JPH0832503B2 - Active suspension - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an active suspension, and more particularly to a fluid pressure cylinder arranged between a vehicle body side member and a wheel side member, and this fluid pressure cylinder. The present invention relates to an active suspension, which is provided with a pressure control valve for controlling the operating pressure according to a command value, and changes the command value according to the rolling motion of the vehicle.

[Conventional technology]

As a conventional vehicle active suspension, for example, one disclosed in Japanese Patent Application Laid-Open No. 1-95924 has been proposed by the present applicant.

This conventional active suspension includes a fluid pressure cylinder interposed between the vehicle body and each wheel, and a pressure control valve that controls the operating pressure of the fluid pressure cylinder according to a command value. Multiply the lateral acceleration and longitudinal acceleration by the control gain to calculate the command value for damping in each direction,
A method of outputting this command value to the pressure control valve is disclosed.

[Problems to be Solved by the Invention]

However, in such a conventional active suspension, the roll control is mainly performed according to the magnitude of the lateral acceleration generated in the vehicle body in order to prevent the posture change during turning of the vehicle. When the vehicle rolls due to a road surface irregularity while traveling straight ahead, there is an unsolved problem that the roll control cannot be accurately performed because the lateral acceleration is hardly detected.

The present invention has been made by paying attention to such an unsolved problem of the conventional technology, and even when a vehicle rolls due to road surface irregularity or the like in a straight traveling state, it is properly suppressed,
Stabilizing the vehicle posture is an issue to be solved.

[Means for solving the problem]

In order to solve the above problems, the invention of claim 1 is, as shown in FIG. 1 (a), a fluid pressure cylinder interposed between a vehicle body side member and a wheel side member for each wheel, and each fluid. A pressure control valve that individually controls the operating pressure of the pressure cylinder according to a command value, a vertical acceleration detection unit that detects vertical acceleration of the vehicle body on the right wheel side and the left wheel side, and each detection of the vertical acceleration detection unit. Vertical velocity calculating means for integrating the values to calculate the vertical velocity, roll angular velocity calculating means for calculating the roll angular velocity of the vehicle body based on the respective calculated values of the vertical velocity calculating means,
A gain setting means for setting a roll motion suppression gain that increases in accordance with an increase in the calculated value of the roll angular velocity calculation means, and a roll motion suppression gain set by the gain setting means and a vertical movement based on the detection value of the vertical acceleration detection means. And a command value calculation means for calculating the command value for suppressing the roll motion for each of the left and right wheels based on the speed.

The invention of claim 2 is, as shown in FIG. 1 (b), a fluid pressure cylinder provided for each wheel between a vehicle body side member and a wheel side member, and A pressure control valve that individually controls the operating pressure according to a command value, a vertical acceleration detection unit that detects the vertical acceleration of the vehicle body on the right wheel side and the left wheel side, and based on each detection value of this vertical acceleration detection unit Roll angle or angular acceleration calculation means for calculating the roll angle or angular acceleration of the vehicle body; gain setting means for setting a roll motion suppression gain that increases in accordance with an increase in the calculated value of the roll angle or angular acceleration calculation means; And a command value calculation unit that calculates the command value for suppressing the roll motion for each of the left and right wheels based on the roll motion suppression gain set by the gain setting unit and the detection value of the vertical acceleration detection unit.

[Action]

According to the first aspect of the invention, when the vehicle is in a constant speed straight ahead state, it is assumed that the vehicle body tries to roll by passing an irregular portion of the road surface and applying an external force in the vertical direction to the vehicle. At this time, the vertical acceleration detecting means detects each vertical acceleration occurring on the right wheel side and the left wheel side of the vehicle body and calculates the roll angular velocity based on each vertical acceleration, while the gain setting means responds to the increase of the roll angular velocity. An increasing roll motion suppression gain is set, a command value for suppressing the roll motion is calculated based on the roll motion suppression gain and the vertical velocity obtained by integrating the vertical acceleration, and the command value is given to each pressure control valve.
For this reason, the operating force of the fluid pressure cylinders for the left and right wheels attenuates the roll motion of the vehicle body, and in a traveling state in which little lateral acceleration occurs, rolling that is likely to occur due to road surface irregularities or the like is accurately suppressed. .

Further, in the invention of claim 2, the roll angle or the roll angular acceleration is calculated based on the vertical acceleration detection value of the vertical acceleration detecting means, and the roll motion suppression gain increases as the roll angle or the roll angular acceleration increases. Is set, a command value for suppressing the roll motion is calculated based on the roll motion suppression gain and the detection value of the vertical acceleration detecting means, and the command value is given to each pressure control valve. Similar to the invention, the rolling that is likely to occur due to road surface irregularities or the like is accurately suppressed.

〔Example〕

(First Embodiment) A first embodiment of the present invention will be described below with reference to FIGS. 2 to 6. The active suspension of this embodiment performs roll control, pitch control and bounce control of the vehicle body at the same time.

