressure cylinder separately inserted between a vehicle body and each wheel, and an operation of each of these fluid pressure cylinders. A pressure control valve for controlling fluid pressure only in accordance with a command value, an unsprung vibration detecting means for detecting vertical vibration of an unsprung member at each wheel position of a vehicle body, and an unsprung vibration detected by this unsprung vibration detecting means. In an active suspension having a control means for generating the command value according to a detected value and supplying the command value to the pressure control valve, a vehicle speed detecting means for detecting a vehicle speed, and a vehicle speed detected value detected by the vehicle speed detecting means. Accordingly, phase characteristic control means for controlling the phase characteristic of the command value with respect to the unsprung vibration detection value independently of the front and rear wheels is provided.

According to a second aspect of the invention, in the active suspension according to the first aspect of the invention, the phase characteristic control means includes a transmission force to the sprung member on the front wheel side and a spring on the rear wheel side. The phase characteristics are controlled independently of the front and rear wheels so that the phase difference with the transmission force to the upper member departs from the phase difference that easily causes sprung resonance. And Claim 3
According to a second aspect of the present invention, in the active suspension according to the second aspect of the present invention, the phase characteristic control unit determines whether or not pitch resonance is likely to occur on a spring based on the vehicle speed detection value. When the pitch resonance determining means determines that the pitch resonance is likely to occur, the process for advancing the phase characteristic on the front wheel side and the process for delaying the phase characteristic on the rear wheel side are performed. At least one of the processes is executed.

Further, the invention according to claim 4 is the active suspension according to claim 3,
The pitch resonance determining means determines that pitch resonance is likely to occur on the spring when the value obtained by dividing the vehicle speed detection value by twice the wheel base is equal to or substantially equal to the sprung pitch resonance frequency. According to a fifth aspect of the invention, in the active suspension according to the third or fourth aspect of the invention, the unsprung vibration detection means detects a unsprung vertical velocity as vertical vibration of the unsprung member. Processing for advancing the phase characteristic of the front wheel side in the phase characteristic control means, which has lower vertical speed detection means and unsprung vertical displacement detection means for detecting unsprung vertical displacement as vertical vibration of the unsprung member. Is a process for generating the command value on the front wheel side by using an antiphase component of the unsprung vertical velocity as a main component, and a process for delaying the phase characteristic on the rear wheel side in the phase characteristic control means is for the unsprung vertical displacement. The processing is to generate the command value on the rear wheel side with the antiphase component as the main component.

On the other hand, according to a sixth aspect of the invention, in the active suspension according to the second to fifth aspects of the invention, the phase characteristic control means is apt to cause bounce resonance on the spring based on the vehicle speed detection value. A process of delaying the phase characteristic on the front wheel side and a rear wheel having a bounce resonance determination means for determining whether or not the situation is present, and when the bounce resonance determination means determines that the bounce resonance is likely to occur At least one of the processes for advancing the phase characteristic on the side is executed.

The invention according to claim 7 is the active suspension according to claim 6, wherein:
The bounce resonance determination means determines that bounce resonance is likely to occur on the spring when the value obtained by dividing the vehicle speed detection value by the wheel base is sufficiently larger than the sprung bounce resonance frequency. Further, the invention according to claim 8 is the active suspension according to claim 6 or 7, wherein the unsprung vibration detection means detects a unsprung vertical velocity as vertical vibration of the unsprung member. A process for delaying the phase characteristic of the front wheel side in the phase characteristic control means, which has lower vertical speed detection means and unsprung vertical displacement detection means for detecting unsprung vertical displacement as vertical vibration of the unsprung member. Is a process for generating the command value on the front wheel side by using a reverse phase component of the unsprung vertical displacement as a main component, and a process for advancing the phase characteristic on the rear wheel side in the phase characteristic control means is for the unsprung vertical velocity. The processing is to generate the command value on the rear wheel side with the antiphase component as the main component.

According to a ninth aspect of the invention, in the active suspension according to the first to eighth aspects of the invention, the control means sets the command value according to a predetermined function based on the unsprung vibration detection value. The phase characteristic control means controls the phase characteristic independently for the front and rear wheels by setting the function independently for the front and rear wheels according to the vehicle speed detection value.

According to a tenth aspect of the present invention, in the active suspension according to the first to eighth aspects of the invention, the control means refers to a predetermined table based on the unsprung vibration detection value and refers to the predetermined table. A command value is calculated, and the phase characteristic control means controls the phase characteristic independently for the front and rear wheels by selecting the table independently for the front and rear wheels according to the vehicle speed detection value.

Further, the invention according to claim 11 is the active suspension according to any one of claims 1 to 8, wherein the control means filters the unsprung vibration detection value to calculate the command value. The phase characteristic control means controls the phase characteristic independently for the front and rear wheels by setting the filter coefficient in the filtering process independently for the front and rear wheels.

According to a twelfth aspect of the present invention, in the active suspension according to the first to eleventh aspects of the invention, the unsprung vibration detection means delays the unsprung vibration detection value on the front wheel side. A rear wheel unsprung vibration estimating means for estimating unsprung vibration on the rear wheel side is provided, and the estimated value of the unsprung vibration on the rear wheel side is set as the unsprung vibration detected value on the rear wheel side.

According to a thirteenth aspect of the present invention, in the active suspension according to the first to eleventh aspects of the present invention, the unsprung vibration detection means detects a road surface unevenness for detecting an unevenness of a traveling road surface in front of the vehicle. Means and an unsprung vibration estimating means for estimating the unsprung vibration of the wheel position based on the road surface unevenness detection value detected by the road surface unevenness detection means, and the estimated value of the unsprung vibration is the unsprung vibration. The detection value is used.

Here, in the invention according to claim 1,
When the unsprung vibration detection means detects the vertical vibration of the unsprung member at each wheel position, the control means generates a command value according to the unsprung vibration detection value and outputs it to the pressure control valve.
A control force corresponding to the vertical vibration of each unsprung member is generated in each of the fluid pressure cylinders individually interposed between the vehicle body and each wheel. On the other hand, when the vehicle speed is detected by the vehicle speed detection means, the phase characteristic control means controls the phase characteristic of the command value with respect to the unsprung vibration detection value independently of the front and rear wheels in accordance with the vehicle speed detection value. As a mode of controlling the phase characteristics independently of the front and rear wheels, not only a mode of changing both the phase characteristics of the front wheels and the phase characteristics of the rear wheels, but the phase characteristics of the front wheels are fixed and the phase of the rear wheels is fixed. It also includes a mode in which only the characteristics are changed, and a mode in which the phase characteristics on the rear wheel side are fixed and the phase characteristics on the front wheel side are changed, on the contrary, are also included.

If the phase characteristic control means controls the phase characteristic of the command value with respect to the unsprung vibration detection value independently of the front and rear wheels, the control force generated by the fluid pressure cylinder cannot cancel the transmission and is input to the spring. It is possible to arbitrarily change the phase difference between the front wheel side and the rear wheel side of the force. On the other hand, if the phase characteristics of the command value with respect to the unsprung vibration detection value are equal on the front wheel side and the rear wheel side, the force transmitted to the sprung member on the front wheel side and the force transmitted to the sprung member on the rear wheel side are transmitted. The phase difference with the force is a constant value determined by the wheel base and the road surface irregularity period. For example, if the half cycle of road surface irregularity matches or substantially matches the wheel base, the front wheel side transmission force and the rear wheel side transmission force are in opposite phases, and the road surface irregularity cycle is sufficiently longer than the wheel base. Then, the front wheel side transmission force and the rear wheel side transmission force are in phase. Then, if the input is in the opposite phase, a pitch is likely to occur in the vehicle body, and if the input is in-phase, the bounce is likely to occur in the vehicle body. Therefore, the transmission force on the front wheel side and the rear wheel side is input in the opposite phase. When the vehicle speed reaches a specific vehicle speed range, sprung mass pitch resonance occurs, and when the vehicle speed reaches another specific vehicle speed range when the front wheel side and rear wheel side transmission forces are input in the same phase, sprung mass bounce resonance occurs. Come to do. Therefore, in order to prevent such resonance when the phase characteristic is fixed, it is necessary to completely cancel the vibration input from the unsprung member to the sprung member by the control force generated by the fluid pressure cylinder. It requires a lot of control.

However, according to the first aspect of the present invention, since the phase characteristic of the command value for the unsprung vibration can be controlled independently of the front and rear wheels according to the vehicle speed, the front wheel which causes sprung resonance as described above. It is possible to arbitrarily adjust the phase difference between the transmission forces on the rear side and the rear wheel side to avoid the phase difference between the transmission forces that easily cause sprung resonance. And
According to the invention of claim 2, when the phase characteristic control means controls the phase characteristic of the command value with respect to the unsprung vibration independently of the front and rear wheels according to the vehicle speed, the phase difference between the transmission forces on the front wheel side and the rear wheel side is the spring. The phase difference is separated from the phase difference where the upper resonance is likely to occur, and the sprung resonance is less likely to occur.

For example, in the invention according to claim 3, when the pitch resonance determining means determines that pitch resonance is likely to occur on the spring based on the vehicle speed, the phase characteristic control means causes the phase on the front wheel side. At least one of the process of advancing the characteristic and the process of delaying the phase characteristic on the rear wheel side is executed.
When the former process is executed, the transmission force on the front wheel side is delayed, and when the latter process is executed, the transmission force on the rear wheel side is advanced, and both processes are executed. Since both the delay and the advance occur, the transmission force that was in the opposite phase comes closer to the in-phase. For this reason, even if the road surface irregularity has a shape in which pitch resonance is likely to occur, pitch resonance is less likely to occur in the vehicle body.

