JPH0740730A - Active suspension - Google Patents

Abstract

PURPOSE:To reduce a feeling of physical disorder which an occupant feels when a roll of a car body restores in a turning condition in the active suspension. CONSTITUTION:In a reducing condition of the absolute value of a lateral acceleration, a gain KGM=P(n-1)/Y''(n-1) is computed from a pressure instruction value P(n-1) and a lateral acceleration value Y''(n-1) at an instant to convert to the reduction (Steps S50 and S51), and P=KGM.Y''(n) is output as the pressure instruction value to the hydraulic cylinders until the absolute value of the lateral accelerator is made in an increasing condition or to zero (Steps S53, S54, and S47). As a result, since the pressure instruction value P is corrected to feed an energy to a spring at the inner wheel side of the turning, according to the reduction of the lateral acceleration, and the energy accumulated to the outer side wheel of the turning is released according to the reduction of the acceleration, following the roll of the car body, the roll is restored slowly compared in a conventrional system, and the car body can be restored without varying the roll canter.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an active suspension, and more particularly, to an active suspension capable of reducing an uncomfortable feeling felt by an occupant when a roll of a vehicle body is restored during turning.

[0002]

2. Description of the Related Art As an active suspension for controlling a vehicle body roll during turning, a fluid pressure cylinder and a spring interposed between a vehicle body and each wheel, and a working fluid pressure of the fluid pressure cylinder according to a command value. A pressure control valve for controlling the lateral acceleration of the vehicle body, a lateral acceleration detecting or estimating means for obtaining a lateral acceleration of the vehicle body, and a control device for outputting a command value according to the detected value or the estimated value of the lateral acceleration detecting or estimating means. There is something.

In such an active suspension, the lateral acceleration y "(the positive value when turning right) is taken as the horizontal axis,
Fluid cylinder operating pressure p (ie output pressure of pressure control valve)
FIG. 22 shows an example of the control characteristic in which the vertical axis represents. The horizontal axis in this figure corresponds to p = _PN (neutral pressure). In other words, "both predetermined neutral pressure P _N becomes the operating pressure p of the right and left wheels when the = 0, the absolute value of the lateral acceleration | y" | lateral acceleration y in straight running such as a predetermined value a _c
If the operating pressure p is less than or equal to P ₀ (= maximum control pressure P _MAX −P _N ) or −P ₀ , the lateral acceleration | y ″ | increases with turning. Along with this, the operating pressures P on the turning outer wheel side and the inner wheel side both have the same rate of change, the turning outer wheel side increases, the turning inner wheel side decreases, and changes symmetrically between right turn and left turn. Thus, when the absolute value of the lateral acceleration | y ″ | is less than or equal to the predetermined value a _c , so-called roll zero control is performed so that no roll occurs in the vehicle body.

However, in such control characteristics,
The absolute value of the lateral acceleration | y "| exceeds a predetermined value a _c (for example, in FIG. 22 | y" | = a a) and the working pressure p is P
_Since the vehicle body is held at ₀ or −P ₀ , the vehicle body rolls and the spring interposed between the vehicle body and each wheel is deformed in a direction in which the outer wheel side turns and the inner wheel side extends. At that time, the spring on the outer ring side has energy corresponding to the amount of deformation (for example, 0 ≦
| Y "| ≦ a output linearity of extension and the straight line of each wheel in the _c | y" | a = pressure indicated by the intersection between a (eg P _A), P
Energy E _a ] corresponding to the difference from ₀ is accumulated.

From this state, the absolute value of the lateral acceleration | y ″ | decreases as the turning converges, and when the rolled vehicle body returns to its original position, the absolute value of the lateral acceleration | At the time when y ″ | changes from a to a _c , the energy (eg, E _a ) stored on the outer ring side is released.

[0006]

However, if the roll is returned in such a short time that the absolute value of the lateral acceleration | y ″ | changes from a to a _c , the occupant feels uncomfortable when the vehicle body returns to its original position. The present invention has been made by paying attention to the above-mentioned problems of the conventional technique, and when the roll is returned slowly, when the vehicle body rolled at the time of turning returns to the original state. The purpose is to reduce the discomfort felt by passengers.

[0007]

In order to achieve the above object, a first aspect of the present invention is to provide a fluid cylinder interposed between a vehicle body side member and a wheel side member, as shown in FIG. A spring, a control valve that individually controls each fluid cylinder according to a command value, a lateral acceleration detection or estimation unit that detects or estimates the lateral acceleration of the vehicle body, and a lateral acceleration of the lateral acceleration detection or estimation unit. Command value calculation means for calculating the command value given to each control valve for each wheel based on the detected or estimated value, and command value output means for outputting the command value calculated by this command value calculation means to each control valve. In the active suspension, the command value calculation means includes spring deformation correction means for correcting the deformation of the spring by the roll with respect to the command value when the vehicle body roll returns. To provide a scan pension.

According to a second aspect of the present invention, the spring deformation correcting means according to the first aspect releases the energy stored in the outer ring side spring and supplies the energy to the inner ring side spring when the vehicle body is rolled. Provide suspension.
A third aspect of the present invention provides the active suspension, wherein the spring deformation correcting means according to the first or second aspect corrects the deformation of the spring according to the lateral acceleration detected or estimated by the lateral acceleration detecting or estimating means. To do.

According to a fourth aspect of the present invention, the spring deformation correcting means according to the first or second aspect is provided with a stroke detecting means, and the spring deformation correcting means corrects the deformation of the spring according to a detection value of the stroke detecting means. I will provide a.

