JP3148401B2 - Vehicle suspension system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a suspension system for a vehicle for optimally controlling a damping force characteristic (hard or soft, etc.) of a shock absorber, and more particularly to a control for a roll of the vehicle.

[0002]

2. Description of the Related Art Conventionally, as a vehicle suspension system for controlling damping force characteristics of a shock absorber, for example, Japanese Patent Application Laid-Open No.
The one described in -163011 is known.

[0003] This conventional vehicle suspension detects the sprung vertical speed and the relative speed between the sprung and unsprung states. When both have the same sign, the damping force characteristic is set to a hard characteristic. Control of damping force characteristics based on the Skyhook theory, such as making the damping force characteristics soft, is performed independently for four wheels. Thus, the vibration damping energy can be increased with respect to the vibration energy transmitted to the vehicle body, and the vibration of the vehicle body can be suppressed, so that excellent ride comfort can be obtained. And the steering stability can be improved.

[0004]

However, in the above-described conventional device, if a control gain is determined so as to secure vibration suppression while suppressing the transmission of vibration to a sprung with respect to a road surface input, it is difficult to perform such operations during steering. As described above, when an inertial force is applied to the sprung to generate a roll, there is a problem that the control force is insufficient for the inertial force and a sufficient sprung mass damping effect cannot be obtained.

The present invention has been made in view of the above-mentioned conventional problems. In a straight running state or a steady turning state, the inertial force is suppressed while suppressing the transmission of vibration to the sprung portion to secure the vibration suppression. It is intended that sufficient control force be obtained when a roll occurs in addition.

[0006]

Therefore, in the present invention, the damping force characteristic of each suspension unit is controlled by a control signal obtained by using the lateral acceleration on the spring and the rate of change of the acceleration, so that the spring constant of the suspension is determined. The above-described object is achieved by applying a damping force in a direction of increasing the damping force.

That is, the vehicle suspension system of the present invention is shown in FIG.
As shown in the claim correspondence diagram, a suspension unit b interposed between the sprung and unsprung portions of the vehicle and capable of changing the damping force characteristic by the damping characteristic changing means a,
Input means e having up-down behavior detecting means c for detecting a factor relating to up-down behavior on the spring, and left-right acceleration detecting means d for detecting the acceleration of the vehicle body in the left-right direction on the spring.
And a control signal obtained using the lateral acceleration and the change rate of the lateral acceleration obtained from the signal from the lateral acceleration detecting means d and the signal obtained from the vertical behavior detecting means c. a damping force characteristic control means f for controlling the damping force characteristics, in the vehicle suspension system equipped with a
To change the damping characteristics of the suspension unit.
The step is fixed so that both the extension side and the compression side have the minimum damping characteristics.
Low damping, and the pressure side has a low attenuation approximately equal to that of the soft characteristic.
The attenuation characteristic on the extension side is fixed from the low attenuation characteristic
Extension side hardware characteristics continuously variable up to the maximum damping force characteristics
The extension side is fixed to a low attenuation characteristic substantially equal to that of the soft characteristic.
The attenuation characteristics on the compression side are reduced from the low attenuation characteristics to the maximum attenuation while being fixed.
Pressure-side hardware characteristics that are continuously variable up to the force characteristics.
And the damping force characteristic controlling means.
The step is based on the lateral acceleration and the rate of change of lateral acceleration.
It is determined whether the steering condition is satisfied or not.
Is controlled by the signal obtained from the vertical movement detection means.
A signal is formed, and when the steering conditions are satisfied, the lateral acceleration and
Control by the signal obtained based on the rate of change of the lateral acceleration
Forming a control signal, and based on the control signal,
Suspension unit when the threshold is exceeded at
Control to the extension side hard characteristic and according to the magnitude of the control signal
The damping force characteristic on the extension side is continuously changed, and the control signal
・ Control to soft characteristics when within negative threshold, control signal
Is smaller than the negative threshold,
Pressure damping force characteristics continuously according to the magnitude of the control signal.
It is characterized in that it is configured to change to
The invention according to claim 1 is as described in claim 2.
In the above, the damping force characteristic control means f
When judging the presence or absence of standing, the left and right acceleration (G)
The value multiplied by the acceleration change rate (△ G) is a preset value
If it is determined that the steering condition is satisfied when it is larger than (K) ,
If it is smaller, it is determined that the steering condition is not satisfied.
Wheel control signal is VFR, left front wheel control signal is VFL, right
The control signal for the rear wheel is VRR, the control signal for the left rear wheel is VRL,
The sprung vertical speed of the right front wheel is v1, the sprung vertical speed of the left front wheel
Degree v2, right rear wheel sprung vertical velocity v3, left rear wheel
Neural vertical speed v4, pitch rate VP, roll
Is VR, G is the lateral acceleration, and 左右 G is the rate of change of the lateral acceleration.
When you and, VFR = αf (v1 + βf v1 · vP + γf v1 · vR)
+ Af (ΔG + bf G) VFL = αf (v2 + βfv2 · vP−γfv2 · vR)
−af (ΔG + bf G) VRR = αr (v3−βrv3 · vP + γrv3 · vR)
+ Ar (ΔG + br G) VRL = αr (v4−βrv4 · vP−γrv4 · vR)
−ar (ΔG + br G) vP = (v1 + V2−v3−v4) / 2 vR = (v1 + V3−v2−v4) / 2 The control signal of each wheel is obtained by the formula (αf, α
r, βf, βr, γf, γr, af, and ar are coefficients.
You. ) And when the steering conditions are not satisfied, the coefficients af and ar are
0, and when the steering conditions are satisfied, the coefficients αf and αr are set to 0
You may do so.

