JP2503254B2 - Active suspension - Google Patents

Description

TECHNICAL FIELD The present invention relates to an active suspension, and more particularly, to an active suspension.
The present invention relates to an active suspension that detects lateral acceleration generated in the lateral direction of a vehicle and controls roll of a vehicle body based on the detected value.

[Conventional technology]

Conventionally, as this type of active suspension, for example, the one described in JP-A-62-295714 proposed by the present applicant is known.

This suspension includes a fluid pressure cylinder mounted between the vehicle body side member and each wheel side member, a pressure control valve for individually controlling the operating pressure of each of the fluid pressure cylinders according to a command value, and a vehicle body It has an acceleration detecting means whose main part is a sensor for detecting lateral acceleration or longitudinal acceleration, and control means for calculating a command value based on the detection result of this acceleration detecting means and outputting it to each pressure control valve. As a result, the posture change of the vehicle body in the left-right direction or the front-rear direction is suppressed.

[Problems to be Solved by the Invention]

In such a conventional active suspension,
Usually, a lateral acceleration sensor is arranged at the center of gravity of the vehicle to detect the lateral acceleration at the center of gravity. However, the suspension control system has a phase delay due to the response delay of the control valve, the command value calculation time, etc. Therefore, as described above, simply detecting the lateral acceleration at the center of gravity suppresses the roll. Was not enough and the posture control effect was not as expected.

Therefore, in order to overcome this situation, a lateral acceleration sensor may be provided at a position in front of the center of gravity of the vehicle. However, the detection position in front of the center of gravity, which is suitable for compensating for the control delay of the suspension system, is
Usually, it is the mounting position of the transmission and its operating device, and it is difficult to mount the lateral acceleration sensor. Moreover, the mounting height of the lateral acceleration sensor has no meaning unless the position is close to the roll axis of the vehicle so as not to be affected by the roll motion of the vehicle. There was an unsolved problem of becoming.

On the other hand, since the position of the center of gravity of the vehicle changes depending on the loading state depending on the number of passengers and the load, even if the lateral acceleration sensor is installed in the standard loading state, the detected value varies depending on the loading state change. There is also an unsolved problem that the occupant feels uncomfortable because the roll suppressing characteristics are different.

The present invention has been made in view of such an unsolved problem, and accurately obtains the lateral acceleration at a desired position in front of the center of gravity of the vehicle without being affected by the restrictions on sensor mounting. The first problem to be solved is to perform accurate roll control by compensating the phase delay of the control system by using the lateral acceleration.

Further, the present invention is intended to solve the problem that it is possible to maintain the roll control with high accuracy according to the above-mentioned problems, and to make the roll restraining characteristic a stable characteristic without changing depending on the loaded state. This is the second issue.

[Means for solving the problem]

In order to solve the first problem described above, the apparatus according to claim 1 of the present invention, as shown in FIG. 1 (a), changes the actuator inserted between the vehicle body and the wheels and the operating state of the actuator. An active suspension having actuator control means for controlling according to a possible command value, and changing and controlling the command value according to a lateral posture change of the vehicle body. The first and second lateral acceleration sensors for respectively detecting the acceleration acting in the lateral direction of the vehicle body at the installed position, and the center of gravity of the vehicle based on the detection values of the first and second lateral acceleration sensors A lateral acceleration calculating means for calculating a lateral acceleration at a desired front calculation position; and a command value calculating means for calculating a command value according to a calculated value of the lateral acceleration calculating means and giving the command value to the actuator control means. Equipped ing.

Further, in order to solve the second problem, the device according to claim 2 of the present invention is, as shown in FIG. 1 (b), an actuator inserted between the vehicle body and the wheel, and an operating state of the actuator. And an actuator control unit that controls the command value according to a changeable command value, and the active suspension in which the command value is controlled to be changed according to a lateral posture change of the vehicle body is separated in the front and rear of the vehicle. The first and second lateral acceleration sensors that are arranged and detect the lateral accelerations of the vehicle body at the arranged positions respectively, and the vehicle of the vehicle based on the detection values of the first and second lateral acceleration sensors. Lateral acceleration calculation means for calculating lateral acceleration at a changeable calculation position in front of the center of gravity, and command value calculation for calculating a command value according to the calculated value of the lateral acceleration calculation means and giving the command value to the actuator control means. means And a vehicle state detecting means for detecting a vehicle state, and a lateral acceleration calculation position changing means for changing a calculation position by the lateral acceleration calculating means according to the vehicle state information by the vehicle state detecting means. ing.

