JPH03235710A - Suspension device for vehicle - Google Patents

Abstract

PURPOSE:To constantly ensure a preferable ride feeling and travel stability by providing a standard vehicle height adjusting means, and changing control gain for bump side and rebound side vehicle height variations according to standard vehicle height set with the said means. CONSTITUTION:In a suspension device, a hydraulic cylinder device 4 is interposed between a body 2 composing the above-spring part of a vehicle and the below-spring part including each of wheels 3FL - 3RR respectively. A suspension characteristic is varied by controlling oil supply and discharge fro individual upper and lower hydraulic chambers 4b and 4c of each hydraulic cylinder device 4. In this case, a standard vehicle height adjusting means, which can adjust and set a standard vehicle height, is provided to a control unit 10 controlling the control valve 8 according to a vehicle travel condition. Control gain for bump side and rebound side vehicle height variation is changed according to the standard vehicle height set with the said means.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a suspension device for a vehicle that can ensure favorable riding comfort and running stability. Supplying working fluid to a fluid cylinder device provided between
The present invention relates to an active suspension system for a vehicle that can control suspension characteristics by controlling the amount of exhaust, and that can ensure favorable ride comfort and driving stability.

Prior Art A suspension device called a passive suspension device, which has been widely used in the past, consists of a hydraulic shock absorber and a damper unit made of a spring such as a coil spring.By making the damping force of the hydraulic shock absorber variable, the suspension device is Although it is possible to adjust the characteristics to some extent, the range is small, and in practice, the suspension characteristics in 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,
Suspension devices called active suspension devices that can control suspension characteristics as desired have been proposed (Japanese Patent Publication No. 59-14365, Japanese Patent Application Laid-open No. 63-130418, etc.).

In this way, unlike passive suspension devices, active suspension devices have the advantage of being able to control the suspension characteristics as desired, but for some reason, the working fluid may leak out of the suspension device, etc. If a failure occurs in the suspension system and the suspension characteristics cannot be controlled,
In order to prevent sudden changes in vehicle height that would make the vehicle inoperable, the volume of the fluid cylinder device for each wheel is generally kept small and designed to prevent large stroke changes. .

Problems to be Solved by the Invention Therefore, in an active suspension device that allows the driver to arbitrarily set the reference vehicle height according to his/her preference, when the driver sets the reference vehicle height to a high value, , the control loaf for rebound becomes so small that during rebound the piston of the fluid cylinder device hits the top end of the cylinder and it is no longer possible to control the suspension.
On the other hand, when the reference vehicle height is set to a low value, the control stroke for bumps becomes extremely small, and when a bump occurs, the piston of the fluid cylinder device hits the lowest end of the cylinder, making it no longer possible to perform suspension control. There was a problem that the ride comfort and running stability deteriorated. This is a very serious problem, especially when driving on rough roads.

Purpose of the Invention The present invention provides a fluid cylinder device between an unsprung weight and an unsprung weight, and controls the supply and discharge amount of working fluid to this fluid cylinder device to change suspension characteristics. An object of the present invention is to provide an active suspension device for a vehicle that is capable of adjusting a reference vehicle height and that can ensure favorable ride comfort and running stability. .

Structure of the Invention The object of the present invention is to provide a reference vehicle height adjustment means that can adjust and set a reference vehicle height, and to adjust the bump side vehicle height according to the reference vehicle height set by the reference vehicle height adjustment means. This is achieved by providing a control gain control means that changes the control gain for the change and rebound side vehicle height change.

In a preferred embodiment of the present invention, when the reference vehicle height is set to a high value by the reference vehicle height adjustment means,
The control gain control means controls the control gain so that the control gain for bump side vehicle height changes is large and the control gain for rebound side vehicle height changes is small, and on the other hand, when the reference vehicle height is set to a low value. The control gain control means is configured to control the control gain so that the control gain for bump-side vehicle height changes is small and the control gain for rebound-side vehicle height changes is large.

In a further preferred embodiment of the present invention, the control gain control means is configured to control the control gain only when it is determined that the vehicle is traveling on a rough road.

Effect of the Invention According to the present invention, since the reference vehicle height adjustment means is provided, the reference vehicle height can be arbitrarily adjusted and set according to the driver's preference. Even when the height is set high or low, the control gain control means is provided to change the control gain for bump side vehicle height changes and rebound side vehicle height changes according to the set standard vehicle height, so that the standard vehicle height can be adjusted accordingly. As a result of the height adjustment, the control stroke for either the bump side vehicle height change or the rebound side vehicle height change decreases, and the piston of the fluid cylinder device hits the top or bottom end of the fluid cylinder device, making it impossible to control the suspension characteristics. Therefore, even if you adjust the reference vehicle height according to your preference,
It becomes possible to ensure desirable ride comfort and running stability.

In a preferred embodiment of the present invention, when the reference vehicle height is set to a high value by the reference vehicle height adjustment means, the control gain control means increases the control gain for the bump side vehicle height change, and increases the control gain for the bump side vehicle height change. The control gain is controlled so that the control gain for high changes is small, and on the other hand, when the reference vehicle height is set to a low value, the control gain control means is configured to reduce the control gain for bump side vehicle height changes, and for rebound Since the control gain is controlled to increase the control gain for side vehicle height changes, when the reference vehicle height is set to a high value, the piston of the fluid cylinder device is It is possible to reliably prevent the suspension characteristics from becoming uncontrollable if the device hits the upper end of the device, and if the standard vehicle height is set to a low value, the change in vehicle height on the bump side will prevent the fluid cylinder device from becoming uncontrollable. It is possible to reliably prevent the piston from hitting the lower end of the fluid cylinder device and causing the suspension characteristics to become uncontrollable.

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 an automobile equipped with a vehicle suspension device according to an embodiment of the present invention.

In FIG. 1, only the left-hand side of the motor vehicle is shown, but the right-hand side is similarly constructed. In FIG. 1, an automobile 1 includes a vehicle body 2 constituting a sprung portion of the vehicle, a left front wheel 3FL, a right front wheel 3FR (not shown),
The left rear wheel 3RL and the right rear wheel 3RR (not shown) are provided, and the left front wheel 3F1. and right front wheel 3FR and left rear wheel 3RL
The right rear wheel 3RR is supported by a wheel support member such as an axle (not shown), and the left front wheel 2PL is supported by a wheel support member such as an axle (not shown).
, right front wheel 2 Fil, left rear wheel 2RL and right rear wheel 2R
R and the wheel support member constitute an unsprung portion.

The vehicle body 2 constituting the sprung portion of the vehicle and each wheel 3F11
．． One hydraulic cylinder device 4 is provided for each wheel between the unsprung portion including 3FR, 3RL, and 3RR.

FIG. 2 is a block diagram showing a control system of a vehicle suspension device according to an embodiment of the present invention.
Only the hydraulic cylinder devices 4 of the three wheels 3FL, 3FR13RL, 311R are shown. As shown in FIG. 2, the hydraulic cylinder device 4 for each wheel includes a hydraulic cylinder 4a fixed to a wheel support member of each wheel, and a hydraulic cylinder 4a fixed to a wheel support member of each wheel.
The upper hydraulic chamber 4b and the lower hydraulic chamber 4c are fitted into the hydraulic cylinder 4a so as to be able to reciprocate while sliding within the hydraulic cylinder 4a.
A piston 4d forming a piston 4d. piston 4d
A piston rod 4e extending to the upper die is attached to the
The upper end of the piston rod 4e is connected to the vehicle body 2 via a load sensor 21 that detects the load F applied to the suspension device.

Further, the upper hydraulic chamber 4b and the lower hydraulic chamber 4c of the hydraulic cylinder device 4 communicate with an oil pump 6 and an oil tank 7 driven by an engine (not shown) via oil passages 5b and 5c, respectively. In the oil passages 5b and 5C between the oil pump 6 and the upper and lower hydraulic chambers 4b and 4c, there are control valves 8 that control the amount of oil supplied to and discharged from the upper and lower hydraulic chambers 4b and 4c. It is provided. This control valve 8 is
It is composed of a proportional control valve having three switching positions, and by PID controlling the switching positions of the proportional control valve, the supply and discharge amount of oil to the upper hydraulic chamber 4b and the lower hydraulic chamber 4C are controlled. ing.

The control valve 8 for the hydraulic cylinder device 4 of each wheel is
Each is configured to be controlled by a control unit 10, and the control unit 10 includes a load detection signal from a load sensor 11, a strobe detection signal from a stroke sensor 12 that detects the stroke of each hydraulic cylinder device 4, A vehicle speed detection signal from the vehicle speed sensor 13 that detects the vehicle speed V, a longitudinal acceleration detection signal from the longitudinal acceleration sensor 14 that detects the acceleration GFI applied to the vehicle body 2 in the longitudinal direction of the vehicle body, and a lateral acceleration GL applied to the vehicle body 2 in the lateral direction are detected. lateral acceleration detection signal from the lateral acceleration sensor 15, vertical acceleration G applied to the unsprung portion of each wheel
The vertical acceleration detection signal from the vertical acceleration sensor I6 that detects v, the switching signal from the mode lever switch I7 that switches the roll characteristic of the vehicle body when the vehicle turns between normal roll mode and reverse roll mode, and the driver's operation. A reference vehicle height adjustment signal from a reference vehicle height adjustment switch 18 is manually inputted so that a person can adjust the reference vehicle height according to his or her preference.

