JPH1095213A - Automobile suspension - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the freedom of setting location of a horizontal gravity sensor. SOLUTION: An automotive suspension provides; a damping property control means e which has a normal control member d controlling the damping properties for each shock absorber b responding to the sprung up-and-down behavioral signals detected by a sprung up-and-down behavioral signal detecting means c; a horizontal accelerating detecting means f located at a position away from the center of automotive width by a specified width and detects an automotive horizontal accelerating speed; an operation safety member g which determines steering conditions based on horizontal accelerating signals detected by the horizontal speed detecting means f and controls the steering damping properties of each shock absorber b according to its determined steering condition; a setting position compensation means h for the horizontal accelerating speed detecting means, which compensates the controlling amount of the operation safety damping properties when turning right and left according to the deflection from the center of automotive width to the setting position of the horizontal accelerating speed detecting means f.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle suspension system for optimally controlling a damping force characteristic of a shock absorber.
In particular, the present invention relates to a system for performing vehicle safety control during steering.

[0002]

2. Description of the Related Art Conventionally, as a vehicle suspension device for controlling damping force characteristics of a shock absorber, for example, Japanese Patent Laid-Open Publication No. Hei.
A “suspension control device” described in Japanese Patent No. 237809 is known. This conventional apparatus includes a variable means for increasing and decreasing the damping force of a suspension, a lateral acceleration sensor (hereinafter, referred to as a lateral G sensor) for detecting a lateral acceleration acting on a vehicle body, and an output from the lateral G sensor. Control means for outputting a control signal for increasing or decreasing the damping force of the suspension, the control means including an acceleration signal from the lateral G sensor and a value of an acceleration change rate obtained from the value of the acceleration signal And calculating means for outputting a control signal to the variable means based on the forward and reverse waveform phases of both values.

That is, in this conventional device, when the waveform phase of the acceleration signal from the lateral G sensor and the value of the acceleration change rate obtained from the value of the acceleration signal are the same, the damping force is increased. When the vehicle is in opposite phase, the damping force is reduced, so that when a lateral acceleration occurs in the vehicle body, the vehicle speed and the steering speed, that is, the vehicle can be quickly controlled without distinction between the steady roll and the transient roll. Was something.

[0004]

However, the above-mentioned conventional apparatus has the following problems. That is, there is no problem in the case where the lateral G sensor is installed at the center position in the width direction of the vehicle (see FIG. 20). It is often installed at a position shifted in the width direction from the center position in the width direction (see FIG. 21), and it is desirable that the installation position can be set freely. However, in such a case, a difference occurs in the value of the lateral acceleration signal detected by the lateral G sensor depending on the turning direction of the vehicle due to the steering operation, and as a result, the control amount of the damping force characteristic is reduced. A disadvantage that the direction differs depending on the turning direction of the vehicle occurs.

The present invention has been made in view of the above-mentioned conventional problems, and a lateral G sensor is installed at a position shifted in a width direction from a center position in a width direction of a vehicle without using a steering sensor. However, it is an object of the present invention to provide a vehicle suspension device that can prevent a problem in which a damping force characteristic control amount varies depending on a turning direction of a vehicle, thereby increasing a degree of freedom of a position where a lateral G sensor is installed. Is what you do.

[0006]

In order to achieve the above-mentioned object, a vehicle suspension system according to the present invention is interposed between a vehicle body side and each wheel side as shown in FIG. A shock absorber b whose damping force characteristic can be changed by the damping force characteristic changing means a; a sprung up / down behavior detecting means c for detecting a sprung up / down behavior of the vehicle; and a spring detected by the sprung up / down behavior detecting means c Damping force characteristic control means e having a normal control unit d for controlling damping force characteristics of each shock absorber b in accordance with the up-down motion signal; and a vehicle installed at a position shifted by a predetermined width from a center position in the width direction of the vehicle. A lateral acceleration detecting means f for detecting the lateral acceleration of the vehicle and a lateral acceleration signal provided in the damping force characteristic control means e and detected by the lateral acceleration detecting means f to judge a steering condition and to determine the steering condition. Steering stability controller g which according to the steering conditions performing steering during damping force characteristic control for each shock absorber b
The operation is performed when the vehicle is turning right or left in accordance with the deviation provided from the center position in the width direction of the vehicle to the installation position of the lateral acceleration detection means f provided in the damping force characteristic control means e. Lateral acceleration detecting means installation position correcting means h for correcting the control amount of the stable damping force characteristic control. Further, in the vehicle suspension device according to the second aspect, the correction by the lateral acceleration detecting means installation position correcting means h is performed by correcting the control gain in the steering damping force characteristic control.

