JPH0492702A - Suspension device for vehicle - Google Patents

Abstract

PURPOSE:To perform properly continuous control of orientation by performing control of orientation by other control mode through prohibition of control of orientation by a control mode, by means of which an inverted roll making control of a car body unstable is effected, when a deviation occurs to a detecting steering angle. CONSTITUTION:The feed and discharge of working liquid to and from a liquid chamber partitioned by the piston of a cylinder device l located to each wheel are controlled by a flow rate control valve 15 for a feed and a flow rate control valve 19 for discharge to regulate a car height, and valves 15 and 19 are controlled by a control unit U. Regarding this device, in a control unit U, a plurality of control modes containing a control mode to perform an inverted roll are set, and a control mode is selected from the control modes based on lateral acceleration detected by a lateral G sensor 63. It is detected that a deviation occurs to steering angles selected by steering angle sensors 96 and 97. During detection of a deviation, a control mode except the control mode to perform an inverted roll is selected as a control mode from a plurality of control modes.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a suspension device for a vehicle.

(Prior art) Vehicle suspensions, generally called passive suspensions, have a damper unit consisting of a hydraulic shock absorber and a spring (generally a coil spring), and the suspension characteristics are determined by the preset characteristics of the damper unit. Set uniformly. Of course, it is also possible to make the damping force of the hydraulic shock absorber variable, but this does not change the suspension characteristics.

On the other hand, recently, so-called active suspensions have been proposed in which the suspension characteristics can be changed arbitrarily. A cylinder device is installed, and the suspension characteristics are changed by controlling the supply and discharge of hydraulic fluid to the cylinder device (see Japanese Patent Laid-Open No. 130418/1983).

In the second active suspension, suspension characteristics can be greatly changed for various posture controls such as vehicle height control, roll control, and pitch control by supplying and discharging hydraulic fluid from the outside.

(Problems to be Solved by the Invention) In the above-mentioned active control, that is, attitude control, the behavior of the vehicle body varies considerably depending on how the control conditions are set. For this reason, instead of setting control conditions uniformly, it has been considered to change control conditions based on parameters governing the running conditions of the vehicle, particularly lateral acceleration (lateral acceleration). That is, it is considered that a plurality of control modes with control conditions are set in advance, and the control mode used for attitude control is selected from among the plurality of control modes based on lateral G. It is also being considered to include a control mode for performing a reverse roll among the plurality of control modes.

When changing the above control mode based on lateral G, it is necessary to detect the lateral G acting on the vehicle body, but since the -S type lateral G sensor is quite sensitive, control using the lateral G sensor is necessary. When the mode is changed, a situation where the control mode is frequently changed is likely to occur (hunting occurs).

From this point of view, it has been considered to theoretically determine the lateral G based on the steering angle and vehicle speed, and to change the control mode based on the theoretically determined lateral G.

However, the steering angle sensor that detects the steering wheel angle is
A situation in which the detected steering angle deviates from the normal steering angle is likely to occur, and the problem is how to deal with this problem.

The present invention was made in consideration of the above circumstances, and
Lateral G theoretically obtained based on steering angle and vehicle speed
An object of the present invention is to provide a suspension system for a vehicle that can perform appropriate attitude control even when a deviation occurs in the detected steering angle, assuming that the control mode is changed based on the following.

(Structure, operation, and effect of the invention) In order to achieve the above object, the present invention has the following structure. That is, a cylinder device is installed between the vehicle body and each wheel and adjusts the vehicle height according to the supply of working fluid, and the supply of working fluid to the cylinder device is based on a predetermined control mode in which control conditions are set. attitude control means for controlling the attitude of the vehicle body by controlling the steering wheel; steering angle detection means for detecting a steering angle; vehicle speed detection means for detecting vehicle speed; and a steering angle detected by the steering angle detection means. A plurality of control modes are set in advance, including a lateral acceleration determining means for determining a lateral acceleration acting on the vehicle body from the vehicle speed detected by the vehicle speed detecting means, and a control mode for performing a reverse roll as the control mode. basic control mode selection means for selecting a control mode to be used by the attitude control means from among the control modes based on the lateral acceleration detected by the lateral acceleration detection means; a deviation detection means for detecting the occurrence of a deviation; and when the deviation detection means detects that a deviation has occurred in the detected steering angle, the attitude control means is used in place of the basic control mode selection means. Temporary control mode selection means for selecting a control mode other than a control mode for performing a reverse roll from among the plurality of control modes as a control mode.

As described above, in the present invention, the control mode is basically changed based on the lateral acceleration theoretically obtained based on the steering wheel angle and the vehicle speed, so the control mode cannot be changed frequently. It is possible to perform posture control in an optimal control mode that suits the vehicle's driving conditions while preventing the vehicle from moving.

In addition, when a deviation occurs in the detected steering angle, attitude control using a control mode that performs reverse roll, which is likely to cause instability in vehicle body control, is prohibited, and attitude control is performed using a control mode other than reverse roll. Even when a deviation occurs in the detected steering angle, attitude control can be appropriately continued.

