JP3425727B2 - Automatic braking system for vehicles - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic brake device for a vehicle, which appropriately controls the braking force of wheels when the vehicle turns to stabilize the turning behavior.

[0002]

Related Background Art A turning control device for automatically operating a brake to stabilize the turning behavior of a vehicle is, for example,
JP-A-3-276852 and JP-A-3-4236.
No. 0 publication. In the former control device, when the actual yaw rate of the vehicle lags behind the target yaw rate during turning of the vehicle, the braking force is applied to the turning inner wheel so that the actual yaw rate follows the target yaw rate.

On the other hand, in the latter control device, when the vehicle speed exceeds the grip limit vehicle speed of the tire at the time of turning, the inner wheel and the outer wheel of the turning are braked to recover the grip of the tire and prevent spin and drift out. ing.

[0004]

The former control device is effective in that the yaw motion of the vehicle can be positively controlled to compensate for the response delay of the vehicle to the driver's operation of the steering wheel. However, since the vehicle speed range in which the control is executed is based on the vehicle speed range in which the tire has an effective grip, the control should no longer be effective in the region where the grip limit vehicle speed of the tire is exceeded during turning. It is difficult.

On the other hand, the latter control device is effective as a means for restoring the grip of the tire by automatic deceleration and ensuring the steering operation of the driver, but with this control device, the yaw motion during turning is positive. Cannot be controlled. The present invention has been made based on the above-mentioned circumstances, and an object thereof is to positively control the yaw motion while stabilizing the vehicle turning behavior from beginning to end while limiting the vehicle speed to the limit vehicle speed or less during turning. An object of the present invention is to provide an automatic brake device for a vehicle, which can be realized.

[0006]

In order to achieve the above object, an automatic brake device for a vehicle according to claim 1 is provided on each wheel of the vehicle and receives a brake pressure to generate a braking force on the wheel. and the wheel brakes, independent of the driver's brake operation toward the wheel brake of each car wheel fluid pressure supplied to the fluid pressure supply means capable up braking pressure in the wheel brakes, at each vehicle wheel A braking pressure control unit that controls the braking pressure of the wheel brake according to the target control amount, and a setting unit that sets the target control amount are provided.
The setting means applies a braking force difference between predetermined wheels during turning of the vehicle to match the actual yaw motion of the vehicle with the target motion state.
A first arithmetic unit for determining a first control quantity for each wheel in order to execute the yawing motion control, the vehicle speed at the time of turning of the vehicle for each wheel in order to perform automatic deceleration control that limits below the limit vehicle speed 2 A second arithmetic unit for determining the controlled variable , and the first and second
Yo by adding the first and second control amount determined by the arithmetic unit
ー Perform at least one of motion control and automatic deceleration control
Determining a target control quantity for each wheel in order finally.

According to the vehicle automatic braking device of the first aspect, when the actual yaw motion of the vehicle does not match the target yaw motion during turning, or when the vehicle speed is about to exceed the limit vehicle speed, The braking force set for each wheel is automatically applied to each wheel, and yaw motion control or automatic deceleration control of the vehicle is performed. Furthermore, in both of these cases, that is, when the actual yaw motion of the vehicle does not match the target yaw motion and the vehicle speed is about to exceed the limit vehicle speed, yaw motion control and automatic deceleration control are performed simultaneously. By being
The vehicle speed is always limited to the limit vehicle speed or less, and a braking force difference is given between predetermined wheels, so that a turning yaw moment or a restoring yaw moment necessary for the vehicle is generated, and the turning behavior of the vehicle is stabilized.

