JP2535602B2 - Suspension control device for vehicle - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a vehicle suspension control device in which a vehicle stabilizer is provided with a retractable cylinder device.

[Conventional technology]

Conventionally, there are the followings for controlling the attitude of the vehicle.

(1) The stabilizer and the wheel-side member are connected by a cylinder unit having two cylinder chambers 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" for controlling rolling of the vehicle by controlling the posture of the vehicle by positively utilizing the action of the stabilizer by adjusting the fluid pressure to expand and contract the cylinder unit (JP-A-61-64514). Issue).

(2) A “vehicle attitude control device” that calculates a control amount corresponding to a roll amount of a vehicle based on a running speed and a steering angle of the vehicle and changes a torsional elasticity characteristic of a stabilizer according to the control amount (Japanese Patent Application Laid-Open No. H10-163873). JP-A-61-146612).

[Problems to be Solved by the Invention]

When the active control of the stabilizer is realized for the purpose of adjusting the roll rigidity of the vehicle by supplying the pressure fluid from the fluid pressure source to the cylinder unit according to the running state of the vehicle as in the above-mentioned conventional technique, the capacity of the fluid pressure source The responsiveness of control is limited by characteristics such as the supply speed of the pressure fluid and the operating speed of the cylinder unit. However, in the case of turning by gentle steering, even if the turning lateral acceleration is large, the expansion / contraction speed of the cylinder unit is low, so that it is possible to respond to the required expansion / contraction amount even if the response is somewhat poor. It is possible to maintain the vehicle attitude. However, when performing sudden steering turning, such as when suddenly avoiding danger, both the transient roll speed and the absolute amount of the roll angle increase, and the cylinder is used to stabilize the vehicle attitude. Both the expansion speed and the expansion amount required for the unit are increased. For this reason, as described above, if the response is poor, the control delay becomes noticeable, and once the vehicle body starts rolling, the phenomenon of pushing back the vehicle body in the direction of suppressing the roll by the expansion and contraction control of the cylinder unit occurs. Is very different from the behavior of a normal driver (and an occupant) as the behavior of the vehicle while turning, and thus becomes extremely uncomfortable. Therefore, as a countermeasure against the problem, when the amount of expansion / contraction of the cylinder unit increases as the target roll rigidity increases, such as at the start of sudden steering, the damping force of the suspension is changed to a high side to activate the stabilizer. An improved technique for compensating for the control delay was also considered. However, if the control for changing the damping force to the higher side and the active control of the stabilizer for improving the roll rigidity are executed at the same time, it is suitable for the initial stage of the transient state such as during a sharp turn in which the control delay of the active control of the stabilizer occurs. However, the control delay of the active control of the stabilizer is eliminated and the expansion / contraction amount of the cylinder unit can follow the target stroke amount. At the end of the transient state, the damping force is changed to the higher side, so the stabilizer The problem that the control amount becomes an excessive value and the vehicle rolls back in the opposite direction was also found, and the above improvement technique was not yet sufficient.

That is, as shown in the timing chart of FIG. 10, when the steering angle θ sharply increases at the beginning of a transient state such as during sudden steering, the control delay of the active control of the stabilizer is compensated by changing the damping force to the higher side. Therefore, since the vehicle moves to the turning traveling state while exhibiting a predetermined roll rigidity, the roll angle of the vehicle does not increase so much and large rolling does not occur. However, at the end of the transient state when the control delay is eliminated and the stabilizer starts to operate effectively, the damping force is changed to the high side, so the roll rigidity improvement by the active control of the stabilizer becomes over-controlled, and The roll angle (indicated by diagonal lines in the figure) begins to increase, and the vehicle body rolls toward the turning inner wheel side (reverse direction).

The rolling in the reverse direction due to the over-control of the stabilizer is noticeable as a reversal occurring at the end of the transient state, particularly at the time of a sharp turn, and may give an occupant an uncomfortable feeling.

Further, in the combined control of the control for changing the damping force to the higher side as described above and the active control of the stabilizer,
The damping force changing control has a relatively high responsiveness and therefore exhibits a quick action. On the other hand, the stabilizer active control has a relatively low responsiveness and thus requires a predetermined time to operate effectively. However, no consideration is given to the response time difference between the two controls as described above, and the active control of the stabilizer for the purpose of adjusting the roll rigidity does not cause reverse rolling due to over-control at the end of the transient state such as during sudden steering. There is a room for improvement, because a new problem that it may cause the above phenomenon and that the rolling suppression effect cannot be sufficiently exerted is considered.