Control mode selected when a deviation occurs in the detected steering angle (
(This is a control mode other than the control mode that performs reverse roll)
Although it is possible to select only one control mode, for example, select only the control mode that best ensures the stability of the vehicle body, it is preferable to change the control mode using various parameters. It is preferable to do so.

In this case, for example, using vehicle speed as a parameter, when the vehicle speed is high, a control mode that emphasizes stability is selected, and when the vehicle speed is low, a control mode that balances maneuverability and stability is selected. good.

Alternatively, a pseudo lateral acceleration may be obtained based on the steering angle speed and vehicle speed obtained by differentiating the detected steering angle, and the control mode may be changed based on this pseudo lateral acceleration. When using this pseudo lateral acceleration, the vehicle speed is also used as a parameter for changing the control mode, and when the vehicle speed is higher than a predetermined vehicle speed, the control mode is set to emphasize stability, and when the vehicle speed is lower than the predetermined vehicle speed, the control mode is set to emphasize stability. Alternatively, the control mode may be changed based on the pseudo lateral acceleration.

In order to correct or correct the deviation of the detected steering angle, a neutral position detection means for detecting that the steering wheel is in the neutral position, for example, a neutral position detection means that is turned ON depending on whether the steering wheel is in the neutral position or not.
, a limit switch that is turned off is provided, and when the limit switch detects that the steering wheel is in the neutral position, the detected value is set so that it corresponds to the detected value of the steering angle detection means or the neutral position. It is best to correct it.

Detection of a deviation in the detected rudder angle can be easily determined by, for example, providing a first rudder angle detection means and a second rudder angle detection means, and checking whether the detected values of the side angle detection means are different or coincide. I can do it.

(Example) Examples of the present invention will be described below based on the attached drawings. In addition, the code rFJ used with numbers in the following explanation is for the front wheel, rRJ is for the rear wheel, rFRJ is for the right front wheel, rFLJ is for the right front wheel, rRRJ is for the right rear wheel, and rRLJ is for the right front wheel.
means for the left rear wheel, and therefore, when there is no particular need to distinguish between them, the description will be made without using these identification symbols.

1 (IFRlIFL, IRRlI
RL) is a cylinder device provided for each front, rear, left, and right wheel, and these include a cylinder 2 connected to the unsprung weight, and a piston rod 3 extending from inside the cylinder 2 and connected to the unsprung weight. and has. Inside the cylinder 2, a liquid chamber 5 is defined above by a piston 4 integrated with a piston rod 3, and this liquid chamber 5 and a lower chamber are in communication. As a result, when the hydraulic fluid is supplied to the liquid chamber 5, the piston rod 3 extends and the vehicle height increases, and when the hydraulic fluid is discharged from the liquid chamber 5, the vehicle height decreases.

For the liquid chamber 5 of each cylinder device 1, a gas spring 6 (
6FR16FL, 6RR16RL) are connected.

Each of the gas springs 6 is composed of four cylindrical springs 7 having a small diameter, and the cylindrical springs 7 are connected to the liquid chamber 5 through an orifice 8 in parallel to each other.

Of these four cylindrical springs 7, except for one, the remaining three are connected to the liquid chamber 5 via a switching valve 9. As a result, when the switching valve 9 is in the switching position as shown, the four cylindrical springs 7 are communicated only through the orifice 8, and the damping force at this time is small. Furthermore, when the switching valve 9 is switched from the illustrated position, the three cylindrical springs 7 are also communicated with the liquid chamber 5 through the orifice 10 built into the switching valve 9, resulting in a large damping force. Become something. Of course, by changing the switching position of the switching valve 9, the spring characteristics of the gas spring 6 are also changed. The suspension characteristics can also be changed by changing the amount of hydraulic fluid supplied to the fluid chamber 5 of the cylinder device 1.

In the figure, reference numeral 11 denotes a pump driven by an engine, and high-pressure hydraulic fluid pumped up by the pump 11 from a reservoir tank 12 is discharged into a common passage 13.

The common passage 13 is branched into a front passage 14F and a rear passage 14R, and the front passage 14F is further divided into a right front passage 14F.
R and a left front passage 14FL. The front right passage 14FR is connected to the liquid chamber 5 of the front right wheel cylinder device IFR, and the front left passage 14FL is connected to the liquid chamber 5 of the front right wheel cylinder device FL. A pilot valve 16FR serving as a supply flow rate control valve 15FR1 and a delay valve is connected to this front right passage 14FR from its upstream side. Similarly, a supply flow control valve 15FL and a pilot valve 6FL are connected to the left front passage 14FL from the upstream side thereof.

A first relief passage 17FR for the right front passage is connected to the right front passage 14FR between both valves 5FR and 16FR, and this first relief passage 17FR finally passes through the front wheel relief passage 18F. It is connected to the reservoir tank 12. And in the first relief passage 17FR,
A discharge flow control valve 19FR is connected. Further, the passage 14FR downstream of the pilot valve 16FR is connected to the first relief passage 17FR via the second relief passage 20FR, and a relief valve 21FR is connected to this.

