JP3425729B2 - Vehicle behavior control device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a behavior control device suitable for attitude control for stabilizing the turning behavior of a vehicle at the time of turning, and particularly to a behavior of a vehicle in which an end timing of the behavior control by an automatic brake is appropriately set. Regarding the control device.

[0002]

2. Related Background Art A turning control device for a vehicle, which controls the turning motion of the vehicle by applying a braking force difference between predetermined wheels when the vehicle turns, is disclosed in, for example, Japanese Patent Application Laid-Open No. 8-332932.
It is disclosed in the publication. In this turning control device, the braking pressures of the wheel brakes on the wheels to be controlled, that is, the left and right diagonal wheels are controlled to generate a braking force difference between these wheels, thereby matching the actual yaw rate of the vehicle with the target yaw rate. The turning motion of the vehicle is controlled so as to cause the movement. Further, the magnitude of the braking force between the wheels to be controlled is determined based on the deviation between the target yaw rate and the actual yaw rate. Then, if the braking force of these control target wheels, that is, the braking pressure of the wheel brake is maintained for a certain period of time or more, the braking force control is ended, and after the braking force control is ended, the control is performed. By gradually reducing the braking pressure of the target wheel, the difference in braking force is gradually eliminated to avoid sudden changes in vehicle behavior.

[0003]

By the way, in the turning control of the vehicle of this type, that is, the control for correcting the motion state of the vehicle, even if the turning behavior of the vehicle is stable, it largely depends on the turning control. In some cases, it is not appropriate to simply compare the target yaw rate of the vehicle with the actual yaw rate and determine the end of the turning control from these deviations.

Therefore, even if the braking pressure of the wheels is maintained for a certain period of time or longer, more specifically, the yaw rate deviation is small during the turning control, so that the braking pressure of the wheels does not change. Even if such a situation continues for a certain period of time or more, it may not be appropriate to terminate the braking force control at this point. That is, if such a situation is brought about by the turning control itself, the behavior of the vehicle may change undesirably due to the end of the braking force control.

The present invention has been made based on the above-mentioned circumstances, and its purpose is to make a simple and accurate determination of the end of turning control, and further, the braking force control based on the determination. It is an object of the present invention to provide a vehicle behavior control device that does not impair the stable turning behavior of the vehicle even when the above-mentioned is canceled.

[0006]

In order to achieve the above object, a vehicle behavior control device according to a first aspect of the invention operates independently of a driver's braking operation, and applies a braking force acting on a predetermined wheel. Adjustable braking force adjusting means, running state detecting means for detecting and outputting the running state of the vehicle, and actual moving state detecting means for detecting and outputting the actual moving state of the vehicle,
Set the target motion state of the vehicle based on the running state, and increase or decrease the target control amount for applying the braking force difference between the predetermined wheels so that the actual motion state matches the target motion state when the vehicle turns.
And a control unit for controlling the operation of the braking force adjusting unit according to the target control amount. The control means in the vehicle behavior control device according to the first aspect terminates the control when the state in which the target control amount is equal to or less than the predetermined value continues for the predetermined time.

According to the vehicle behavior control device of claim 1,
When turning, the braking force on a predetermined wheel is automatically controlled,
A braking force difference is applied between these wheels so that the actual motion state of the vehicle matches the target motion state. That is, the target control amount in this case is calculated as a control amount for generating the braking force difference necessary for controlling the vehicle motion state.

On the other hand, if the vehicle is recovering the steady turning motion state, a large braking force difference between the predetermined wheels becomes unnecessary, and in such a situation, the target control amount also tends to decrease. Therefore, if the target control amount is continuously less than or equal to the predetermined value, there is little need to control the motion state of the vehicle, and the control for applying the braking force difference is also terminated. The vehicle behavior control device according to claim 2 includes an actual braking pressure detection unit that detects and outputs an actual braking pressure that acts on a predetermined wheel, and the control unit determines the actual braking pressure based on the target control amount. Feedback control is performed so as to match the target braking pressure. In this case, since the deviation between the determined target braking pressure and the actual braking pressure is taken into consideration in the braking pressure control system, control that accurately reflects the degree of response of the actual braking pressure to the command from the control means is performed. Be seen.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a vehicle behavior control device of the present invention will be described below with reference to the drawings. First, referring to FIG. 1, there is schematically shown a configuration of a brake system in a vehicle 1 to which a vehicle behavior control device according to an embodiment is applied. The vehicle 1 is, for example, a large vehicle such as a truck or a bus, and therefore, the left and right rear wheels WRL and WRR that are drive wheels are both parallel two-wheel types.
On the other hand, the left and right front wheels WFL and WFR, which are steering wheels, are of the normal type.