[0010]

In the active suspension according to the first aspect, when the vehicle body roll is returned, the spring deformation correction means corrects the deformation of the spring caused by the roll. Therefore, the spring deformation correction means is stored in the outer ring spring during turning. Energy is released or the energy is supplied to the inner ring side spring, the energy stored in the outer ring turning spring is supplied or the energy is supplied to the inner ring side spring when the roll returns. The command value thus corrected is calculated for each wheel by the command value calculation means. Then, each command value is output to the control valve by the command value output means. Here, for example, when a pressure control valve is used as the control valve,
As a result, when the roll returns, the working pressure of the fluid cylinder on the outer turning wheel side becomes lower than normal or the working pressure of the fluid cylinder on the inner turning wheel side becomes higher than normal. According to this control, the operating pressure of each fluid cylinder is corrected in the direction of promoting the roll of the vehicle body, and as a result, the roll returns gently. At this time, as in the active suspension according to claim 2, if the correction is such that the energy stored in the spring on the outer turning wheel side is released at the time of rolling, the energy is supplied to the spring on the inner turning wheel side at the same time. The car body can be restored without changing the center.

In correcting the energy of the turning outer wheel and the energy of the inner wheel in this way, in the active suspension according to the third aspect, for example, the control pressure decrease rate of the outer wheel and the increase rate of the inner wheel with respect to the lateral acceleration decrease due to turning convergence are set. By performing the correction, the time until the roll is returned is controlled, and a rapid change in the transient characteristic is suppressed. On the other hand, in the active suspension according to the fourth aspect, if the suspension stroke is detected and is changed in a direction in which the stroke change rate is suppressed at the time of roll return, it is generated in the opposite direction that occurs at the time of return that causes rocking. Roll speed can be reduced, and abrupt changes in vehicle body behavior due to roll convergence can be suppressed.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. The active suspension of each embodiment shows a case where only roll control of the vehicle body is performed. First, a first embodiment of the present invention will be described with reference to FIGS. In FIG. 2, 1
0 is the suspension arm member on the vehicle body side, 11FL
-11RR indicates front left-right rear wheels, and 12 indicates active suspension.

The active suspension 12 is a hydraulic cylinder 18 as a fluid cylinder which is interposed between the vehicle body side member 10 and the wheel side members 14 of the wheels 11FL to 11RR.
FL to 18RR, pressure control valves 20FL to 20RR for individually adjusting the operating pressures of the hydraulic cylinders 18FL to 18RR, a hydraulic pressure source 22 of this hydraulic system, and a hydraulic pressure between the hydraulic pressure source 22 and the pressure control valves 20FL to 20RR. Accumulators 24, 24 for accumulating pressure, which are interposed by the pipes 22a, 22b, and a lateral acceleration sensor 26 for detecting acceleration generated in the lateral direction of the vehicle body.
And a controller 30 that individually controls the output pressures of the pressure control valves 20FL to 20RR based on the detection signal of the lateral acceleration sensor 26. In addition, the hydraulic cylinder 18FL ~
Each of the later-described pressure chambers L of 18RR is connected to an accumulator 34 for absorbing unsprung vibration via a throttle valve 32. Further, a coil spring 36, which has a relatively low spring constant and supports a static load of the vehicle body, is arranged between the upper and lower springs of each of the hydraulic cylinders 18FL to 18RR.

Each of the hydraulic cylinders 18FL to 18RR has a cylinder tube 18a.
A lower pressure chamber L separated by a piston 18c is formed in a. And 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. Further, each of the pressure chambers L is connected to the output ports of the pressure control valves 20FL to 20RR via a 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, Japanese Patent Laid-Open Publication No. Sho. No. 64-74111). Then, by adjusting the command current i (command value) supplied to the exciting coil of the proportional solenoid,
Operation that controls the movement distance of the poppet housed in the valve housing, that is, the position of the spool, and that flows between the hydraulic source 22 and the hydraulic cylinders 18FL to 18RR via the supply port and the output port or the output port and the return port. You can control the oil.

FIG. 3 shows the relationship between the command current i (: i _{FL to} i _RR ) applied to the exciting coil and the control pressure p output from the output port of the pressure control valve 20FL (to 20RR). As shown. That is, when the minimum current value i _MIN taking noise into consideration, the minimum control pressure P _NIM is reached. When the current value i is increased from this state, the control pressure p increases linearly in proportion to the current value i and the maximum current When the value is i _MAX , the maximum control pressure P _MAX corresponding to the set line pressure is obtained.
i _N is the neutral command current and P _N is the neutral control pressure.

On the other hand, a lateral acceleration sensor 26 is fixedly installed on the vehicle body. The lateral acceleration sensor 26 detects lateral (vehicle width) acceleration acting on the vehicle body. For example, the controller controls a voltage signal g corresponding to a displacement amount when a magnetically floated mass is displaced by an inertial force. Output to 30. As shown in FIG. 4, the detection characteristic thereof is that when the lateral acceleration y ″ = 0, the detection signal g = g _N (predetermined neutral lateral G
Detection value), which increases or decreases in proportion to the lateral acceleration y ″ when the vehicle makes a left turn or a right turn from this state.
Here, the lateral acceleration y ″ has a positive value when turning right and a negative value when turning left.

Further, as shown in FIG. 5, the controller 30 further includes an A / D converter 70 for converting the detection signal g corresponding to the input lateral acceleration y ″ into a digital quantity,
A microcomputer 72 for arithmetic processing, D / A converters 73A to 73D for individually converting the digital voltage command values V _{FL to} V _RR output from the microcomputer 72 into analog amounts, and the analog amount Voltage command value V
_It has drive circuits 74A to 74D which make command currents i _{FL to} i _RR individually output to the pressure control valves 20 _{FL to 20 RR} with _{FL to} V _RR as a target value follow the target value.