Further, in the invention according to claim 4, the pitch resonance determining means determines that the value (V / 2L) obtained by dividing the vehicle speed detection value V by twice the wheel base L is the sprung pitch resonance frequency (usually 1). It is determined that pitch resonance is likely to occur on the spring when it is equal to or approximately equal to (about 2 Hz). Since the wheel base L has a constant value for each vehicle and the variable is only the vehicle speed detection value V, it can be determined based on only the vehicle speed detection value V whether pitch resonance is likely to occur. .

Further, in the invention according to claim 5, the unsprung vertical velocity is detected by the unsprung vertical velocity detecting means,
When the unsprung up / down displacement detecting means detects the unsprung up / down displacement, the phase characteristic control means generates a command value for the front wheel with the antiphase component of the unsprung up / down velocity as a main component, and the unsprung up / down displacement. At least one of the processes for generating the command value on the rear wheel side is executed by using the anti-phase component as the main component. However, since the speed is advanced by 90 degrees with respect to the displacement, when the former process is executed, the front wheel side is executed. The command value of 1 advances and the command value of the rear wheel side delays when the latter process is executed. Therefore, the action of the invention according to claim 3 is surely exhibited.

On the other hand, in the invention according to claim 6, when the bounce resonance determining means determines that the bounce resonance is likely to occur on the spring based on the vehicle speed, the phase characteristic control means causes the front wheel side At least one of the process of delaying the phase characteristic and the process of advancing the phase characteristic on the rear wheel side is executed. When the former process is executed, the front wheel-side transmission force is advanced, and when the latter process is executed, the rear-wheel-side transmission force is delayed, and both processes are executed. Since both the lead and the lag occur, the phase difference of the transmission force close to the in-phase becomes large. Therefore, even if the road surface irregularity has a shape that easily causes the bounce resonance, the bounce resonance does not easily occur in the vehicle body.

Further, in the invention according to claim 7, in the bounce resonance determining means, the value (V / L) obtained by dividing the vehicle speed detection value V by the wheel base L is a sprung bounce resonance frequency (usually about 1 to 2 Hz). ) Is sufficiently large (for example, 10 to
(15 times or more), it is determined that bounce resonance is likely to occur on the spring. Since the wheel base L has a constant value for each vehicle and the variable is only the vehicle speed detection value V, it can be determined based on only the vehicle speed detection value V whether or not bounce resonance is likely to occur. .

In the invention according to claim 8, the unsprung vertical velocity is detected by the unsprung vertical velocity detecting means,
When the unsprung up / down displacement is detected by the unsprung up / down displacement detecting means, the phase characteristic control means generates a command value on the front wheel side by using an antiphase component of the unsprung up / down displacement as a main component, and the unsprung up / down velocity. At least one of the processes for generating the command value on the rear wheel side is executed by using the anti-phase component as the main component. However, since the displacement is delayed by 90 degrees in phase with respect to the speed, when the former process is executed, the front wheel side is executed. Is delayed, and the command value on the rear wheel side is advanced when the latter process is executed. Therefore, the action of the invention according to claim 6 can be surely exhibited.

Further, as a calculation mode of the command value in the control means, the command value is calculated by incorporating the unsprung vibration detection value into a predetermined function (claim 9), and the table is calculated based on the unsprung vibration detection value. Various modes are conceivable such as referring to calculate the command value (claim 10), filtering the unsprung vibration detection value to calculate the command value (claim 11), and the like. Then, the phase characteristic of the command value with respect to the unsprung vibration detection value can be changed by changing the function in a calculation mode using a function, and the contents of the table can be changed in a calculation mode using a table. Therefore, it can be changed, and in the case of using a filter, it can be changed by changing the filter coefficient. Therefore, in the invention according to claim 9, the phase characteristic control means sets the function independently for the front and rear wheels according to the vehicle speed detection value, and in the invention according to claim 10, the phase characteristic control means detects the vehicle speed. In the invention according to claim 11, the front and rear wheels are independently selected according to the value, and the phase characteristic control means sets the filter coefficient independently for the front and rear wheels according to the vehicle speed detection value. Even if there is, the phase characteristic of the command value with respect to the unsprung vibration detection value is controlled independently of the front and rear wheels.

Further, in the invention according to claim 12,
When the rear wheel side unsprung vibration estimation means delays the front wheel side unsprung vibration detection value to obtain the estimated value of the rear wheel unsprung vibration, the estimated value of the rear wheel unsprung vibration is It is used as a detection value for the unsprung vibration on the wheel side. In other words, the vibrations generated under the spring are mainly caused by road surface irregularities, and it can be considered that the loci of the front wheels and the loci of the rear wheels are almost the same. The unsprung vibration can be regarded as substantially the same vibration except that there is a phase difference determined by the vehicle speed and the wheel base. Therefore, if the unsprung vibration detection value for the front wheel is delayed by the unsprung vibration estimation means for the rear wheel, the unsprung vibration for the rear wheel can be obtained.

Further, in the invention according to claim 13, when the road surface unevenness detecting means detects the unevenness of the traveling road surface in front of the vehicle, the unsprung vibration estimating means detects the wheel position based on the road surface unevenness detection value. The unsprung vibration is estimated, and the estimated value of the unsprung vibration is used as the unsprung vibration detection value. That is, as described above, the vibrations generated under the spring are mainly caused by the road surface irregularity,
If the unevenness of the road surface on which the wheel passes is detected, the unevenness information of the traveling road surface on which the wheel is passing can be obtained by, for example, appropriately delaying the detected value of the road surface unevenness. The vibration can be obtained.

[0027]

According to the first aspect of the present invention, the phase characteristic control means controls the phase characteristic of the command value with respect to the unsprung vibration detection value independently of the front and rear wheels according to the vehicle speed detection value. The phase difference between the front wheel side and the rear wheel side of the transmission force that is input to the spring without being canceled out by the control force generated by the cylinder can be changed arbitrarily according to the vehicle speed, so the entire spring There is an effect that the vibration of can be controlled to a desired state.

Particularly, according to the second aspect of the invention, the phase characteristic control means controls the phase characteristic so that the phase difference between the transmission forces on the front wheel side and the rear wheel side deviates from the phase difference at which sprung resonance is likely to occur. Therefore, sprung resonance is less likely to occur, and there is an effect that a good sprung posture can be maintained even if a large control force is not generated in the fluid pressure cylinder. According to the third aspect of the present invention, even if the road surface irregularity has a shape that easily causes pitch resonance, pitch resonance does not easily occur in the vehicle body. Therefore, even if a large control force is not generated by fluid pressure, the pitch resonance does not occur. This has the effect of avoiding resonance and maintaining a good sprung posture.

According to the fourth aspect of the invention, it is possible to determine whether the pitch resonance is likely to occur based on only the vehicle speed detection value V, so that the processing in the phase characteristic control means can be surely performed in real time. effective. Also,
According to the invention of claim 5, at least one of the processing for advancing the command value on the front wheel side and the processing for delaying the command value on the rear wheel side can be surely executed, so that the effect of the invention according to claim 3 can be reliably obtained. You can

On the other hand, according to the sixth aspect of the invention, even if the road surface irregularity has a shape that easily causes bounce resonance, bounce resonance is less likely to occur in the vehicle body, so a large control force is not generated by fluid pressure. However, there is an effect that bounce resonance can be avoided and a good sprung posture can be maintained. Further, according to the invention of claim 7, it is possible to determine whether or not the bounce resonance is likely to occur based on only the vehicle speed detection value V, so that the processing in the phase characteristic control means can be reliably performed in real time. is there.

Further, according to the invention of claim 8, at least one of the processing of delaying the command value on the front wheel side and the processing of advancing the command value on the rear wheel side can be surely executed. Therefore, the effect of the invention according to claim 6 Can be surely obtained. further,
According to the inventions of claims 9 to 11, the phase characteristics of the command value with respect to the unsprung vibration detection value can be reliably controlled independently of the front and rear wheels, corresponding to the calculation mode of the command value in the control means.
Moreover, according to the invention of claim 10, since the command value is obtained by using the table, there is an effect that it is possible to make a fine setting which is difficult with a function. For example, since the command value is calculated using the filter, there is an effect that the control can be easily optimized.

According to the twelfth aspect of the invention, the means for directly detecting the unsprung vibration on the rear wheel side is unnecessary, which is advantageous in terms of cost. Since the unsprung vibration on the wheel side can be obtained in advance, it is possible to compensate for the control delay due to the calculation time in the control means, the response characteristics of the fluid pressure cylinder, etc., and to reduce the sprung vibration on the rear wheel side. It can be performed with higher accuracy.

According to the invention of claim 13,
Since the unsprung vibration at each wheel position can be obtained in advance, it is possible to compensate for the control delay due to the calculation time in the control means, the response characteristics of the fluid pressure cylinder, etc., and to reduce the sprung vibration at each wheel position. Can be performed with higher accuracy.

[0034]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 9 are views showing a first embodiment of the present invention. First, the structure will be described.
In FIG. 1, 10FL to 10RR are front left to rear right wheels, 12
Is a wheel side member as an unsprung member, 14 is a vehicle body member as an sprung member, and 16 is an active suspension.

The active suspension 16 has hydraulic cylinders 18FL to 18RR as fluid pressure cylinders provided separately between the vehicle body side member 14 and each wheel side member 12, and operating hydraulic pressures of the hydraulic cylinders 18FL to 18RR. The pressure control valves 20FL to 20RR to be adjusted respectively and the hydraulic power source 22 of this hydraulic system
And an accumulator 24, 24 for accumulating pressure, which is inserted between the hydraulic pressure source 22 and the pressure control valves 20FL to 20RR, and a controller 30 that individually controls the output pressure of the pressure control valves 20FL to 20RR. . Further, the active suspension 16 includes coil springs 36, ..., 36, which are individually installed in parallel between the wheel side member 12 and the vehicle body member 14 with respect to the hydraulic cylinders 18FL to 18RR, and the hydraulic cylinder 1
A throttle valve 32 and a vibration absorbing accumulator 34, which individually communicate with pressure chambers L of 8FL to 18RR described later, are included.
Here, each coil spring 36 has a relatively low spring constant and supports a static load of the vehicle body.

