JPH0415116A - Active suspension for vehicle - Google Patents

Abstract

PURPOSE:To avoid cost increase and the complexity of a structure or the like, by correcting a feedback control quantity which is based on a variation between actual fluid pressure within an actuator and a corresponding target value, by means of the 1st correction quantity based on a sideway acceleration and the 2nd correction quantity corresponding to a carbody roll angle speed. CONSTITUTION:An electric type controller 62 includes a micro computer 64, and an input port device 72 is inputted with signals from a sideway acceleration sensor 78 and a front and rear acceleration sensor 80, a car height sensor 52 and a pressure sensor 56. And signals thus inputted are outputted to a control valve 26 from an output port device 74 via drive circuits 82-88, according to the instruction of a CPU 66 based on the program of an ROM 68. In this instance, the quantity of control is corrected according to the 1st correction quantity based on a sideway acceleration and the 2nd correction quantity based on the integral value of a variation from the target pressure of fluid pressure within an actuator.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a suspension for a vehicle such as an automobile, and more particularly to an active suspension system.

[Prior Art] As one of the active suspension systems of vehicles such as automobiles, there is a fluid pressure actuator disposed between each wheel and the vehicle body, and a pressure adjustment means for adjusting the fluid pressure in the actuator. A pressure detection means for detecting the fluid pressure in the actuator, a lateral acceleration detection means for detecting the lateral acceleration of the vehicle body, and a deviation between the fluid pressure in the actuator detected by the pressure detection means and the corresponding target value. and control means for controlling the fluid pressure in the actuator to substantially a corresponding target value by feedback controlling the pressure regulating means with a control amount based on the control amount, the control means being detected by the lateral acceleration detecting means. An active suspension system configured to correct a feedback control amount using a correction amount based on lateral acceleration is already known.

In this case, since the value detected by the lateral acceleration detection means includes a roll angular acceleration component of the vehicle body, it is not possible to effectively and appropriately control the roll of the vehicle body.

Now, if the weight of the front or rear wheels of the vehicle is 2W, and the lateral acceleration of the vehicle body caused by turning the vehicle is Gx, then the target support load Fi for the inner turning wheels and the outer turning wheels to avoid the occurrence of body roll is F.

are respectively Fi =W (1-GX) -=-=formula IFo =W
(1+Gx) -------Formula 2. Since the lateral acceleration GX is detected by the lateral acceleration detection means fixed to the vehicle body, if the roll angle of the vehicle body is θ and the distance between the roll center of the vehicle and the lateral acceleration detection means is h, then the lateral acceleration detection means The value Gxa actually detected is Gxa=Gx - hθ, and includes the roll angular acceleration component hθ of the vehicle body.

Therefore, when controlling using the logic of equations 1 and 2,
Hunting of the roll displacement of the vehicle body occurs due to the roll increasing effect due to the roll angular acceleration component. Therefore, instead of the above-mentioned equations 1 and 2, it is necessary to set Ka as a constant less than 1 and control according to the following equations.

Fia-W (1-Ka -GX) Foa-W (1+ Ka -GX) Therefore, the supporting load becomes excessive on the inner turning ring, and conversely, the supporting load becomes excessive on the outer turning ring. ΔFo
-Fo -Foa -W (1-Ka) GX Because the support load is insufficient and it is not possible to effectively and appropriately control the support load of each wheel in response to the load movement during turning,
Rolling of the vehicle body occurs due to a difference in the support loads of the left and right wheels. This problem is particularly noticeable during transient turns, where vehicle body roll cannot be effectively controlled by vehicle height feedback control.

In order to deal with this problem, for example, Japanese Patent Application Laid-Open No. 6270766
As described in the above publication, it has already been proposed to correct the value detected by the lateral acceleration detection means using the roll angular acceleration detected by the two vertical acceleration detection means.

[Problem to be solved by the invention] However, when correction is performed as in the device described in the above-mentioned Japanese Unexamined Patent Publication No. 62-70766, two acceleration detection means are required in addition to the lateral acceleration detection means. Since this is necessary, it is inevitable that the cost will increase, the structure of the active suspension will become more complicated, and the causes of failure will increase.

The present invention requires a means for detecting the roll angular acceleration of the vehicle body in view of the above-mentioned problems in conventional active suspensions in which the feedback control amount of the fluid pressure in each actuator is corrected and controlled based on the lateral acceleration of the vehicle body. It is an object of the present invention to provide an active suspension that is improved so as to be able to effectively and appropriately suppress vehicle body roll, especially transient roll.

