JP3069794B2 - Vehicle suspension device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a vehicle suspension apparatus provided with a damping force variable damper capable of changing a damping force.

(Conventional technology) Conventionally, a damping force variable damper capable of switching the magnitude of the damping force in a plurality of steps or continuously changing the magnitude is known.

In a conventional vehicle suspension device having such a damping force variable damper, as described in, for example, JP-A-57-151307, a lateral load for suppressing rolling during turning is generated. When turning (during turning), the damper is set to a high damping force (hard), and furthermore, the hard state is maintained for a certain period of time even after the end of turning in order to prevent deterioration in stability due to recoil (swing back) at the time of rolling restoration Is performed.

(Problems to be Solved by the Invention) However, the following problems occur in the case where the hard state is constantly maintained during turning as in the above-described related art.

That is, in the hard state of the damping force variable damper, the traveling speed of the rolling can be suppressed, but the occurrence of the rolling itself cannot be suppressed. Therefore, if the turning operation is performed continuously for a long time to some extent, the rolling progresses even in the hard state, so that in a steady turning state in which the steering wheel is maintained at a substantially constant steering angle, the vehicle body posture eventually becomes the roll moment and the spring reaction force. When the equilibrium point is reached, the roll angle becomes constant and the rolling saturation occurs.

In the above prior art, the damper is fixed to the hard state during turning, so that the hard state is maintained even when the state shifts to the rolling saturated state.

Therefore, in the prior art, the intended purpose is not achieved in the rolling saturated state, that is, the damping force of the damper has the function of suppressing the rolling only when the roll angle is changing, so that the roll angle does not change. In the rolling saturated state, even if the damper is in a hard state or a soft (low damping force) state, not only can the rolling progress not be suppressed, but also by such a hard state, it is caused by unevenness of the road surface The unsprung vibration is transmitted to the sprung, causing a rugged feeling, and there is a problem that the riding comfort in a steady turning state, particularly in a rolling saturated state, is deteriorated.

Further, in the above-described prior art, since the hard state is consistently obtained at the time of the rolling restoration, the operability can be maintained satisfactorily, but the rolling restoration (recovery of the vehicle body posture) is greatly delayed. Therefore, there is a problem that the rolling restoring time becomes longer (the rolling state is maintained for a certain period of time even after the end of the turn), and the hard state is maintained during such a long rolling restoring time, so that the riding comfort time becomes longer.

SUMMARY OF THE INVENTION In view of the above circumstances, an object of the present invention is to improve the riding comfort by speeding up the rolling restoration at the time of the rolling restoration and shortening the time of the hard state, while suppressing the progress of the rolling and preventing the swingback at the time of the rolling restoration. A vehicle suspension device is provided.

(Means for Solving the Problems) In order to achieve the above object, a first invention of the present application provides a damping force variable damper capable of changing a damping force according to a driving state of a vehicle, and a damping force of the damper. At the start of the turning operation, a high damping force is used, at the time of a steady turning, a low damping force is used, and at the time of the turning end operation, a low damping force is used when the vehicle body roll angle is a predetermined value or more.
And damping force control means for increasing the damping force when the vehicle body roll angle falls below the predetermined value.

The low damping force and the high damping force are relative to each other, and the low damping force has a smaller damping force compared to the high damping force.
The high damping force means a larger damping force than the low damping force (the same applies to the following second invention).

To make the damping force low at the time of steady turning mainly means to make the damping force low, and also includes the one that makes the damping force low and includes a little high damping force depending on the situation. Further, the low damping force may be set only at the time of rolling saturation during the steady turning.

Further, the damper may be a damping force switching type or a continuously changing type (the same applies to the second invention described below).

According to a second aspect of the present invention, in order to achieve the above object, a damping force variable damper capable of changing a damping force according to a driving state of a vehicle, the damping force of the damper being a high damping force at the start of a turning operation, At the time of steady turning, high damping force is used, and at the time of turning end operation, low damping force is used when the vehicle body roll angle is a predetermined value or more,
And damping force control means for increasing the damping force when the vehicle body roll angle falls below the predetermined value.