[0008]

[0009]

[0010]

During running, a signal from vertical behavior detecting means for detecting a control factor indicating a vertical behavior on the sprung, such as a sprung vertical velocity or a sprung / unsprung relative velocity, and a lateral acceleration The damping force characteristic of each suspension unit is controlled by a control signal obtained by using the lateral acceleration obtained from the signal from the detecting means and the rate of change of the lateral acceleration.

Therefore, in the case of a roll such as when changing lanes or during a slalom, it is possible to perform control in accordance with the roll rate by using the rate of change of the lateral acceleration, and to correct the lateral acceleration by adding the lateral acceleration. The spring constant can be increased by applying the damping force in the direction of increasing the roll rigidity, and thereby the roll angle can be reduced.

[0012]

[0013] Ri per To perform the damping force characteristic control of the suspension unit as described above, as the extension side hard characteristic or the compression side hard characteristic, the case of controlling the one stroke direction in the high damping force characteristic, the opposite stroke side low attenuation Fixed to force characteristics. Therefore, for example, when the generated damping force is acting in the vibration direction, it is preferable to set the stroke direction to a low damping force characteristic. In this case, the reverse stroke side is controlled to a high damping force characteristic. Therefore, when the stroke direction of the suspension unit is switched to a state where the generated damping force acts in the vibration damping direction, there is no need to switch the characteristics of the suspension unit. As a result, high responsiveness is obtained, and the switching frequency is reduced to improve the durability.

[0014]

An embodiment of the present invention will be described with reference to the drawings. First, the configuration will be described.

FIG. 2 is a structural explanatory view showing a vehicle suspension system according to an embodiment of the present invention, wherein four shock absorbers (suspension units) are interposed between a vehicle body and four wheels. SA ₁ , SA ₂ , SA ₃ , SA
₄ (in describing the shock absorber, when referring to these four collectively, and when describing their common configuration, they are simply denoted by SA). A sprung vertical acceleration sensor (hereinafter, referred to as a vertical G sensor) 1 _FL , 1 for detecting a vertical acceleration is provided on the vehicle body near each shock absorber SA.
_FR , 1 _RL and 1 _RR are provided (note that these upper and lower G sensors are also simply referred to as upper and lower G sensors 1 when there is no need to specify the positions at which they are provided).

Then, among the four upper and lower G sensors 1,
As shown in FIG. 14, the components provided on the left and right sides of the front side of the vehicle body are attached so that the lower side in the acceleration detection direction gg is directed toward the vehicle center. Note that the inclination angle θ ₀ is set to an angle (for example, θ ₀ = 25 ° to 30 °) sufficiently larger than the roll angle (0 to 5 °) of the vehicle body.

The upper and lower Gs are located near the driver's seat.
A control unit 4 is provided for inputting a signal from the sensor 1 and outputting an operation signal to the pulse motor 3 of each shock absorber SA.

FIG. 3 is a system block diagram showing the above configuration. The control unit 4 includes an interface circuit 4a, a CPU 4b, and a drive circuit 4c. Is input.