The present invention, when performing active control of the stabilizer for adjusting roll rigidity, when the control amount changes abruptly, for example, even at the end of a transient state such as during a sharp turn, the reverse control caused by the overcontrol of the stabilizer is performed. An object of the present invention is to provide a suspension control device capable of suitably suppressing the occurrence of rolling in the direction.

[Means for solving the problem]

Therefore, as shown in FIG. 1, the present invention provides an extendable cylinder device between a vehicle stabilizer and a vehicle,
A suspension control device for a vehicle, comprising a stabilizer control for controlling a roll generated in a vehicle by controlling expansion and contraction of the cylinder device based on a target control value according to a vehicle turning state, and further according to a command from the outside. A damping force adjusting means capable of adjusting the damping force of the suspension of the vehicle in at least two stages; a running state signal generating means for generating a running state signal according to a running state of the vehicle; and a sharp turning state based on the running state signal. And a sudden turning determination means for determining the start of the suspension, and when it is determined by the rapid turning determination means that the rapid turning state has started, the damping force of the suspension is reduced to suppress the roll that occurs initially in the rapid turning state. Based on the changing means for outputting a command to change to a higher side to the damping force adjusting means, and the traveling state signal, the vehicle is issued. Target control value calculating means for calculating a target value for adjusting the expansion / contraction amount of the cylinder device so as to suppress rolls, expansion / contraction amount detecting means for obtaining the actual expansion / contraction amount of the cylinder device, and the target control value. The actual amount of expansion and contraction of the cylinder is compared, and the control end condition in which the difference between the target control value and the actual amount of expansion and contraction becomes smaller than a predetermined value is determined for the first time after the start of a sharp turn, and based on this control end condition. And a control end determination means for outputting a command for returning the damping force of the vehicle from the high side to the low side to the damping force adjusting means.

[Action]

According to the present invention, when it is determined that the vehicle is in a sudden turning state, the damping force of the vehicle is changed to a higher side, and the cylinder provided in the stabilizer is based on the target control value for suppressing the roll generated in the vehicle. Stretch control of the device. By combining these two controls, the active control delay of the stabilizer can be suitably compensated at the initial stage of a sharp turn.

Further, when the control end condition that the difference between the actual stroke and the target stroke becomes smaller than a predetermined value is determined for the first time after starting the active control of the stabilizer, the damping force of the vehicle is returned to the low side. As a result, at the time of the control end condition where the control delay of the stabilizer is eliminated and the roll is appropriately suppressed, that is, at the end of the transient state, the damping force of the vehicle is returning to the low side, so the roll rigidity is over-controlled. The occurrence of rolling in the reverse direction of the vehicle is suppressed.

〔The invention's effect〕

As described above, according to the present invention, the rolling-back that occurs at the end of the transient state, such as during a sharp turn, is eliminated, the occupant does not feel uncomfortable, and the vehicle attitude does not suddenly change, so that the steerability and stability are improved.

Further, as described above, when executing the combined control of the active control of the stabilizer and the damping force change control, the damping force change control has relatively high responsiveness, while the active control of the stabilizer has relatively low responsiveness and is effective. Careful consideration should be given to the response time difference between the two controls, which requires a certain time delay before they act, and the follow-up of the active control of the stabilizer, which has a low response, does not cause over-control at the end of the transient state, such as during a sudden turn, without a sudden control. It is possible to realize highly reliable comprehensive control of the suspension that can exert a sufficient rolling suppression effect at the initial and final stages of the transient state during turning.

〔Example〕

 Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 shows an overall configuration of a vehicle attitude control device to which the present invention is applied. Here, hydraulic cylinder control is applied to a front wheel side stabilizer of a vehicle, and damping force control is applied to a four-wheel shock absorber. The applied example is shown.

As shown in the figure, the vehicle attitude control device 1 includes a front wheel side stabilizer device 2, a hydraulic device 3, a shock absorber damping force varying device 5, and an electronic control device 4 for controlling these.

In the front wheel stabilizer device 2, the left front wheel 6 is supported by the vehicle body 9 by the left front wheel shock absorber 7 and the left front wheel suspension arm 8. Also, the right front wheel 10
Is supported on the vehicle body 9 by a right front wheel shock absorber 11 and a right front wheel suspension arm 12. further,
The torsion portion of the front wheel stabilizer bar 13 is rotatably supported on the vehicle body 9 by bearings 14 and 15 fixed to the vehicle body 9 with bolts or the like. One end 13a of the front wheel side stabilizer bar 13 has a cylinder unit 1 whose connection distance can be adjusted.
It is coupled via 6 to the unsprung part of the right front wheel shock absorber 11. The connection distance between the one end portion 13a of the front wheel side stabilizer bar 13 and the unsprung portion of the right front wheel shock absorber 11 is supplied with pressure oil from the hydraulic circuit 3 in accordance with a control signal of the electronic control unit 4, and is connected to the front wheel side. It can be adjusted by expanding and contracting the cylinder unit 16. The other end 13b of the wheel side stabilizer bar 13 is attached to the unsprung portion of the left front wheel shock absorber 7 via a link rod 17. Further, in order to steer the vehicle, a steering mechanism 19 that changes the directions of the left and right front wheels 6 and 10 in accordance with the operation of the steering wheel 18 is also provided.

