JPS63162314A - Roll stiffness control device for vehicle - Google Patents

Abstract

PURPOSE:To restrain the sudden change of steering force, when the steering characteristics of a vehicle change with the control of the roll stiffness distribution of the vehicle, by changing the characteristics of fluid pressure to be used for the increase correction of steering force in response to this control. CONSTITUTION:A control means M3 outputs the command for controlling the roll stiffness distribution of a vehicle to a roll stiffness distribution control means M2 on the basis of the detected result of a running condition detecting means M1 of the vehicle. And an instructing means M5 instructs the liquid pressure characteristics determined on the basis of the detected result of the running condition detecting means M1 to a steering auxiliary means M4 acting on the steering of the vehicle. In this device, a changing means M6 which changes the fluid pressure characteristics determined by the instructing means M6 in response to the command of the control means M3 is provided. And when the steering characteristics of the vehicle change with the control of the roll stiffness distribution of the vehicle, the characteristics of fluid pressure to be used for the increase correction of steering force are changed in response to this control.

Description

[Detailed Description of the Invention] ``Field of Industrial Application'' The present invention provides a vehicle roll stiffness control device that is effective in suppressing changes in steering sensation caused by vehicle roll stiffness control. Regarding.

[Prior Art] When a vehicle turns, rolling occurs due to the action of centrifugal force. In this case, as the roll angle increases, the camber angle also changes, so the campus lath l~ increases and the maneuverability improves.
This leads to a decrease in stability. Therefore, in order to maintain the turning state, it is necessary to perform corrective steering frequently. In order to suppress such rolling and improve maneuverability and stability, it is conceivable to set the spring constant of the suspension high, for example. However, in this case, impactful vibrations, such as when driving on rough roads, are not absorbed, and ride comfort deteriorates.

Therefore, a vehicle is provided with a stabilizer that acts as a spring and generates a restoring force only when the suspension positions of the left and right wheels are different, in order to suppress rolling.

However, even if the vehicle is not rolling, for example, if one of the left and right wheels rides on a bump on the road surface, there will be a difference in the suspension position of the left and right wheels, so the stabilizer will generate torsional elastic force and act as a spring. It works. For this reason, the ride comfort deteriorates in the same way as when the spring constant of the suspension is set high. For example, the following techniques have been proposed as countermeasures against such inconveniences. That is, (1) A hydraulic piston having a predetermined stroke is interposed between the arm that holds the left and right wheels and the mounting part at one end of the stabilizer, and when driving normally straight, the hydraulic piston is in a movable state to operate the stabilizer. ``An automobile stabilizer mounting device'' (Japanese Unexamined Patent Application Publication No. 131024/1983) that fixes the hydraulic piston and operates the stabilizer only when turning by sensing centrifugal force.

(2) The stabilizer and the wheel side member are connected by a cylinder unit in which two cylinder chambers are formed by a piston and a cylinder body, and both cylinder chambers are connected to a pressure fluid source via a switching valve. A "stabilizer device" that adjusts the fluid pressure to expand and contract the cylinder unit to actively control the vehicle's attitude and prevent rolling when the vehicle turns
64514).

[Problems to be Solved by the Invention] Incidentally, the load transferred between the inner and outer wheels during a turn of a vehicle increases as the roll rigidity increases. That is, as shown in FIG. 12, when the roll rigidity is low, the load transferred from the inner turning wheel side to the outer turning wheel side is small as shown by arrow a. At this time, the load is transferred between the inner and outer wheels of the turning so that the amount of decrease in the wheel load on the inner wheel of the turning and the increase of the wheel load of the outer wheel of the turning become the same load f1 [Kg]. However,
When the roll rigidity increases, the load transferred from the inner turning wheel side to the outer turning wheel side increases as indicated by the arrow in the figure. At this time, the wheel load reduction amount on the inner wheel side of the turning and the wheel load increase amount on the outer wheel side of the turning are both equal to the load F1 [Kg]
The load is transferred between the inner and outer wheels when turning. here,
As shown in the figure, cornering power CP [Kg/
deg] and wheel load F[KFi] have a non-linear relationship, so cornering power CP when roll stiffness is high
1 [Kg/deg] is compared to the cornering power CP2 [Kg/deg] when the roll stiffness is low.
Generally, as shown in the following equation (1), △CP [Ky/deal
only tends to decrease.

CR2-CPl =ΔCP (1) On the other hand, the steering characteristics of the vehicle are determined according to the value of the following equation (2), which is determined based on the balance of forces during turning.

CPRXLR-CRFXLF...(2) However,
CPR... Cornering power of the rear wheels [R... Distance between the center of gravity of the vehicle and the rear wheel axle CPF... Cornering power of the front wheels 1F... Distance between the center of gravity of the vehicle and the axle of the front wheels The steering characteristics of the vehicle are expressed by the above formula. When the value of 2) is positive, understeer characteristics are obtained, when it is O, neutral steering characteristics are obtained, and when the value is negative, oversteer characteristics are obtained.