The interface circuit 4a is provided with a circuit for processing a signal g obtained from each of the upper and lower G sensors 1. These circuits are shown in FIGS.
That is, FIG. 15 shows a low-pass filter LPF and a high-pass filter HPF for forming a signal indicating a sprung vertical speed (hereinafter, referred to as a vertical speed) v from a signal g obtained by each of the vertical G sensors 1. FIG.
Is a signal g obtained from the front upper and lower G sensors 1 _FL , 1 _FR
An arithmetic circuit 4e for calculating a difference, a high-pass filter HPF for differentiation, and a low-pass filter LPF for cutting high-frequency components for forming a signal indicating a lateral acceleration change rate ΔG from _FL and g _FR are shown. FIG. 17 also shows a signal g obtained from the front upper and lower G sensors 1 _FL and 1 _FR.
An arithmetic circuit 4e for calculating a difference, a high-pass filter HPF for preventing drift, and a low-pass filter LPF for cutting high-frequency components for forming a signal indicating the lateral acceleration G from _FL and g _FR are shown.

FIG. 4 is a sectional view showing the structure of the shock absorber SA.
A cylinder 30, a piston 31 defining the cylinder 30 in an upper chamber A and a lower chamber B, an outer cylinder 33 having a reservoir chamber 32 formed on the outer periphery of the cylinder 30, and a lower chamber B and a reservoir chamber 32 are defined. And a guide member 35 for guiding the sliding of the piston rod 7 connected to the piston 31, a suspension spring 36 interposed between the outer cylinder 33 and the vehicle body, and a bump rubber 37. In the drawing, reference numeral 7 denotes a piston rod, and a control rod 70 which is rotated by the pulse motor 3 is provided through the piston rod 7.

FIG. 5 is an enlarged sectional view showing a portion of the piston 31. As shown in FIG. 5, the piston 31 has through holes 31a and 31b formed therein, and An expansion damping valve 12 and a compression damping valve 20 for opening and closing 31a and 31b, respectively, are provided. A stud 38 penetrating the piston 31 is fixed to a bound stopper 41 screwed to the tip of the piston rod 7 by screwing.
Are provided with flow paths (extended second flow paths E, extended third flow paths F, bypass flow paths G, and pressure paths G, which will be described later) that connect the upper chamber A and the lower chamber B by bypassing the through holes 31a and 31b. A communication hole 39 for forming the second flow path J) is formed, and an adjuster 40 for changing the flow path cross-sectional area of the flow path is provided in the communication hole 39 so as to be rotatable. ing. Also, stud 3
An expansion side check valve 17 and a pressure side check valve 22 are provided on the outer peripheral portion of the expansion valve 8 to allow and block flow on the flow path side formed by the communication hole 39 in accordance with the flow direction of the fluid. The control rod 70 is connected to the adjuster 40. The stud 38 has a first port 21, a second port 13, a third port
A port 18, a fourth port 14, and a fifth port 16 are formed.

On the other hand, the adjuster 40 has a hollow portion 19, a first horizontal hole 24 and a second horizontal hole 25 communicating between the inside and the outside, and a vertical groove 23 formed in the outer peripheral portion. ing.

Therefore, between the upper chamber A and the lower chamber B, as a flow path through which fluid can flow during the extension stroke, the inside of the extension-side damping valve 12 is opened through the through hole 31b to open the lower chamber. B, the first port D on the extension side, the second port 13 and the flute 2
(3) a second expansion passage (E) that opens the outer peripheral side of the expansion damping valve (12) through the fourth port (14) to reach the lower chamber (B);
The extension side check valve 17 is opened via the port 13, the vertical groove 23, and the fifth port 16, and the extension side third valve reaching the lower chamber B is opened.
The flow path F, the third port 18, the second lateral hole 25, and the hollow portion 19
There are four flow paths of a bypass flow path G which leads to the lower chamber B via. Also, as a flow path through which fluid can flow in the pressure stroke,
The upper side chamber A is opened by opening the pressure side first flow path H passing through the through hole 31a and opening the pressure side damping valve 20, and opening the pressure side check valve 22 via the hollow portion 19, the first horizontal hole 24, and the first port 21. Pressure side second flow path J leading to the hollow portion 19, the second lateral hole 2
5, there are three flow paths: a bypass flow path G which reaches the upper chamber A via the third port 18.