The shock absorber damping force varying device 5 includes a damping force control actuator 51 mounted on the upper part of the left front wheel shock absorber 7, a damping force control actuator 52 mounted on the upper part of the right front wheel shock absorber 11, and left and right rear wheel shocks (not shown). It consists of damping force control actuators, each mounted on top of the absorber. These damping force control actuators 51, 52 are connected to the electronic control unit 4
The control signal adjusts the damping force in two steps, a soft mode and a hard mode.

The vehicle attitude control device 1 includes, as detectors, a vehicle speed sensor 41 for detecting the traveling speed of the vehicle, a steering angle sensor 42 for detecting a steering angle, and a cylinder unit 16 extending relative to its neutral position (midpoint of piston stroke). The stroke expansion / contraction switch 43 is provided to detect whether it is on the side or on the contracted side.
The signals from these detectors are input to the electronic control unit 4, and the electronic control unit 4 controls and drives the hydraulic unit 3 to control and drive the front wheel stabilizer unit 2 and the shock absorber damping force varying unit 5. This adjusts the damping force of the four shock absorbers.

The cylinder unit 16 has a rod, as shown in FIG.
27 is attached to the lower front spring of the right front wheel shock absorber 11, which is also shown on the right front wheel coil spring 11a.
Is coupled to one end portion 13a of the front wheel side stabilizer bar 13. Therefore, the front wheel side stabilizer device 2 also changes the torsion amount of the front wheel side stabilizer bar 13 by the movement of the piston 22 of the cylinder unit 16 over a predetermined stroke amount, and changes the apparent torsional rigidity by increasing the torsion reaction force. Is configured.

As shown in FIG. 4, the cylinder unit 16 is operated by pressure oil supplied from the hydraulic device 3 in response to a control signal from the electronic control unit 4.

In the hydraulic device 3, the hydraulic pump 31 driven by the engine 30 sucks hydraulic oil from the reservoir tank 34, and
Pressure oil is supplied to the cylinder unit 16 via a, the control valve (four-port three-position solenoid valve) 32, and the conduits 33c and 33d. Control valve 32
Is a neutral position in response to a control signal from the electronic control unit 4.
It can be switched to three positions of 32a, extended position 32b, contracted position 32c and any intermediate position thereof.

Here, the configuration of the control valve 32 will be briefly described. The control valve 32 can be realized by, for example, a spool valve structure having two linear solenoids. When only one of the two linear solenoids is energized, the control valve 32 moves from the neutral position 32a to the extension position 32b side, and when the other is energized, the control valve 32 is energized. It moves to the contracted position 32c side, and the movement amount of the spool can be changed by the energizing current. With this configuration, the expansion and contraction of the cylinder unit 16 can be selected by selecting the solenoid to be energized, and the opening area of the port connected to the conduit on the outflow side of the cylinder unit 16 can be changed according to the magnitude of the energized current, thereby changing the cylinder unit The amount of oil spilled from 16 can be adjusted. That is, the control valve 32 realizes the function of the three-position directional control valve and the flow rate control function of the meter-out hydraulic circuit with one valve.

Next, the shock absorber damping force varying device 5 will be described. In the shock absorber damping force varying device 5,
The four wheels are composed of a damping force variable type shock absorber and a damping force control actuator having the same structure.
Here, as an example, the damping force variable shock absorber 7 for the left front wheel and the damping force control actuator 51 will be described.

The variable damping force type shock absorber 7 is shown in FIG.
As shown in FIG. 3, the outer cylinder 70 has a hollow piston rod 71 and a piston 72 slidably fitted in the outer cylinder 70.
A control rod 73 is loosely fitted inside the piston rod 71, and the control rod 73 is supported by a guide 73a fixed to the piston rod 71. The control rod 73 is a damping force control actuator described later.
The rotary valve 74 which is rotated by 51 and fixed to the control rod 73 is rotated to open and close the orifice 75.
Plate valves 76 and 77 are pistons with nuts 78 and 79, respectively.
It is fixed at 72.

