JPH03217310A - Suspension device for vehicle - Google Patents

Abstract

PURPOSE:To effectively suppress the occurrence of the slip of a drive wheel during acceleration by effecting control such that the damping force of a damping force variable type damper mounted on each wheel is varied from a hard state to a soft state when the occurrence of the slip of the drive wheel is detected. CONSTITUTION:In a shock absorber serving as a damper mounted to each wheel, two orifices 63 and 64 are formed in a pinion unit 62 slidably engaged internally of a cylinder 61, and the orifice 64 can be opened and closed by means of an actuator 65. The actuator 65 is formed such that the orifice 64 is opened and closed by vertical movement of a control rod 67 by means of a magnet force generated by a solenoid 66 and the spring forces of springs 68a and 68b. Thus, a damping force is variable in two stages of a high and a low stage. The solenoid 66 effects control such that, during detection of the slip of a drive wheel, the damping force on the drive wheel of the shock absorber is switched from a hard state to a soft state by closing the orifice 64.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a suspension system for a vehicle, and particularly relates to a suspension system for a vehicle that is provided with a damper with variable damping force or a spring with variable spring constant corresponding to each wheel. .

(Prior Art) Generally, a suspension system for a vehicle is equipped with a shock absorber as a damper that damps the vertical motion of a wheel. These shock absorbers include those with variable damping force, in which the damping force or damping characteristics can be changed in two stages (refer to Japanese Utility Model Application Publication No. 109008/1983), and those with variable damping characteristics. There are those that can be changed, and those that have different damping characteristics for the shock absorber's compression operation (that is, compression damping characteristics) and those for its extension operation (that is, extension damping characteristics).

Among such variable damping force type shock absorbers, the following control method is known in particular when equipped with a shock absorber whose damping characteristics can be changed in two stages, high and low. In any of the control methods described below, the damping characteristics of the shock absorber are usually made soft (that is, low damping) in order to improve riding comfort.

■ To suppress squat during acceleration, the damping characteristics of the shock absorber are set to hard (hard) when acceleration is detected.
In other words, high attenuation) (USP. No. 4586728
reference).

■ In front-wheel drive vehicles, in order to prevent front wheels from slipping during sudden acceleration, when sudden acceleration is detected, the damping characteristics of the shock absorber on the front wheel, which is the driving wheel, are softened, and the shock absorber on the rear wheel, which is the driven wheel, is softened. (Refer to Japanese Unexamined Patent Publication No. 59-73313.) ■ In order to suppress rolling during turning, the damping characteristics of the shock absorber are made hard when the occurrence of a lateral load is detected, and the rolling Maintain the hard state for a certain period of time to prevent deterioration of maneuverability due to recoil when restoring (
(See Japanese Unexamined Patent Publication No. 151307/1983).

(Problems to be Solved by the Invention) However, in FR type vehicles, there is still nothing that can effectively suppress rear wheel slip during sudden acceleration. Here, as in the control method described in (1) above, even in an FR type car, when sudden acceleration is detected, the damping characteristics of the shock absorber on the rear wheel side, which is the driving wheel, are softened, and the damping characteristics of the shock absorber on the front wheel side, which is the driven wheel, are softened. It is possible to make the damping characteristics of
In this case, unlike in the case of FR type vehicles, it is generally not possible to implement this because it promotes the squat phenomenon during acceleration.

In addition, in both FF and FR models, shock absorbers with variable damping force or other dampers are used to prevent spin-outs due to skidding of the left and right rear wheels and drift-outs due to skidding of the left and right front wheels during sharp turns. There are still many things that can be effectively suppressed.

The present invention has been made in view of these points, and its purpose is to reduce the slippage of the driving wheels during acceleration,
Another object of the present invention is to provide a suspension device for a vehicle that can effectively suppress spin-out or drift-out during sharp turns.

(Means for Solving the Problems) In order to achieve the above object, the present invention basically uses a variable damping force damper (for example, a shock absorber) or a variable spring constant spring (for example, an air spring) to When the wheel slips or skids, the damper or spring on the wheel side is made soft.

The specific configuration of the present invention has two aspects corresponding to acceleration and turning, respectively.

The first aspect is for driving wheel slip during acceleration, and its specific configuration is as described in claim (1),
In a vehicle suspension system, which is provided with a variable damping force damper or a variable spring constant spring for each wheel, there is provided a slip detection means for detecting the slip of the drive wheel, and a slip detection means that receives a signal from the detection means and detects the slip of the drive wheel. The present invention is configured to include damping force/spring constant variable control means for changing and controlling a damper or a spring corresponding to a drive wheel at the time of slip from a hard state to a soft state.