That is, by rotating the adjuster 40, the characteristics of the shock absorber SA can be changed from a low damping force (soft) characteristic to a high damping force (hard) characteristic on both the extension side and the compression side. In the embodiment, since this characteristic change is configured to be changeable proportionally in multiple stages as shown in FIG. 6, this characteristic is expressed by the term attenuation coefficient.

Further, in this embodiment, as shown in FIG. 7, the adjuster 40 is rotated counterclockwise from a state where both the extension side and the compression side are soft (hereinafter referred to as soft characteristic SS). And, only the extension side can change the attenuation coefficient in multiple stages,
The compression side has a characteristic fixed to a low damping coefficient (hereinafter, referred to as the extension side hard characteristic HS). Conversely, when the adjuster 40 is rotated clockwise, the attenuation coefficient of only the compression side can be changed in multiple stages.
The expansion side is configured to have a region fixed to a low attenuation coefficient (hereinafter, referred to as a compression side hard characteristic SH).

Incidentally, in FIG. 7, when the adjuster 40 is disposed at the position of, KK of FIG.
The cross section, the LL section, the MM section, and the NN section are shown in FIGS. 8, 9, and 10, respectively, and the damping force characteristics at each position are shown in FIGS.

Next, the operation of the control unit 4 for controlling the driving of the pulse motor 3 will be described with reference to the flowchart of FIG. This control is performed separately for each shock absorber SA.

Step 101 is a step of reading the vertical velocity v, the lateral acceleration change rate ΔG, and the lateral acceleration G obtained by processing the signals from the vertical G sensors 1.

Step 102 is a step of determining whether or not a steering condition is satisfied, that is, a step of determining whether or not the absolute value of (G · ΔG) is larger than a predetermined value K. Proceed to step 103 and proceed to step 110 if NO. Incidentally, FIG. 19 shows a map of the steering condition satisfaction area (ON) and the non-satisfaction area (OFF). Incidentally, the steering condition is determined by providing a steering sensor and determining whether the absolute value of the product of the steering angle θ and the steering angular velocity Δθ is larger than a predetermined value (ON) or not (OF).
The determination may be made in F).

Step 103 is a step of performing processing for setting the flag F = 1.

Step 104 is a step for obtaining a control signal V for each shock absorber SA according to the following control equation. When this steering condition is satisfied (ON), the coefficient of the control equation is α _f = α _r = 0 and , A _f = a
_f , _ar = _ar .

[0032] _{(controlled) V FR = α f (v} 1 + β f v 1 · v P + γ f v 1 · v R) + a f (ΔG + b f G) V FL = α f (v 2 + β f v 2 · _{v P -γ f v 2 · v} R) -a f (ΔG + b f G) V RR = α r (v 3 -β r v 3 · v P + γ r v 3 · v R) + a r (ΔG + b r G) _{V RL = α r (v 4} -β r v 4 · v P -γ r v 4 · v R) -a r (ΔG + b r G) in addition, V _FR is the right front wheel, V _FL left front wheel, V _RR is Right rear wheel, V
_RL indicates a control signal for the left rear wheel. Hereinafter, when a specific signal is not indicated, it is simply referred to as a control signal V.

Where v ₁ is the sprung vertical speed of the right front wheel, v ₂ is the sprung vertical speed of the left front wheel, v ₃ is the sprung vertical speed of the right rear wheel, and v ₄ is the sprung vertical speed of the left rear wheel. Sprung vertical speed,
v _P is a pitch rate and v _R is a roll rate.

The pitch rate v _P is obtained from the difference between the front and rear average vertical velocities as shown in the following equation, and the roll rate v _R is obtained from the left and right average vertical velocities as shown in the following equation.

V _P = (v ₁ + V ₂ -v ₃ -v ₄ ) / 2 v _R = (v ₁ + V ₃ -v ₂ -v ₄ ) / 2 Next, step 105 is to calculate the control signal V In a step of determining whether or not the absolute value is larger than a predetermined threshold value δ, the process proceeds to step 106 with YES, and proceeds to step 1 with NO.
Proceed to 07.

Step 106 is a step for determining whether or not the control signal V is positive.
And proceeds to step 109 with NO.

Step 107 is the shock absorber S
This is a step of outputting an operation signal to the pulse motor 3 so as to control A to the soft characteristic SS.