Therefore, when the stabilizer is operated by performing the control described in the above [Prior Art] section, a difference occurs in the roll stiffness between the front wheels and the rear wheels of the vehicle due to the operation of the stabilizer. This causes a change in the magnitude relationship between the front wheel cornering power CPF and the rear wheel cornering power CPR during cornering, and the variation in the value of equation (2) above changes the steering characteristics of the vehicle from the predetermined basics. This causes phenomena such as deviation from the characteristics. In other words, when only the stabilizer on the front wheel side is operated, the roll rigidity on the front wheel side increases, so the steering characteristics shift from the basic characteristic to the understeer characteristic side, while on the other hand, when only the stabilizer on the rear wheel side is operated, the roll rigidity on the rear wheel side increases. increases, so the steering characteristic shifts from the basic characteristic to the oversteer characteristic side. Also, if the front and rear stabilizers are activated at the same time,
It is also conceivable that the steering characteristics change depending on the stiffness of each of the stabilizers. In this way, when the roll stiffness distribution of the vehicle changes with the roll stiffness control of the vehicle, the steering characteristics of the vehicle shift to characteristics different from the predetermined basic characteristics. Therefore, when the roll stiffness of the vehicle is controlled, there is a problem in that the steering force necessary for steering the vehicle changes rapidly. In particular, since vehicle roll stiffness control is automatically performed depending on the vehicle's driving condition, sudden changes in steering force may place an excessive burden on the driver such as corrective steering, leading to a decrease in vehicle operability. There is also.

Further, if roll stiffness control is performed by limiting changes in roll stiffness distribution within a range that does not cause sudden changes in steering force as described above, a problem arises in that sudden changes in vehicle posture cannot be sufficiently suppressed. Therefore, there is a problem in that it is difficult to simultaneously correct the vehicle attitude by controlling the roll stiffness and ensure the maneuverability and stability of the vehicle by maintaining a predetermined steering force.

SUMMARY OF THE INVENTION An object of the present invention is to provide a roll stiffness control device for a vehicle that can suitably control the roll stiffness distribution of a vehicle without adversely affecting steering feel such as sudden changes in steering force.

Structure of the Invention [Means for Solving the Problems] The present invention, which has been made to solve the above-mentioned problems, as illustrated in FIG. The roll stiffness distribution adjusting means M2 adjusts the roll stiffness distribution of the vehicle according to a command from the vehicle, and the roll stiffness distribution adjusting means M2 adjusts the roll stiffness distribution of the vehicle based on the detection result of the driving state detecting means M1. a control means M3 that outputs an output to the adjustment means M2; and a steering assist that generates a steering output by increasing the steering force applied to the steering of the vehicle by using the fluid pressure regulated according to the fluid pressure characteristics instructed from the outside. A roll stiffness control device for a vehicle, comprising: means M4; and instruction means M5 for instructing the steering assist means M4 to determine the fluid pressure characteristic determined according to the detection result of the running state detection means M1, further comprising: The gist of the present invention is a roll stiffness control device for a vehicle, characterized in that it includes a changing means M6 that changes the fluid pressure characteristics determined by the indicating means M5 in accordance with a command from the controlling means M3.

The driving state detection means M1 detects the driving state of the vehicle. For example, it can be realized by a vehicle speed sensor that detects vehicle speed and a steering angle sensor that detects steering angle. Alternatively, for example, it may be realized by a combination of the above-mentioned two sensors with a vehicle width direction acceleration sensor that detects vehicle width direction acceleration, a yaw rate sensor that detects yaw angular velocity, or the like.

The roll stiffness distribution adjusting means M2 is for adjusting the roll stiffness distribution of the vehicle. For example, this can be realized by an actuator comprising a hydraulic cylinder that switches the distance between the unsprung member and the mounting portion of at least one of the front and rear stabilizers from a variable state to a fixed state. For example, if an air suspension is provided, the spring constant of the air suspension can be changed between the front wheel side and the rear wheel side by changing the cross-sectional area of the communication passage between the main air chamber and the auxiliary air chamber of the air suspension. It may also be configured by an actuator. Furthermore, for example, if a hydropneumatic suspension is provided, the spring constant of the hydropneumatic suspension can be adjusted between the front wheel side and the rear wheel side by adjusting the pressure inside the hydraulic pressure chamber or the pressure chamber of the hydropneumatic suspension. It may also be realized by a changeable actuator. For example, the suspension bushing may be constructed of an actuator that can change the rigidity of the suspension bushing between the front wheel side and the rear wheel side by supplying hydraulic pressure to a hydraulic pressure chamber inside the suspension bushing.