(Operation) In the first and second aspects of the invention, the damper is in the hard state at the time of turning start operation, so that rolling during turning is suppressed, and at the time of turning end operation, the vehicle body roll angle is equal to or more than a predetermined value. In this case, the damper is in the soft state, so that the rolling restoration is hastened.In addition, the damper is in the hard state when the vehicle body roll angle is less than the predetermined value, instead of maintaining the soft state. Prevents swaying during rolling restoration,
Eventually, the rolling restoring time is reduced while preventing the swing-back during the rolling restoring, and the deterioration of the riding comfort due to the long-time hard state during the rolling restoring can be prevented.

(Embodiment) Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

(A) First Embodiment Device Configuration FIG. 1 is a perspective view showing the configuration of a first embodiment of the suspension device of the present invention.

As shown in the figure, in the present embodiment, damping force variable dampers 2a, 2b, 2c, 2d attached to each wheel, and damping force switching actuators 4a, 4b, 4c, 4d built in each damper, respectively. , Vehicle height sensors 6a, 6b, 6
c, 6d, acceleration sensors 8a, 8b, 8c, 8d provided at four positions in front, rear, left and right of the vehicle body, a vehicle speed sensor 10, a steering angle sensor 12,
It comprises an accelerator opening sensor 14, a brake pressure sensor 16, a mode selection switch 18, and a control unit 20.

Note that a, b, c, and d attached to the numbers of the dampers and the like indicate the following vehicle positions.

a: front of the vehicle, left side in the direction of travel b: front of the vehicle, right side of the direction of travel c: rear of the vehicle, left side of the direction of travel d: rear of the vehicle, right of the direction of travel It is a block diagram which shows the connection relation of each said component. Hereinafter, description will be made with reference to FIGS. 1 and 2.

The damping force variable dampers 2a to 2d attenuate the force acting between the vehicle body (above the spring) and the axle (below the spring), and reduce the damping force between hard (high damping force) and soft (low damping). And force).

Each of the actuators 4a to 4d has a solenoid as described below, and switches the damping force of a damper attached to each of the two stages of hardware and software by turning on and off the solenoid. Switching is performed based on a control signal v _a to v _d from the control unit 20. The actuator control signals v _{a to} v _d take two values of 1,0. At 1, the solenoid of the actuator is not energized and the damper is in a hard state. When the value is 0, the solenoid of the actuator is energized, and the damper enters a soft state.

The vehicle height sensor 6a~6d is for detecting the relative displacement between the vehicle body and the axle at each wheel portion, and outputs toward a relative displacement signal l _a to l _d between the vehicle body axle to the control unit 20. The signal l _a to l _d takes a continuous value, is positive when the damper extends, and negative when the contraction. It should be noted that the relative displacement when the vehicle is stationary is set to 0, and the magnitude of the relative displacement is represented by a deviation from the relative displacement.

The acceleration sensor 8a~8d is for detecting an acceleration (Z direction of FIG. 1) vertical direction of the vehicle body at a predetermined position of the vehicle longitudinal and lateral, vertical body absolute acceleration signal _Ga ~
_Gd is output to the control unit 20. The signals _Ga to _Gd take continuous values, and are positive when the vehicle body receives an upward acceleration and negative when the vehicle body receives a downward acceleration.

The vehicle speed sensor 10 detects a vehicle speed, and outputs a vehicle speed signal to the control unit 20. The vehicle speed signal takes a continuous value, and is positive when the vehicle moves forward,
It is negative when retreating.

The steering angle sensor 12 detects a steering angle of the steering wheel, and outputs a steering angle signal to the control unit 20. The steering angle signal takes a continuous value, positive when the steering wheel rotates counterclockwise as viewed from the driver's side, and negative when the steering wheel rotates clockwise.

The accelerator opening sensor 14 detects an accelerator opening (accelerator pedal depression amount), and outputs an accelerator opening signal to the control unit 20. The accelerator opening signal takes a continuous value.

The brake pressure switch 16 detects whether or not the brake is operating based on the brake fluid pressure, and outputs a brake pressure signal to the control unit 20.
The brake pressure signal takes two values, ON and OFF. ON means that the brake is being operated, and OFF means that the brake is not being operated.

The mode selection switch 18 is a switch for the driver to select one of hardware, software, and control modes. A mode selection signal (a signal indicating the mode selected by the driver) is output to the control unit 20. You. The mode selection signal includes a plurality of (three in this embodiment) 2
It is a parallel signal composed of value signals and takes three values: hardware, software, and control. Hard means that the driver has selected the hard mode, software means that the soft mode has been selected, and control means that the control mode has been selected. As will be described later, in the case of hardware, all dampers are fixed in the hard state, in the case of software, all dampers are fixed in the soft state, and in the case of control, the hard / soft state of each damper is determined according to the vehicle motion state and operation state. Automatically switched.

The control unit 20 determines the actuator control signals v _{a to} v _d based on signals input from the respective sensors and switches, and determines the actuator control signals v _{a to} v _d based on the signals.
Output to 4d.

Next, the structure of the damping force variable damper will be described. 3A and 3B are partial cross-sectional views of the damping force variable damper. FIG. 3A shows a hard state, and FIG. 3B shows a soft state.

The variable damping force damper consists of a piston unit 22 and a cylinder.
24, each of which is connected to the vehicle body (above the spring) and the axle (below the spring) via a separately provided connecting structure. The piston unit 22 includes a piston 26, a piston rod 28, an actuator 30, and the like.
The inside of 4 is partitioned into an upper chamber 32 and a lower chamber 34 by the piston 26. The piston unit 22 is provided with two orifices 36a and 36b. The orifice 36a is always open, but the orifice 36b can be opened and closed by the actuator 30. The upper chamber 32, the lower chamber 34, and the cavity in the piston unit 22 communicating therewith are filled with a fluid having an appropriate viscosity. The fluid comprises an orifice 36a and / or
Alternatively, it can move between the upper chamber 32 and the lower chamber 34 through the orifice 36b. The actuator 30 includes a solenoid 38, a control rod 40, and two springs 42a, 42b.
Consists of The control rod 40 moves up and down in the piston rod 28 by the magnetic force received from the solenoid 38 and the force received from both springs 42a and 42b, and at this time the orifice 36b is opened and closed.

 Hereinafter, two states of the damper will be described.

(A) Hard state (FIG. 3A) When the solenoid 38 is not energized, the force of the spring 42a pushing the control rod 40 downward is greater than the force of the spring 42b pushing the control rod 40 upward.
40 is pressed downward and orifice 36b closes. Therefore, the passage of the fluid is only the orifice 36a, and the damper is in a hard state.

(B) Soft state (Fig. 3B) When the solenoid 38 is energized, the control rod
As 40 is lifted upward, orifice 36b opens. Therefore, both the orifices 36a and 36b pass through the fluid, and the damper is in a soft state.

Since the damper is in the hard state when the power is not supplied as described above, even if the control unit 20 fails, the damper is kept in the hard state, and the deterioration of the operability is prevented.

Basic control Next, each damper 2a-2d by the control unit 20
Will be described. FIG. 4 is a flowchart of such basic control.

This basic control operation is executed by a control program installed in the control unit 20. This control program is repeatedly started at a fixed period (1 to 10 ms) by a separately provided start program. The normal control flag in the figure is a virtual switch placed in a memory or the like in the control unit 20, and takes two values, ON and OFF. The normal control flag is initialized to ON at the start of the operation of the control unit 20 by an initialization program provided separately.

 Hereinafter, the basic control operation will be described along the flow.

(1) First, in S1, it is determined whether the normal control flag is ON. If the normal control flag is set to OFF for some reason, the operation is terminated without performing the following control. Otherwise, proceed to S2.

(2) In S2, it is determined whether or not the mode selection signal is hard. If the mode selection signal is hard, proceed to S12, v
Set 1 to _{a to} v _d and output. As a result, all the dampers are in the hard state. At this time, the operation is completed. If the mode selection signal is not hardware, the process proceeds to S3.

(3) In S3, it is determined whether or not the mode selection signal is soat. If the mode selection signal is soft, proceed to S13, v
0 is set to output to _{a ~v d.} As a result, all the dampers are in the soft state. At this time, the operation is ended as follows. If the mode selection signal is not soft, the operation proceeds to the next operation (S4 to S11).

The following operations (S4 to S11) are performed only when the mode selection signal is neither hardware nor software, that is, control.

(4) In S4, entering between the vehicle body axle relative displacement signal l ₁ to l _4.

(5) In S5, l _{a to} l _d are differentiated by a numerical differentiation method or the like to obtain relative speeds _a to _d between the vehicle axles.

(6) In S6, the vertical vehicle absolute acceleration signal _Ga
Enter ~ _Gd .

(7) In S7, _Ga to _Gd are integrated by a numerical integration method or the like to obtain vertical vehicle body absolute velocities _Ga to _Gd .

(8) In S8, since _Ga ~ _Gd previously obtained is a vertical body absolute velocity in the acceleration sensor position, the vertical direction of the vehicle body absolute velocity _Sa ~ at each damper position this
Convert to _Sd . Incidentally, _Sa ~ _Sd, of the _Ga ~ _Gd, will be asked if 3 Tsugawaka', below, _Ga
To _Gc , and _Gd is a reserve value.

Set the origin properly in the horizontal plane, and set the xy coordinates (see Fig. 1)
The coordinates of the acceleration sensors 8a to 8c when (x _Ga , y
_{Ga) ~ (x Gc, y} Gc), the coordinates of the damper _{2a~2d (x Sa, y Sa)} ~
When (x _Sd , y _Sd ), _Sa to _Sd are obtained by the following equations.

However, the two coefficient matrices and their product are obtained in advance and given as constants.

(9) In S9, it obtains the determination function h _a to h _d by the following equation.

h _i = _{i Si} (i = a, b, c, d) (10) In S10, the values of the actuator control signals v _{a to} v _d are determined by the following method.

If h _i ≧ 0, v _i = 1 if h _i <0, v _i = 0 (i = a, b, c, d) (11) In S11, output v _{a to} v _d and end the operation I do.

By the basic control described above, the phenomenon that high-frequency vibration input from the road surface to the unsprung portion is transmitted to the spring and the phenomenon that low-frequency vibration input from the road surface to the unsprung portion excites resonance on the spring are both appropriate. And a good ride comfort without a feeling of lumps and fluffiness is realized.

Note that the above basic control can take either a soft state or a hard state. However, basically, the soft state is mainly used, and the hard state is appropriately set according to the situation.

Auxiliary control Next, each damper 2a-2d by the control unit 20
The auxiliary control (control during turning traveling) will be described. 5 and 6 are flowcharts of the auxiliary control. FIG. 5 shows a steering angular velocity calculation flow, and FIG. 6 shows a control flow when rolling occurs.

These auxiliary control operations are executed by two programs mounted on the control unit together with the basic control program. These programs, like the basic control program, are repeatedly started at a fixed period (1 to 10 ms) by a separately provided start program.

Hereinafter, these auxiliary control operations will be described along the flow.

(A) Calculation of steering angular speed (FIG. 5) In step S14, a steering angle signal θ is input, and in step S15, a steering angular speed is obtained by differentiating the steering angle signal by a numerical differentiation method or the like. θ is stored on a memory in the control unit 20.

(B) Rolling control (FIG. 6) First, in S16, the absolute value of the steering angular velocity (Positive fixed value) or not, In the above cases (at the time of turning start operation or turning end operation), S2
Proceeding to 1, 22, 23, the normal control flag is turned off, and 1 is substituted for all of v _a to v _d and output (all damper hard state). Turning off the normal control flag invalidates the basic control.

Is the absolute value of Less time proceeds to S17, S18, and vehicle body axle relative displacement l _a
Enter a to l _d, body roll angle them based on [psi _{x (Seventh}
(Refer to the figure), and then go to S19 to determine the absolute value of θ. It is determined whether the value is (positive-constant value) or more. The subsequent control is
There are two cases depending on the value of θ.

B The absolute value of θ is When smaller (when little steering operation is performed)
Proceeds to S20, the absolute value of [psi _x is epsilon _{2 (positive} - definite) determines whether it is greater than. The subsequent control is divided into two cases depending on the value of _ｘx .

ψ when the absolute value of epsilon ₂ or more _x (when not yet fully recovered the vehicle body posture), the flow proceeds to S21, S22, S23, the normal control flag to OFF, 1 is substituted into v _a to v _d Output. (All damper hard state) [psi absolute value epsilon ₂ smaller than when _x (when fully vehicle body attitude is restored), the flow proceeds to S27, and ends the operation by the normal control flag to ON. Turning on the normal control flag enables the basic control.

B The absolute value of θ is More time proceeds (steady turning) in S24, S25, and inputs the vehicle speed signal, the absolute value of the vehicle speed and to estimate the maximum roll angle [psi _xmax from the steering angle theta, further proceeds to S26 ψ _xmax -ψ _x is ε
_{1 It} is determined whether it is equal to or more than (positive minus fixed value). Subsequent control is the value of ψ _xmax -ψ _x divided into two cases.

ψ _xmax -ψ when the absolute value of epsilon ₁ or more of the _x (when the roll angle does not reach the saturation point), the flow proceeds to S21, S22, S23, the normal control flag to OFF, 1 to v _a to v _d substituted and outputs (total damper hard state) ψ _xmax -ψ absolute value epsilon ₁ less than the time of _x (when the roll angle reaches the saturation point), the flow proceeds to S27, the operation and the normal control flag to oN finish.

In the above embodiment, the maximum roll angle _ψxmax is estimated from the vehicle speed and the steering angle θ. For example, a lateral acceleration sensor is provided, and the value of the lateral acceleration obtained by this is used.
_xmax may be estimated.

FIG. 8 shows an example of actual suspension control at the time of turning traveling based on the above basic control and auxiliary control.

(1) The part (A) in the figure is in a straight running state, in which the steering operation has not been performed yet, so that the basic control is performed (case -a- above).

(2) Next, when steering is started from the straight running state and the state shifts to the turning start operation state (B), it is detected that the turning start operation has been started, and the damper is fixed to the hard state (the above case). . At the time of the turning start operation, || becomes large. Therefore, it is determined whether or not the turning start operation is being performed based on the magnitude of ||.

As a result, the rolling speed during turning is suppressed. Even in the stage where the vehicle turns to the steady turn, if the vehicle body roll angle has not reached the saturation point, the hard state is kept fixed (case (b) above). Whether reached saturation point is determined by whether the difference between [psi _x and [psi _xmax is sufficiently small (epsilon ₁ or less).

(3) When the vehicle enters a steady turning state and the vehicle body roll angle ψx reaches a state (C) in which the vehicle body roll angle ほ ぼ_x has almost reached the saturation point, the above-described basic control mainly in the soft state is performed (the above-mentioned case (b)). Thereby, at the time of steady turning state as in the prior art,
In particular, the riding comfort in the steady turning state is improved as compared with the case where the rolling saturated state is set to the hard state.

(4) Then, reverse the handle (to return to the neutral position)
When turning to the turning end operation state (D), it is detected that the turning end operation state has been entered, and the damper is fixed to the hard state (the above case). Since || also increases during the turning end operation, it is determined whether or not the turning end operation is being performed based on the magnitude of ||. This allows
The recoil at the time of rolling restoration is suppressed, and the deterioration of maneuverability is prevented.

Further, even when the turning end operation is completed and the steering wheel returns to the neutral position, the hard state is still maintained as long as the vehicle body posture has not been sufficiently recovered (case (a) above).

(5) When the turning end operation has been completed and the vehicle body posture has fully recovered (E), the control returns to the basic control (the above case).

(B) Second Embodiment The first embodiment is an example in which a damper capable of switching the damping force between two stages of hard and soft is used. Next, the damping force is hard and normal (medium damping force). An example using a damper that can be switched to three stages of software will be described.

 First, the configuration of the damper will be described.

9A and 9B are partial cross-sectional views of the damper. No.
FIG. 9A shows a hard state and FIG. 9B shows a soft state.
Except for having two solenoids 38a and 38b, this damper has the same configuration as the damper shown in FIGS. 3A and 3B. Therefore, the same components are denoted by the same reference numerals and description thereof is omitted. I do.

In this damper, three states of hard, normal, and soft can be set by appropriately controlling energization and non-energization of the two solenoids 38a and 38b.

That is, by energizing only the solenoid 38b, the control rod 40 moves downward and enters the hard state shown in FIG. 9A. Further, by conducting only the solenoid 38a, the control rod 40 moves upward and enters the soft state shown in FIG. 9B. Further, when both the solenoids 38a and 38b are energized or de-energized, the control rod 40 moves to the neutral position and enters the normal state.

The hard state and the soft state are high and low attenuation states as in the first embodiment, but the normal state is adjusted so as to obtain characteristics close to those of a conventional damper having no variable characteristics. . The adjustment is performed by the springs 38a, 38
This can be done by adjusting the rigidity of b and adjusting the neutral position of the control rod 40.

In this damper, the control unit 20
If it fails, it will naturally maintain its normal state,
At the same time as preventing the deterioration of the maneuverability, a better riding comfort than in the first embodiment can be obtained.

 FIG. 10 is a block diagram showing the configuration of the second embodiment.

In the second embodiment, since two solenoids 38a and 38b must be driven, two control signals are required for one actuator. V _Hi to v _Si in the figure
(I = a, b, c, d) are solenoid 38b and solenoid 3, respectively.
8a, which takes two values, 1 and 0 (1 when energized, 0 when not energized). The relationship between the value of each signal and the damper characteristic is as follows.

v _Hi is 1, v _Si is 0 ... Hard state v _Hi is 0, v _Si is 1 ... Soft state v _Hi is 1, v _Si is 1 ... Normal state v _Hi is 0, v When _Si is 0: Normal state (i = a, b, c, d) The configuration of the second embodiment is the same as that of the first embodiment except that two control signals are output to each of the actuators. Same as the example.

FIG. 11 shows a basic control flow of the second embodiment, and FIG. 12 shows a control flow when rolling occurs in the second embodiment.

The basic control operation and the control operation when rolling occurs in the second embodiment are exactly the same as those in the first embodiment. However, in the second embodiment, the output to each actuator when setting the hardware state and the soft state is performed. Since the control signal to be performed is different from that in the first embodiment, only the part is changed. That is, instead of outputting 1 as the value of v _i , 1 is output as the value of v _Hi and 0 is output as the value of v _Si (hard state).

Instead of outputting 0 as the value of v _i , 0 is output as the value of v _Hi and 1 is output as the value of v _Si (soft state).

The control contents in the first and second embodiments are summarized as follows. That is, when the occurrence of the lateral load is predicted or detected, the characteristics of the damper are made hard. However, in the following cases, the characteristics are made more soft.

When the absolute value of the steering angular velocity is small, the steering angle is small, and the difference between the estimated maximum vehicle body roll angle predicted from the lateral load and the actual vehicle body roll angle is small. The force equilibrium point has been reached).

When the absolute value of the steering angular velocity is small, the steering angle is small, and the actual vehicle roll angle is small (at this time, the vehicle body posture is fully restored).

(C) Third Embodiment Next, a suspension device according to a third embodiment will be described.

Since the device configuration and the basic control of the present embodiment are the same as those of the first embodiment, a description thereof will be omitted, and only the auxiliary control executed during turning will be described below.

Auxiliary Control Auxiliary control is composed of two operations, i.e., steering angle speed calculation and rolling occurrence control, as in the first and second embodiments. The steering angular velocity calculation flow is the same as in the first embodiment (FIG. 5). The control flow at the time of rolling occurrence is as shown in FIG.

These auxiliary control operations are executed by two programs mounted on the control unit together with the basic control program. These programs, like the basic control program, are repeatedly started at a fixed period (1 to 10 ms) by a separately provided start program.

Hereinafter, these auxiliary control operations will be described along the flow.

(A) Calculation of steering angle speed (FIG. 5) The steering angle signal θ is input and differentiated by a numerical differentiation method or the like to obtain the steering angle speed. θ is stored on a memory in the control unit 20.

(B) Rolling control (Fig. 13) First, in S50, the absolute value of the steering angular (Positive constant value) or more, and if NO, the absolute value of the steering angle θ (Positive constant value) is determined. And S50, S51
If both are NO, that is, the absolute value is smaller and θ
When the absolute value of is smaller than θ (when the steering operation is hardly performed), the process proceeds to S52, the normal control flag is turned on, and the operation is ended. Turning on the normal control flag enables the basic control.

If NO in S50 and YES in S51, the absolute value of Smaller and the absolute value of θ is When the above process proceeds to (steady turning time) of S53, S54, S55, and the normal control flag to OFF, v _a ~v _d substituting all 1 and outputs (all dampers hard state). Turning off the normal control flag invalidates the basic control.

If YES in S50, the process proceeds to S56, where it is determined whether the product of the steering angle θ and the steering angular velocity is positive or negative. If both S50 and S56 are YES, that is, the absolute value of If it is larger and the product of θ is positive (while the steering is rotating in a direction away from the neutral position; during the turning start operation), the process proceeds to S53, S54, and S55, and the normal control flag is set to O.
Set to FF, assign all 1 to v _a to v _d , and output (all damper hard state).

If S50 is YES and S56 is NO, the absolute value of If it is larger and the product of θ is negative (while the steering is rotating in the direction approaching its neutral position; during the turning end operation), the normal control flag is turned off in S57, and the relative axle relative to the body axle is set in S58. The displacement signals l _{a to} l _d are input, and based on these, the body roll angle で_x is obtained in S50, and the process proceeds to S60, where ψx is obtained.
The absolute value of _x is preset (Positive constant value) is determined. The subsequent control is
ψ There are two cases depending on the value of _x .

B) The absolute value of _x If it is smaller (when the vehicle body posture has been sufficiently restored), the process proceeds to S54, in which all 1 are substituted for v _a to v _d and output (all damper hard state).

B The absolute value of _x In the above cases (when the body posture has not yet been fully restored)
Proceeding to S61, all 0s are substituted for v _a to v _d and output (all damper soft state).

FIG. 14 shows an example of actual suspension control at the time of turning traveling based on the above basic control and auxiliary control.

(1) The portion (A) in the figure is in a straight running state, in which the steering operation has not yet been performed, so that the basic control is performed (the above case).

(2) The steering is started from the straight running state, and the turning start operation (part (B) in the figure) is started, and at the same time, the hard state is fixed (the above case). Then, even if the routine shifts to the steady turning as it is, the hard fixed state is maintained (the above case). This suppresses the speed of rolling.

(3) When turning the steering wheel in the reverse direction (in the direction of returning to the neutral position) and entering the turning end operation, if the vehicle body roll angle is large, that is, in the state of FIG. B). As a result, the vehicle body posture can be quickly recovered as compared with the related art in which the hard state is maintained.

(4) If the vehicle body roll angle becomes sufficiently small following the above (C) (state (D) in the figure), or if the vehicle body roll angle has already become sufficiently small when entering the turning end operation, It is fixed in a hard state (case -a). As a result, it is possible to suppress the recoil at the time of restoring the vehicle body posture, and to prevent deterioration of the maneuverability.

(5) When the steering operation is completed, the process returns to the basic control (see above).

(B) Fourth Embodiment Next, a fourth embodiment will be described.

 FIG. 15 is a block diagram showing the configuration of the fourth embodiment.

The configuration of the fourth embodiment is basically the same as that of the third embodiment, but differs from the third embodiment in the following two points.

First, the actuators from the control unit 20
The actuator control signals v _{a to} v _d output to 4a to 4d are
It can take three values i ₀ , 0, −i ₀ , and is provided with constant current power supplies 44 a to 44 _d for supplying a signal i ₀ to each of the actuator control signals v _{a to} v _d .

Further, the damper is configured to be able to switch between three stages of hardware, normal and software. That is, 2i
_When the current of ₀ is given, it is soft, when the current of i ₀ is given, it is normal, and when the current is 0, it is hard.
The rigidity of the two springs 42a, 42b is determined. The normal is adjusted so as to obtain characteristics close to those of a conventional damper having no variable characteristics.

In the fourth embodiment configured as described above, to obtain the hardware characteristics, the control unit 20 may output a signal having a value of -i ₀ , ₀ for normal, and i ₀ for soft. . Therefore, the control unit 20
In the event of a failure, the damper naturally keeps the normal state, preventing deterioration of the maneuverability and, at the same time, providing a better ride quality than in the third embodiment.

16 and 17 show a basic control flow and a control flow when rolling occurs in the fourth embodiment. These flows perform exactly the same operation as the flows of the same name in the third embodiment, and differ from the third embodiment only in the following points.

Instead of outputting 1 as the value of v _{a to} v _d , −i ₀ is output. (Hard state) Instead of outputting 0 as the value of v _{a to} v _d , i ₀ is output. (Soft state) The control contents in the third and fourth embodiments are summarized as follows. That is, when the occurrence of the lateral load is predicted or detected, the characteristics of the damper are made hard. However, when the steering wheel moves in the direction to return to the neutral position (that is, at the time of the turning end operation), the following control is performed.

When the vehicle body roll angle is large (when the vehicle body posture has not yet been sufficiently restored), the damper is softened.

When the vehicle body roll angle is small (when the vehicle body posture is fully restored), the damper is hardened.

It should be noted that the above embodiments are combined, and when turning,
At the start of turning operation, the control is made hard, at the time of steady turning state, the basic control (soft) is performed, and at the end of turning, the control is made soft when the roll angle is large, and hard when the roll angle becomes small. it can. An example of such control is shown in FIG.

(Effects of the Invention) As described above, according to the present invention, a high damping force is applied at the start of turning operation, and a low damping force is obtained at the end of turning operation when the vehicle body roll angle is equal to or more than the predetermined value. In this case, a high damping force is applied to prevent rolling progress during turning and prevent recoil (swing-back) during rolling restoration, while further reducing the rolling restoring time, thereby shortening the hard state time during rolling restoration. And shorten
It is possible to reduce the time during which the ride quality is poor.

[Brief description of the drawings]

FIG. 1 is a perspective view showing the overall structure of a suspension device according to the present invention, FIG. 2 is a block diagram of the suspension device of the first embodiment, and FIGS. 3A and 3B are dampers of the first, third and fourth embodiments. 4, FIG. 4 is a flowchart showing the basic control operation of the first and third embodiments, FIG. 5 is a flowchart showing the steering angular velocity calculating operation of the auxiliary control, and FIG. 6 is a flowchart of the first embodiment. FIG. 7 is a flowchart showing a rolling operation control operation of the auxiliary control, FIG. 7 is a diagram showing a vehicle body roll angle, FIG. 8 is a diagram showing an example of a control mode of the first and second embodiments, and FIGS. 9A and 9B. FIG. 10 is a partial sectional view showing a damper of the second embodiment, FIG. 10 is a block diagram of a suspension device of the second embodiment, FIG. 11 is a flowchart showing basic control operations of the second embodiment, and FIG. Flowchart showing control operation when rolling occurs in the embodiment , FIG. 13 is a flowchart showing a control operation at the time of occurrence of rolling of the third embodiment, FIG. 14 is a diagram showing an example of a control mode of the third and fourth embodiments, and FIG. 15 is a suspension device of the fourth embodiment. FIG. 16 is a flowchart showing a basic control operation of the fourth embodiment, and FIG.
FIG. 17 is a flowchart showing a control operation at the time of occurrence of rolling according to the fourth embodiment, and FIG. 18 is a diagram showing an example of a control mode when each embodiment is combined. 2a, 2b, 2c, 2d: damping force variable damper 20: damping force control means

Claims (2)

(57) [Claims] 1. A damping force variable damper capable of changing a damping force according to a driving state of a vehicle, a damping force of the damper being set to a high damping force at the start of a turning operation, a low damping force at a steady turning, and a turning end. In operation, damping force control means for setting a low damping force when the vehicle body roll angle is equal to or more than a predetermined value and a high damping force when the vehicle body roll angle is less than the predetermined value. Suspension equipment. 2. A damping force variable damper capable of changing a damping force according to a driving state of a vehicle, a damping force of the damper being set to a high damping force at the start of a turning operation, a high damping force at a steady turning, and a turning end. In operation, damping force control means for setting a low damping force when the vehicle body roll angle is equal to or more than a predetermined value and a high damping force when the vehicle body roll angle is less than the predetermined value. Suspension equipment.