JP2584000Y2 - Vehicle suspension control device - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a suspension control device for a vehicle, and more particularly, to a posture control technology when rolling, pitching, or the like occurs in a vehicle.

[0002]

2. Description of the Related Art A typical vehicle suspension device is:
It is configured to combine a suspension spring and a shock absorber so that a predetermined spring action and a buffer action work.
In this case, the suspension characteristics are substantially constant. However, the required suspension characteristics vary depending on operating conditions, and so-called active suspension devices have been proposed to meet this requirement (for example, Japanese Utility Model Application No. 2-27922, Japanese Utility Model Application No. 2-28931 and See Japanese Utility Model Laid-Open No. 2-212).

[0003] In this method, an axle on which wheels are mounted is supported on a vehicle body via a hydraulic cylinder, and an actual stroke of the hydraulic cylinder is detected based on a relative displacement between the vehicle body and the axle, which changes according to a running state, and a target is detected. The vehicle height is adjusted by controlling the flow rate of hydraulic oil supplied to the hydraulic cylinder so that the hydraulic cylinder is expanded and contracted so as to match the stroke.

For example, when a vehicle body undergoes lateral acceleration or longitudinal acceleration during curve running or acceleration / deceleration, and this causes a change in posture such as rolling or pitching of the vehicle body, the change in posture is detected by a stroke sensor. According to the deviation between the detected stroke value and the target stroke value, the supply of hydraulic oil to the hydraulic cylinder is controlled so as to reduce the change in posture.

[0005]

However, in the conventional active suspension system, since the target stroke value corresponding to the lateral acceleration and the longitudinal acceleration is fixed, the roll characteristics and the pitch characteristics are changed according to the driver's preference. There is a problem that is difficult. An active suspension system capable of changing the roll characteristics and the pitch characteristics according to the driver's preference is disclosed in Japanese Utility Model Application Laid-Open No. 61-193.
However, there is a problem that the mathematical model for setting the target stroke proposed here is complicated and the calculation becomes complicated.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and provides a vehicle suspension control device that can easily change a posture control characteristic by simplifying a mathematical model for setting a target stroke. With the goal.

[0007]

SUMMARY OF THE INVENTION For this reason, the present invention detects a deviation between an actual stroke, in which a relative displacement between sprung and unsprung, of a vehicle is detected, and a target stroke, and adjusts the vehicle so as to coincide with the target stroke. A vehicle suspension control device for adjusting the vehicle height of the vehicle, a relative displacement detecting means for detecting a relative displacement between sprung and unsprung, an acceleration detecting means for detecting an acceleration generated in the vehicle, and detecting an acceleration generated in the vehicle an acceleration detecting means, the moment the center position when the moment is generated in the vehicle based on the acceleration generated in the vehicle
On the other hand, the acceleration according to a mathematical model representing a change in the attitude of the vehicle body set in advance based on a virtual mass equivalent to the actual vehicle mass imagined at an arbitrary distance from the moment center on the opposite side of the actual vehicle mass position. Target stroke calculating means for calculating a target stroke corresponding to the detection value of the detecting means, and controlling the vehicle height adjusting means so that the detected stroke of the relative displacement detecting means coincides with the target stroke calculated by the target stroke calculating means. and control means for, before
Arbitrary setting of the distance from the moment center to the virtual mass
The target stroke calculated by the target stroke calculating means.
And target stroke setting means capable of variably setting the stroke . Also, the relative displacement between the sprung and unsprung vehicle
The deviation between the actual stroke and the target stroke
And adjust the vehicle height to match the target stroke.
In the vehicle suspension control device to be adjusted, the spring
Relative displacement detection means for detecting relative displacement between upper and unsprung
And acceleration detection means for detecting acceleration generated in the vehicle;
Moment is generated in the vehicle based on the acceleration generated in the vehicle
Of the actual vehicle mass relative to the moment center position when
Any distance from the moment center opposite to the position
Based on the virtual mass equivalent to the virtual vehicle mass
According to a mathematical model that represents the body posture change that has been set in advance.
And suspension suspension control and damper control
The eye corresponding to the detection value of the acceleration detecting means, taking into account
A target stroke calculating means for calculating a target stroke;
To the target stroke calculated by the target stroke calculation means
The detection strokes of the relative displacement detection means match.
Control means for controlling the vehicle height adjusting means;
Set the distance from the center to the virtual mass as desired
Variable setting of the target stroke calculated by the stroke calculation means
And a settable target stroke setting means.