The control means M3 outputs a command for controlling the roll stiffness distribution according to the running state. For example, when the vehicle speed is at least a predetermined vehicle speed and the steering angle is at least a predetermined steering angle, the roll rigidity of at least one of the front wheels and the rear wheels can be increased.

The steering assist means M4 generates a steering output by increasing the steering force by using fluid pressure regulated according to fluid pressure characteristics instructed from the outside. Here, the fluid pressure may be, for example, hydraulic pressure, or may be, for example, compressed air pressure. The above-mentioned steering assist means M4 may include, for example, a control valve such as a solenoid valve interposed in a conduit leading from a hydraulic reaction force chamber provided in a rotary valve type hook and pinion gear housing to a reservoir tank, and receive instructions from the outside. By adjusting the opening degree of the control valve according to the control valve, it is possible to change the hydraulic reaction force against the steering force applied to the steering wheel, and furthermore, the hydraulic pressure is supplied to the power cylinder according to the steering operation, and the steering force can be increased and corrected. This can be realized by a so-called hydraulic reaction force type power steering device that generates a steering output. For example, a control valve such as a solenoid valve may be interposed in a bypass pipe connecting the left and right compartments of a power cylinder provided in a power steering gear box, and the opening degree of the control valve may be adjusted in accordance with instructions from the outside. It may also be configured with a so-called flow rate control type power steering device that changes the power assist force and generates the steering output by increasing the steering force.

The indicating means M5 is for indicating fluid pressure characteristics determined according to the driving state. For example, during stationary steering and low-speed driving, the hydraulic reaction force is determined to be a small force or the power assist force is determined to be a large force and an instruction is output.
When steering during medium/high speed driving, the configuration can be such that the hydraulic reaction force is determined to be a large force or the power assist force is determined to be a small force and an instruction is output.

The changing means M6 changes the fluid pressure characteristics determined by the indicating means M5 in accordance with a command from the controlling means M3.

For example, when the control means M3 outputs a command to increase the roll rigidity of the front wheels, the hydraulic reaction force determined by the instruction means M5 can be changed to a smaller force or the power assist force can be changed to a larger force. For example, when the control means M3 outputs a command to increase the roll rigidity of the rear wheels, the control means M5 is configured to change the hydraulic reaction force determined by the instruction means M5 to a larger force or the power assist force to a smaller force. It's okay.

The control means M3, the instruction means M5, and the change means M6 can be realized, for example, by independent discrete logic circuits. Alternatively, for example, it may be configured as a logical operation circuit together with a well-known CPU, ROM, RAM, and other peripheral circuit elements, and implement the above-mentioned means according to a predetermined processing procedure.

[Operation] As illustrated in FIG. 1, the vehicle roll stiffness control device of the present invention issues a command to control the roll stiffness distribution of the vehicle to the control means M3 based on the detection result of the running state detection means M1.
is outputted to the roll rigidity distribution adjusting means M2, and on the other hand, when the instruction means M5 instructs the steering assisting means M4 about the fluid pressure characteristics determined according to the detection result of the running state detection means M1, the changing means M6 It operates to change the fluid pressure characteristics determined by the means M5 in response to commands from the control means 3.

That is, when the steering characteristics of the vehicle change with the control of the roll stiffness distribution of the vehicle, the characteristics of the fluid pressure used to correct the increase in steering force are also changed in accordance with the control.

Therefore, the vehicle roll stiffness control device of the present invention works to suppress rapid fluctuations in steering force that occur with control of the vehicle roll stiffness distribution. The technical problems of the present invention are solved by each component of the present invention acting as described above.

[Example] Next, a preferred example of the present invention will be described in detail based on the drawings. FIG. 2 shows a system configuration of a roll stiffness control device that is an embodiment of the present invention.

As shown in FIG. 2, the roll stiffness control device 1 includes a stabilizer device 2, a power steering device 3, a vehicle speed sensor 4, a steering angle sensor 5, a vehicle width direction acceleration sensor 5a, and an electronic control device (hereinafter simply referred to as (referred to as ECU).

The stabilizer device 2 includes a connecting actuator 10 degrees interposed between the left attachment part of the front stabilizer bar 7 and the lower arm 9 of the left front wheel 8.
A connecting actuator 14 is provided between the left mounting portion of the bar 11 and the lower arm 13 of the left rear wheel 12. Note that there is a stabilizer link 17 between the right attachment part of the front stabilizer bar 7 and the lower arm 16 of the right front wheel 15, and the rear stabilizer bar 7 is connected by a stabilizer link 17.
The right mounting portion of the bar 11 and the lower arm 19 of the right rear wheel 18 are connected by stabilizer links 20, respectively.