Each of the hydraulic cylinders 18FL to 18RR has a cylinder tube 18a.
A lower pressure chamber L closed by the piston 18c is formed in a. And the cylinder tube 18a
Is attached to the wheel side member 12, and the upper end of the piston rod 18b is attached to the vehicle body side member 14.

Further, this active suspension 16
Has vertical acceleration sensors 28FL to 28RR for detecting unsprung vibrations corresponding to the positions of the wheels 10FL to 10RR, and a vehicle speed sensor 29 for detecting a vehicle speed. Each of the pressure control valves 20FL to 20RR has a valve housing having a spool slidably accommodated in a cylindrical insertion hole, and a proportional solenoid integrally provided in the valve housing. Is formed in. The supply port and the return port for the hydraulic oil of the pressure control valves 20FL to 20RR are connected to the hydraulic oil supply side and the hydraulic oil return side of the hydraulic source 22 via the hydraulic pipes 38 and 39 and the multi-valve unit 22A, and output. Port is hydraulic piping 40
The pressure chambers L of the hydraulic cylinders 18FL to 18RR are communicated with each other via. The multi-valve unit 22A
Is a relief valve for setting the line pressure, the hydraulic pipes 38 on the pressure control valves 20FL to 20RR side when the engine is stopped,
It is configured to include a check valve and the like for holding the pressure oil in 39.

Then, by controlling the value of the command current I (IFL to IRR) as the command value supplied to the exciting coil of the proportional solenoid of each pressure control valve 20FL to 20RR, the thrust and the output port by this command current I are controlled. So that the control pressure P corresponding to the command current I can be supplied from the output port to the pressure chamber L of the hydraulic cylinder 18FL (to 18RR). Has become.

That is, as shown in FIG. 2, the command current I and the control pressure P have a direct proportional relationship.
Is zero, the control pressure P is a predetermined offset pressure P _0.
From this state, when the command current I increases in the positive direction, the control pressure P increases with a predetermined proportional gain, and when it reaches the line pressure, it is saturated. Conversely, when the command current I increases in the negative direction, it is proportional to this. Are decreasing.

On the other hand, each vertical acceleration sensor 28FL to 28RR
Detects the vertical acceleration at each unsprung position, and as shown in FIG. 3, the vertical acceleration detection values X _g FL to X _g RR, which are voltage signals corresponding to the detected vertical acceleration, are transferred to the controller 3
0 is supplied. Here, the value of the vertical acceleration generated in the upward direction (the direction in which the wheel-side member 12 is lifted) is positive, and the value of the vertical acceleration generated in the downward direction is negative.

Further, the vehicle speed sensor 29 has wheels 10FL-1FL.
The vehicle speed is detected on the basis of the rotational speed of 0RR or the rotational speed of a drive system such as a transmission and a final reduction gear, and the vehicle speed detection value V that increases in proportion to the vehicle speed is used by the controller 3
0 is supplied. The controller 30 to which each detected value is supplied is actually configured to include a microcomputer, an A / D converter, an interface circuit such as a D / A converter, a driver circuit, etc., and its functional configuration is , As shown in FIG.

[0042] That is, the controller 30, an integrator 50 which integrates the vertical acceleration detection value X _g FL~X _g RR supplied for calculating a vertical velocity X _r FL~X _r RR at each unsprung position
When each vertical velocity X _r FL~X _r of the integrator 50 is calculated
Vertical integration X _{d at} each unsprung position by further integrating RR
Integrator 52 for calculating FL to X _d RR, and these integrators 50
And 52 each vertical velocity computed is X _r FL~X _r RR and the vertical displacement X _d FL~X _d RR in basis of the following (1) target control force generated by the hydraulic cylinders 18FL~18RR in accordance with equation FFL
.About.FRR, and a driver circuit 56 for converting and outputting the target control forces FFL to FRR calculated by the control force calculating unit 54 into command currents IFL to IRR for the pressure control valves 20FL to 20RR. And are equipped with.

Fi = − (Ci · X _r i + Ki · X _d i) (1) where i = FL to RR, C _i is the control coefficient corresponding to the damping force, and K _i is the spring force. Is the control coefficient to In addition,
For the integration operation in each of the integrators 50 and 52, for example, a primary filter as represented by the following (2) can be used, or various known numerical integration algorithms can be used.

T / (1 + Ts) (2) where T is the filter time constant, and in this case 0.1
Set to a larger value. s is a Laplace operator. Further, the controller 30 sets the control coefficients CFL to CRR and KFL to KRR based on the supplied vehicle speed detection value V and supplies the control coefficient calculation unit 54 with the control coefficient setting unit 58.
have. However, the setting of the control coefficients CFL to CRR and KFL to KRR in the control coefficient setting unit 58 and the supply to the control force calculation unit 54 are performed prior to the calculation of the target control forces FFL to FRR in the control force calculation unit 54. It is like this.

Here, in principle, the control coefficient setting unit 58 obtains a value (V / 2L) obtained by dividing the vehicle speed detection value V by twice the wheel base L, and this value (V / 2L) is this value. Pitch resonance determination processing that determines that pitch resonance is likely to occur on the spring when it matches or substantially matches the sprung pitch resonance frequency of the vehicle, and the vehicle speed detection value V is set to the wheel base L.
The value (V / L) divided by is obtained, and when the value (V / L) is sufficiently large (for example, 10 to 15 times or more) with respect to the sprung bounce resonance frequency of this vehicle, the bounce on the spring is performed. Bounce resonance determination processing for determining that resonance is likely to occur is executed, but in reality, the only variable in each processing is the vehicle speed detection value V, so the vehicle speed detection value V Based on only the size, the situation where pitch resonance is likely to occur on the spring and the situation where bounce resonance is likely to occur on the spring are discriminated.

For example, if the sprung pitch resonance frequency and the sprung bounce resonance frequency are both 1.4 Hz and the wheelbase is 2.7 m as an average vehicle value, the vehicle speed range where pitch resonance is likely to occur is obtained. The (first vehicle speed range) is about 27 km / h, and the vehicle speed range where bounce resonance is likely to occur (second vehicle speed range) exceeds 100 km / h.

That is, the first vehicle speed range and the second vehicle speed range
If the vehicle speed range is determined in advance based on the vehicle specifications, the vehicle speed detection value V is generated on the spring only by determining which vehicle speed range the vehicle speed detection value V is in or which vehicle speed range is close to. It is possible to determine the type of resonance that is easy. When the control coefficient setting unit 58 determines that pitch resonance is likely to occur on the spring based on the vehicle speed detection value V, the target control forces FFL to FFL obtained by the above equation (1) are calculated.
Of the RRs, the control coefficients CFL to CFR and KFL to KRR are set so that the phases of the target control forces FFL and FFR on the front wheel side are delayed and the phases of the target control forces FRL and FRR on the rear wheel side are advanced. It has become.

On the other hand, when the control coefficient setting unit 58 determines that the bounce resonance is likely to occur on the spring based on the vehicle speed detection value V, the target control obtained by the above equation (1). Of the forces FFL to FRR, the control coefficients CFL to CFL are set such that the phases of the target control forces FFL and FFR on the front wheel side are advanced and the phases of the target control forces FRL and FRR on the rear wheel side are delayed.
RR and KFL to KRR are set.

More specifically, the vertical speeds X _r FL to X _r RR
Since a physical quantity is progressing 90 degrees out of phase with the vertical displacement X _d FL~X _d RR, in the above (1), the control factor relating the control coefficient CFL~CRR related to the speed of the displacement KFL~ If it is made larger than KRR, the target control force FFL ~
Since the reverse phase component of the vertical velocity X _r FL~X _r RR is dominant in FRR, the target control force FFL~FRR becomes proceeds tendency. Conversely, when the large compared to the control coefficient CFL~CRR related control coefficient KFL~KRR displacement, in target control force FFL~FRR opposite phase component is dominant in the vertical displacement X _d FL~X _d RR Therefore, the target control forces FFL to FRR tend to progress.

[0050] It should be noted that the phase is advanced, the concept phase is delayed, vertical velocity X _r FL~X _r RR and vertical displacement X _d FL~X
_d RR is based on the case where the control force of the opposite phase is generated just for the unsprung vibration that is currently occurring, which is represented by both physical quantities of _d RR. Therefore, if the antiphase component of the displacement becomes dominant, the control force will be delayed.

Phase of control force and control coefficients CFL to CRR, K
Since the relationship with FL to KRR is as described above,
The control coefficient setting unit 58 in this embodiment is similar to that shown in FIG.
Each control coefficient CFL ~ with the tendency shown in (a) and (b)
CRR and KFL to KRR are set.

The relations shown in FIGS. 5 (a) and 5 (b) can be expressed by the following equations in different cases. 0 <V <25 km / h: CFL, CFR = C ₀ (V / 50 + 0.5) CRL, CRR = C ₀ (-V / 50 + 0.5) KFL, KFR = K ₀ (-V / 50 + 0.5) KRL , KRR = K ₀ (V / 50 + 0.5) 25 <V <50 km / h: CFL, CFR = C ₀ CRL, CRR = 0 KFL, KFR = 0 KRL, KRR = K ₀ 50 <V <100 km / h: _{CFL, CFR = C 0 (-V} / 50 + 2) CRL, CRR = C 0 (V / 50-1) KFL, KFR = K 0 (V / 50-1) KRL, KRR = K 0 (V / 50 + 2) V > 100 km / h: CFL, CFR = 0 CRL, CRR = C ₀ KFL, KFR = K ₀ KRL, KRR = 0 In addition, C ₀ and K ₀ in each of these equations are the wheels 10FL of the active suspension 16 respectively. Actual damping constant [N / m / s] and spring constant [N /
m].