[0007]

Since the vehicle suspension system of the present invention is constructed as described above, when the vehicle is traveling straight, the damping force characteristic of each shock absorber b in the normal control section d according to the sprung up / down behavior signal. Control is performed, whereby
When traveling straight ahead, the riding comfort of the vehicle can be ensured. Further, at the time of steering, the steering control unit g determines the steering state from the lateral acceleration signal, and controls the damping force characteristic during steering of each shock absorber b according to the determined steering state. As a result, during steering, the transient roll of the vehicle can be suppressed and steering stability can be ensured.

At the time of the steering, the lateral acceleration detecting means installation position correcting means h turns right in accordance with the deviation width from the center position in the width direction of the vehicle to the installation position of the lateral acceleration detecting means f. The processing for correcting the control amount of the damping force characteristic control at the time of steering is performed at the time of turning and at the time of the left turn, whereby the lateral acceleration detecting means f is shifted to the position shifted in the width direction from the center position in the width direction of the vehicle. Even if it is installed,
Since the occurrence of a problem in which the damping force characteristic control amount differs depending on the turning direction of the vehicle is prevented, the degree of freedom of the installation position of the lateral G sensor can be increased.

[0009]

Embodiments of the present invention will be described with reference to the drawings. (Embodiment of the Invention) FIG. 2 is an explanatory view showing the configuration of a vehicle suspension system according to an embodiment of the present invention, in which four shock absorbers S are interposed between a vehicle body and four wheels.
A _FL , SA _FR , SA _RL , SA _RR ( _FL is the left front wheel,
_FR indicates the right front wheel, _RL indicates the left rear wheel, and _RR indicates the right rear wheel. In describing the shock absorber, when these four points are collectively referred to, and when describing their common configuration, they are simply indicated as SA. ) Is provided. A sprung vertical acceleration sensor (hereinafter, referred to as a vertical G sensor) 1 for detecting a vertical acceleration is provided on the vehicle body in the vicinity of each of the front and rear shock absorbers SA _FL , SA _FR and SA _RR on the left and right sides. _FL , 1
_FR , 1 _RR (the lower right symbols _FL , _FR , _RR correspond to the positions of the respective shock absorbers SA _FL , SA _FR , SA _RR . The same applies to the following description). A lateral acceleration sensor (hereinafter referred to as a lateral G sensor) 2 for detecting lateral acceleration of the vehicle is provided at a position closer to the right end of the vehicle body than the center position in the width direction of the front wheel. The sprung vertical acceleration signals G _FL , G _FR , and G _RR are obtained as positive values when the acceleration direction of the vehicle body is upward, negative values when the acceleration direction is downward, and the lateral acceleration signal Gs Is a positive value when the acceleration direction of the vehicle is from the left wheel to the right wheel (right turning direction of the vehicle), and a negative value when the acceleration direction of the vehicle is from the right wheel to the left wheel direction (left turning direction of the vehicle). can get. In the vicinity of the driver's seat, the upper and lower G sensors 1 _FL , 1 _FR , 1 _RR ,
Further, a control unit 4 is provided which receives a signal from the lateral G sensor 2 and outputs a drive control signal to the pulse motor 3 of each shock absorber SA. FIG. 4 is a system block diagram of FIG. 3 showing the above configuration, in which a control unit 4 includes interface circuits 4a and 4C;
A PU 4b and a drive circuit 4c are provided, and the above-mentioned upper and lower G sensors 1 _FL , 1 _FR , 1 _RR are provided in the interface circuit 4a.
And a signal from the lateral G sensor 2.

FIG. 4 is a sectional view showing the structure of the shock absorber SA.
A is a cylinder 30, a piston 31 that defines the cylinder 30 in an upper chamber A and a lower chamber B, an outer cylinder 33 in which a reservoir chamber 32 is formed on the outer periphery of the cylinder 30, a lower chamber B and a reservoir chamber 32. Base 34 and piston 31
A guide member 35 for guiding the sliding of the piston rod 7 connected to the outer cylinder 33, a suspension spring 36 interposed between the outer cylinder 33 and the vehicle body, and a bump rubber 37.