The stroke sensor 12 includes a sensor body 12a fixed to the vehicle body 2, and a movable part 12b fitted into the sensor body 12a so as to be movable in the vertical direction.The movable part 12b is connected to the hydraulic cylinder 4a of the hydraulic cylinder device 4. The movable part 12b is also vertically displaced in accordance with the vertical movement of the hydraulic cylinder 4a, and by detecting this displacement amount, the stroke of each wheel is detected. It is configured.

FIG. 3 is a block diagram of a control system that controls the control gain according to the reference vehicle height installed in the control unit 10.

In FIG. 3, the control gain control system of the control unit 10 includes a steering wheel calculation means 20 that calculates the stroke of each wheel 3FL, 3FR13RL, and 3RR and outputs a control signal to the control valve 8, and a reference vehicle height Adjustment switch 1
a reference vehicle height setting means 21 that sets a reference vehicle height according to a reference vehicle height adjustment signal from 8 and outputs the reference vehicle height setting signal to a slope calculation means 20; and each wheel determined experimentally in advance. An initial value storage means 22 stores the initial stroke setting value and the initial load setting value of each wheel, and outputs the initial stroke setting value and the initial load setting value of each wheel to the stroke calculation means 20 at the time of starting. has been done.

The stroke calculation means 20 includes each wheel 3 FL.

3FR, 3RL, 3RR load detection signal from load sensor 11, stroke detection signal from each stroke sensor 12, vehicle speed detection signal from vehicle speed sensor 13, longitudinal acceleration detection signal from longitudinal acceleration sensor 14, lateral acceleration sensor The lateral acceleration detection signal from the vertical acceleration sensor 15, the vertical acceleration detection signal from the vertical acceleration sensor 16, and the switching signal from the roll mode lever switch 17 are each manually inputted, and based on these input signals, the stroke calculation means 2
0 is each wheel 3 FL, 3 FR according to the following formula
, 3RL, 3RR stroke XFL%XFl, X I
ILSX ill is calculated, a control signal is sent to the control valve 8, and the switching position of the control valve 8, which is a proportional control valve, is PID controlled, thereby controlling the oil to the upper hydraulic chamber 4b and the lower hydraulic chamber 4C. Control supply and emissions.

XFL=XO+ (Fo -F) /+αp+, +D
GXFl=X11 + (FoF) /
K+ α pi 10 GXIL=XO+ (Fo−
F)/to+αlL+DGXuw=Xo + (Fo −
F) /to+(Z++a+DG here, αFL= Ka' Gpa+K b-GL KC
−Gyαp*= Ka + Gpi Kb−Gt
Kc HGyα1t=Ka-GFRK b-GL
KC-Gvα,=Ka-GFl+Kb-GL-KC-G
v and KaSKbSKc are constants,
DG is a control gain correction amount associated with standard vehicle height adjustment.

FIG. 4 is a flowchart of suspension characteristic control of the active suspension device according to the embodiment of the present invention.

In FIG. 4, first, the initial value X of each wheel is stored in the initial value storage means 22. and the initial load setting value F. However, a reference vehicle height setting signal is also input from the reference vehicle height setting means 21 to the stroke calculation means 20, respectively.

Next, a load detection signal from each load sensor 11, a stroke detection signal from each stroke sensor 12, a vehicle speed detection signal from the vehicle speed sensor 13, a longitudinal acceleration detection signal from the longitudinal acceleration sensor 14, and a lateral acceleration from the lateral acceleration sensor 15. The detection signal, the vertical acceleration detection signal from the vertical acceleration sensor 16, and the switching signal from the roll mode lever switch 17 are manually input to the calculation means 20, respectively.

Thereafter, based on the stroke detection signals from each stroke sensor 12, the vertical acceleration detection signal from the vertical acceleration sensor 16, and the like, the rolling calculation means 20 determines whether or not the road is rough.

As a result, when it is determined that the road is not rough, the stroke calculating means 20 calculates the stroke of each wheel 3FL, 3FR, 3RL, 3RR xp+-1X PR% % X am
is calculated and a control signal is output to the control valve 8.