[Means for Solving the Problems] According to the present invention, the above object is to provide a fluid pressure actuator disposed between each wheel and a vehicle body, and a pressure adjustment means for adjusting the fluid pressure in the actuator. a pressure detection means for detecting fluid pressure within the actuator; a lateral acceleration detection means for detecting lateral acceleration of the vehicle body; and a target value corresponding to the fluid pressure within the actuator detected by the pressure detection means. control means for substantially controlling the fluid pressure in the actuator to the corresponding target value by controlling the pressure adjusting means with a control amount based on a deviation between A first correction amount based on the lateral acceleration detected by the acceleration detection means, and a second correction amount based on the integral value of the deviation of the fluid pressure in the actuator from the target pressure detected by the pressure detection means. This is achieved by an active suspension for a vehicle configured to correct the control amount.

[Operation of the Invention] When the vehicle turns, assuming that transient support load deviations ΔFI and ΔFo occur in the inner turning wheel and the outer turning wheel, respectively, the roll moment M of the vehicle body is calculated as M−L (with the distance between the left and right wheels being 2L). ΔF1+ΔFo). The moment of inertia of the vehicle body around the roll axis is I
If R, then IR・θ−M, so θ−M/IR −(L/IR)−(ΔFi +ΔFo)...Equation 3 When Equation 3 is integrated by one point, θ(1) is Since it is the roll angular velocity, the transient roll of the vehicle body is proportional to the sum of the integral values of the deviations of the support loads of the left and right wheels from the target support loads.

Here, let F be the force generated by the actuator, W be the supporting load of the corresponding wheel, and let PSA be the fluid pressure in the actuator and the cross-sectional area of the piston, respectively.
There is a relationship F-W-P-A between these, and F and P can be treated as equivalent values except for the size of the value. Therefore, ΔPi and ΔPo are the deviations of the fluid pressures in the actuators of the inner and outer wheels, respectively, from the target pressure, and Kr is a constant). The control means substantially controls the fluid pressure in the actuator to the target value by controlling the pressure adjustment means with a feedback control amount based on the deviation between the target value and the lateral acceleration detected by the lateral acceleration detection means. and a second correction amount based on the integral value of the deviation of the fluid pressure in the actuator from the target pressure detected by the pressure detection means to correct the feedback control amount. .

Therefore, the feedback control amount is corrected not only by the first correction amount based on the lateral acceleration but also by the second correction amount corresponding to the roll angular velocity of the vehicle body, so even if the roll angular acceleration of the vehicle body is not detected, the vehicle body roll In particular, transient rolls are effectively and appropriately suppressed.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention will be explained in detail below by way of example embodiments with reference to the accompanying figures.

Embodiment FIG. 1 is a schematic diagram showing a fluid circuit of one embodiment of an active suspension for a vehicle according to the present invention.

In FIG. 1, 10 indicates a reservoir that stores oil as a working fluid. A connection passage 14 having a filter 12 connected thereto is connected to the reservoir 10, and a working fluid discharge passage 18 having an oil cooler 16 therebetween is connected to the reservoir 10.
is connected at one end. The other end of the connecting passage 14 is connected to the suction side of a pump 22 driven by an engine 20.

One end of a working fluid supply passage 24 is connected to the discharge side of the pump 22 . The other end of the working fluid supply passage 24 and the other end of the working fluid discharge passage 18 are connected to the P port and the R port of the control valve 26, respectively. Although not shown in the drawings, the pump 22 incorporates a relief valve, which is known per se.

In the illustrated embodiment, the control valve 26 is a three-port, three-position switching type solenoid control valve, and its A port is connected to a working fluid chamber 32 of an actuator 30 provided corresponding to each wheel by a connecting passage 28. , is connected to. By controlling the control current supplied to the solenoid 34, the control valve 26 moves from a position 26a where communication between all ports is cut off to a switching position 26b or R port where communication is connected between the P port and the A port. The current value of the control current is switched to the switching position 26C that communicates with the A port, and the current value of the control current is switched to the switching position 26B.
The communication cross-sectional area at the switching position 26C increases, and conversely, as the current value of the control current increases in the negative direction, the communication cross-sectional area at the switching position 26C increases.