In step 108, the shock absorber S
Pulse motor 3 so that A is controlled to the extension side hard characteristic HS.
Is a step of outputting an operation signal. The extension-side attenuation coefficient at this time is made proportional to the magnitude of the control signal V.

In step 109, the shock absorber S
Pulse motor 3 so that A is controlled to the compression side hard characteristic SH.
Is a step of outputting an operation signal. The compression damping coefficient at this time is made proportional to the magnitude of the control signal V.

Step 110 is a step for determining whether or not the flag F = 1. If YES, the routine proceeds to a step 111, and if NO, the routine proceeds to a step 114.

Step 111 is a step in which the timer is operated to start measuring the time t.

Step 112 is a step for determining whether or not the timer measurement time t has reached a predetermined time T _{0. If} YES, the process proceeds to step 113, and if NO, step 1 is performed.
Go to 04.

Step 113 is a step of performing a process for setting the flag F = 0.

In step 114, the steering condition is not satisfied (OF).
In the step of obtaining a control signal corresponding to the time F), in this case, the coefficients of the above control equation are set to α _f = α _f , α _r = α _r , and a _f = _ar = 0.

Next, the operation of the embodiment will be described.

A) When the Steering Condition is Not Satisfied When, for example, the vehicle is traveling straight ahead or at a constant turn (steady turn), the value of the product of the lateral acceleration G and the lateral acceleration change rate ΔG is small, and the steering condition shown in step 102 is satisfied. No (OFF).

In such a case, as in step 114, the coefficients of the control equation are α _f = α _f , α _r = α _r , and
As a _f = a _r = 0, to calculate the control signal V. In this case, the correction term for lateral acceleration becomes 0, the vertical velocity v, and controls the damping coefficient of the shock absorber SA based on the pitch rate v _P and roll rate v _R.

The operation state in this case is shown by a time chart of FIG. That is, this time chart
The control signal V (in this case, mainly the vertical speed v
), The damping force F, the relative speed between the sprung and unsprung states, the control direction of the shock absorber SA, and the operation signal (damping coefficient) output to the pulse motor 3.

As shown in this time chart, when the absolute value of the control signal V does not exceed the threshold value δ, the soft characteristic SS is controlled. When the absolute value of the control signal V exceeds the threshold value δ, the sign of the control signal V is changed. Is positive, the expansion-side hard characteristic HS is set. On the contrary, if the sign of the control signal is negative, the compression-side hard characteristic SH is set. Further, the attenuation coefficient is controlled in accordance with the magnitude of the control signal V. .

As described above, in this embodiment, the characteristics are switched based on the sign of the control signal V. However, as shown in the time chart, the control signal V and the relative speed substantially corresponding to the vertical speed v are used. In the state in which the sign of と coincides, that is, in the state in which the damping force generated in the shock absorber SA is acting in the vibration damping direction, the stroke direction is controlled to a high damping coefficient. In a state in which the sign of the control signal V and the sign of the relative speed match, that is, in a state in which the damping force is acting in the vibration direction, the stroke direction is controlled to a low damping coefficient (that is, the skyhook control is performed). T), and excellent ride quality can be obtained by suppressing road surface input.

Further, in the time chart, for example, as can be seen by referring to the case where the control direction of the first shock absorber SA is switched from the compression side software to the expansion side hardware, in controlling the compression side software,
If the control is switched to the extension-side hardware characteristic, it is not necessary to switch the damping force characteristic when switching the control direction of the shock absorber SA from the compression-side software to the extension-side hardware.
Therefore, it has a feature of being excellent in operation response and durability.

B) When the Steering Condition is Satisfied When changing lanes or during slalom, the value of the product of the lateral acceleration G and the lateral acceleration change rate ΔG increases, and the steering condition shown in step 102 is established (ON).

In such a case, as in step 104, the coefficients of the control equation are set to α _f = α _r = 0 and a _f = a
_The control signal V is calculated as _f , _ar = _ar . In this case, the term relating to the vertical velocity v becomes 0, and the damping coefficient of the shock absorber SA is controlled based on the lateral acceleration change rate ΔG and the lateral acceleration G.

The operating state in this case is shown by the time chart of FIG. The time chart includes, in order from the top, a lateral acceleration G and a lateral acceleration change rate ΔG, a control signal V when a steering condition is satisfied (control during steering), and a) a control signal when the steering condition is not satisfied (so-called skyhook control). V ′ is shown.

