JPH07228124A - Stabilizer device of vehicle - Google Patents

Abstract

PURPOSE:To reduce the roll of a vehicle body naturally by computing the predicted value of lateral acceleration from the detected signals of driving speed and a steering angle, and control pressure corresponding to the value, converting it into a control signal to the pressure control valve of a hydraulic cylinder, discriminating the operating direction of a directional control valve, and outputting it to the pressure control valve. CONSTITUTION:The predicted value of lateral acceleration from the detected signals of vehicle speed and steering angle, and control pressure corresponding to the predicted value are computed, and a pressure control valve (b) receives a control signal corresponding to the computed value to adjust supply pressure to a hydraulic cylinder (a). A directional control valve (c) switches the flow of supply pressure in the discriminating direction based on the predicted value of lateral acceleration. As a result, the hydraulic cylinder (a) receives supply pressure at a single chamber through the directional control valve (c) from the pressure control valve (b), and operates to the expanding or contracting side while relieving oil pressure from a chamber on the opposite side, so that a moment in the opposite direction to the roll of a vehicle body is generated at a stabilizer bar to reduce the roll angle of the vehicle body actively, so it is possible to return the cylinder to its neutral position timely.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle stabilizer device.

[0002]

2. Description of the Related Art A stabilizer device is often adopted as a means for supplementing the roll rigidity of a suspension spring with a bar material of spring steel in order to suppress rolling of a vehicle body and improve running stability (Japanese Utility Model Publication No. 63-104105). , Actual Kaisho 63-15580
No. 8, Japanese Utility Model Publication No. 2-121409, etc.).

Of these, for the purpose of positively reducing the roll of the vehicle body, as shown in FIG. 13, both ends of the stabilizer bar 51 are supported by a frame via cylinders 52, 53 of a single rod type. There is proposed a system in which 53 is connected by hydraulic pipes 66, 67 and the operation of the cylinders 52, 53 is controlled by using a direction switching valve 68 (Japanese Utility Model Publication No. 63-82613).

When the directional control valve 68 is switched to, for example, the parallel active position P ₃ , the hydraulic pressure from the pump 69 flows to the cylinder 53 on one side and enters into the chamber 64 on the rod side thereof, and the piston rod 59 is operated to the compression side. As a result, the head side chamber 63 contracts while allowing the hydraulic pressure to escape, and the hydraulic pressure flows to the cylinder 52 on the opposite side and enters the head side chamber 61 to actuate the piston rod 58 to the extending side. The chamber 62 of the reservoir 70 stores the hydraulic pressure.
Shrink while escaping.

As described above, by switching the direction switching valve 68 to the active position P ₁ which crosses the parallel active position P ₃ in accordance with the turning direction of the vehicle, the cylinder 52 or 53 on one side operates to the extension side. Accordingly, the cylinder 53 or 52 on the opposite side operates toward the contraction side, so that the stabilizer bar 51 can be twisted to generate a moment opposite to the roll of the vehicle body.

In addition to the parallel and cross active positions P ₃ and P ₁ , the directional control valve includes a lock position P ₂ which shuts off the hydraulic circuits 65 and 66 on the cylinders 52 and 53 side at their neutral positions. Therefore, the active stabilizer function and the normal stabilizer function can be selectively exerted.

[0007]

However, in this prior art example, since the flow of the supply pressure to the cylinder is controlled only by the directional control valve, the stabilizer bar is naturally shaped according to the lateral acceleration accompanying the turning of the vehicle. It is difficult to generate a reverse roll moment, and there is also the possibility that the cylinder will not return to the neutral position easily even when the vehicle turns from the turning state to the straight-ahead state, and that the vehicle will run with the vehicle rolled.

The present invention aims to solve such problems.

[0009]

According to the first invention, FIG.
A hydraulic cylinder a that supports the end of the stabilizer bar, a pressure control valve b that adjusts the supply pressure to the hydraulic cylinder, and a direction switching valve c that switches the supply pressure flow between the expansion side and the compression side of the cylinder. , Means d for detecting the traveling speed of the vehicle
A means e for detecting the steering angle of the front wheels, a means f for calculating a predicted value of lateral acceleration from these detection signals, a means g for calculating a control pressure according to the predicted value, and a pressure control for the calculated value. A means h for converting and outputting the control signal to the valve, a means i for similarly determining the operating direction of the directional control valve based on the predicted value, and a means for outputting a control signal corresponding to the determination to the directional control valve. j and.