On the other hand, the power steering device 3 includes a vane pump 21 that generates and supplies hydraulic pressure by receiving driving force from an engine (not shown), and a rotary valve containing hydraulic oil supplied from the vane pump 21, which operates a power cylinder 22. It consists of a steering gear box 23 that sends data to the left cylinder chamber or right cylinder chamber, a solenoid valve 24 that is attached to the steering gear box 23 and adjusts reaction pressure, which will be described later, and a reservoir tank 25 that stores hydraulic oil. The steering force is assisted by the hydraulic pressure sent to the power cylinder 22, and the steering output obtained by this assistance is transmitted by the tie rod, and the knuckle arms are actuated to drive the left and right front wheels 8, 15.
change the orientation.

Incidentally, since the configurations of the connecting actuators 10.14 of the stabilizer device 2 are similar, the connecting actuator 10 will be explained based on FIG. 3 as an example.

As shown in FIG. 3, the connected actuator 10 includes a cylinder 31 filled with hydraulic oil, a seal member 32 that oil-tightly seals the upper opening of the cylinder 31, and a cylinder 31 that is slidable in the cylinder 31. The fitted piston 33, the piston rod 34 fixed to the piston 33, the upper chamber 35 of the cylinder 31 divided by the piston 33, the royal chamber 3
6. Furthermore, the boat 35a of the upper chamber 35 and the lower chamber 36
A hydraulic circuit 37 connecting the boat 36a, a switching valve 38 and an accumulator 39 installed in the hydraulic circuit 37.
It consists of

The bottom of the cylinder 31 of the coupling actuator 10 is fixed to the lower arm 9 via a bush 40. On the other hand, the upper end of the piston rod 34 of the connecting actuator 10 is connected to the stabilizer bar 7 via a bush 41.
It is connected to the mounting part of.

The connected actuator 10 configured as described above operates as follows when the ECU 6 outputs a control signal for energizing or de-energizing the switching valve 38, which is a three-point/two-position solenoid valve. That is, in the case of de-energization, the switching valve 38 is in the position shown in FIG. Therefore, the upper chamber 35 and lower chamber 36 of the cylinder 31 of the coupling actuator 10 are in communication, and the change in the volume inside the cylinder 31 due to the sliding of the piston 33 is corrected by the accumulator 39.

Therefore, the piston 33 is slidable in the direction of the arrow and in the direction of the arrow B in the figure, and the distance between the mounting portion of the stabilizer bar 7 and the lower arm 9 becomes variable. As a result, the stabilizer bar 7 is in a state where it does not supply torsional elastic force to the lower arm 9, and does not function as a stabilizer.

On the other hand, when the switching valve 38 is energized by the ECU 6, the switching valve 38 is switched to the right position shown in FIG.

Therefore, the upper chamber 35 and lower chamber 36 of the cylinder 31 of the connected actuator 10 are in a disconnected state. Therefore, the piston 33 becomes unable to slide, and the distance between the mounting portion of the stabilizer bar 7 and the lower arm 9 is fixed at a predetermined distance.

Thereby, the stabilizer bar 7 is in a state where it can supply torsional elastic force to the lower arm 9, and acts as a stabilizer.

Next, the operation of the power steering device 3 is shown in FIGS. 4(1), (2>, (3), and FIG. 5(1)).

The explanation will be based on (2) and (3). Here, in Figure 4 (
2) is a cross-sectional view taken along the line C-C in FIG. 4 (1), FIG. 4 (3) is a cross-sectional view taken along the line D-D in FIG. 4 (1), and FIG.
), and Figure 5 (3) is the F-E cross-sectional view of Figure 5 (1).
It is an F sectional view. The detailed structure of the main part of the hydraulic circuit of the power steering device 3 is similar to that disclosed in, for example, "Power Steering Device for Vehicles" (Japanese Utility Model Publication No. 44365/1983).

As shown in FIG. 4 (1), the power steering device 3 supplies hydraulic oil from a reservoir tank 25 to a vane pump 21.
is sucked in and the pressure increases, and a constant flow of hydraulic oil is returned to the reservoir tank 25 via the solenoid valve 24 by the flow dividing valve 51 provided inside the steering gear box 23, and the remaining amount of hydraulic oil is transferred to the control valve section 52. supply to.

In the control valve section 52, the control valve shaft 53 rotates in conjunction with the rotation of the steering wheel 26, and the rotary valve 54 rotates in the same direction as the control valve shaft 53 due to torque transmitted via the torsion bar 55. However, rotary valve 5
Since the road resistance of the left and right front wheels 8.15 is transmitted to 4,
As shown in FIG. 4(2), the rotary valve 54 rotates behind the control valve shaft 53 by a relative rotational phase difference corresponding to the amount of twist of the torsion bar 55. Due to the relative rotational phase difference, the oil passage is switched in the control valve section 52 according to the rotational direction of the steering wheel 26.