Furthermore, in the passage 14FR closest to the cylinder device IFR,
A filter 29FR is provided. This filter 29
FR is located between the cylinder device IFR and the valve 16FR121FR located closest to the cylinder device IFR.
This prevents wear particles generated from sliding of the FR from flowing toward the valve 16FR121FR.

Note that the passage configuration for the left front wheel is also configured in the same manner as the passage configuration for the right front wheel, so a redundant explanation thereof will be omitted.

A main accumulator 22 is connected to the common passage 13, and an accumulator 23F is also connected to the front wheel relief passage 18F. This main accumulator 22 serves as a pressure accumulation source for hydraulic fluid together with a sub-accumulator 24 to be described later, and is intended to prevent the amount of hydraulic fluid supplied to the cylinder device 1 from becoming insufficient. Further, the accumulator 23F is for preventing the high-pressure hydraulic fluid in the front wheel cylinder device J from being suddenly discharged to the low-pressure reservoir tank 12, that is, for preventing the water hammer phenomenon.

The hydraulic fluid supply/discharge passage for the rear wheel cylinder device IRR1IRL is also configured in the same manner as for the front wheels, so a redundant explanation thereof will be omitted. However, there is no equivalent to the pilot valve 21FR121FL in the rear wheel passage.
In addition, the main accumulator 22 is located in the rear wheel passage 114R.
A sub-accumulator 24 is provided in consideration of the fact that the passage length from the front wheel is longer than that for the front wheel.

The common passage 13, that is, each passage 14F for the front and rear wheels,
14R is connected to the front wheel relief passage 18F via a relief passage 25, and to the relief passage 25 is connected a control valve 26 consisting of an electromagnetic opening/closing valve.

In FIG. 1, 27 is a filter, and 28 is a pressure regulating valve (28) for adjusting the discharge pressure from the pump 11 within a predetermined range.
In the embodiment, the pressure regulating valve 28 is integrated into the pump 11, which is configured as a variable displacement swash plate piston type.

More specifically, this pressure regulating valve 28 functions so that the discharge pressure of the pump 11 is in the range of 120 to 160 kg/cm<2>. In other words, the discharge pressure is the lower limit of 120 kg/cm2.
When the discharge pressure is below, the pump 11 is put into a loaded state, and when the discharge pressure is above the upper limit value of 160 kg/cm2, the pump 11 is put into an unloaded state.

The pilot valve 16 is opened and closed depending on the pressure difference between the pressure in the front and rear passages 14F or 14R1, that is, the common passage 13, and the pressure on the cylinder device 1 side. Therefore, for the pilot valve 16FR116FL for the front wheels, a common pilot passage 31F branched from the passage 14F is led out, and a two-way branched from the common pilot passage 31F is led out.
One of the branch pilot passages 31FR is connected to the pilot valve 16FR, and the other passage 3IFL is connected to the pilot valve 16FR.
is connected to the pilot valve 16FL.

An onophis 32F is interposed in the common pilot passage 31F. Note that the pilot passage for the rear wheels is similarly configured.

Each of the pilot valves 16 is configured as shown in FIG. 2, for example, and the one shown is for the right front wheel. This pilot valve 16 has, in its casing 33,
A main channel 34 forming a part of the passage 14FR is formed,
A passage 14FR is connected to the main passage 34. A valve seat 35 is formed in the middle of the main flow path 34, and the opening/closing piston 36, which is slidably inserted into the casing 33, is pressed against and away from the valve seat 35, so that the pilot valve 1
6FR is opened and closed.

The opening/closing piston 36 is integrated with a control piston 38 via a valve shaft 37. This control piston 38 is
It is slidably inserted into the casing 33 to define a liquid chamber 39 within the casing 33, and the liquid chamber 39 is connected to the branch pilot passage 31FR via a control flow path 40. .

The control piston 36 is then operated by a return spring 41.
, the direction in which the opening/closing piston 36 is seated on the valve seat 35,
That is, the pilot valve 16FR is biased in the closing direction. Furthermore, the pressure of the main flow path 34 is applied to the control piston 38 via the communication port 42 on the side opposite to the liquid chamber 39 . As a result, inside the liquid chamber 39 (common passage 1
3 side) becomes 1/4 or less of the pressure in the main flow path 34 (cylinder device IFR side), the opening/closing piston 36 seats on the valve seat 35 and the pilot valve 16FR is closed.

Here, from the state where the pilot valve 16FR is open,
When the pressure in the common passage 13 drops significantly, this pressure drop is delayed by the action of the orifice 32F, and the liquid chamber 39
Therefore, the pilot valve 16FR is closed after a delay from the pressure drop (in the embodiment, this delay time is set to about 1 second).

Next, the operation of each of the above-mentioned valves will be explained.

■Switching valve 9 In the embodiment, the switching valve 9 is operated to increase the damping force only during turning.