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 A compression-side damping valve 20 and an extension-side damping valve 12 for opening and closing 31a and 31b, respectively, are provided. A stud 38 that penetrates the piston 31 is screwed and fixed to a bound stopper 41 screwed to the tip of the piston rod 7, and the stud 38 bypasses the through holes 31a and 31b. Communication for forming flow paths (extension-side second flow paths E, expansion-side third flow paths F, bypass flow paths G, and compression-side second flow paths J to be described later) that communicate the upper chamber A and the lower chamber B. A hole 39 is formed.
An adjuster 40 for changing the flow path cross-sectional area of the flow path is rotatably provided in 9. Also, stud 38
The communication hole 3 is formed on the outer periphery of the communication hole 3 in accordance with the direction of fluid flow.
An expansion-side check valve 17 and a compression-side check valve 22 that allow and shut off the flow on the flow path side formed by 9 are provided. Note that the adjuster 40 is provided with the pulse motor 3.
Is rotated through the control rod 70 (see FIG. 4). Also, studs 38
A first port 21, a second port 13, a third port 18, a fourth port 14, and a fifth port 16 are formed in this order from the top.

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. I have.

Therefore, between the upper chamber A and the lower chamber B, a through-hole 31 is formed as a flow path through which fluid can flow in the extension stroke.
b, the inside of the extension side damping valve 12 is opened to open the lower chamber B
, The second port 13, the vertical groove 23,
Via the second port 13, the vertical groove 23, and the fifth port 16 via the fourth port 14, the outer peripheral side of the extension side damping valve 12 is opened to open the outer peripheral side of the extension side damping valve 12 to reach the lower chamber B, and the second port 13, the vertical groove 23, and the fifth port 16. Then, the extension side check valve 17 is opened to open the extension side third flow path F to the lower chamber B, and the bypass to the lower chamber B via the third port 18, the second horizontal hole 25, and the hollow portion 19. There are four flow paths G. In addition, as a flow path through which a fluid can flow during the pressure stroke, the pressure side first valve that opens the pressure side damping valve 20 through the through hole 31a.
Channel H, hollow portion 19, first lateral hole 24, first port 21
, The pressure-side second flow path J that opens the pressure-side check valve 22 to reach the upper chamber A through the air passage, and the bypass flow that reaches the upper chamber A through the hollow portion 19, the second horizontal hole 25, and the third port 18. Road G
And three flow paths.

That is, the shock absorber SA is configured such that the damping force characteristic can be changed in multiple steps by rotating the adjuster 40 with the characteristics shown in FIG. 6 on both the extension side and the compression side. That is, as shown in FIG.
The state in which both pressure sides are soft (hereinafter, soft area SS
When the adjuster 40 is rotated counterclockwise from
When the damping force characteristic can be changed in multiple stages only on the extension side and the compression side is a region fixed to the low damping force characteristic (hereinafter referred to as the extension side hard region HS). Conversely, when the adjuster 40 is rotated clockwise, Only the compression side has a structure in which the damping force characteristic can be changed in multiple stages, and the extension side is a region fixed to the low damping force characteristic (hereinafter referred to as a compression side hard region SH).

In FIG. 7, the KK section, the LL section, the MM section, and the NN section in FIG. 5 when the adjuster 40 is arranged at the position of, respectively. 8, 9 and 10 and the damping force characteristics at each position are shown in FIGS.

Next, the content of the damping force characteristic control operation in the control unit 4 will be described with reference to the block diagram of FIG. First, in A1, each upper and lower G sensor 1
The sprung vertical acceleration signal G (G _FR , G _FL , G _RR ) obtained from (1 _FR , 1 _FL , 1 _RR ) is converted to a sprung vertical speed signal Vn.
A speed conversion process is performed for conversion into _FR , Vn _FL , and Vn _RR . That is, the speed conversion processing unit includes a high-pass filter HPF that converts the speed by integration, and a low-pass filter LPF and a high-pass filter HPF that form a band-pass filter that cuts frequencies other than the sprung resonance frequency band. . The sprung vertical speed signal Vn _{RL at} the left rear wheel position is calculated.