Therefore, as shown in FIG. 4(1), when steering to the right, the control valve section 52 is connected to the power cylinder 2.
Hydraulic oil is supplied to the right cylinder chamber 22R of No. 2 (indicated by a solid line arrow), and a power assist force generated as the pressure inside the right cylinder chamber 22R increases, generates an assisted steering output in the direction of arrow G, The steering output is provided by tie rod 56L,
56R and knuckle arms 57L and 57R are operated to change the direction of the left and right front wheels 8 and 15 to the right. On the other hand, during left steering, hydraulic oil is supplied from the control valve section 52 to the left cylinder chamber 22L of the power cylinder 22 (
Indicated by dashed arrows. ), the power assist force generated as the pressure inside the left cylinder chamber 22L increases, generates an assisted steering output in the same direction as the arrow, and the steering output operates the tie rods 56L, 56R and the knuckle arms 57L, 57R. The orientation of the left and right front wheels 8, 15 is changed to the left.

Note that the power cylinder 22 portion is shown as a 90' exploded view.

Further, as shown in FIG. 4(1), a hydraulic reaction force chamber 58 is provided below the rotary valve 54 of the control valve section 52. The hydraulic reaction force chamber 58 is connected to the control valve shaft 53 as shown in FIG. 4(3).
four plungers 59 closely facing the lever portion 53a of the
a, 59b.

It is equipped with 59C and 59d. When the hydraulic pressure inside the hydraulic reaction chamber 58 (hereinafter referred to as reaction pressure) rises, the back surfaces of the seven lunges v59a, 59b, 59c, and 59d move in the direction shown by arrow J, and furthermore, the height of the reaction pressure increases. Since the plungers t59a, 59b, 59c receive a force corresponding to the
, 59d apply a pressing force to the lever portion 53a, and when the control valve shaft 53 rotates, it generates a reaction force that suppresses the rotation. In this way, the power steering device 3 shown in FIG. 4(1) controls the ECU to control the hydraulic pressure acting on the hydraulic reaction chamber 58 provided in the control valve section 52 of the steering gear box 23 according to the driving state.
6 is a so-called hydraulic reaction force type power steering device that changes the opening degree of a solenoid valve 24 to set an appropriate steering force according to various driving conditions.

Here, the opening area S of the communication hole 24a of the solenoid valve 24, that is, the opening degree of the solenoid valve 240 is
It increases in proportion to the average energizing current I to the solenoid valve 24 based on the control of No. 6. For example, during stationary steering and low-speed running, the average energizing current is large, so the opening degree of the solenoid valve 24 also becomes large, and a certain amount of hydraulic oil flows out from the flow divider valve 51 into the reservoir tank 25, causing the hydraulic reaction force chamber 5
Since the reaction pressure acting on the torsion bar 55 becomes lower, the steering force becomes only the torsional torque of the torsion bar 55, which becomes relatively light.

When driving in a straight line at medium or high speeds, the average energizing current I decreases as the vehicle speed increases, so the opening degree of the solenoid valve 24 becomes smaller, and the amount of hydraulic oil flowing out from the diversion valve 51 to the reservoir tank 25 decreases. As the amount of hydraulic oil supplied to the hydraulic reaction chamber 58 increases, the reaction pressure acting on the hydraulic pressure chamber 52 increases, so that the steering force is increased according to the torsional torque of the torsion bar 55 and the reaction pressure. It becomes the sum of the force and becomes relatively heavy.

During steering during medium/high speed running, the opening degree of the solenoid valve 24 is small, similar to the above-mentioned case when the vehicle is moving straight during medium/high speed running, so the reaction pressure is also high. In this case, as described above, the rotation of the control valve shaft 53 that is linked to the steering wheel 26 and the rotation of the rotary valve 54 that receives road resistance from the left and right front wheels 8 and 15 depend on the amount of twist of the torsion bar 55. A relative rotational phase difference is generated, and the oil pressure on the rotary valve 54 side increases due to the generation of throttling resistance according to the relative rotational phase difference. As the oil pressure on the rotary valve 54 side increases, hydraulic oil begins to be supplied from the pipe 60 toward the rotary valve 54 to the hydraulic reaction chamber 58 through the fixed orifice 61. Therefore, the hydraulic oil supplied to the hydraulic reaction chamber 5 through the fixed orifice 61 and the hydraulic oil supplied to the hydraulic reaction chamber 58 from the reservoir tank 25 by the vane pump 21 via the flow divider valve 51. , the reaction pressure acting on the hydraulic reaction force chamber 58 becomes even higher.

Therefore, the steering force becomes heavier in proportion to the steering angle. In this case, as mentioned above, the steering wheel 2
By generating the power assist force according to the steering angle of 6, a steering output that assists the steering force can be obtained.