According to another aspect of the present invention, there is provided an automatic brake device for a vehicle, comprising detection means for detecting the braking pressure in the wheel brake for each wheel, and the braking pressure control means is detected by the detection means for each wheel. The control is performed according to the deviation between the braking pressure and the target braking pressure corresponding to the target control amount. In this case, a feedback loop is formed in the braking pressure control system. Therefore, since the deviation between the target braking pressure and the actual braking pressure is taken into consideration in this control system, the control accurately reflects the degree of response of the actual braking pressure to the command from the braking pressure control means.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a vehicle automatic brake device of the present invention will be described below with reference to the drawings. First, Fig. 1
Referring to FIG. 1, there is schematically shown a configuration of a braking system in a vehicle 1 to which the automatic braking device of the 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 lines 2 on the front wheel side
0 is connected to one air supply valve 22, and the two air supply pipe lines 20 on the rear wheel side are connected to the other air supply valve 22.
That is, the downstream portion of each air supply conduit 24 is branched and connected to the relay valve 14 and the air supply valve 22 on the corresponding side. Therefore, the air supply line from the other inlet port of the double check valve 12 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 is a two-position electromagnetic directional control valve, and its solenoid is electrically connected to an electronic control unit, that is, the ECU 28.
More specifically, each air supply valve 22 has an inlet port, two outlet ports, and an exhaust port, the above-described air supply line 24 is provided at the inlet port, and the air supply line 20 is provided at each outlet port. Are connected respectively. When each air supply valve 22 is in the non-actuated position, it closes its inlet port to block the inflow of air pressure from the air supply line 24, and at the same time establishes communication between the two outlet ports and the exhaust port. Air supply line 2
The inside of 0 is open to the atmosphere. When the position of each air supply valve 22 is switched in response to the 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. As a result, the air pressure is supplied from the air tank 6 to the air over hydraulic booster 4 via the air supply lines 24, 20 and the air pressure line 8, and the wheel brake is operated similarly to the service brake circuit. Therefore, in the automatic brake circuit, in addition to 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 generated in each wheel WFL, WFR, WRL, WRR. You can

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. Note that, in FIG. 1, for convenience of drawing, the connection between the ECU 28 and the pressure control valve 10 is 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.

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 determination circuit, a control circuit, an instruction circuit, and the like are provided. The operation control of the automatic brake circuit by the ECU 28 is performed by comprehensively judging the motion state of the vehicle 1 and the driving operation of the driver. Therefore, sensor signals from various sensors are input to the ECU 28 in order to detect the motion state of the vehicle 1 during traveling and the driving operation of the driver. Among these sensors, the sensors for detecting the motion state include the wheels WFL, WFR, WRL, WRR.
A wheel speed sensor 30 that detects the rotational speed of the vehicle, a longitudinal acceleration sensor 32 that detects the longitudinal acceleration applied to the vehicle body, a lateral acceleration sensor 34 that also detects the lateral acceleration, and a yaw rate sensor 36 that detects the yaw rate acting on the vehicle body. . Further, the sensor for detecting the driving operation of the driver includes a pedal stroke sensor 38 for detecting the depression amount of the brake pedal 26, that is, a pedal stroke,
There is a steering wheel angle sensor 42 or the like 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 braking air pressure is installed in the pneumatic pressure line 8. The brake air pressure sensor 44 is provided. The sensor signal from is also input to the ECU 28.
In addition, to the electronic governor 46 that controls the fuel injection amount,
Electronic governor controller 48 that directly outputs a command signal
Is also electrically connected to the ECU 28.

As described above, the automatic brake device of this embodiment has the above-mentioned automatic brake circuit and E for controlling the automatic brake circuit.
CU28 and various electronic devices connected to it, and
It is composed of various valves. As described above, this automatic braking 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. Thus, 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.

Referring to FIG. 3, the control concept of the automatic braking device is shown. The outline of this control function is as follows.
After the sensor signals from the various sensors (block 50) are filtered by the filter 52, the sensor signals are read into the arithmetic circuits 54 to 62, and the arithmetic circuits respectively execute the arithmetic processing. Then, based on these calculation results and sensor signals, the yaw moment control circuit 64 and the automatic deceleration control circuit 66 respectively determine target control amounts for automatic braking. 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, the direct control target is the pressure control valve 10 as described above.
And the air supply valve 22, and as a result, the braking air pressure supplied to the air over hydraulic booster 4 is output. The braking air pressure as the output result is detected for each wheel by the brake air pressure sensor 44,
It is fed back to the control system through the above-mentioned filter processing. The basic control cycle of the above control system is 8 ms.