Here, the processing executed in the controller 30 is summarized as shown in the flowchart of FIG. That is, first, in step 101 the vertical acceleration detection value X _g FL~X _g RR and the vehicle speed detecting value V is read, and then proceeds to step 102, the vertical acceleration detection value X _g FL~
The X _g RRs are respectively integrated in the integrator 50 to calculate the vertical velocities X _r FL to X _r RR. Step 10
3 proceeds to vertical displacement X _d FL~X _d RR is calculated vertical velocity X _r FL~X _r RR is integrated respectively in the integrator 52.

When each of these values is calculated, step 10
4, the control coefficient setting unit 5 is operated based on the vehicle speed detection value V in accordance with the function shown in FIGS. 5 (a) and 5 (b).
At 8, the control coefficients CFL to CRR and KFL to KRR are set. Then, the process proceeds to step 105 and step 1
Vertical velocity X _r FL~X _r RR calculated at 02,103, and the vertical displacement X _d FL~X _d RR, based on the respective control coefficients CFL~CRR and KFL~KRR set in step 104, the control force The calculation unit 54 calculates the target control forces FFL to FRR according to the above equation (1). When these target control forces FFL to FRR have been calculated, the routine proceeds to step 106, where the target control force FFL is calculated.
Command currents IFL to IRR corresponding to FL to FRR are output from the driver circuit 56 to the pressure control valves 20FL to 20RR. When the process of step 106 is completed, the process returns to step 101 and the above-described process is repeatedly executed.

Next, the overall operation of this embodiment will be described. Now, when the vehicle is assumed that the straight traveling a flat good road, vertical vibration is because not input to each wheel-side member 12, the vertical acceleration detection value X _g FL~X the vertical acceleration sensor 28FL~28RR outputs _g RR becomes zero. Therefore, the outputs of the integrators 50 and 52 in the controller 30 are also zero, so that the target control forces FFL to FRR calculated by the control force calculation unit 54 are related to the values of the control coefficients CFL to CRR and KFL to KRR. Not zero. Then, from the characteristics shown in FIG. 2, the control pressure P of each hydraulic cylinder 18FL to 18RR becomes a predetermined offset pressure P ₀ .

On the other hand, the control coefficient setting unit 58 of the controller 30 is shown in FIG.
And each control coefficient C according to the relational expressions shown in (b).
FL-CRR and KFL-KRR are set and supplied to the control force calculation unit 54. Then, assuming that the vehicle speed at the present time is in the vehicle speed range where the pitch resonance is likely to occur on the spring, the control coefficient setting unit 58 sets the control coefficients CFL to CRR and KFL to KRR to set the target control force FFL on the front wheel side. Although the FFR tends to advance and the target control forces FRL and FRR on the rear wheel side tend to lag, since the vertical acceleration detection values X _g FL to X _g RR are zero in the first place, the control force is applied to the active suspension 16. Does not occur.

From this state, as shown in FIG. 7 (a), when the half cycle of the unevenness on the road surface becomes or substantially matches the wheel base, the front wheel 10F and the rear wheel 1
Since vertical vibrations of opposite phases are input to 0R, if they are transmitted to the spring as they are, pitch vibration on the spring will occur and pitch resonance will occur. However, in the present embodiment, when it is determined based on the vehicle speed detection value V that the vehicle is in a vehicle speed range where pitch resonance is likely to occur, the control coefficients CFL to CRR are irrespective of whether pitch resonance occurs. And KFL-KRR are set as described above.

Therefore, vertical vibration is generated in each wheel member according to the unevenness of the traveling road surface, and the vertical vibration is supplied to the controller 30 as the vertical acceleration detection values X _g FL to X _g RR.
By the integrator 50 and 52 vertical velocity X _r FL~X _r RR and vertical displacement X _d FL~X _d RR is calculated, to their vertical velocity X _r FL~X _r RR and vertical displacement X _d FL~X _d RR Accordingly, when the target control forces FFL to FRR are calculated by the control force calculation unit 58, the control coefficients CFL and CFR are set to be relatively large on the front wheel side and the control coefficients KFL and KFR are set to be small on the rear wheel side. Since CRR is set to be small and control coefficients KRL and KRR are set to be large, hydraulic cylinders 18FL, 1 on the front wheel side are set.
The control force F as shown in FIG. 8A is generated in 8FR, and the control force F as shown in FIG. 8B is generated in the hydraulic cylinders 18RL, 18RR on the rear wheel side. FIG.
(A), the spring abscissa vertical displacement X _d under spring, and the vertical axis a vertical velocity X _r of the unsprung, among the arrow, F _L is inputted from the road surface under the spring (b) Lower vibration vector, F
_U is a vector of the transmission force transmitted from the unsprung part to the sprung part, and F _u = F _L + F.

The control force F on the front wheel side is the vertical speed X
_Since the reverse phase components of _r FL and X _r FR are the main components, their phases tend to lead. Then, transmission force F _U for the front wheel obtained by subtracting the control force F from the unsprung vibration F _L will be delayed relative to unsprung vibration F _L. On the contrary, the control force F on the rear wheel side has a tendency that its phase is delayed because the reverse phase components of the vertical displacements X _d FL and X _d FR are the main components. Then
Transmission force F _U of the rear wheels obtained by subtracting the control force F from the unsprung vibration F _L will proceed relative to unsprung vibration F _L.

As a result, as shown in FIG. 7A, the phase difference between the transmission forces on the front wheel side and the rear wheel side, which were in opposite phases according to the road surface unevenness, decreases, and the transmission forces approach the in-phase input. The pitch vibration itself on the spring is suppressed, and it becomes difficult for pitch resonance to occur. Next, as shown in FIG. 7 (b), when the cycle of the unevenness on the road surface becomes sufficiently longer than that of the wheel base, and when the vehicle is traveling at high speed, the front wheel 10F and the rear wheel 10R have substantially the same vertical vibration. Therefore, if this is transmitted to the spring as it is, it will become bounce vibration on the spring and bounce resonance will occur.

However, in the present embodiment, when it is determined that the vehicle speed range is in which bounce resonance is likely to occur based on the vehicle speed detection value V, each control coefficient is irrespective of whether or not bounce resonance occurs. CFL-CRR and KFL-KRR are set as described above. Therefore, vertical vibration is generated in each wheel side member according to the unevenness of the traveling road surface, and the vertical vibration is supplied to the controller 30 as vertical acceleration detection values X _g FL to X _g RR, and the vertical speed X is increased by the integrators 50 and 52. _r FL to X _r
RR and vertical displacement X _d FL~X _d RR is calculated, the target control force by the control force calculating unit 58 according to their vertical velocity X _r FL~X _r RR and vertical displacement X _d FL~X _d RR FFL~FRR Is calculated, the control coefficients CFL and CFR are set small and the control coefficients KFL and KFR are set large on the front wheel side, and the control coefficients CRL and CRR are set large and the control coefficients KRL and KRR are set small on the rear wheel side. Therefore, the front side hydraulic cylinder 18F
The control force F as shown in FIG. 9A is generated in L and 18FR, and the control force F as shown in FIG. 9A is generated in the hydraulic cylinders 18RL and 18RR on the rear wheel side.
The control force F as shown in (b) is generated. The meanings of the reference numerals in FIGS. 9A and 9B are the same as those in FIG.
This is similar to the case of (a) and (b).

The control force F on the front wheel side is the vertical displacement X
_Since the opposite phase components of _d FL and X _d FR are the main components, their phases tend to be delayed. Then, the front wheel side transmission force F _U
It will proceed with respect to unsprung vibration F _L. On the contrary, the control force F on the rear wheel side has a main component of a reverse phase component of the vertical velocities X _r FL and X _r FR, and therefore its phase tends to advance. Then, the transmission force F _U on the rear wheel side lags behind the unsprung vibration F _L.

As a result, as shown in FIG. 7B, the phase difference between the transmission forces on the front wheel side and the rear wheel side, which are in phase according to the road surface unevenness, expands, and these transmission forces are input to the opposite phase. Approaching,
The bounce vibration on the spring itself is suppressed, and it becomes difficult for bounce resonance to occur. In fact, of the transmission force F _U that remains without being canceled by the control force F, a part of the vibration input having a relatively low frequency is the pressure control valves 20 FL to 20 FL.
It is absorbed by the pressure adjustment of the pressure chamber L by RR, and part of the vibration input of relatively high frequency is absorbed by the movement of hydraulic oil between the pressure chamber L and the accumulator 34 through the throttle valve 32. Not all of _U is transmitted on the spring.

As described above, in the present embodiment, the pitch vibration itself is reduced by reducing the phase between the front and rear wheels of the transmission force from the road surface to the spring in the low speed range where the pitch resonance is likely to occur on the spring. However, in the high-speed range where bounce resonance is likely to occur on the spring, the bounce vibration itself occurs on the spring by expanding the phase between the front and rear wheels of the transmission force from the road surface to the spring. Therefore, a large control force F that can completely cancel the unsprung vibration F _L is used.
It is not necessary to generate the fuel consumption, and the energy consumption is reduced, which leads to the improvement of fuel consumption.

Here, in the present embodiment, the vertical acceleration sensors 28FL to 28RR, the integrators 50 and 52 correspond to the unsprung vibration detecting means, and the control force calculating section 54 and the driver circuit 56 correspond to the controlling means. The vehicle speed sensor 29 corresponds to the vehicle speed detection means, the control coefficient setting unit 58 corresponds to the phase characteristic control means, and the functions for the control coefficients CFL to CRR and KFL to KRR are set according to the vehicle speed detection value V in the control coefficient setting unit 58. Selection processing corresponds to the pitch resonance determination means and the bounce resonance determination means, the vertical acceleration sensors 28FL to 28RR and the integrator 50 correspond to the unsprung vertical speed detection means, and the vertical acceleration sensors 28FL to 28RR, the integrator 50 and Reference numeral 52 corresponds to the unsprung vertical displacement detecting means.