[Action]

In the device according to the first aspect of the present invention, the first and second lateral acceleration sensors detect the lateral acceleration at the predetermined front and rear positions of the vehicle. The lateral acceleration calculation means calculates the lateral acceleration at the calculated position in front of the center of gravity based on the two lateral acceleration detection values, and the command value calculation means calculates a command value according to the lateral acceleration calculation value and calculates the command value. It is given to the actuator control means.
The actuator control means controls the actuator between the wheels and the vehicle body in accordance with the given command value, whereby roll restraint control is performed.

That is, the value calculated by the lateral acceleration calculating means is a value obtained by adding the product value of the yaw angular acceleration and the distance from the center of gravity point to the calculated position to the lateral acceleration at the vehicle center of gravity position at that time. Therefore, if the lateral acceleration calculated value of the present invention is used, the phase delay of the control system can be compensated by such a product value, and more accurate anti-roll control can be obtained.

Further, in the apparatus according to the second aspect, the roll control is performed by the above action, the loading state of the vehicle is detected by the loading state detection means, and the lateral acceleration calculation position is the lateral acceleration calculation according to the detection information. The position is appropriately changed by the position changing means. As a result, if the number of passengers changes and the loading state changes, the lateral acceleration calculation position is adjusted accordingly.
The roll restraining property can be kept almost constant.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 2 to 14. This embodiment corresponds to the active suspension according to the second aspect of the present invention.

First, in FIG. 2, 10FL to 10RR are front left to rear right wheels, 12 is a wheel side member, 14 is a vehicle body side member, and 16 is an active suspension.

The active suspension 16 includes hydraulic cylinders 18FL to 18RR as actuators provided separately between the vehicle body side member 14 and each wheel side member 12, and the hydraulic cylinders 18FL to 18RR.
Pressure control valves 20FL to 20RR as actuator control means for adjusting each cylinder pressure (operating state) of 18RR, hydraulic pressure source 22 of this hydraulic system, hydraulic pressure source 22 and pressure control valve 20FL to
Accumulators 24, 24 for pressure accumulation inserted between RR, first and second lateral acceleration sensors 26a, 26b for detecting lateral acceleration acting in the lateral direction of the vehicle body, and relative displacement between wheels and vehicle body Height sensors 28FL to 28RR for detection and pressure control valves 20FL to 20RR
And a controller 30 for individually controlling the output pressure of the. Further, the active suspension 16 includes coil springs 36FL to 36RR which are individually installed in parallel between the wheel side member 12 and the vehicle body side member 14 with respect to the hydraulic cylinders 18FL to 18RR.
, 32, and accumulators 34, ..., 34 for absorbing vibration, which individually communicate with pressure chambers L of hydraulic cylinders 18FL to 18RR, which will be described later. Where each coil spring 36
Has a relatively low spring constant and supports the static load of the vehicle body.

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

Each of the pressure control valves 20FL to 20RR is a pilot operation type having a valve housing having a spool slidably housed in a cylindrical insertion hole, and a proportional solenoid provided integrally with the valve housing. Is formed.
The supply port and return port for the hydraulic oil of the pressure control valves 20FL to 20RR are communicated with the hydraulic oil supply side and the hydraulic oil return side of the hydraulic power source 22 through hydraulic pipes 38 and 39, and the output port is connected through the hydraulic pipe 40. Pressure chamber L of hydraulic cylinders 18FL-18RR
Of each other.

Therefore, by controlling the value of the exciting current I as a command value supplied to the exciting coil of the proportional solenoid, the output pressure P corresponding to the exciting current I is output from the output port to the pressure chamber L of the hydraulic cylinder 18FL (to 18RR). Can be supplied to. That is, as shown in FIG. 3, the output pressure P becomes the minimum pressure P _MIN when the exciting current I has its minimum value I _MIN , and when the exciting current I is increased to its maximum value I _MAX , the output pressure P becomes a predetermined value. The output pressure P increases to the maximum value P _MAX with a proportional gain. P _MAX is the pressure of hydraulic source 22.

