JPH0316815A - Suspension device for vehicle - Google Patents

Abstract

PURPOSE:To eliminate unstable traveling feeling by changing the setting of mode to the control gain in response to that mode when the mode is shifted from the operational status of control attaching importance to riding quality to the operational status of control attaching importance to traveling stability, or to the operational status reverse to this. CONSTITUTION:A control unit 17 inputs respective signals of the pump discharge pressure from sensors 12-15, the fluid pressure, the car height displacement, and the vertical acceleration of gas springs 5, controls proportional flow control valves 9 to drive flow pressure cylinder devices 3, and changes the suspension characteristic. Based on the signals of a rubber angle sensor 18 and a car speed sensor 19, the control gain is changed to the value of new mode at once when a vehicle changed from the operational status of control attaching importance to riding quality to the operational status of control attaching importance to traveling stability. On the other hand, when shifted to the operational status reverse to the above-mentioned, setting of control gain is successively changed to the value of next mode. Thus, a feeling of physical disorder and an unstable traveling feeling caused on a driver can be effectively prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a suspension system for a vehicle, and more particularly to an active suspension system that can change suspension characteristics as desired. It is something.

Prior Art Suspension devices known as passive suspensions have traditionally been composed of a hydraulic shock absorber and a damper unit made of a spring such as a coil spring.The suspension characteristics can be adjusted by varying the damping force of the hydraulic shock absorber. Although it is possible to change the characteristics to some extent, the range is small, and in practice, the suspension characteristics of passive suspension devices are set uniformly.

In contrast, in recent years, a fluid cylinder device is provided between the sprung mass and the unsprung mass, and by controlling the supply and discharge amount of working fluid to this fluid cylinder device,
A suspension device called an active suspension that can change the suspension characteristics as desired has been proposed (for example, Japanese Patent Publication No. 59-143
No. 65, JP-A-63-130418, etc. )
.

Generally, there are three types of vehicle vibration: bounce, pitch, and roll, and such active suspension systems include a fluid cylinder device for each wheel.
In order to improve riding comfort and running stability against these three types of vehicle vibrations, the supply and discharge amount of working fluid to the fluid cylinder device of each wheel is set and controlled according to the vehicle operating condition. The control is performed by controlling the opening degree of the flow control valve of each wheel using a predetermined control gain.

Problems to be Solved by the Invention As described above, the active suspension device adjusts each wheel to improve riding comfort and running stability against three types of vehicle vibrations, depending on the driving condition of the vehicle. In order to control the supply and discharge of working fluid to the fluid cylinder device with a predetermined control gain, the operating state of the vehicle is detected,
The system is equipped with a suspension characteristic control means that changes the settings of each control gain, but in conventional active suspension systems, when the driving condition changes, regardless of the degree of the change, it is necessary to perform control that emphasizes ride comfort. When there is a transition from a driving state to a driving state where control should be performed with an emphasis on driving stability, and when there is a transition from a driving state where control must be performed with an emphasis on driving stability to a driving state where control must be performed with an emphasis on riding comfort. In both cases, the suspension characteristic control means adjusts each control gain to
Suspension control is performed by immediately changing the setting to a predetermined control gain determined based on the new driving condition. Therefore, if the driving condition changes significantly, it may give the driver a sense of discomfort. In particular, when transitioning from a driving state where control should be performed with an emphasis on driving stability to a driving state where control must be performed with an emphasis on ride comfort, the driver may experience a transient sense of unstable driving. Ta.

Purpose of the Invention The present invention has a fluid cylinder device for each wheel between the sprung weight and unsprung weight of the vehicle, and adjusts the suspension characteristics based on a plurality of modes depending on the driving condition of the vehicle. a suspension characteristic control means for setting and controlling a control gain of the suspension characteristic control means; and a displacement detection means for detecting displacement of the vehicle; and a predetermined control set and controlled by the suspension characteristic control means based on the detection result of the displacement detection means In an active suspension system that controls the amount of working fluid supplied and discharged to the fluid cylinder system using a gain to cancel out the displacement of the vehicle, it may cause discomfort or instability to the driver even when the driving condition changes significantly. The object of the present invention is to provide an active suspension device that does not give a bad driving feeling.

Structure and Function of the Invention An object of the present invention is for the suspension characteristic control means to change the driving state of the vehicle from a driving state where control should be performed with emphasis on riding comfort to a driving state where control should be performed with emphasis on ride comfort, based on the output of the driving state detection means. When the vehicle transitions to a driving state where control should be performed with emphasis on driving stability, the control gain should be immediately changed to the mote control gain that corresponds to the new driving state, and on the other hand, control should be performed with emphasis on running stability. When the operating state shifts to an operating state where control that emphasizes ride comfort is performed, the control gain is sequentially changed to the control gain of the next mote, and the control gain is changed to the control gain of the mote corresponding to the new operating state. This is achieved by being configured to change the settings.