Here, since the yaw moment control and the automatic deceleration control are both known techniques, the yaw moment control and the automatic deceleration control will be briefly described here. The yaw moment control means, for example, diagonal wheels at the front and rear (when turning right, front left wheel WFL and right rear wheel WRR; when turning left, front right wheel WFL and left rear wheel WR).
By applying a braking force difference between L), 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, and thereby the actual yaw motion of the vehicle is targeted. It is a posture control technology that tries to match the yaw motion. 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,
It may be the left rear wheel WRL and the right rear wheel WRR.

Further, the automatic deceleration control means that the vehicle is automatically braked at the time of turning to decelerate the vehicle speed, and the lateral acceleration (lateral G) applied to the vehicle is limited to a lateral lateral limit which does not cause spin, drift out or rollover. This is a vehicle speed control technology that keeps the vehicle speed within the acceleration range, that is, limits the vehicle speed to the limit vehicle speed at that time or less. This control is effective when accelerating while turning, or when the driver further turns the steering wheel while turning.

Therefore, it is understood that both the yaw moment control and the automatic deceleration control can be realized by controlling the above automatic brake circuit. Referring to FIG.
An automatic brake control routine executed by the ECU 28 is shown, and the control routine and the block diagram of FIG. 3 will be described in detail below. First, step S1 in FIG.
At 0, it is determined whether or not the driver is operating the brake. This determination is performed by the driver's driving operation determination processing in the arithmetic circuit 54 shown in FIG. That is, the arithmetic circuit 54 determines whether or not the driver is performing a brake operation based on the sensor signal from the pedal stroke sensor 38, that is, the detected value of the pedal stroke B. When making this determination, the on / off state of the brake lamp switch is also taken into consideration.

Now, when the driver depresses the brake pedal 26 and the pedal stroke B exceeds 10 mm, for example, or in conjunction with the depression of the brake pedal 26,
If the brake lamp switch is turned on, it is determined that the driver is operating the brake, and step S1
The determination result at 0 is true (Yes). Step S10
As long as the determination result in step 1 is true, step S10 is repeatedly executed to give priority to the brake operation by the driver. However, when turning braking of the vehicle 1, that is, when the driver performs a brake operation during turning, a control routine different from this automatic brake control routine is executed. In this case, the automatic deceleration control is not executed, but the yaw moment control is executed separately. Therefore, when the driver does not perform the brake operation at the time of turning, either the automatic deceleration control or the yaw moment control is selectively executed, or both of them are integrally executed.

If the driver is not operating the brakes, or if the brakes are stopped, that is, if the pedal stroke is 10 mm or less and the brake lamp switch is off, the determination result in step S10 is The result is false (No), and the process proceeds to step S12. In step S12, it is determined whether or not the yaw moment control is necessary, that is, whether or not the yaw motion of the vehicle 1 needs to be actively controlled. The determination here is also the calculation circuit 54 to FIG.
This is performed by the arithmetic processing at 60, and the determination procedure will be described below.

In the arithmetic circuit 56, the motion state of the vehicle 1 is calculated. That is, here, various variables such as the vehicle body speed V, the slip rate 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 yaw rate γ, and the like. In the arithmetic circuit 54 described above, in addition to the determination in step S10, the steering wheel angle Th obtained from the detection value of the steering wheel angle sensor 38 is obtained.
From this, the steering wheel angular velocity VTh is calculated.

Next, the arithmetic circuit 58 calculates the target yaw rate of the vehicle. Here, the vehicle speed V and the steering wheel angle Th are first read. Then, from the equation derived from the linear two-wheel model, the target yaw rate γt is obtained based on the vehicle body speed V and 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.