■Relief valve 21 The relief valve 21 is normally closed and the cylinder device 1
The pressure in the example is higher than the predetermined value (160 to 200 k in the example)
g/cm2), it opens.

In other words, it serves as a safety valve that prevents the pressure in one example of the cylinder device from becoming abnormally high.

Of course, the relief valve 21 is a cylinder device IRR for the rear wheels.
Although it can also be provided for 1 IRL, in the example, it is assumed that the weight distribution is considerably larger than that of the rear wheel, and the pressure on the rear wheel side is equal to the pressure on the front wheel side. In consideration of the fact that the pressure does not exceed the pressure, the leaf valve 21 is not provided on the rear wheel side.

(2) Flow rate control valves 15.19 Both the supply and discharge flow rate control valves 15.19 are electromagnetic spool valves that can be switched between an open state and a closed state as appropriate. However, when it is in the open state, it has a differential pressure adjustment function that keeps the differential pressure between the upstream and downstream sides almost constant (due to flow rate control, this differential pressure must be kept constant). ). - More specifically, the displacement position or opening degree of the spool of the flow control valve 15.19 is changed in proportion to the supplied current, and this supplied current is determined by a flow rate-current correspondence map created and stored in advance. Determined based on. In other words, the supply current is
It corresponds to the required flow rate at that time.

By controlling the flow rate control valves 15 and 19, the supply and discharge of hydraulic fluid to the cylinder device 1 are controlled, thereby controlling the suspension characteristics.

In addition to this, when the ignition is OFF, this O
For a predetermined period of time (2 minutes in the embodiment) from the time of FF, only the control in the direction of lowering the vehicle height is performed. In other words, the vehicle height is prevented from becoming partially high (maintaining the standard vehicle height) by taking into account changes in the payload caused by getting off the vehicle, etc.
.

■Control Valve 26 The control valve 26 is normally closed by being energized, and is opened in the event of a failure. This failure can occur, for example, if part of the flow control valve 15 or 19 is stuck, if a sensor (described later) fails, if the hydraulic pressure of the hydraulic fluid fails, or if the pump 11 fails. There are cases etc.

In addition, in the embodiment, the control valve 26 is opened after a predetermined period of time (for example, 2 minutes) has elapsed since the ignition was turned off.

Note that when this control valve 26 opens, the pilot valve 1
6 is closed later as described above.

■Pilot valve 16 As already mentioned, the pilot valve 16 is opened with a delay after the pressure in the common passage 13 decreases due to the action of the orifices 32F and 32R. This means that, for example, in the event of a failure in which a part of the flow control valve 15 remains open, the pilot pressure decreases due to the opening operation of the control valve 26, resulting in passages 14FR to 14R.
L is closed to confine the hydraulic fluid in the cylinder devices IFR to IRL, and the vehicle height is maintained. Of course, at this time,
The suspension characteristics are fixed to so-called passive characteristics.

Control System FIG. 3 shows a control system for the hydraulic fluid circuit shown in FIG.

In FIG. 3, WFR is the right front wheel, WFL is the left front wheel, WRR is the right rear wheel, WRL is the left rear wheel, and U is a control unit configured using a microcomputer. This control unit U includes each sensor or switch 51FR to 51RL, 52FR to 52RL, and 53FR1.
Signals from 53FL and 53R161-63.
9FR to 19RL) and the control valve 26.

The sensors 51FR to 51RL are connected to each cylinder device IF.
It is provided at R to IRL to detect the amount of extension, that is, the vehicle height at each wheel position. Sensor 52FR~5
2RL detects the pressure in the liquid chamber 5 of each cylinder device IFR to IRL (see also FIG. 1). sensor 5
3FR153FL and 53R are G sensors that detect acceleration in the vertical direction. However, on the front side of vehicle B, two G sensors 53FR1 are installed at almost left-symmetric positions on the front axle.
53FL, but at the rear of vehicle B, only one G sensor 53R is provided at the middle position between the left and right sides on the rear axle. In this way, one virtual plane representing the vehicle body B is defined by the three G sensors, and this virtual plane is set to be a substantially horizontal plane. The sensor 6] detects the vehicle speed. The switch 62 is for switching control modes, which will be described later. The sensor 63 detects the lateral G acting on the vehicle body (in the embodiment, only one sensor is provided on the Z axis of the vehicle body).

The switches or sensors 95 to 97 are attached to the steering mechanism and are used to detect a neutral position or a steering angle. More specifically, in FIG. 6, a steering shaft 92 extending from a handle 91 and a relay rod 93 connected to left and right steering shafts are linked via a rack and pinion mechanism 94. A recess 93a is formed in this relay rod 93, and the limit switch 95 is turned on and off by the recess 93a.
be done. That is, when the relay rod 93 is in the neutral position, the operating piece of the limit switch 95 falls into the recess 93a and is turned on, and is turned off when the relay rod 93 is not in the neutral position. Further, the sensors 96 and 97 both detect the rotational position of the steering shaft 92, that is, the steering angle.
The output value is continuously variable according to changes in the steering angle. The operating state of the switch 95 is shown as θH3, the steering angle detected by the sensor 96 is shown as θH1, and the steering angle detected by the sensor 97 is shown as θH2.