By the way, if the average energizing current (■) to the solenoid valve 24 is increased during the above-mentioned steering during medium/high speed driving, the result will be as shown in Fig. 5 (1).
), the opening degree of the solenoid valve 24 increases. As a result, a portion of the hydraulic oil flowing into the hydraulic reaction chamber 58 through the fixed orifice 61 flows out into the reservoir tank 25 via the flow branch valve 51 and the flow hole 24a of the solenoid valve 24. Therefore, the amount of hydraulic fluid supplied to the hydraulic reaction chamber 58 through the fixed orifice 61 is reduced, and the reaction pressure acting on the hydraulic reaction chamber 58 is reduced to the solenoid valve 2.
4 is lower than when the opening degree is small. Due to such a decrease in reaction pressure, plunges t59a and 59b are caused, as shown in FIG. 5(3).

Forces acting on the back surfaces of 59c and 59d (indicated by arrows)
becomes smaller, and the reaction force acting on the control valve shaft 53 also becomes smaller. Therefore, the steering force becomes lighter than when the opening degree of the solenoid valve 24 is small. In addition, in this case as well, as shown in FIG. 5 (2),
Since the control valve section 52 operates in the same manner as described above, by generating a power assist force according to the steering angle, a steering output that assists the steering force can be obtained. In this way, by controlling the value of the average current I supplied to the solenoid valve 24 during steering during medium/high speed running, the weight of the steering force can be changed.

As shown in FIG. 6, the ECU 6 that controls the stabilizer device 2 and the power steering device 3 described above has
It is configured as a logic operation circuit centered around PLJ 6a, ROM 6b, and RAM 6C, and is connected to the input/output section 6e via a common bus 6d, and receives signals from each sensor and drives and controls the connected actuators 10, 14 and solenoid valve 24. do.

Next, the roll stiffness control process executed by the ECU 6 will be explained based on the flowchart shown in FIG. This roll stiffness control process is started when the ECU 6 is activated.

First, in step 100, a process is performed to read the vehicle speed V1 detected by the vehicle speed sensor 4 and the steering angle θ1 detected by the steering angle sensor 5. Subsequent steps 110, 120
Then, based on the vehicle speed V1 and steering angle θ1 read in step 100, it is determined whether or not it is necessary to increase the roll rigidity, and if an affirmative determination is made, the process proceeds to step 150.
On the other hand, if the determination is negative, the process proceeds to step 130. Here, to determine whether it is necessary to increase the roll rigidity,
This is performed based on whether the vehicle speed V1 and the steering angle θ1 are included in the control region L (shaded area) or the non-control region M of the map shown in FIG. In addition,
The boundary line between the control area RI and the non-control area M is calculated by the following formula (3
).

θ−fo (V) ...(
3> Therefore, in step 110, the boundary steering angle 0 corresponding to the vehicle speed v1 read in step 100 is determined.
1* is calculated as shown in the following equation (4) based on the above equation (3).

θ1*−fo(Vl)−(4) Next, proceed to step 120, and determine whether the steering angle θ1 read in the above step 100 is greater than or equal to the boundary steering angle θ1* calculated in the above step 110, If an affirmative determination is made, the process proceeds to step 150 as the area is included in the control area shown in the map of FIG.

The ECU 6 stores in advance a map as shown in FIG. 8 in the ROM 6b, and makes determinations according to the map.

In step 130, which is executed when it is determined that the running state of the vehicle is included in the non-control region M, the switching valve 38 of the front coupling actuator 10 is de-energized ( OFF) is output. This step 1
By the process 30, the front stabilizer bar 7 no longer functions as a stabilizer, and the roll rigidity on the front side decreases. In addition, the rear connecting actuator 1
4 is also in the de-energized (OFF> state), so the rear stabilizer bar 11 also does not act as a stabilizer.In the subsequent step 140, the front stabilizer bar 7 ceases to act as a stabilizer as a result of the processing in step 130, so the front stabilizer bar 7 stops acting as a stabilizer. Processing is performed to select the average current supply characteristics to the solenoid valve 24 of the power steering device 3 in the control region M. Here, the average conduction current ■ and the vehicle speed V are defined as shown in the map shown in FIG. The average conduction current characteristic in the non-control region M decreases as the vehicle speed V increases, as shown by the broken line in the figure.
Moreover, it is set relatively low during medium and high speed driving. ECLI6 pre-routes a map like the one shown in Figure 9.
It is stored in M6b, and the average lightning current characteristic of the non-control area M is selected from the map. Next, the process proceeds to step 170, in which the solenoid valve 24 of the power steering device 3 is energized according to the average energization current characteristic of the non-control area M selected in step 140, and then the process returns to step 100. Note that the average energizing current (■) and the opening area S of the communication hole 24a of the solenoid valve 24 are
There is a proportional relationship as shown in the graph of Figure 0. Therefore, when steps 140 and 170 are executed, the reaction pressure acting on the hydraulic reaction chamber 58 of the power steering device 3 increases due to the decrease in the average energizing current (2) as described above, and as the vehicle speed increases. The steering force becomes heavier due to the increase in reaction force.