Here, in order to suppress the drive wheel slip while suppressing the occurrence of squat, as described in claim (2), an acceleration detecting means for detecting the acceleration of the vehicle is further provided, and the damping force and spring constant are The variable control means receives the signal from the acceleration detection means together with the signal from the slip detection means, and puts all dampers or springs into a hard state during normal acceleration, and only puts the dampers or springs corresponding to the drive wheels into a hard state when the drive wheels slip. It is desirable to have a configuration that controls the switching from a hard state to a soft state.

The second aspect is to prevent wheel skidding when turning, and the specific configuration thereof is, as described in claim (3), a damper with variable damping force or a variable spring constant spring corresponding to each wheel. A suspension system for a vehicle comprising: skidding detection means for detecting skidding of front and rear wheels;
A lateral acceleration detection means detects lateral acceleration acting on the vehicle body, and signals from both of the above detection means are received, and when the lateral acceleration exceeds a predetermined value, all dampers or springs are put into a hard state, and one of the front wheels and the rear wheels is set to a hard state. The vehicle is configured to include damping force/spring constant variable control means for controlling only the damper or spring corresponding to the skidding wheel to change from a hard state to a soft state when one of the wheels skids.

(Function) With the above configuration, in the invention described in claim (1), when the drive wheels slip during acceleration of the vehicle, the slip detection means quickly detects this and also transmits a signal from the detection means. Under the control of the received damping force/spring constant variable control means, only the damping force variable damper or the spring constant variable spring corresponding to the drive wheel is changed from the hard state to the soft state. As a result, the vehicle body leans toward the drive wheels, and the vehicle body load acts biasedly toward the drive wheels, thereby increasing the ground contact load and suppressing slippage. Moreover, this tilting of the vehicle body toward the drive wheels does not always occur during acceleration, but only occurs when the drive wheels slip, so even in the case of FR type cars, it promotes squatting during acceleration. Never. In particular, claim (2)
In the case of the described invention, all variable damping force dampers or variable spring constant springs are held in a hard state during normal acceleration without drive wheel slip, so it is possible to suppress the occurrence of squat.

Further, in the invention described in claim (3), during normal turning, that is, when lateral acceleration acts on the vehicle body at a predetermined value or more, the lateral acceleration detection means detects this and receives a signal from the detection means. Based on the control of the variable damping force/spring constant control means, all variable damping force dampers or variable spring constant springs are put into a hard state, thereby suppressing rolling of the vehicle body. When either the front wheel or the rear wheel skids during a turn, the skid detection means quickly detects this and controls the damping force/spring constant variable control means that receives a signal from the detection means. Accordingly, only the variable damping force damper or the variable spring constant spring corresponding to the skidding wheel is changed from the soft state to the hard state.

As a result, the vehicle body leans toward the skidding wheels (front wheel side or rear wheel side), and the vehicle body load acts biasedly toward the front wheels or rear wheels, thereby increasing the ground contact load and suppressing skidding.

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

FIG. 1 shows a component layout of a suspension device according to a first embodiment of the present invention. This example demonstrates the invention
This is an example of application to a model car.

In FIG. 1, 1 to 4 are four shock absorbers provided corresponding to the left and right front wheels 5L (only the left front wheel is shown) and the rear wheel 6L (only the left rear wheel is shown), It is a type of damper that dampens the vertical movement of each wheel (that is, the force that acts between the vehicle body (sprung) and the axle (unsprung)). Each of the shock absorbers 1 to 4 has a built-in actuator 65 (see Fig. 2) that allows the damping characteristics or damping force to be changed to two levels, high and low, and also detects relative displacement between the vehicle body and the axle. It has a built-in vehicle height sensor (not shown). 7 is a control unit that outputs a control signal to the actuator in each of the shock absorbers 1 to 4 to variably control its damping characteristics; A detection signal is output from the vehicle height sensor.

Further, 11 to 14 are four acceleration sensors that detect the acceleration of the vehicle body in the vertical direction (Z direction), 15 is a vehicle speed sensor installed in the meter of the instrument panel that detects the vehicle speed, and 16 is the rotation of the steering shaft. A steering angle sensor 17 detects the steering angle of the front wheels, and an accelerator opening sensor 17 detects the accelerator opening.The accelerator opening sensor 17 detects the acceleration or acceleration time of the vehicle, which has a correlation with the accelerator opening. It has the function of detecting acceleration. 18 is a brake pressure switch that detects whether the brake is in operation (that is, whether braking is being performed) based on the brake fluid pressure; and 19 is a HARD. SOFT, CONTR
This is a mode selection switch that switches to any mode of OL, and these sensors 11 to 17 and switch 18
, 19 are all output to the control unit 7. Although not shown, a wheel rotation speed sensor for detecting the rotation speed of each wheel is provided in the brake unit of each wheel, and a detection signal from this sensor is also output to the control unit 7.