Among them, the microcomputer 72 includes at least the interface circuit 76 and the arithmetic processing unit 78.
And a storage device 80 including a RAM and a ROM, and the interface circuit 76 includes an I / O port and the like. Further, the arithmetic processing unit 78 reads the detection signal g through the interface circuit 76 and performs arithmetic processing and other processing described later based on the detection signal g. The storage device 80 stores in advance a predetermined program and fixed data necessary for executing the processing of the arithmetic processing device 78, and also stores a processing result of the arithmetic processing device 78.

The microcomputer 72 has
The programs shown in FIGS. 6 and 7 are stored. The coefficient K _G described later in this program has the same set absolute value, but is positive for the left wheel and negative for the right wheel. In the program of FIG. 6, the detection signal g of the lateral acceleration sensor 26 is read in step S1, and the process proceeds to step S2. In step S2, the neutral lateral G detection value g _N is subtracted from the detection signal g read in step S1 to obtain the lateral acceleration detection signal Δg. Next, the process proceeds to step S3, and the lateral acceleration y ″ corresponding to the detection signal Δg is referred to by referring to a storage table stored in the storage device 80 in advance.
To calculate.

Next, in step S4, the pressure command values P _{FL to} P _RR for each wheel are set according to the subroutine shown in FIG. The flag F1 in this program is F1 =
When 1, it means that the lateral acceleration is being reduced due to the turning convergence and the operating pressure correction control is being performed. When F1 = 0, the lateral acceleration is being increased by turning and the operating pressure correction is performed. It means not going. Further, P ₀ = maximum control pressure P _MAX −neutral pressure P _N.

That is, the lateral accelerations y " _(n-1) and y" _(n) of the previous time and this time are read in step S41, and the process proceeds to step S42. Where the previous lateral acceleration y ″
_(n-1) is compared with the current lateral acceleration y ″ _(n) to determine whether the lateral acceleration is increasing or decreasing. Then, the lateral acceleration is increasing (that is, | y ″). _(n) ｜-｜ y ″
_{If (n-1)} | ≧ 0), the process proceeds to step S43 and the flag F1 is set to 0. Then the process proceeds to step S44, the process proceeds to step S45 to calculate the pressure command value P = K _G · y "to _(n).

In step S45, it is determined whether the absolute value | P | of the pressure command value is P ₀ or less, and | P |
If ≦ P ₀ , the process proceeds to step S46 to set this P to the pressure command value, and further proceeds to step S47 to output this P as the pressure command value. In step S45 | P
If |> P ₀ is determined, the process proceeds to step S48 to set P ₀ to the pressure command value, and further proceeds to step S47 to output P ₀ as the pressure command value P.

In step S42, the direction in which the lateral acceleration decreases
(That is, | y ″_(n)｜ − ｜ y ″ _(n-1)| <0)
If it is determined that the step S49 is performed, the process proceeds to step S49.
It is determined whether or not lag F1 = 1, and if F1 ≠ 1,
Moves to step S50 and the previous pressure command value P_(n-1)
Is read, the process proceeds to step S51, and P_(n-1)/ Y ″
_(n-1)To K_GM(Gain) and store this
After storing in 80, the process proceeds to step S52. here
The flag F1 is set to 1, and the process proceeds to step S53 to move the pressure finger.
Order value P = K_GM・ Y ″_(n)And then step S4
Then, the flow shifts to 7 and this P is output as a pressure command value.

When it is determined that the flag F1 = 1 in step S49, the process proceeds to step S54 and the storage device 80
After reading the K _GM stored in step S53 and calculating the pressure command value P = K _GM · y ″ _(n) in step S53,
In step S47, this P is output as a pressure command value. When the pressure command value is output in step S47, the process returns to the main program shown in FIG.

After that, the arithmetic processing unit 78 proceeds to step S5 of FIG. 6 and sets the voltage command values V _{FL to} V _RR (set in step S4) for achieving the pressure command values P _{FL to} P _RR of each wheel. The pressure command values P _{FL to} P _RR and the neutral pressure P _N are added to calculate the actual operating pressure p). Then, in step S6, the voltage command values V _{FL to} V _RR are individually output to the D / A converters 73A to 73D via the interface circuit 76.

Next, the operation of the above embodiment will be described. It should be noted that here, only the control performed by the vehicle traveling straight or turning and the vehicle behavior are considered. When the ignition switch of the vehicle body is turned on, the controller 30 is activated and the timer interrupt process shown in FIG. 6 is executed at predetermined time intervals (for example, 20 msec) during execution of a predetermined main program.

Now, it is assumed that the vehicle body travels straight on a good road having no unevenness at a constant speed. In this state, since lateral acceleration due to turning is not generated, the detection signal g of the lateral acceleration sensor 26 is its neutral value g _N , and the controller 30
The lateral acceleration y ″ calculated by is zero (see steps S1 to S3 in FIG. 6). | Y ″ _(n) | − | y ″
_(n-1) | = 0, so each pressure command value P _{FL to} P _RR = 0
(Operating pressure p = _PN ) (steps S41 to S4 in FIG. 7)
7). Therefore, the voltage command value V _{FL to} V _RR = V
_N (voltage value for setting the operating pressure p of the hydraulic cylinders 18FL to 18RR to P _N ) is calculated (see step S5 in FIG. 6), and this neutral voltage command value V _N is the D / A converter 73A to.
It is output to 73D respectively.