When the piston rod 71 and the control rod 73 are in the positional relationship as shown in FIG. 5 (B), that is, the control rod 73 with respect to the front direction indicated by the arrow F.
Is in a position forming an angle of 90 °, the above-mentioned orifice 75 is in a communication state. Further, on the contracted side, as shown in FIG. 5 (A), the plate valve 76 is opened and the sub flow passage is opened.
80a communicates. On the other hand, on the extended side, as shown in FIG. 5 (C), the plate valve 77 is opened and the sub-flow path 80b is in communication. Therefore, the hydraulic oil flows through the passages of both the orifice 75 and the auxiliary flow passage 80a on the contraction side as shown by the arrow u in FIG. 5 (A), and on the expansion side by the arrow v in FIG. 5 (C). As shown, flow through both the orifice 75 and the sub-flow path 80b,
Since the throttling resistance of the hydraulic oil is small, the damping force of the variable damping force type shock absorber 70 is set to the low side (Soft).

On the other hand, when the piston rod 71 and the control rod 73 are in the positional relationship shown in FIG. 6 (B), that is, the front direction indicated by the arrow F and the control rod 73.
If and are in parallel positions, the orifice 75
Is cut off. Therefore, on the contraction side, the hydraulic oil flows only through the sub flow path 80a as shown by an arrow U in FIG. 6 (A), while on the extension side, as shown by an arrow V in FIG. 6 (C). In addition, since only the sub-flow path 80b flows and the throttling resistance of the hydraulic oil is large, the damping force of the damping force variable shock absorber 70 is set to the high side (Hard).

The damping force control actuator 51 will be described with reference to FIG. The damping force control actuator 51 is
A DC motor 90, a pinion gear 91 fitted to the shaft of the DC motor 90, and a sector gear 92 meshing with the pinion gear 91 are provided. The control rod 73 described above is fixed to the center of the sector gear 92. DC motor 90 will be described later
When the ECU 4 controls forward and reverse, the control rod 73
Changes the damping force of the shock absorber 22 by opening and closing the above-mentioned orifice 75 by reversing forward and backward. The sector gear 92
The rotation of the control rod 73 is limited to 90 ° or less by a lever 94 provided on the central shaft 93 and stoppers 95, 96 arranged at 90 ° to each other.

The electronic control unit 4 is composed of a microcomputer and the like, and has an input unit 4d for inputting signals from various sensors, a central processing unit (CPU) 4a for performing arithmetic processing based on these input signals, an arithmetic program, and a fixed unit. A read-only storage unit (ROM) 4b that stores data and the like, a storage unit (RAM) 4c that temporarily stores the operation result and control state, and an output unit that outputs a control signal to the control valve 32 based on the operation result. 4e, and a common bus 4f that connects these parts to each other.

Signals of a vehicle speed sensor 41 for detecting a vehicle speed, a steering angle sensor 42 for detecting a rotation angle (steering angle) of a steering wheel, and an expansion / contraction switch 43 for detecting an expansion / contraction state of the cylinder unit 16 are provided to an input section of the electronic control unit 4. Is entered.

The expansion / contraction switch 43 can be realized by the following configuration, for example. The piston rod 27 of the cylinder unit 16 has a structure in which a magnetic material and a non-magnetic material such as iron and stainless steel are connected together in the middle, and a coil around which a conductive wire is wound so that the piston rod 27 becomes the inner core is formed on the upper portion of the cylinder 21. Install. When the inductance of the coil is measured with such a structure, the values obtained when the inner core is made of a magnetic material such as iron and the case where the inner core is made of a non-magnetic material such as stainless steel are greatly different. Therefore, connecting a resistor in series, measuring the time constant of the output response to the pulse voltage input, measuring the resonance frequency, measuring the phase difference of the current to the AC voltage input, etc. A threshold circuit for determining the magnetic material side) and the smaller side (non-magnetic material side) may be provided in the input section 4d of the electronic control unit 4. Since the expansion / contraction switch having such a configuration can realize the sensor unit with a single coil, it can be used even in an unsprung part of a vehicle where environmental conditions such as temperature and vibration are severe.

Next, a basic operation and control method will be described based on the above configuration.

First, straight traveling will be described. In straight traveling, the control valve 32 shown in FIG. 4 is set to the neutral position 32a.
At this time, the pressure oil discharged from the hydraulic pump 31 is
Return to the reservoir 34 via a, the control valve 32, and the conduit 33b. on the other hand,
Since the conduits 33c, 33d are shut off by the control valve 32, the upper and lower chambers 25, 26 of the cylinder unit 16 are kept in an oil tight state, and the piston 22 is fixed in the cylinder 21. That is, the cylinder unit 16 is fixed so that it cannot expand and contract, and the link rod 17
In the same manner as described above, the stabilizer 13 acts as a kind of rigid body, and the stabilizer 13 exhibits its inherent torsional rigidity, so that traveling stability of the vehicle can be secured. Further, each damping force type shock absorber is controlled to a state as shown in FIG. 5 and set to a low damping force (Soft) state. As a result, shocking vibrations from the road surface such as when riding over bumps are absorbed, and deterioration of riding comfort can be prevented.