Fig. 2 shows the structure of the main parts of the shock absorbers 1 to 4, Fig. 2A shows the damping characteristics of the shock absorbers 1 to 4 when they are in the HARD state, and Fig. 2B shows the damping characteristics of the shock absorbers 1 to 4 when they are in the HARD state. Indicates the SOFT state. Note that vehicle height sensors built into the shock absorbers 1 to 4 are omitted in this figure.

In FIG. 2, 61 is a cylinder, and a piston unit 62 formed by integrally molding a piston and a piston rod is slidably inserted into the cylinder 61. The cylinder 61 and piston unit 62 are
They are connected to the axle (unsprung) or the vehicle body (sprung) via separately provided connection structures (not shown).

The piston unit 62 has two orifices 63.
64 are provided. One of the orifices 6
3 is always open. Further, the other orifice 64 is provided so as to be openable and closable by an actuator 65. The actuator 65 includes a solenoid 66 and a control rod 6.
7 and two springs 68a and 68b. The control rod 67 is configured to move up and down within the piston unit 62 by the magnetic force received from the solenoid 66 and the urging force received from both springs 68a and 68b, thereby opening and closing the orifice 64.

The upper chamber 69 and lower chamber 70 in the cylinder 61 and the cavity in the piston unit 62 communicating with this compartment 69,70 are filled with a fluid of appropriate viscosity. This fluid can move between the upper chamber 69 and the lower chamber 70 through either of the orifices 63, 64.

In the above configuration, the shock absorbers 1 to 4 perform the following operations.

That is, when the solenoid 66 is not energized, the force of the spring 68a that biases the control rod 67 downward is set to be stronger than the force of the spring 68b that biases the control rod 67 upward. 67 is pressed downward and closes the orifice 64. Therefore, the fluid passage is only through the orifice 63, and the damping characteristics of the shock absorbers 1 to 4 are in a HARD (high damping) state.

Further, when the solenoid 66 is energized, the control rod 67 is pulled upward by the magnetic force of the solenoid 66, and the orifice 64 is opened. For this reason, both orifices 63
．． Both 64 serve as fluid passages, and the shock absorber 1
The damping characteristic of ~4 is a SOFT (low damping) state.

As mentioned above, the shock absorbers 1 to 4 are in the HARD state when the solenoid 66 is de-energized.
Even if the control unit 7 should fail, the shock absorbers 1 to 4 can maintain the HARD state and prevent deterioration of steering stability.

FIG. 3 shows a block configuration of the control section of the suspension device. In FIG. 3, a first vehicle height sensor 41, an acceleration sensor 11, a wheel rotation speed sensor 31, and an actuator 65
a is attached to the front wheel 5L on the left side of the vehicle; the second vehicle height sensor 42, acceleration sensor 12, wheel rotation speed sensor 32, and actuator 65b are attached to the front wheel on the right side of the vehicle; The rotational speed sensor 33 and the actuator 65c correspond to the rear wheel 6L on the left side of the vehicle, and the fourth vehicle height sensor 44, the acceleration sensor 14, the wheel rotational speed sensor 34, and the actuator 65d correspond to the rear wheel on the right side of the vehicle. Furthermore, the actuator 65a
65d is the same as the actuator 65 in FIG.
-44 are built in shock absorbers 1-4.

Further, r1 to r4 are the first to fourth vehicle height sensors 4, respectively.
1 to 44 toward the control unit 7, and all of these signals take continuous values. This signal is the shock absorber 1
When ~4 expands, it is positive, and when it contracts, it is negative. still,
The relative displacement when the vehicle is stationary is assumed to be zero, and the deviation from this represents the magnitude of the relative displacement.

2e+ to 2G4 are the first to fourth acceleration sensors 1, respectively.
These are vehicle body absolute acceleration signals in the vertical direction (Z direction) outputted from 1 to 14 toward the control unit 7, and all of these signals take continuous values. This signal is positive when the vehicle body receives upward acceleration, and negative when the vehicle body receives downward acceleration.

ω1 to ω4 are the first to fourth wheel rotation speed sensors 3, respectively.
1 to 34 toward the control unit 7, and all of these signals take continuous values. This signal is positive when the wheels rotate in the forward direction of the vehicle, and negative when the wheels rotate in the opposite direction.

In addition, the vehicle speed sensor 15 outputs a vehicle speed signal, the steering angle sensor 16 outputs a steering angle signal, and the accelerator opening sensor 17 outputs an accelerator opening signal to the control unit 7. Both take continuous values. The vehicle speed signal is positive when the vehicle is moving forward, and negative when the vehicle is moving backward. As seen from the driver's side, the steering angle signal is positive when the steering wheel rotates counterclockwise (i.e., when turning left), and negative when it rotates clockwise (i.e., when turning right). .