Then, the voltage command values V _{FL to} V _RR (=) converted into analog amounts by the D / A converters 73 A to 73 D.
V _N) are respectively outputted to the drive circuit 74A~74D as a target value, the target value V _N from the driving circuit 74A~74D
The neutral command current i _N corresponding to the pressure control valves 20FL to 20R
It is supplied to R respectively. As a result, the pressure control valve 20FL
The 20RR controls the operating pressure p of the hydraulic cylinders 18FL to 18RR to the neutral pressure P _N (see FIG. 3), so that each of the hydraulic cylinders 18FL to 18RR generates a force corresponding to the neutral pressure P _N to generate the vehicle body. Is held in a neutral posture at a predetermined vehicle height value.

When the constant speed straight traveling state is changed to, for example, a right turning state, an inertial force acts on the right side of the vehicle body to try to generate a roll in which the left side of the vehicle body sinks and the right side floats. At the time of this right turn, the detection signal g of the lateral acceleration sensor 26 is larger than the neutral lateral G detection value g _N by an amount corresponding to the turning speed and the like, so that the controller 30 has a lateral acceleration signal Δg> 0. This Δ in step S3 of FIG.
A positive lateral acceleration y ″ corresponding to g is calculated, and the pressure command values P _{FL to} P _RR for each wheel are set based on the lateral acceleration y ″.

Now, referring to FIG. 8, the pressure command value P on the left wheel side, which is the outer wheel for turning, will be described. When the lateral acceleration y ″ increases from step S41 to steps S42 and S43, the predetermined value a _c (P ₀ = K _G · a _c , maximum control pressure P
_MAX = when P ₀ + P _N) or less, so that the pressure command value P is increased along a straight line L ₁ represented by is and set P = K _G · y In S45～S46 "calculated in step S44 is controlled in. Thus, the hydraulic cylinder 18FL of the left wheel side, the working pressure p in 18RL and higher by the pressure command value P min from the neutral pressure P _N, the roll does not occur in the vehicle body. Thus the straight line L ₁ is Roruzero It is a control curve.

The lateral acceleration y "is determined from steps S41 to S4.
2, the predetermined value a in the increasing state up to S43_cGreater than
If not, go from step S45 to step S48 and go to step S48.
Wait P ₀→ P, and the left wheel that is the outer turning wheel is activated
Pressure p is P_MAXThe lateral acceleration is further increased because the
Rolling occurs in the car body due to the
Energy is applied to the spring (for example, when y ″ = a, E_a)
Is accumulated.

If the lateral acceleration y "decreases from this state through steps S41 to S42 and S49, the previous lateral acceleration y" is determined in steps S50 and S51.
_(n-1) and pressure command value P _(n-1) , P _(n-1) / y "
_(n-1) is calculated as K _GM (gain), and then step S
A straight line L ₃ proportional to the lateral acceleration y ″ (passing the origin, tilting K
_{It is} a straight line of _GM and is on the lower pressure side than the straight lines L ₁ and L ₂ (P = P ₀ ). ), The pressure command value P is controlled so as to decrease, and the operating pressure p of the hydraulic cylinders 18FL, 18RL on the left wheel side is controlled.
Is controlled to a pressure lower than that in the lateral acceleration increasing state.

As a result, the energy E _a stored in the spring interposed between the vehicle body and the left wheel is released while y ″ becomes 0 from a, and the roll slowly returns. As for the pressure command value P on the right wheel side, the predetermined value a _c when the lateral acceleration y ″ is in the increasing state as described above.
The case below, is controlled. Thus, as decreases along the straight line L ₁₁ that pressure command value is expressed as P = K _G · y ", of the right wheel side hydraulic cylinder 18FR, the operating pressure p of the 18RR The neutral pressure P _{N is} reduced by the pressure command value P to prevent the vehicle body from rolling, but the vehicle body rolls when the lateral acceleration y ″ is increased and is larger than the predetermined value a _c .

Then, the lateral acceleration y ″ decreases from this state.
When doing, the previous lateral acceleration y ″ _(n-1)And pressure command value
P_(n-1)And from P_(n-1)/ Y ″_(n-1)To K_GM(gain)
And a straight line L proportional to the lateral acceleration y ″₃₁(origin
Through the slope K_GMStraight line, straight line L₁₁, L_{twenty one}(P = -P
₀) Higher pressure side. ) Pressure to increase along
The command value P is controlled, and the right wheel hydraulic cylinders 18FR, 1
The working pressure p of 8RR is higher than that when the lateral acceleration is increased.
Controlled by force. As a result, there is no interposition between the vehicle body and the right wheel.
The energy is supplied to the spring
Comes back.

Thus, when the roll returns, the energy stored in the spring on the outer ring side is released according to the decrease in the lateral acceleration, and the energy is supplied to the spring on the inner ring side according to the decrease in the lateral acceleration. Since the pressure command value is corrected, the roll returns slowly over a long time compared to the case where the roll is returned while y ″ changes from a to a _c, and the vehicle body is restored without changing the roll center. Therefore, when the roll is returned, the transient abrupt change in the behavior of the vehicle body is suppressed, and the discomfort given to the occupant can be reduced as compared with the conventional case.

In this embodiment, the lateral acceleration sensor 2
6, A / D converter 70, and steps S1 to S of FIG.
The process of 3 constitutes the lateral acceleration detecting means, and the step of FIG.
Steps S4 to 5 correspond to the command value calculating means, and step S in FIG.
6, D / A converters 73A to 73D, drive circuit 74A
.About.74D constitutes command value output means. Also this
In the program, steps S49 to S54 of the present invention are
It corresponds to a spring deformation correction means. Where the lateral acceleration y ″ is
When the lateral acceleration y ″ is a in the decreasing state, _cIf
Also in steps S49-54_GMIs calculated,
At this time K_GM= K_GAnd the straight line L₁Or L₁₁Along
Thus, the pressure command value P is controlled. Ie in this case
Steps S49 to S54 are performed by the spring deformation correcting means of the present invention.
Not applicable, but in this case the above energy to the spring
(For example, E when y ″ = a_a) Is not generated, it is corrected
You don't even have to.