On the other hand, the first and second lateral acceleration sensors 26a, 26b are, as shown in FIG. 4, separated by a distance a, b (a>
b) are respectively arranged at the front positions, the lateral acceleration acting on the vehicle body is sensed at the respective positions, and the controller 3 outputs the lateral acceleration detection signals g _a and g _b , which are voltage signals corresponding thereto.
It is designed to output to 0. Here, as shown in FIG. 5, the lateral acceleration detection signals g _a and g _b are positive when the vehicle is steered to the right from a straight traveling state, and negative when the vehicle is steered to the left,
Moreover, it is almost directly proportional to the lateral acceleration value.

Each of the vehicle height sensors 28FL to 28RR is composed of a potentiometer or the like, and is interposed between the wheel side member 12 and the vehicle body side member 14 in parallel with the hydraulic cylinders 18FL to 18RR. And each sensor 28FL-28RR is a cylinder tube
18a and controller vehicle height signals h _{i (i} = 1~4) consisting of a voltage signal directly proportional to the relative displacement between the piston rod 18b
Supply 30 each.

As shown in FIG. 6, the controller 30 includes A / D converters 50A, 50B, 52A to 52D for digitizing the input lateral acceleration signals g _a , g _b and the vehicle height signal h _i , and the A / D converters A / D. D converter 50A, 50B, 5
A microcomputer 54 for inputting the output signals of 2A to 52D to perform calculation and control, and D / A converters 56A to 56D for analogizing the output control signal SC of the microcomputer 54,
Excitation current I _i according to the output signals of the D / A converters 56A to 56D
It has drive circuits 58A to 58D for supplying (i = 1 to 4) to the pressure control valves 20FL to 20RR.

Among them, the microcomputer 54 is configured to include at least an interface circuit 60, an arithmetic processing device 62, and a storage device 64. The arithmetic processing unit 62 reads each detection signal through the interface circuit 60, and performs a predetermined process (first process) on the basis of a predetermined program stored in the storage device 64 in advance.
11 to 13), and outputs the control signal SC via the interface circuit 60 as needed. The storage device 64 stores programs and fixed data necessary for executing the processing of the arithmetic processing device 62, and can temporarily store the processing result.

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

First, set the lateral acceleration sensor to a distance e from the center of gravity of the vehicle.
The detection operation of the sensor when it is arranged only in front of
The two-degree-of-freedom model of the vehicle shown in the figure (for simplicity, the left and right wheels are replaced by one wheel) is analyzed.

First, vehicle weight: M, yaw moment of inertia around center of gravity: I, wheelbase: l, distance between front wheels and center of gravity: a, distance between rear wheels and center of gravity: b, vehicle speed: V, cornering power of front wheels: C ₁ , rear wheels If the cornering power is C ₂ , the front wheel actual steering angle is δ, and the lateral displacement of the center of gravity is y, the basic equation is M (+ V) = f ₁ + f ₂ …… (1) I = af ₁ + bf ₂ …. … (2) However, the front wheel cornering force f ₁ and the rear wheel cornering force f ₂ are Is. Where + V is the lateral acceleration of the center of gravity, is the yaw rate, δ− (a +) / V is the front wheel side slip angle, − (
-B) / V is the rear wheel side slip angle, β = y / V is the center of gravity point side slip angle, and the angle is positive in the counterclockwise direction.

Therefore, when the lateral acceleration + V and the yaw rate with respect to the actual steering angle δ are obtained by Laplace transforming the equations (1) and (2), the following equations (4) and (5) are obtained.

However, ω _n = (l / V) [(C ₁ C ₂ (1 + K _s V ² ) / IM] ^1/2 ω ₂ = (lC ₂ / I) ^1/2 , ζ ₂ = (b / 2V) · (lC ₂ / I) ^1/2 ,
τ ₁ = (aMV) / lC ₂ , where K _s = (M / l ² ) (b / C ₁
-A / C ₂ ).

Therefore, when the lateral acceleration sensor is installed as shown in FIG. 7, the lateral acceleration sensed by the sensor is a value obtained by adding the lateral acceleration + V at the center of gravity to the lateral acceleration e generated by the yaw angular acceleration. So, after all, + V
+ E.