Further, a brake pressure signal is outputted from the brake pressure switch 18 to the control unit 7, and this signal has two values, ON and OFF. ON means that the brake is being operated, and OFF means that it is not.

■1 to v4 are actuator control signals output from the control unit 7 to the first to fourth actuators 65a to 65d, respectively, and these signals v
1 to v4 take two values of "1" and "0". When the value is "1", the actuator solenoid 66 (see FIG. 2) is not energized, and the damping characteristics of the shock absorbers 1 to 4 are in the HARD state. Also, when the value is "0", the solenoid 66 of the actuator is energized, and the shock absorber 1
The damping characteristic of ~4 is in a SOFT state.

Furthermore, a mode selection signal is outputted from the mode selection switch 19 toward the control unit 7, and this signal is a plurality of parallel signals, and in the case of this embodiment, a mode selection signal is outputted to the control unit 7.
, SOFT, CONTROL. HARD indicates that the driver has selected HARD mode.
CONTR T indicates that SOFT mode is selected.
OL means that the CONTROL mode is selected. As will be described later, in HARD, the damping characteristics of all shock absorbers 1 to 4 are fixed to the HARD state, and in SOFT, all shock absorbers 1 to 4 are fixed to the HARD state.
The damping characteristics of CONTROL are fixed to the SOFT state and
At this time, the damping characteristics of each of the shock absorbers 1 to 4 are automatically switched to the HARD or SOFT state depending on the driving and operating conditions of the vehicle.

FIG. 4 shows the basic control flow of the control unit 7. This control operation is executed by a control program installed in the control unit 7. This control program is repeatedly activated at a constant cycle (1 to 10 ms) by a separately provided activation program. In addition, “
The "normal control flag" is a virtual switch placed in the memory or the like in the control unit 7, and takes two values: ON and OFF. The normal control flag is set to O by a separately provided initialization program when the control unit 7 starts operating.
Initialized to N. This control operation will be explained below along the flow.

First, in step S2L, it is determined whether the normal control flag is ON. When the normal control flag is No, which is set to OFF for some reason, the operation is ended without performing the following control.

When the determination in step S21 is YES, step S
At step 22, it is determined whether the mode selection signal is HARD. If this determination is YES (HARD), all of the actuator control signals v1 to ■4 are set to 1 in step S32.
In step S31, lever control signals v1 to ■4 are set.
Output. As a result, all shock absorbers 1
A damping characteristic of ~4 is a HARD state. In this case, the operation ends.

When the value of the mode selection signal is not HARD, it is then determined in step S23 whether the value of the mode selection signal is SOFT, and when the determination is YES (SOFT), the actuator control signal is ■1～
All of v4 are set to 0, and the control signals (1) to (4) are output in step S31. As a result, the damping characteristics of all the shock absorbers 1 to 4 are brought into the SOFT state.

In this case, the operation ends.

Both the judgments in steps S22 and S23 above are NO.
, that is, when the value of the mode selection signal is CONTROL, the relative displacement signal r between the vehicle body axles is determined in step S24.
After inputting 1 to r4, in step S25 these r1 to r
4 is differentiated using a numerical differential method or the like to obtain the relative speeds t1 to t4 between the vehicle body axles. Next, in step 32B, after inputting the vertical vehicle body absolute acceleration signals 2c+ to iG4,
Step S27: Integrate levers 2G1 to 2G4 using numerical integration method or the like, and calculate the vertical vehicle absolute speed ic. +~2e
Find 4. Since these 2G1 to 2G4 are the absolute velocity of the vehicle body in the vertical direction at the acceleration sensor position, step 828
Then, this is converted into vertical vehicle absolute speeds 2s+ to 2s4 at the positions of each shock absorber 1 to 4. s1
Since s4 can be found if three of C, I and G4 are known, 2GI to ic3 will be used below, and ic4 will be a preliminary value. Here, when the origin is appropriately set in the horizontal plane and the xy coordinates are taken (see Figure 1), the coordinates of the acceleration sensors 11 to 13 are (xc+, y
G+ ) ~ (xc3, yc3), and the coordinates of shock absorbers 1 to 4 are (xs+ rys+ ) - (x
s4, YS4), 2c+ ~zC. 4 is obtained by the following formula.

However, the two coefficient matrices and their product are calculated in advance,
It is given as a constant.

Subsequently, in step 529, the determination functions h1 to h are determined using the following equations.
Find 4.

hi-ii ・2si (i-1.2, 3.4) Then, in step S30, the actuator control signal v1
~Determine the value of v4. The values of the control signals v1 to V4 are set to Vi-1 if the judgment function IN for each shock absorber 1 to 4 is zero or positive (hi≧0), and if the judgment function hf is negative (hi <0) then vi
-0.