Next, a second embodiment of the present invention will be described. In this embodiment, instead of the program of FIG. 7 in the first embodiment, the program shown in FIG. 9 is stored in the microcomputer 72 as a subroutine of step S4 in FIG. It has the same configuration as the example. The coefficient K _G described later in this program has the same set absolute value, but is positive for the left wheel and negative for the right wheel.

That is, in step S4 of FIG. 6, the following processing is performed based on FIG. The flag F1 in this program means that when F1 = 1, the lateral acceleration is being reduced due to the turning convergence and the operating pressure correction control is being performed. When F1 = 0, the lateral acceleration is increased by turning. It means that the working pressure is not corrected. Also, P ₀ = best control pressure P _MAX - a neutral pressure P _N, b is a predetermined lateral acceleration threshold that satisfies _{0 <b <a c, P} 1 satisfies P ₁ = K _G · b It is a pressure value.

In step S401, the horizontal addition of the previous time and this time is performed.
Speed y ″_(n-1), Y ″_(n)And pressure value P₀And read,
The process moves to step S402. Where the previous lateral acceleration
y ″ _(n-1)And this lateral acceleration y ″_(n)Compare with
Determine whether the acceleration is increasing or decreasing. That
The lateral acceleration increases (that is, | y ″_(n)｜ −
｜ y ″_(n-1)If | ≧ 0), move to step S403.
And sets the flag F1 to 0 and then moves to step S404.
Pressure command value P = K_G・ Y ″_(n)And calculate
Go to step S405.

In step S405, it is determined whether the absolute value | P | of the pressure command value is P ₀ or less, and | P
If | ≦ P ₀ , the process proceeds to step S406 to set P to the pressure command value, and further proceeds to step S407 to output P as the pressure command value. Step S40
If | P |> P ₀ is determined in step 5, step S40
The P ₀ is set to the pressure command value shifts to 8, further proceeds to step S407 and outputs the P ₀ as the pressure command value P.

If it is determined in step S402 that the lateral acceleration is in the decreasing direction (that is, | y " _(n) |-| y" _(n-1) | <0), the process proceeds to step S409. Then, the predetermined lateral acceleration threshold value b and the pressure value P ₁ stored in the storage device 80 are read, and the process proceeds to step S410. In step S410, the absolute value of lateral acceleration | y ″
It is determined whether or not | is less than or equal to b, and if | y ″ | ≦ b, the process proceeds to step S404 and steps S404 to S4 described above are performed.
Execute 07.

If it is determined in step S410 that | y ″ |> b, the process proceeds to step S411 and the flag F1 is set.
= 1 is determined, and if F1 ≠ 1, the process proceeds to step S412, the previous pressure command value P _(n-1) is read, and the process proceeds to step S413 (P ₀ -P ₁ ) /
_Let (y ″ _(n-1) −b) be K _GM (gain) and P ₀ −
[(P ₀ −P ₁ ) / (y ″ _(n−1) −b)] y ″ _(n−1) is calculated as the intercept A and stored in the storage device 80.

Then, the flow shifts to step S414 to set the flag F1 to 1, and further shifts to step S415 to calculate the pressure command value P = K _GM · y ″ _(n) + A, and then shifts to step S407. This P is output as a pressure command value If the flag F1 = 1 is determined in step S411, the process proceeds to step S416 and the storage device 80 is operated.
The _KGM and A stored in is read, and step S
After shifting to 415 to calculate the pressure command value P = K _GM · y ″ _(n) + A, shift to step S407 and output this P as a pressure command value. After outputting, the process returns to the main program shown in FIG.

Next, of the operation of this embodiment, only the control portion when the roll returns (the portion different from the first embodiment) will be described with reference to FIG.
It is shown below based on. As for the left wheel (outer wheel) when turning right, when the roll returns, that is, when the lateral acceleration y ″ that is equal to or greater than _ac decreases, until steps y ″ = b, steps S401 to S402, This state is determined in step S410 through step S409, and step S41
1, and in steps S412 and 413 (P ₀ −P ₁ ).
/ (Y ″ _{(n −1)} −b) as K _GM (gain), P ₀ −
[(P ₀ −P ₁ ) / (y ″ _(n−1) −b)] y ″ _(n−1) is calculated as the intercept A, and steps S 411 to S 41 are performed.
2 to 414 or S416 to pass each of two points (b, P ₁ ) and (a, P ₀ ) at S415 to form a straight line L ₄ (a straight line having an intercept A and a slope K _GM ) proportional to the lateral acceleration y ″. Along with this, the pressure command value P is controlled so as to decrease.

When the lateral acceleration y ″ further decreases and becomes y ″ ≦ b, this state is determined in step S410, the process proceeds to step S404, P = K _G calculated in step S404 and set in steps S405 to 406. The pressure command value P is controlled to decrease along the straight line L ₁ represented by y ″ _(n) , that is, the left wheel side hydraulic cylinder 18FL,
The operating pressure p of 18RL is controlled to a pressure lower than that in the lateral acceleration increasing state when y ″> b, and is controlled to be the same as when the lateral acceleration increasing state is y ″ ≦ b.