Next, turning will be described. At the time of turning, according to the predetermined relationship according to the vehicle speed and the size of the steering angle,
Determine the target expansion / contraction amount of the cylinder unit 16. Depending on the value, to extend or contract the cylinder unit,
The hydraulic device 3 is driven. That is, in the extension mode, the linear solenoid that drives the control valve 32 to the extension position 32b side is energized. At this time, in the control valve 32, the port connected to the conduit 33d connected to the lower chamber 26 of the cylinder unit 16 is immediately fully opened, and the pressure oil from the pump 31 is transferred to the conduit 33a and the control valve 3
2. Supply to the lower chamber 26 of the cylinder unit 16 via the conduit 33d. On the other hand, a control valve connected to the upper chamber 25 of the cylinder unit 16
The port of 32 operates so that the opening area thereof increases with the magnitude of the energizing current, so that the amount of oil flowing out through the conduit 33c is adjusted when the piston 22 moves upward.

That is, since the piston 22 can move only after a certain amount of oil has flowed out of the upper chamber 25, the moving amount of the piston 22 can be adjusted by changing the energizing current of the linear solenoid. Moreover, since the relationship between the magnitude of the energizing current and the amount of spilled oil, that is, the moving amount of the piston can be known in advance, the electronic control unit 4 can predictively calculate the position of the piston 22 from the magnitude of the energizing current to be output and the energizing time. become. Therefore, the energizing current is controlled so that the predicted position quickly reaches the target position. In addition, since the predicted calculation can know the actual movement of the piston 22 in advance, the hydraulic device 3 can be driven while compensating for the response delay.

Then, when it is determined that the target position has been reached, the energization of the linear solenoid is terminated. At this time, the control valve 32 returns to the state of the neutral position 32a, the upper and lower chambers 25 of the cylinder unit 16,
26 is kept oiltight again and the piston 22 is locked in the target position. By this extension, when turning right, the extension mode of the cylinder unit 16 positively causes the vehicle to generate torsional rigidity to the stabilizer 13, and the roll angle φ of the vehicle body is constantly decreased.

In the expansion / contraction mode, the linear solenoid that drives the control valve 32 toward the contracted position 32c is energized. At this time, in the control valve 32, the conduit 33 connected to the upper chamber 25 of the cylinder unit 16
The port connected to c is immediately fully opened to supply the pressure oil from the pump 31 to the upper chamber 25 of the cylinder unit 16 via the pipe 33a, the control valve 32, and the pipe 33c. On the other hand, cylinder unit
The port of the control valve 32 connected to the lower chamber 26 of 16 operates so that its opening area increases with the magnitude of the energizing current,
When the piston 22 tries to move downward, the amount of oil flowing out through the pipe line 33d is adjusted. Therefore, similarly to the case of the extension mode, the piston position is predicted, and when it is determined that the piston 22 has reached the target position, energization is terminated and the piston 22 is fixed at the target position. Due to this contraction, when the vehicle turns to the left, the contraction mode of the cylinder unit 16 positively generates the torsional rigidity of the stabilizer 13 in the vehicle, and the roll angle of the vehicle body decreases steadily.

As described above, when the cylinder unit 16 expands and contracts in accordance with the expansion / contraction target value (when the target value changes quasi-steadily slowly due to slow steering), the roll suppressing effect is exerted, but the rapid steering is performed. When the expansion / contraction speed exceeding the maximum supply amount of pressure oil to the cylinder unit 16 is required, such as when entering the turning state with, the state in which the actual expansion / contraction amount does not reach the target expansion / contraction amount transiently Occasionally, a situation may occur in which the above-described sufficient roll suppression effect is not exhibited.

Therefore, when such a situation is detected, each damping force type shock absorber is in the normal state (Sof
Control for changing from t) to the state (Hard) shown in FIG. 6 is performed. By this operation, the roll rigidity in the transitional period until the stabilizer device 2 reaches a sufficient roll rigidity value can be secured by performing control to increase the damping force of the shock absorber. That is, the response delay of the stabilizer device 2 is compensated by performing the control for increasing the damping force of the shock absorber during the transient period of the rapid steering where the roll suppressing effect cannot be obtained by the stabilizer device 2 alone. A higher roll suppressing effect can be obtained.