In the first embodiment, the control coefficient setting unit 58 incorporates the vehicle speed detection value V into a function as shown in FIGS. 6A and 6B to obtain the control coefficients CFL to CFL.
Although RR and KFL to KRR are obtained, the present invention is not limited to this. For example, the relationship between the vehicle speed detection value V and the control coefficients CFL to CRR and KFL to KRR as shown in FIG. According to the vehicle speed detection value V, the control coefficients CFL-CRR and KFL-
You may make it set KRR. However, the control coefficients CFL to CRR and KFL to KRR shown in FIG. 10 are calculated by multiplying the control coefficients CFL to CRR and KFL to KRR by the actual damping constant C ₀ and spring constant K ₀ at the positions of the wheels 10FL to 10RR of the active suspension 16. The value is used for the calculation in the unit 54. Further, each control coefficient CFL to CRR and KFL to
The value of KRR is not limited to the value shown in the present embodiment, but the spring constant of the active suspension 16, the damping constant, the capacities of the hydraulic cylinders 18FL to 18RR, the response characteristics of the entire control system, and the required control. It is appropriately selected according to the vibration effect and the like.

11 and 12 are views showing the main part of the second embodiment of the present invention. Since the overall configuration of this embodiment is the same as that of the first embodiment, its illustration and detailed description are omitted. That is, this even in the second embodiment, the vertical acceleration detection value as in the first embodiment X _g FL~X _g RR is detected, the vertical acceleration detection value X _g FL~X _g Vertical speed X _r FL
˜X _r RR and vertical displacement X _d FL ˜X _d RR are calculated. Then, in the first embodiment, by incorporating the vertical velocity X _r FL~X _r RR and vertical displacement X _d FL~X _d RR as they unsprung vibration function as described above (1) Although the target control forces FFL to FRR were to be obtained, in the second embodiment, the vertical speed X
and it obtains the target control force FFL~FRR with reference to a predetermined table on the basis of the _{r FL~X r} RR and vertical displacement X _d FL~X _d RR.

[0068] That is, advance to create a table similar to that target control force FFL~FRR is obtained in the case of using a function preliminarily, vertical velocity X _r FL~X _r RR and vertical displacement X _d FL~
Target control force FFL to FR by referring to the table based on X _d RR
R is obtained, and command currents IFL-IRR corresponding to the target control forces FFL-FRR are output to the pressure control valves 20FL-20RR.

The table for obtaining the target control forces FFL to FRR is created at least independently for the front and rear wheels, and is created for each vehicle speed over the entire vehicle speed range. For example, the example shown in FIG. 10A is a part of a table for obtaining the target control force FFL corresponding to the front left wheel when the vehicle speed is 40 km / h, and the example shown in FIG. Is a part of a table for obtaining a target control force FFL corresponding to the front left wheel when is 60 km / h. FIG.
The target control force FFL shown in 0 (a) and (b) is the damping constant C
₀ = 2000 [N / m / s], spring constant K ₀ = 2000
It is a value obtained as 0 [N / m].

FIG. 12 is a flow chart showing an outline of the processing of the controller 30 in the present embodiment. After the processing of steps 101 to 103 is carried out as in the first embodiment, the processing shifts to step 201. , processing by referring to the table based on the vertical velocity X _r FL~X _r RR and vertical displacement X _d FL~X _d RR reads the target control force FFL~FRR is executed. Then, in step 106, the command currents IFL-IRR are output to the pressure control valves 20FL-20RR.

With such a configuration, the controller 3
0 is adapted to select the table corresponding to the vehicle speed detection value V independently for each wheel or front and rear wheels, and the control force calculation unit 54 of the controller 30 selects the target control force FFL ... FRR will be read. Therefore, also in the present embodiment, the same operational effect as in the first embodiment can be obtained.

Moreover, in the present embodiment, since the target control forces FFL to FRR are stored in the table, a fine control coefficient which is difficult to define as a function as in the first embodiment. Even with CFL to CRR and KFL to KRR, there is an advantage that setting can be performed without trouble. Here, in the present embodiment, the processing of step 201 of selecting a table based on the vehicle speed detection value V in the controller 30 corresponds to the phase characteristic control means.

FIG. 13 shows the third embodiment of the present invention, and is a block diagram showing the functional configuration of the controller 30. The overall configuration of this embodiment is the same as that of the first embodiment described above, and therefore its illustration and detailed description are omitted. The same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof will not be repeated.

That is, the controller 30 of the present embodiment
Are each vertical acceleration detection value X _g FL~X _g RR have a filter coefficient variable filter 60 for calculating a target control force FFL~FRR by filtering each goal the filter 60 is calculated The control forces FFL to FRR are supplied to the driver circuit 56, and the driver circuit 56 generates the command currents IFL to IRR to generate the pressure control valves 20FL to 20FL.
It will be supplied to the RR. As the filter 60, for example, a secondary filter represented by the following (3) is applied.

-AiTi / {s (1 + Tis)} (3) Note that i = FL to RR, where Ai and Ti are filter coefficients,
s is a Laplace operator, and the phase characteristic of this secondary filter becomes as shown in FIG. 14 according to the filter coefficient T _i . By the way, since the phase of the vertical velocity with respect to the vertical acceleration under the spring is −90 degrees and the phase of the vertical displacement with respect to the vertical acceleration under the spring is −180 degrees, the target control forces FFL to FRR of The filter coefficient T _i may be determined so that the desired phase characteristic can be obtained.

Then, the controller 30 determines the filter coefficient AFL used by the filter 60 based on the detected vehicle speed value V.
.About.ARR and TFL.about.TRR are set at least independently for the front and rear wheels. However, the filter coefficients AFL to ARR in the filter coefficient setting unit 62 are
And setting of TFL to TRR and supply to the filter 60 are
The calculation is performed prior to the calculation of the target control forces FFL to FRR in the filter 60.

Here, in principle, the filter coefficient setting section 62 determines that the value (V / 2L) obtained by dividing the vehicle speed detection value V by twice the wheel base L matches the sprung pitch resonance frequency of this vehicle, or If they substantially match, it is determined that pitch resonance is likely to occur on the spring, and the phase characteristic of the filter for calculating the target control forces FFL and FFR on the front wheel side of the filter 60 advances, and the target control on the rear wheel side proceeds. The filter characteristics AFL to ARR and TFL to TRR are set such that the phase characteristics of the filter for calculating the forces FRL and FRR are delayed and supplied to the filter 60, while the vehicle speed detection value V is divided by the wheel base L (V / When L) is sufficiently large (for example, 10 to 15 times or more) with respect to the sprung bounce resonance frequency of this vehicle, it is determined that bounce resonance is likely to occur on the spring,
Among the filters 60, the phase characteristics of the filter for calculating the target control forces FFL, FFR on the front wheel side are delayed, and the phase characteristics of the filter for calculating the target control forces FRL, FRR on the rear wheel side are advanced. TFL to TRR are set and supplied to the filter 60.

Specifically, assuming that the vehicle specifications are the same as those in the first embodiment, the filter coefficient setting unit 6
No. 2 sets the filter coefficients AFL to ARR and TFL to TRR with the tendency shown in FIGS. 15 (a) and 15 (b). The relations shown in FIGS. 15 (a) and 15 (b) can be expressed by the following equations in different cases.

[0079] 0 <V <25km / h: AFL, AFR = - (K 0 -C 0) V / 50 + (K 0 +
_{C 0) / 2 ARL, ARR} = (K 0 -C 0) V / 50 + (K 0 + C 0)
/ 2 TFL, TFR = -0.12V / 25 + 0.15 TRL, TRR = 0.15V / 25 + 0.15 25 <V <50km / h: AFL, AFR = C 0 ARL, ARR = K 0 TFL, TFR = 0 .03 TRL, TRR = 0.3 50 < V <100km / h: AFL, AFR = (K 0 -C 0) V / 50-K 0 + 2C 0 ARL, ARR = - (K 0 -C 0) V / 50 + 2K ₀ −C ₀ TFL, TFR = 0.27V / 50−0.24 TRL, TRR = −0.27V / 50 + 0.57V> 100km / h: AFL, AFR = K ₀ ARL, ARR = C ₀ TFL, TFR = 0.3 TRL, TRR = 0.03 Then, the outline of the processing of the controller 30 in the present embodiment is summarized in a flowchart as shown in FIG. That is, as in the first embodiment, after the processing of step 101 is performed, the process proceeds to step 301, where the filter coefficient setting unit 62 determines the filter coefficients AFL to ARR, TFL
~ TRR is set, then the process proceeds to step 302, and the filter 60 uses the filter coefficients AFL to ARR and TFL to TRR set in step 301 and the filter of (3) above to detect the vertical acceleration value X _g FL. .About.X _g RR are filtered to calculate target control forces FFL to FRR. Then, in step 106, the driver circuit 56 outputs the command currents IFL to IRR to the pressure control valves 20FL to 20RR.

Even with such a construction, in the low speed range where pitch resonance is likely to occur on the spring, the target control force F on the front wheel side is obtained.
As FL and FFR phases advance, the target control force F on the rear wheel side
While the phases of RL and FRR are delayed, in the high speed range where bounce resonance is likely to occur on the spring, the target control force FFL, FFR on the front wheel side
Is delayed and the target control force FRL, F on the rear wheel side is
Since the phase of RR is advanced, the same operational effect as in the first embodiment can be obtained.