The brake system of the vehicle 1 is composed of an air-over hydraulic brake which operates the hydraulic brake by utilizing air pressure. That is, the wheel cylinders 2 provided on the respective wheels WFL, WFR, WRL, and WRR are adapted to actuate a wheel brake (not shown) in response to the supply of braking pressure, that is, hydraulic pressure. Each wheel cylinder 2 has a hydraulic line 3
Are connected to each other, and these hydraulic lines 3
An air-over hydraulic booster 4 for converting air pressure into hydraulic pressure is connected to each. A pneumatic line 8 extends from each air-over-hydraulic booster 4, and each pneumatic line 8 is connected to an outlet port of a double check valve 12, respectively. A pressure control valve 10 is inserted in each pneumatic line 8.

A supply pipeline 13 is connected to one inlet port of each double check valve 12, and these supply pipelines 13 include two relay valves 14.
Two are connected to each. That is, the two supply pipelines 13 on the front wheels WFL and WFR sides are respectively connected to one relay valve 14, and the two supply pipelines 13 on the rear wheels WRL and WRR sides are respectively connected to the other relay valve 14. It is connected. Furthermore, from each relay valve 14, the air supply line 2
4 respectively extend, and these air supply lines 24 are connected to the corresponding air tanks 6, respectively. That is, the pneumatic line from one inlet port of the double check valve 12 to the air tank 6 via the relay valve 14 is shared by the front wheel side and the rear wheel side. In addition,
Air is supplied from a compressor to these air tanks 6, and the compressor is driven by an engine.

Further, signal pressure lines 16 are connected to the input ports of each relay valve 14, and these signal pressure lines 16 are connected to the corresponding air tank 6 via a dual type brake valve 18. There is. Therefore,
The signal pressure line from the brake valve 18 to the relay valve 14 via the signal pressure line 16 is also shared by the front wheel side and the rear wheel side.

On the other hand, an air supply pipe 20 is connected to the other inlet port of each double check valve 12, and each of the two air supply pipes 20 is connected to two air supply valves 22. . That is, the two air supply conduits 20 corresponding to the left and right wheels on the front wheel side are respectively connected to one air supply valve 22, and the two air supply conduits 20 corresponding to the left and right wheels on the rear wheel side are connected to the other air supply. Each is connected to the valve 22. That is, the downstream portion of each air supply line 24 is branched,
The relay valve 14 and the air supply valve 22 on the corresponding side are respectively connected. Therefore, double check valve 12
The air supply line from the other inlet port to the air tank 6 via the air supply valve 22 is also shared by each of the front wheel side and the rear wheel side.

In the brake system of the vehicle 1, a service brake circuit is formed from the pneumatic pressure line, the signal pressure line and the hydraulic pressure line described above, and an automatic brake circuit is formed from the air supply and pneumatic pressure lines and the hydraulic pressure line. ing. In the service brake circuit, as is well known, when the driver depresses the brake pedal 26, a signal pressure according to the depressing force and the amount of depression is supplied to the input port of each relay valve 14. The relay valve 14 is opened by the signal pressure thereof, and at the same time, the opening degree is controlled according to the magnitude of the signal pressure, whereby the air tank 6 is connected to the air supply line 2
4, fluid pressure, that is, air pressure is supplied to the air-over-hydraulic booster 4 via the supply pipeline 13 and the pneumatic pipeline 8. Then, the air pressure is converted into hydraulic pressure by the air over hydraulic booster 4, and the wheel cylinder 2 operates the wheel brake by the hydraulic pressure raised here, so that the braking force is applied to each wheel WFL, WFR, WFL, WFR. Is generated. If the driver weakens the pedal effort of the brake pedal 26 or reduces the amount of depression, the brake valve 18
The signal pressure supplied to the relay valve 14 via is reduced by that amount, and when the depression of the brake pedal 26 is completely released, the supply of the signal pressure is completely stopped. Therefore, as the signal pressure is reduced or stopped, the air pressure supplied to the air over hydraulic booster 4 via the relay valve 14 is also reduced or stopped.