Γt = (V / (1 + A · V ² ) · (δ / L)) where A: Stability factor L: Wheel base On the other hand, in the arithmetic circuit 60, the target yaw rate γt and the actual yaw rate γ are calculated. From the deviation, that is, the yaw rate deviation,
The required yaw moment Md to be applied to the vehicle 1 is obtained. Then, in the arithmetic circuit 60, the yaw rate deviation and the reference value for determining the start condition of the yaw moment control, that is,
The yaw rate deviation is compared with a threshold value, and when the yaw rate deviation exceeds this threshold value, it is determined that the yaw moment control needs to be executed, the determination result of step S12 becomes true, and the process proceeds to step S16. On the contrary, when the yaw rate deviation is equal to or less than the threshold value, it is determined that the yaw moment control need not be executed, the determination result of step S12 becomes false, and the process proceeds to step S14. The sign of the yaw rate deviation at this time determines whether the required yaw moment Md 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 if the required yaw moment Md has a negative value, it can be said that the vehicle has an oversteer tendency. Therefore, the above-mentioned thresholds are also set in the positive and negative directions, respectively.

In steps S14 and S16, it is determined whether or not the automatic deceleration control is required, that is, whether or not the vehicle speed needs to be automatically decelerated. This determination is also performed by the arithmetic processing in the arithmetic circuits 54, 56 and 62 of FIG. More specifically, the vehicle speed V is calculated by the arithmetic circuit 56.
After the calculation of
And the turning radius of the vehicle are estimated from the lateral acceleration GY, the road surface μ is estimated from the lateral acceleration GY and the longitudinal acceleration GX, and the lateral acceleration GY is limited to a limit lateral acceleration or less based on the turning radius and the road surface μ. A safe vehicle speed Vs is required. Then, the target deceleration GXt is calculated by multiplying the deviation between the safe vehicle speed Vs and the actual vehicle body speed V by the feedback gain. That is, the target deceleration GXt is calculated from the following equation. The target deceleration GXt is usually a negative acceleration.

GXt = Kp (Vs-V) where Kp: Feedback gain Then, in the arithmetic circuit 62, the target deceleration GXt is compared with the threshold value that determines the start condition of the automatic deceleration control, and the target deceleration GXt. Is above the threshold value, it is determined that the automatic deceleration control needs to be executed, and the determination results of steps S14 and S16 are true. On the contrary, when the target deceleration GXt is less than or equal to the threshold value, it is determined that it is not necessary to execute the automatic deceleration control, and the determination results of steps S14 and S16 are false.

If the determination result in step S14 is false, neither the yaw moment control nor the automatic deceleration control is executed, and the execution of this routine ends. As described above, the automatic braking device is not activated while it is determined that neither the yaw moment control nor the automatic deceleration control is necessary in a situation where the driver is not operating the brake.

On the other hand, even if the determination result of step S16 is false, since the determination result of step S12 is true, the process proceeds to step S18 and only the yaw moment control is executed. In step S18, the yaw moment control circuit 64 shown in FIG. 3 determines the target control amount for yaw moment control, that is, the target braking air pressure Pyt for each wheel.

Specifically, the target braking air pressure Pyt for each wheel is
Are calculated based on the required yaw moment Md, the front and rear brake coefficients, and the tread, respectively.
Although the yaw moment control during the braking of the brake pedal 26, that is, during braking is not executed in the routine shown in FIG. 4, in the yaw moment control during braking, the target for each wheel is The braking air pressure is set to a value obtained by increasing or decreasing the actual air pressure of the wheel by Pyt.

If the determination result in step S14 is true,
In step S20, only the automatic deceleration control is executed. In step S20, the automatic deceleration control circuit 66 of FIG.
At, the target control amount for the automatic deceleration control, that is, the target braking air pressure Pbt for each wheel is determined. In particular,
The target braking air pressure Pbt is obtained by multiplying the difference between the target deceleration GXt and the actual deceleration obtained by subtracting the cornering drag and the integral value of the difference by a feedback gain, and then adding these multiplication values. . The target braking air pressure Pbt of each wheel is common.

If the determination result in step S16 is false, the process proceeds to step S22, in which integrated control of yaw moment control and automatic deceleration control is executed. In step S22, the target braking air pressures Pyt and Pbt are respectively determined by the yaw moment control circuit 64 and the automatic deceleration control circuit 66 described above. Thus, in the ECU 28, the arithmetic circuits 54 to 6
After performing various calculations and determination processing in 2, the target control amount is determined by the yaw moment control circuit 64 and the automatic deceleration control circuit 66, respectively. Then, the target braking air pressures Pyt and Pbt determined for each wheel are finally converted into operation command signals to the air supply valve 22 and the pressure control valve 10 by the command circuit 68, and the corresponding air supply valve 22. And to the pressure control valve 10.