In FIG. 2, 10 is a vehicle speed member which is a suspension arm, 11FL to 11RR are front left to rear right wheels, and 12 is an active suspension.

The active suspension 12 includes a vehicle body side member 10 and wheels 11FL.
Hydraulic pressure cylinders 18FL to 18RR as fluid pressure cylinders respectively interposed between the wheel side members 14 to 11RR and pressure control valves for adjusting the operating pressures of the hydraulic cylinders 18FL to 18RR.
20FL to 20RR, the hydraulic source 22 of this hydraulic system, and the hydraulic source 22
And a pressure accumulator 24, 24 interposed between the pressure control valves 20FL to 20RR, and a lateral acceleration sensor 26, a longitudinal acceleration sensor 27, and a vertical acceleration sensor 28FL for detecting acceleration generated in each direction of the vehicle body. ˜28RR and a controller 30 that individually controls the output pressure of the pressure control valves 20FL to 20RR based on the detection signals of the sensors. Further, each of pressure chambers L to be described later of the hydraulic cylinders 18FL to 18RR is connected to a vibration absorbing accumulator 34 via a throttle valve 32. Further, a coil spring 36 having a relatively low spring constant and supporting the static load of the vehicle body is disposed between the upper and lower portions of the hydraulic cylinders 18FL to 18RR.

Each of the hydraulic cylinders 18FL to 18RR has a cylinder tube 18
The cylinder tube 18a has a piston 18c
A lower pressure chamber L separated by is formed. The lower end of the cylinder tube 18a is attached to the wheel side member 14, and the upper end of the piston rod 18b is attached to the vehicle body side member 10.
Attached to. Further, each of the pressure chambers L is connected to the output ports of the pressure control valves 20FL to 20RR via the hydraulic pipe 38.

Further, each of the pressure control valves 20FL to 20RR has a conventionally known three-port proportional electromagnetic pressure reducing valve having a cylindrical valve housing and a proportional solenoid integrally provided therein (for example, JP-A-64-74111). No.)). And
By adjusting the command value S consisting of the current value supplied to the exciting coil of the proportional solenoid, the movement distance of the poppet housed in the valve housing, that is, the spool position is controlled, and the hydraulic power source 22 supplies the supply port and the output port. The hydraulic oil supplied to the hydraulic cylinders 18FL to 18RR via the hydraulic cylinders 18FL to 18RR and the hydraulic oil returning from the hydraulic cylinders 18FL to 18RR to the hydraulic pressure source 22 via the output port and the return port can be controlled.

Here, the command value S (: S _FL ~ S applied to the exciting coil
_RR ) and the control pressure P output from the output port of the pressure control valve 20FL (to 20RR) are as shown in FIG. That is, when the minimum command value S _MIN considering noise is the minimum control pressure P _NIM , increasing the command value S from this state causes the control pressure P to increase linearly in proportion to the command value S, and the maximum command value P _NIM . When the value is S _MAX , it becomes the maximum control pressure P _MAX corresponding to the set line pressure.

On the other hand, a lateral acceleration sensor 26 and a longitudinal acceleration sensor 27 are provided at a predetermined position in front of the center of gravity of the vehicle,
These sensors 26, 27 detect lateral acceleration in the lateral (vehicle width) direction acting on the vehicle body and longitudinal acceleration in the front-rear direction, and use a value corresponding to the acceleration and a positive / negative analog voltage value corresponding to the acting direction. The lateral acceleration signal g _Y and the longitudinal acceleration signal g _X are output to the controller 30, respectively. Further, the vertical acceleration sensors 28FL to 28RR are respectively provided at the vehicle body positions substantially directly above the front left to rear right wheels 11FL to 11RR,
These sensors 28FL to 28RR detect the vertical acceleration of the vehicle body generated at each wheel position, and have a positive / negative analog voltage value having a value corresponding to the vertical acceleration and a direction in which the vertical acceleration is generated. the vertical acceleration signal g _ZFL to g _ZRR in which each output to the controller 30.

Further, as shown in FIG. 4, the controller 30 further includes A / D converters 70A and 70B for converting the input analog amounts of the lateral acceleration detection signal g _Y and the longitudinal acceleration detection signal g _X into digital amounts,
Also the A / D converter 71A~71D for converting the analog quantity of vertical acceleration signal g _ZFL to g _ZRR into digital amount, and a microcomputer 72 for processing, the microcomputer 72
D / A converters 73A to 73D that individually convert the digital quantity control signal SC output from the analog quantity, and command values S _{FL to} S _FR corresponding to the analog quantity control signal SC to the pressure control valve.
It has drive circuits 74A to 74D for individually outputting to 20FL to 20RR.