In the second invention, as shown in FIG. 12, means 1 for detecting the load on each wheel and means k for correcting the predicted lateral acceleration value based on these detection signals are added.

[0011]

According to the first aspect of the invention, the predicted value of the lateral acceleration and the control pressure corresponding to the predicted value are calculated from the detection signals of the vehicle speed and the steering angle, and the pressure control valve controls the control signal corresponding to the calculated value. In response to this, the supply pressure to the cylinder is adjusted. Further, the direction switching valve switches the flow of the supply pressure in the determination direction based on the predicted lateral acceleration value.

Therefore, the cylinder receives the supply pressure from the pressure control valve to the chamber on one side through the directional control valve and operates toward the expansion side or the contraction side while escaping the hydraulic pressure from the chamber on the other side. It is possible to generate a moment in the opposite direction and actively reduce the roll angle of the vehicle body.

In this case, the reverse moment acts on the stabilizer bar with a first-order lag in the same manner as the actual lateral acceleration, based on the predicted value of the lateral acceleration, so that the roll of the vehicle body is suppressed in a natural manner with high precision. It is also possible to accurately return the cylinder to the neutral position.

According to the second aspect of the present invention, since the predicted value of the lateral acceleration is corrected from the detected load of each wheel, the proper active characteristic according to the actual tire cornering power is obtained even if the vehicle loading amount changes. Can be secured.

[0015]

First, the principle of the present invention will be described with reference to FIG.
In order to support the vehicle body on the axle like this, suspension bar SPR, shock absorber S / ABS, and stabilizer bar STAB are provided. Stabilizer bar ST
The AB is attached to the axle bracket as a torsion bar at its center. Both ends of the bar STAB are connected to the vehicle body side, and an actuator ACTR is added to one side thereof.

When the lateral acceleration α acts on the mass m of the vehicle body,
The vehicle body tries to roll to the opposite side centering on the roll center. At that time, the CPU controls the actuation of the actuator ACTR according to the lateral acceleration α, so that the stabilizer bar ST
When a moment is generated in AB in the direction opposite to the roll of the vehicle body, the roll angle θ of the vehicle body can be reduced to a small value. Kst in the figure
Represents the spring constant of the suspension spring SPR, Kst represents the spring constant of the stabilizer bar STAB, and Cs represents the damping coefficient of the shock absorber.

[0017] simplify this equivalent model of the roll single degree of freedom, the vehicle body roll moment of inertia I _Z as in FIG. 2
Rigidity of suspension spring as bearing force of Gsp
, Stability of stabilizer bar Gst and damping resistance of shock absorber C _R work. When the actuator ACTR of the stabilizer bar is operated in the direction opposite to the lateral acceleration α under the control of the CPU, the roll angle θ of the vehicle body accompanying the lateral acceleration α is reduced by the stroke of the actuator ACTR.

FIG. 3 illustrates the outline of the system of the present invention by an equivalent model of one degree of freedom of the roll. A one rod type hydraulic cylinder 10 is provided as an actuator in the stabilizer bar. Both chambers of the cylinder 10 are pipe-connected to a hydraulic source and a reservoir via a direction switching valve 12 and a pressure control valve 11. The pressure control valve 11 adjusts the supply pressure to the cylinder 10 according to the exciting force of the solenoid SOLc. Regarding the directional control valve 12, by controlling the energization to the solenoids SOLa and SOLb, the cylinder side circuit is selectively selected between the free state in which the cylinder 10 can freely expand and contract, and the active state in which the cylinder 10 is operated in the forward and reverse directions. It is designed to switch to.

A controller 13 controls the direction switching valve 12 and the pressure control valve 11, and receives a detection signal of the vehicle speed V and a detection signal of the front wheel steering angle δf. Actual lateral acceleration α ₀
Is generated by the transfer function 1 / (1 + τ ₀ · s) of the first-order lag system based on the lateral acceleration gain Y _G0 according to the front wheel steering angle δf and the vehicle speed V, the controller 13 determines from the detected steering angle δf and the detected vehicle speed V. The pressure control valve 11 is calculated with the transfer function Kc / (1 + τc · s) of the first-order lag system that calculates the lateral acceleration predicted value α based on the lateral acceleration gain Y _G and also takes the control gain Kc into consideration.
A control signal (command voltage) is applied to the solenoid SOLa of. Here, s represents a Laplace operator.