On the other hand, in the automatic brake circuit, the braking force can be generated independently of the driver's braking operation. That is, each air supply valve 22 consists of a valve unit containing two solenoid valves, and these two solenoid valves are
Both consist of a 2-position electromagnetic directional control valve. And
The solenoid of each solenoid valve is electrically connected to an electronic control unit, that is, an ECU 28 that serves as control means. In FIG. 1, the ECU 2 is shown for convenience of drawing.
The connection between 8 and the air supply valve 22 is shown by only one signal line. More specifically, each air supply valve 22 has an inlet port, two outlet ports, and an exhaust port, and the air supply pipe 24 described above is connected to the inlet port, and each air supply valve 22 As shown in FIG. 1, the two front and rear left wheels WFL, WFL are connected to one of the two outlet ports.
RL Corresponding air supply line 20 is provided on the other side, front and rear right wheels W
The air supply pipes 20 corresponding to FR and WRR are respectively connected. One of the two solenoid valves described above corresponds to the left and right outlet ports. Each air supply valve 22
When the two solenoid valves are both in the non-actuated position, the inlet port is closed to block the inflow of air pressure from the air supply line 24, and the two outlet ports and the exhaust port are simultaneously connected. The inside of each air supply conduit 20 is opened to the atmosphere. When the two solenoid valves of each air supply valve 22 can switch their respective positions in response to an operation signal from the ECU 28,
Each air supply valve 22 establishes communication between its inlet port and two outlet ports, and closes the exhaust port. This allows
Air pressure is supplied from the air tank 6 to the air-over-hydraulic booster 4 via the air supply lines 24 and 20 and the air pressure line 8, and the wheel brake is operated similarly to the service brake circuit. At this time, the ECU 28 operates only the solenoid valve corresponding to either the left or right wheel of the two solenoid valves of each air supply valve 22, so that only the air supply pipeline 20 corresponding to the one wheel is operated. Pneumatic pressure can be output. That is, the air pressure can be independently supplied from each air supply valve 22 to the air over hydraulic booster 4 corresponding to each of the four wheels. Therefore, in the automatic brake circuit, separately from the braking operation by the driver, that is, even if the brake valve 18 is not operated via the brake pedal 26, the braking force is individually generated for each wheel WFL, WFR, WRL, WRR. Can be made.

The pressure control valve 10 is composed of a valve unit containing two types of solenoid valves, and its schematic construction is shown in FIG.
Is shown in. As shown in the figure, the pressure control valve 10 has three ports, an inlet port, an outlet port, and an exhaust port. Further, an electromagnetic opening / closing type holding valve 10a and an electromagnetic direction switching type exhaust valve 10b are provided therein, and each solenoid is connected to the ECU 28. It should be noted that in FIG. 1, for convenience of drawing, the connection between the ECU 28 and the pressure control valve 10 is also shown by only one signal line.

The pressure control valve 10 is normally operated, that is, when the two solenoids are not energized, as shown in FIG.
Is in the open position, and the exhaust valve 10b is in the non-actuated position. In this state, the pressure control valve 10 establishes communication between its inlet port and outlet port and opens the pneumatic line 8. There is. Therefore, if the air supply valve 22 is opened, the air tank 6
From this, air pressure can be supplied, that is, air can be supplied to the air over hydraulic booster 4.

On the other hand, during this air supply, if only the holding valve 10a is operated, the inlet port of the pressure control valve 10 is closed and further air supply to the air over hydraulic booster 4 is cut off. However, the air pressure already supplied is maintained at that pressure. When the ECU 28 energizes the solenoid of the exhaust valve 10b in addition to the holding valve 10a, the exhaust valve 10b is also switched to the operating position. In this state, the outlet port of the pressure control valve 10 and the exhaust port are in communication. As a result, the compressed air supplied to the air over hydraulic booster 4 is discharged from the outlet port of the pressure control valve 10 through the exhaust port, that is, to the atmosphere.

Therefore, in the automatic brake circuit, the air supply valve 2
By controlling the switching operation of the pressure control valve 10 while switching 2 to supply the air pressure to the air over hydraulic booster 4, inside the air over hydraulic booster 4 separately from the brake operation by the driver. The raised hydraulic pressure, that is, the braking pressure supplied to each wheel cylinder 2 can be adjusted. The air supply valves 22 and the pressure control valve 10 described above form a braking force adjusting means.

By the operation of such an automatic brake circuit, the adjustment operation of the braking pressure supplied to each wheel cylinder 2 can be controlled by the ECU 28. ECU
28 is a storage circuit, a signal processing circuit, an arithmetic circuit,
A judgment circuit, a control circuit, a command circuit, etc. are provided. The operation control of the automatic brake circuit by the ECU 28 is performed by comprehensively determining the running state, the motion state, and the like of the vehicle 1. Therefore, sensor signals from various sensors are input to the ECU 28 in order to detect the motion state and the traveling state of the vehicle 1 during traveling. Among these sensors, a sensor for detecting a motion state includes a longitudinal acceleration sensor 32 for detecting longitudinal acceleration applied to the vehicle body and a lateral acceleration sensor 3 for detecting lateral acceleration.
4 and a yaw rate sensor 36 for detecting the yaw rate acting on the vehicle body. Further, the sensor for detecting the traveling state of the vehicle based on the driving operation of the driver includes a wheel speed sensor 30 for detecting the rotation speed of each wheel WFL, WFR, WRL, WRR, and the depression amount of the brake pedal 26, that is, ,
Pedal stroke sensor 3 for detecting pedal stroke
8 and a steering wheel angle sensor 42 for detecting the rotation angle of the steering wheel 40.