That is, when a roll occurs during steering such as when changing lanes or during slalom, the roll rate is determined based on the lateral acceleration change rate ΔG, and the lateral acceleration G is corrected. Therefore, by performing control using the control switching line at the time of steering shown in FIG. 22, the damping force is applied in a direction to improve the roll rigidity in accordance with the roll angle and the roll rate more accurately than in the skyhook control. Therefore, the roll angle can be reduced.

FIG. 23 shows the Lissajous waveform of the damping force in the case of the steering control according to the present embodiment by a solid line. As shown in FIG. 23, the spring constant can be increased. The roll angle can be reduced by the increase. In the drawing, the dotted line shows the case where the control signal V is made proportional only to the lateral acceleration change rate ΔG, and in this case, the spring constant does not change.

As described above, in this embodiment, during straight running or steady turning, the road surface input is suppressed so that vibration is suppressed and a good ride quality is obtained.
The damping force generated by the shock absorber SA is applied in the direction of increasing the roll rigidity so as to increase the spring constant, thereby suppressing the roll, thereby obtaining high steering stability.

Although the embodiment has been described above, the specific configuration is not limited to this embodiment, and any change in design or the like without departing from the gist of the present invention is included in the present invention.

For example, in the embodiment, the extension side hard characteristic H
S, compression side hardware SH, and an example of having a suspension unit capable of forming soft characteristic SS are shown. However, as shown in the prior art, a suspension unit in which the extension side and compression side simultaneously change from hardware to soft is used. May be used. In this case, it is necessary to detect the relative speed when performing the vibration suppression control.

The control formula for obtaining the control signal is not limited to the one shown in the embodiment, and the pitch rate and the roll rate may be omitted in the term of the speed v.

The suspension unit is not limited to the one shown in the embodiment as long as the damping force characteristic can be changed between hardware and software.

[0062]

As described above, in the vehicle suspension system of the present invention, the damping force characteristic control means includes a lateral acceleration and a change rate of the lateral acceleration obtained from a signal from the lateral acceleration detecting means, and a sprung mass. Since the damping force characteristic of each suspension unit is controlled by the control signal obtained using the signal obtained from the behavior detection means and the control signal obtained by using the By using the rate of change, control according to the roll rate can be performed, and by correcting the lateral acceleration, the generated damping force can be applied in the direction of increasing the roll rigidity to increase the spring constant. The effect that the roll angle can be reduced is obtained.

[0063]

[0064]

[Brief description of the drawings]

FIG. 1 is a conceptual view of a claim showing a vehicle suspension system of the present invention.

FIG. 2 is an explanatory diagram illustrating a configuration of a vehicle suspension device according to an embodiment of the present invention.

FIG. 3 is a system block diagram showing a vehicle suspension device according to the embodiment.

FIG. 4 is a cross-sectional view illustrating a shock absorber (suspension unit) applied to the embodiment device.

FIG. 5 is an enlarged sectional view showing a main part of the shock absorber.

FIG. 6 is a damping force characteristic diagram corresponding to a piston speed of the shock absorber.

FIG. 7 is a damping force characteristic diagram corresponding to a step position of a pulse motor of the shock absorber.

FIG. 8 is a perspective view of the shock absorber shown in FIG.
It is -K sectional drawing.

FIG. 9 is a perspective view of the shock absorber shown in FIG.
It is an L sectional view and MM sectional view.

FIG. 10 is a sectional view taken along line NN of FIG. 5 showing a main part of the shock absorber.

FIG. 11 is a damping force characteristic diagram when the shock absorber is on the extension side hard.

FIG. 12 is a damping force characteristic diagram of the shock absorber in a soft state on an extension side and a compression side.

FIG. 13 is a damping force characteristic diagram of the shock absorber in a pressure-side hard state.

FIG. 14 is an explanatory diagram illustrating a main part of the apparatus according to the embodiment.

FIG. 15 is a circuit diagram showing a main part of the device of the embodiment.

FIG. 16 is a circuit diagram showing a main part of the device of the embodiment.

FIG. 17 is a circuit diagram showing a main part of the device of the embodiment.

FIG. 18 is a flowchart illustrating a control operation of a control unit of the embodiment device.

FIG. 19 is a diagram illustrating a map for determining whether a steering condition is satisfied / not satisfied in the example apparatus.

FIG. 20 is a time chart showing the operation of the embodiment device when the steering condition is not satisfied.