Referring to FIG. 5, the signal forming process in command circuit 68 is shown in more detail. The command circuit 6
8 can form respective command signals for each of the wheels WFL, WFR, WRL, WRR, and the signal forming processing procedure for one wheel will be described below. Figure 5
As shown in, first, the target braking air pressures Pyt and Pbt are added by the adder 72. The addition process here is
The meaning differs depending on which of the above-described steps S18, S20, S22 is executed. That is, step S
When step 18 is executed, only the target braking air pressure Pyt for the yaw moment control is output to the command circuit 68, and the target braking air pressure Pbt for the automatic deceleration control is not output. Therefore, in this case, the signal of the target braking air pressure Pyt simply passes through the adding section 72.

Similarly, if step S20 is executed, only the target braking air pressure Pbt for automatic deceleration control is output to the adding section 72. In this case as well, the adding section 72 also targets the target braking air pressure Pbt. The signal of simply passes through. On the other hand, if step S22 is executed, both target braking air pressures Pyt and Pbt are both output to the addition section 72. In this case, therefore, the addition section 72 actually adds the both. Become.

The value thus obtained is set as the final target control amount, that is, the final target braking air pressure Pft. In the next subtraction unit 74, the deviation Per between the final target braking air pressure Pft 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. It should be noted that this sensor signal has been subjected to the filter processing by the filter 52 described above, that is, the filter processing by the low-pass filter 76.

Thereafter, the deviation Per is passed through the dead zone 78, so that the noise contained in the signal of the brake air pressure sensor 44 and the hypersensitive response to the minute fluctuation of the actual braking air pressure P are avoided. Therefore, a slight variation of the deviation Per within the dead zone 78 is ignored. The threshold value of the dead zone 78 is, for example, 0.1 kgf in each of the positive and negative directions.
/ Cm ² is set.

The command circuit 68 outputs a switching signal for controlling the operation of the air supply valve 22 according to the magnitude of the deviation Per. In addition, the command circuit 68 controls the deviation Per and the actual braking air pressure P.
The time for each of the compressed air supply mode and the holding mode, that is, the pulse width for energizing the solenoid of the pressure control valve 10 is obtained from the two-variable map 80 in which each is a variable. The two-variable map 80 is prepared in advance and stored in a storage circuit (not shown).

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, each air supply valve 22 and the pressure control valve 10 are operated based on these signals. As a result, as described above, the air over hydraulic booster 4
The compressed air, that is, the braking air pressure is supplied toward. The braking air pressure at this time is measured by the brake air pressure sensor 4
4 and is passed through the low-pass filter 76 and then fed back as the actual braking air pressure P to the subtractor 74 and the two-variable map 80 described above. Thus, an output feedback loop is formed in the braking air pressure control system.

The respective modes described above, that is, the air supply mode, the holding mode, and the exhaust mode will be described below. These modes mean the operation modes of the air supply valves 22 and the pressure control valve 10. By switching the operation of
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 feedback controlling the switching of these operation modes.

[0046]

[Table 1]

Table 1 shows the relationship between the control mode of the automatic braking device and the operating mode of each valve.
In addition, ON or OFF in Table 1 represents energization or de-energization of the solenoid of the valve. As shown in Table 1, in the non-controlled state, that is, in the state where the automatic braking device is not operated, the operation mode of any valve is OFF. Therefore, 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 automatic brake control is started, the air supply valve 22 is switched to the operating position. Then, during operation of the automatic brake device, the pressure control valve 10, that is, the holding valve 10a and the exhaust valve 10b are switched to ON or OFF according to each control mode. More specifically, first, in the braking air pressure supply mode, one cycle (20 m
In s), the holding valve 10a and the exhaust valve 1 are operated for the air supply time calculated from the two-variable map 80 from the start.
0b are both kept off, and thereafter, the remaining time in the cycle is switched to the holding mode, only the holding 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 80 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 described above, the ECU 28 can control the braking air pressure for each wheel WFL, WFR, WRL, WRR through the above-described procedure and control the hydraulic pressure supplied to each wheel cylinder 2. That is, in the automatic brake device of this embodiment, the braking pressure supplied to the wheel brake of each wheel is a hydraulic pressure which is converted by the air over hydraulic booster 4 and is raised here. The braking air pressure for raising the hydraulic pressure can be supplied to each wheel from the air tank 6 independently of the driver's braking operation by switching the operation modes of the air supply valve 22 and the pressure control valve 10. And its pressure is also adjustable. Further, the ECU 28 controls the operation of the air supply valve 22 and the pressure control valve 10 to control the supply / discharge of the braking air pressure and the supplied pressure.