In the illustrated embodiment, each actuator 30 is connected to the vehicle body 3.
6 and a piston 44 connected to a suspension arm 42 carrying a wheel 40, which cylinder and piston cooperate with each other to define a working fluid chamber 32. A gas spring 48 is connected to the working fluid chamber 32 through a connecting passage 46, and a throttle 50 is provided in the middle of the passage 46. A vehicle height sensor 52 is provided between the cylinder 38 and the suspension arm 42 to detect the vehicle height of the corresponding portion. The actuator 30 may be connected to the suspension arm 42 on the cylinder 38 side and pivotally supported on the vehicle body 36 on the piston 44 side.

An accumulator 54 is connected to the working fluid supply passage 24, and a pressure sensor 56 is connected to the connection passage 28. Further, an on-off valve 58 is provided in the middle of the connection passage 28. The on-off valve 58 takes in the pressure Ps in the working fluid supply passage 24 as a pilot pressure, and when the pilot pressure is below a predetermined value, the valve is maintained in a closed state to cut off communication with the connection passage 28.

Although omitted in FIG. 1, the control valve 26, the on-off valve 58, the gas spring 48, the throttle 50, and the actuator 30
．． A vehicle height sensor 52, a pressure sensor 56, etc. are provided corresponding to each wheel of the vehicle, and control valves, vehicle height sensors, and pressure sensors corresponding to the right front wheel, left front wheel, right rear wheel, and left rear wheel are provided in the vehicle height sensor 52, pressure sensor 56, etc. In FIG. 2, they are indicated by the symbols fr%f1, r'', and rl, respectively.

The control valve 26 is controlled by an electrical control device 62 shown in FIG. Electrical control device 62 includes a microcomputer 64 . The microcomputer 64 may have a general configuration as shown in FIG.
, a read-only memory (ROM) 68 , a random access memory (RAM) 70 , an input port device 72 , and an output port device 74 , which are connected to each other by a bidirectional common bus 76 .

The input port device 72 receives signals indicating the lateral acceleration GX and longitudinal acceleration cy of the vehicle body, respectively, from a lateral acceleration sensor 78 and a longitudinal acceleration sensor 80 provided at the center of the vehicle body (not shown), and a vehicle height sensor 52fr, 52
Vehicle height Hfr, Hf of the parts corresponding to the right front wheel, left front wheel, right rear wheel, and left rear wheel from f'l, 52rr, and 52rl, respectively.
Signals indicating l, I(rr, Hrl) are input, and the pressure PrrSPfl in the working fluid chamber of the actuator corresponding to the front right wheel, front left wheel, rear right wheel, and rear left wheel is input from the pressure sensors 56fr, 56fl, 56rr, and 56rl, respectively. , Pr
Signals indicating r and Prl are manually input.

The lateral acceleration sensor 78 and the longitudinal acceleration sensor 80 are configured to detect lateral acceleration and longitudinal acceleration with the left side and the front of the vehicle as positive, respectively.

The input port device 72 appropriately processes the signals input thereto and inputs them into the program stored in the ROM 68.
According to instructions from the CPU 66, processed signals are output to the CPU and RAM 70. ROM6
8 stores the control flow shown in FIG. The output port device 74 outputs the drive circuit 8 according to instructions from the CPU 66.
2 to 88 and control valves 26f', 26r1.2, respectively.
A control signal is output to 6rr and 26"1.

The operation of the illustrated embodiment will now be described with reference to the flowchart shown in FIG. The control according to the flowchart of FIG. 3 is started by opening an ignition switch, which is not shown in the figure.

In the first step 10, signals from each sensor shown in FIG. 2 are read, and then the process proceeds to step 20.

In step 20, vehicle height sensors 52rr and 52fl
, 52rr, and 52rl, respectively.
Actual vehicle height H of the parts corresponding to the left front wheel, right rear wheel, and left rear wheel
Target vehicle height Ha corresponding to rr, H "l, Hrr, Hrl
The deviation ΔHi (i=rr, N, r', rl) between "r, Haft Harr, and Harl" is calculated according to the following formula, and then the process proceeds to step 30.

ΔH1-Hat-Hj In step 30, the vehicle height deviation Δ is determined according to the following formula.
The integral value 11 of Hi is calculated, and then the process proceeds to step 40.

If(n)-ΔH1(n)+T-11(n-1) In the above formula, If(n) and I1(n-1) are the current and one cycle previous If, respectively, and T is a time constant.

In step 40, a first target pressure Pli in the working fluid chamber for suppressing changes in the attitude of the vehicle body due to turning and acceleration/deceleration of the vehicle is calculated according to the following formula, and then the process proceeds to step 50. .