FIG. 21 is a time chart showing the operation of the embodiment device when the steering condition is satisfied.

FIG. 22 is a diagram illustrating a control switching line at the time of steering of the example apparatus.

FIG. 23 is a diagram showing a Lissajous waveform of a damping force in the case of steering control of the example device.

[Explanation of symbols]

 a damping force characteristic changing means b suspension unit c vertical movement detecting means d lateral acceleration detecting means e input means f damping force characteristic controlling means

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B60G 17/01 B60G 17/015

Claims (2)

(57) [Claims] 1. A vehicle which is interposed between a sprung portion and a unsprung portion of a vehicle to reduce
Suspension whose damping force characteristics can be changed by damping characteristics changing means
And at least factors related to the vertical behavior of the spring.
Vertical behavior detection means that emits, and the body left and right direction on the spring
Having left and right acceleration detecting means for detecting acceleration of the vehicle
Means, a left-right acceleration obtained by a signal from the left-right acceleration detection means
Degree of change of degree and lateral acceleration, and detection of the vertical behavior
Control signal obtained using the signal obtained from the means
Damping to control damping force characteristics of each suspension unit
Force characteristic control means,A vehicle suspension device comprising: The damping characteristic changing means of the suspension unit may
Soft characteristics with fixed minimum damping characteristics on both pressure and pressure sides
The pressure side is fixed to a low damping characteristic substantially equal to that of the soft characteristic.
The attenuation characteristic on the extension side is kept the same as the maximum attenuation from the low attenuation characteristic
Stretch-side hardware characteristics that are continuously variable up to force characteristics, and stretch-side
Is fixed to the same low attenuation characteristic as that of the soft characteristic.
The compression side damping characteristics range from low to maximum damping force characteristics.
And the pressure-side hardware characteristics that are continuously variable
Is configured to form The damping force characteristic control means includes a lateral acceleration and a lateral acceleration.
Determining whether the steering condition is satisfied based on the rate of change of the degree,
When the steering condition is not satisfied, the
The control signal is formed by the obtained signal, and when the steering condition is satisfied,
Is calculated based on the lateral acceleration and the rate of change of lateral acceleration.
A control signal is formed by the received signal, and based on the control signal,
When the control signal is positive and exceeds a predetermined threshold,
Control by controlling the spence unit to the extension side hardware characteristics
Continuously changes the damping force characteristics on the extension side according to the signal level
When the control signal is within the positive and negative thresholds,
Pressure when the control signal is less than the negative threshold.
Control to the hard side characteristics and the pressure side according to the magnitude of the control signal
The damping force characteristics of the
To A vehicle suspension device characterized by the above-mentioned. 2. The method according to claim 1, wherein the damping force characteristic control means determines whether or not a steering condition is satisfied.
(G) a change rate of the lateral acceleration (△ G) in advance the value obtained by multiplying the
If the steering condition is satisfied when the value is larger than the set value (K),
It is determined that the steering condition is not satisfied if it is small and small.
And the control signal for the front right wheel is VFR, and the control signal for the front left wheel is
VFL, right rear wheel control signal VRR, left rear wheel control signal
Is VRL, the sprung vertical speed of the right front wheel is v1, and the left front wheel is
The vertical speed of the spring is v2, the vertical speed of the right rear wheel is v3,
The sprung vertical speed of the left rear wheel is v4, the pitch rate is VP,
The roll rate is VR, the lateral acceleration is G, and the lateral acceleration is variable.
When the conversion rate is ΔG , VFR = αf (v1 + βfv1 · vP + γfv1 · vR)
+ Af (ΔG + bf G) VFL = αf (v2 + βfv2 · vP−γfv2 · vR)
−af (ΔG + bf G) VRR = αr (v3−βrv3 · vP + γrv3 · vR)
+ Ar (ΔG + br G) VRL = αr (v4−βrv4 · vP−γrv4 · vR)
−ar (ΔG + br G) vP = (v1 + V2−v3−v4) / 2 vR = (v1 + V3−v2−v4) / 2 The control signal of each wheel is obtained by the following equation (αf, α
r, βf, βr, γf, γr, af, and ar are coefficients.
You. ) And when the steering condition is not satisfied, the coefficients af and ar are set to 0,
When the steering conditions are satisfied, the coefficients αf and αr are set to 0.
The vehicle suspension according to claim 1, wherein
Place.