Among them, the microcomputer 72 is configured to include at least an interface circuit 76, an arithmetic processing unit 78, and a storage device 80 including a RAM and a ROM, and the interface circuit 76 is configured to include an I / O port and the like. The arithmetic processing unit 78, the detection signal g _Y through the interface circuit 76 sequentially reads the g _X, and g _ZFL to g _ZRR, performs arithmetic and other processing described later based on these. The storage device 80 previously stores a predetermined program, fixed data, and the like necessary for executing the processing of the arithmetic processing device 78, and can store the processing result of the arithmetic processing device 78.

 Next, the operation of the above embodiment will be described.

When the vehicle ignition switch is turned on,
The controller 30 is activated to execute the timer interrupt processing shown in FIG. 5 at predetermined time intervals (for example, 20 msec) during execution of the predetermined main program.

The processing of FIG. 5 will be described. First, in the step shown in FIG.
The acceleration detection signals g _Y , g _X , g _{ZFL to} g _ZRR are sequentially read, and the process _proceeds to step. In this step, the lateral acceleration G _Y , the longitudinal acceleration G _X , and the vertical acceleration G _{ZFL to} G _ZRR are calculated from the detection signals read in the step, and the calculated values are temporarily stored in a predetermined storage area, and then the _{process proceeds} to the step. To do.

In step, vertical acceleration G calculated in step
_ZFL ~G _ZRR to the vertical velocity of the vehicle body is subjected to integral calculation V _ZFL ~V
_{Calculate ZRR} .

Then the process proceeds to step, of the calculated value of vertical velocity V _ZFL ~V _ZRR in step, the vehicle front side of the right and left vertical velocity V _ZFL, using V _ZFR, the absolute value of the roll angular velocity, |
_Obtained from the calculation of | = | G _ZFR −G _ZFL |.

Next, the process proceeds to step, and the correction gain K _G as the roll motion suppression gain according to the roll angular velocity || is set by referring to the storage table stored in the storage device 80 in advance and corresponding to FIG. According to this storage table, when the roll angular velocity || = 0, the correction gain K _G =
A 0, also changes the gain K _G in proportion to ||.

Then proceeds to step, with respect to the vertical direction control gain K _Z which is set to a fixed value in advance, performs a calculation of _{K Z = K 2 + K G} , by adding the correction gain K _G in the vertical direction control gain K _Z Correction is performed according to the roll angular velocity.

After the vertical control gain K _Z is corrected in order to damp the roll motion in this way, the processes from step to are performed, and the normal command values for damping the vehicle in the vertical, front-rear, and lateral directions are performed. Is calculated.

First, in the step, in order to obtain the command values S _{ZFL to} S _ZRR for the bounce control and roll control, S _ZFL = V _ZFL is used by using the vertical control gain set in the above step.
-K ₂ , S _ZFR = V _ZFR -K _Z , S _ZRL = V _ZRL -K _Z , S _ZRR = V _ZRR-
KZ is calculated for each wheel.

Then, in step, anti-pitch (anti-dive, anti-squat) for acceleration and deceleration traveling S _X a command value for the control is obtained by performing the calculation of _{S X = G X · K X} . Here, the longitudinal acceleration G _X is a calculated value in steps, and the longitudinal control gain K _X is a value preset to a predetermined value.

Then, the process proceeds to step, and the command value S _Y for anti-roll control is calculated by S _Y = G _Y · K _Y. Where G _Y
Is a value calculated in steps, and K _Y is a preset lateral control gain.

Then, move to step, and total value of each command value S _FL ~ S
_RR is S _FL = S _ZFL ＋ S _X ＋ S _Y ＋ S _N , S _FR ＝ S _ZFR ＋ S _X ＋ S _Y ＋
S _N , S _RL = S _ZRL + S _X + S _Y + S _N , S _RR = S _ZRR + S _X + S _Y + S _N Calculate for each wheel (However, command values S _X , S _Y Therefore, the vehicle body sinking side is added as a positive value), and the process proceeds to step. Here, S _N is a command value for maintaining the vehicle height, but is not necessarily limited to the neutral command value S _N.

In this step, the command value S calculated in step
_The control signal SC corresponding to _{FL to} S _RR is output individually. Each of the control signals SC is converted into an analog amount by the D / A converters 73A to 73D, and the pressure control valve 20FL to the drive circuits 74A to 74D.
Output as command values S _{FL to} S _{RR to the 20 RR} excitation coil. This causes the control pressure P of the pressure control valve to change to the command value S _FL.
~ Individually controlled according to S _RR .

 Next, the overall operation will be described.