A brake air pressure sensor 44 for detecting the air pressure supplied to the air over hydraulic booster 4, that is, the actual braking air pressure is installed in the pneumatic pressure line 8. The sensor signal from 44 is also input to the ECU 28. In addition, an electronic governor controller 48 that directly outputs a command signal to the electronic governor 46 that controls the fuel injection amount is also electrically connected to the ECU 28.

As described above, the vehicle behavior control system of this embodiment comprises the automatic brake circuit described above, the ECU 28 for controlling the automatic brake circuit, various electronic devices connected to the automatic brake circuit, and various valves. There is. As described above, this vehicle behavior control device automatically stabilizes the behavior of the vehicle 1 during turning, and therefore, in actuality, the switching operation of the pressure control valve 10 and the air supply valve 22 is controlled respectively. By doing so, the braking pressure supplied to each wheel cylinder 2 is controlled, and as a result, the braking force generated on each wheel WFL, WFR, WRL, WRR is controlled respectively.

Referring to FIG. 3, the control concept of the vehicle behavior control device is shown. The outline of this control function is as follows.
After the sensor signals from various sensors (block 50) are filtered by the filter 52, the sensor signals are read into the arithmetic circuits 54 to 60, and the arithmetic circuits respectively execute the arithmetic processing. Then, the control circuit 64 determines a target control amount for automatic braking based on the calculation result and the sensor signal. In the command circuit 68, a final command signal is formed based on these target control amounts, and the command signal is output toward the controlled object 70. Here, what is directly controlled is the pressure control valve 10 and the air supply valve 22 as described above, and as a result, the braking air pressure supplied to the air over hydraulic booster 4 is controlled. .

In the vehicle behavior control apparatus of this embodiment, the target yaw rate of the vehicle is calculated as the target motion state of the vehicle as shown in the arithmetic circuit 58, and the control circuit 64 is also used.
Then, the target control amount for controlling the yaw moment of the vehicle is determined so that the detected actual motion state of the vehicle, that is, the actual yaw rate matches the target yaw rate. Therefore, as a result of controlling the braking air pressure as described above, the actual vehicle motion state (block 72) is controlled by the vehicle behavior control device. The braking air pressure and the motion state of the vehicle, which are the output results of the control, that is, the actual yaw rate, are respectively detected by the brake air pressure sensor 44 and the yaw rate sensor 36, and are fed back to the control system through the above-described filter processing. It Also,
The basic control cycle of the above control system is 8 ms.

Since yaw moment control is a known technique, the yaw moment control will be briefly described here. The yaw moment control is, for example, a diagonal braking force between front and rear diagonal wheels (left front wheel WFL and right rear wheel WRR when turning right, front right wheel WFL and left rear wheel WRL when turning left). By giving the difference, a turning yaw moment in the turning direction or a restoring yaw moment in the reverse direction of the turning is generated in the vehicle, whereby the actual yaw movement of the vehicle is made to coincide with the target yaw movement. Attitude control technology. The wheels to be controlled are not limited to the front and rear diagonal wheels, and may be the left front wheel WFL and the right front wheel WFR, or the left rear wheel WRL and the right rear wheel WRR.

Therefore, it is understood that such yaw moment control can be realized by controlling the above automatic brake circuit. When the yaw moment control is started and the vehicle returns to the steady turning state, the turning motion of the vehicle is autonomously stabilized, and the yaw moment control is ended there.

On the other hand, the yaw moment control is a control for correcting the turning motion of the vehicle, which tends to be unstable, in such a direction as to be stabilized, and more specifically, a control for matching the detected actual yaw rate with the target yaw rate. . Therefore, even if the deviation of these yaw rates becomes small, the yaw moment control may still function effectively. Therefore, if the ending condition of the yaw moment control is simply set based on the yaw rate deviation, there is a possibility that the control may be ended in the middle, although the yaw moment control is actually still functioning.

Referring now to FIG. 4, there is shown a main control routine for vehicle behavior control executed by the ECU 28, which shows a control procedure including processes for starting and ending the yaw moment control. Has been done. The control routine of FIG. 4 and the control block diagram of FIG. 3 will be described below. First, in step S10, various arithmetic processes are executed. These arithmetic processes are performed by the arithmetic circuit 54 shown in FIG.
At 56. First, in the arithmetic circuit 56, a more detailed traveling state of the vehicle 1 is calculated. That is, here, various variables such as the vehicle body speed V, the slip ratio S of each wheel, and the center-of-gravity slip angular velocity dβ are calculated from the wheel speed VW of each wheel, the longitudinal acceleration GX, the lateral acceleration GY, the actual yaw rate γ, and the like.

