JPH0195923A - Active type suspension device - Google Patents

Abstract

PURPOSE:To accurately control a suspension by setting a mean value of lateral or longitudinal acceleration, acting on a car body, as the neutral value and calculating a difference value between this mean value and each acceleration so as to correct the acceleration. CONSTITUTION:A suspension A adjusts the relative displacement between a car body and a wheel in accordance with a predetermined instruction value. While a means B detects or longitudinal acceleration acting on the car body. And in accordance with each detected acceleration, the above described instruction value is controlled. In this device, a means C calculates a mean value of each acceleration. While in a means D, the calculated mean value is set as the neutral value of the lateral or longitudinal acceleration. Further in a means E, a difference value between the set neutral value and the lateral or longitudinal acceleration is calculated. And in a means F, the instruction value corresponding to the calculated difference value is formed. Thus accurately correcting a zero point of the acceleration detection value, a proper control is performed.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is directed to a vehicle in which a fluid pressure cylinder is inserted between a vehicle body and wheels, and the working fluid pressure of this fluid pressure cylinder is controlled in accordance with lateral acceleration or longitudinal acceleration. The present invention relates to an active suspension device that controls characteristics such as pitch stiffness and roll stiffness of a vehicle.

[Conventional technology]

An example of this type of active suspension device is the one described in Japanese Patent Application No. 137875/1987, which was previously proposed by the present applicant.

In this prior application, an acceleration detection means having a sensor for detecting lateral acceleration or longitudinal acceleration acting on a vehicle body, a control means for forming a command value according to a detected value by this acceleration detection means, and a control means for forming a command value according to a detected value by this acceleration detection means are provided. A configuration is disclosed that includes a pressure control valve that outputs a pressure corresponding to a command value, and a hydraulic cylinder that is inserted between the wheels and the vehicle body and whose operating pressure changes by being energized by the output pressure of the pressure control valve. ing. The roll stiffness and the pitch stiffness are changed based on the detected value of acceleration, so that changes in the posture of the vehicle body can be appropriately suppressed.

(Problem to be solved by the invention) However, in the technology described in the earlier application, no consideration was given to data processing to correct the zero point of the detected value of the lateral acceleration sensor or the longitudinal acceleration sensor, so temperature drift A situation may occur where the detected value of a sensor whose zero point is shifted due to output errors such as DC offset due to In addition, variations in the detection characteristics of the above-mentioned sensors and variations in sensitivity of other axes due to angular errors when mounting on the vehicle body were not taken into account, so the zero point of the acceleration detection value varied from vehicle to vehicle. There is also an unresolved problem that suspension control that includes this variation is performed.

On the other hand, if you try to avoid these problems in advance, you will need to conduct a more rigorous inspection of the sensor's detection characteristics before installing it on the car body, or you will have to set the angle more precisely when installing the sensor on the car body. However, there was an unresolved problem that this process required a lot of time and effort, resulting in an increase in production costs.

Therefore, this invention was made in view of such unresolved problems, and the average value of lateral acceleration or longitudinal acceleration is set as a neutral value, and the difference value between this average value and lateral acceleration or longitudinal acceleration is calculated. By calculating the acceleration and performing suspension control using this corrected acceleration, it is possible to accurately correct the zero point of the detected acceleration value and perform more appropriate control based only on the actually occurring acceleration. The object of the present invention is to provide an active suspension that can increase the angle error range of the detection characteristics and mounting of the sensor alone, and contribute to reducing production costs.

[Means for solving problems]

In order to achieve the above object, the present invention provides a suspension that can adjust the relative displacement between the vehicle body and the wheels according to a predetermined command value, and a lateral acceleration acting on the vehicle body, as shown in the basic configuration diagram of FIG. Alternatively, in an active suspension device comprising a lateral acceleration or longitudinal acceleration detection means for detecting longitudinal acceleration, and controlling the command value according to the lateral acceleration or the longitudinal acceleration, average value calculation means for calculating an average value; neutral value setting means for setting the average value as a neutral value of the lateral acceleration or the longitudinal acceleration; and a difference value between the neutral value and the lateral acceleration or the longitudinal acceleration. The apparatus includes an acceleration correction means for calculating, and a command value forming means for forming the command value corresponding to the difference value.