Now, it is assumed that the vehicle is traveling straight on a good road with no unevenness at a constant speed. In this state, rolls, dives, scuts, bounces, etc. do not occur, so the lateral acceleration sensor 26, longitudinal acceleration sensor 27, vertical acceleration sensor 28FL
The detection signals g _Y , g _X , g _{ZFL to} g _{ZRR of} ~ _28RR are all zero, and the lateral acceleration G _Y , longitudinal acceleration G _X , and vertical acceleration G _{ZFL to} G _ZRR are also all zero (step in FIG. 5, ). Therefore, the vertical speed
V _{ZFL to} V _ZRR = 0, roll angular velocity = 0, and correction gain K _G =
Since it is 0, the command values S _{FL to} S _RR = neutral value S _N calculated in the process of FIG. 5 described above are obtained, and the pressure control valves 20FL to 20RR are in neutral pressure in the pressure chamber L of the hydraulic cylinders 18FL to 18RR. Output P _N (see Fig. 3). As a result, the hydraulic cylinder 18FL ~
The 18RR generates a force according to the neutral pressure P _N , and the vehicle body is held in a flat posture with a predetermined vehicle height value.

In this straight traveling state, the wheels 11FL to 11RR pass through a road surface uneven portion, that is, an irregular road, so that a vibration input of a relatively low frequency corresponding to the sprung resonance frequency range is input to the pressure chamber L via the wheel side member 14. It is assumed that the input has been made. In this case, the pressure change of the hydraulic cylinders 18FL to 18RR due to the input vibration is absorbed between the hydraulic cylinder 22 and the hydraulic power source 22 via the pressure control valves 20FL to 20RR, whereby the vertical vibration can be suppressed to some extent.

However, if the vertical vibration cannot be completely absorbed even by the damping control of the pressure control valves 20FL to 20RR, the vehicle body is vibrated vertically and bounces, or if the left and right wheel position irregularities are different from each other, the vertical vibration is applied. Rolling occurs in the vehicle due to the difference in vibration force, and vertical acceleration signals g _{ZFL to} g _ZRR corresponding to this bounce and rolling are _detected by the vertical acceleration sensor 28FL.
〜28RR are detected respectively.

In such a state, the controller 30, the vertical acceleration signal g _ZFL to g a vertical acceleration G _ZFL ~G _ZRR respectively calculated from _ZRR, the vertical acceleration G _ZFL ~G _ZRR based on the vehicle body vertical velocity V
_{ZFL to} V _ZRR are _{calculated respectively} . In addition, roll angular velocity ||
The determined, to set the correction gain K _G in proportion to the || sequentially correction after gain K and _G content only corrects the vertical control gain K _Z, generating a damping force proportional to the vertical velocity V _ZFL ~V _{ZRR Determine the} command value S _{ZFL to} S _ZRR to be performed (step in Fig. 5)
). That is, the command values S _{ZFL to} S _ZRR are the sum of the command value components that attenuate the roll due to bounce and road surface irregularity.

And the command value to attenuate bounce and rolling
S _{ZFL to} S _ZRR are added to the command value S _N , and the added value S _{FL to} S _RR
The control signal SC is output corresponding to
). Therefore, the hydraulic cylinders 18FL to 18RR are set to the command value S _ZFL.
The operating force generated corresponding to ~ S _ZRR becomes a damping force having a predetermined phase difference with respect to the vertical displacement of the vehicle body, and properly damps the bounce and rolling of the vehicle body. Therefore,
Even when the vehicle is traveling straight on an irregular road and lateral acceleration does not occur, a substantially flat vehicle attitude can be maintained by both the bounce and rolling controls. At this time, rolling may not occur depending on the concavo-convex state, and || = 0 at that time, so only the bounce control described above is performed.

In this way, the active suspension 12 of this embodiment is
Unlike the case of the conventional example described above, even when rolling occurs in a state where lateral acceleration G _Y is not generated (for example, a state where the vehicle is not turning) because the vehicle body is vibrated up and down due to road surface irregularity during constant-speed straight traveling. However, there is an advantage that the rolling is properly suppressed. Moreover, in this embodiment, the roll angular velocity |
Since the value of the correction gain K _G is changed in proportion to the magnitude of |, the damping force corresponding to the roll angular velocity can be obtained, and the correction gain K _G is constantly increased in order to obtain a large damping force. Compared with the case, there is also an advantage that the riding comfort does not deteriorate in a region where the roll angular velocity is relatively small.

In addition, the vibration input of relatively high frequency corresponding to the unsprung resonance frequency range due to the fine unevenness of the road surface is the hydraulic cylinder 18FL.
When transmitted to the pressure chamber L of 18 RR, the pressure fluctuation due to this vibration input is absorbed by the fixed throttle 32 and the accumulator 34, and the deterioration of riding comfort is prevented.

Furthermore, this time, if you accelerate or decelerate while driving straight on a good road,
As a result, longitudinal acceleration is generated, and the vehicle body tries to make pitch movements such as nose dive and scut with a pitch angle according to the inertial force. At this time, the generated longitudinal acceleration is detected by the longitudinal acceleration sensor 27, and the detection signal g _X is supplied to the controller 30. Therefore, the controller 30
Calculates the longitudinal acceleration G _X corresponding to the acceleration / deceleration state, calculates the command value S _X proportional to the absolute value of this acceleration G _X , and calculates the command values S _{FL to} S that resist the pitch motion for each wheel. Perform control command by _RR (Fig. 5, step ,,,
).

