JP2552359B2 - Vehicle dynamic characteristics control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a yaw rate control by a hydraulic actuator such as an auxiliary steering control system or an active suspension control system for auxiliary steering at least one of front wheels and rear wheels during steering of front wheels. The present invention relates to a vehicle dynamic characteristic control device that optimally controls vehicle dynamic characteristics such as lateral acceleration and vehicle body roll.

(Prior Art) As an example of this type of rear wheel steering control system (an example of a vehicle dynamic characteristic control device), there is a system previously proposed by the applicant of the present application in Japanese Patent Application No. 63-165932.

This rear-wheel steering control system determines a target rear-wheel steering angle θ _R based on the front-wheel steering angle θ _F and the vehicle speed V, and steers the rear wheels in-phase or anti-phase with respect to the front wheels. 2W
Compared to the S car), the side slip angle of the car body is suppressed to improve steering stability and the yaw rate rise is increased to improve responsiveness.

(Problems to be Solved by the Invention) In the preceding rear wheel steering control system, the supply of the control hydraulic pressure is shut off at a predetermined fail time, and the hydraulic pressure of the actuator is gradually reduced by utilizing the oil leak in the valve. A normally closed cut valve is shown to prevent sudden changes in vehicle behavior during a failure.

However, if the harness that supplies power from the ignition switch to the constant voltage circuit of the rear wheel steering control unit is temporarily disconnected, or if the ignition switch is turned OFF-ON within a short time, a large hydraulic pressure drop will occur in the actuator. However, there is a problem that the vehicle behavior changes suddenly due to the steep turning of the rear wheels due to this drop.

That is, as shown in FIG. 7, the cut valve closes after the power is turned off, and the actuator oil pressure gradually decreases, but the power is turned on and the cut valve is immediately cut off within a short time when the oil pressure is not sufficiently decreased. When is opened, the initial target rear wheel steering angle θ _RO is set to θ _RO = 0, so that the actuator hydraulic pressure drops to zero at once and a large hydraulic pressure drop occurs.

The present invention has been made in view of the above-mentioned problem, and in a vehicle dynamic characteristic control device having an opening / closing means capable of interrupting the supply of control hydraulic pressure, the energization from the power source is restored from the temporary interruption to the conduction. It is an object to prevent sudden changes in vehicle behavior at the time of disconnection.

(Means for Solving the Problems) In order to solve the above problems, in the vehicle dynamic characteristic control device of the present invention, when the power is restored from the temporarily disconnected state to the conductive state, the open state of the opening / closing means is kept for a predetermined time and the opening operation is delayed. The means.

That is, as shown in the claim correspondence diagram of FIG. 1, a target control amount for obtaining an optimum vehicle dynamic characteristic is determined based on predetermined input information, and a control hydraulic pressure for obtaining this target control amount is supplied to the hydraulic actuator a. The dynamic characteristic control means b, the opening / closing means c capable of interrupting the supply of the control hydraulic pressure to the hydraulic actuator a when the power is turned off or a predetermined failure, and the time during which the power is turned on again after the power is turned off. In the following cases, a temporary disconnection detecting means d for detecting a temporary disconnection state, and a closing command for the opening / closing means c when the power is turned off,
When the temporary disconnection detecting means d detects that the power has been restored from the temporary disconnection state to the conductive state, the opening / closing control means e delays the set delay time from the detection of the power recovery and outputs an opening command to the opening / closing means c. And are provided.

(Operation) If the harness that supplies power is temporarily disconnected or if the ignition is turned OFF-ON within a short time,
In the temporary disconnection detection means d, power is turned on again from power off
When the condition that the period of time becomes equal to or less than the set time for a short time is satisfied, it is detected that the communication is temporarily stopped.

When the power supply is turned off, the opening / closing control means e outputs a closing command to the opening / closing means c, and when the temporary disconnection detecting means d detects that the power has been restored from the temporary disconnection state to the conductive state, it is set from the time when the power source recovery is detected. The opening command is output to the opening / closing means c after a delay time.

That is, the opening / closing means c is closed after the power is turned off, and the hydraulic pressure of the actuator is gradually decreased due to the oil leak from that time, but the closed state of the opening / closing means c is maintained for a delay time even after the power is turned on. As a result, the actuator hydraulic pressure is sufficiently reduced during this period.

Therefore, even if the opening / closing means c is opened after the oil pressure has dropped, a small oil pressure drop occurs, so that sudden changes in vehicle behavior are prevented.

(Example) Hereinafter, the Example of this invention is described in detail based on drawing.