As a result, the energy E _a stored in the spring interposed between the vehicle body and the left wheel is released while y ″ changes from a to b, and when y ″ = b, the vehicle body returns to its original state. Return to posture. As for the pressure command value on the right side, which is the inner ring, when the roll is returned, as shown in FIG.
Is changed from a to b, the pressure command value P increases along a straight line L ₄₁ symmetric to the straight line L ₄ across the horizontal axis, and is controlled to return to L ₁ when y ″ ≦ b. The operating pressure p of the hydraulic cylinders 18FR and 18RR on the wheel side is controlled to be higher than that in the lateral acceleration increasing state when y ″> b, and is controlled to be the same as that when the lateral acceleration increasing state is satisfied in y ″ ≦ b. With this, while the energy is being supplied to the spring interposed between the vehicle body and the right wheel, the roll returns slowly until y ″ = b.

Thus, when the roll returns, the energy stored in the spring on the outer ring side is released according to the decrease in lateral acceleration, and the energy is supplied to the spring on the inner ring side according to the decrease in lateral acceleration. Since the pressure command value is corrected, the roll returns slowly over a longer time than in the conventional case, the vehicle body can be returned to its original position without changing the roll center, and the dead zone of y ″ ≦ b By setting to, it is possible to further reduce the uncomfortable feeling given to the occupant.

The relationship between the lateral acceleration y ″ and the amount of energy released is shown in FIG. 1 in comparison with the case of the first embodiment.
Graphs 1 and 12 are shown. In FIG. 11 showing the first embodiment, the amount of energy released is constant until the lateral acceleration becomes 0. Therefore, as shown by the solid line in FIG. In some cases, when the vehicle is accelerated in the reverse roll direction and returns straight, it becomes the initial speed and rollback cannot be avoided. On the other hand, in the second embodiment, as shown in FIG.
Since the constant amount of energy is released before the lateral acceleration becomes 0 (| y ″ | = b), the roll speed becomes 0 before returning to straight running as shown by the broken line in FIG. Therefore, it is hard to cause swinging back.

In this program, step S40
9 to 416 correspond to the spring modification correction means of the present invention. Here, even when the lateral acceleration y ″ is in a decreasing state and the lateral acceleration y ″ is equal to or smaller than a _c , K _GM and A are calculated in steps S409 to 416, but at this time, K _GM =
K _G , A = 0, and the pressure command value P is decreased along the straight line L ₁ from the beginning. That is, steps S409 to 416 in this case do not correspond to the spring deformation correcting means of the present invention, but in this case, the above-mentioned energy (for example, E _a when y ″ = _a ) does not occur in the spring, so it is necessary to correct it. Nor.

A third embodiment of the present invention will be described with reference to FIGS. Although FIG. 14 is a schematic configuration diagram of this embodiment, vehicle height sensors 27a to 27d for each wheel are added to FIG. 2 showing the configurations of the first and second embodiments, and the vehicle height sensors 27a to 27d are added. The detection signals f _{FL to} f _RR from 27d are output to the controller 30a. As for the detection signal f, as shown in FIG. 15, the stroke ST has a predetermined standard value ST _0.
At that time, f = f _N (predetermined standard stroke detection value).

Further, as shown in FIG. 16, the controller 30a has an A / A for the detection signals f _{FL to} f _RR inputted from the vehicle height sensors 27a to 27d in the controller 30 of the first and second embodiments. The D converters 70a to 70d are added. The programs shown in FIGS. 17 and 18 are stored in the microcomputer 72. First, the detection signal g of the lateral acceleration sensor 26 is read in step S1 of the flowchart of FIG. 17, and the process proceeds to step S2. In this step S2, the neutral lateral G detection value g _N is subtracted from the detection signal g read in step S1,
The lateral acceleration detection signal Δg is obtained. Next, in step S3, the lateral acceleration y ″ corresponding to the detection signal Δg is calculated by referring to a storage table stored in the storage device 80 in advance.

Then, the process goes to step S4, the detection signals f _{FL to} f _RR of the vehicle height sensors 27a to 27d are read, and the process goes to step S5. In this step S5, the standard stroke detection value f _N is subtracted from the detection signals f _{FL to} f _{RR of the} vehicle height sensors 27a to 27d to obtain the vehicle height detection signals Δf _{FL to} Δf _RR for each wheel. Next, the process proceeds to step S6, and the strokes ST _{FL to} ST _RR corresponding to the detection signals Δf _{FL to} Δf _RR are calculated by referring to a storage table stored in the storage device 80 in advance.

Next, in step S7, the pressure command values P _{FL to} P _RR for each wheel are set according to the subroutine shown in FIG. The flag F1 in this program is F1
When = 1, it means that the lateral acceleration is decreasing due to the turning convergence and the operating pressure correction control is being performed. When F1 = 0, the lateral acceleration is increasing due to the turning and the operating pressure correction is performed. It means that you have not done.

That is, in step S71, the previous and current lateral accelerations y " _(n-1) , y" _{(n) and the} current stroke ST _(n) are read, and the flow proceeds to step S72.
Here, the previous lateral acceleration y ″ _(n−1) and the current lateral acceleration y ″ _(n) are compared to determine whether the lateral acceleration is increasing or decreasing. If the lateral acceleration is in the decreasing direction (that is, | y ″ _(n) | − | y ″ _(n-1) | <0), the process proceeds to step S73, and it is determined whether the flag F1 = 1. If F1 ≠ 1, the process proceeds to step S74,
Stroke ST _(n) at maximum roll stroke ST _M
Is stored in the storage device 80, and then the process proceeds to step S75 to set the flag F1 = 1.