That is, the hydraulic cylinders 18FL, 18FR on the side of the vehicle body sinking
(Or 18RL, 18RR), its command value S _FL , S _FR (or S _RL ,
S _RR ) increases the working pressure, and in the hydraulic cylinders 18RL, 18RR (or 18FL, 18RR) on the body lifting side, the command values S _RL , S _RR (or S _FL , S _FR ) decrease The working pressure decreases. For this reason, a force against the depression is generated on the vehicle body sinking side, and the vehicle body rising side does not promote the lifting, so an anti-pitch moment is generated in advance on the vehicle body and the vehicle body front portion A nose dive that sinks in and a scut that sinks in the rear part of the vehicle body are reliably suppressed, and stability and steering stability in a high vehicle attitude are secured.

Furthermore, when the vehicle is steered from the constant-speed straight-running state on a good road to a turning state, lateral (vehicle width) acceleration corresponding to the turning state is generated in the vehicle body, and the inertial force causes the outer wheel side of the vehicle body to move. A sinking roll is about to occur. At this time, in the controller 30, the lateral acceleration G _Y is calculated from the lateral acceleration detection signal g _Y of the lateral acceleration sensor 26, and the total command value S including the command value S _Y corresponding to the anti-roll moment is calculated.
_{FL to} S _RR are calculated, and pressure control is performed based on the command values S _{FL to} S _RR (steps in FIG. 5, ...). As a result, as in the case of pitch control, the operating pressure of the outer wheel side hydraulic cylinders 18FL, 18RL (or 18FR, 18RR) is increased,
On the contrary, the working pressure of the hydraulic cylinders 18FR, 18RR (18FL, 18RL) on the inner ring side is lowered, and the anti-roll moment against the roll is generated in advance on the vehicle body, causing the vehicle body to sink on the outer wheel side and the vehicle body on the inner wheel side. Lifting is prevented and a substantially flat body posture is maintained.

In the case of traveling in which two or more vehicle motions occur simultaneously among bounce, pitch, and roll, command values for suppressing each posture change are individually calculated, and the same suppression control as that described above is performed at the same time.

As described above, in the first embodiment, the vertical acceleration sensors 28FL, 28FR,
The processes of the A / D converters 71A and 71B and the step of FIG. 5 constitute the vertical acceleration detecting means, the processing of the step of the figure corresponds to the vertical velocity calculating means, and the processing of the step of the figure becomes the roll angular velocity calculating means. Correspondingly, the processing of the step in the figure corresponds to the gain setting means, and the step of the figure in the figure ...
Processing, D / A converters 73A to 73D, and drive circuits 74A to 74D constitute command value calculation means.

(Second Embodiment) Next, a second embodiment of the present invention will be described with reference to FIGS. 7 and 8. Here, the same symbols are used for the same components as in the first embodiment.

In the second embodiment, the correction gain K _G in the first embodiment described above is changed according to the value of the vehicle speed V. As shown in FIG. 7, a vehicle speed sensor 82 is newly added. The detection signal v of the vehicle speed sensor 82 is input to the controller 30. The vehicle speed sensor 82 has a structure for magnetically or optically detecting the rotational speed of the output shaft of the transmission, and outputs a vehicle speed signal v composed of a pulse signal corresponding to the engine rotational speed.

On the other hand, the controller 30 performs the same processing as that in FIG. 5 described above, but in the step corresponding to the step in FIG. 5, processing for reading the vehicle speed detection signal v is added, and in the step corresponding to the step, , A process for obtaining the vehicle speed V is added, and in a step corresponding to the step, the roll angular velocity || and the correction gain K _G according to the vehicle speed V are set by referring to the storage table corresponding to FIG. That is, the vehicle speed V is used as a parameter, and as the vehicle speed V increases, the change rate of the correction gain K _G with respect to the change of the roll angular velocity || is increased. This data is stored in advance in the storage device 80 in the form of a table. There is.

 The other structure is the same as that of the first embodiment.

Therefore, according to the second embodiment, in addition to the same effect as that of the first embodiment, the roll control by the irregular road surface during straight traveling is finely controlled according to the vehicle speed V, and more reliable posture control is achieved. There are advantages. That is, even when the vehicle travels straight on the same irregular road, normally, as the vehicle speed V increases,
Since roll momentum due to the vertical vibration is large, the vehicle speed V is corrected by the proportional gain K _G, i.e. by making the vertical direction control gain K _Z is a finely changes, to fine-tune the damping force relative to the road surface irregularities, the advantage described above can get.

(Modification) Next, a modification will be described with reference to FIGS. 9 and 10. Here, the same symbols are used for the same components as in the first embodiment.