FIG. 2 is a diagram showing an overall configuration of a four-wheel steering vehicle equipped with a rear wheel steering control system (an example of a vehicle dynamic characteristic control device) of the embodiment.

 First, the configuration will be described.

In Fig. 2, 1L and 1R are left and right front wheels, 2L and 2R are left and right rear wheels,
3 is a handle. The front wheels 1L and 1R can be steered via the steering gear 4 by the steering wheel 3, respectively, and the rear wheels 2L and 2R can be steered.
Each R can be steered by the rear wheel steering actuator 5.

The rear wheel steering actuator 5 (hydraulic actuator) is a spring center type hydraulic actuator,
When hydraulic pressure is supplied to the chamber 5R, only the steering angle proportional to the pressure is applied to the rear wheels.
When 2L and 2R are steered to the right and hydraulic pressure is supplied to the chamber 5L, the rear wheels 2L and 2R are steered to the left by a steering angle proportional to the pressure.

An electromagnetic proportional rear wheel steering control valve 6 for controlling the hydraulic pressure to the actuator chambers 5L, 5R is provided, and this valve 6 has a structure in which variable throttles 6a, 6b, 6c, 6d are connected in a bridge, and a pump 7 is connected to this bridge circuit. , Reservoir 8 and actuator chamber
Connect oil paths 9 and 10 from 5L and 5R respectively.

The control valve 6 is further provided with solenoids 6L and 6R, and when the solenoids 6L and 6R are OFF, the variable throttles 6 are respectively provided.
When a, 6b and 6c, 6d are fully opened, both actuator chambers 5L, 5R are in a non-pressure state, and when the solenoid 6L or 6R is turned on by the dithered drive current I _L ^* or I _R ^* , the variable throttle 6c, 6d or 6a , 6b to the opening corresponding to the current value and the actuator chamber 5L or 5R
The hydraulic pressure should be supplied according to the current value of the dithered drive current I _L ^* or I _R ^* . As described above, this hydraulic pressure steers the rear wheels 2L, 2R in the corresponding direction by an angle corresponding to the value.

Oil passages 9 and 10 between the electromagnetic proportional type rear wheel steering control valve 6 and the rear wheel steering actuator 5 (the oil passages before and after the cut valve 20 are 9-1, 9-2 and 10-1, 10-, respectively). 2)
In the middle of the
(Opening / closing means) is inserted.

This cut valve 20 is a normally closed type and the ignition OF
When the solenoid drive current I _F is not supplied to the solenoid 20a at the time of F or fail, between the oil passages 9-1, 9-2 and 1
Blocked between 0-1,10-2 is when being conducted rear wheel steering control properly, when the solenoid drive current I _F is supplied, while the oil passage 9-1, 9-2 And 10-1 and 10-2 are connected.

The fail time when the cut valve 20 is closed means that the microcomputer 6 has runaway, the sensor is abnormal, or the solenoids 6L and 6R of the control valve 6 are broken or short-circuited. Turn on 21.

Applying a dithered drive current I _L ^* or I _R ^* to the control valve solenoids 6L and 6R, and cutting valve solenoids
Apply solenoid drive current I _F to 20a, or alarm lamp 2
The rear wheel steering control unit 30 that applies an ON-OFF signal to 1 determines the steering wheel steering angle sensor 40 that detects the steering wheel steering direction and the steering wheel steering angle θ, and the neutral position of the steering wheel as sensors that provide input information. Steering wheel neutral position sensor 41 detected by ON signal in the steering angle range
A vehicle speed sensor 42 for detecting the vehicle speed V, an ignition switch 43 as a switch for supplying power to the constant voltage circuit of the rear wheel steering control unit 30, and the like are connected.

And, in this rear wheel steering control unit 30,
As shown in the block circuit diagram of FIG. 3, as internal circuits, an A / D converter 30a, a neutral steering angle estimated value arithmetic circuit 30b, a backup memory 30c, a front wheel steering angle arithmetic circuit 30d, a rear wheel steering angle arithmetic circuit 30e. , D / A converter 30f, θ _R -I converter 30g,
It has a dither setting circuit 30h, a solenoid drive circuit 30i, an abnormality detection circuit 30j, a fail safe circuit 30k, a solenoid drive circuit 30l, a display drive circuit 30m, a self-diagnosis circuit 30n, and a backup memory 30o.

 Next, the operation will be described.

FIG. 4 shows the rear wheel steering control started through the cut valve opening / closing control process by supplying power to the rear wheel steering control unit 30 by turning on the ignition switch 43 or restoring the power harness from a temporary disconnection to a conductive state. It is a flow chart which shows a flow of operation and fail safe operation.