[Effect]

In this invention, the lateral acceleration or longitudinal acceleration acting on the vehicle body is detected by the lateral acceleration or lateral acceleration detection means, and the detected values are appropriately averaged by the average value calculation means. This average value is almost close to the detection error component inherent to the acceleration detection means. Therefore, the average value is set as the neutral value of the lateral acceleration or longitudinal acceleration by the neutral value setting means, and assuming that the difference between this neutral value and the lateral acceleration or longitudinal acceleration is the acceleration that actually occurs, the difference value is Calculated by acceleration correction means. Then, the command value forming means forms a command value according to the corrected acceleration, that is, the difference value, and outputs the command value to the suspension. The suspension controls the relative displacement between the vehicle body and the wheels according to the command value, thereby more accurately suppressing changes in the vehicle body posture.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

FIGS. 2 to 6 are diagrams showing an embodiment of the present invention. The suspension control in this embodiment is a case in which a change in attitude of the vehicle in the lateral (left and right) direction is suppressed.

First, in FIG. 2, 10 indicates a vehicle body side member (suspension arm), IIPL to IIRR indicate front to rear right wheels, and 12 indicates an active suspension device.

The active suspension device 12 includes each wheel 11FL-1.
Hydraulic suspensions 14FL to 14RR are individually equipped to correspond to 1RR, and this suspension 14F
A hydraulic power source 16 for the L-14RR, accumulators 18, 18 for accumulating pressure inserted between the hydraulic power source 16 and the suspensions 14FL-14RR, and a lateral acceleration sensor 20 for detecting lateral acceleration acting in the lateral direction of the vehicle body. , the suspension 1 according to the detected value of the lateral acceleration sensor 20.
It has a controller 22 that individually controls the 4FL-14RR.

Among these, each of the suspensions 14FL-14RR is
Hydraulic cylinders 26FL to 26RR as fluid pressure cylinders interposed between the vehicle body side member lO and each wheel side member 24 of wheels 11FL to IIRR, and pressures for adjusting the working oil pressure of these hydraulic cylinders 26FL to 26RR, respectively. It is configured to include control valves 28FL to 28RR. Further, each of the pressure chambers of the hydraulic cylinders 26FL to 26RR, which will be described later, is connected to an accumulator 34 for vibration absorption via a throttle valve 32, as shown in the figure. Furthermore, a coil spring 36 having a relatively low spring constant and supporting the static load of the vehicle body is disposed between the vehicle body and the wheels of each of the hydraulic cylinders 26FL to 26RH.

Each of the hydraulic cylinders 26FL to 26RR has a cylinder tube 26a, and a lower pressure chamber separated by a piston 26c is formed in the cylinder tube 26a. Then, the lower end of the cylinder tube 26a is attached to the wheel side member 24, and the piston rod 26a is attached to the wheel side member 24.
The upper end of 6b is attached to the vehicle body side member 10. Further, the pressure chamber is connected to the pressure control valve 2 through a hydraulic pipe 38, which is partially provided in the axial direction inside the piston rod 26b.
It communicates with the input/output ports 8PL to 28RR, so that the hydraulic pressure in the pressure chamber can be controlled. Here, 52.54 is the hydraulic power source 16 and the pressure control valve 2.
This is the piping for operation, hydraulic oil feed, and return between 8FL and 28RR.

Further, each of the pressure control valves 28FL to 28RR is formed in a biloft type having a cylindrical valve housing and a proportional solenoid integrally provided with the valve housing. By controlling the value of the control current I as a command value supplied to the excitation coil of the proportional solenoid, the output pressure P from the input/output port to the hydraulic cylinders 26FL to 26RR can be adjusted as shown in FIG. It has become. That is, when the control current ■ is at its neutral value IN, the output pressure P becomes its neutral pressure PM (that is, the off-cent pressure), and the control current ■ reaches its maximum value ■ from the neutral value ■8. When the minimum value I increases in the X direction or decreases in the NIN direction, the output pressure P becomes proportional to the value ■, and as a result, an urging force is generated in the pressure chambers of the hydraulic cylinders 26FL to 26RR to resist changes in the attitude of the vehicle body. be done. Here, P MAX is the saturated output pressure of the hydraulic power source 16, and pHll is set to a value that takes into account the noise of the control current ■.

On the other hand, the above-mentioned lateral acceleration sensor 20 is installed at a predetermined position slightly forward of the center of gravity of the vehicle, and this lateral acceleration sensor 20 detects the lateral acceleration GV during turning, etc. A lateral acceleration signal gv, which is a voltage signal, is output to the controller 22.

In other words, as shown in FIG. 4, the lateral acceleration signal gv takes a positive predetermined neutral value gvs when the lateral acceleration GY is zero,
When a positive lateral acceleration GV occurs, it increases from the neutral value gVN, and when a negative lateral acceleration -G occurs, the neutral value g
It is set to decrease from vx.

Here, the lateral acceleration Gv that acts when the vehicle turns to the right is positive, and the lateral acceleration G that acts when the vehicle turns to the left is negative.