On the other hand, in the arithmetic circuit 54, the steering wheel angular velocity VTh is calculated from the steering wheel angle Th obtained from the detection value of the steering wheel angle sensor 38. When the above arithmetic processing is completed, the process proceeds to step S12. In step S12, the target yaw rate, which is the target motion state of the vehicle, is calculated. This calculation is performed by the arithmetic circuit 58 of FIG. 3, and here, the vehicle speed V and the steering wheel angle Th are first read.
Then, from the formula derived from the linear two-wheel model, the vehicle speed V
And the target yaw rate γt is obtained based on the steering angle δ of the front wheels obtained from the steering wheel angle Th.

Specifically, the target yaw rate γt is calculated from the following equation (1). γt = (V / (1 + A · V ² ) · (δ / L)) (1) where A: Stability factor L: Wheelbase [m] When the target yaw rate of the vehicle is calculated in this way, Then, the process proceeds to step S14.

In step S14, it is determined whether or not yaw moment control needs to be executed. More specifically, this determination is performed by the arithmetic circuit 60. Here, the deviation between the target yaw rate γt and the actual yaw rate γ and a reference value for determining the start condition of the yaw moment control, that is, a threshold value are compared, and the yaw rate is compared. When the deviation exceeds the threshold value, it is determined that the yaw moment control needs to be executed. On the other hand, if the yaw rate deviation is less than or equal to the threshold value, the yaw moment control is not executed.

In the arithmetic circuit 60, the required yaw moment Md to be applied to the vehicle 1 is obtained from the yaw rate deviation. Further, whether the required yaw moment Md is positive or negative is determined depending on whether the yaw rate deviation at this time is positive or negative. If the required yaw moment Md has a positive value, it can be said that the vehicle has an understeer tendency, and the required yaw moment Md is A negative value means oversteering. Therefore, the above-mentioned thresholds are also set in the positive and negative directions, respectively.

If it is not determined by the arithmetic circuit 60 that yaw moment control needs to be executed, step S14 is executed.
The result of the determination is false (No), and the routine of this time is ended without executing the yaw moment control. As described above, the yaw moment control is not started by operating the vehicle behavior control device while the yaw rate deviation does not exceed the threshold value.

On the other hand, if the yaw rate deviation exceeds the threshold value and it is determined that the arithmetic circuit 60 needs to execute the yaw moment control, the determination result in step S14 becomes true (Yes). In this case, Next in step S16
Proceed to. In step S16, the vehicle behavior control device is operated and yaw moment control is executed. Actually, as described above, the braking air pressure of the wheels to be controlled is controlled through the processing from the control circuit 64 to the controlled object 70, and the braking force difference is given between these wheels, so that the yaw moment of the vehicle 1 is increased. Control is performed.

Referring now to FIG. 5, a block diagram of the yaw moment control system at this time is shown in detail. As shown in the figure, the target yaw rate γt input to this control system is transmitted to each element of the control system and its format is sequentially converted. Then, in this control system, a closed loop is formed in which the finally output actual yaw rate γ is fed back. Hereinafter, the procedure for executing the yaw moment control will be described with reference to FIG.

As the processing in the arithmetic circuit 60, as described above, first, the subtraction unit 74 obtains the deviation between the input and the output, that is, the yaw rate deviation. Then, the required yaw moment Md is obtained by multiplying the yaw rate deviation by the gain 76. Next, the control circuit 64 obtains the target control amount for applying the braking force difference between the control target wheels from the required yaw moment Md, that is, the increase / decrease amount dP of the braking air pressure for the control target wheels.

Specifically, the increase / decrease amount dP of the braking air pressure is
The braking air pressure increase / decrease amounts dPf, dPr of the front and rear wheels are calculated for the front and rear wheels, respectively, and are calculated from the following equations (2.1), (2.2) programmed in the main controller 78. dPf = Md / (Bf · Tf) (2.1) dPr = Md / (Br · Tr) (2.2) B: Brake coefficient (front wheel: Bf, rear wheel Br) [kgf / kgf / cm
² ] T: Tread (front wheel: Tf, rear wheel: Tr) [m] can be obtained respectively.

Here, the sign of the increase / decrease amount dPf, dPr of the braking air pressure output from the main controller as the target control amount is positive (+) and negative (-) on the other.
That is, if the braking air pressure of one of the front and rear wheels to be controlled is increased, the other wheel is depressurized. As a result, the braking air pressure difference | dPf | + | d between the wheels to be controlled
A braking force difference generated by Pr | = dP is applied.