According to the present invention, when the driving state of the vehicle shifts from a driving state in which control with emphasis on riding comfort is to be performed to a driving state in which control with emphasis on running stability is to be performed, the suspension characteristic control means immediately controls the suspension characteristics. Since the suspension control is performed by changing the control gain settings according to the new driving condition, driving stability is not compromised, and on the other hand, ride comfort is improved from driving conditions that should be controlled with emphasis on driving stability. When the driving state shifts to a state where important control is required, the suspension characteristic control means
Suspension control is performed so that the control gain is sequentially changed to the control gain of the next mote, and the control gain is changed to the control gain of the mode corresponding to the new driving condition. In addition, it is possible to effectively prevent an unstable driving feeling when the driving condition changes significantly.

EXAMPLES Hereinafter, examples of the present invention will be described in detail based on the accompanying drawings.

FIG. 1 is an overall schematic diagram of a vehicle including a suspension device for a vehicle according to an embodiment of the present invention.

Although only the left side of the vehicle body 1 is shown in FIG. 1, the right side of the vehicle body 1 is similarly constructed. In FIG. 1, between the vehicle body 1 and the left front wheel 2PL and between the vehicle body 1 and the left rear wheel 2RL, a fluid cylinder device 3,
There are three. A hydraulic chamber 3c is formed in each fluid cylinder device 3 by a piston 3b fitted into a cylinder body 3a. The upper end of the piston rod 3d connected to the piston 3b of each fluid cylinder 3 is connected to the vehicle body 1, and each cylinder body 3a is connected to the left front wheel 2.
It is connected to the PL or left rear wheel 2RL.

The hydraulic chamber 3c of each fluid cylinder device 3 communicates with the gas spring 5 through a communication passage 4, and each gas spring 5 is divided into a gas chamber 5f and a hydraulic chamber 5g by a diaphragm 5e. The pressure chamber 5g communicates with the hydraulic pressure chamber 3c of the fluid cylinder device 3 through the communication passage 4 and the piston 3b of the fluid cylinder device 3.

Hydraulic pump 8 and each fluid? The fluid passage 1o that connects the ring device 3 so as to be able to supply fluid has a flow rate of the fluid supplied to the fluid cylinder device 3 and a flow rate of the fluid supplied to the fluid cylinder device 3.
A proportional flow control valve 9 that controls the flow rate of fluid discharged from the
, 9 are provided, respectively.

The hydraulic pump 8 includes a discharge pressure gauge 1 that detects the discharge pressure of fluid.
2 are provided, and the hydraulic pressure chamber 3 of each fluid cylinder device 3 is provided.
Hydraulic pressure sensors 13 and l3 are provided to detect the hydraulic pressure in c.

Further, vehicle height displacement sensors 14 and 14 are provided which detect the cylinder stroke amount of each fluid cylinder device 3 and detect the vertical displacement of the vehicle body relative to each wheel 2FL and 2RL, that is, the vehicle height displacement. Vertical acceleration sensors 15, 15 detect the vertical acceleration of the wheels 2PL, 2RL, that is, the vertical acceleration of the springs of the wheels 2PL, 2RL.
, 15 are the left and right front wheels 2PL, 2 on a substantially horizontal plane of the vehicle.
A total of three sensors are provided, one above the PR and one in the center of the left and right rear wheels in the vehicle width direction, and a steering angle sensor 18 and a vehicle speed sensor 19 are provided, respectively.

Detection signals from the discharge pressure gauge 12, hydraulic pressure sensors 13, 13, vehicle height displacement sensors 14, 14, vertical acceleration sensors 15, 15, 15, steering angle sensor 18, and vehicle speed sensor 19 are sent to a control unit 17 having a CPU, etc. therein. Based on these detection signals, the control units 1 and 17 perform calculations according to a predetermined program and control the proportional flow control valves 9 and 9 to variably control the suspension characteristics as desired. 9 10 .

FIG. 2 shows fluid cylinder devices 3, 3,
3 is a circuit diagram of a hydraulic circuit that supplies fluid to or discharges fluid from these.