 The above is the mechanical operation of the vehicle attitude control device.

Next, FIG. 8 shows a specific control method in this device such as the position of the piston 22 of the cylinder unit 16 (hereinafter, simply referred to as a stroke), the damping force control of the shock absorber, and the timing of their combined control. It will be described in accordance with the flowchart of.

FIG. 8 is a flowchart showing the overall flow of control. This control process is repeatedly executed at a cycle (for example, 8 msec) sufficiently faster than the response time of the hydraulic device 3. Therefore, control that compensates for the response delay of the hydraulic system is possible. Further, this calculation cycle is sufficiently faster than the operating time of the shock absorber damping force varying device 5, and can always be controlled to the optimum state.

In FIG. 8, first, in step 100, the vehicle speed V, the steering angle θ, and the signal of the expansion / contraction switch 43 for knowing the driving state such as turning and going straight are read. In this processing, the following procedure changes depending on whether or not the vehicle is turning. Here, the magnitude of the lateral turning acceleration is used for the determination.

Therefore, in step 110, the turning lateral acceleration G is obtained. This calculation is obtained from the vehicle speed V and the steering angle θ ₁ by a predetermined relational expression G = k ₁ · θ ₁ · V ⁿ (k ₁ , n is a known constant). Note that the steering angle θ ₁ here is the steering wheel 18
From the steering wheel 6 and 10 to the steering wheel, and the steering force is absorbed by the twist of the steering wheel or the like and does not contribute to steering. It is a value subtracted from the steering angle θ read in step 100 (when the result becomes negative, it is set to zero). Further, the size of the steering dead zone is determined by the specifications of the vehicle and the like, and the value becomes smaller as the vehicle speed becomes larger as the vehicle speed becomes lower, and is calculated by a map obtained in advance.

Based on the value of the lateral turning acceleration G, it is determined in step 120 whether or not the vehicle is turning. That is, if the turning lateral acceleration G is G ≠ 0, it is judged that the vehicle is truly turning, and if G = 0, it is judged that the vehicle is not turning. If it is determined in this determination that the vehicle is turning, the process proceeds to step 130 and thereafter to perform processing during turning.

First, at step 130, a target expansion / contraction amount (target stroke) S _T of the cylinder unit 16 required to eliminate the rolling roll is obtained. This calculation is performed using a relational expression determined by the specifications of the vehicle, the rigidity value of the stabilizer, and the like. That is, when the stabilizer is used in a region having a linear spring action, the target stroke amount S is obtained by S = k ₂ · G (k ₂ is a constant) and the cylinder unit
The target stroke S _T is obtained by the calculation of S _T = S _O ± S using the value S _O for obtaining the neutral position of 16. The sign of the above formula means that when the cylinder unit 16 is mounted on the right side (driver's side) of the vehicle as shown in FIG. ) Is taken, and- (minus) is taken to mean that the cylinder is contracted when turning left.

When the target stroke S _T is set using the relationship of S = k ₂ · G, the cylinder unit 16 is adjusted so as to follow the target stroke S _T up to the maximum stroke range, so that in the range up to a predetermined turning lateral acceleration, It is possible to control the roll angle of the vehicle to zero.

Then, calculating the change rate _T of the change rate _T of the target stroke S _T proceeds to step 140. This calculation, for example, because the target stroke S _T determined in the previous calculation (n-1) and the current calculated target stroke S _T (n), the following equation _{{S T (n) -S T} (n-1) } / ΔT = _T based on the difference calculation. Here, ΔT is a calculation cycle.

Now, next, in step 150, the state of the control output to the shock absorber damping force varying device 5 in the previous calculation cycle is determined. This is a judgment process necessary for the following continuation or return (to the Soft state) process.
If it is determined that the damping force is in the Hard state in the previous cycle, the process proceeds to step 160.

In step 160, the change speed _{T of the} target stroke obtained in step 140 is compared with the maximum expansion / contraction speed _AM that the cylinder unit 16 can achieve. Here, _AM is the maximum amount of oil that the hydraulic device 3 can supply (a known value that is determined by the discharge flow rate of the pump 31 and the passing flow rate when the control valve 32 is fully opened).
Is a value obtained by dividing the pressure receiving area of the piston 22 of the cylinder unit 16 by a known value. And by this judgment, _T > _AM
If it is determined to be a sharp turn, step 17
Proceed to 0,180 to perform processing to set the damping force to Hard. Specifically, the motor 90 of FIG. 7 is energized to rotate the control rod 73 to bring it to the state of FIG. In addition, step
The determination _T > _{AM of} 160 means detection of a sharp turning state in which the stabilizer device 2 cannot effectively suppress the roll.