Moreover, in the present embodiment, the filter 60
Is used to calculate the target control forces FFL to FRR, and the characteristic of the filter 60 is, for example, the controller 3
Since it can be easily set according to the characteristics of the control system such as the overall calculation time and the response characteristics of the hydraulic cylinders 18FL to 18RR, it is relatively easy to optimize the control according to the device configuration. There is also an advantage.

Here, in the present embodiment, the vertical acceleration sensors 28FL to 28RR correspond to the unsprung vibration detection means, the filter 60 and the driver circuit 56 correspond to the control means,
The filter coefficient setting unit 62 corresponds to the phase characteristic control means,
The process of selecting the function for the filter coefficients AFL to ARR and TFL to TRR in accordance with the vehicle speed detection value V in the filter coefficient setting unit 62 corresponds to the pitch resonance determining means and the bounce resonance determining means.

In the third embodiment, the secondary filter as shown in (3) above is used as the filter 60, but a higher order filter may be used.
In addition, in the third embodiment, the vertical acceleration detection values X _g FL to X _g RR are used as the vertical vibration under the spring.
The invention is not limited thereto, for example by integrating the vertical acceleration detection value X _g FL~X _g RR vertical velocity X _r FL~X _r
Using the RR as a vertical vibration, the vertical velocity X _r FL~X _r RR
May be appropriately filtered to calculate the target control forces FFL to FRR. However, in that case, (3) above
Instead of the secondary filter as shown in (1), for example, a primary filter as shown in the following (4) is used.

-AiTi / (1 + Tis) (4) Then, in the third embodiment, as shown in FIG.
Although the vehicle speed detection value V is taken into the function as shown in (b) to obtain the filter coefficients AFL to ARR and TFL to TRR, the present invention is not limited to this. For example, the last of the first embodiment described above. As described with reference to FIG. 10, each filter coefficient A is referred to by referring to the table according to the vehicle speed detection value V.
You may make it set FL-ARR and TFL-TRR.

FIG. 17 is a diagram showing the fourth embodiment of the present invention and is a block diagram showing the functional configuration of the controller 30. The overall configuration of this embodiment is the same as that of the first embodiment described above, and therefore its illustration and detailed description are omitted. The same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof will not be repeated.

That is, in the controller 30 of the present embodiment, the vertical acceleration detection values X _g FL, X _g FR detected by the front wheel vertical acceleration sensors 28 FL, 28 FR and the vehicle speed sensor 29 are used.
However, unlike the first embodiment, the vertical acceleration sensors 28RL and 28RR on the rear wheel side are omitted, and therefore the vehicle speed detection value V detected by the rear wheel side is omitted. The vertical acceleration detection values X _g RL and X _g RR are not supplied to the controller 30.

The controller 30 has a delay circuit 64 in which the delay time is set according to the vehicle speed detection value V and the wheel base L of the vehicle. This delay circuit 64
Is the delay time τ (corresponding to the difference in passing time between the vertical acceleration detection values X _g FL and X _g FR on the front wheel side at an arbitrary point on the traveling road surface of the front wheels and the rear wheels, which is known from the vehicle speed detection value V and the wheel base L. = L / V), the vertical acceleration of the unsprung portion on the rear wheel side is estimated, and the estimated value is supplied to the integrator 50 as the vertical acceleration detection values X _g RL, X _g RR on the rear wheel side. It is like this. In other words, when the vehicle is traveling in a straight line, the loci of the front wheels and the loci of the rear wheels substantially coincide with each other, so there is a time difference between the unsprung vibration on the front wheel side and the unsprung vibration on the rear wheel side. They can be regarded as almost the same except for. Therefore, the vertical acceleration detection values on the front wheel side X _g FL, X _g FR
If the delay processing is performed, the vertical acceleration detection value X _g RL, on the rear wheel side,
X _g RR can be estimated almost accurately.

Here, the outline of the processing of the controller 30 in the present embodiment is summarized in a flowchart as shown in FIG.
As shown in FIG. That is, in step 401,
The vertical acceleration detection values X _g FL, X _g FR and the vehicle speed detection value V are read, then the routine proceeds to step 402, where the delay circuit 6
4 sets the delay time τ based on the vehicle speed detection value V and the wheel base L, and then proceeds to step 403, where the delay circuit 64 delays the vertical acceleration detection values X _g FL, X _g FR by the delay time τ. By processing, the vertical acceleration detection values X _g RL and X _g RR are estimated and calculated. After that, the same processing as steps 102 to 106 in the first embodiment is executed.

Therefore, even in the fourth embodiment,
The same effects as those of the first embodiment can be obtained. In addition, the vertical acceleration sensors 28RL and 28RR on the rear wheel side can be omitted, which is advantageous in terms of cost. Further, since the vertical acceleration detection values X _g RL, X _g RR on the rear wheel side can be obtained in advance, the time delay due to the calculation time in the controller 30 and the response characteristics of the hydraulic cylinders 18RL, 18RR can be compensated. Another advantage is that the damping control on the rear wheel side can be performed with higher accuracy. That is, as disclosed in, for example, Japanese Patent Application Laid-Open No. 5-319067 previously proposed by the present applicant, the calculation time in the controller 30 and the response delay time of the hydraulic cylinders 18RL and 18RR are approximated as dead time τ ′, If the delay time .tau. In the delay circuit 64 is .tau. = L / V-.tau. ', The response delay time and the like will be compensated.

In this embodiment, the vertical acceleration sensors 28FL and 28FR, the integrators 50 and 52, and the delay circuit 6 are used.
Reference numeral 4 corresponds to the vertical vibration detection means, and the delay circuit 64 corresponds to the rear wheel side unsprung vibration estimation means. FIG. 19 is a diagram showing the fifth embodiment of the present invention and is a block diagram showing a functional configuration of the controller 30. The overall configuration of this embodiment is the same as that of the first embodiment described above, and therefore its illustration and detailed description are omitted. The same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof will not be repeated.

That is, in this embodiment, the vertical acceleration sensors 28FL to 28RR for detecting the unsprung vertical acceleration are omitted, and therefore the controller 30 is supplied with the vertical acceleration detection values X _g FL to X _g RR. Not like that. On the other hand, in the present embodiment, the sprung vertical acceleration sensors 66FL to 66RR for detecting the vertical acceleration at the positions where the hydraulic cylinders 18FL to 18RR of the vehicle body side member 14 are disposed.
And stroke sensors 68FL to 68RR that detect suspension strokes at the positions of the wheels 10FL to 10RR.
And are provided separately.

The vertical acceleration sensors 66FL to 66RR detect the vertical acceleration at each installation position, and the vertical acceleration sensor 2
Similar to 8FL-28RR, positive for upward acceleration,
In the case of downward acceleration, the negative vertical acceleration detection value B _g FL
~ B _g RR is generated and supplied to the controller 30. In addition, the stroke sensors 68FL to 68RR detect the suspension stroke at each disposition position, and a positive stroke detection value when the suspension stroke changes from the neutral position to the contracting direction, and a negative stroke detection value when the suspension stroke changes to the extending direction. SFL to SRR are generated and supplied to the controller 30. The vehicle speed detection value V is also supplied to the controller 30.

[0093] Then, the controller 30 includes an integrator 70 which integrates the vertical acceleration detection value B _g FL~B _g RR supplied for calculating a vertical velocity B _r FL~B _r RR sprung supplied A differentiator 72 that differentiates the stroke detection values S FL to S RR to calculate stroke speeds S _r FL to S _r RR, and an integrator 7.
0 vertical velocity X _r FL~ under spring in addition to the wheel position and a vertical velocity B _r FL~B _r RR stroke speed differentiator 72 calculates S _r FL~S _r RR sprung computed X _r
And an adder 74 that calculates RR.

That is, Japanese Patent Application Laid-Open No. Hei.
As disclosed in detail in Japanese Patent Publication No. 319067,
Vertical speed B _r FL to B _r RR on the spring and stroke displacement S
and _{r FL~S r} RR, between the vertical velocity X _r FL~X _r RR unsprung, since relation _{X r i = B r i +} S r i holds, output intact unsprung adder 74 it can be used as a vertical velocity X _r FL~X _r RR.

[0095] Therefore, supplies the vertical velocity X _r FL~X _r RR that adder 74 is determined in the control force calculating section 54 integrates the vertical velocity X _r FL~X _r RR by the integrator 52 control force calculating unit 5 the vertical displacement X _d FL~X _d RR obtained
If it is supplied to No. 4, it is possible to obtain the same effect as that of the first embodiment. Here, a summary of the processing of the controller 30 in the present embodiment is summarized in a flowchart as shown in FIG. That is, step 501
In the vertical acceleration detection value B _g FL~B _g RR, reads a stroke detected value SFL~SRR and the vehicle speed detection value V, then the process proceeds to step 502, the vertical acceleration detection value integrator 70 B _g FL~B _g RR Vertical speed B _r F
L to B _r RR is calculated, and the process proceeds to step 503. The differentiator 72 differentiates the stroke detection values S FL to S RR to calculate the stroke speed S _r FL to S _r RR, and then the process proceeds to step 504. , the adder 74 is vertical velocity B _r FL~B
by adding the _r RR and the stroke velocity S _r FL~S _r RR for calculating a vertical velocity X _r FL~X _r RR. After that, the same processing as steps 103 to 106 of the first embodiment is executed.

Moreover, in the present embodiment, it is not necessary to provide an acceleration sensor on the wheel side member 12 close to the wheels 10FL to 10RR in a harsh environment where the vibration input is transmitted from the road surface with almost no reduction. Since the vertical acceleration sensors 66FL to 66RR to be attached are cheaper than the vertical acceleration sensors 28FL to 28RR to be attached under the spring, there is also an advantage that the cost can be reduced without impairing reliability and durability.