In this modification, the correction gain K _G , that is, the vertical control gain K _Z in the first embodiment described above is changed according to the roll angular acceleration. For this,
The microcomputer 72 of the controller 30 is adapted to execute the processing shown in FIG. 9 as a timer interrupt, and other configurations are the same as in the first embodiment.

The processing of FIG. 9 will be described. First, in the step of FIG.
Is the acceleration detection signal g _Y, g _X, sequentially reads g _ZFL to g _ZRR, the process proceeds to step. In this step, the lateral acceleration G _Y , the longitudinal acceleration G _X , and the vertical accelerations G _{ZFL to} G _ZRR are calculated from the detection signals read in the step, and these calculated values are temporarily stored, and then the _{process proceeds} to step.

Vertical acceleration in step G _ZFL
~ _{Left /} right vertical acceleration on the front side of the vehicle among the calculated values of G _ZRR
Use G _ZFL and G _ZFR to calculate the absolute value of roll angular acceleration |
_Obtained from the calculation of | = | G _ZFR −G _ZFL |. Next, the process proceeds to step, and the roll angular acceleration | stored in the storage device 80 in advance is referred to by referring to the storage table corresponding to FIG.
Correction gain K _G as roll motion suppression gain according to |
Set. According to this storage table, when the roll angular acceleration || = 0, the correction gain K _G = 0 and |
The gain K _G also changes in proportion to |.

Next, in step S, the command values S _{GFL to} S _GRR for suppressing the rolling motion of the vehicle based on the road surface irregularity are set to S _GFL
＝ G _ZFL・ K _G , S _GFR ＝ G _ZFR・ K _G , S _GRL ＝ G _ZRL・ K _G , S _GRR ＝ G
Husband by the operation of _ZRR · K _G people seek. Where G _ZFL ~ G _ZRR
Is a calculated value in the step, and K _G is a value set in the step.

In this way, the command values S _GFL ~ S that suppress the roll motion
_{After obtaining the GRR} , the processes from step to are performed to calculate a normal command value for damping the vehicle vertically, longitudinally and laterally.

First, in step, the vertical acceleration V _{ZFL of the} vehicle body is calculated by _performing integral calculation on the vertical accelerations G _{ZFL to} G _ZRR calculated in step.
~ _Calculate V _ZRR . In the step, in order to obtain the command values S _{ZFL to} S _ZRR for the bounce control, S _ZFL = V _ZFL · K _Z , S _ZFR using the preset vertical control gain K _Z.
= V _ZFR · K _Z , S _ZRL = V _ZRL · K _Z , S _ZRR = V _ZRR · K _Z is calculated for each wheel.

Next, in step, a command value S _X for anti-pitch (anti-dive, anti-scut) control for acceleration / deceleration running is calculated by calculating S _X = G _X · K _X.
Here, the longitudinal acceleration G _X is the calculated value at the step,
The front-rear direction control gain K _X is a value preset to a predetermined value.

Then, the process proceeds to step, and the command value S _Y for anti-roll control is calculated by S _Y = G _Y · K _Y. Where G _Y
Is a value calculated in steps, and K _Y is a preset lateral control gain.

Then, move to step, and total value of each command value S _FL ~ S
_RR is S _FL = S _ZFL + S _X + S _Y + S _GFL + S _N , S _FR = S _ZFR + S _X +
S _X + S _Y + S _GFR + S _N , S _RL = S _ZRL + S _X + S _Y + S _GRL + S _N , S _RR
= S _ZRR + S _X + S _Y + S _GRR + S _N is calculated for each wheel (however, the command values S _X and S _Y are in opposite phase on the front and rear, left and right, and the vehicle sinking side is added as a positive value) , Move to step. Here, S _N is a command value for maintaining the vehicle height, but is not necessarily limited to the neutral command value S _N.

In this step, the control signals SC corresponding to the calculated values S _{FL to} S _RR of the steps are individually output. This control signal
The SCs are converted into analog amounts by the D / A converters 73A to 73D, and output from the drive circuits 74A to 74D as command values S _{FL to} S _RR to the exciting coils of the pressure control valves 20FL to 20RR. As a result, the control pressure P of the pressure control valve is individually controlled according to the command values S _{FL to} S _RR .

 Next, the overall operation will be described.

Now, it is assumed that the vehicle is traveling straight on a good road with no unevenness at a constant speed. In this state, rocking such as roll, dive, scut, and bounce does not occur, so that the hydraulic cylinders 18FL to 18RR generate a force corresponding to the neutral pressure P _N as in the first embodiment, so that the vehicle body has a predetermined vehicle body. Holds a high, flat posture.