If it is determined in step 160 that _T ≤ _AM , the process proceeds to step 190. Here, the target stroke S _T and the actual position of the piston 22 (referred to as the actual stroke) S _A are compared with a determination threshold ΔS. This is for detecting the state where the actual stroke S _A is apart from the target stroke S _T due to the influence of the previous sharp turn even if the steering speed is slowed down. In that case, a sufficient roll suppressing effect cannot be obtained, and control is performed to increase the damping force of the shock absorber (set to Hard), and the process proceeds to steps 170 and 180.

When | S _T −S _A | ≦ ΔS in the judgment of 190,
The stabilizer device 2 is in a state of starting to exert a sufficient roll restraining effect in the gentle steering state, and it is no longer necessary to rely on the damping force of the shock absorber. There step
The counter is incremented by 200, and in step 210 it is judged whether the counter value is larger than T _O or not, and the process returns.

This processing is performed for the following reasons. That is, if the damping force is immediately returned to the Soft state even if the return condition of step 190 is satisfied, unnatural movement such as inadvertent reciprocation occurs because the roll restraining control by the stabilizer device 2 is in the transition period. It is inconvenient. Therefore, it is necessary to wait for T _O after the return condition is satisfied and then perform a delay process to return the damping force to Soft. Therefore, only if the first recovery condition is T _O time its state from the satisfied continues at step 190, performs a control of setting the damping force of the step 230, 240 Soft.

If it is determined in step 150 that the control state in the previous calculation cycle is the damping force Soft, the process proceeds to step 220. Here, similarly to step 160, it is determined whether or not the target stroke change speed _T exceeds the maximum expansion / contraction speed _AM. If it exceeds, the process proceeds to step 170 and below in order to change the damping force to Hard, and otherwise. First, the process proceeds to step 230 and the subsequent steps.

If it is determined in step 120 that the vehicle is not turning, the process proceeds to step 250 and the control target value S _T of the cylinder unit 16 is set to the neutral value S _O. Further, in order to secure the riding comfort, steps 230 and 240 for setting the damping force of the shock absorber to Soft are performed. The process of setting the damping force to Soft is to energize the motor 90 of FIG. 7 to rotate the control rod 73 to the state of FIG.

As described above, after the damping force of the shock absorber is controlled to Hard or Soft in Step 180 or 240, the process proceeds to Step 260 and the piston position control (stroke control) of the cylinder unit 16 is performed. In this process, the position S _A of the piston 22 of the cylinder unit 16 is changed to the step 13
This is a control for driving the hydraulic device 3 so as to match the target value S _T obtained by 0 or 250.

In this embodiment, the following predictive control is performed. Current value to control valve 32 and cylinder unit 16 at that time
Since the relationship of the flow rate flowing out of the piston is known in advance, the predicted value S _C of the piston position S _A is obtained based on the relationship. Then, the hydraulic device 3 is controlled so that the difference between the predicted value S _C and the target value S _T becomes zero. Further, the cylinder unit 16 is equipped with a telescopic switch 43 for detecting the neutral passage of the piston, and the switch signal causes S _C
Is corrected to obtain a value extremely close to the actual piston position S _A.

As described above, by combining the roll suppression control by the stabilizer device 2 and the control for increasing the damping force by using the shock absorber damping force varying device 5 at the initial stage of the transient state of the sharp turn, the control shown in FIG. As indicated by the solid line A, the roll angle of the vehicle body during turning does not change suddenly and can be suppressed to a sufficiently small value near zero.

Further, when the roll restraint control by the stabilizer device is started at the time of a sharp turn and the control end condition in which the difference between the actual stroke and the target stroke of the cylinder unit becomes smaller than a predetermined value is determined, the damping force of the shock absorber is reduced. Return to the side. As a result, at the end of the transitional state (when the control end condition is in effect), where the end of the stabilizer control is eliminated and the roll is properly suppressed, the damping force of the vehicle returns to the low side, which causes over-control of the roll rigidity. It is possible to suppress the occurrence of rolling in the reverse direction of the running vehicle.

As shown in the same figure, even if the damping force control of the shock absorber is simply kept hard during turning, as shown by the broken line B in FIG. The roll restraining effect is obtained at the initial stage of the steering turning, but as the turning continues, the suspension spring is displaced and the roll increases. On the other hand, with the conventional stabilizer control alone, as shown by the chain line C, the response at the time of sudden steering is slow, so that a sufficient roll suppressing effect is not exhibited in the initial stage of turning and a sufficient roll suppressing effect cannot be obtained. Also, since the movement of the cylinder unit does not correspond to the actual change of the lateral acceleration of turning, in a remarkable case, a rolling back phenomenon accompanied by rolling in the opposite direction occurs.