The control unit U basically performs active control conceptually shown in FIGS. 4A and 4B, that is, in the embodiment, vehicle attitude control (vehicle height signal control and vehicle height displacement speed side rB).
), ride comfort control (vertical acceleration signal control), and vehicle torsion control (pressure signal control). The results of each of these controls are finally expressed as the flow rate of the hydraulic fluid flowing through the flow rate control valve 15, 19 serving as the flow rate adjusting means.

(Left below) Active control Next, an example of how to control the suspension characteristics based on the output of each sensor is shown in Fig. 4A.
This will be explained with reference to FIG. 4B.

The content of this control can be roughly divided into control systems x1 and x2 that control the attitude of the vehicle body B based on the output of the basic vehicle height sensor and its differential value (vehicle height displacement speed);
Control system X3 that performs ride comfort control based on sensor output
, a control system X4 that performs torsion suppression control of the vehicle body B based on the output of the pressure sensor, and a roll vibration reduction control system X5 based on the output of the lateral G sensor 63, which are divided as follows.

■Control XI (vehicle height displacement component) This control consists of three posture-side controls that suppress bounce, pitch, and roll, and each control is feedback control using P control (proportional control). Ru.

First, reference numeral 70 is the sum of the outputs XFR and XFL of the left and right front wheels among the vehicle height sensors 51FR to 51RL, and the output XRR of the left and right rear wheels.

This is a bounce component calculation unit that calculates the bounce component of the vehicle by summing up the X degrees. Reference numeral 71 indicates the output XR of the left and right rear wheels from the total value of the outputs XFR and XFL of the left and right front wheels.
This is a pitch component calculation unit that calculates the pitch component of the vehicle by subtracting the total value of R and XRL. Reference numeral 72 denotes a roll component calculation unit that calculates the roll component of the vehicle by adding the difference XFR-XFL between the outputs of the left and right front wheels and the difference XRR-XRL between the outputs of the left and right rear wheels. .

Reference numeral 73 receives the vehicle bounce component calculated by the bounce component calculation unit 7Q and the target vehicle height signal TH from the target average vehicle height determination unit 91, and calculates the bounce control based on the gain coefficient. This is a bounce control unit that calculates the control amount for the flow control valve of each wheel. Reference numeral 74 indicates that the pitch component of the vehicle calculated by the pitch component calculating section 71 and the target pitch amount Tp from the target pitch amount determining section 92 are manually input, and the vehicle corresponding to the target pitch amount Tp is determined based on the gain coefficient KPI. This is a pitch control unit that calculates the control amount of each flow rate control valve in pitch control so that the flow rate is high. code 7
5 is the vehicle roll component calculated by the roll component calculation unit 72 and the target roll I from the target roll amount determination unit 93.
This is a roll control unit to which TR is input and calculates the control amount of each flow control valve in roll control i based on the gain coefficients KRFI and KRRI so that the vehicle height corresponds to the target roll amount TR.

In order to control the vehicle height to the target vehicle height, each control section 7
3.74.75, the sign of each control amount is reversed for each wheel (inverted so that the sign is opposite to the sign of the vehicle height displacement signals of the vehicle height sensors 51FR to 51RL), and then, The bounce, pitch, and roll control amounts for each wheel are added, and in control system XI, the flow signals of the corresponding proportional flow control valves QFRI, QFLI, QRR
I, QRLI can be obtained.

Here, the target vehicle height TH can be kept at a certain constant value, such as 150 mm in terms of the minimum ground clearance of the vehicle. It is also possible to change the target vehicle height TH. In this case, for example, the TH can be changed stepwise or continuously depending on the vehicle height (for example, when the vehicle speed is 80 km/h or higher). (Sometimes, the minimum ground clearance is set to 130 mm). The target pitch amount Tp is O. The target roll amount TJ'l is normally O, but is set based on the lateral G in control mode 4, which will be described later, which allows reverse roll.

■Control system X2 (vehicle height displacement speed component) In the control system X2, pitch control and roll system (wholesale) are performed.

First, the pitch component from the pitch component calculation section 71 and the target pitch amount TP are input to the pitch control section 78 . This pitch control unit 78 controls the rate of change of the pitch component (which is the deviation between the vehicle height at the front of the vehicle body and the vehicle height at the rear of the vehicle body) in the direction away from the target pitch amount TP, that is, the change rate from the vehicle height sensors 51FR to 51RL. The amount of change for each signal sampling time (10 m5ec in the example) is determined.

Then, the control flow rate for each flow rate control valve is determined using the control gain KP2 so that the rate of change in the direction of increasing the pitch amount becomes smaller.