In this straight traveling state, it is assumed that the wheels 11FL to 11RR pass through a road surface uneven portion, that is, an irregular road. This allows the pressure control valve
If the vertical vibration cannot be completely absorbed even with the damping control of 20FL to 20RR, the vehicle body is vibrated vertically to bounce, or if the irregular positions of the left and right wheels are different from each other, it is due to the difference in the vertical excitation force. rolling the vehicle caused by the vertical acceleration signal corresponding to the bounce and rolling g _ZFL to g _ZRR
Are respectively detected by the vertical acceleration sensors 28FL to 28RR.

In such a state, the controller 30, the vertical acceleration signal g _ZFL to g a vertical acceleration G _ZFL ~G _ZRR respectively calculated from _ZRR, the vertical acceleration G _ZFL ~G _ZRR based on the vehicle body vertical velocity V
_{ZFL to} V _ZRR are _{calculated respectively,} and command values S _{ZFL to} Z _ZRR that generate a damping force proportional to the vertical speeds V _{ZFL to} V _ZRR are _calculated (steps in FIG. 9 ,,). At the same time, the controller 30 controls the front vertical acceleration G _ZFL , G representing the left and right of the vehicle.
The absolute value of the roll angular acceleration due to the difference in _ZFR is obtained, the correction gain K _G corresponding to this value || is set, and the command values S _{GFL to} S _GRR for suppressing the roll motion are obtained for each wheel ( Same step ~).

Then, the command values S _{ZFL to} S _ZRR and S _{GFL to} S _GRR for damping and suppressing bounce and rolling are added together with the command value S _N , and the control signal SC is output corresponding to the added value S _{FL to} S _RR. (Step in the figure). Therefore, the operating force generated by the hydraulic cylinders 18FL to _18RR corresponding to the command values S _{ZFL to} S _ZRR becomes a damping force having a predetermined phase difference with respect to the vertical displacement of the vehicle body, and accurately damps the bounce of the vehicle body. Let At the same time, the hydraulic cylinders 18FL to 18RR set the command values S _{GFL to} S
_The operating force generated in response to _GRR is a decrease in the operating pressure, that is, a weakening of the operating pressure on the rising side of the vehicle body, and an increase of the operating pressure, that is, an operating force on the sinking side of the vehicle body. After all, it will strengthen and resist the subsidence, so in the end
Demonstrate the moment that suppresses rolling. Therefore, even when the vehicle is traveling straight on an irregular road and longitudinal acceleration is not generated, a substantially flat vehicle posture can be maintained by both the bounce control and the rolling control.

 Other operational effects are the same as those of the first embodiment.

In the above modification, the vertical acceleration sensors 28FL, 28FR, A / D converters 71B, 71D and the process of FIG. 9 constitute the vertical acceleration detecting means, and the process of the same figure corresponds to the roll angular acceleration calculating means. However, the processing of the step in the figure corresponds to the gain setting means, the processing of the step in the figure, the D / A converters 73A to 73D, and the drive circuits 74A to 74D constitute the command value computing means.

By the way, in the above modification, the vehicle speed V is detected in the same manner as in the second embodiment described above, and the correction gain K _G
May be changed in accordance with not only the roll angular acceleration but also the change in vehicle speed V. Further, the roll momentum calculation means of the modified example is not limited to the one that calculates the roll angular acceleration, and may be a structure that obtains the roll angle from the vertical acceleration, for example.

It should be noted that the vertical acceleration detecting means of the present invention is not limited to the one that obtains the vertical acceleration based on the vertical acceleration sensors on the front right side and the front left side of the vehicle as described in the above embodiments,
For example, the detection signal of the vertical acceleration sensor on the rear side of the vehicle may be used, or the right and left average values obtained by averaging the detection signals of the front and rear vertical acceleration sensors on the left and right sides of the vehicle may be used.

Further, the fluid pressure cylinder of the present invention is not limited to the case where the hydraulic cylinder is applied as in each of the above-mentioned embodiments, and may be a configuration using an air pressure cylinder or the like.

Moreover, the is constituted by a microcomputer in the controller in the embodiments, this is for example, an integrator for integrating the vertical acceleration detection signal g _ZFL to g _ZRR, vertical velocity signal V _ZFR, the difference between V _ZRR operation Differentiator, an absolute value circuit that calculates the absolute value of the difference, a function generator that generates a correction gain signal K _G according to the difference signal ||, and a correction gain signal K _G and a fixed gain signal K _Z are added. It may be configured by an analog electronic circuit including an adder, a variable gain amplifier that changes the gain in proportion to the corrected control gain signal K _Z ′, and amplifies each vertical acceleration signal g _{FL to} g _RR .