At the same time, the directional control valve 1 is changed from the predicted value α.
2, the direction of operation of the directional control valve 1 is determined according to the determination.
It suffices to control the energization of the two solenoids SOLa and SOLb, and the cylinder 10 operates from the pressure control valve 11 to the direction switching valve 12
Receives the supply pressure to the one side chamber and operates to the expansion side or the contraction side while escaping the hydraulic pressure from the other side chamber, so that it is possible to reduce the roll angle of the vehicle body to the control target value by generating a reverse moment in the stabilizer bar. .

A specific application example of the present invention will be described below. In FIGS. 4 and 5, 20a is a vehicle front axle and 20b is also a rear axle, to which stabilizer bars 21a and 21b are respectively attached at the central portions thereof. A pair of left and right brackets 22a and 22b as bars
It is attached via. Stabilizer bars 21a, 2
Both ends of 1b are extended along the side rails 23 of the frame, and bushes 24a and 24b are provided at their tips. One side rail 23 has support rods 25a, 2
5b is attached at its upper end via rubbers 26a, 26b, and one-rod type hydraulic cylinders 10a, 10b are pin-connected on the opposite side rail 23 on the head side so as to be horizontally placed along the longitudinal direction of the vehicle.

The stabilizer bars 21a and 21b are provided with support rods 25a and 25b by bushes 24a and 24b on one end side.
The lower ends of the adjusting rods 27a and 27b are pin-coupled to the lower ends of the adjusting rods 27a and 27b by the bushes 24a and 24b on the other end side, and the bells that convert linear motion into rotational motion between the adjusting rods 27a and 27b and the hydraulic cylinders 10a and 10b. Cranks 28a, 2
8b is provided. The bell cranks 28a and 28b are attached to the side rails 23 at the middle portion of the L shape so as to be freely rotatable in the vertical direction via the shafts, and the bushes 29a and
It is connected to the piston rods of the hydraulic cylinders 10a and 10b via 29b and to the upper ends of the adjusting rods 27a and 27b on the other end side via bushes 30a and 30b.

The adjusting rods 27a and 27b are supported by the support rods 25a and 25b at the neutral position of the hydraulic cylinders 10a and 10b.
While supporting the ends of the stabilizer bars 21a and 21b at the same height as, the axles 20a and 20b bounce,
This is to absorb the displacement in the front-back direction that occurs when rebounding and the displacement when opening a store. Reference numerals 31a and 31b denote front and rear suspension springs.

The valve mechanism 43 of each cylinder 10a, 10b,
A controller 13 controls 44, and a steering angle sensor 3 for detecting the steering angle of the front wheels as a detecting means necessary for the control.
5, a vehicle speed sensor 36 that detects the traveling speed, load sensors 37 and 38 that detect the load on each wheel, and the cylinder 10.
In addition to the stroke sensors 39 and 40 that detect the stroke positions of a and 10b, the active sw that selectively commands the active mode of the stabilizer based on human operation.
41 and 42 are provided. In addition, each cylinder 10a, 1
As the 0b valve mechanisms 43 and 44, the same directional control valves 12a and 12b and pressure control valves 11a and 11b as in FIG. 3 are provided, respectively.

As shown in FIG. 6, the controller 13 has a lateral G calculating means 50 for calculating a predicted lateral acceleration value from the detection signals of the vehicle speed sensor 36 and the steering angle sensor 35 under the condition that the active sw 41, 42 are turned on, and a load sensor. Tire cornering power correction means 51 for correcting the predicted value of lateral acceleration from the detection signals of 27 and 38, and control pressure determination means 52 for respectively determining the control pressure from the predicted values of the front side and the rear side.
53 and valve mechanism driving means 54 and 55 for converting these determined pressures into control signals to the valve mechanisms 43 and 44 and outputting them. The stroke sensors 39 and 40 are turned on when the active sw is turned on when the vehicle goes straight,
A limiter function for keeping 10b within a predetermined stroke range is given to the valve mechanism driving means 54, 55.

The control contents of the controller 13 will be described with reference to the flowchart of FIG. 7, which is repeatedly executed at a predetermined control cycle. The meaning of the reference numerals used in the flow chart is shown in FIG. First, each load sensor 37, 3
The detection signal is read from 8 and necessary control parameters are read, and the vehicle specification value and the pressure control gain are calculated using these (1.01 to 1.04). The head-side and rod-side pressure control gains of the front wheel side cylinder 10a are expressed by equations (1) and (2), and the head-side and rod side pressure control gains of the rear wheel side cylinder 10b are expressed by equations (3) and (4). ) Each is required.