Furthermore, the controller 22, as shown in FIG.
A microcomputer 70, an A/D converter 71 that converts an input analog lateral acceleration signal gv into a digital value and outputs it to the microcomputer 70, and a digital control signal S output from the microcomputer 70.
D/A converters 73A to 73D that convert c into an analog quantity
and drive circuits 74A to 74D that individually output control currents I according to the outputs of the D/A converters 73A to 73D to the pressure control valves 28FL to 28RR.
- Of these, the microcomputer 70 includes at least an interface circuit 76, an arithmetic processing unit 78, a RAM, and an R
The interface circuit 76 is configured to include a storage device 80 consisting of an OM or the like, and the interface circuit 76 is configured to include 10 ports and the like. Further, the arithmetic processing unit 78 reads the lateral acceleration signal gv via the interface circuit 76 and performs the arithmetic operations shown in FIG. Predetermined programs, fixed data, etc. necessary for the execution of are stored in advance, and processing results of the arithmetic processing unit 78 can be stored.

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

When the ignition switch of the vehicle is turned on, the power to the controller 30 is also turned on, and the microcomputer 70 executes the processing of a predetermined main program, and also executes the timer interrupt processing shown in FIG. 6 at predetermined intervals (for example, 20 m5ec). Execute.

First, in step (2) in FIG. 6, the processing unit 78 of the microcomputer 70 reads the lateral acceleration signal gv applied to the lateral acceleration sensor 20 via the A/D converter 71, and then in step The lateral acceleration GV corresponding to is calculated, and the process moves to step (3).

In this step (2), the average value GVAV of the lateral acceleration GV is calculated for each interrupt process based on the moving average process. This average value Gvav approximates the inherent error due to the DC offset of the lateral acceleration sensor 20 and the angular error in the mounting.

Next, the process moves to step (2), and it is determined whether the average value G Yav calculated in step (2) is smaller than a predetermined value α (for example, 0.02G). This judgment is based on the average value G YAV
The purpose is to determine whether the α value is less than a value that can actually be taken when driving on a normal road, and the α value is determined based on experiments etc. to meet the purpose.

Therefore, if GvAv<α in step (2), it is assumed that there is no abnormality in the lateral acceleration sensor 20 and its detection path, and the process moves to step (2). In this step ■, the average value G , , v calculated in step ■ is converted to the neutral value GY of the lateral acceleration GV.
II, and then proceed to step (2).

On the other hand, if GVAv≧α in step (2), it is assumed that some abnormality has occurred in the lateral acceleration sensor 20 and its detection path, and the process moves to step (2) a. And step a
Now, in order to forcibly fix the neutral value cyo as part of fail-safe, a preset constant value β is set, and the process moves to step (2). Here, the β value is selected to be a value that does not hinder suspension control, for example, corresponds to OG.

Next, in step ■, the value Gy calculated in step ■
The neutral value Gvo set in step (2) or (2) a is subtracted from the neutral value Gvo, and this is used as the corrected lateral acceleration signal GvO value. In other words, through this correction calculation, the lateral acceleration GV that actually acts on the vehicle body in accordance with the driving condition can be obtained.

Next, the process moves to step (2), and the value of the control current (2) is calculated by multiplying the lateral acceleration GVO value corrected in step (2) by a predetermined gain Kv. At this time, the value of the control current I is calculated individually so that the outer wheel side and the inner wheel side have opposite roll stiffness characteristics during cornering.

Next, in step (2), the control signal SC corresponding to the value of the control current (2) calculated in step (2) is applied to the pressure control valve 28.
Output to FL-28RR individually and return to the main program.

Therefore, the control signals SC set and output as described above are individually converted into analog quantities by D/A converters 73A to 73D, and then output to drive circuits 74A to 74D. The control current (2) having the value set as described above is supplied from the drive circuits 74A to 74D to the front and rear right pressure control valves 28FL to 28RR, respectively.

Therefore, when the vehicle is running at a constant speed on a flat, good road and the actual lateral acceleration Gv is zero, the control current I that has undergone the process shown in FIG. When installed, the value will be slightly deviated from the neutral value ■8 which is corrected for the error due to the angle error.Correspondingly, the output pressure P of the pressure control valves 28FL to 28RR, that is, the pressure of the hydraulic cylinders 26FL to 26RR. The pressure in the chamber is at its neutral value P
, to maintain a neutral state of the suspension by raising and lowering it more slightly.

On the other hand, assume that the vehicle turns to the right, for example, and rolls so that the left side of the vehicle sinks when viewed from the rear of the vehicle.

In this state, the control current
is the value after the above-mentioned correction, and the output pressure P of the pressure control valves 28FL and 28RL on the outer ring side rises from the neutral pressure PM, and the pressure control valve 28FR on the inner ring side rises.