At A2, the sprung vertical speed signal V
A bounce component, a pitch component and a roll component are extracted from n _FR , Vn _FL , Vn _RR and Vn _RL . That is, the respective sprung mass vertical velocity signal _{Vn FR, Vn FL, Vn RR} , Vn RL
Constitutes the bounce component at each wheel position, pitch component V _P is sprung mass vertical velocity signal Vn at the right front wheel position
_FR and sprung vertical speed signal Vn _{RR at} right rear wheel position
And the roll component V _R is calculated from the difference between the sprung vertical velocity signals Vn _FL and Vn _{FR at the} left and right front wheel positions.
(The following equation (2)). Then, in this embodiment, the pitch component V _P is, when the vehicle is squat direction a positive value, when the dive direction is obtained by a negative value. Further, the roll component V _R is the direction in which the vehicle body is inclined to the left at a positive value, obtained in a negative value in the direction inclined to the right.

[0018] _{V P = Vn FR -Vn RR ············} (1) V R = Vn FR -Vn FL ············ (2) Continued In A3, the normal control signal V (VFR, VFL, VRR, VR) of the shock absorber SA at each wheel position used in the normal control based on the following equations (3) to (6).
L) Create. Front wheel right _{VFR = α f · Vn FR +} β f · V P + r f · V R ·············· (3) front wheel left _{VFL = α f · Vn FL +} β f · V P _{-r f · V R ·············· (4} ) rear wheel right _{VRR = α r · Vn RR -β} r · V P + r r · V R ······ ........ (5) rear wheel left _{VRL = α r · Vn RL -β} r · V P -r r · V R ·············· (6) Note that α _f , β _f , and γ _f are gains for the front wheels α _r , β _r , and γ _r are gains for the rear wheels.

In A4, the lateral acceleration signal GY detected by the lateral G sensor 2 is converted into a rate of change in acceleration, whereby the roll rate signals for the front and rear wheels are obtained. That is, the second-order low-pass filter LPF
By performing the processing, a signal substantially equivalent to the roll signal of the vehicle body is obtained. The roll rate signal is obtained by differentiating the signal, and the high-frequency noise generated by the differentiation is cut by a first-order low-pass filter LPF. GV can be determined. Then, each roll rate gain Ksf-L,
By multiplying Ksf-R, Ksr-L and Ksr-R respectively,
The roll rate signals GV _FL , GV _FR , GV _RL , GV _{RR at the} left and right front wheel positions and the left and right rear wheel positions are obtained.

On the other hand, at A5, the lateral acceleration signal GY detected by the lateral G sensor 2 is converted to a secondary low-pass filter LP.
F, a roll angle signal GR of the vehicle body is obtained, and the roll gain signals Kgf-L, Kgf-R, Kgr-L, K
Each of the roll angle signals GR _FL , G at each of the front wheel left and right positions and the rear wheel left and right positions is multiplied by gr-R.
R _FR , GR _RL and GR _RR are determined.

At A6, the roll rate signals GV _FL , GV _FR for the front left and right wheels and the roll angle signals G for the left and right front wheels are generated.
R _FL, GR _FR and respectively adding the front wheel left and right steering correction upon signal Vs _-fl, Vs _-fr is determined and also the A7,
The rear-wheel left and right roll rate signal GV _RL, GV _RR and rear-wheel-side left and right roll angle signal GR _RL, when wheel steering after adding the GR _RR correction signal _Vs -rL, Vs _-rR is required.

At A8, as shown in the following equations (7) to (10), each of the normal control signals V (VFR, VFL, VRR, VR)
L), the steering control signals Vs (VsFR, VsFL, VsFL, VsFL, Vs- _fL , Vs- _fL , Vs- _rL , Vs- _rL , Vs- _rL , Vs- _rL) VsRR
, VsRL).

Front wheel right VsFR = VFR + Vs- _fR (7) Front wheel left VsFL = VFL-Vs- _fL ... (8) Rear wheel right VsRR = VRR + Vs _-rR 9) Rear wheel left VsRL = VRL-Vs _-rL (10) Finally, in A9, the following equations (11) to (14) ) Or (15)-(18)
Based on the target damping force characteristic position P (P _FR , P _FL , P _RR , P _RL ) in the normal control or the operation control.
Is performed.

[0024] The front wheel right _{P FR = VFR · a f ······················} (11) front wheel left P _FL = VFL · a _f ···· .................. (12) rear wheel right P _RR = VRR · a _r ··················· (13) rear wheel left _{P RL = VRL · a r ······················} (14) It should be noted, a _f is of the front-wheel-side normal time gain, a _r is a normal gain of the rear wheel side.