Then, the vehicle speed sensor 36 and the steering angle sensor 35
The detection signal is read from and the predicted value of the yaw angular acceleration is calculated (1.05, 1.06). This calculation process is expressed by the equation (5).
It is repeated in the order of (7) to (7), the yaw rate gain is obtained by the equation (5), and the yaw angular acceleration is calculated by the equation (6). Zero is given as an initial value for the yaw angular velocity, and when the calculation of the yaw angular acceleration is completed, this is integrated by equation (7) to obtain the yaw velocity to be used in the next calculation.

From this predicted value, the predicted value of the lateral acceleration acting on the front wheel side and the rear wheel side is calculated (1.07). First, the lateral acceleration gain is obtained by the equation (8), and this is used to obtain the equation (9)
The predicted value of the lateral acceleration on the front wheel side is calculated by, and the predicted value of the rear wheel side is calculated by Expression (10). This processing is also executed in the control cycle, and the predicted value that changes from moment to moment is obtained.

Next, the control pressure to the cylinders 10a and 10b is determined by calculation from the predicted value of the yaw angular acceleration (1.08). In the hydraulic cylinder 10a on the front wheel side, the differential value of the control pressure during the expansion side operation for supplying the hydraulic pressure to the head side chamber is expressed by the equation (11), and the differential value for the control pressure during the contraction side operation for supplying the hydraulic pressure to the rod side chamber is expressed by the equation ( 12), and the control pressure differential value at the time of expansion side operation for supplying the hydraulic pressure to the head side chamber in the hydraulic cylinder 10b on the rear wheel side is expressed by the formula (13), and the control at the time of contraction side operation for supplying the hydraulic pressure to the rod side chamber is also performed. The pressure differential value is calculated by the equation (14).

Cylinder 10 is obtained by integrating the differential values of equations (11) to (14) with equations (15) to (18), respectively.
The control pressure supplied to the a and 10b sides is determined. Expression (1
In the equations (1) to (14), zero is given as the initial value of the control pressure, and when the calculation of the control pressure differential value is completed, this is integrated by the equations (15) to (18) and used for the next calculation. Find the control pressure.

When the pressure control gains of the cylinders 10a and 10b are the same on the compression side and the extension side, the control pressure rises earlier than the head side on the rod side as shown in FIG. 9 due to the penetration volume of the piston rod.

Then, the predicted lateral acceleration values are compared with ± G ₀ (see FIG. 9) under the condition that the front wheel active sw 41 and the rear wheel active sw 42 are turned on.
According to the determination, the direction switching valve 12 is placed in a parallel communication position when the predicted value is + G ₀ or more, in a crossing communication position when the predicted value is −G ₀ or less, and in an open position when −G ₀ to + G _0. Solenoid SOLa to switch
And energize solenoid SOLb (1.10 to 10.
1.19). At the same time, the calculated value of the control pressure is converted into a command voltage, and when the predicted value is + G ₀ or more and -G ₀ or less, the command voltage is 0 V as the command voltage when -G ₀ to + G _0. Is applied to the solenoid SOLc of the pressure control valve 11 (1.20 to 1.25). FIG. 10 shows the relationship between the control pressure of the cylinder and the command voltage to the pressure control valve.

In the cylinders 10a and 10b, when the predicted lateral acceleration value is + G ₀ or more, the directional control valve 12 is provided in the rod side chamber.
The supply pressure is received from the pressure control valves 11a and 11b through a and 12b, and the piston rod contracts while releasing the hydraulic pressure from the head side chamber to the reservoir. When the predicted value is −G ₀ or less, the head side chamber receives the supply pressure, and the piston rod extends while releasing the hydraulic pressure in the rod side chamber. Predicted value is -G ₀
In the case of up to + G ₀ , the head side chamber and the rod side chamber are switched by the direction switching valves 12a, 12 as the pressure control valves 11a, 11b are stopped.
The piston rod is free to expand and contract because it is opened to the reservoir through b.

When the active sw 41, 42 is off, in addition to turning off the solenoid SOLa and solenoid SOLb of the direction switching valves 12a, 12b, the pressure control valve 11
The command voltage to a and 11b is maintained at 0 volt (1.26 ~
1.29).

With such a configuration, the active sw4
When turning on the 1,42, (predicted value in the range of -G ₀ ~ + G ₀ of the lateral acceleration) during straight running of the vehicle, the front side and the rear side of the hydraulic cylinder 10a, 10b is free and stabilizer bar 21a stretching, 21b of Since the twist is absorbed, the function of the stabilizer is canceled and a soft riding comfort of the vehicle is obtained.