When the flag F1 = 1 is determined in step S73, the process proceeds to step S76 to read the standard stroke ST ₀ , and the process proceeds to step S77 to ST.
_(n) = ST ₀ is determined. If ST _(n) ≠ ST ₀ , the process proceeds to step S78 and the pressure correction value ΔP = K
(ST _M −ST _(n) ) is calculated and the process proceeds to step S79. Here, K is a predetermined gain. Then, after the normal pressure command value P _r is read in step S79, the process proceeds to step S80, and the pressure command value P = P _r + ΔP is output. Here, the normal pressure command value P _r is set so that the stroke ST changes linearly with respect to the lateral acceleration y ″ as shown in FIG. 19 and increases on the outer wheel side as the lateral acceleration increases. , The inner ring side is controlled so as to decrease, and is calculated by individual processing not described in detail and updated and recorded in the storage device 80.

When ST _(n) = ST ₀ is determined in step S77 and the direction in which the lateral acceleration increases in step S72 (that is, | y ″ _(n) | − | y ″ _(n-1) | ≧ 0 ), It proceeds to step S81 and ΔP =
When 0, F1 = 0, the process proceeds to step S79, the normal pressure command value P _r is read, and then the process proceeds to step S80 to output the pressure command value P = P _r + ΔP. That is, the normal pressure command value P _r is output as the pressure command value P. When the pressure command value P is output in step S80, the pressure shown in FIG.
Return to the main program.

After that, the arithmetic processing unit 78 proceeds to step S8 of FIG. 17 and voltage command values V _{FL to} V _RR (set at step S7) for achieving the pressure command values P _{FL to} P _RR of each wheel. The pressure command values P _{FL to} P _RR and the neutral pressure P _N are added to calculate the actual operating pressure p). Then, in step S9, the voltage command values V _{FL to} V _RR are individually output to the D / A converters 73A to 73D via the interface circuit 76.

Next, the operation of this embodiment will be described. ｜ y ″ _(n) ｜ − |
Since y ″ _(n−1) | ≧ 0, steps S71 to S7
2, through S81 to S79, the normal pressure command value P _r is output as the pressure command value in step S80. At this time, the operating pressure p of the hydraulic cylinder is controlled based on the normal pressure command value P _{r so} that the outer wheel increases and the inner wheel decreases as the lateral acceleration increases, as shown in FIG. Further, as the lateral acceleration increases, the vehicle body rolls, the stroke on the inner wheel side increases, and the stroke on the outer wheel side decreases.

Then, steps S71 to S72, S7
At the time of the roll returning to 3, the moment at which | y ″ _(n) | − | y ″ _(n-1) | <0 in step S74 until the stroke ST _(n) becomes the standard stroke ST _0. Stroke ST _(n) of maximum roll ST
After being stored as _M , this state is determined in step S77 through steps S73 to S76, and steps S78 to S80 are reached, in which the absolute value of the lateral acceleration decreases and the stroke S
The absolute value of the pressure correction value ΔP is controlled to increase as the difference between T _(n) and the standard stroke ST ₀ decreases. When the stroke ST _(n) returns to the standard stroke ST ₀ , this state is determined in step S77, the process proceeds to step S79 via step S81, and the normal pressure command value P _r set here is set to the pressure command in step S80. It is output as the value P.

That is, the pressure correction value ΔP added to the normal pressure command value P _r is controlled as shown in FIG. 20 according to the stroke ST _(n) , and the force for restoring the spring deformation is restored. A force (pressure correction value P) against the (normal pressure command value P _r ) is given. Along with this, the working pressure of the outer wheel side hydraulic cylinder 18 is controlled to be lower than that in the lateral acceleration increasing state, and the working pressure of the inner wheel side hydraulic cylinder 18 is controlled to be higher than that in the lateral acceleration increasing state. It That is, since energy corresponding to the pressure correction value ΔP is released on the outer wheel side and energy corresponding to the pressure correction value ΔP is supplied to the inner wheel side, the roll returns slowly.

As a result, as shown in FIG. 21, the integral value of the vehicle body acceleration in the return direction of the spring, that is, the roll speed of the vehicle body in the opposite direction, is determined at the convergence point of the roll acceleration, that is, from the turning to the straight traveling. Since it can be made 0 or smaller at the time of transition, it is possible to prevent swingback when going straight from turning. Further, since the control is performed on both sides of the outer wheel and the inner wheel, the vehicle body can be returned to the original state without changing the center of the roll. In this way, it is possible to reduce the discomfort felt by the occupant when the roll returns.

In the above embodiment, the lateral acceleration sensor 2
6, A / D converter 70, and steps S1 to S1 of FIG.
The processing of S3 constitutes lateral acceleration detecting means, and the vehicle height sensor 2
7a to 27d, A / D converters 70a to 70d, and the processing of steps S4 to S6 of FIG. 17 constitute stroke detection means, and steps S7 to 8 of FIG. 17 correspond to command value calculation means. Step S9, the D / A converters 73A to 73D, and the drive circuits 74A to 74D form a command value output means. Also, in this program,
Steps S73 to 80 correspond to the spring deformation correction means of the present invention.

As described above, in each of the above-described embodiments, when the vehicle body roll is returned, the pressure command value releases the energy stored in the outer ring side spring at the time of rolling by the spring deformation correcting means, and the inner ring side spring energy is released. Although it is corrected so as to be supplied, the spring deformation correcting means of the present invention may correct only one of the outer ring side and the inner ring side as described above.

The means for determining the lateral acceleration of the present invention is
The invention is not limited to the structure in which the inertial force is directly detected by using the lateral acceleration sensor as described above. For example, a means for estimating the lateral acceleration based on the vehicle speed and the steering angle (for example, see JP-A-62-293167). ) May be sufficient. Also,
The present invention can of course be applied to an active suspension that also performs pitch control and bounce control of the vehicle body.