In other words, each wheel WFL, WFR, WRL,
It is nothing but the individual control of the braking force itself generated in WRR. The control of the braking force is executed for the purpose of the yaw moment control and the automatic deceleration control of the vehicle body described above. The braking force applied to the wheels and the resulting turning behavior of the vehicle 1 will be described.

7 and 8 show the operation of the automatic braking device and the turning behavior of the vehicle 1 during yaw moment control, respectively. Note that, as an example, a case of turning to the right will be described below. Referring to FIG. 7, the actual yaw movement of the vehicle 1 is delayed as indicated by the dashed arrow with respect to the target yaw movement direction indicated by the solid arrow, and this state is so-called understeer. In addition,
Such understeer recognition is calculated by the ECU 28.
It is as described above that it is determined. In this case, the braking force FXy is applied to the inner rear wheel, that is, the right rear wheel WRR when viewed in the turning direction. This additional braking force FXy is
It is applied to the target wheel WRR independently of the driver's brake operation. If the driver is operating the brake during turning, the braking force FXy
Is added, and if the driver has not performed any braking operation, the braking force FXy is simply applied to the right rear wheel WRR. However, in the automatic brake control routine shown in FIG. 4, since the yaw moment control is not executed when the driver is performing the braking operation, in this case, as shown in FIG. 7, the braking force FXy is applied to the right rear wheel WRR. Only given.

At this time, as viewed between the front and rear diagonal wheels WFL and WRR, no braking force is generated on the left front wheel WFL, and a braking force difference of FXy is applied between these diagonal wheels. Due to this braking force difference, a rightward yaw moment that assists the vehicle 1 in turning, that is, a turning yaw moment is generated. The magnitude of the braking force FXy at this time is determined by the right rear wheel W.
The magnitude of the braking force generated by the target braking air pressure Pyt of RR is equal to the magnitude of the turning yaw moment, and the magnitude of the required yaw moment Md obtained by the arithmetic circuit 60 is equal. On the other hand, FIG. 8 shows a so-called oversteer state in which the actual yaw motion is overshooting the target yaw motion. In this case, braking force FXy is applied to the left front wheel WFL, and a yaw moment in the reverse direction of turning, that is, a restored yaw moment is generated. The braking force FXy at this time is similarly generated by the target braking air pressure Pyt of the left front wheel WFL, and the magnitude of the restored yaw moment is also equal to the magnitude of the required yaw moment Md in the reverse direction.

By executing such yaw moment control, the vehicle 1 can be made to follow the turning line desired by the driver. FIG. 9 shows the operation of the automatic braking device and the turning behavior of the vehicle 1 during the automatic deceleration control. In this case, the braking force FXb that should generate the above-described target deceleration GXt is applied to the left and right front wheels WFL and WFR and the turning inner rear wheel, that is, the right rear wheel WRR. By executing this automatic deceleration control, the lateral acceleration GY can be suppressed below the above-described limit lateral acceleration.

The limit lateral acceleration in this case is taken into consideration not only the grip limit of the tire but also the lateral acceleration within a range in which a vehicle having a relatively high center of gravity such as a truck or a bus does not roll over. Therefore, in this automatic deceleration control, it is assumed that the friction coefficient between the road surface and the tire is relatively high. During the automatic deceleration control, a separate control signal is output from the ECU 28 to the electronic governor controller 48, and the electronic governor controller 48 determines the fuel injection amount based on the control amount of the automatic deceleration. As a result, the output of the engine is reduced simultaneously with the automatic deceleration control.