[0008]

[Action] In such a configuration, the actual vehicle mass position for the moment center position when the moment is generated in the vehicle based on acceleration generated on the vehicle side opposite moment <br/> bets from the center of any distance Position equal to the actual vehicle mass
Using a mathematical model obtained by imagining virtual mass ,
By changing the distance setting between the virtual mass and the moment center by the troke setting means , the roll angle and the pitch angle can be set arbitrarily, the calculation of the target stroke is easy, and the desired attitude control characteristics can be obtained. Can be easily obtained. Further, the target stroke calculating means is:
The suspension spring control and damper control are also taken into account.
Calculating the target stroke to increase control accuracy
Can be improved.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. In FIG. 1 showing the configuration of this embodiment, a wheel 1 is supported on a vehicle body 4 by a hydraulic cylinder 3 via an axle 2. The oil chamber 3a of the hydraulic cylinder 3 is connected via a flow control valve 5 to a hydraulic supply unit 6 composed of a pump, a tank and the like. The flow control valve 5 includes a servo amplifier 7
The amount of oil supply / discharge to / from the hydraulic cylinder 3 is controlled according to the output of the hydraulic cylinder 3. The servo amplifier 7 is provided in parallel with the hydraulic cylinder 3 and has an actual stroke from a stroke sensor 8 as a relative displacement detecting means for detecting a relative displacement between a vehicle body (spring-up) and an axle (unsprung), and a control unit 9 described later. And outputs a drive signal corresponding to the deviation to the flow control valve 5.

[0010] Other components except the control unit 9 and the hydraulic supply unit 6 are provided for each wheel. The control unit 9 controls the actual stroke from the stroke sensor 8, the pressure of the oil chamber 3a from the pressure sensor 10, the lateral acceleration of the vehicle from the lateral G sensor 11, the vehicle longitudinal acceleration from the longitudinal G sensor 12, and Eye
Outputs of the target roll height and the target pitch height from the target roll height setting device 13 for setting the roll characteristics and the pitch characteristics, which are the target stroke setting means, are input. The target stroke is calculated by a predetermined calculation formula described later on the basis of the equation (1) and is output to the servo amplifier 7.

As shown in FIG. 2, the control unit 9 converts the output of the pressure sensor 10 into a pressure signal and inputs the pressure signal. The control unit 9 converts the output of the stroke sensor 8 into a stroke signal and inputs it. Stroke signal input means 22, stroke speed calculation means 23 for calculating a displacement speed from the stroke signal, and lateral acceleration signal input means 24 for converting the output of the lateral G sensor 11 into a lateral acceleration signal and inputting it.
A longitudinal acceleration signal input means 25 for converting the output of the longitudinal G sensor 12 into a longitudinal acceleration signal and inputting it;
A reference stroke setting means 26 for setting a reference stroke in the standard state, a reference pressure setting means 27 for similarly setting a reference pressure, a simulated spring constant setting means 28 for setting a simulated spring constant and a damping coefficient of the hydraulic suspension, and A coefficient setting means 29, a target stroke calculating means 30 for calculating a target stroke as described later based on these signals and the signals from the roll height setting device 13 and the pitch height setting device 14, and a calculated target Target stroke output means 31 for outputting an output corresponding to the stroke to the servo amplifier 7;

Here, the roll control of this embodiment will be described. In FIG. 3, when a virtual mass m (shown by a broken line in the drawing) is considered at a position of a distance H _r ′ opposite to a sprung mass m at a position of a distance H _r from the roll center RC, the roll in a steady state is considered. The balance of the moment about the center RC can be expressed by the following equation. −2 · S ² · K · θ _r + m · β · H _r −m · β · H _r ′ = 0-(1) where, S: distance between RC and suspension, K: suspension spring constant, θ
_r : roll angle, β: lateral acceleration.