Further, the roll amount (roll angle) from the roll amount calculating section 72 and the target roll amount TR from the target roll amount determining means are input to the roll control section 79. This roll control unit 79 applies a control gain K RF2 or K )lJ to each rough layer of the left and right front wheels and the left and right rear wheels so that the rate of change in the actual roll amount in the direction away from the target roll amount TR becomes smaller. '12 is used to determine the control flow rate for each flow control valve.

The control amounts determined by each of the control units 78 and 79 are reversed in sign and then added for each flow control valve (each cylinder device IFR to IRL) to control flow rate QFR2 in the control system x 2.゜GFL2, QRR2) QRL
2 is determined. Note that "S" shown in each control unit 78 and 79 is an operator showing differentiation.

■Control system X3 (vertical acceleration component) First, reference numeral 80 indicates three vertical acceleration sensors 53FR,
Outputs GFR and GFL of 53FL and 53R.

This is a bounce component calculation unit that totals the GR and calculates the bounce component of the vehicle. Reference numeral 81 indicates the vehicle bias component by subtracting the rear wheel side output GR from the total value of each half value of the left and right front wheel side outputs GFR, GFL among the three vertical acceleration sensors 53FR153FL, 53R. This is a pitch component calculation unit that calculates. Reference numeral 82 denotes a roll component calculation unit that calculates a roll component of the vehicle by subtracting the output GFL of the left front wheel from the output GFR of the right front wheel.

Further, reference numeral 83 receives the bounce component of the vehicle calculated by the bounce component calculation unit 80, and the gain coefficient K
This is a bounce control unit that calculates the control fB amount for the flow rate control valve of each wheel in bounce control based on B3. Reference numeral 84 denotes a pitch system (which receives the pitch component of the vehicle calculated by the pitch component calculation unit 81 and calculates the control amount of each flow rate control valve in pitch control based on the gain coefficient KP3).
It is a joint. Reference numeral 85 receives the roll component of the vehicle calculated by the roll component calculation unit 82, and calculates the gain coefficient KRF.
3. A roll control unit that calculates the control amount of each flow control valve in roll control based on KRR3.

In order to suppress the vertical vibration of the vehicle with a bounce component, a pitch component, and a roll component, each control amount calculated by each of the control units 83 to 85 is reversed in sign for each wheel, and then The bounce, pitch, and roll control amounts for the wheels are added, and in the control system x3, the flow signals of the corresponding proportional flow control valves QFR3, GFL3,
QRR3 and QRL3 are obtained.

(1) Control System X4 First, a warp control section 90 is provided, which includes a front wheel side hydraulic pressure ratio calculation section 90a and a rear wheel side hydraulic pressure ratio calculation section 90b.

The front wheel side hydraulic pressure ratio calculating section 90a calculates the hydraulic pressure signals PFR, PFL of the 2@ hydraulic pressure sensors 52FR152FL on the front wheel side.
is input, and the total hydraulic pressure on the front wheel side (P FR + P F
The ratio of the left and right fluid pressure difference (P FR to PFL) to L) (
PFR-PFL) / (PFR+PFL) is calculated. In addition, the rear wheel side hydraulic pressure ratio calculating section 90b calculates a similar hydraulic pressure ratio (PRR-PRlj/(PRR0PRL)) on the rear wheel side.
Calculate.

Then, after multiplying the rear wheel side hydraulic pressure ratio by a predetermined value by a gain coefficient ωF, f4 is calculated from the front wheel side hydraulic pressure ratio, and the result is multiplied by a predetermined value by a gain coefficient ωF. Then, the control amount for each wheel is equalized between the left and right wheels.
, QRR4, and QRL4 are obtained.

Control System X5 (Lateral G Component) Control detection X5 is performed based on a signal from the lateral G sensor 63 to suppress an increase in the lateral G acting on the vehicle body and to reduce roll vibration. In this control system x5, the signal obtained by the control section 100 based on the control gain KG is
The signs are reversed for the right wheel and the left wheel, and the flow signals of the corresponding flow control valves QFR5, QFl, 5, QRR are obtained.
5. QRL5 can be obtained. Then, the control ratio between the front side and the rear side is changed by the coefficient AGF.

■Vehicle height displacement components QFRI, QFLIQRRI of the flow rate signal determined for each flow rate control valve as described above by integrating each control system X1 to x4
, QRLl, , Vehicle height displacement speed component Q FR2QFL
2, QRR2) QRL2, vertical acceleration component QFR
3, QFl3, QRR3, QRL3, pressure component Q
FR4, QFl4, QRR4, QRL4', horizontal G
Ingredient QFR5.

QFl5, QRR5, and QRL5 are finally added to produce the final total flow signals QFR, QFL, and QR.
R, QRL is obtained.

Specific examples of settings for the control gains, etc. used in FIGS. 4A and 4B are shown in Table 1 below.

In Table 1 of Table 1 and 2, the meanings of the symbols not shown in FIGS. 4A and 4B are as follows. First of all, the XH is compatible with the vehicle height signal and is used to set the dead zone.

GG corresponds to each G sensor in the vertical direction and the horizontal direction, and is used to set the dead zone. Q MAX is for setting the maximum flow rate limit for inflow and outflow. PMAx is for inlet pressure limit setting and P MIN is for outlet pressure limit setting.

Also, in the first table number, modes 1 to 7 are set, and the setting characteristics of each mode are as follows. First, mode 1 is used for 60 seconds after the engine is turned off, and is used to prevent changes in vehicle height while the vehicle is stopped. Thousand ~ Do 2
is used when the vehicle speed is zero, and is used to maintain the vehicle posture. Modes 3 to 7 are used while driving, with mode 3 emphasizing ride comfort, mode 4 setting for reverse roll, and mode 5 aiming for both ride comfort and handling stability. Mode 6 is a setting that aims to achieve both ride comfort and posture maintenance, and mode 7 is a setting that emphasizes steering stability. As shown in Fig. 5, the setting of the usage range of these modes 3 to 7 is switched using only the lateral G as a parameter, but the lateral G used for this switching is determined theoretically from the steering angle and vehicle speed. is used. And, when the lateral G is in the range of 0.1 to 0.3, whether to use control mode 4 or control mode 5 is as follows.
It is switched by the manual switch 62 mentioned above.

Note that the target vehicle height TH is changed according to the vehicle speed based on a predetermined reference vehicle height (for example, equivalent to a minimum ground clearance of 160 mm), and the target roll vehicle height TR is changed using the lateral G as a parameter.

When changing modes between modes 1 and 7, transitions to higher modes, such as from mode 3 to mode 5 or mode 1-'6, occur immediately without delay. On the other hand, when transitioning to a low mode, for example, when transitioning from mode 7 to mode 5 or mode 3, the mode is successively decreased one by one, and each time the mode decreases, a predetermined amount is set. The delay time is set. More specifically, considering the case of transitioning from mode 7 to mode 5, the change is made as follows: mode 7 - elapse of delay time - mode 6 - elapse of delay time - mode 5.

Selection of control mode Next, referring to the flowchart shown in Fig. 7,
The details of the control mode selection will be explained below. In the following explanation, P indicates a step.

First, at Pl, each switch or sensor 61.
The outputs from 95 to 97 are read. That is, sensor 6]
Then, the detected vehicle speed is ■, the ON/OFF signal as the neutral position signal from the switch 95 is read as θH3, the detected steering angle from the sensor 96 is read as θH], and the detected steering angle from the sensor 97 is read as θH2. .

At P3, it is determined whether θH3 is ON, that is, whether the steering mechanism is currently in the neutral position. When the determination of P2 is YES, the sensor 96.
After the zero point is corrected so that the detected steering angles θH1 and θH2 at 97 correspond to the neutral position, at P4,
The lateral acceleration is theoretically determined based on the steering angle θH1 (the same 2 for θH2) and the vehicle speed ■. After this, at Pl6, the map shown in Fig. 5 is changed, that is, the vehicle speed
The control mode is selected based on the theoretical lateral acceleration and the theoretical lateral acceleration (basic control mode selection).

When the determination in P2 is No, in P5, eHl
It is determined whether or not θH2 and θH2 substantially match, that is, whether there is a deviation in the detected steering angle. If the determination in P5 is YES, it means that there is no deviation in the detected steering angle, and in this case, the process moves to P4 described above, and the control mode is selected based on the theoretically obtained lateral acceleration. It is done.

When the determination in P5 is No, it means that there is a deviation in the detected steering angle. In the second case, press P6) to cancel control mode 3 and control mode 4 for reverse roll.
In other words, the selection of the corresponding Ryowari (wholesale modes 3 and 4) is prohibited. After that, in P7, eHl is differentiated to obtain the steering angular velocity θH]·S, and θ+−(2 is differentiated to obtain the steering angular velocity θ2·
S is calculated.

After Pl, in P8, it is determined whether θHl·S is greater than or equal to θH2·S. When the determination in P8 is YES, in P9 a pseudo lateral acceleration GA is determined based on eHl·S and vehicle speed ■. Further, when the determination in P8 is No, a pseudo lateral acceleration GA is determined in PIO based on eHl·8 and vehicle speed ■.

In this way, the pseudo lateral acceleration GA is determined by the processes P8 to PIO based on the larger steering angular velocity and vehicle speed.

After P9 or P2O3, the vehicle speed is 8 at pH.
It is determined whether or not it is 0 km/h or more. If YES in this pH determination, control mode 7, which places the greatest emphasis on stability, is selected at Pl5.

When the above pH determination is NO, it is determined at Pl2 whether the pseudo lateral acceleration GA is less than or equal to a reference value (for example, equivalent to 0.3G). When the determination of Pl2 is YES, control mode 5 is selected in Pl3, and P]2
If the determination is No, control mode 6 is selected at Pl4.