10 and 11 show the operation of the automatic brake device and the turning behavior of the vehicle 1 during the integrated control of the yaw moment control and the automatic deceleration control, respectively. Referring to FIG. 10, the vehicle 1 has a tendency to turn understeer. In this case, the required braking force FXb is applied to the left and right front wheels WFL, WFR and the right rear wheel WRR based on the control rule for automatic deceleration. As a result, the target deceleration GXt is applied to the vehicle 1.

The front and rear diagonal wheels, that is, the right front wheel WFR
A braking force difference is applied to the left rear wheel WRL based on the yaw moment control law. More specifically, for the left front wheel WFL, the braking force Fb is reduced in the direction of decreasing the braking force FXb for automatic deceleration.
Xy acts, and conversely, the braking force FXy acts on the right rear wheel WRR in the direction of increasing the braking force FXb for automatic deceleration. Therefore, a braking force difference is generated between the front and rear diagonal wheels and the left and right front wheels, and the required yaw moment Md in the turning direction shown in FIG. 10 is generated in the vehicle 1.

On the other hand, referring to FIG. 11, the vehicle 1
Has a tendency to turn oversteer. In this case, the braking force FXb is applied to each of the predetermined three wheels in the same manner as described above, and the target deceleration GXt is applied to the vehicle 1. A braking force difference is given to the front and rear diagonal wheels based on the yaw moment control law. In this case, the braking force FXy acts on the left front wheel WFL in the direction to increase the automatic deceleration braking force FXb, and the braking force FXy acts on the right rear wheel WRR in the direction to decrease the automatic deceleration braking force FXb. So in this case,
Due to the braking force difference between the front and rear diagonal wheels and between the left and right front wheels, the required yaw moment Md in the restoring direction is generated in the vehicle 1.

Incidentally, such integrated control of the yaw moment control and the automatic deceleration control by the ECU 28 can be realized by the addition processing in the command circuit 68 described above. That is, the target braking air pressure Pbt based on the automatic deceleration control law and the target braking air pressure Pyt based on the yaw moment control law are added by the adder 72 (see FIG. 5) described above, so that the left front wheel WFL The target braking air pressure Pft = (Pyt + Pbt) is given to each of the right rear wheel WRR and the right rear wheel WRR. At this time, if the turning yaw moment is required as shown in FIG. 10, the target braking air pressure Pyt1 takes a negative value, and conversely, the target braking air pressure Pyt4 takes a positive value. As a result, the braking force FXb of the left front wheel WFL is reduced, while the braking force FXb of the right rear wheel WRR is increased. Further, as shown in FIG. 11, when the restoring yaw moment is required, the signs of the target braking air pressures Pyt1 and Pyt4 are opposite to the above, and the braking force FXb of the left front wheel WFL is increased and the right rear wheel WRR is increased. The braking force FXb is reduced.

As described above, according to the above-described automatic braking device, the yaw moment control and the automatic deceleration control are not executed independently and separately from each other, and the yaw moment control and the automatic deceleration control are performed at the same time. Can be executed. That is, the yaw moment of the vehicle can be positively controlled while executing the automatic deceleration control during turning, and there is no control mode switching between the yaw moment control and the automatic deceleration control. There is no fear that the control mode of (1) is once shut off and the other control mode is started again, and the behavior of the vehicle suddenly changes when this mode is switched. Therefore, even when the vehicle tends to exceed the limit vehicle speed when turning, even if the vehicle tends to understeer or oversteer, it is possible to effectively eliminate the understeer or oversteer while keeping the vehicle speed below the limit vehicle speed.

Moreover, feedback control is performed by detecting the actual braking air pressure, and it is constantly monitored whether an appropriate braking force for control is generated, so that the reliability of the control system is further improved. Can be made. Further, the feedback control of the braking air pressure can eliminate the response delay in the air system of the air over hydraulic brake, which is very suitable for vehicles such as trucks and buses that use air pressure for the brake system.