Accordingly, the steady roll angle θ _r is given by the following equation, and the distance H _r ′ from the roll center RC to the virtual mass is obtained.
The arbitrarily set the roll angle theta _r with respect to the lateral acceleration β by changing the. _{θ r = m · β · (} H r - H r ') / (2 · S 2 · K) - (2) where, in order to realize a hydraulic cylinder provided with a moment force by the virtual mass m in suspension It can be seen from the equation (1) that the force F generated by the hydraulic cylinder should be set as in the following equation.

F = (m · β · H _r ′ ) / (2 · S) − (3) Then, if the position control is performed as in the present embodiment, the target stroke y _R is given by the following equation (3). It can be given by an expression. y _R = F / K _m = (m · β · H _r ′ ) / (2 · S · K _m ) − (4) where K _{m is a} simulated spring constant.

Thus, the target stroke can be arbitrarily set by changing the distance H _r ' from the roll center RC to the virtual mass. The two-wheel model has been described above. In the case of four wheels, as shown in FIG. 4, the ratio of the distances L _f and L _r from the center of gravity CG of the vehicle to the roll centers RC of the front wheels and the rear wheels is calculated. Considering the equivalent mass (shown by a broken line in the figure) given by the following equation for each of the front and rear axes, and replacing these masses m _f and _mr with m in the above equation (4),
Each axis can be individually controlled in the same manner as in the case of two wheels.

M _f = (L _r · m) / (L _f + L _r ) ───── (5) m _r = (L _f · m) / (L _f + L _r ) ───── (6) In the drawing, S _f and S _r are the distance between the roll center and the suspension of the front and rear wheels, and K _f and K _r are the suspension spring constants of the front and rear wheels.
Note that the torque around the roll center RC due to the torsion of the frame is not considered, assuming that the front and rear roll angles are basically the same.

The pitch control is the same as that of the roll control if the longitudinal acceleration is α, the distance between the pitch center and the virtual mass is H _P ′, and the distance between the pitch center and the suspension is L. , The target stroke y _P can be given by the following equation. y _P = (m · α · H _P ′) / (2 · L · K _m ) ─── (7) Next, the control operation of the suspension control device of the present embodiment will be described with reference to the flowchart of FIG. .

First, in step 1, the pressure signal P, stroke signal y, lateral acceleration β, longitudinal acceleration α
Read. In step 2, the actual displacement obtained from the difference between the stroke y and the reference stroke y ₀ (y-y ₀₎ by differentiating the y '= d (y-y 0) / dt as a displacement velocity y' read calculate.

In step 3, the simulated spring constant K _m and the simulated damping coefficient C _m are set, and the target roll height H _r 'and the target pitch height H _P ' are set by the setting units 13 and 14, respectively. In step 4, based on each input detection value and set value,
The target stroke value Y is calculated by calculating and adding the spring control component, the damping control component, and the roll control component and the pitch control component according to the above-described formulas.

Y = [y ₀ − [(P−P ₀ ) · A / K _m ] − (C _m · y ′ / K _m )] ± [(m · β · H _r ′ ) / (2 · S · K _m )] ± [(m · α · H _P ′) / (2 · L · K _m )] Here, assuming that the effective sectional area of the hydraulic cylinder 3 is A, the pressure P at that time and the reference pressure P ₀ (P-P ₀ ) multiplied by the cross-sectional area A is the load variation, which is divided by the simulated spring constant K _m , that is, (P-P ₀ ) A / K
_m is the stroke amount (spring control amount) to be displaced in accordance with the load variation. Further, a damping stroke amount (damper control amount) is obtained as C _m · y ′ / K _{m from} the simulated damping coefficient and the hydraulic cylinder displacement speed. Target stroke caused by these springs control component and the damper control amount is that the reference stroke y ₀ minus these stroke, _{i.e., y 0 - (P-P} 0) · A / K m -C m ·
is obtained as y '/ K _m. Then, the target stroke Y is calculated by adding the roll control amount and the pitch control amount to the target stroke amount.

In the equation for calculating the target stroke Y, the sign of the roll control differs for the left and right wheels, and the sign of the pitch control differs for the front and rear wheels. Step 5
Then, a signal corresponding to the target stroke Y calculated in step 4 is output to the servo amplifier 7. Servo amplifier 7
Then, the target stroke Y output from the control unit 9 is compared with the actual stroke from the stroke sensor 8, and the flow control valve 5 for each wheel is drive-controlled so that the actual stroke matches the target stroke Y. The supply and discharge amount of hydraulic oil to and from the corresponding hydraulic cylinder 3 is adjusted.