In FIG. 2, the hydraulic pump 8 is a hydraulic pump 2l for a power steering device driven by drive #20.
An accumulator 22 is connected to a discharge pipe 8a which is connected in parallel with the hydraulic pump 21 and discharges fluid from the hydraulic pump 21 to the fluid cylinder devices 3, 3, 3, 3. On the downstream side,
It branches into a front wheel side pipe 23F and a rear wheel side pipe 23R. The front wheel side piping 23F branches into a left front wheel side piping 23FL and a right front wheel side piping 23PR on the downstream side of the branching part with the rear wheel side piping 23R, and the left front wheel side piping 23FL and the right front wheel side piping 23FR are, respectively, It communicates with the hydraulic chambers 3C, 3C of the left front fluid cylinder device 3PL and the right front fluid cylinder device 3FR. Similarly, the rear wheel side pipe 23R branches into a left rear wheel side pipe 23RL and a right rear wheel side pipe 23RR on the downstream side of the branching part, and the left rear wheel side pipe 23R branches into a left rear wheel side pipe 23RL and a right rear wheel side pipe 23RR.
RL and the right rear wheel side pipe 23RR communicate with the hydraulic chambers 3c, 3c of the fluid cylinder device 3RL for the left rear wheel and the fluid cylinder device 3RR for the right rear wheel, respectively.

These fluid cylinder devices 3PL, 3FR, 3RL
, 3RR have gas springs 5FL, 5FR,
5RL and 5RR are connected, each gas spring 5
PL, 5FR, 5RL and 5RR are composed of four gas spring units 5a, 5b, 5c and 5d, and these gas spring units 5a, 5b, 5c and 5d are connected to corresponding fluid cylinder devices 3FL and 3, respectively. FR, 3R
It is connected to a communication path 4 that communicates with the hydraulic pressure chambers 3c, 3c, 3C, and 3C of L and 3RR by branch communication paths 4a, 4b, 4c, and 4d. In addition, each gas spring 5FL, 5'F
R, 5RL, 5RR branch communication paths 4a, 4b, 4c
and 4d have orifices 25a and 25b, respectively.
, 25c, and 25d are provided, and 11 l2 ? This is intended to reduce high-frequency vibrations applied to the vehicle.

Gas spring units 5a, 5b, 5'c, 5d constituting each gas spring 5FL, 5FR, 5RL, 5RR, each fluid cylinder device 3FL, 3FR, 3RL, and 3
RR hydraulic chambers 3c, 3c13c, 3c. The communication path 4 between the first gas spring unit 5a provided at the position closest to the first gas spring unit 5a and the second gas spring unit 5b adjacent thereto has an open position for opening the communication path 4 and an opening position for opening the communication path 4. A switching valve 26 is provided that adjusts the passage area of the communication passage 4 by taking the closed position that narrows the area, and switches the damping force of the gas springs 5FL, 5FR, 5RL, and 5RR into two stages. FIG. 2 shows the switching valve 26 in the open position.

An unload relief valve 28 is connected to the discharge pipe 8 a of the hydraulic pump 8 near the upper waterfall side of the connection part of the accumulator 22 .
When the oil discharge pressure measured in step 2 is above a predetermined upper limit value, the valve is switched to the open position. The oil discharged from the hydraulic pump 8 is directly returned to the reserve tank 29, and the accumulated pressure of the oil pressure in the accumulation rake 22 is controlled to be maintained at a predetermined value. In this way, oil is supplied to each fluid cylinder device 3 from the accumulator 2 which is maintained at a predetermined pressure accumulation value.
2 This is done by storing oil. FIG. 2 shows the unload relief valve 28 in the closed position.

Since the hydraulic circuits for the left front wheel, right front wheel, left rear wheel, and right rear wheel are configured in the same way, only the hydraulic circuit for the left front wheel will be explained below, and for the others, this will be omitted. Omitted.

■The proportional flow control valve 9 is a three-way valve, with a closed position where all ports are closed, a supply position where the left front wheel side piping 23FL is opened to the hydraulic pressure supply side, and a return piping 32 where the fluid cylinder device 3 of the left front wheel side piping 23FL is connected to the return piping 32. It is possible to take three positions with the discharge position communicating with the In Figure 2,
The proportional flow control valve 9 is shown in the closed position. Further, the proportional flow rate control valve 9 includes pressure compensation valves 9a and 9.
The pressure compensating valves 9a, 9a allow the hydraulic pressure in the hydraulic chamber 3c of the fluid cylinder device 3 to reach a predetermined value when the proportional flow control valve 9 is in the supply position or the discharge position. It is designed to be preserved.

On the fluid cylinder device 3 side of the proportional flow control valve 9, a pilot pressure-responsive on-off valve 33 that can open and close the left front pipe 23FL is provided. When the solenoid valve 34 that guides the hydraulic pressure of the left front wheel side piping 23FL on the hydraulic pump 8 side of the proportional flow rate control valve 9 is opened, the hydraulic pressure of the solenoid valve 34 is introduced as pilot pressure into the on-off valve 33. When is equal to or greater than a predetermined value, the on-off valve 33 opens the left front wheel side pipe 23FL, allowing the proportional flow rate control valve 9 to control the flow rate of fluid to the fluid cylinder device 3.

Further, a relief valve 35 that opens when the hydraulic pressure in the hydraulic pressure chamber 3c of the fluid cylinder device 3 increases abnormally and returns the waterfall body in the hydraulic pressure chamber 3c to the return reaction 32, and an accumulator 2
It is connected to the discharge pipe 8a of the hydraulic pump 8 near the downstream side of the 2 connection part, opens when the ignition is turned off, returns the oil stored in the accumulator 22 to the reserve tank 29, and releases the high pressure state in the accumulator 22. A hydraulic pump that returns the pressure inside the hydraulic pump 8 to the reserve tank 29 to lower the oil discharge pressure of the hydraulic pump 8 when the discharge pressure of the hydraulic pump 8 increases abnormally. Return accumulators 38 and 38 are provided, respectively, which are connected to the relief valve 37 and the return pipe 32 and perform a pressure accumulation function when fluid is discharged from the fluid cylinder device 3.

3A and 3B show the control unit 17
This is the block diagram of the suspension characteristic control device in the vehicle.

In FIGS. 3A and 3B, the suspension characteristic control device provided in the control unit 17 according to the present embodiment includes vehicle height sensors 14, 14, 14 for each wheel.
and 14 vehicle height displacement signals XFR%XFL, XRR%
Control system A that controls the vehicle height to the target vehicle height based on XRL, and vehicle height displacement signals XFR, XFL% XIIR, XR
Vehicle height displacement speed l5 obtained by differentiating L 16 degree signal Y FR% Y FL% Y RIl% Y R
a control system B that suppresses the vehicle height displacement speed based on L;
A control system C that aims to reduce the vertical vibration of the vehicle based on the vertical acceleration signals GFRs GFL, G, of the vertical acceleration sensors 15, 15, and 15, and the branch pressure sensor 13 of each wheel.
, 13, 13, 13 pressure signal P FR% P FL%
It is comprised of a control system D that calculates the torsion of the vehicle body based on PRR%PRL and suppresses this.

The control system A includes outputs XFR, X. While adding L,
A bounce component compensator 40 that calculates the bounce component of the vehicle by adding the outputs XR and XRL of the vehicle height sensors 14 and 14 of the left and right rear wheels 2RL and 2RR, and a bounce component compensator 40 that calculates the bounce component of the vehicle;
From the sum of the outputs XFR and XFL of the R vehicle height sensors l4 and l4, the vehicle height sensors 14 of the left and right rear wheels 2RL and 2RR,
Output XRRs of l4 Pitch calculation unit 4l that calculates the pitch of the vehicle by subtracting the added value of XRL, output XF of vehicle height sensors 14, 14 of left and right front wheels 2PL, 2FR
RN XFt. The difference between XFRXFL and left and right rear wheels 2R
L, 2RR vehicle height sensor l4, l4 output XRR%
A roll component calculation unit 42 is provided that calculates the roll component of the vehicle by adding the RL difference XRR−XRL.

The control system A also calculates the bounce component of the vehicle calculated by the bounce component calculation section 40 and the target average vehicle height T. is input, and the pitch of the vehicle calculated by the bounce control unit 43 and pitch component calculation unit 41, which calculates the amount of fluid supplied to the fluid cylinder device 3 of each wheel in bounce control, is input based on the gain Kl11. , based on the gain KP1, the roll force and target roll displacement amount TR calculated by the pitch control section 44 and the roll component calculation section 42, which calculate the amount of fluid supplied to the fluid cylinder device 3 of each wheel in pitch control, are calculated manually. and gains KRF1, KR. ．． The vehicle is equipped with a roll control unit 45 that calculates the amount of material to be supplied to the fluid cylinder device 3 of each wheel in roll control based on the vehicle height corresponding to the target roll displacement amount TR.

In this way, each control 17 18 ? calculated by the bounce control section 43, pitch control section 44, and roll control section 45? is reversed for each wheel, that is, the vehicle height displacement signal X FR% X FL% X RR, X RL. detected by the vehicle height sensors l4, l4, l4, 14. is reversed so that the positive and negative values are reversed, and then the bounce, pitch, and roll control amounts for each wheel are added, respectively, and the flow rate signal to the proportional flow control valve 9 of each wheel in the control system A is QFRQ FL. l, QR
RI and QRLI are obtained.

In addition, each vehicle height sensor l4, l4, l4, 14, bounce calculation unit 40, pitch calculation unit 4l, and roll calculation unit 42
Dead band devices 70, 70, 70, 70 are provided between the vehicle height sensors 14, 14, 14, 14, and vehicle height displacement signals XFRs XFL, X Rll% XllL
is the preset dead zone XH, XH, XH,
These vehicle height displacement signals
sXFL. ．． XR? XRL, bounce calculation unit 40
, is output to the pitch calculation section 4l and the roll calculation section 42.