Therefore, the lateral acceleration (= + V + e) sensed by the lateral acceleration sensor with respect to the lateral acceleration (= + V) at the center of gravity.
), The transfer function of the ratio is G (s), Becomes The gain and phase characteristics for the equation (6) are examined with the vehicle speed V and the separation distance e as parameters.
These are shown in FIGS. (A) and (b) and FIGS. 9 (a) and (b), respectively.

According to this, for both gain and phase characteristics, the larger the distance e is, the larger the gain and the phase advance are improved, and the larger the vehicle speed V is, generally, the characteristics are 1 to 2 Hz.
It can be seen that the phase advance is greatly improved for the fast steering of.

On the other hand, the roll rate characteristic with respect to the actual steering angle δ is
As shown in FIGS. (A) and (b), it changes depending on the steering frequency and the distance e. Since the steering frequency is 2 Hz or less except for a racing vehicle, there is an appropriate value for the distance e in order to reduce / δ in the steering frequency range that is frequently used. This appropriate value varies depending on the vehicle specifications, but in the case of general passenger cars, it is important to be less than 1Hz from the frequency of use,
As shown in FIG. 10 (a), if the distance e is made too large, the roll gain becomes rather large. Therefore, an appropriate value is around e = 20 to 40 cm.

Next, the processing in the controller 30 will be described. When the ignition switch is turned on, the controller
30 starts, a predetermined main program is executed, and along with the execution, a timer interrupt process shown in FIG. 11 to FIG. 13 is performed every predetermined time (for example, 20 msec).

FIG. 11 is processed every wheel 10FL to 10RR and every predetermined time, and in step, it is judged whether or not it is the first interrupt processing after starting. If this process is "YES",
The process proceeds to step, and the exciting current I _Hi (i = 1 to 4) is set to _IN corresponding to the neutral pressure P _N as an initial value, and the process returns to the main program.

On the other hand, if the judgment in step is "NO",
Load the appropriate sensor value h _i of the vehicle height sensors 28FL~28RR in step, and calculates the vehicle height H _i from the memory table or the like in step. Then, the process proceeds to step, and the vehicle height value H _i is compared with the reference vehicle height value H _o (for example, the vehicle height value when the vehicle is in the standard loading state, and the neutral pressure P _N ). Therefore, when H _i ≠ H _o, the vehicle height flag F _i (i = 1 to 4) indicating whether or not the vehicle height value H _i is equal to the reference value H _o is lowered in the step, and the process proceeds to the step.

In this step, it is judged whether H _i > H _o , and H _i > H
_{If o} , return to step; if H _i > H _o , return through step. That is, in the step, in order to increase the cylinder pressure P and increase the vehicle height value H _i , the exciting current I _Hi
Is increased by a minute value ΔI. On the contrary, in step, in order to lower the cylinder pressure P and lower the vehicle height value H _i , the exciting current I _Hi is decreased by a minute value ΔI.

On the other hand, if H _i = H _o in the step, the vehicle height flag F _i is set in the step and the process returns to the main program.

Therefore, by executing the processing in FIG. 11, in order to gradually adjust this in accordance with the vehicle height H _i of that time to the reference value H _o, the value of the exciting current I _Hi is updated. Then, after reaching the reference value H _o is excitation current I _Hi at arrival it is maintained.

Next, the processing of FIG. 12 will be described. In step, it is determined whether or not H _i = H _o for the four wheels 10FL to 10RR based on whether or not the vehicle height flag F _i described above is “1”. If H _i = H _o is not found in all positions of the four wheels 10FL to 10RR by this judgment, it returns to the main program as it is and all positions are
Wait until H _i = H _o .

Then, if "YES" is determined in the step, the cylinder pressures P _{FL to} P _RR of the hydraulic cylinders 18FL to 18RR are calculated from the value of the exciting current I _Hi set at that time in the step in FIG. It is calculated by referring to the storage table corresponding to. Next, move to the step, and the front-rear load ratio η
Is calculated from the equation η = (P _RL + P _RR ) / (P _FL + P _FR ). Then, the process proceeds to step, the lateral acceleration calculation position x is obtained by referring to the storage table stored in advance corresponding to FIG. 14, and thereafter, the process returns to the main program.

In other words, by executing the processing in Figure 12, it is converted to cylinder pressure P _FL to P _RR of each hydraulic cylinder 18FL~18RR by the product vehicle state of the occupant number or the like to hold the reference vehicle height value H _o, The lateral acceleration calculation position x is determined based on this conversion value.