* Cut valve opening / closing control process In step 50, it is determined whether or not the power is ON for the first time, and if the control is started for the first time, the process proceeds to step 51 and thereafter, and if it is the second time and thereafter, proceeds to step 57.

In step 51, the initial target rear wheel turning angle θ _RO is set to θ _RO = 0 (zero) as an initialization process.

In step 52, the timer value T and the set timer value T from when the power is turned off are checked to determine whether the power is turned on by a normal ignition operation or the power is returned to a conductive state from a temporary interruption due to a temporary disconnection. is determined by comparison with _0, in the case of T ≦ T _0, the program proceeds to determine the time of power returns to step 53 and subsequent by transient disconnection or the like, in the case of T> T ₀ is
It is determined that the power is turned on by the normal ignition operation, and the process proceeds to step 57.

In step 53, the stored target rear wheel turning angle θ _RM when the power was turned off last time is read.

In step 54, it is judged whether or not the memory target rear wheel turning angle θ _RM is equal to or greater than the valve opening delay threshold value K of the cut valve 20, and if θ _RM <K, the process proceeds to step 55 to set the delay time. Immediately, a solenoid drive current _IF is output to the cut valve solenoid 20a by an ON signal that opens the cut valve 20.

On the other hand, when θ _RM ≧ K, a predetermined delay time t ₀ sufficient to reduce the hydraulic pressure drop is set, and after waiting the delay time t ₀ , the cut valve 20 is opened to the cut valve solenoid 20a. The solenoid drive current I _F is output according to the open ON signal.

In step 57, it is determined whether or not the fail command is output when the abnormality detection circuit 30j detects any abnormality, and when the fail command is not output, the rear wheel steering control operation after step 58 is performed. If the fail command is output, the fail safe operation from step 64 onward is performed. It should be noted that steps 50 to 57 correspond to temporary disconnection detecting means and opening / closing control means.

* Rear wheel steering control operation In step 58, the steering wheel steering angle θ, the vehicle speed V, and the stored neutral steering angle estimated value θ _CM are read.

In step 59, the front wheel steering angle θ _F is calculated by the following equation based on the steering wheel steering angle θ and the stored neutral steering angle estimated value θ _CM .

θ _F = | θ−θ _CM | In step 60, the target rear wheel turning angle θ _R is calculated based on the vehicle speed V and the front wheel steering angle θ _F.

In step 61, the target rear wheel turning angle θ _R is converted into a drive current I _L or I _{R according} to a previously given θ _R −I characteristic table.

In step 62, the dither-equipped drive current I _L ^* or I _R ^* obtained by adding dither according to a predetermined amplitude and frequency to the drive current I _L or I _R obtained in step 61 is output to the control valve solenoid 6L or 6R. .

In step 63, the solenoid driving current I _F according to ON signal to the valve solenoid 20a opens the cut valve 20 is output.

* Fail-safe operation In step 64, the solenoid drive current I _F by the OFF signal that closes the cut valve 20 to the valve solenoid 20a
Is output.

In step 65, a lighting signal (ON) is output to the alarm lamp 21.

In step 66, it is checked whether the elapsed time ΔT from the failsafe command has reached a predetermined time ΔT ₀ (for example, 150 msec), and if ΔT ≧ ΔT ₀ , then in step 67 the dither of the solenoid 6L or 6R of the control valve 6 is performed. Drive current
A command to turn off I _L ^* or I _R ^* is output.

* Power-off process If it is determined in step 68 that the power is off, the timer used in step 52 is started in step 69, and the latest target rear wheel steering angle θ _R is stored in step 70. The steering angle θ _RM is stored, and in step 71, the solenoid drive current I _F is output to the valve solenoid 20a by an OFF signal for closing the cut valve 20.

As described above, the rear wheel steering control system according to the embodiment has the features listed below.

If the harness that supplies power to the constant voltage circuit of the rear wheel steering control unit 30 via the ignition switch 43 is temporarily disconnected, or if the ignition switch 43 is turned OFF-ON within a short time, the power is switched from the temporary disconnection state to the conduction state. Is restored, the temporary disconnection condition determined in step 52 is satisfied, and step 52 to step 53 → step
If the stored target rear wheel steering angle θ _RM is equal to or greater than the predetermined threshold value K when the power is restored from the temporary disconnection state to the conduction state according to the determination in step 54, the open command output to the cut valve 20 is output in step 56. Is delayed by a delay time t ₀ .

By this opening delay control of the cut valve 20, as shown in the time chart of FIG. 6, the cut valve 20 is closed from the time t ₁ when the power is turned off, and from that time t ₁ the control oil pressure of the actuator 5 is gradually increased due to the oil leak. But the power is
Even after the switch is turned on, the control valve oil pressure is sufficiently reduced by keeping the closed state of the cut valve 20 for the predetermined delay time t ₀ .