When the above process is completed, the control circuit 64 outputs the target control amount, the braking air pressure increase / decrease amount dP, to the command circuit 68. In the command circuit 68, command signals for the air supply valves 22 and the pressure control valve 10 are formed. First, the braking air pressure increase / decrease amount dP is added by the adder 80 to the braking air pressure Po of the non-controlled wheel to determine the target braking air pressure Pt. At this time, if the sign of the increase / decrease amount dP of the braking air pressure is positive, the target braking air pressure Pt = Po + dP
If the sign of the increase / decrease amount dP is negative, Pt =
Po-dP is given respectively.

In the next subtracting section 82, the target braking air pressure Pt
The deviation Per between the control target wheel actual braking air pressure P and the actual braking air pressure P is calculated. At this time, the actual braking air pressure P can be obtained from the detection value of the brake air pressure sensor 44. The sensor signal is also subjected to the filter processing by the filter 52 described above, that is, the filter processing by the low-pass filter 84.

After this, the deviation Per is a dead zone (not shown).
With this, it is possible to avoid noise that is included in the signal of the brake air pressure sensor 44, and a hypersensitive response to a slight change in the actual braking air pressure P. Therefore, a slight variation of the deviation Per in the dead zone region is ignored. The dead zone thresholds are, for example, 0.1 kgf /
It is set to cm ² .

The command circuit 68 outputs a switching signal for controlling the operation of the solenoid valve in the air supply valve 22 corresponding to each wheel to be controlled. As a result, air pressure is output from the air tank 6 toward the air over hydraulic booster 4.
Further, the command circuit 68 uses the two-variable map 86 in which the deviation Per and the actual braking air pressure P are variables, and the time for each of the compressed air supply mode, exhaust mode, and holding mode, that is,
The pulse width for energizing the solenoid of the pressure control valve 10 is obtained. The two-variable map 86 is prepared in advance and stored in a storage circuit not shown in FIG.

Here, the pressure control valve 10 can be driven in units of 1 ms, and its pulse width is set, for example, every 20 ms cycle. Therefore, the command circuit 68 outputs a rectangular pulse control signal Sp as shown in FIG. 6 to the pressure control valve 10. When the switching signal and the control signal Sp are output from the command circuit 68, the air supply valve 22 and the pressure control valve 10 corresponding to each wheel to be controlled are operated based on these signals. As a result, the compressed air, that is, the braking air pressure is supplied to the air over hydraulic booster 4 corresponding to the wheel to be controlled as described above. The braking air pressure at this time is detected by the brake air pressure sensor 44, passes through the low-pass filter 84, and then the actual braking air pressure P.
Is fed back to the subtraction unit 82 and the two-variable map 86 described above. Here, from the command circuit 68, the air supply valve 22
Focusing on the control system of the braking air pressure up to the pressure control valve 10, an output feedback loop is also formed in the pressure control system.

The control modes described above, that is, the compressed air supply, retention, and exhaust modes will be described. The control modes are selected by switching the supply valves 22 and the pressure control valve 10. Be seen. That is, by switching the operation of these valves, compressed air can be supplied to or exhausted from the air over hydraulic booster 4, and the braking air pressure at that time can be maintained. Further, the actual braking air pressure can be finely controlled by performing feedback control on the switching of these control modes.

[0045]

[Table 1]

Table 1 shows the relationship between the above-mentioned control modes and the operating states of the valves corresponding to the wheels to be controlled. In addition, ON or OFF in Table 1 represents energization or de-energization of the solenoid of the valve. As shown in Table 2, when the vehicle behavior control device is not controlled, that is, when the vehicle behavior control device is not operated, the operating state of any valve is OFF. In this case, only the braking operation by the driver, that is, the braking by the service brake is performed.

On the other hand, when the behavior control device of the vehicle is operated, one solenoid valve corresponding to each control target wheel in the air supply valve 22 is turned on, that is, switched to the operating position.
During operation of the vehicle behavior control device, the holding valve 10a and the exhaust valve 10b are turned on or off according to each control mode.
Switched to F. More specifically, first, in the air supply mode of the braking air pressure, both the holding valve 10a and the exhaust valve 10b are in one cycle (20 ms) for the air supply time obtained from the above-mentioned two variable map 80 from the start thereof. It is kept off, after which the rest of the period is switched to the hold mode, only the hold valve 10a is turned on and the exhaust valve 10b is kept off. Therefore, in the air supply mode, the compressed air from the aforementioned air tank 6 is supplied to the air over hydraulic booster 4, and the braking air pressure in the air over hydraulic booster 4 rises.

On the other hand, in the exhaust mode, both the holding valve 10a and the exhaust valve 10b are turned on for the exhaust time determined by the two-variable map 86 from the start of one cycle, and the remaining time of the cycle is the same. Switch to hold mode. Therefore, in this exhaust mode, the compressed air in the air over hydraulic booster 4 is exhausted, and the braking air pressure is reduced.