Plrr = Pofr + 1x-Gx-Kly-Gy
pH'l-Porl-Klx-GX-1y,
ayPlrr -Porr +KIx-GX +Kly
φayPlrl −Porl − to 1x−Gx +Kl
y-Gy Pof'r, Pof' in each of the above formulas
l Porr and Porl are target values, which are equal to the pressure in the working fluid chamber of the corresponding actuator when the vehicle is stopped on a horizontal road surface.

In step 50, a second target pressure P2i in the working fluid chamber is set to suppress transient roll and pitch of the vehicle body.
is calculated according to the following, and then the process proceeds to step 60.

P2fr - Pofr + to 2X-GX- to 2y-Gy
P2fl - Pofl - to 2x-Gx- to 2y-cy
P2rr - Porr + to 2x-Gx + to 2y-G
>P2rl - Porl - to 2x- Gx + to 2y-
In Gy step 60, the deviation ΔP2i between the second target pressure P2i calculated in step 50 and the corresponding actual pressure P1 in the working fluid chamber is calculated according to the following formula, and then the step・Proceed to Room 70.

ΔP H−P 2j −P i In step 70, bypass filter processing is performed on the signal indicating the pressure deviation ΔP2i calculated in step 60 according to the following formula, so that the pressure after bypass filter processing is The deviation P2hi is calculated, and the process then proceeds to step 80.

P 2hi −ΔP2hj −TI S/ (1+
TI S) where T is a time constant and S is a Laplace operator.

In step 80, a pseudo-integral value P2hli of the pressure deviation is calculated by performing low-pass filter processing on the signal indicating the pressure deviation P2hi after the bypass filter processing according to the following formula, and then in step 9
Go to 0.

P2hli-P2hi / (1+T2 S) T here
2 is a time constant and S is a Laplace operator.

In step 90, the control pressure Pcl for the pressure in the working fluid chamber of each actuator is calculated according to the following equation, and then the process proceeds to step 100.

Pc1−Pti−Pi +Khp・ΔHt +KhisuIi+Kpi−P2hlj In step 100, each control valve 26fr, 26r1.
The control current E1 supplied to the solenoids 26rr and 26rr is calculated according to the following formula, and then step 1
Proceed to step 10.

Ei −Ki −Pcj (Kl is a constant) In step 110, the control current calculated in step 100 is supplied to the solenoid of each control valve, thereby controlling the control pressure Pcj calculated in step 90. The pressure in the working fluid chamber of each actuator is increased or decreased by an amount corresponding to .

Thus, according to the illustrated embodiment, the calculation equation Pli-Pi in step 90 determines the fee (back) based on the deviation between the actual pressure Pi in the working fluid chamber of each actuator and the corresponding target value Poi. Control amount (Poi-
Pi) can be found. Also, a first correction jt (P li
-P oi), a second correction amount (K pi-P 2hli) based on the integral value of the deviation of the actual pressure Pi in the working fluid chamber of each actuator from the target pressure P2i, and a feedback control amount of the vehicle height. The third correction based on ff1(K
hp·ΔHi+Khi·1i), the feedback control amount (Poi−Pi) is corrected.

Assuming that the turning of the vehicle causes lateral acceleration Gx in the pattern shown in Fig. 4, for example,
A change in the pressure Pfr in the working fluid chamber of the actuator for the right front wheel will be explained with reference to the drawings.

Furthermore, the pressure in the working fluid chamber of the actuator of the right rear wheel Prr
The change in pressure Prr is substantially the same as the change in pressure Prr, and the pressure P in the working fluid chamber of the actuator for the left front wheel and the left rear wheel
The changes in fl and Prl are substantially the same as the changes in pressure Pfr, except that they are upside down when viewed in FIG.

In order to suppress the change in attitude of the vehicle body, that is, the occurrence of roll when lateral acceleration GX occurs in the pattern shown in FIG. 4, the pressure Prr in the working fluid chamber of the right front wheel actuator must be It must change as shown by the solid line in FIG.

When the feedback control amount (Pofr -Prr) is corrected only by the correction amount (Plrr -Pofr) based on the detected lateral acceleration GX and longitudinal acceleration Gy, the pressure Prr is indicated by the broken line in Fig. 5. It changes as shown, and the feedback system aii (Po['r −
P Cr) is the correction m (Plfr − Porr ) based on the lateral acceleration Gx and the longitudinal acceleration Gy, and the correction amount (K hp・ΔHfr+
Khf'r I fr), the pressure Pfr changes as shown by the imaginary line in FIG. It is not possible to achieve the required pressure change, and the occurrence of body roll, especially transient roll between times t1 and t2, is unavoidable.