[0025] The front wheel right _{P FR = VsFR · b f ·····················} (15) front wheel left P _FL = VsFL · b _f ····· · · · · · · (16) rear wheel right P _RR = VsRR · b _r ····················· (17) rear wheel left _{P RL = VsRL · b r ·····················} (18) Note that, b _f is the front wheel side of the steering stability during gain, _br is a steering-time gain on the rear wheel side.

Next, among the control operations of the control unit 4, the contents of the normal control by the normal control unit are shown in FIG.
5 will be described based on the time chart. When the normal control signal V based on the sprung vertical speed Vn changes as shown in this figure, when the normal control signal V is 0, the shock absorber SA is controlled to the soft region SS.

When the normal control signal V becomes a positive value, the compression side is controlled to the expansion side hard region HS to fix the compression side to the low damping force characteristic, while the expansion side damping force characteristic is changed to the normal control signal. (VFR, VFL, VRR, VRL).
That is, the target damping force characteristic position P (P _FR , P _FL , P _RR , P _RL ) of each shock absorber SA is calculated by the above equation (11).
Drive control is performed to the value determined based on (14).

When the normal control signal V becomes a negative value, the compression side hard region SH is controlled to fix the extension side to the low damping force characteristic, while the compression side damping force characteristic is changed to the normal control signal ( VFR, VFL, VRR, VRL).
That is, also in this case, the target damping force characteristic position P (P _FR , P _FL , P _RR , P _RL ) of each shock absorber SA is drive-controlled to a value determined based on the above equations (11) to (14). I do.

In the time chart of FIG.
Region a is a state in which the normal control signal V is reversed from a negative value (downward) to a positive value (upward), but at this time, the relative speed between the sprung and unsprung is still a negative value (shock). Since the stroke of the absorber SA is a pressure stroke side), at this time, the shock absorber SA is controlled to the extension side hard region HS based on the direction of the normal control signal V. In the region, the pressure stroke side, which is the stroke of the shock absorber SA at that time, has soft characteristics.

In the area b, the relative speed is switched from a negative value to a positive value (the stroke of the shock absorber SA is extended) while the normal control signal V remains a positive value (upward). At this time, the shock absorber SA is controlled to the extension-side hard region HS based on the direction of the normal control signal V, and the stroke of the shock absorber is also the extension stroke. In this case, the extension stroke, which is the stroke of the shock absorber SA at that time, has a hardware characteristic proportional to the value of the normal control signal V.

Area c is a state in which the normal control signal V is reversed from a positive value (upward) to a negative value (downward). At this time, the relative speed is still a positive value (shock absorber SA). Is a region on the extension stroke side), and at this time, the shock absorber SA is controlled to the compression side hard region SH based on the direction of the normal time control signal V. Therefore, in this region, The extended stroke side, which is the stroke of the shock absorber SA, has soft characteristics.

A region d is a region where the normal speed control signal V remains a negative value (downward) and the relative speed changes from a positive value to a negative value (the stroke of the shock absorber SA is on the extension stroke side). Therefore, at this time, the shock absorber SA is controlled to the compression side hard region SH based on the direction of the normal time control signal V, and the stroke of the shock absorber is also the compression stroke. The pressure stroke side, which is the stroke of the shock absorber SA, has a hard characteristic proportional to the value of the normal control signal V.

As described above, in this embodiment, when the sprung vertical speed and the relative speed between the sprung and unsprung are the same sign (region b, region d), the stroke of the shock absorber SA at that time. And the damping force characteristic control based on the skyhook control theory, in which the side of the shock absorber SA at the time of different sign (region a, region c) is controlled to a soft characteristic. Is performed without detecting the relative speed between the sprung and unsprung portions. Further, in this embodiment, when shifting from the area a to the area b and from the area c to the area d, the switching of the damping force characteristic is performed without driving the pulse motor 3.

Next, among the control operations of the control unit 4, the contents of the switching control operation between the normal control and the operation control will be described with reference to the flowchart of FIG. 16 and the time chart of FIG.

Firstly, flow of 16 - will be described based on the bets, in that step 201, Russia - - Cha Relais - absolute value of bets components | whether is ON threshold G _SN or | G _S Is determined, and if YES, the process proceeds to step 202, where the roll rate component G _S flag is set to ON, and
Go to 03.

In step 203, the absolute value of the roll component
| G _R | After it is determined whether a predetermined ON threshold G _RP above, set to ON roll component G _R flag proceeds to step 204, if YES, the process proceeds to step 205.

In step 205, it is determined whether or not the operation control execution flag is ON. If YES, the process proceeds to step 207 to perform operation control by the operation control unit. After proceeding to step 206 to turn on the safety control flag, the process proceeds to step 207 to perform the control at the time of safety, thereby ending one control flow.

On the other hand, in step 201, NO (| G _S |
When it is determined that < _GSN ), the process proceeds to step 208.
In this step 208, the roll rate component G
It is determined whether or not the _S flag is ON. If YES, the process proceeds to step 209 to reset the OFF timer, and further proceeds to step 210 to newly start the OFF timer, and furthermore, the roll rate component G _S Flag O
After the FF is set, the process proceeds to step 205, and NO
If so, the process proceeds to step 211.

In step 211, it is determined whether or not the OFF timer has already been started. If YES, the process proceeds to step 212, and if NO, the process proceeds to step 213.
After resetting the OFF timer and turning off the operation control execution flag, the process proceeds to step 214 for performing the normal control.

In step 212, it is determined whether or not the timer count T of the OFF timer has exceeded a predetermined time T _S. If YES, the process proceeds to step 213, and
If NO, the process proceeds to step 205.

In step 203, NO (| G _R
When it is determined that | <G _RP ), the routine proceeds to step 215. Then, in step 215, the roll component G _R
Flag determines whether or not turned ON, and resets the OFF timer proceeds to step 216, if YES, the newly started the OFF timer further proceeds to Step 217, and the roll component G _R flag After the switch is turned off, the process proceeds to step 205, and if NO, the process proceeds to step 218.

In step 218, it is determined whether or not the OFF timer has already been started. If YES, the process proceeds to step 219;
Proceed to 13.

In step 219, it is determined whether or not the timer count T of the OFF timer has exceeded a predetermined time T _S. If YES, the process proceeds to step 213.
If NO, the process proceeds to step 205. Thus, one control flow is completed, and thereafter, the above control flow is repeated.

Next, the contents of the control during operation in step 207 will be described with reference to the flowchart of FIG.
First, in step 301, it is determined whether or not the lateral acceleration signal GY detected by the lateral G sensor 2 is greater than 0, thereby determining the steering direction (turning direction) of the vehicle.
When ES (GY> 0), the vehicle is turning right due to steering in the right direction.
To the respective gains (the roll rate gains Ksf-L, Ksf-R, Ksr-L, Ksr-R for the front wheel left and right and the rear wheel left and right, the roll gain Kgf-L for the front wheel left and right and the rear wheel left and right, Kgf
-R, Kgr-L, Kgr-R) are all set to 1, then step 3
04, and when NO (GY ≦ 0), the vehicle is turning left by steering to the left, and in this case, the process proceeds to step 302, where each gain (front left / right and rear wheels) Left and right roll rate gains Ksf-L, Ksf-R,
Ksr-L, Ksr-R, and the roll gains Kgf-L, Kgf-R, Kgr-L, and Kgr-R on the front left and right sides and the rear wheel left and right are calculated based on the map of FIG. Depending on
After setting to 1 or more, the process proceeds to step 304.

In step 304, the equations (7) to (1)
0), the normal control signals V (VFL, VFR,
VRL, VRR), the steering control signals Vs (VsFL, VsFR) _obtained by adding or subtracting the steering correction signals Vs- _fL , Vs- _fR , Vs- _rL , Vs- _rR for the left and right front wheels or the left and right rear wheels.
, VsRL, VsRR), and the target damping force characteristic position P of each shock absorber SA is calculated from the operation control signal Vs based on the equations (15) to (18).

Next, among the control operations of the control unit 4, the contents of the switching control operation between the normal control and the operation control will be described with reference to the time chart of FIG. (B) Straight running When the vehicle is running straight on a good road, the absolute value of the roll component | G _R | is less than a predetermined ON threshold value G _RP , and the absolute value of the roll rate component | Gs | is also less than the ON threshold value Gs- _N . At this time, the damping force characteristic control of each shock absorber SA is performed by the normal control.

That is, in the normal control, the bounce components V _FL and V _FL obtained from the sprung vertical speed signal Vn are used.
_FR, V _RL, the normal operation control signal V obtained based on the V _RR and the pitch component V _P and the roll component V _R, the damping force characteristic control for each shock absorber SA is performed.

Accordingly, not only the bounce but also the vehicle behavior in which the pitch and the steady roll are trained on the bounce can exert sufficient vibration damping properties, and thereby, the riding comfort of the vehicle when traveling straight ahead. And steering stability can be ensured.

(B) During Steering When steering is performed and lateral acceleration acts on the vehicle, the absolute value | G _R | of the roll component becomes greater than or equal to a predetermined ON threshold value G _RP , and the absolute value of the roll rate component is obtained. The value | Gs |
At this time, the damping force characteristic of each shock absorber SA is controlled by the operation-time control since it is _{equal to} or more than the fixed ON threshold value Gs- _N .

That is, in this operation control, the bounce components V _FL and V _FL obtained from the sprung vertical speed signal Vn are used.
_FR, V _RL, the normal operation control signal V obtained based on the V _RR and the pitch component V _P and the roll component V _R, furthermore, during the steering operation correction signal _{Vs -fL, Vs -fR, Vs -rL} , Vs - The damping force characteristic of each shock absorber SA is controlled based on the steering control signal Vs obtained by adding or subtracting _rR . Therefore, the transient roll of the vehicle based on steering can be sufficiently suppressed by the high damping force characteristics, and the steering stability of the vehicle during steering can be ensured.

Further, when the vehicle turns right and left,
Since a difference occurs in the value of the lateral acceleration signal, each gain in the left turn is corrected to a large value of 1 or more in proportion to the value of the lateral acceleration signal GY based on the gain 1 in the right turn. Processing is performed.

This is because the lateral G sensor 2 is installed at a position deviated in the width direction from the center position in the width direction of the vehicle, so that the lateral acceleration signal is obtained when the vehicle turns right and left. This is because it is necessary to correct the difference because a difference occurs in the value of.

That is, as shown in FIG. 20, the force F acting on the center of gravity of the vehicle (the position where the lateral G sensor 2 is installed) during the turning movement of the vehicle can be expressed by the following equation (19). F = m · r · ω ² = m · v ² / r (19) where m is the vehicle mass, ω is the angular speed, and v is the turning speed. , R is the turning radius.

However, the layout of the lateral G sensor 2 as shown in FIG. 20 is not always an ideal place due to the problem of mounting on a vehicle. Therefore, when the layout of the lateral G sensor 2 for detecting the lateral acceleration of the vehicle is shifted to the right from the center position in the width direction of the vehicle as shown in FIG.
Turning radius r at the time of the turning radius r _R and the left turn at the time of the right turn of the vehicle
_{Since L} is different (r _R <r _L ), as shown in the following equations (20) and (21), the level of the force F acting on the installation position of the lateral G sensor 2 differs depending on the turning direction of the vehicle. (F _R >
F _L ).

[0055] a right turn when ^{_{F R = m · v 2 /}} r R ················· (20) left turn when the ^{_{F L = m · v 2 /}} r L (21) Therefore, if the detection signal value of the lateral G sensor 2 is used as it is for the damping force characteristic control of each shock absorber SA,
The control force differs depending on the turning direction of the vehicle. Therefore, the forces F _R , F acting on the installation position of the lateral G sensor 2
The level difference of _L is used to calculate the control signal Vs at the time of operation (the roll rate gains Ksf-L, Ksf-R, Ksr-L, Ksr-R for the front wheel left and right and rear wheel left and right, and the front wheel side). Left and right and rear wheel side left and right roll gains Kgf-L, Kgf-R, Kgr-L,
Kgr-R) is corrected by setting variably to a value of 1 or more in proportion to the value of the lateral acceleration signal GY with reference to 1 during a right turn and 1 at a left turn in proportion to the value of the lateral acceleration signal GY. This is to eliminate the difference in control force generated depending on the direction.

As described above, according to the embodiment of the present invention, the following effects can be obtained. To provide a vehicle suspension system that is excellent in ride comfort and steering stability because it can generate sufficient control force not only for bounces but also for pitches and steady rolls by normal control during straight running. Can be.

[0057] The steering state is detected without using a steering sensor, whereby the transient roll of the vehicle during steering can be sufficiently suppressed, and the steering stability of the vehicle can be ensured.

Regardless of the installation position of the lateral G sensor 2, it is possible to eliminate the mismatch of the control force depending on the turning direction of the vehicle, thereby increasing the degree of freedom of the installation position of the lateral G sensor 2.

Although the embodiments of the present invention have been described above, the specific configuration is not limited to the embodiments of the present invention, and even if there is a design change or the like within a range not departing from the gist of the present invention, the present invention is not limited thereto. Included in the invention.

For example, in the embodiment of the present invention, a case is shown in which a vertical G sensor for detecting a sprung vertical acceleration is provided at a total of three locations, that is, two locations on the left and right sides of the front wheel and one location on the right side of the rear wheels. As shown in the block diagram of FIG. 7, only two positions on the left and right sides of the front wheel may be used, and for the two positions on the left and right sides of the rear wheel, the sprung vertical acceleration may be estimated at A0 based on a predetermined transfer function equation.

Further, in the embodiment of the present invention, the difference in the control force generated depending on the turning direction of the vehicle is corrected by varying each gain when calculating the operation control signal Vs. The operation-time gain b _f . Used in equations (15) to (18) for obtaining the target damping force characteristic position P during operation control. _br may be variable.

In the embodiment, when one of the stroke sides is variably controlled to the hard characteristic side, the shock absorber having a structure in which the reverse stroke side is fixed to the soft characteristic is used. The present invention can also be applied to a system using a shock absorber having a structure in which force characteristics are variably controlled in the same direction.

[0063]

As described above, the vehicle suspension system according to the present invention can be used when the vehicle is turning right or left depending on the deviation from the center position in the width direction of the vehicle to the installation position of the lateral acceleration detecting means. With the configuration including the lateral acceleration detecting means installation position correcting means for correcting the control amount of the damping force characteristic control at the time of driving, the position of the lateral G sensor shifted in the width direction from the center position in the width direction of the vehicle. Even if the lateral G sensor is installed, it is possible to prevent the occurrence of a problem in which the damping force characteristic control amount differs depending on the turning direction of the vehicle, thereby increasing the degree of freedom in the installation position of the lateral G sensor. The effect is obtained.

[Brief description of the drawings]

FIG. 1 is a view corresponding to 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 illustrating a vehicle suspension device according to an embodiment of the present invention.

FIG. 4 is a sectional view showing a shock absorber applied to the embodiment of the present invention.

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 characteristic diagram of a damping force characteristic 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 a block diagram showing the details of signal processing and damping force characteristic control operation in the embodiment of the present invention.

FIG. 15 is a time chart showing the contents of normal control by a normal control unit in the control operation of the control unit according to the embodiment of the present invention.

FIG. 16 is a flowchart showing the contents of switching control between normal control and operation control among control operations of the control unit according to the embodiment of the present invention.

FIG. 17 is a time chart showing the contents of switching control between normal control and operation control among control operations of the control unit in the embodiment of the present invention.

FIG. 18 is a flowchart showing details of control during operation according to the embodiment of the present invention.

FIG. 19 is a map showing a variable characteristic of a gain with respect to a lateral acceleration signal in the embodiment of the present invention.

FIG. 20 is an explanatory diagram for explaining a force acting on the position of the center of gravity of the vehicle when the vehicle turns.

FIG. 21 is an explanatory diagram for describing a force acting on the lateral G sensor during turning of the vehicle according to the embodiment of the present invention.

FIG. 22 is a block diagram showing contents of signal processing and damping force characteristic control operation in another embodiment of the present invention.

[Explanation of symbols]

 a damping force characteristic changing means b shock absorber c sprung up / down behavior detecting means d normal control part e damping force characteristic controlling means f lateral acceleration detecting means g operation control part h lateral acceleration detecting means installation position correcting means

Claims (2)

[Claims] 1. A shock absorber interposed between a vehicle body side and each wheel side and capable of changing a damping force characteristic by damping force characteristic changing means, and a sprung vertical motion detection for detecting a sprung vertical motion of the vehicle. Means; damping force characteristic control means having a normal control unit for controlling damping force characteristics of each shock absorber in accordance with a sprung vertical movement signal detected by the sprung vertical movement detecting means; A lateral acceleration detecting means provided at a position shifted by a predetermined width to detect a lateral acceleration of the vehicle; and a steering provided from the lateral acceleration signal detected by the lateral acceleration detecting means provided in the damping force characteristic control means. A steering control unit that determines a situation and controls a damping force characteristic during steering of each shock absorber according to the determined steering condition; and a damping force characteristic control unit. Lateral acceleration detection that corrects the control amount of the damping force characteristic control during steering between right and left turns of the vehicle according to the shift width from the center position in the width direction of the vehicle to the installation position of the lateral acceleration detecting means. And a vehicle installation position correcting unit. 2. The vehicle suspension system according to claim 1, wherein the correction by the lateral acceleration detecting means installation position correcting means is performed by correcting a control gain in steering damping force characteristic control.