Control system B receives vehicle height displacement signals XFR%XF input from vehicle height sensors l4, 14, l4 and 14. R.R., X
By differentiating RL, the vehicle height displacement speed signal Y is obtained according to the following formula.
F? It has differentiators 46, 46, 46, and 4G that calculate Y FL% Y RR% Y RL.

Y= (X, -X..)/T Here, x4 is the amount of vehicle height displacement at time t, xn-1 is the amount of vehicle height displacement at time t-1, and T is the sampling link time.

Further, the control system B generates vehicle height displacement speed signals Y, . , Y. From the added value of R, the vehicle height displacement speed signal YII of the left and right rear wheels 2RL, 2RR side is obtained.
A pitch component calculation unit 47a that calculates the pitch component of the vehicle by subtracting the added values of L and YRR, and the left and right front wheels 2PL.
, the difference Y, R-YFL of the vehicle height displacement speed signal Y FL% Y FR on the 2PR side, and the difference YRR-YRL of the vehicle height displacement speed signal YRL, Y■ on the left and right rear wheels 2RL, 2RR side are added. It also includes a roll component calculation section 47b that calculates the roll component of the vehicle.

In this way, the pitch component calculated by the pitch component calculation unit 47a is inputted to the pitch control unit 48, and the gain K
l9 20 in pitch control based on P2? The flow rate control amount to the proportional flow control valve 9 is calculated, and
The pitch component calculated by the roll component calculation unit 47b is input to the roll control unit 49, and is
, KRR2, the flow control amount to each proportional flow control valve 9 in roll control is calculated.

Further, each control amount calculated by the pitch control section 48 and the roll control section 49 has its sign reversed for each wheel, that is, the vehicle height displacement speed calculated by the differentiators 46, 46, 46, 46. Signal YFR, Y FL% Y RR%
Y RL is reversed so that its positive and negative signs are opposite,
Thereafter, the pitch and roll control amounts for each wheel are respectively added, and the flow signals QFR■, QFL2, QFL2,
QRR2 and QRL2 are obtained.

The control system C includes a bounce calculation unit 50 that adds the outputs GFR%GFL%GR of the vertical acceleration sensors 15, 15, and 15 and calculates the bounce of the vehicle, and a bounce calculation unit 50 that calculates the bounce of the vehicle, and The sum of 1/2 of the outputs of the vertical acceleration sensors 15 and 15 installed above (G FR+
A pitch force calculation unit 51 calculates the pitch component of the vehicle by subtracting the output G11 of the vertical acceleration sensor 15 provided at the center of the left and right rear wheels in the vehicle width direction from GFL)/2; Output GF of vertical acceleration sensor l5 on the front wheel side
The calculated value of the bounce component calculated by the roll component calculation unit 52 and the bounce component calculation unit 50 that calculates the roll component of the vehicle by subtracting the output GFL of the vertical acceleration sensor l5 on the left front wheel side from R is input. , a calculated value of a certain pitch calculated by a bounce control unit 53 that calculates the control amount of fluid to each proportional flow control valve 9 in bounce control based on the gain KB3 and a pitch component calculation unit 51 is input, Based on the gain K p s, a pitch control unit 54 that calculates the amount of fluid to be controlled to the proportional flow rate control valve 9 in pitch control, and a pitch value calculated by the roll component calculation unit 52 are input. , gain KRF
3, a pitch control unit 5 that calculates the control amount of fluid to the proportional flow rate control valve 9 in pitch control based on KRR3;
4, and a roll control unit 21 22 and a control unit 55.

In this way, the bounce control section 53, the pitch control section 5
4 and the control amount calculated by the roll control unit 55, the positive and negative values are reversed for each wheel, and then the bounce, pitch, and roll control amounts for each wheel are added, and the control amount is output from the control system C. Flow rate signal Q to each proportional control valve 9 FR3, Q FL3・Q RR3 and Q
RL3 is obtained. Furthermore, the vertical acceleration sensors 15, 15
, l5, bounce component calculation section 50, pitch component calculation section 5
1 and the roll calculation unit 52, there is a dead band device 8.
0, 80, 80 are provided, and vertical acceleration sensors l5, 1
Vertical acceleration signal GFR% output from 5 and 15
G F L, GI+ are the preset dead zone
6, X6, and X6, the vertical acceleration signals GFR, G, and GR are bounced or divided into
, pitch component 7 calculation unit 5l and roll strength calculation unit 52
It is designed to output to .

The control system D receives fluid pressure detection signals from the fluid pressure sensors 13 and 13 of the fluid cylinder device 3 of the left and right front wheels 2FL and 2PR. PFLX
P■ is input, and the difference in hydraulic pressure between the hydraulic pressure chambers 3C and 3C of the fluid cylinder device 3 of the left and right front wheels 2PR and 2FL PFR P
Ratio P+ of FL and these added values PFR+PFL
(PFR PFL) / (PFR+PFL) is calculated, and if the calculated hydraulic pressure ratio P, is -ωL, < P l < ω, with respect to the threshold pressure ratio ω, then the calculated The hydraulic pressure ratio P1 is output as is, and on the other hand, P,
If <-ω, or P+>ω[, then the front wheel side 7 night pressure ratio calculation unit 60a outputs the threshold hydraulic pressure ratio of one or
The hydraulic pressure detection signal PRL%Pll is manually input from the hydraulic pressure sensors 13, 13 of the waterfall body cylinder device 3, and the left and right front wheels 2FR
, 2FL, the difference in hydraulic pressure between the hydraulic pressure chambers 3c and 3C of the fluid cylinder device 3 PRR PRI- and their added value P RIl
+ Ratio to PRL PR = (P+u+PRL) /
(PRR+PRL), and a rear wheel side hydraulic pressure ratio calculating section 60b that calculates the ratio PR of the rear wheel side hydraulic pressure using a gain ω.
Based on
, and the output of the warb control unit 60 is subtracted from the gain 23 24 ? Then, on the front wheel side, the gain ω6 is used to multiply by a predetermined value, and further, the fluid supply control amount to each wheel is adjusted so that the positive and negative values are opposite between the left and right wheels. is inverted, and the flow rate signals Q FR4, Q FLI, QRRI to each proportional flow control valve 9 in the control system D are
, QRLI is obtained.

Each control system A, B, C and D obtained as above
The flow rate signals to each proportional flow rate control valve 9 at are added for each wheel, and the final total flow rate signal to each proportional flow rate control valve 9 is obtained. QFL. QRR and QRL are obtained.

Table 1 shows an example of a control gain map used in each of the control systems A, B, C, and D stored in the control unit 17, and seven modes are set depending on the operating state. has been done.

In Table 1, Mode 1 is the value of each control gain for 60 seconds after the engine has stopped, and Mode 2 is ■, when the ignition switch is on but the vehicle is stopped and the vehicle speed is zero. The value of each control gain, mote 3, is the value of each control gain when the vehicle's lateral acceleration G exceeds 0.1, and the value of each control gain is 0 when the vehicle's lateral acceleration G exceeds 0.1. The value of each control gain in a slow turning state of .3 or less, mode 5 is the value of each control gain in a moderate turning state of 0.5 or less, where the lateral acceleration G5 of the vehicle exceeds 0.3, mode 6 is: The values of each control gain in a sharp turning state where the vehicle's lateral acceleration Gs exceeds 0.5 are shown, and mode 7 is set when the reverse roll mode is selected by the roll mode selection switch (not shown). , the lateral acceleration Gs of the vehicle is 0.

mode 4 in a slow turning state of 0.3 or less.
Instead, it shows the value of the control gain to be selected, and when the vehicle speed exceeds 120 km/h, the mode is automatically switched to mode 4 even if the reverse roll mode is selected. In Table 1, Q MA
It is set so that the fluid does not flow back into the accumulator 22 from the hydraulic pressure chamber 3C of the fluid 25 26 cylinder device 3, and
P MIN indicates the minimum pressure within the hydraulic pressure chamber 3c of the fluid cylinder device 3, and the pressure within the hydraulic pressure chamber 3c of the fluid cylinder device 3 may decrease excessively, causing the gas spring 5 to fully expand and be damaged. It is set to not. In Table 1, the arrow indicates that the control gain is set to the same value as the numerical value indicated by the arrow.

In Table 1, except for mode 7, each control gain is set such that the larger the mode number is, the more the suspension control is performed with emphasis on driving stability.

The control unit 17 performs suspension control by setting each control gain to the values shown in Table 1 depending on the driving condition. In this embodiment, when the driving condition changes, and as shown in Table 3,
Control is performed so that the value of each control gain is changed.

Table 2 shows the roll mode selection switch (not shown). Table 3 shows a method of controlling the setting change of each control gain value when the operating state changes when the forward roll mode is selected. This shows a method of controlling the setting changes of each control gain value when the operating state changes.

As shown in Table 2, when the normal roll mode is selected by the roll mode selection switch (not shown), the driving condition changes and the mode is changed to a mode in which suspension control with emphasis on ride comfort is to be performed. from,
When transitioning to a mode in which suspension control with emphasis on driving stability is to be performed, the control unit 17 immediately switches to the new mode, even if the change in driving conditions is large and the mode with the next number is skipped. Change the setting of each control gain to the control gain value,
It is designed to perform suspension control. Therefore, running stability is not impaired.