After this setting, the actuator control signals v1 to v4 are output in step S31, and the operation ends.

According to the basic control described above, when the driver controls
If L mode is selected, each shock absorber 1
The damping characteristics of ~4 are determined when the judgment function hi is positive at that position (that is, when the absolute vehicle velocity in the vertical direction is a positive upward speed and the shock absorber is in an extended state, or when the absolute vehicle velocity in the vertical direction is negative). HAR at downward speed and when the shock absorber is in compression mode)
When state D is entered and the judgment function h1 is negative (that is, when the absolute vehicle body speed in the vertical direction is a downward speed and the shock absorber is in an extension operation state, or when the absolute vehicle body speed in the vertical direction is an upward speed and the shock absorber is in a compression action state) ), it enters the SOFT state. This appropriately suppresses both the phenomenon in which high-frequency vibrations input from the road surface to the unsprung area are transmitted to the unsprung top, and the phenomenon in which low-frequency vibrations input from the road surface to the unsprung area excites resonance on the spring. , it is possible to realize a good ride comfort without a lumpy or squishy feeling.

5 and 6 show the auxiliary control flow of the control unit 7. FIG. This control operation is performed by two programs installed in the control unit 7 together with the basic control program (a program corresponding to the rear wheel slip ratio calculation flow shown in FIG. 5 and a program corresponding to the rear wheel slip control flow shown in FIG. 6). program). These programs, like the basic control program, are repeatedly activated at fixed intervals (1 to 10 ms) by a separately provided activation program. This control operation will be explained below along the flow.

In the rear wheel slip ratio calculation flow shown in FIG. 5, first, in step S41, the first and second wheel rotation speed sensors 31
．． The wheel rotational speed signals ωl and ω2 from 32 are input, and in step S42, the average value is determined as the rotational speed ωF of the front wheel, which is the driven wheel.
shall be. Subsequently, in step 343, wheel rotation speed signals ω3,
ω4 is input, and in step S44, the average value is set as the rotational speed ωR of the rear wheel, which is the driving wheel. Then, in step S45, the slip ratio (slip ratio) SR of the rear wheels is determined using the following equation.

SR-(ωR - ωF)/ωF The calculated value of the rear wheel slip ratio SR is stored in the memory within the control unit 7. Also, a slip detection means 51 detects slip of the rear wheels (driving wheels) using the wheel rotation speed sensors 31 to 34 and steps 541 to S45.
is configured.

Thereafter, the flow shifts to the rear wheel slip control flow shown in FIG. In this control flow, first, step S
After inputting a steering angle signal in step S51, it is determined in step S52 whether the absolute value of the steering angle is smaller than a positive constant value θ0. When this judgment is NO and the steering angle is large (that is, when turning)
In step S60, the normal control flag is turned on to end the operation.

By turning on the normal control flag, the basic control described above becomes effective.

On the other hand, when the determination in step S52 is YES, indicating a small steering angle (that is, when not turning), an accelerator opening signal is input in step S53, and then, in step S54, the accelerator opening is determined to be equal to or greater than a certain value aO. In other words, it is determined whether or not the vehicle is accelerating. If this determination is NO, indicating that it is not acceleration, the normal control flag is turned ON in step S60 and the operation ends, as in the case of turning, while if the determination is YES, that it is accelerating, the normal control flag is turned OFF in step S55. do. This makes basic control invalid.

Subsequently, in step 85B, the rear wheel slip ratio SR is set to a predetermined value SR.
It is determined whether or not it is greater than or equal to O, and when this determination is YES, that is, when the rear wheel slip is excessive, step S5
Shock absorber 1 corresponding to the left and right front wheels respectively at 7,
The actuator control signal is set to vl, V2=1, in order to set the damping characteristics of shock absorbers 3 and 4 corresponding to the left and right rear wheels to the SOFT state.
Let v3, v4=0. On the other hand, if the determination is NO, that is, during normal acceleration where rear wheel slip is not excessive, actuator control is performed in step 558 to bring the damping characteristics of the four shock absorbers 1 to 4 corresponding to the front and rear wheels into the HARD state. Let the signal be vl~■4-1. After setting the actuator control signals vl-v4 in either step S57 or 55g, the control signals v1-v4 are outputted in step S59, and the operation ends. Through the above steps S56 to S59, all the shock absorbers 1 to 4 are set to the HARD state during normal acceleration, and only the shock absorbers 3 and 4 corresponding to the rear wheels are changed from the HARD state to the SOFT state when the rear wheels, which are driving wheels, slip. A damping force variable control means 52 is configured to control the damping force to be changed to .