As a result of controlling the braking air pressure of each wheel to be controlled as described above, the hydraulic pressure raised by the air over hydraulic booster 4 is adjusted. Then, a braking force difference dF is generated between the wheels to be controlled due to the operation of the wheel brake (block 88). Then, a turning yaw moment or a restoring yaw moment M equal to the required yaw moment Md is generated in the vehicle body (block 90) due to the difference in inertial force dF between the front and rear diagonal wheels that are control target wheels. As a result, the actual yaw rate of the vehicle 1 during turning is brought closer to the target yaw rate.

The yaw moment control as described above is continuously executed until the end condition is satisfied. That is, as shown in the control routine of FIG. 4, it is determined whether or not the yaw moment is ended in step S18, and the determination result in step S18 is false, that is,
As long as the end condition of yaw moment control is not satisfied,
The procedure from step S10 to step S16 described above is repeatedly executed.

On the other hand, if the determination result in step S18 is true, that is, the condition for ending the yaw moment control is satisfied, the process proceeds to step S20, and the yaw moment control is ended. Hereinafter, the judgment of the end of the yaw moment control in step S18 will be described. As is clear from FIG. 5, the control amount of the wheel to be controlled for the wheel brake (block 88), that is,
The braking air pressure P depends on the braking air pressure increase / decrease amount dP which is the target control amount output from the main controller 78.
Therefore, the magnitude of the yaw moment finally exerted on the vehicle body (block 90) also depends on the braking air pressure increase / decrease amount dP output from the main controller 78. In other words, if the target control amount is large, the yaw moment control exerts its function to a great extent, and it can be said that the motion state of the vehicle 1 is given a positive correction momentum. In this case, the yaw moment control cannot be ended even if the yaw rate deviation becomes small.

On the other hand, if the target control amount is below a certain value and the state continues for a certain time or longer,
The contribution of the yaw moment control to the motion state of the vehicle 1 is already low. In this case, it can be said that the yaw moment control may be terminated. Therefore, step S18
Then, it is determined that the yaw moment control is terminated when both the increase and decrease amounts dPf and dPr of the braking air pressure are equal to or lower than the reference air pressure that determines the termination condition and the state continues for the reference time or longer. In addition, the reference air pressure in this case is set to a magnitude that hardly affects the motion state of the vehicle due to the braking force difference generated below the reference air pressure. Further, the above-mentioned reference time is sufficient to prevent the yaw moment control from being terminated when the wheels to be controlled are switched between the left and right by changing the turning direction, such as when turning the steering wheel. It needs to be set at a time that can be done. In addition,
In addition to the above termination conditions, as another termination condition, for example, the yaw moment control is also terminated when the vehicle speed becomes a low speed equal to or lower than the reference vehicle speed during control. This reference vehicle speed is set in a low speed range where it is not necessary to execute the yaw moment control.

The control circuit 64 determines whether or not the control is completed. That is, in the control circuit 64, when the output values of the braking air pressure increase / decrease amounts dPf and dPr, which are the target control amounts, are equal to or less than the reference air pressure and the reference time elapses in the same state, or the vehicle speed V is equal to or less than the reference vehicle speed. When, the yaw moment control is determined to be terminated. In this case, the determination result of step S18 becomes true, and the process proceeds to step S20.

In step S20, the end processing of the yaw moment control is executed. First, in the control circuit 64, the calculation in the main controller 78 is stopped. And E
In the CU 28, a control end processing routine that is set in addition to the main control routine is executed, and the yaw moment control, that is, the operation of the vehicle behavior control device is completely stopped.

As described above, according to the vehicle behavior control device of the above-described embodiment, it is accurately determined that the effect of the yaw moment control function on the motion state of the vehicle is reduced, and the operation of the automatic brake is ended. Can be made. Therefore, when the vehicle behavior is stable due to the effect of the yaw moment control, the braking force control for vehicle behavior control is not stopped, and it is possible to easily set a highly safe control termination condition. You can

Moreover, feedback control is performed by detecting the actual braking air pressure, and appropriate braking air pressure is generated at each wheel to be controlled based on the braking air pressure increase / decrease amounts dPf and dPr output from the control circuit. Since it is constantly monitored whether or not the braking force difference is present, there is little error in the braking force difference applied between these wheels, and it is possible to ensure high reliability in determining the end of the yaw moment control. Further, by feedback controlling the braking air pressure in this way, it is possible to eliminate the response delay in the air system of the air over hydraulic brake, so it is very useful for vehicles such as trucks and buses that use air pressure for the brake system. Will be suitable.