On the other hand, in step 150, which is executed when it is determined in step 120 that the running state of the vehicle is within the above-described control region, the front connecting actuator 10 is
A process is performed to output a control signal to energize (ON>) the switching valve 38 of the switch valve 38. Through the process of this step 150, the front stabilizer bar 7 acts as a stabilizer, increasing the roll rigidity of the front side. The rear stabilizer bar 11 is in a state in which it does not function as a stabilizer.In the subsequent step 160, the roll stiffness distribution of the vehicle changes in accordance with the processing in step 150, so that the solenoid valve 24 of the power steering device 3 in the control area is The average current characteristics of
The process of selecting from the map shown in FIG. 9 described above is performed. The average current characteristics in the control region decrease as the vehicle speed V increases, as shown by the solid line in Fig. 9, but in the middle and
During high-speed running, the average energizing current characteristic (indicated by the broken line in the figure) of the above-mentioned non-control region M is set higher than the above-mentioned average current characteristic. Next, the process proceeds to step 170 described above, and the solenoid valve 24 of the power steering device 3 is
After performing the process of energizing, the process returns to step 100 described above. When the above steps 160 and 170 are executed, as mentioned above, the reaction pressure acting on the hydraulic reaction chamber 58 of the power steering device 3 decreases by -30= due to the increase in the average energizing current ■, so that the above-mentioned The steering force becomes lighter compared to when the solenoid valve 24 is energized according to the average energization current characteristics of the control region M (steps 140 and 170). Thereafter, in this roll stiffness control process, steps 100 to 170 described above are repeatedly executed.

Note that in this embodiment, the vehicle speed sensor 4 and the steering angle sensor 5
corresponds to the running state detection means M1, and the stabilizer device 2 corresponds to the roll rigidity distribution adjustment means M2. Also, EC
Processes executed by U6 and the ECU 6 (step 110
, 120, 130° 150) function as the control means M3. Further, the power steering device 3 corresponds to the steering assist means M4, and the ECU 6 and the processing executed by the ECU 6 (step 140) serve as the instruction means M5.
(Step 160) each functions as the changing means M6.

As explained above, in this embodiment, when the vehicle speed v1 and the steering angle θ1 are within the control range, the front stabilizer bar 7 is actuated as a stabilizer by energizing the switching valve 38 of the front coupling actuator 10. Accordingly, the average energizing current characteristic to the solenoid valve 24 of the power steering device 3 is changed to the average energizing current characteristic in the control region, which is set to a higher current value during medium and high speed driving than the average energizing current characteristic in the non-control region M. The solenoid valve 24 is controlled according to the average current characteristics of the control region.
It is configured to energize. Therefore, even if the steering characteristics of the vehicle shift from the basic characteristics to the understeer characteristics due to an improvement in the roll rigidity on the front side, the reaction pressure acting on the hydraulic reaction chamber 58 of the power steering device 3 is reduced. Since this reduces the reaction force acting on the steering wheel 26, a sudden increase in steering force can be prevented. In other words, as shown by the solid line in Fig. 11, if the reaction pressure is corrected to decrease when the driving condition is within the control range, the steering force becomes relatively light even when driving at medium and high speeds, and moreover, the steering force decreases as the vehicle speed increases. Does not increase with rise. However, if the reaction force pressure is not corrected when the driving condition is within the control range as in the past, the steering force will increase rapidly during medium and high speed driving, as shown by the broken line in the same figure. It further increased as the vehicle speed increased. In this way, when control is performed to increase the front roll stiffness, an increase in steering force is suppressed by correcting the reduction in reaction force pressure, so that a good and stable steering feeling can be maintained at all times.

In addition, along with the above effects, it is possible to eliminate the adverse effects of rolling suppression control of the vehicle, such as an increase in steering force caused by sudden changes in steering characteristics. - It is possible to suitably maintain stability.

Furthermore, since there is no sudden change in steering feel, the burden on the driver is reduced and the operability of the vehicle is improved.

Moreover, each of the above-mentioned effects can be achieved with a simple device configuration that utilizes the stabilizer device 2 and power steering device 3 that are pre-installed in the vehicle.

Therefore, there is no need to newly equip a dedicated device, etc., so problems such as an increase in the weight of the vehicle and securing of mounting space do not occur, and fuel consumption efficiency does not decrease.

In the present embodiment, a case has been described in which only the front stabilizer bar 7 acts as a stabilizer when the vehicle running state falls within the control range. However, for example, the present invention can also be applied to a vehicle in which only the rear stabilizer bar 11 acts as a stabilizer to perform rolling suppression control. In this case, as the rear roll stiffness increases, the steering characteristics shift from the basic characteristics to the oversteer characteristics side, so the average current characteristics in the control region are changed to roughness when driving at medium and high speeds, contrary to this example. If the steering force is configured to be set to a small value and corrected to increase the reaction force pressure to suppress a sudden decrease in the steering force, the steering feeling can be maintained constant.