Next, the processing of FIG. 13 will be explained.
Reads the lateral acceleration signals g _a and g _b in step, calculates the lateral acceleration G _a and G _b at each sensor installation position from the signal signals g _a and g _b read in step by referring to a memory table, etc. Move to.

In the step, the lateral acceleration at the lateral acceleration calculation position x determined in the step of FIG.
G _x , based on the calculated values in the step of FIG. 13, It is calculated by the formula.

Then, the process proceeds to step, and the pressure control valve 20FL ~
The total exciting current I _i (i = 1 to 4) supplied to the 20RR is calculated by the formula of I _i = G _x · K + I _Hi . Here, K is a predetermined proportional gain.

Next, the processing unit 62 shifts the control signal SC corresponding to the calculation in the step to the D / A converter 56A (~
56D) and then returns to the main program.

Control signal SC analog-converted by D / A converters 56A to 56D
Is amplified by the drive circuits 58A to 58D, and the corresponding pressure control valves 20FL to 20RR are generated as the exciting current I _i calculated as described above.
Is supplied to each proportional solenoid.

That is, by executing the processing of FIG. 13, the lateral acceleration at the lateral acceleration calculation position is calculated, and the roll suppression and the vehicle height adjustment according to the calculated value are executed.

 Next, the overall operation will be described.

First, when the suspension 16 starts up, the hydraulic cylinder
The cylinder pressures of 18FL to 18RR are set to neutral pressure P _N for the time being (step in FIG. 11), and vehicle height adjustment is started from the vehicle height value based on this neutral pressure P _N (steps in FIGS. 11 and 13). . As a result, when all the vehicle height values H _i at the positions of the wheels 10FL to 10RR reach the reference value H _o , the lateral acceleration calculation position is set as the distance x in front of the center of gravity (12th position).
See figure).

Now, assuming that the vehicle is traveling straight on a flat road with no unevenness on the road surface, in this state, there is no roll in the vehicle body, so the first and second lateral acceleration sensors 26a, 26b
The values of the detection signals g _a and g _b are substantially zero. Therefore, the exciting current I _i output from the controller 30 is a component for maintaining the vehicle height.
It becomes I _Hi , and the car body is supported almost flat.

If, for example, the vehicle makes a right turn traveling at a predetermined speed from the straight traveling state described above, the vehicle body tries to roll to the left as viewed from the rear side. At this time, the values of the detection signals g _a and g _b of the first and second lateral acceleration sensors 26a and 26b are positive, and the lateral acceleration G _x at the lateral acceleration calculation position x that is sequentially set also has a positive value. As described above, the calculated lateral acceleration G _x includes a value obtained by adding the lateral acceleration + V at the center of gravity at that time point to the compensation component x which is the phase lead component due to the yaw angular acceleration.

Then, based on this compensated lateral acceleration G _x , the exciting currents I _i are calculated and supplied so that the cylinder pressure changes of the hydraulic cylinders 18FL to 18RR are opposite on the left and right. As a result, the output pressure P of the left pressure control valves 20FL, 20RL increases, and the cylinder pressure of the left hydraulic cylinders 18FL, 18RL increases accordingly. As a result, a cylinder biasing force that opposes the contracting force is generated, and the anti-roll effect is exhibited. However, the output pressure P of the right pressure control valves 20FR, 20RR decreases, and the cylinder pressure of the right hydraulic cylinders 18FR, 18RR decreases accordingly. That is, although the cylinders 18FR and 18RR are in a state of being expanded by the roll, the cylinder pressure is controlled to a biasing force that does not promote the expanding force due to the decrease in the cylinder pressure.

Conversely, when the vehicle turns left, for example, from the straight running state, the vehicle body tends to roll to the lower right as viewed from the rear side. However, in this case, the value of the calculated lateral acceleration G _x becomes negative, and in the end, it is controlled opposite to the above, and the anti-roll effect is obtained.

In this way, the anti-roll effect is obtained, but at that time, the lateral acceleration G _x used for roll suppression is a value at a position in front of the center of gravity of the vehicle. Therefore, the detection sensitivity is increased by the lateral acceleration component x due to the yaw angular acceleration, and it acts as a phase lead element. Therefore, the lateral acceleration component x compensates for the response delay of the pressure control valve and the delay of the control system due to the calculation time. To be done. Therefore, compared with the conventional case where the lateral acceleration sensor is installed at the center of gravity of the vehicle, the delay in roll rigidity control is improved and the accuracy is also improved, so that the roll can be suppressed more accurately and a stable vehicle posture is maintained. Can be held.

Further, for example, when the number of passengers of the vehicle and the load amount increase and the center of gravity moves to the rear of the vehicle, the lateral acceleration calculation position x
Is set to be smaller, that is, closer to the center of gravity, and the lateral acceleration G _x at this position is calculated in the same manner as described above. On the contrary, when the center of gravity moves forward due to a decrease in the load, the distance x increases and the lateral acceleration calculation position also moves forward. By adjusting in this way, even if the position of the center of gravity changes,
When the acting lateral acceleration is the same, the lateral acceleration is almost the same G _x
Is calculated, the roll suppression characteristic becomes almost constant,
The occupants will not feel useless.

Further, in this embodiment, two lateral acceleration sensors are provided,
Since the lateral acceleration at the actual desired position depends on the calculation, it is possible to provide the two lateral acceleration sensors at positions according to the vehicle structure, for example, by mounting the two lateral acceleration sensors while avoiding the shift lever position of the transmission, There is also an advantage that the freedom of mounting the sensor is increased.

In the present embodiment, the process of step of FIG. 12 corresponds to the loaded state detecting means, the process of step of FIG. 12 corresponds to the lateral acceleration calculation position changing means, and the A / D converters 50A and 5A are provided.
0B and the processing of steps 1 to 3 in FIG. 13 constitute lateral acceleration calculating means, and the processing of step 1 in FIG. 13, D / A converters 56A to 56D, and drive circuits 58A to 58D constitute command value calculating means. ing.

Incidentally, the lateral acceleration calculating means in the above embodiment is set in advance so as to calculate the lateral acceleration at a predetermined position in front of the center of gravity, and the loading state detecting means and the lateral acceleration calculating position changing means are set as necessary. It may be installed, and the active suspension according to claim 1 is constituted by this.

Further, as the loaded state detection means in the present invention, in addition to the above-mentioned configuration, for example, a load sensor is provided in each actuator, and the loaded state is directly grasped as a load value at each wheel 10FL to 10RR position. The lateral acceleration calculation position can also be determined from this sensor value in the same manner as described above.

Further, in the above-described embodiment, the case where the roll rigidity control is performed independently has been described. However, the same control can be performed when the pitch suppression control and the bounce suppression control are appropriately combined and controlled.

Furthermore, in the above-mentioned embodiment, the case where the hydraulic cylinder is applied as the actuator has been described, but the present invention may also apply other fluid pressure cylinders such as a pneumatic cylinder. Similarly, the actuator control means is not limited to the pressure control valve, and may be a flow control servo valve as long as the actuator is a flow control type cylinder.

Furthermore, the controller 30 in the above embodiment is
It can also be configured by combining with an electronic circuit such as a variable gain amplifier, an adder, and a subtracter.

〔The invention's effect〕

As described above, in the device according to claim 1 of the present invention, the lateral acceleration that acts on the vehicle is detected based on the detection values of the two lateral acceleration sensors arranged in the front-rear direction of the vehicle.
Since it was determined as a calculated value corresponding to the lateral acceleration calculation position in front of the center of gravity of the vehicle, the calculated lateral acceleration is
In addition to the lateral acceleration at the center of gravity at that time, the lateral acceleration component that is the product value of the yaw angular acceleration and the distance between the center of gravity and the calculated position is also detected. By compensating for the phase delay of the control system, this makes it possible to obtain a significantly superior anti-roll effect compared to conventional control.
It is possible to secure a stable vehicle posture. In addition, even when a device such as a transmission is mounted at the lateral acceleration calculation position,
Due to the restrictions imposed by these devices, it is possible to eliminate the situation in which the lateral acceleration sensor has to be arranged at a position outside this position, and the detection accuracy must be reduced, while the two lateral acceleration sensors used for the calculation are eliminated. Has the effect that it can be arranged freely.