The present invention is not limited to the above embodiments. For example, the position where the braking pressure is detected is not limited to the position on the pneumatic line 8 and may be the position where 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,
A full air brake is also acceptable. In this case, the hydraulic system from the air over hydraulic booster 4 is replaced by the pneumatic system, and the wheel brake is driven by the brake chamber.

The target wheels for the braking force control in the yaw moment control are not limited to the front and rear diagonal wheels, but may be the left and right front wheels or the left and right rear wheels as described above. Further, the target wheels of the automatic deceleration control are not limited to the three wheels of the left and right front wheels and the inner rear wheel in the turning direction, and may be all four wheels. In addition, the automatic brake device is not limited to the rear single-axle type vehicle, and may be applied to the rear double-axle type vehicle, for example. 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.

[0064]

As described above, according to the vehicle automatic brake device of the first aspect, the yaw motion of the vehicle is positively corrected while automatically limiting the vehicle speed to the limit vehicle speed or less during turning. Therefore, the turning behavior of the vehicle can be stabilized all the time. Moreover, even if the behavior of the vehicle suddenly changes during turning, one control is not abruptly interrupted, and a driving feeling that is comfortable to the driver can be obtained.

According to the vehicle automatic brake device of the second aspect, the rising delay of the braking pressure with respect to the control command can be compensated, and the braking pressure, that is, the braking force can be quickly and finely controlled. Therefore, the automatic deceleration control and the yaw motion control can be effectively performed with high reliability.

[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 automatic brake device of the embodiment.

FIG. 4 is a flowchart showing an automatic brake control routine.

5 is a block diagram showing a feedback loop in a control system of ECU 28. FIG.

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

FIG. 7 is a diagram showing the operation of the automatic braking device and the turning behavior of the vehicle 1 at the time of right turn understeer.

FIG. 8 is a diagram showing the operation of the automatic braking device and the turning behavior of the vehicle 1 at the time of overturning to the right.

FIG. 9 is a diagram showing the operation of the automatic brake device and the turning behavior of the vehicle 1 during automatic deceleration of a right turn.

FIG. 10 is a diagram showing the operation of the automatic braking device and the turning behavior of the vehicle 1 at the time of right turn understeer and automatic deceleration.

FIG. 11 is a diagram showing the operation of the automatic brake device and the turning behavior of the vehicle 1 at the time of right turn oversteer and automatic deceleration.

[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 64 Yaw moment control circuit (first calculation unit) 66 Automatic deceleration control circuit (second calculation unit)

─────────────────────────────────────────────────── --Continued from the front page (56) References JP-A-3-45453 (JP, A) JP-A-3-276855 (JP, A) JP-A-3-112754 (JP, A) JP-A-3- 70663 (JP, A) JP-A-3-276852 (JP, A) JP-A-3-42360 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) B60T 8/00-8 / 96 B60T 7/12-7/22

Claims (2)

(57) [Claims] 1. A provided in each wheel of the vehicle, a wheel brake for generating a braking force to the wheels supplied with brake pressure, independent of the driver's brake operation toward the wheel brakes of the vehicle wheel supplying fluid pressure, said fluid pressure supply means capable up braking pressure in the wheel brakes, the brake pressure control means for controlling in accordance with the target control amount of the braking pressure in the wheel brake in each car wheel, the target control and a setting means for setting an amount, the setting means, a yaw motion control for by applying a braking force difference between the predetermined wheel during turning of the vehicle to match the actual yaw motion of the vehicle to a desired motion state
A first arithmetic unit for determining a first control quantity for each wheel in order to execute the automatic deceleration that limits the speed below the limit vehicle speed when the vehicle turns
A second calculation unit that determines a second control amount for each wheel to execute control is provided , and the first and second control amounts determined by the first and second calculation units are added , The yaw motion control and the automatic reduction
Automatic braking device for a vehicle, characterized in that to make the final determination on the target control amount of each wheel for performing at least one fast control. 2. A detection means for detecting a braking pressure in the wheel brake for each wheel, wherein the braking pressure control means has the braking pressure detected by the detection means for each wheel and the target control. The automatic braking device for a vehicle according to claim 1, wherein the automatic braking device is controlled according to a deviation from a target braking pressure corresponding to the amount.