Further, the fluid cylinder of the present invention is not limited to the case where the hydraulic cylinder is applied as in the above-mentioned embodiment, and for example, a pneumatic cylinder or the like may be used, and the control valve is the fluid cylinder. It is also possible to control the flow rate of.

[0067]

As described above, in the active suspension according to the first aspect, when the vehicle body roll is returned, the spring deformation correction means corrects the deformation of the spring caused by the roll. If the energy stored in the outer wheel springs is released during turning, or if the energy is supplied to the inner ring springs, the roll return will be slower and the occupant will be restored when the vehicle body roll that occurs during turning is restored. It is possible to reduce the discomfort given to the.

According to the active suspension of the second aspect, in order to perform the correction so that the energy stored in the spring on the outer wheel side of the turning is released at the same time as the correction, the energy is supplied to the spring on the inner wheel side of the turning. Since the vehicle body can be returned without changing the center of the roll, the rolled vehicle body can further reduce the uncomfortable feeling given to the occupants when the vehicle body is returned to its original state.

According to the active suspension of the third aspect, in correcting the energy of the turning outer wheel and the energy of the inner wheel, for example, the control pressure decrease rate of the outer wheel and the increase rate of the inner wheel with respect to the decrease in lateral acceleration due to turning convergence are corrected. By doing so, the return of the roll becomes gradual, and the sense of discomfort given to the occupant when the roll of the vehicle body is restored during turning can be reduced.

According to the active suspension of the fourth aspect, in correcting the energy of the turning outer wheel and the energy of the inner wheel, if the suspension stroke is detected and is changed in the direction of suppressing the stroke change rate when the roll returns. Therefore, it becomes difficult for the roll to swing back when the roll is returned, and the sense of discomfort given to the occupant when the roll of the vehicle body is restored when turning is reduced.

[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 first and second embodiments of the present invention.

FIG. 3 is a graph showing an output characteristic of a pressure control valve.

FIG. 4 is a graph showing a detection characteristic of a lateral acceleration sensor.

5 is a block diagram showing an example of the controller of FIG. 4. FIG.

FIG. 6 is a flowchart showing an example of a processing procedure executed in a controller regarding the first and second embodiments.

FIG. 7 is a flowchart of a subroutine corresponding to step S4 of the flowchart of FIG. 6 regarding the first embodiment.

FIG. 8 is a control characteristic diagram of a pressure command value in the first embodiment.

FIG. 9 is a flowchart of a subroutine corresponding to step S4 of the flowchart of FIG. 6 regarding the second embodiment.

FIG. 10 is a control characteristic diagram of a pressure command value in the first embodiment.

FIG. 11 is a graph showing the relationship between the lateral acceleration y ″ and the amount of energy released when the roll returns in the first embodiment.

FIG. 12 is a graph showing the relationship between the lateral acceleration y ″ and the amount of energy released when the roll returns in the second embodiment.

FIG. 13 is a graph showing the relationship between roll acceleration and roll speed when the roll returns, for the first and second examples.

FIG. 14 is a schematic configuration diagram showing a third embodiment of the present invention.

FIG. 15 is a graph showing a detection characteristic of a vehicle height sensor sensor.

16 is a block diagram showing an example of the controller of FIG.

FIG. 17 is a flowchart illustrating an example of a processing procedure executed by a controller according to the third embodiment.

FIG. 18 is a schematic flowchart of a subroutine corresponding to step S7 in the flowchart of FIG. 17, regarding the third embodiment.

FIG. 19 is a graph showing the relationship between lateral acceleration y ″ and stroke ST in the third embodiment.

FIG. 20 is a graph showing the relationship between the pressure correction value ΔP and “stroke ST _(n) -standard stroke ST ₀ ” in the third embodiment.

FIG. 21 is a graph showing the relationship between roll acceleration and roll speed when the roll returns, in the third example.

FIG. 22 is a conventional control characteristic diagram of operating pressure.

[Explanation of symbols]

 10 Body side member 12 Active suspension 14 Body side member 18FL-18RR Front left-rear right hydraulic cylinder (fluid cylinder) 20FL-20RR Front left-rear right pressure control valve 26 Lateral acceleration sensor (lateral acceleration detection means) 27a-27d Vehicle height sensor (stroke detection means) 36 Coil spring (spring) 70 A / D converter (lateral acceleration detection means) 70a to 70d A / D converter (stroke detection means) 73A to 73D A / D converter (command value) Output means) 74A to 74D drive circuit (command value output means)

Claims (4)

[Claims] 1. A fluid cylinder and a spring, which are interposed between a vehicle body side member and a wheel side member for each wheel, a control valve for individually controlling each fluid cylinder according to a command value, and a lateral side of the vehicle body. Lateral acceleration detection or estimation means for detecting or estimating directional acceleration, and command value calculation for calculating a command value given to each control valve for each wheel based on the lateral acceleration detection or estimation value of the lateral acceleration detection or estimation means In the active suspension, including means and command value output means for outputting the command value calculated by the command value calculation means to the control valve, the command value calculation means is configured to use the roll when the vehicle body rolls back. An active suspension characterized by having a spring deformation correction means for correcting the amount of spring deformation with respect to the command value. 2. The active member according to claim 1, wherein the spring deformation correcting means releases energy stored in a spring on a turning outer wheel side and supplies energy to a spring on a turning inner wheel side when the vehicle body is rolled. Type suspension. 3. The active type according to claim 1, wherein the spring deformation correcting means corrects the deformation of the spring according to the lateral acceleration detected or estimated by the lateral acceleration detecting or estimating means. suspension. 4. The active suspension according to claim 1, wherein the spring deformation correction means includes a stroke detection means, and corrects the deformation of the spring according to a detection value of the stroke detection means. .