On the other hand, when it is determined that the road is rough, the stroke calculation means 20 further determines whether the reference vehicle height is set high.

As a result, when it is determined that the reference vehicle height has been adjusted by the driver and set higher than the standard vehicle height, the stroke calculation means 20 sets G←−K g −GL and performs the above-mentioned According to the formula, each wheel 3FL, 3
FR, 3RL, 3 RR stroke X FL%
X FII% X R17 and XRII are calculated and a control signal is output to the control valve 8.

On the other hand, when determining that the reference vehicle height is not set higher than the standard vehicle height, the stroke calculation means 20 further determines whether the reference vehicle height is set lower than the standard vehicle height. do.

As a result, when it is determined that the reference vehicle height is set lower than the standard vehicle height, the stroke calculation means 20 sets DG←K g−G +− and calculates each wheel 3F17 according to the above formula. .3
F[), 3RL, 3RR stroke X FL% X
FR%XRLsXllll is calculated and a control signal is output to the control valve 8.

On the other hand, when it is determined that the reference vehicle height is not set lower than the standard vehicle height, the reference vehicle height is considered to be equal to the standard vehicle height, so the stroke height calculating means 20
As DG=O, each wheel 3 according to the above formula
FL, 3 FR, 3RL, 3RR stroke XF1
．． , X PiSX ILSX R1 are calculated and a control signal is sent to the control valve 8.

According to this embodiment, when the reference vehicle height is set higher than the standard vehicle height, the control gain control means 20 corrects the control gain to be smaller, and therefore the upward movement of the piston 4d For, the control stroke is small and for the downward movement! -, the control stroke becomes large, so the piston 4d hits the upper end of the hydraulic cylinder 4a and the control becomes impossible. On the other hand, when the reference vehicle height is set lower than the standard vehicle height, is corrected by the control gain control means 20 so that the control gain becomes larger, so that the piston 4
For the downward movement of d, the control stroke is small, and for the upward movement, the control stroke is large, ensuring that the piston 4d hits the lower end of the hydraulic cylinder 4a and becomes uncontrollable. It becomes possible to prevent

The present invention is not limited to the above-mentioned examples, but 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. Needless to say.

For example, in the embodiment described above, the control gain control means 20 performs control gain correction control only when it is determined that the road is rough, but the reference vehicle height is set to be different from the standard vehicle height. When this occurs, the control gain control means 20 may always perform control gain correction control.

Furthermore, in the present invention, each means does not necessarily mean only physical means, but also includes cases where the functions are realized by software.

Effects of the Invention According to the present invention, it is possible to obtain an active suspension device for a vehicle that can arbitrarily adjust the reference vehicle height and ensure desirable riding comfort and running stability.

[Brief explanation of drawings]

FIG. 1 is an overall schematic diagram of an automobile equipped with a vehicle suspension device according to an embodiment of the present invention. Figure 2 shows
1 is a block diagram illustrating a control system of a vehicle suspension device according to an embodiment of the present invention. FIG. 3 is a block diagram of a control system for controlling control gains according to an embodiment of the present invention. FIG. 4 is a flowchart of suspension characteristic control of the active suspension device according to the embodiment of the present invention. 1...Automobile, 2...Vehicle body, 3FL...Left front wheel, 3RL...
...Left rear wheel, 4...Hydraulic cylinder device, 4a...Hydraulic cylinder, 4b...Upper hydraulic chamber, 4c...Lower hydraulic chamber, 4d... Piston, 4e... Piston rod, 5bs5c... Oil passage, 6... Oil pump, 7... Oil tank, 8 ...Control valve, 0...Control unit, ■...
Load sensor, 2... Stroke sensor, 3... Vehicle speed sensor, 4... Longitudinal acceleration sensor, 5... Lateral acceleration sensor, 6... ...Vertical acceleration sensor, 7...Roll mode lever switch, 8...
... Reference vehicle height adjustment switch, 0 ... Stroke calculation means, 1 ... Reference vehicle height setting means, 2 ... Initial value storage means. Figure 4

Claims (1)

[Claims] A fluid cylinder device is provided between the sprung mass and the unsprung mass, and a working fluid is supplied to the fluid cylinder device;
In an active suspension system for a vehicle that can change suspension characteristics by controlling emissions, there is provided a reference vehicle height adjustment means that can adjust and set a reference vehicle height, and a reference vehicle height adjustment means that can set a reference vehicle height. A suspension device for a vehicle, comprising control gain control means for changing control gains for bump-side vehicle height changes and rebound-side vehicle height changes in accordance with a reference vehicle height determined by the vehicle.