〔The invention's effect〕

As described above, according to the first aspect of the invention, the roll angular velocity of the vehicle body is calculated based on the vertical velocity obtained by integrating the vertical acceleration detected on the left wheel side and the right wheel side of the vehicle body by the vertical velocity calculating means, and the roll angular velocity is calculated as the roll angular velocity. A roll motion suppression gain is set based on the roll motion suppression gain, and a command value for suppressing the roll motion is calculated by the command value calculation unit based on the set roll motion suppression gain and the vertical speed calculated by the vertical speed calculation unit. The working pressure of the fluid pressure cylinder is controlled. For this reason, even when lateral acceleration such as when traveling straight at a constant speed does not occur, even when the left and right wheels of the vehicle body are vertically vibrated with different forces to cause rolling on the vehicle body by passing through the irregular road surface, On the other hand, since the roll motion suppression gain is set according to the generated roll, rolling can be properly suppressed, and the effect of stabilizing the vehicle attitude and improving the steering stability can be obtained. Moreover, since the value of the roll motion suppression gain is set in proportion to the roll angular velocity, it is possible to obtain a damping force corresponding to the roll angular velocity, and thus the roll motion suppression gain is constantly increased in order to obtain a large damping force in advance. As compared with the case where the roll angular velocity is kept, there is an effect that it is possible to prevent deterioration of riding comfort in a region where the roll angular velocity is relatively small.

Also, in the invention of claim 2, the roll angle or the roll angular acceleration is calculated based on the vertical acceleration detection value of the vertical acceleration detecting means, and the roll motion suppression gain increases as the roll angle or the roll angular acceleration increases. Is set, a command value for suppressing the roll motion is calculated based on the roll motion suppression gain and the detection value of the vertical acceleration detecting means, and the command value is given to each pressure control valve. Similar to the invention, it is possible to obtain an effect that rolling that is likely to occur due to road surface irregularity or the like is accurately suppressed and that deterioration of riding comfort in a region where the roll angle or the roll angular acceleration is small is prevented.

[Brief description of drawings]

FIG. 1 is a diagram corresponding to a claim of the present invention, FIG. 2 is a schematic configuration diagram showing a first embodiment of the present invention, and FIG. 3 is a graph showing a relationship between a command value for a pressure control valve and an output control pressure. FIG. 4 is a block diagram showing an example of a controller, FIG. 5 is a schematic flowchart showing an example of a processing procedure executed in the controller, and FIG. 6 shows a relationship between the roll angular velocity and the correction gain in the first embodiment. FIG. 7 is a partial block diagram showing the configuration of the second embodiment of the present invention, FIG.
FIG. 9 is a graph showing the relationship between the roll angular velocity with the vehicle speed as a parameter and the correction gain in the second embodiment, FIG. 9 is a schematic flowchart showing an example of the processing procedure executed in the modification, and FIG. 6 is a graph showing the relationship between roll angular acceleration and correction gain. In the figure, 10 is a vehicle body side member, 12 is an active suspension, and 14
Is a member on the wheel side, 18FL to 18RR are front left to rear right hydraulic cylinders,
20FL to 20RR are front left to rear right pressure control valves, 28FL to 28RR are vertical acceleration sensors, 30 is a controller, 71A to 71D are A / D converters, 73A to 73D are D / A converters, and 74A to 74D are driving. Circuit.

Front page continuation (72) Inventor Nao Yonezawa 2 Takaracho, Kanagawa-ku, Yokohama, Kanagawa Nissan Motor Co., Ltd. (56) Reference JP 59-140112 (JP, A) JP 63-242707 (JP, A)

Claims (2)

[Claims] 1. A fluid pressure cylinder interposed between a vehicle body side member and a wheel side member for each wheel, and a pressure control valve for individually controlling the operating pressure of each fluid pressure cylinder according to a command value. And vertical acceleration detecting means for detecting the vertical acceleration of the vehicle body on the right wheel side and the left wheel side, vertical speed calculating means for calculating the vertical speed by integrating the detection values of the vertical acceleration detecting means, and the vertical speed calculating means. Roll angular velocity calculation means for calculating the roll angular velocity of the vehicle body based on each calculated value of the speed calculation means, and gain setting means for setting a roll motion suppression gain that increases in accordance with an increase in the calculated value of the roll angular velocity calculation means, And a command value calculation unit for calculating the command value for suppressing the roll motion for each of the left and right wheels based on the roll motion suppression gain set by the gain setting unit and the calculation value of the vertical speed calculation unit. Active suspension according to claim. 2. A fluid pressure cylinder interposed between a vehicle body side member and a wheel side member for each wheel, and a pressure control valve for individually controlling the operating pressure of each fluid pressure cylinder according to a command value. And a vertical acceleration detecting means for detecting the vertical acceleration of the vehicle body on the right wheel side and the left wheel side, and a roll angle or angular acceleration for calculating the roll angle or angular acceleration of the vehicle body based on the respective detected values of the vertical acceleration detecting means. Calculating means, gain setting means for setting a roll motion suppressing gain that increases in accordance with an increase in the calculated value of the roll angle or angular acceleration calculating means, roll motion suppressing gain set by the gain setting means, and the vertical acceleration detection. An active suspension comprising: command value calculation means for calculating the command value for suppressing the roll motion for each of the right and left wheels based on the detected value of the means.