When the vehicle turns due to a lane change or the like, the cylinders 10a and 10b respectively act on the extension side for a predicted value of -G ₀ or less and on the compression side for a predicted value of + G ₀ or more. Generates a moment in the stabilizer bar in the direction opposite to the roll. The thrust of the cylinders 10a, 10b acts with a first-order lag from the steering angle of the front wheels in the same manner as the actual lateral acceleration, so that the roll of the vehicle body is naturally suppressed to the target control value and the cylinders 10a, 10b are set in the neutral position. Also, it is possible to return properly.

FIG. 11 exemplifies the characteristics of the cylinder thrust force and the roll angle when the lane is changed. Since these characteristics also change based on the vehicle specification value and the pressure control gain,
For example, even if the load capacity of the vehicle changes, it is possible to secure appropriate active characteristics according to the actual tire cornering power. The solid line represents the free characteristic that the active sw is off and the cylinder freely expands and contracts, and the fine dotted line, the coarse dotted line, and the alternate long and short dash line represent the active characteristic with different target gains.

The lateral acceleration is calculated on the front side and the rear side, and the cylinders are individually controlled according to these calculations. It can be maintained well.

[0039]

In summary, according to the first aspect of the invention, the hydraulic cylinder that supports the end portion of the stabilizer bar, the pressure control valve that adjusts the supply pressure to the hydraulic cylinder, and the flow of the supply pressure to the expansion side of the cylinder. And a directional valve that switches to the compression side,
Means for detecting the traveling speed of the vehicle, means for detecting the steering angle of the front wheels, means for calculating a predicted value of lateral acceleration from these detection signals, means for calculating a control pressure according to the predicted value, A means for converting the calculated value into a control signal for the pressure control valve and outputting the control signal, a means for similarly determining the operating direction of the directional control valve based on the predicted value, and a control signal corresponding to the determination to the directional control valve. Since the output means is provided, it is possible to reduce the roll of the vehicle body in a natural and accurate manner, and it is also possible to appropriately return the cylinder to the neutral position.

According to the second aspect of the present invention, means for detecting the load of each wheel and means for correcting the predicted lateral acceleration value based on these detection signals are added to the first aspect of the invention. Even if the loading amount changes, the effect that the appropriate active characteristic can be secured according to the change can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram illustrating the principle of the present invention.

FIG. 2 is also an equivalent model diagram of one degree of freedom of roll.

FIG. 3 is a system schematic diagram of the same.

FIG. 4 is a schematic configuration diagram showing an embodiment of the present invention.

FIG. 5 is a mounting configuration diagram of a stabilizer bar of the same.

FIG. 6 is a block diagram of the same controller.

FIG. 7 is a flowchart for explaining the control contents of the controller.

FIG. 8 is a list similarly showing the meaning of the reference numerals.

FIG. 9 is a characteristic diagram similarly showing a relationship between a control pressure and a lateral acceleration predicted value.

FIG. 10 is a characteristic diagram similarly showing the relationship between control pressure and command voltage.

FIG. 11 is a characteristic diagram similarly showing a cylinder thrust force and a roll angle.

FIG. 12 is a diagram corresponding to the claims of the present invention.

FIG. 13 is a configuration diagram of a hydraulic system for explaining a conventional technique.

[Explanation of symbols]

 10a, 10b Hydraulic cylinder 11a, 11b Pressure control valve 12a, 12b Directional switching valve 13 Controller 20a Front axle 20b Rear axle 21a, 21b Stabilizer bar 35 Steering angle sensor 36 Vehicle speed sensor 37, 38 Load sensor 41, 42 Active sw

Claims (2)

[Claims] 1. A hydraulic cylinder that supports the end of a stabilizer bar, a pressure control valve that adjusts the supply pressure to the hydraulic cylinder, and a direction switching valve that switches the flow of the supply pressure between the expansion side and the compression side of the cylinder. Means for detecting the traveling speed of the vehicle,
A means for detecting the steering angle of the front wheels, a means for calculating a predicted value of lateral acceleration from these detection signals, a means for calculating a control pressure according to the predicted value, and a control signal for sending the calculated value to the pressure control valve. And a means for determining the operating direction of the directional control valve based on the predicted value, and a means for outputting a control signal corresponding to the determination to the directional control valve. And the stabilizer device of the vehicle. 2. The stabilizer apparatus according to claim 1, further comprising means for detecting a load on each wheel and means for correcting a predicted lateral acceleration value based on these detection signals.