On the other hand, when the driving condition changes and the mode shifts from a mode in which suspension control with emphasis on driving safety is performed to a mode in which suspension control with emphasis on riding comfort is to be performed, the mi-control unit 17: For example, after the predetermined delay time shown in (d) in Table 2, each control gain is set to the control gain value of the new mode without immediately changing the setting to the control gain value of the new mode.
．． After a delay of 5 seconds, the control gain value is controlled so that the setting is changed to the control gain value of the mode with the smaller mode number.
In the case where the mode number is 1, the control gain is changed after the predetermined delay time (d).
Change the setting to the control gain value of the smaller mode, and
After a predetermined delay time (d), the setting is changed to the control gain value of the mode whose mode number is one smaller, and so on, each time the setting is changed to the control gain value of the mode whose mode number is one smaller. d) The settings of each control gain are changed with a delay. In this way, after the predetermined delay time (d), each control gain is controlled to be changed to the control gain value of the mode with the mode number one smaller, so the driver will not feel any discomfort. In addition, when the driving condition changes significantly and the mode skips over the mode with the next lower number, the driving condition does not become transiently unstable, and therefore the driver does not experience an unstable driving feeling. I have nothing to give.

In addition, when the operating state changes from mode 1 and shifts to another mode, be sure to shift to mode 2 first, and
When the operating condition changes from mode 2 and you want to move to another mode, you must first move to mode 3, and then
When transitioning to Mode 2 from an operating state of Mode 3 or higher, the transition must first be made to Mode 2, and when transitioning to Mode I, the transition must occur after passing through Mode 2.
Suspension control in modes 1 and 2 does not have the purpose of improving ride comfort or running stability, so when changing from mode 3 to mode 2 or from mode 2 to mode l, there is a predetermined time delay. Instead, it is sufficient to immediately change the setting of each control gain to the control gain value of that mote. Therefore, in Table 2, mote ■ and mote 2 are omitted.

In Table 3, the reverse roll mode is selected by a roll mote selection switch (not shown), and therefore mote 7 is used instead of mote 4. However, Mote 7 is not a mode with the purpose of improving ride comfort or driving stability, but is a reverse roll mode that emphasizes the driver's preference, so when switching from Mote 7 to another mode, must immediately switch to positive roll state, therefore, without delay, change the control gain to the control gain value of the other mote, and also change the control gain from mode 5 or mode 6 to mote 7.
When switching to mode 3 by skipping mode 7, each control gain is immediately changed to the control gain value of mode 3 after a predetermined delay time (d) without passing through mode 7. , or, after a predetermined delay time (d), each control gain is set to the control gain value of Mos 1 and 5, and further, after a predetermined delay time (d), each control gain is immediately changed to:
Control is performed to change the setting to the control gain value of mode 3.

As described above, according to this embodiment, when there is a transition from a driving state in which control should be performed with an emphasis on riding comfort to a driving state in which control should be performed with emphasis on driving stability to a driving state in which control should be performed in a manner that emphasizes ride comfort, Since each control gain is immediately changed to the control gain value of the mode in the new driving state, driving stability is not impaired, and it is also possible to change the setting of each control gain to the control gain value of the mode in the new driving state. When transitioning to a driving state where control with emphasis on ride comfort is performed, each control gain should be changed to
After a predetermined delay time, the setting is sequentially changed to the control gain value of the next mode, and even to the control gain value of the mode in the new driving state, so it does not give the driver a sense of discomfort or unstable driving. can be effectively prevented from giving.

The present invention is not limited to the above-mentioned examples, and various modifications can be made within the scope of the invention described in the claims, and these are also included within the scope of the present invention. It goes without saying that there is.

For example, in the embodiment described above, in the case of transitioning from a driving state in which control should be performed with an emphasis on driving stability to a driving state in which control should be performed in a manner that emphasizes riding comfort,
After a predetermined delay time, each control gain is sequentially changed to the control gain value of the next mode. If selected appropriately, it is not necessarily necessary to delay the predetermined time and sequentially change the setting to the control gain value of the next mode.

Furthermore, in the embodiment described above, the value of each control gain is changed according to the value of the lateral acceleration G8 applied to the vehicle, but the value of each control gain is set using other factors. It may be changed.

Further, in the embodiment, the lateral acceleration GS applied to the vehicle is calculated based on the steering angle detection signal detected by the steering angle sensor 18 and the vehicle speed detection signal detected by the vehicle speed sensor 19. According to the value of acceleration G3 of Control may be performed by detecting the acceleration Gs in the direction.