Further, in this embodiment, the reaction force pressure of the hydraulic reaction force type power steering device 3 is corrected to decrease to prevent an increase in the steering force. However, for example, a flow-controlled power steering device can also be used. In this case, the power assist force is controlled by adjusting the opening degree of a flow control valve provided in a bypass pipe connecting the left and right cylinder chambers of the power cylinder. In other words, when the front roll stiffness is increased, the steering characteristics shift from the basic characteristics to the understeer characteristics side, so the opening degree of the flow control valve is reduced to increase the power assist force, while the rear roll stiffness is increased. When the rigidity is increased, the steering characteristic shifts from the basic characteristic to the oversteer characteristic side, so if the opening degree of the flow control valve is increased and the power assist force is reduced and corrected, a sudden change in the steering feeling can be prevented.

Further, in this embodiment, the front stabilizer bar 7 is operated as a stabilizer to perform control to increase the front roll rigidity. However, for example, even in a vehicle equipped with an air suspension or a hydropneumatic suspension, etc., which performs rolling suppression control by changing the roll stiffness distribution of the vehicle, the configuration is configured to correct the reaction force pressure or power assist force of the power steering device. Then, the same effect as this embodiment is achieved.

Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments in any way, and it goes without saying that it can be implemented in various forms without departing from the gist of the present invention. .

Advantages of the Invention As detailed above, the vehicle roll stiffness control device of the present invention adjusts the fluid pressure used to correct the increase in steering force when the steering characteristics of the vehicle change due to the control of the roll stiffness distribution of the vehicle. It is configured to change the characteristics of according to the above control. As a result, sudden changes in steering force that occur due to control of the roll stiffness distribution of the vehicle are suppressed, resulting in the excellent effect that the steering feeling of the vehicle can always be maintained in an optimal and stable state.

In addition, sudden changes in steering force can be avoided even if the roll stiffness distribution is controlled at any time as needed depending on the vehicle's driving condition, so roll stiffness control suppresses changes in vehicle posture and maintains a predetermined steering feel, improving maneuverability. - Achieves both improved stability and improved stability.

In other words, since the steering feel is always maintained in a predetermined state, an excessive burden is not placed on the driver, and the vehicle can be operated easily.

In addition, in order to achieve each of the above effects, there is no need to newly install dedicated equipment in the vehicle, so the device configuration can be simplified, and the disadvantages such as expanding the mounting space in the vehicle and increasing the vehicle weight can be avoided. Since this does not occur, a predetermined fuel consumption efficiency can be ensured.

[Brief explanation of the drawing]

FIG. 1 is a basic configuration diagram illustrating the content of the present invention, FIG. 2 is a system configuration diagram of an embodiment of the present invention, FIG. 3 is an explanatory diagram showing the configuration of the connected actuator, and FIG.
), (2>, (3), Fig. 5 (1), (2>, (3)) are explanatory diagrams showing the operation of the power steering device, and Fig. 6 similarly shows the configuration of the electronic control device. A block diagram, FIG. 7 is a flowchart showing the control,
Figures 8 and 9 are graphs showing the same map.
Figure 0 is a graph showing the relationship between average current and solenoid valve flow hole opening area, Figure 11 is a graph showing the relationship between vehicle speed and steering force, and Figure 12 is a graph showing the relationship between wheel load and cornering power. It is a graph showing a relationship. Ml... Running state detection means M2... Roll rigidity distribution adjustment means M3... Control means M4... Steering assisting means M5... Indicating means M6... Changing means 1... Roll stiffness control device 2... Stabilizer device 3... Power steering device 4... Vehicle speed sensor 5... Steering angle sensor 6... Electronic control unit (ECU) 6a... CPU

Claims (1)

[Scope of Claims] 1. Running state detection means for detecting the running state of the vehicle; Roll stiffness distribution adjusting means for adjusting the roll stiffness distribution of the vehicle according to an external command; and a detection result of the running state detection means. A control means outputs a command for controlling the roll stiffness distribution of the vehicle to the roll stiffness distribution adjusting means based on the above, and the steering of the vehicle is controlled by using fluid pressure regulated according to fluid pressure characteristics instructed from the outside. a steering auxiliary means for generating a steering output by increasing the steering force applied to the vehicle; and an instruction means for instructing the steering auxiliary means to determine a fluid pressure characteristic determined according to a detection result of the driving state detecting means. A roll stiffness control device for a vehicle, further comprising a changing means for changing the fluid pressure characteristic determined by the instruction means in accordance with a command from the control means. .