FIGS. 8 and 9 show an example in which five control modes are selected depending on lateral G (theoretical lateral acceleration obtained from the steering angle and vehicle speed) and vehicle speed V, FIG. 8 shows a selection mode in a range that does not include control mode 4 in which reverse roll is performed by the switch 62, and FIG.
This shows a selection mode in a range including control mode 4 in which a reverse roll is performed. Note that FIGS. 8 and 9 correspond to FIG. 5, and are the basic selection mode at P4 in FIG. 7. In the cases shown in FIGS. 8 and 9 as well, if a deviation occurs in the detected steering angle, the above-mentioned processes from P6 onwards may be performed.

Although the embodiment has been described above, when a deviation occurs in the detected steering angle, it may be possible to select only a certain control mode, for example, control mode 7, or to select a control mode using only the vehicle speed as a parameter. Alternatively, the control mode may be withdrawn based only on the pseudo lateral acceleration.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of the overall circuit of an active suspension. FIG. 2 is a sectional view showing an example of the pilot valve in FIG. 1. FIG. 3 is a diagram showing a control system of the circuit shown in FIG. 1. FIGS. 4A and 4B are overall system diagrams showing an example of active control. FIG. 5 is a diagram showing an example of setting the usage area of each control mode using only lateral acceleration as a parameter. FIG. 6 is a simplified perspective view showing the steering mechanism along with a neutral position detection switch and two steering angle sensors. FIG. 7 is a flowchart showing a control example of the present invention. FIGS. 8 and 9 are diagrams showing examples of setting the usage range of each control mode using parameters such as lateral acceleration and vehicle speed. ■ IFR~ IRL 5FR~ 15RL 9FR~ l 9RL: Cylinder device: Supply control valve: Discharge control valve: Vehicle speed sensor: Handle/steering shaft: Relay rod: Neutral position detection switch 2 Rudder angle sensor: Rudder angle sensor 2nd control unit 4゜5 Fig. 8 Fig. Vehicle speed (km/h) Fig. 9 Width # (krn/h)

Claims (7)

[Claims] (1) A cylinder device installed between the vehicle body and each wheel, which adjusts the vehicle height according to the supply and discharge of working fluid; Attitude control means for controlling the attitude of the vehicle body by controlling air supply and evacuation; Rudder angle detection means for detecting a steering wheel angle; Vehicle speed detection means for detecting vehicle speed; and Rudder angle detected by the steering angle detection means. and a lateral acceleration determining means for determining the lateral acceleration acting on the vehicle body from the vehicle speed detected by the vehicle speed detecting means, and a plurality of control modes including a control mode for performing a reverse roll as the control mode, basic control mode selection means for selecting a control mode to be used by the attitude control means from among a plurality of control modes based on the lateral acceleration detected by the lateral acceleration detection means; and a rudder angle detected by the rudder angle detection means. a deviation detecting means for detecting that a deviation has occurred in the detected steering angle; A suspension device for a vehicle, comprising: provisional control mode selection means for selecting a control mode other than a control mode for performing reverse roll from among the plurality of control modes as a control mode to be used. (2) In claim 1, a steering angle speed determining means for determining a steering angle speed by differentiating the steering angle detected by the steering angle detecting means; a steering angle speed determined by the steering angle speed determining means and the steering angle speed determined by the steering angle speed determining means; Pseudo lateral acceleration determining means for pseudo-determining lateral acceleration from the vehicle speed detected by the vehicle speed detecting means, wherein the provisional control mode selecting means is configured to determine the pseudo lateral acceleration determined by the pseudo lateral acceleration determining means. A control mode to be used by the attitude control means is selected based on the following. (3) Claim 1, wherein the temporary control mode selection means selects the control mode used by the attitude control means based on the vehicle speed detected by the vehicle speed detection means. (4) The vehicle according to claim 1, wherein the temporary control mode selection means selects a control mode that improves stability of the vehicle body more than the control mode that performs the reverse roll. (5) In claim 1, a steering angle speed determining means for determining a steering angle speed by differentiating the steering angle detected by the steering angle detecting means; a steering angle speed determined by the steering angle speed determining means and the steering angle speed determined by the steering angle speed determining means; Pseudo lateral acceleration determining means for pseudo-determining lateral acceleration based on the vehicle speed detected by the vehicle speed detecting means, wherein the temporary control mode selecting means determines that the vehicle speed detected by the vehicle speed detecting means is equal to or higher than a predetermined vehicle speed. When the vehicle speed is lower than the predetermined vehicle speed, the pseudo lateral acceleration determined by the pseudo lateral acceleration determining means is selected. One that selects the control mode based on lateral acceleration. (6) In claim 1, there is provided neutral detection means for detecting that the steering wheel is in the neutral position; and when the neutral detection means detects that the steering wheel is in the neutral position, the steering angle detection means and a correction means for correcting the deviation of. (7) In claim 1, the rudder angle detection means is constituted by two rudder angle detection means, a first rudder angle detection means and a second rudder angle detection means, and the deviation detection means comprises: It is determined whether or not a deviation has occurred in the detected steering angle by comparing detection values of the first steering angle detection means and the second steering angle detection means.