Therefore, according to such auxiliary control, during normal acceleration when the rear wheels, which are the driving wheels, are not slipping, the damping characteristics of all shock absorbers 1 to 4 are in the HARD state (high damping), so that the damping characteristics during acceleration are It is possible to suppress squat (a phenomenon in which the rear vehicle body sinks).

On the other hand, when the rear wheels slip due to sudden acceleration, the damping characteristics of the shock absorbers 3 and 4 corresponding to the rear wheels become HA.
When the RD state is changed to the SOFT state, and the damping characteristics of the shock absorbers 1 and 2 corresponding to the front wheels are maintained in the HARD state, the vehicle body leans toward the rear wheels, which are slip wheels, and the vehicle body load is transferred to the rear wheels. Because it acts unevenly,
The ground contact load increases and slips can be suppressed.

Moreover, since the auxiliary control is repeatedly performed at short intervals (1 to 10 ms), the damping characteristics of each of the shock absorbers 1 to 4 can be finely switched. Therefore, unlike when the damping characteristics are fixed, the inconvenience that the vehicle body load is not applied to the shock absorber and the ground load decreases does not occur, and the ground load of the slipping wheel can be effectively increased.

It should be noted that the above-mentioned auxiliary control is effective only for rear-wheel drive vehicles such as FR type vehicles as in this embodiment.

7 and 8 show a modification of the auxiliary control flow of the control unit as a second embodiment of the present invention. This control operation is carried out by two programs (a program corresponding to each wheel slip ratio calculation flow shown in FIG. 7 and a program shown in FIG. 6) installed in the control unit 7 (see FIGS. 1 and 3) together with the basic control program. This program is executed by the program corresponding to the front/rear wheel skidding control flow shown in FIG. These programs, like the basic control program, are repeatedly activated at fixed intervals (1 to 10 ms) by a separately provided activation program. This control operation will be explained below along the flow.

In the flow of calculating each wheel slip ratio shown in FIG. 7, first,
In step S71, the vehicle speed signal from the vehicle speed sensor 15 is input, and in step S72, the standard wheel rotation speed ω0 is determined from the vehicle speed.
Estimate. Subsequently, in step S73, the actual wheel rotation speed signals ω1 to ω4 from the respective wheel rotation speed sensors 31 to 34 are
is input, and in step S74, the slip ratios (slip ratios) Sl to S4 of each wheel are determined from the following equations.

si − (ωI−ω0)/ω0 (i−1.2, 3.4) The calculated value of the slip ratio SL-84 of each wheel is stored in the memory within the control unit 7.

Thereafter, the flow shifts to the front/rear wheel skidding control flow shown in FIG. 8. In this control flow, first, in step S81, the steering angle signal from the steering angle sensor 16 is input, and in step S82, the vehicle speed signal from the vehicle speed sensor 15 is input, and then in step 883, the vehicle body is The lateral acceleration αy acting on the lateral acceleration αy is estimated, and in step S84 it is determined whether the absolute value of the lateral acceleration αy is larger than a positive constant value αyO. Here, since the lateral acceleration αy occurs as the vehicle turns, determining whether the absolute value of the lateral acceleration αy is larger than the positive constant value αyO is as follows:
This means that it is determined whether or not the vehicle is turning. In addition, the above-mentioned steps S81 to S84 and related sensors, that is, the steering angle sensor 16 and the vehicle speed sensor 1
5 constitutes a lateral acceleration detection means 61 for detecting lateral acceleration acting on the vehicle body, and this lateral acceleration detection means 61 has a function as a detection means for detecting when the vehicle is turning.

When the determination in step S84 is NO, that is, when the lateral acceleration αy is small and the vehicle is not turning, the normal control flag is turned on in step S8B and the operation is ended. By turning on the normal control flag, the basic control shown in FIG. 4 becomes effective. On the other hand, step S8
When the determination in step S85 is YES, that is, when the vehicle is turning with a large lateral acceleration αy, the normal control flag is turned OFF at step S85. This makes basic control invalid.

Subsequently, in steps 587 to 598, the flag F1
The value of ~F4 is determined as follows.

That is, the absolute value of the slip ratio 81 to S4 of each wheel (lsi
When l) is greater than or equal to the positive constant value SiO, a flag Fl-1 is set, and when the absolute value (lsil) of the slip ratios 81 to S4 of each wheel is smaller than the positive constant value SiO, a flag Fi-0 is set. Here, the flag F1 is its number i (i-1.2
, 3.4) is used to remember whether or not the slip ratio of the wheel specified in , and a value of 0 indicates that the slip ratio of the wheel is small.

Subsequently, in step S99, the value of the flag FP is set to the flag F1.
and F2 (FlxF2), and the value of flag FR is calculated as the logical product (F3 x F4) of flags F3 and F4.
). Here, the flags FF and FR are used to remember whether or not the left and right wheels are skidding at the same time; a value of 1 indicates skidding, and a value of 0 indicates skidding. The time indicates that there is no skidding.

Therefore, for example, when the value of FF is 1, it means that the left and right front wheels are simultaneously skidding, that is, drift out, and when the FR value is 1, it means that the left and right rear wheels are simultaneously skidding, that is, the wheels are spinning. This means that an out has occurred. In addition, the steps related to the calculation of the flags FF and FR (step S71- in the wheel slip ratio calculation flow) are also performed.
574 and step 38 in the control flow when front and rear wheels skid
7 to S99) and sensors (vehicle speed sensor 15 and wheel rotation speed sensors 31 to 34) constitute a sideslip detection means 62 that detects sideslip of the front wheels and rear wheels.

Subsequently, in steps S100 to S105, flags FP, Fl? The values of actuator control signals (1) to (4) are set according to the combination of values. That is, ■ When the FP value and the FR value are both 0 (that is, neither the front wheels nor the rear wheels are skidding), or when the FF value and the FR value are both 1 (that is, when the FF value and the FR value are both 1) Before·
(when both rear wheels are skidding), step S1
03 sets the damping characteristics of all shock absorbers 1 to 4 to H.
Actuator control signals V1 to V4 to enter the ARD state
Set all values to l.

■ When the value of FP is 1 and the value of FR is 0 (that is, when the front wheels are skidding and drift-out has occurred), in step S104, the shock absorber 1 corresponding to the front wheels is
, 2 to the SOFT state and the damping characteristics of the shock absorbers 3 and 4 corresponding to the rear wheels to the HARD state.
, v4-1.

■ When the FFO value is 0 and the FR value is 1 (that is, when the rear wheels are skidding and a spinout has occurred), in step S105, the shock absorber 1 corresponding to the front wheels is
, 2 to the HARD state and the damping characteristics of the shock absorbers 3 and 4 corresponding to the rear wheels to the SOFT state.
The score will be 4-0.

After setting the values of the actuator control signals v1 to 4 in any of steps 3 103 to S 105, the actuator control signals v1 to 4 are set in step 8106.
1 to v4 are output and the operation ends.

Through the above steps 8100 to 8106, all shock absorbers 1 to 4 are set to the HARD state when the lateral acceleration is greater than a predetermined value (that is, when the vehicle is turning), and when either the front wheels or the rear wheels skid. A damping force variable control means 63 is configured to control only the shock absorber corresponding to the skidding wheel to change from the HARD state to the SOFT state.

Therefore, according to such auxiliary control, during a normal turn when neither the front wheels nor the rear wheels are skidding,
The damping characteristics of all shock absorbers 1 to 4 are HARD.
(high damping), rolling of the vehicle body can be suppressed.

On the other hand, when the front wheels skid due to sudden turns, etc., the damping characteristics of the shock absorber corresponding to the front wheels], 2 are changed to HA.
When the RD state is changed to the SOFT state, and the damping characteristics of the shock absorbers 3 and 4 corresponding to the rear wheels are maintained in the HARD state, the vehicle body leans toward the front wheels, which are skidding wheels, and the vehicle body load is biased toward the front wheels. This increases the ground contact load and suppresses skidding.

Also, when the rear wheels skid, only the damping characteristics of the shock absorbers 3 and 4 corresponding to the rear wheels will be HARD.
The state is changed from the SOFT state to the SOFT state, the vehicle body is tilted toward the rear wheels, and the vehicle body load is biased toward the rear wheels, so that the ground contact load increases and skidding can be suppressed.

In addition, when both the front wheels and rear wheels skid, the damping characteristics of all shock absorbers 1 to 4 are changed to HA, as in normal turning when neither the front wheels nor the rear wheels skid.
The purpose of setting the vehicle in the RD state is to maintain the balance of the vehicle weight and ensure maneuverability. Also, in this embodiment, the auxiliary control is carried out in short cycles (1 to
10 mS), and the damping characteristics of each shock absorber 1 to 4 are finely switched, so that the ground load of the slipping wheel can be effectively increased.

The above auxiliary control can be applied to both FF and FR vehicles.

It should be noted that the present invention is not limited to the first and second embodiments described above, but includes various other modifications. For example, in the first embodiment, the acceleration detecting means for detecting the acceleration of the vehicle is formed by the accelerator opening sensor 17 for detecting the accelerator opening. , a sensor that detects acceleration in the longitudinal direction of the vehicle body may be used. Also, the second
In the embodiment, in the control unit 7, the lateral acceleration of the vehicle body was determined based on the steering angle signal from the steering angle sensor 16 and the vehicle speed signal from the vehicle speed sensor 15. It may also be detected.

Furthermore, in each of the above embodiments, the present invention is applied to a vehicle suspension device that is equipped with a shock absorber as a variable damping force damper corresponding to each wheel, but instead of this shock absorber. Of course, the present invention can also be similarly applied to vehicle suspension systems equipped with other variable damping force dampers or variable spring constant springs such as air springs.

(Effects of the Invention) As described above, according to the invention described in claim (1), when the driving wheels slip during acceleration of the vehicle, only the variable damping force type damper or the variable spring constant spring corresponding to the driving wheels is used. By changing from the hard state to the soft state, the vehicle body leans toward the drive wheels, and the vehicle body load acts biasedly toward the drive wheels, which increases the ground contact load and suppresses slipping, making it possible to control the vehicle. Safety can be improved.

Moreover, the tilt of the vehicle body toward the drive wheels does not always occur during acceleration, but only occurs when the drive wheels slip, so even in the case of an FR type vehicle, it does not promote squat during acceleration. .

In particular, in the case of the invention set forth in claim (2), all variable damping force dampers or variable spring constant springs are held in the /'% state during normal acceleration without drive wheel slip.・It is possible to suppress the occurrence of

In addition, in the invention described in claim (3), during normal turning, all variable damping force dampers or variable spring constant springs are put in a hard state to suppress rolling of the vehicle body.
When either the front or rear wheels skids during a turn, only the variable damping force damper or variable spring constant spring corresponding to the skidding wheel is changed from a soft state to a nodal state. Since the vehicle body leans toward the skidding wheels and the vehicle body load acts biased toward the front or rear wheels, the ground load increases, suppressing skidding of the front and rear wheels and the resulting drift-outs and spin-outs. This makes it possible to improve maneuverability.

[Brief explanation of drawings]

The drawings show embodiments of the present invention, and are shown in FIGS. 1 to 6.
The drawings show the first embodiment, FIG. 1 is a perspective view showing the layout of parts of the suspension device, FIG. 2 is a vertical side view of the main parts of the shock absorber, and FIG. 3 is a block configuration diagram of the control section of the suspension device. , FIG. 4 is a flowchart of the basic control, FIG. 5 is a flowchart showing the rear wheel slip ratio calculation flow of the auxiliary control, and FIG. 6 is a flowchart of the rear wheel slip control flow of the auxiliary control. 7 and 8 show the second embodiment, and FIG. 7 is a flowchart showing the calculation flow of each wheel slip ratio of auxiliary control,
FIG. 8 is a flowchart showing the control flow of the auxiliary control when the front and rear wheels skid. 1 to 4...Shock absorber 5L...Front wheel 6L...Rear wheel 7...Control unit 17...Accelerator opening sensor (detection means during acceleration) 51
... Slip detection means 52, 63 ... Damping force variable control means 61 ... Lateral acceleration detection means 62 ... Skid detection means 1 to 4 Shock absorber 5L Front wheel 17 ... Accelerator opening sensor ( Acceleration detection means) 51
Slip detection means 52, 63... Damping force variable control means 61... Lateral acceleration detection means 62, sideslip detection means 5L Fig. 1 Fig. 2A Fig. 2B Fig. 4 Fig. 5 Fig. 7

Claims (3)

[Claims] (1) In a suspension system for a vehicle, which is provided with a variable damping force damper or a variable spring constant spring corresponding to each wheel, a slip detection means for detecting slip of a driving wheel, and receiving a signal from the detection means, 1. A suspension device for a vehicle, comprising a damping force/spring constant variable control means for controlling a damper or a spring corresponding to a drive wheel to change from a hard state to a soft state when the drive wheel slips. (2) In a suspension system for a vehicle, which includes a variable damping force damper or a variable spring constant spring corresponding to each wheel, a slip detection means detects slip of the drive wheel, and an acceleration time detecting means detects when the vehicle accelerates. Upon receiving signals from the detection means and both of the detection means, all dampers or springs are set to a hard state during normal acceleration, and only the damper or spring corresponding to the drive wheel is changed from a hard state to a soft state when a drive wheel slips. 1. A suspension device for a vehicle, comprising variable damping force/spring constant control means. (3) In a vehicle suspension system that is equipped with a damper with a variable damping force or a spring with a variable spring constant corresponding to each wheel, a skid detection means that detects skidding of the front and rear wheels and a skid detection means that detects skidding of the front and rear wheels and detects lateral acceleration acting on the vehicle body. A lateral acceleration detection means detects the lateral acceleration, and when the lateral acceleration is above a predetermined value, all dampers or springs are put into a hard state by receiving signals from both of the above-mentioned detection means, and when either the front wheels or the rear wheels skid. A suspension device for a vehicle, comprising a damping force/spring constant variable control means for controlling only a damper or a spring corresponding to a skidding wheel to change from a hard state to a soft state.