Therefore, a large hydraulic pressure drop does not occur unlike when opening and closing the cut valve 20 in conjunction with power ON-OFF, and even if the cut valve 20 is opened after the hydraulic pressure has sufficiently decreased, a small hydraulic pressure drop will occur. A sudden change in vehicle behavior is prevented.

When the memory target rear wheel turning angle θ _RM is small, even if the cut valve 20 is opened immediately, the control oil pressure of the actuator 5 is low, so there is a large oil pressure drop without delaying the opening of the cut valve 20. Absent.

In the rear wheel steering control operation, for example, as shown in FIG. 5, the rear wheels are momentarily controlled to be in a reverse phase with respect to the front wheel steering angle θ _F , and then are controlled to be in the same phase. When controlled, the cornering force is positively added in the yaw direction to improve the yaw rate rise, and after sufficient yawing is obtained, the rear wheels are steered to the in-phase side. By suppressing the increase in yaw rate, it is possible to suppress the side slip angle of the vehicle body, which increases steering stability and high responsiveness. It is especially effective in the low and medium speed range.

In fail-safe operation, the oil pressure is cut by the cut valve 20, and then the operation of returning the rear wheel to the neutral position gradually is performed by utilizing the oil leak in the cut valve 20. A sudden change in behavior is prevented.

Although the embodiment has been described above with reference to the drawings, the specific configuration and control contents are not limited to this embodiment.

For example, although the example of the rear wheel steering control system is shown as the vehicle dynamic characteristic control device in the embodiment, the control hydraulic pressure such as the auxiliary steering control system and the active suspension control system that steer the front and rear wheels during steering of the front wheels is used. Needless to say, it can be applied to any system having a fail means capable of interrupting supply.

Further, the delay time t ₀ for opening the cut valve may be variable depending on the timer value T for turning off the power and the size of the stored target rear wheel turning angle θ _RM .

(Effects of the Invention) As described above, in the present invention, in the vehicle dynamic characteristic control device having the opening / closing means capable of cutting off the supply of the control hydraulic pressure, the time for turning the power on again after the power is turned off is short. When the time is less than the set time, the temporary disconnection detection means that detects a temporary disconnection state, and a closing command is output to the opening / closing means when the power is off, and the temporary disconnection detection means restores power from the temporary disconnection state to conduction. When it is detected, the device is provided with an opening / closing control unit that outputs an opening command to the opening / closing unit by delaying a set delay time from the detection of the power supply recovery, so that the power supply from the power supply is electrically connected due to a temporary interruption. The effect that it is possible to prevent a sudden change in vehicle behavior at the time of a temporary disconnection in which the vehicle recovers

[Brief description of drawings]

FIG. 1 is a diagram for responding to a complaint of a vehicle dynamic characteristic control device of the present invention, FIG. 2 is a diagram showing an overall configuration of a four-wheel steering vehicle equipped with a rear wheel steering control system, and FIG. 3 is a rear wheel steering control system. FIG. 4 is a block circuit diagram of the rear wheel steering control unit, FIG. 4 is a flowchart showing a flow of rear wheel steering control operation and fail-safe operation, FIG. 5 is a time chart showing an example of rear wheel steering control, and FIG. Time chart showing the opening / closing control operation of the cut valve when the power is temporarily cut off in the system, and FIG. 7 shows the opening / closing control operation of the cut valve when the power is temporarily cut off in the conventional system. It is a time chart. a ... hydraulic actuator b ... dynamic characteristic control means c ... opening / closing means d ... target control amount storage means e ... temporary interruption detecting means f ... opening / closing control means

Claims (1)

(57) [Claims] 1. A dynamic characteristic control means for deciding a target control amount for obtaining an optimum vehicle dynamic characteristic on the basis of predetermined input information and supplying a control hydraulic pressure for obtaining this target control amount to a hydraulic actuator, and for turning off the power supply, An opening / closing means capable of cutting off the supply of the control hydraulic pressure to the hydraulic actuator at the time of a predetermined failure, and a temporary disconnection state is detected when the time for which the power is turned on again after the power is turned off is shorter than a set time. When the temporary disconnection detecting means and the closing command is output to the opening / closing means when the power is turned off, and when the temporary disconnection detecting means detects that the power is restored from the temporary disconnected state to the conductive state, the delay set after the power recovery is detected. A vehicle dynamic characteristic control device comprising: an opening / closing control unit that outputs an opening command to the opening / closing unit after delaying by a time.