28RR is reduced from the neutral pressure PM. As a result, the hydraulic cylinders 26PL and 26RL on the outer wheel side generate a biasing force that resists sinking of the vehicle body, and the hydraulic cylinders 26FR and 26RR on the inner wheel side prevent the vehicle body from lifting up and maintain the lateral posture of the vehicle body. Changes are accurately suppressed and controlled. This also applies when the vehicle turns left.

Furthermore, due to some abnormality occurring in the lateral acceleration sensor 20 and its detection path while driving, the lateral acceleration Gv
Even if the average value of G YAV reaches a value that cannot be achieved in reality, the neutral value cyo of the lateral acceleration G7 is forcibly fixed to a value that is assumed to be safe, and there is no possibility that running itself will be hindered. Failsafe is executed accurately to ensure that no problems occur.

Here, the lateral acceleration sensor 20. Steps in Figure 6■,■
A lateral acceleration detection means is formed by the process of step (2) in the same figure, an average value calculation means is formed by the process of step (2) in the same figure, a neutral value setting means is formed by the process of step (2) in the same figure, and a means for setting a neutral value is formed by the process of step (2) in the same figure. The acceleration correction means is formed by the above steps, and the command value forming means is formed by the processing of steps ① and ② in the figure.

In the above embodiment, a case has been described in which the roll stiffness is controlled by detecting the lateral acceleration, but the present invention is not necessarily limited to this, and for example, the pitch is determined by detecting the acceleration in the longitudinal direction of the vehicle body. The bounce suppression control may be performed by controlling the rigidity or by detecting the acceleration in the vertical direction, or by appropriately combining these methods.

Further, in the above embodiment, moving average processing is performed in the process of step (2) in FIG. 6, which is the average value calculation means, to reduce the memory capacity occupied, but the invention is not necessarily limited to this. , for example, may be a simple average of a predetermined number of lateral accelerations.On the other hand, the sampling period of the lateral acceleration may be determined every certain distance traveled by the vehicle, in addition to the certain time period required for timer interrupt processing as in the above embodiment. You may also do so.

Furthermore, in the embodiment described above, a case has been described in which a hydraulic cylinder is used as the suspension, but the present invention is not limited to this, and other fluid pressure cylinders such as an air cylinder can be applied.

Furthermore, the controller in the embodiment 422
can also be constructed entirely of electronic circuits such as counters, comparators, amplifiers, etc.

(Effects of the Invention) As explained above, according to the present invention, the average value of lateral acceleration or longitudinal acceleration is set as a neutral value, and the difference value between this average value and lateral acceleration or longitudinal acceleration is calculated. Since the acceleration is corrected and suspension control is performed using this corrected acceleration, the zero point of the detected acceleration value can be accurately corrected using the average value that is considered pseudo-neutral position information, and only the acceleration that is actually occurring can be corrected. On the other hand, even if there are variations in the detection characteristics of the lateral acceleration or longitudinal acceleration detection means and the installation of the vehicle body, corrections can be made to accurately absorb the variations in each vehicle. Therefore, its detection characteristics and installation can expand the angle error range, which has the excellent effect of promoting labor saving in inspection and manufacturing processes and contributing to production cost reduction.

[Brief explanation of the drawing]

Fig. 1 is a basic configuration diagram showing an overview of the present invention, Fig. 2 is a schematic configuration diagram showing an embodiment of the invention, and Fig. 3 is a diagram showing the relationship between the control current ■ supplied to the pressure control valve and its output pressure P. 4 is a graph showing the detection characteristics of the lateral acceleration sensor, FIG. 5 is a block diagram of the controller, and FIG. 6 is a flowchart showing the processing procedure for the lateral acceleration detection signal executed in the controller. In the figure, 10 is a vehicle body side member, 12 is an active suspension system ff, 14FL to 14RR are suspensions, 20 is a lateral acceleration sensor, 22 is a controller, 24 is a wheel side member, 26FL to 26RR are front to rear right hydraulic cylinders, 2
8FL to 28RR are front to rear right pressure control valves.

Claims (1)

[Claims] (1) A suspension capable of adjusting the relative displacement between the vehicle body and the wheels according to a predetermined command value, and a lateral acceleration or longitudinal acceleration detection means for detecting lateral acceleration or longitudinal acceleration acting on the vehicle body, Alternatively, in an active suspension device configured to control the command value according to the longitudinal acceleration, an average value calculating means for calculating an average value of the lateral acceleration or the longitudinal acceleration; neutral value setting means for setting a neutral value of longitudinal acceleration; acceleration correction means for calculating a difference value between the neutral value and the lateral acceleration or the longitudinal acceleration; and a command for forming the command value corresponding to the difference value. An active suspension device characterized by comprising a value forming means.