The present invention is not limited to the above embodiments. For example, the position at which the braking pressure is detected is not limited to the braking air pressure on the pneumatic line 8, and may be the position at which the hydraulic pressure in the hydraulic line 3 is detected. In this case, the pressure feedback system in the command circuit 68 requires a proportional gain for converting the hydraulic pressure into pneumatic pressure. Further, the brake system of the vehicle 1 is not limited to the air over hydraulic brake, and may be a full air brake. In this case, all hydraulic lines from the air over hydraulic booster 4 are replaced with pneumatic lines, and the wheel brakes are driven by the brake chamber.

Although the turning motion control of the vehicle by the yaw rate feedback method is shown in FIG. 5 as an example, the input set here, that is, the target motion state is not limited to the target yaw rate of the vehicle, and other May be the lateral acceleration of the vehicle during turning.
In this case, the target lateral acceleration of the vehicle is set to be equal to or less than the lateral acceleration that does not cause spin, drift out, rollover, or the like due to the vehicle receiving a turning lateral force. Then, the target control amount for automatic braking is set as a braking air pressure that generates a braking force that limits the lateral acceleration of the vehicle to the target lateral acceleration or less.

In addition, the behavior control device for a vehicle is not limited to the rear single-axle type vehicle of the embodiment, and can be applied to, for example, a rear double-axle type vehicle. In this case, the hydraulic lines 3 connected to the wheel cylinders 2 of the left and right rear wheels WRL and WRR are branched, and the branched hydraulic lines are connected to the wheel cylinders of the rear left and right rear wheels. The braking force control of the embodiment is likewise possible. However, when the amount of increase / decrease in the braking air pressure is determined by the increase in the braking force of the rear wheels, the value of the rear wheel braking coefficient Br is properly set in the above equations (2.1) and (2.2). Need to

[0060]

As described above, according to the vehicle behavior control device of the first aspect, the braking force difference due to the braking force control is eliminated when the vehicle autonomously returns to the stable turning motion. The times are almost the same, and the stable turning behavior of the vehicle is not impaired after the operation of the behavior control device of the vehicle is stopped. In addition, the control end condition of the vehicle behavior control device can be easily set without providing a special control end determination circuit. Therefore, from the start to the end of the turning control, it is possible to ensure a high degree of reliability in stabilizing the turning behavior of the vehicle by the vehicle behavior control device.

According to the behavior control device for a vehicle of claim 2,
The response delay to the control command based on the target control amount can be compensated to reliably apply the braking force difference, so there is no difference between the control end condition and the actual vehicle behavior, and the turning control safety Can be further improved.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a configuration of a brake system of a vehicle 1.

FIG. 2 is a diagram showing a detailed configuration of a pressure control valve 10.

FIG. 3 is a block diagram showing a control procedure of the vehicle behavior control device of the embodiment.

FIG. 4 is a flowchart showing a main control routine of a vehicle behavior control device.

5 is a block diagram showing a yaw rate feedback loop and a pressure feedback loop in a yaw moment control system of the ECU 28. FIG.

FIG. 6 is a diagram showing a pulse signal output from a command circuit 68.

[Explanation of symbols] 2 wheel cylinder 3 hydraulic lines 4 Air over hydraulic booster 6 air tanks 8 pneumatic lines 10 Pressure control valve 20 Air supply line 22 Air supply valve 24 Air supply line 28 ECU (control means) 30 wheel speed sensor 36 Yaw rate sensor 42 Handle angle sensor 44 Brake air pressure sensor 56 arithmetic circuit 60 arithmetic circuit 64 control circuit 68 Command circuit 78 Main controller

Continuation of front page (56) Reference JP-A-5-162629 (JP, A) JP-A-8-85430 (JP, A) JP-A-8-332932 (JP, A) JP-A-8-310361 (JP , A) JP 62-251268 (JP, A) JP 8-183438 (JP, A) JP 4-334650 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB) (Name) B60T 8/00 B60T 8/32-8/96

Claims (2)

(57) [Claims] 1. A braking force adjusting means that operates independently of a driver's braking operation and that is capable of adjusting a braking force that acts on a predetermined wheel, and traveling that detects and outputs a traveling state of a vehicle. State detection means, actual movement state detection means for detecting and outputting the actual movement state of the vehicle, and setting a target movement state of the vehicle based on the traveling state, and setting the actual movement state when the vehicle turns to the target movement state. the target control amount for imparting braking force difference between the reference wheel to match the by calculating a decrease amount, and a control means for controlling operation of the braking force adjusting means in accordance with the target control amount, the The vehicle behavior control apparatus, wherein the control means terminates the control when the state in which the target control amount is equal to or less than a predetermined value continues for a predetermined time. 2. An actual braking pressure detecting means for detecting and outputting an actual braking pressure acting on the predetermined wheel, wherein the control means sets the actual braking pressure to a target braking pressure determined based on the target control amount. The vehicle behavior control device according to claim 1, wherein feedback control is performed so as to make the two coincide with each other.