According to such a configuration, the target stroke Y at the same acceleration is changed by changing the H _r ' in the term of the roll control and the H _P ' in the term of the pitch control by the setting devices 13 and 14. it can. In other words, the roll angle and the pitch angle generated by the same acceleration can be changed. Therefore, the roll characteristics and the pitch characteristics can be arbitrarily changed according to the driver's preference. Further, the calculation formula for setting the target stroke is simple, and the calculation of the target stroke can be easily performed.

In the present embodiment, the hydraulic cylinder is supported only by the hydraulic cylinder. However, an auxiliary spring or an auxiliary damper may be provided. Further, in this embodiment, the spring control and the damper control are also included, but these may be only the roll control and the pitch control which are not provided by other methods, or only one of the roll control and the pitch control. Good.

[0024]

According to the present invention as described above, according to the invention], mode
Virtual vehicle on the opposite side of the vehicle mass from the center of the
Use a mathematical model based on virtual mass equivalent to mass
In this way, the target stroke can be set using a simple calculation formula , and the moment
Driver only changes the distance setting from to the virtual mass
In, it is possible to freely change the roll characteristics and pitch characteristics depending favorite driver.

[Brief description of the drawings]

FIG. 1 is a block diagram of an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a control unit of the embodiment.

FIG. 3 shows a target stroke setting mathematical expression model according to the present embodiment.
Illustration for wheel

FIG. 4 is an explanatory diagram when the target stroke setting formula model is extended to four wheels.

FIG. 5 is a flowchart of a target stroke setting operation according to the embodiment.

[Explanation of symbols]

 2 Axle 3 Hydraulic cylinder 4 Body 5 Flow control valve 6 Hydraulic supply unit 7 Servo amplifier 8 Stroke sensor 9 Control unit 10 Pressure sensor 11 Lateral G sensor 12 Front and rear G sensor

Continuation of front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B60G 17/015

Claims (2)

(57) [Scope of request for utility model registration] 1. A suspension control for a vehicle for detecting a deviation between an actual stroke and a target stroke in which a relative displacement between a sprung portion and a unsprung portion of the vehicle is detected, and adjusting a vehicle height of the vehicle so as to match the target stroke. In the device, relative displacement detecting means for detecting relative displacement between sprung and unsprung, acceleration detecting means for detecting acceleration generated in the vehicle, and moment center when a moment is generated in the vehicle based on the acceleration generated in the vehicle Position of the actual vehicle mass relative to the position
A target corresponding to the detected value of the acceleration detecting means in accordance with a mathematical model representing a change in attitude of the vehicle body set in advance based on a virtual mass equivalent to the actual vehicle mass imagined at an arbitrary distance from the opposite moment center. a target stroke calculating means for calculating a stroke, and control means for controlling the vehicle height adjustment means such that the detected stroke of the relative displacement detecting means to the target stroke calculated by the target stroke calculation means matches, from the moment the center Virtual mass
Arbitrarily set the distance to
Target stroke that can variably set the target stroke calculated in steps
A suspension control device for a vehicle, comprising: a lock setting unit . 2. A relative displacement between a sprung portion and a unsprung portion of a vehicle is detected.
The deviation between the actual stroke and the target stroke
Adjust the vehicle height to match the target stroke
Vehicle suspension control device,
A relative displacement detecting means for detecting a relative displacement between unsprung parts;
An acceleration detecting means for detecting acceleration occurring in both,
When a moment is generated in the vehicle based on the resulting acceleration
Of the actual vehicle mass with respect to the moment center position of
Virtually located at an arbitrary distance from the opposite moment center
Based on the virtual mass equivalent to the actual vehicle mass
According to a mathematical model representing the set attitude change of the vehicle body, and
In addition, the suspension spring control and damper control
The target strike corresponding to the detection value of the acceleration detection means.
Target stroke calculating means for calculating the stroke,
The target stroke calculated by the trooke calculation means
Vehicle height so that the detection stroke of the displacement detection means matches
Control means for controlling the adjusting means;
Arbitrarily set the distance from
Variable setting of the target stroke calculated by the stroke calculation means
Special target stroke setting means.
Sign Vehicle suspension control system.