Here, in this embodiment, the vertical acceleration sensors 66FL to 66RR and the stroke sensors 68FL to 68R.
R, integrator 70, differentiator 72, adder 74 and integrator 5
2 corresponds to the unsprung vibration detecting means. In this embodiment, the vertical acceleration sensors 66FL to 66RR are arranged at four positions corresponding to the hydraulic cylinders 18FL to 18RR, but if the vehicle body side member 14 is considered to be a rigid body, Vertical acceleration sensors are provided at arbitrary three positions on the side member 14, and outputs of the three vertical acceleration sensors are appropriately interpolated to detect vertical acceleration on the spring corresponding to the placement positions of the hydraulic cylinders 18FL to 18RR. The value may be obtained. Further, the vertical acceleration sensors 66FL and 66FR and the stroke sensors 68FL and 68FR on the rear wheel side are omitted, and the fourth acceleration sensor
A delay circuit similar to that of the embodiment is provided, and the delay circuit delays the vertical velocities X _r FL, X _r FR of the front wheels to obtain the vertical velocities X _r RL, X _r RR of the rear wheels. You may ask. Furthermore, stroke sensors 68FL to 68RR
Instead of this, a stroke speed sensor may be provided, in which case the differentiator 72 becomes unnecessary.

FIG. 21 is a diagram showing the sixth embodiment of the present invention and is a block diagram showing the functional configuration of the controller 30. As shown in FIG. The overall configuration of this embodiment is the same as that of the first embodiment described above, and therefore its illustration and detailed description are omitted. Moreover, the same components as those in the above-described respective embodiments are designated by the same reference numerals, and the duplicate description thereof will be omitted.

That is, in the present embodiment, the vertical acceleration sensors 28FL to 28RR provided in the first embodiment and the vertical acceleration sensor 6 provided in the fifth embodiment.
6FL to 66RR and stroke sensors 68FL to 68RR are omitted. On the other hand, in the present embodiment, as shown in FIG. 22A which is a schematic side view of the vehicle, each front wheel 10
Road surface sensors 76L and 76R that detect the distance between the vehicle body (under spring) and the road surface in front of FL and 10FR, respectively, and a vertical acceleration sensor 78L that detects vertical acceleration at the positions where the road surface sensors 76L and 76R are arranged.
And 78R are provided separately.

Each of the road surface sensors 76L and 76R is, for example, a distance sensor using ultrasonic waves, detects the distance between the vehicle body and the road surface at each installation position, and detects the distance with a voltage value corresponding to the distance. HL and HR are generated and supplied to the controller 30. Further, the vertical acceleration sensors 78L and 78R detect vertical accelerations at the respective installation positions, and the vertical acceleration sensors 28FL to 28RR.
Similarly, in the case of upward acceleration, positive vertical acceleration detection values B _g L and B _g R that are positive in the case of downward acceleration and negative in the case of downward acceleration are generated and supplied to the controller 30.
The vehicle speed detection value V is also supplied to the controller 30.

Here, the positions of the road surface sensors 76L and 76R and the vertical acceleration sensors 78L and 78R, and the front wheel 1
The distances between 0FL, 10FR, the rear wheels 10RL, 10RR and the road surface grounding points are L ₁ and L ₂ , respectively. The distances L ₁ and L ₂ are illustrated in FIG. 22B which is a bottom view of the left half of the vehicle. And the controller 30
Is an integrator 70 that integrates the supplied vertical acceleration detection values B _g L and B _g R to calculate vertical velocities B _r L and B _r R.
If, differentiator differentiates the distance detection value HL and HR are supplied to calculating the relative velocity H _r L and H _r R Vehicle body road 72
And the vertical velocities B _g L and B _g R and the relative velocity H between the vehicle body road surfaces.
and an adder 74 that adds _r L and H _r R to calculate road surface displacement speeds Z _r L and Z _r R at the positions where the road surface sensors 76 L and 76 R are arranged.

Further, the controller 30 delays the road surface displacement speeds Z _r L and Z _r R by the delay time τ ₁ (= L ₁ / V) corresponding to the distance L ₁ and the detected vehicle speed value V, the front wheels 10FL, delay circuit obtains a road surface displacement speed at 10FR position, and outputs the sought road surface displacement velocity vertical velocity X _r FL under the front wheel side of the spring, as X _r FR 80F
And the road surface displacement velocities Z _r L and Z _r R are delayed by a delay time τ ₂ (= L ₂ / V) corresponding to the distance L ₂ and the vehicle speed detection value V, so that the rear wheels 10RL and 10RR are positioned. seeking road displacement speed has its vertical velocity of the unsprung rear wheel side road surface displacement velocity obtained X _r RL, a delay circuit 80R which outputs the X _r RR, the.

The vertical velocities X _r FL to X _r RR obtained by the delay circuits 80 F and 80 _R are supplied to the control force calculator 54, and the vertical velocities X _r FL to X _r RR are supplied to the integrator 52. vertical displacement X _d FL~X _d RR obtained by integration is also adapted to supply to the control force calculating unit 54. In other words, the front wheels 10FL, the unevenness of the front road surface than 10FR, road surface sensor 76L, the output of the 76R and the vertical acceleration sensors 78L, can be obtained from the output of 78R, based on the vehicle speed detection value V and the distance L ₁ delay time tau ₁ delayed by the front wheels 10FL, 10FR passes over the irregularity, the rear wheels 10RL delayed by a delay time tau ₂ based on the vehicle speed detection value V and the distance L _2, 10RR passes over the unevenness, moreover Since each wheel-side member 12 moves up and down due to the unevenness of the traveling road surface, each wheel 10 calculated by the delay circuits 80F and 80R.
An estimate of the irregularities of the road surface at FL~10RR position, it is possible to vertical velocity X _r FL~X _r RR as unsprung vibration.

Here, the outline of the processing of the controller 30 in the present embodiment can be summarized in a flowchart as shown in FIG.
As shown in FIG. That is, in step 601, the vertical acceleration detection values B _g L and B _g R and the distance detection values HL and HR are detected.
And the vehicle speed detection value V are read, and then step 602
, The integrator 70 detects the vertical acceleration detection values B _g L and B
_The vertical speeds B _r L and B _r R are calculated by integrating _g R, respectively, and then the process proceeds to step 603, where the differentiator 72 differentiates the distance detection values HL and HR, respectively, and the relative speed H _r L between the vehicle body road surfaces. And H _r R are respectively calculated, and then the process proceeds to step 604, where the adder 74 causes the vertical speed B _g L,
The road surface displacement velocities Z _r L and Z _r R are calculated by adding B _g R and the vehicle body road surface relative velocities H _r L and H _r R.

Then, the processing shifts to step 605, the delay circuits 80F and 80R calculate the delay times τ ₁ and τ ₂ based on the vehicle speed detection value V and the distances L ₁ and L ₂ , and then the processing shifts to step 606 to delay. The circuits 80F and 80R delay the road surface displacement velocities Z _r L and Z _r R by the delay times τ ₁ and τ ₂ to calculate vertical velocities X _r FL to X _r RR. After that, the same processing as steps 103 to 106 in the first embodiment is executed.

Therefore, even in the sixth embodiment,
The same effects as those of the first embodiment can be obtained. Also, in this embodiment, the wheel 10FL which is used in a severe environment
Since it is not necessary to provide an acceleration sensor on the wheel-side member 12 close to 10 RR, there is also an advantage that cost can be reduced without impairing reliability and durability. Furthermore, since it is possible to obtain the vertical velocity X _r FL~X _r RR at each wheel position in advance, can be time delay compensation due to the response characteristics of the operation time and the hydraulic cylinders 18FL~18RR in the controller 30, each wheel There is also an advantage that the vibration suppression control at the position can be performed with higher accuracy. That is, as in the fourth embodiment, the dead time τ ′ is calculated, and the delay circuits 80F and 80
If the delay times τ ₁ and τ ₂ in R are τ ₁ = L ₁ / V−τ ′ τ ₂ = L ₂ / V−τ ′, the response delay time and the like will be compensated.

Here, in the present embodiment, the road surface sensor 7
6L, 76R, vertical acceleration sensors 78L, 78R, integrator 70, differentiator 72, adder 74, delay circuits 80F, 8
The 0R and the integrator 52 correspond to the unsprung vibration detecting means, and the road surface sensors 76L and 76R and the vertical acceleration sensors 78L and 7R.
The 8R, the integrator 70, the differentiator 72 and the adder 74 correspond to the road surface unevenness detecting means, and the delay circuits 80F and 80R and the integrator 52 correspond to the unsprung vibration estimating means.

In the sixth embodiment, the vertical acceleration sensors 68L and 68R are arranged at two locations corresponding to the road surface sensors 76L and 76R, respectively. If it cannot be installed at the same position as 76L, 76R, the road surface sensor 7
6L and 76R are fixed members, and vertical acceleration sensors are arranged at arbitrary three positions on the same plane, and outputs of the three vertical acceleration sensors are appropriately interpolated to calculate the arrangement of the road surface sensors 76L and 76R. The vertical acceleration detection value corresponding to the installation position may be obtained.

24 to 26 are diagrams showing simulations carried out in connection with the present invention. FIG. 24 is a conceptual diagram of a vehicle model used in the simulations, FIGS. 25 and 26.
[Fig. 4] is a waveform diagram showing a simulation result. In addition, the model used for the simulation excludes the rolling motion of the vehicle and considers only the vibrations in the bounce direction and the pitch direction.

25, it is assumed that the vehicle is traveling in a vehicle speed range where pitch resonance is likely to occur in the vehicle body.
FIG. 26 assumes that the vehicle is traveling in a vehicle speed range where bounce resonance is likely to occur in the vehicle body. In addition, FIG.
Is the road surface displacement, (b) is the pitch angular acceleration, and (c) is the pitch angular acceleration.
Indicates the front wheel control force, and (d) indicates the rear wheel control force. Similarly, FIG. 26 (a) shows the road surface displacement as shown in FIG.
Indicates bounce acceleration, (c) indicates front wheel control force, and (d) indicates rear wheel control force.

Furthermore, control coefficients CFL to CRR and KFL to K
The simulation result when RR is fixed to the damping constant C ₀ and the spring constant K ₀ of the suspension (comparative example) is shown in FIG.
5 and FIG. 26 are shown by solid lines, and control coefficients CFL to CRR and K
Simulation results when FL to KRR are set based on the gist of the present invention (control example) are shown by broken lines in FIGS. 25 and 26. However, each control coefficient in the control example is the square integration value (= ∫ (FFL + FFR
+ FRL + FRR) ² dt) is set to be equivalent to the conventional example. That is, the energy consumptions of the comparative example and the control example are made equal and then the two are compared.

According to this simulation result, both pitch vibration and bounce vibration can be greatly reduced by adopting the present invention, although the energy consumption is equivalent (FIG. 25 (b), FIG. 26B). In other words, when the present invention is adopted, the energy consumption can be significantly reduced if the same damping effect as the conventional one is required.

In each of the above embodiments, by controlling the force generated in the hydraulic cylinders 18FL to 18RR based on the unsprung vibration, the vibration input from the traveling road surface to the unsprung part is transmitted to the sprung part. However, in addition to such a configuration, lateral acceleration and longitudinal acceleration generated in the vehicle are detected and roll displacement and pitch displacement on the spring are detected based on the detected acceleration values. By generating the effect on the hydraulic cylinders 18FL to 18RR, it is possible to prevent the sprung posture from changing due to factors other than road surface unevenness, and to ensure a better ride comfort.

In each of the above embodiments, the phase characteristics of both the front wheel side and the rear wheel side are controlled according to the detected vehicle speed V, but one of the phase characteristics is fixed,
Alternatively, only the other phase characteristic may be appropriately controlled.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an overall configuration of a first embodiment.

FIG. 2 is a graph showing a relationship between a command current and a control pressure.

FIG. 3 is a graph showing a relationship between vertical acceleration and a vertical acceleration detection value.

FIG. 4 is a block diagram showing a functional configuration of a controller.

FIG. 5 is a graph showing a relationship between a vehicle speed detection value and each control coefficient.

FIG. 6 is a flowchart showing an outline of processing according to the first embodiment.

FIG. 7 is a side view illustrating a relationship between a road surface shape and an input to a vehicle.

FIG. 8 is a vector diagram showing the relationship between unsprung vibration and control force.

FIG. 9 is a vector diagram showing the relationship between unsprung vibration and control force.

FIG. 10 is an explanatory diagram of a table for setting a control coefficient.

FIG. 11 is an explanatory diagram of a table according to the second embodiment.

FIG. 12 is a flowchart showing an outline of processing according to the second embodiment.

FIG. 13 is a block diagram showing a functional configuration of a controller according to a third embodiment.

FIG. 14 is a frequency characteristic diagram showing the phase characteristic of the filter.

FIG. 15 is a graph showing the relationship between vehicle speed detection values and filter coefficients.

FIG. 16 is a flowchart showing an outline of processing according to the third embodiment.

FIG. 17 is a block diagram showing a functional configuration of a controller according to a fourth embodiment.

FIG. 18 is a flowchart showing an outline of processing according to the fourth embodiment.

FIG. 19 is a block diagram showing a functional configuration of a controller according to a fifth embodiment.

FIG. 20 is a flowchart showing an outline of processing according to the fifth embodiment.

FIG. 21 is a block diagram showing a functional configuration of a controller according to a sixth embodiment.

FIG. 22 is an explanatory diagram of the arrangement position of the sensor.

FIG. 23 is a flowchart showing an outline of processing according to the sixth embodiment.

FIG. 24 is a conceptual diagram of a model used for simulation.

FIG. 25 is a waveform chart showing a simulation result.

FIG. 26 is a waveform diagram showing a simulation result.

[Explanation of symbols]

 10FL to 10RR Wheels 12 Wheel side member (Unsprung member) 14 Body side member (Spring member) 18FL to 18RR Hydraulic cylinder (Fluid pressure cylinder) 20FL to 20RR Pressure control valve 22 Hydraulic source 28FL to 28RR Vertical acceleration sensor 29 Vehicle speed sensor (Vehicle speed detecting means) 30 controller 50, 52 integrator 54 control force calculation unit 56 driver circuit 58 control coefficient setting unit 60 filter 62 filter coefficient setting unit 64 delay circuit 66FL to 66RR vertical acceleration sensor 68FL to 68RR stroke sensor 70 integrator 72 Differentiator 74 Adder 80F, 80R Delay circuit

Claims (13)

[Claims] 1. A fluid pressure cylinder inserted between a vehicle body and each wheel, a pressure control valve for controlling the working fluid pressure of each of these fluid pressure cylinders only in accordance with a command value, and each wheel of the vehicle body. Unsprung vibration detection means for detecting vertical vibration of the unsprung member at the position, and control means for generating the command value according to the unsprung vibration detection value detected by the unsprung vibration detection means and supplying it to the pressure control valve. And a vehicle speed detecting means for detecting the vehicle speed, and the front-rear wheel independent phase characteristic of the command value with respect to the unsprung vibration detection value according to the vehicle speed detection value detected by the vehicle speed detection means. An active suspension comprising: a phase characteristic control unit for controlling. 2. The phase characteristic control means is arranged such that the phase difference between the transmission force to the sprung member on the front wheel side and the transmission force to the sprung member on the rear wheel side deviates from the phase difference where sprung resonance is likely to occur. The active suspension according to claim 1, wherein the phase characteristic is controlled independently of the front and rear wheels. 3. The phase characteristic control means has pitch resonance determination means for determining whether or not pitch resonance is likely to occur on the spring based on the vehicle speed detection value, and the pitch resonance determination means is provided. When it is determined that the pitch resonance is likely to occur, at least one of the processing for advancing the phase characteristic on the front wheel side and the processing for delaying the phase characteristic on the rear wheel side is executed. Item 2. The active suspension according to Item 2. 4. The pitch resonance determining means determines that pitch resonance is likely to occur on the spring when a value obtained by dividing the vehicle speed detection value by twice the wheel base is equal to or substantially equal to the sprung pitch resonance frequency. The active suspension according to claim 3. 5. The unsprung vibration detection means detects unsprung vertical speed as vertical vibration of the unsprung member, and unsprung vertical displacement as vertical vibration of the unsprung member. Unsprung vertical displacement detection means,
The process of advancing the phase characteristic of the front wheel side in the phase characteristic control means is a process of generating the command value of the front wheel side with the antiphase component of the unsprung vertical velocity as a main component, and the phase characteristic The process for delaying the phase characteristic on the rear wheel side in the control means is a process for generating the command value on the rear wheel side by using a reverse phase component of the unsprung vertical displacement as a main component. Active suspension. 6. The phase characteristic control means has a bounce resonance determination means for determining whether or not bounce resonance is likely to occur on the spring based on the vehicle speed detection value, and the bounce resonance determination means is provided. When it is determined that the bounce resonance is likely to occur, at least one of the process of delaying the phase characteristic on the front wheel side and the process of advancing the phase characteristic on the rear wheel side is executed. The active suspension according to any one of claims 2 to 5. 7. The bounce resonance determining means determines that bounce resonance is likely to occur on the spring when a value obtained by dividing the vehicle speed detection value by the wheel base is sufficiently larger than the sprung bounce resonance frequency. Item 7. The active suspension according to item 6. 8. The unsprung vibration detection means detects unsprung vertical speed as vertical vibration of the unsprung member, and unsprung vertical displacement as vertical vibration of the unsprung member. Unsprung vertical displacement detection means,
The processing for delaying the phase characteristic on the front wheel side in the phase characteristic control means is processing for generating the command value on the front wheel side with the antiphase component of the unsprung vertical displacement as a main component, and the phase characteristic 8. The process of advancing the phase characteristic on the rear wheel side in the control means is a process of generating the command value on the rear wheel side by using an antiphase component of the unsprung vertical velocity as a main component. Active suspension. 9. The control means calculates the command value according to a predetermined function based on the unsprung vibration detection value, and the phase characteristic control means calculates the command value according to the vehicle speed detection value. 9. The active suspension according to claim 1, wherein the phase characteristic is controlled independently of the front and rear wheels by setting the front and rear wheels independently. 10. The control means calculates the command value by referring to a predetermined table based on the unsprung vibration detection value, and the phase characteristic control means responds to the vehicle speed detection value. 9. The active suspension according to claim 1, wherein the phase characteristic is controlled independently of the front and rear wheels by selecting the table independently of the front and rear wheels. 11. The control means is configured to filter the unsprung vibration detection value to calculate the command value, and the phase characteristic control means uses the filter coefficient in the filter processing for the front and rear wheels independently. The active suspension according to any one of claims 1 to 8, wherein the phase characteristic is controlled independently of the front and rear wheels by setting to (4). 12. The unsprung vibration detection means includes rear wheel unsprung vibration estimation means for delaying the unsprung vibration detection value on the front wheel side to estimate unsprung vibration on the rear wheel. The active suspension according to any one of claims 1 to 11, wherein an estimated value of the unsprung vibration on the wheel side is set as the detected value of the unsprung vibration on the rear wheel side. 13. The unsprung vibration detection means detects a road surface unevenness detecting means for detecting unevenness of a traveling road surface in front of a vehicle, and an unsprung vibration of a wheel position based on a road surface unevenness detection value detected by the road surface unevenness detection means. 12. The active suspension according to any one of claims 1 to 11, further comprising: an unsprung vibration estimating means for estimating the unsprung vibration, wherein the estimated value of the unsprung vibration is the unsprung vibration detected value.