Furthermore, although the suspension device is equipped with the gas spring 5 in the above embodiment, the present invention can also be applied to a suspension device that does not include the gas spring 5.

Effects of the Invention According to the present invention, when the driving state changes from a driving state in which control should be performed with emphasis on driving stability to a driving state in which control should be performed with emphasis on ride comfort without impairing driving stability, the driver can It becomes possible to effectively prevent a feeling of discomfort or unstable driving from occurring.

33 34 Table 2 Table 3 36 37

[Brief explanation of the drawing]

FIG. 1 is an overall schematic diagram of a vehicle including a vehicle suspension device according to an embodiment of the present invention. FIG. 2 is a circuit diagram of a hydraulic circuit that supplies fluid from a hydraulic pump to a fluid cylinder device or discharges fluid therefrom. FIGS. 3A and 3B are block diagrams of the suspension characteristic controller within the control unit. 1...Vehicle body, 2FL...Left front wheel, 2FR...Left rear wheel,
2RL...right front wheel, 2RR...right front wheel, 3
...Fluid cylinder device, 3FL...Fluid cylinder device for left front wheel, 3FR...
Fluid cylinder device for right front wheel, 3RL...Fluid cylinder device for left rear wheel, 3RR...Fluid cylinder device for right rear wheel, 3a...Cylinder body, 3b...Piston, 3c...・Hydraulic pressure chamber, 3d・Piston rod, 4...Communication path, 4a, 4b, 4c, 4d...Branch communication path, 5...Gas spring, 5FL...Gas spring for left front wheel, 5FR・...Gas spring for right front wheel, 5RL...Gas spring for left rear wheel, 5RR...Gas spring for right rear wheel, 5a, 5b, 5c, 5d-Cass spring unit, 5e.
...Diaphragm, 5f...Gas chamber of gas spring, 5g...Hydraulic pressure chamber of gas spring, 8...Hydraulic pump, 8a...Discharge pipe, 9...
...Proportional flow control valve, 9a...Pressure compensation valve, 10...Fluid passage, 12.Discharge pressure gauge, 13.
・Hydraulic pressure sensor, 14. Vehicle height displacement sensor, 15.
... Vertical acceleration sensor, 17... Control unit, 18... Rudder angle sensor, 19... Vehicle speed sensor, 2
0... Drive source, 21... Hydraulic pump for power steering device, 38 39 2... Accumulation rake, 3F... Front wheel side piping, 23R... Rear wheel side piping, 3
FL...Left front wheel side piping, 3PR...Right front wheel side piping, 3RL...Left rear wheel side piping, 3RR...Right rear wheel side piping, 5a, 25b, 25c, 25d...Orifice, 6.
...Switching valve, 8...Unload relief valve, 9...Reserve tank, 3...Opening/closing valve, 34...Solenoid valve, 5...
Relief valve, 6... Ignition key series operating valve, 7... Hydraulic pump relief valve, 8... Return accumulator, 0... Pounce component calculation unit, l... Pitch component calculation unit, 2... Roll line segment calculation section, 3... Bounce control section, 4... Pitch control section, 40... Roll control section, ... Differentiator, a... Pitch certain calculation section, b...Roll component calculation section, ...Pitch control section, ...Roll control section, ...Pounce component calculation section, ...Pitch component calculation section, ...Roll line segment calculation section, ... - Bounce control section, ...Pitch control section, ...Roll control section, ...Wave control section, a...Front wheel side hydraulic pressure ratio calculation section, b...Rear wheel side hydraulic pressure ratio calculation section. 41

Claims (1)

[Claims] Each wheel has a fluid cylinder device between the sprung weight and unsprung weight of the vehicle, and controls the setting of control gains for suspension characteristics based on multiple modes depending on the vehicle driving condition. A suspension characteristic control means and a displacement detection means for detecting the displacement of the vehicle are provided, and the displacement of the vehicle is determined by a predetermined control gain set and controlled by the suspension characteristic control means based on the detection result of the displacement detection means. In an active suspension device that controls the amount of supply and discharge of working fluid to the fluid cylinder device so as to cancel the amount of working fluid supplied and discharged from the fluid cylinder device, the suspension characteristic control means determines whether the driving condition of the vehicle is adjusted based on the output of the driving condition detection means. When the driving state shifts from a driving state where control should be performed with emphasis on driving stability to a driving state where control with emphasis is placed on driving stability, the control gain is immediately set to the control gain of the mode corresponding to the new driving state. ,
On the other hand, when the driving state shifts from a driving state where control should be performed with emphasis on running stability to a driving state where control with emphasis on ride comfort is to be performed, the control gain is sequentially changed to the control gain of the next mode, A suspension device for a vehicle, characterized in that it is configured to change the setting of a control gain of a mode according to a new driving condition.