Further, in the device according to claim 2, since the configuration for changing and setting the lateral acceleration calculation position according to the loaded state is added to the configuration according to claim 1, the above-described advantages can be enjoyed as they are, and the number of passengers, Even if the load amount changes, the roll restraining characteristic can be maintained substantially constant, and the effect of eliminating the feeling of discomfort and anxiety that is conventionally given to the occupant due to the change in the loading condition can be obtained.

[Brief description of drawings]

1 (a) and 1 (b) are views corresponding to the claims of the present invention, FIG. 2 is a schematic configuration diagram showing an embodiment of the present invention, and FIG. 3 is an exciting current of a pressure control valve. FIG. 4 is a graph showing the output pressure, FIG. 4 is an explanatory view showing the arrangement position of the lateral acceleration sensor, FIG. 5 is a graph showing the detection characteristics of the lateral acceleration sensor, and FIG. 6 is a block diagram showing the configuration of the controller. FIG. 8 is an explanatory view showing the arrangement position of the lateral acceleration sensor in the two-degree-of-freedom model of the vehicle, and FIGS. 8A and 8B are the transfer functions of the lateral acceleration sensor's detected lateral acceleration to the lateral acceleration at the center of gravity. The gain and phase characteristic diagrams when the vehicle speed in Fig. 9 is used as a parameter, and Figs. 9A and 9B each use the installation distance in the response transfer function of the lateral acceleration detected by the lateral acceleration sensor with respect to the lateral acceleration at the center of gravity as a parameter. Gain and phase characteristics 10 (a) and 10 (b) are gain and phase characteristic diagrams of the roll rate response transfer function with respect to the actual steering angle, and FIGS. 11 to 13 are schematic flowcharts showing the processing procedure executed in the controller, respectively. FIG. 14 is a graph showing an example of the lateral acceleration calculation position with respect to the longitudinal load ratio. In the figure, 12 is a wheel side member, 14 is a vehicle body side member, 16 is an active suspension, 18FL-18RR are front left to rear right hydraulic cylinders,
20FL to 20RR are front left to rear right pressure control valves, 26a and 26b are first and second lateral acceleration sensors, 28FL to 28RR are vehicle height sensors, and 30 is a controller.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshi Fujimura, 2 Takara-cho, Kanagawa-ku, Yokohama, Kanagawa Nissan Motor Co., Ltd. (72) Masaharu Sato, 2 Takara-cho, Kanagawa-ku, Yokohama, Nissan Nissan Motor Co., Ltd. (56) References JP-A-61-218413 (JP, A) JP-A-61-181713 (JP, A) Actually developed JP-A-62-181411 (JP, U)

Claims (2)

(57) [Claims] 1. An actuator interposed between a vehicle body and a wheel, and an actuator control means for controlling an operating state of the actuator according to a command value that can be changed, and according to a lateral posture change of the vehicle body. In the active suspension in which the command value is changed and controlled, first and second lateral suspensions which are arranged apart from each other in the front and rear of the vehicle and which detect accelerations acting in the lateral direction of the vehicle body at the installation positions are provided. An acceleration sensor, a lateral acceleration calculating means for calculating a lateral acceleration at a desired calculation position in front of the center of gravity of the vehicle based on the detection values of the first and second lateral acceleration sensors, and a calculated value of the lateral acceleration calculating means. And a command value computing means for computing the command value according to the above and giving the command value to the actuator control means. 2. An actuator interposed between a vehicle body and wheels, and actuator control means for controlling an operating state of the actuator according to a command value that can be changed, and according to a lateral posture change of the vehicle body. In the active suspension in which the command value is changed and controlled, first and second lateral suspensions which are arranged apart from each other in the front and rear of the vehicle and which detect accelerations acting in the lateral direction of the vehicle body at the installation positions are provided. An acceleration sensor, a lateral acceleration calculating means for calculating a lateral acceleration at a changeable calculation position in front of the center of gravity of the vehicle based on the detection values of the first and second lateral acceleration sensors, and calculation of the lateral acceleration calculating means. A command value calculating means for calculating a command value according to the value and giving the command value to the actuator control means, a vehicle state detecting means for detecting a vehicle state, and a vehicle state by the vehicle state detecting means. Active suspension, characterized in that equipped with a lateral acceleration calculating position changing means for changing the calculated position by the lateral acceleration calculating means in response to broadcast.