On the other hand, according to the above embodiment, the second correction amount (K pi - P 2hli) corresponds to the roll angular velocity of the vehicle body as described above, and as seen in FIG. The lack of control between the solid line and the virtual line is compensated for by the second correction amount, so that the pressure Prr is substantially reduced to the fifth
Since the control is performed as shown by the solid line in the figure, the roll of the vehicle body, especially the transient roll between times t1 and t2, is reliably prevented from occurring.

Further, according to the illustrated embodiment, bypass filter processing is performed on the signal indicating the pressure deviation ΔP2i in step 70, so that feedback of the hatch jig applied in FIG. 5, that is, the vehicle height is Since it is avoided that the pseudo-integral calculation in step 80 is performed in a manner in which the control amount is included, the cumulative value of the vehicle height feedback control amount is included in the second correction amount. definitely avoided.

Further, according to the illustrated embodiment, the feedback control amount (Pofr −
P fr) is corrected by the second correction amount, so the pitch of the vehicle body, especially the transient pitch, is effectively suppressed.

Although the present invention has been described in detail with respect to specific embodiments, the present invention is not limited to the above-described embodiments, and may be modified to include various other embodiments within the scope of the present invention. It will be clear to those skilled in the art that

[Effects of the Invention] As is clear from the above description, according to the present invention, the feedback control amount is based on the deviation between the actual fluid pressure in the actuator and the corresponding target value, or the feedback control amount is based on the lateral acceleration. Since it is corrected not only by the first correction amount but also by the second correction amount corresponding to the roll angular velocity of the vehicle body, transient roll can be effectively and appropriately suppressed without detecting the roll angular acceleration of the vehicle body. Also, since there is no need to provide two vertical acceleration detection means in addition to the lateral acceleration detection means,
It is possible to avoid an increase in cost, a complicated structure of the active suspension, and an increase in the causes of failure.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing a fluid circuit of one embodiment of an active suspension for a vehicle according to the present invention, FIG. 2 is a block diagram showing an electric control device of the embodiment shown in FIG. 1, and FIG. 3 is a flowchart showing the control flow achieved by the electric control device shown in FIG. 2; FIG. 4 is a graph showing changes in lateral acceleration when the vehicle turns;
FIG. 5 is a graph showing changes in pressure within the working fluid chamber of the actuator for the right front wheel. 10... Reservoir, 12... Filter, 14...
Connection passage, 16... Oil cooler, 18... Working fluid discharge passage, 20... Engine, 22... Pump 1
24... Working fluid supply passage, 26... Control valve, 28
...Connecting passage. 30...Actuator, 32...Working fluid chamber, 3
4... Solenoid, 36... Vehicle body, 38-... Cylinder, 40... Wheel, 42... Suspension arm, 44... Piston, 46... Connection passage, 48...
... Gas spring, 50 ... Throttle, 52 ... Vehicle height sensor, 54 ... Accumulator, 56 ... Pressure sensor, 58 ... Opening/closing valve, 62 ... Electric control device, 64
...Microcomputer. 66...CPU 68...ROM, 70...R
AM, 72... Input port device, 74... Output boat device, 76... Common bus, 78... Lateral acceleration sensor, 80... Longitudinal acceleration sensor, 82-88...
At the time of the drive circuit Applicant: Toyota Motor Corporation Representative Patent Attorney: Masatake Akashi Figure 7. 62 Ki Ni control device

Claims (1)

[Claims] A fluid pressure actuator disposed between each wheel and the vehicle body, a pressure adjusting means for adjusting fluid pressure within the actuator, a pressure detecting means for detecting the fluid pressure within the actuator, and a lateral acceleration of the vehicle body. the actuator by controlling the pressure adjusting means with a control amount based on a deviation between the fluid pressure in the actuator detected by the pressure detecting means and the corresponding target value; a control means for controlling the fluid pressure within substantially the corresponding target value, the control means having a first correction amount based on the lateral acceleration detected by the lateral acceleration detection means; The active suspension for a vehicle is configured to correct the control amount by a second correction amount based on an integral value of a deviation of fluid pressure in the actuator from a target pressure detected by the means.