However, if the composite control according to the present invention is performed, FIG.
As shown by the solid line A, the defective portions of such two control devices are complemented with each other to obtain a more ideal roll suppressing effect. The dotted line D in FIG. 9 (d) shows the case where there is no control.

Further, with regard to the damping force varying device 5 of the shock absorber, in this embodiment, the DC motor is used to rotate the control rod to change the orifice diameter.
If the orifice diameter can be changed by electrical means,
Any configuration may be used, such as direct drive of the control rod by a solenoid (rotational movement as in the present embodiment or vertical linear movement).

Regarding the stabilizer device 2, it has been described that the expansion / contraction control of the cylinder unit is performed by predictive control using an expansion / contraction switch, but a sensor for detecting the piston position of the cylinder unit is configured by a method such as a differential transformer or capacitance detection. Then, the actual expansion / contraction amount of the cylinder unit may be detected, and feedback control using the sensor value may be performed.

In this embodiment, the state of the damping force control is determined by comparing the change speed _{T of the} target stroke and the maximum expansion / contraction speed _AM . However, the change in the steering angle θ (steering speed) is determined, and the value is predetermined. The damping force may be set to Hard as a sudden steering when it becomes larger than the threshold value _O.

Return processing steps 200 and 210 of FIG. 8 may be set to the default or T _O = 0 by suspension setting of the vehicle. If omitted, of course, steps 170 and 23
Counter processing of 0 is also unnecessary.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an outline of the present invention, FIGS. 2 and 3 are configuration diagrams showing a configuration of an embodiment of the present invention, and FIG. 4 is an explanatory diagram showing a hydraulic circuit and an electric circuit of the embodiment. , FIG. 5 (A),
(B), (C) and FIGS. 6 (A), (B), (C) are explanatory views of the shock absorber of the embodiment, FIG. 7 is a perspective view of a damping force changing actuator, and FIG. 8 is electronic control. FIG. 9 is a flow chart showing the control of the apparatus, FIG. 9 is a timing chart showing the state of the control, and FIG. 10 is a timing chart showing the state of the control of the conventional technique. 2 ... Stabilizer device, 3 ... Hydraulic device, 4 ... Electronic control device, 5
… Shock absorber damping force variable device, 13… Stabilizer bar, 16… Cylinder unit, 41… Vehicle speed sensor, 42… Steering angle sensor, 43… Stroke expansion switch, 51, 52… Damping force control actuator.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshio Onuma 1 Toyota Town, Toyota City, Aichi Prefecture, Toyota Motor Co., Ltd. (72) Inventor Hidenori Ichimaru 1, Toyota Town, Aichi Prefecture, Toyota Motor Co., Ltd. ( 72) Inventor Hiroyuki Ikemoto 1 Toyota-cho, Toyota-shi, Aichi Within Toyota Motor Corporation (56) Reference JP-A-60-157910 (JP, A) JP-A-61-146612 (JP, A) JP-A-SHO 60-213514 (JP, A) JP-A-63-61619 (JP, A)

Claims (1)

(57) [Claims] 1. A stretchable cylinder device is provided between a vehicle stabilizer and a vehicle, and the stretchable control of the cylinder device is performed based on a target control value according to a turning state of the vehicle to suppress rolls generated in the vehicle. A suspension control device for a vehicle equipped with a stabilizer control, further comprising: a damping force adjusting means capable of adjusting a damping force of a suspension of a vehicle in at least two stages in accordance with a command from the outside; A traveling state signal generating means for generating a state signal, a sudden turning determination means for determining the start of a rapid turning state based on the traveling state signal, and a case where the rapid turning determination means determines that the rapid turning state has started Is a command to change the damping force of the suspension to a higher side in order to suppress the roll that occurs at the beginning in a sharp turning state, A change means for outputting to a damping force adjusting means, and a target control value calculating means for calculating a target control value for adjusting the expansion / contraction amount of the cylinder device so as to suppress the roll generated in the vehicle based on the traveling state signal. And an expansion / contraction amount detecting means for obtaining an actual expansion / contraction amount of the cylinder device, comparing the target control value with an actual expansion / contraction amount of the cylinder, and only after the start of a sudden turn, the target control value and the actual expansion / contraction are calculated. A control end condition in which the difference from the amount becomes smaller than a predetermined value is determined, and based on this control end condition, a command for returning the damping force of the vehicle from the higher side to the lower side is output to the damping force adjusting means. A suspension control device for a vehicle, comprising: