JP2007062423A - Braking control device for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accomplish feedback control of braking force effectively utilizing resistance force at braking on a road surface where the resistance force by wedge effect is generated in addition to braking force by friction such as gravel road. <P>SOLUTION: The braking force by the wedge effect that a gravel interposed in the wedge shape between a wheel and a road surface is bitten is generated in addition to the braking force by friction at braking on the gravel road. Addition deceleration Ge by the wedge effect is operated in an operation part 34 and is added to target deceleration tG to determine a target deceleration correction value Gc. Target braking torque Tbff for feed forward control for accomplishing tGc is determined in an operation part 35 and a braking torque feedback compensation amount ΔTbfb for eliminating deviation: ΔG=tGc-G (making it to tGc=G) of the target deceleration correction value tGc and a deceleration detection value G is determined. The final target total braking torque tTb obtained by adding Tbff and ΔTbfb is distributed to braking force of respective wheels at a distribution part 37. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a braking control device for a vehicle, and in particular, when a resistance force for decelerating the vehicle other than the deceleration force due to friction is generated between the wheel and the road surface during the control of the wheel braking force, the resistance force is effectively used. The present invention relates to a vehicle braking control device capable of performing efficient braking.

As a vehicle braking control device, for example, as described in Patent Document 1, based on a deceleration deviation between a target deceleration obtained from the braking operation state of the vehicle and an actual deceleration of the vehicle detected by a sensor, A device that feedback-controls the braking force of a wheel so that the deceleration becomes a target deceleration is known.
JP 2003-170823 A

  However, in the prior art described in Patent Document 1, since the braking force is feedback-controlled based on the deceleration deviation between the target deceleration and the actual deceleration detection value, the problem described below occurs. I confirmed.

That is, when braking is performed while traveling on a gravel road, a deep snow road, a muddy road, or the like, a resistance force that decelerates the vehicle is generated between the wheels and the road surface in addition to the normal deceleration force.
This resistance is caused by the tread pattern unevenness provided on the tire ground contact surface of the wheel, gravel, snow, and mud between the road surface, and dirt, sand, and snow are caused by wheel locking and slipping. It is caused by the so-called wedge effect that resists by scraping forward and creating a mountain, and it acts to decelerate the vehicle, and this force cooperates with the deceleration force due to friction between the wheels and the road surface to reduce the vehicle. Generate speed.

By the way, when the braking force is feedback controlled based on the deceleration deviation between the target deceleration and the actual deceleration detection value as in the past,
The detected deceleration value is large, including not only the deceleration due to friction but also the deceleration due to the wedge effect described above, and as a result, the deceleration deviation between the target deceleration and the detected deceleration value becomes smaller. The braking force that is feedback-controlled so as to eliminate the deviation is also reduced by an amount corresponding to the deceleration due to the wedge effect, and efficient braking force control that effectively uses the resistance force due to the wedge effect cannot be performed.

  By the way, in feedforward that uniquely determines the braking force according to the target deceleration, the actual deceleration detection value is not fed back, so the control due to the wedge effect is not considered, and the resistance force due to the wedge effect is effective. Since the braking force control is performed, the phenomenon as in the above feedback control, that is, the phenomenon that the braking force is not added with the amount corresponding to the deceleration due to the wedge effect does not occur.

  In the case of the conventional braking force control in which the braking force is not increased by the amount corresponding to the deceleration due to the wedge effect as described above, even if the driver increases the brake pedal to obtain a larger braking force, the road surface friction is increased. There arises a problem that only a braking force corresponding to the force can be obtained.

In solving this problem, it is conceivable to use the feedforward control as described above. However, this feedforward control is inferior to the most important disturbance resistance,
Preferably, feedback control based on a deceleration deviation between the target deceleration and the actual deceleration detected value as exemplified in Patent Document 1 is good.

The present invention follows the feedback control as usual from this viewpoint.
The present invention excludes the deceleration according to the resistance due to the wedge effect from the feedback system after the detected actual deceleration value including the deceleration according to the resistance due to the wedge effect exceeds the target deceleration. Until the deceleration due to friction reaches the target deceleration, the braking force is effectively controlled using the resistance force due to the wedge effect.
Accordingly, an object of the present invention is to propose a braking control device for a vehicle that can solve the above problem.

For this purpose, the braking control device for a vehicle according to the present invention is configured as described in claim 1.
First of all, to explain the premise braking device,
The wheel braking force is controlled so that the vehicle deceleration becomes the target deceleration according to the deceleration deviation between the target deceleration obtained from the braking operation state of the vehicle and the detected deceleration value of the vehicle. Is.

The present invention provides such a braking device,
During the control of the wheel braking force, when it is detected that a resistance force that decelerates the vehicle other than the deceleration force due to friction is generated between the wheel and the road surface, and when the deceleration detection value exceeds the target deceleration, It is configured to limit the vehicle deceleration to the target deceleration according to the deceleration deviation by the control of the wheel braking force.

For the same purpose, the vehicle braking control device according to the present invention, as described in claim 2, with respect to the braking device having the same preconditions as described above,
During the control of the wheel braking force, a resistance force generation detecting means for detecting that a resistance force for decelerating the vehicle other than the deceleration force due to friction is generated between the wheel and the road surface;
An excessive deceleration detection means for detecting that the deceleration detection value exceeds the target deceleration;
By these means, when the generation of the resistance force is detected and a large deceleration detection value exceeding the target deceleration is detected, the deceleration due to the resistance force is excluded instead of the control of the wheel braking force. And a braking force control law changing means for changing the braking force control law so as to switch to the braking force control.

According to the braking control device of claim 1,
Wheel braking force for controlling the wheel braking force so that the vehicle deceleration becomes the target deceleration according to the deceleration deviation between the target deceleration obtained from the vehicle braking operation state and the vehicle deceleration detection value During the control of the wheel, when it is detected that a resistance force other than the deceleration force due to friction between the wheels and the road surface is generated and the detected deceleration value exceeds the target deceleration value, the wheel braking force In order to limit the vehicle deceleration to the target deceleration according to the deceleration deviation by the control of
When the occurrence of the resistance force is detected and the detected deceleration value including the deceleration according to the resistance force exceeds the target deceleration, the deceleration according to the resistance force due to the wedge effect is excluded from the feedback system. From this time, it is possible to perform efficient braking force control that effectively utilizes the resistance force caused by the wedge effect.
Therefore, when the driver increases the brake pedal in order to obtain a larger braking force, in addition to the braking force corresponding to the road surface friction force, the braking force associated with the resistance force due to the wedge effect can be obtained. The conventional problem that only the braking force corresponding to the above can be obtained can be solved.

In the braking control device according to claim 2,
The resistance force generation detecting means detects that a resistance force for decelerating the vehicle other than the deceleration force due to friction is generated between the wheel and the road surface during the control of the wheel braking force, and
When the excessive deceleration detection means detects that the deceleration detection value exceeds the target deceleration,
In order for the braking force control law changing means to change the braking force control law so as to switch to the braking force control excluding the deceleration due to the resistance force instead of the wheel braking force control,
When the occurrence of the resistance force is detected and the detected deceleration value including the deceleration according to the resistance force exceeds the target deceleration, the deceleration according to the resistance force due to the wedge effect is excluded from the feedback system. From this time, it is possible to perform efficient braking force control that effectively utilizes the resistance force caused by the wedge effect.
Therefore, when the driver increases the brake pedal in order to obtain a larger braking force, in addition to the braking force corresponding to the road surface friction force, the braking force associated with the resistance force due to the wedge effect can be obtained. The conventional problem that only the braking force corresponding to the above can be obtained can be solved.

Hereinafter, embodiments of the present invention will be described in detail based on examples shown in the drawings.
FIG. 1 shows a hydraulic brake system including a braking control device according to an embodiment of the present invention. Reference numeral 1 denotes a brake pedal that is depressed in accordance with a vehicle deceleration requested by a driver.
When the unillustrated piston cup in the master cylinder 2 is pushed in by the depression force of the brake pedal 1, the master cylinder 2 applies the master cylinder hydraulic pressure Pm corresponding to the depression force of the brake pedal 1 to the two systems of front wheel brake hydraulic pressure piping 3 , 4 shall be output.

  Brake hydraulic piping 3 is connected to the left front wheel wheel cylinder 5FL, brake hydraulic piping 4 is connected to the right front wheel wheel cylinder 5FR, and the left and right front wheels related to these can be braked by the master cylinder hydraulic pressure Pm. In addition, the left and right rear wheels (wheel cylinders are indicated by 5RL and 5RR) are braked by brake hydraulic pressures Pwfl, Pwfr, Pwrl, and Pwrr electronically controlled by the configuration described later.

For this reason, the master cut valves 6FL and 6FR are inserted into the brake fluid pressure pipes 3 and 4 respectively, and the master cut valves 6FL and 6FR are normally opened but closed when turned on.
While the master cut valves 6FL and 6FR are closed due to ON, even if the master cylinder hydraulic pressure Pm is generated in the brake hydraulic pressure piping 3 and 4 upstream of these, the stroke of the brake pedal 1 does not occur, which makes it strange. Therefore, a stroke simulator 7 for generating a normal pedal stroke is provided connected to the master cylinder 2.

In order to be able to electronically control the brake fluid pressures Pwfl, Pwfr and Pwrl, Pwrr of the left and right front wheels and the left and right rear wheels, a pump 8 is provided which uses the brake fluid in the reservoir 2a of the master cylinder 2 as a working medium, The circuit 9 is connected to the reservoir 2a.
The pump 8 is driven by a motor 10 to discharge the brake fluid sucked from the reservoir 2a through the circuit 9 to the circuit 11, and accumulates the discharged brake fluid in the accumulator 12.
The internal pressure of the accumulator 12 is detected by the pressure switch 13 and sequence controlled.

Discharge circuit 11 is connected to left front wheel wheel cylinder 5FR by circuit 14FL, connected to right front wheel wheel cylinder 5FR by circuit 14FR, connected to left rear wheel wheel cylinder 5RL by circuit 14RL, and right rear wheel wheel cylinder by circuit 14RR. Connect to 5RR.
Then, the pressure increasing valve 15FL is inserted into the circuit 14FL, the pressure increasing valve 15FR is inserted into the circuit 14FR, the pressure increasing valve 15RL is inserted into the circuit 14RL, and the pressure increasing valve 15RR is inserted into the circuit 14RR.
Circuits 16FL, 16FR, 16RL, 16RR are connected to the circuits 14FL, 14FR, 14RL, 14RR, respectively, from these pressure boosters 15FL, 15FR, 15RL, 15RR to the corresponding wheel cylinders 5FL, 5FR, 5RL, 5RR. These are connected to a common return circuit 17 to the reservoir 2a.
The pressure reducing valves 18FL, 18FR, 18RL, and 18RR are inserted into the circuits 16FL, 16FR, 16RL, and 16RR, respectively.

The pressure increasing valves 15FL, 15FR, 15RL, 15RR and the pressure reducing valves 18FL, 18FR, 18RL, 18RR are all normally closed and are normally closed valves that are opened when turned on.
In the control, by increasing the supply current to the pressure increase valves 15FL, 15FR, 15RL, 15RR, the corresponding brake fluid pressures Pwfl, Pwfr, Pwrl, Pwrr are controlled electronically by increasing the degree of communication with the discharge circuit 11. Can be raised,
By increasing the supply current to the pressure reducing valves 18FL, 18FR, 18RL, 18RR, the corresponding brake fluid pressure Pwfl, Pwfr, Pwrl, Pwrr can be reduced under electronic control by increasing the degree of communication with the return circuit 17. it can.

  A pressure sensor 21 that detects the master cylinder hydraulic pressure Pm is connected to the pipe 4, and pressure sensors 22FL, 22FR, 22RL, and 22RR that individually detect the brake hydraulic pressure Pwfl, Pwfr, Pwrl, and Pwrr are supported. Connected to the circuit 14FL, 14FR, 14RL, 14RR.

The control of the master cut valves 6FL, 6FR, the pressure increase valves 15FL, 15FR, 15RL, 15RR and the pressure reducing valves 18FL, 18FR, 18RL, 18RR, and the sequence control related to the pressure of the pump 8 (accumulator 12) via the motor 10 The microcomputer 30 shown in FIG. 2 performs this via the drive circuit 31,
For this reason, the microcomputer 30 receives the signals from the pressure sensors 13, 21 and the pressure sensors 22FL, 22FR, 22RL, 22RR (shown as one pressure sensor 22 and the brake hydraulic pressure Pw in FIG. 2). In addition to
A signal from the brake switch 23 that is turned on during the braking operation to depress the brake pedal 1, a signal from the acceleration sensor 24 that detects the vehicle longitudinal acceleration G (negative value is deceleration), and a vehicle speed sensor 25 that detects the vehicle speed VSP And a signal from the stroke sensor 26 for detecting the depression stroke St of the brake pedal 1,
The left and right front wheel speeds Vwfl and Pwfr and the left and right rear wheel speeds Pwrl and Pwrr are individually inputted with signals from a wheel speed sensor group 27.

The operation of the hydraulic brake system described above will be described below.
When the microcomputer 30 detects the occurrence of the master cylinder hydraulic pressure Pm, the master cut valves 6FL and 6FR are closed by the ON via the drive circuit 31, and the pressure increase valves 15FL, 15FR, 15RL, 15RR and the pressure reduction Electronic control so that the brake fluid pressures Pwfl, Pwfr, Pwrl, Pwrr (detected values of pressure sensors 22FL, 22FR, 22RL, 22RR) of the corresponding wheels individually become target values by energization control of valves 18FL, 18FR, 18RL, 18RR To do.

  Therefore, when the brake fluid pressure Pwfl, Pwfr, Pwrl, Pwrr is uncontrollable due to a failure of the electronic control system, the microcomputer 30 opens the master cut valves 6FL, 6FR by turning them OFF via the drive circuit 31. The vehicle can be braked by left and right front wheel braking by the master cylinder Pm, and the vehicle can be kept brakeable even in the event of a failure.

The braking control by the microcomputer 30 at the normal time targeted by the present invention is as shown in a functional block diagram in FIG. 3 and in a flowchart in FIG.
FIG. 4 is repeatedly executed by a scheduled interrupt, and various sensor signals are read in step S1.
In step S2 (target deceleration calculation unit 32 in FIG. 3), the master cylinder hydraulic pressure Pm and / or the brake pedal depression stroke St, or both, and the target deceleration calculation for each vehicle specification stored in the ROM in advance. Using the constant K1, the target deceleration tG of the vehicle is calculated by multiplying both.

In step S3 (target deceleration correction value calculation unit 33 in FIG. 3), the target deceleration tG of the vehicle obtained as described above is corrected by the control program shown in FIG. The value tGc is calculated.
In step S11 in FIG. 5, a process for detecting whether or not the road surface causes the wedge effect during wheel braking is performed.
This process is as shown in FIG. 6. First, in step S21, it is checked whether braking is being performed based on whether the brake switch 23 is ON or OFF. If it is not braking, it is not necessary to detect the wedge effect occurrence road surface. The control is terminated as it is.

If it is determined in step S21 that braking is in progress, the wheel speeds Vwfl, Pwfr, Pwrl, and Pwrr are filtered through a bandpass filter in step S22, and then in the next step S23, the wheel speeds are filtered. Fluctuation amounts ΔVwfl, ΔPwfr, ΔPwrl, ΔPwrr are obtained.
Next, in step S24, it is checked whether each wheel is on the wedge effect generation road surface by checking whether these wheel speed fluctuation amounts ΔVwfl, ΔPwfr, ΔPwrl, ΔPwrr are equal to or larger than the set value β for determining the wedge effect generation road surface. .

When it is determined in step S24 that the wheel speed fluctuation amounts ΔVwfl, ΔPwfr, ΔPwrl, ΔPwrr are less than the set value β, that is, when it is determined that the wheel is not on the road surface where the wedge effect occurs, this is indicated in step S25. Thus, the wedge effect occurrence road surface flag FLAG is reset to 0, and in step S26, the resistance force Tr due to the wedge effect that acts to decelerate the vehicle is set to 0.
When it is determined in step S24 that the wheel speed fluctuation amounts ΔVwfl, ΔPwfr, ΔPwrl, ΔPwrr are equal to or larger than the set value β, that is, when it is determined that the wheel is on the road surface where the wedge effect is generated, this is indicated in step S27. Thus, the wedge effect generation road surface flag FLAG is set to 1, and in step S28, the wheel speed fluctuation amounts ΔVwfl, ΔPwfr, ΔPwrl, ΔPwrr are set to the resistance force Tr due to the wedge effect, which acts to decelerate the vehicle. .

  After performing the wedge effect generation road surface detection process (FIG. 6) as described above in step S11 of FIG. 5 corresponding to the resistance force generation means in the present invention, in step S12 of FIG. 5, the wedge effect generation road surface flag FLAG. Whether or not the wheel is on the road surface where the wedge effect occurs is checked based on whether or not is 1, and if it is not on the road surface where the wedge effect occurs, the braking control according to the present invention is unnecessary, and the control is terminated as it is.

When it is determined in step S12 that the wheel is on the road surface where the wedge effect is generated, in step S13 (addition deceleration calculation unit 34 in FIG. 3), the vehicle deceleration (addition) generated due to the resistance force Tr due to the wedge effect. (Deceleration) Ge is obtained by multiplying the resistance force Tr due to the wedge effect by the addition deceleration calculation coefficient α, Ge = Tr × α.
In the next step S14, as shown in FIG. 3, the target deceleration tG obtained in step S2 of FIG. 4 is corrected by raising the addition deceleration Ge due to the wedge effect, and the target deceleration correction value tGc = tG + Ge. Ask for.
Therefore, step S14 corresponds to the braking force control side changing means in the present invention.

In addition, as shown as an input to the addition deceleration calculation unit 34 in FIG. 3, the vehicle acceleration G (negative value is deceleration) detected by the acceleration sensor 24 is used instead of the wheel speed Vwfl, Pwfr, Pwrl, Pwrr, The wedge effect generation road surface can also be detected by the same processing as in FIG.
In addition, when detecting the road surface where the wedge effect occurs, in addition to the above,
When the rate of change in deceleration with respect to the braking slip rate of the wheel is lower than the set rate, it is determined that the road surface has a wedge effect,
When the suspension stroke is greater than or equal to the set stroke, it is determined that the road surface has a wedge effect,
It can also be determined that the road surface has a wedge effect when the braking lock release speed of the wheel during the anti-skid control is equal to or higher than the set speed.

In step S4 (target forward braking torque calculation unit 35 for feedforward control in FIG. 3) after correcting the target deceleration tG and obtaining the target deceleration correction value tGc as described above in step S3 in FIG. A feedforward control target total braking torque tTbff (uniquely determined by multiplying the target deceleration correction value tGc by a calculation constant) required to achieve the target deceleration correction value tGc is obtained.
In the next step S5 (braking torque feedback compensation amount calculation unit 36 in FIG. 3), this deviation is basically calculated based on the deviation ΔG = tGc−G of the actual deceleration detection value G with respect to the target deceleration correction value tGc. Without this, the braking torque feedback compensation amount ΔTbfb necessary to make the actual deceleration G coincide with the target deceleration correction value tGc is calculated.

The above-described calculation of the braking torque feedback compensation amount ΔTbfb is performed as shown in FIG.
First, in step S31, it is detected whether or not the road surface has a wedge effect by the same process as in step S11 of FIG. 5, and in step S32, based on this detection result, the same as in step S12 of FIG. Then, it is checked whether the wheel is on the wedge effect occurrence road surface by checking whether the wedge effect occurrence road surface flag FLAG is 1.

When it is determined in step S32 that the road surface is on the wedge effect occurrence road surface, in step S33, the deceleration deviation limit value ΔG (LIM) related to the deceleration deviation ΔG used for calculating the braking torque feedback compensation amount ΔTbfb is calculated using the calculation coefficient γ. And ΔG (LIM) = (− γ / Tr) based on the resistance force tr due to the wedge effect.
Here, the deceleration deviation limit value ΔG (LIM) changes as illustrated in FIG. 8 according to the resistance force tr due to the wedge effect, and the deceleration deviation limit value ΔG (LIM) as the resistance force tr due to the wedge effect increases. Becomes smaller.
If it is determined in step S32 that the road surface is not on the road where the wedge effect occurs, the deceleration deviation limit value ΔG (LIM) is fixed to the minimum value ΔG (MIN) in step S34.

After determining the deceleration deviation limit value ΔG (LIM) as described above, in step S35 corresponding to the excessive deceleration detecting means in the present invention, the target deceleration correction value tGc (step S14 in FIG. 5), The actual deceleration deviation ΔG = tGc−G with the actual deceleration detection value G is obtained.
In the next step S36, the larger one of the actual deceleration deviation ΔG and the deceleration deviation limit value ΔG (LIM) obtained in steps S33 and S34 is set to the limited deceleration MAX {ΔG, ΔG (LIM)}. The deviation is defined as LimΔG.

  When the actual deceleration deviation ΔG changes over time as shown by the thick wavy line in FIG. 9 and the deceleration deviation limit value ΔG (LIM) is shown by the thin wavy line in the figure, the limited deceleration deviation When LimΔG is represented by a thick solid line, LimΔG = ΔG until instant t1 where ΔG> ΔG (LIM), and LimΔG = ΔG (LIM) after instant t1 where ΔG <ΔG (LIM).

  In the next step S37, the braking deceleration feedback compensation amount ΔTbfb necessary to make the actual deceleration G coincide with the target deceleration correction value tGc is obtained by multiplying the limited deceleration deviation LimΔG by the feedback control gain Gain.

  After obtaining the braking torque feedback compensation amount ΔTbfb as described above, the control returns to step S6 in FIG. 4, where, as shown in FIG. 3, the braking torque feedback compensation amount ΔTbfb is used as the target total braking for feedforward control. The final target total braking torque tTb is obtained by adding to the torque tTbff.

  In the following steps S7 to S10 (each wheel braking torque distribution unit 37 in FIG. 3) corresponding to the wheel braking force distribution control means in the present invention, the vehicle target total braking torque tTb obtained as described above is obtained. By distributing the left front wheel braking force, the right front wheel braking force, the left rear wheel braking force, and the right rear wheel braking force by a predetermined calculation, which will be described later, the respective target braking torques are obtained, and each wheel corresponds. Brake fluid pressure control is performed individually to generate the target braking torque.

By the way, in this embodiment, as schematically shown in FIG. 3, the target deceleration correction value tGc corrected by raising the target deceleration tG by the addition deceleration Ge due to the wedge effect, and the vehicle deceleration detection value G In accordance with the deceleration deviation ΔG = tGc−G during this period, the wheel braking force is controlled so that this deceleration deviation is eliminated, that is, the vehicle deceleration G becomes the target deceleration correction value tGc.
During the braking force control, if a resistance force Tr (step S28 in FIG. 6) that generates an additional deceleration Ge due to the wedge effect is generated between the wheel and the road surface other than the deceleration force due to normal friction, the additional deceleration is generated. When the deceleration detection value G including Ge exceeds the target deceleration tG, the feedback control system is switched to the braking force control excluding the deceleration Ge based on the resistance force Tr due to the wedge effect.
After this switching, it is possible to perform efficient braking force control that effectively uses the resistance force Tr due to the wedge effect.
Therefore, when the driver increases the brake pedal for more braking force, in addition to the braking force corresponding to the road surface friction force, the braking force associated with the resistance force Tr due to the wedge effect is obtained, and the road surface friction is obtained. The above-described conventional problem that only the braking force corresponding to the force can be obtained can be solved.

Further, in the present embodiment, in order to achieve the above-described effect, the normal braking force control law in which the deceleration deviation ΔG in the feedback control system is the deviation between the target deceleration tG and the detected deceleration value G is obtained from the target braking force control law. Braking force control law where the deviation between the target deceleration correction value tGc corrected by raising the deceleration tG by the deceleration Ge based on the resistance force Tr due to the wedge effect and the detected deceleration value G is the deceleration deviation ΔG In order to use the method of changing the braking force control law,
The above-described operation and effect can be achieved reliably by a simple and inexpensive method in which the target deceleration correction value tGc is used instead of the target deceleration tG.

Further, in this embodiment, as described above with reference to FIG. 7, as illustrated in FIGS. 8 and 9, the deceleration deviation ΔG between the target deceleration correction value tGc and the deceleration detection value G is added to the deceleration deviation. Since a limit that does not exceed the limit value ΔG (LIM) is applied, the feedback compensation amount of the wheel braking force that exceeds the limited deceleration deviation LimΔG is not given.
It is possible to limit the feedback compensation amount of the braking force due to disturbances such as the wedge effect and to reduce the braking force, and to prevent the braking force from being reduced due to disturbances, and to make the above-mentioned effects more remarkable. Can do.

  Since the deceleration deviation limit value ΔG (LIM) is reduced as the resistance force Tr due to the wedge effect is increased as illustrated in FIG. 8, the above-described operation and effect are affected by the magnitude of the resistance force Tr due to the wedge effect. Regardless of this, it can be achieved reliably at all times and appropriately without excessively reducing the deceleration deviation limit value ΔG (LIM).

  In step S7 to step S10 in FIG. 4 (each wheel braking torque distribution unit 37 in FIG. 3), the target total braking torque tTb of the vehicle is set to the left front wheel braking force, the right front wheel braking force, and the left rear wheel braking force. When allocating to the right rear wheel braking force and obtaining each target braking torque, the distribution is not performed according to only the target deceleration tG as in the prior art. The distribution is preferably performed according to the resistance force Tr due to the effect.

  As a first example, the braking force of the front wheels is the braking force of the rear wheels, where the wheel load becomes heavy due to load movement during braking, downhill traveling, and unbalanced front and rear loads, and the resistance force Tr due to the wedge effect increases. It is conceivable to distribute the braking force between the wheels so that the difference in braking force between the front and rear wheels increases as the resistance force Tr due to the wedge effect increases.

  In this case, the braking force of the vehicle as a whole is increased by increasing the braking force of the front wheel having a large resistance force Tr due to the wedge effect, and by increasing the braking force difference between the front and rear wheels as the resistance force Tr due to the wedge effect increases. The increase effect is remarkable, which is in good agreement with the purpose of giving priority to an increase in braking force.

As a second example, the braking force of the other right wheel or left wheel is greater than the braking force of the left wheel or right wheel that causes the wheel load to become heavy due to load imbalance in the vehicle width direction and the resistance force Tr due to the wedge effect to increase. It is conceivable to distribute the braking force between the wheels so that
Thus, when the resistance force Tr due to the wedge effect is increased on one side of the left and right wheels, and the resistance force Tr due to the wedge effect is decreased on the other side, the vehicle can Running stability is hindered by the moment,
By increasing the wheel braking force on the side where the resistance force Tr is smaller than the wheel braking force on the side where the resistance force Tr is large as in this example, the above yaw moment is offset and the running stability of the vehicle is improved. Can do.

As a third example, the wheel load becomes heavier due to load movement during turning, and the resistance force Tr due to the wedge effect is increased, so that the braking force of the inner wheel in the turning direction becomes larger than the braking force of the outer wheel in the turning direction. It is conceivable to distribute the braking force.
Thus, when turning, the outer wheel in the turning direction increases the resistance force Tr due to the wedge effect, and the inner wheel in the turning direction decreases the resistance force Tr due to the wedge effect. It tends to oversteer,
As shown in this example, the braking force on the inner wheel in the turning direction is larger than the braking force on the outer wheel in the turning direction that increases the resistance force Tr, thereby offsetting the difference in the resistance force Tr and mitigating the oversteer tendency of the vehicle. Or can be resolved.

  Needless to say, the braking force distribution control described above can be applied not only individually but also in an arbitrary combination, and can be used properly according to the driving state of the vehicle.

1 is a control system diagram showing a hydraulic brake device for a vehicle including a braking control device according to an embodiment of the present invention. It is a block diagram of the control system in the hydraulic brake device. FIG. 3 is a block diagram according to function of the microcomputer in FIG. 2. It is a flowchart which shows the main routine of the braking control program which the microcomputer performs. It is a flowchart which shows the subroutine regarding the target deceleration correction process in the main routine. It is a flowchart which shows the detection program of the wedge effect generation | occurrence | production road surface in the subroutine. 5 is a flowchart showing a subroutine related to a calculation process of a braking torque feedback compensation amount in the main routine of FIG. It is a change characteristic figure which illustrates the deceleration deviation limit value calculated in the subroutine. It is a time chart which illustrates the time series change of the limited deceleration deviation calculated | required in the same subroutine.

Explanation of symbols

1 Brake pedal 2 Master cylinder
3,4 Front wheel brake hydraulic piping
5FL left front wheel wheel cylinder
5FR right front wheel wheel cylinder
5RL Left rear wheel wheel cylinder
5RR right rear wheel wheel cylinder
6FL, 6FR Master cut valve 7 Stroke simulator 8 Pump
10 Motor
12 Accumulator
13 Pressure switch
15FL, 15FR, 15RL, 15RR Booster valve
17 Return circuit
18FL, 18FR, 18RL, 18RR Pressure reducing valve
21 Pressure sensor
22FL, 22FR, 22RL, 22RR Pressure sensor
23 Brake switch
24 Accelerometer
25 Vehicle speed sensor
26 Brake stroke sensor
27 Wheel speed sensor group
30 Microcomputer
31 Drive circuit
32 Target deceleration calculation unit
33 Target deceleration correction value calculator
34 Addition deceleration calculation unit
35 Target total braking torque calculator for feedforward control
36 Brake torque feedback compensation amount calculator
37 Wheel braking torque distribution part

Claims (10)

The wheel braking force is controlled so that the vehicle deceleration becomes the target deceleration according to the deceleration deviation between the target deceleration obtained from the braking operation state of the vehicle and the detected deceleration value of the vehicle. In the device
During the control of the wheel braking force, it is detected that a resistance force that decelerates the vehicle other than the deceleration force due to friction is generated between the wheel and the road surface, and when the deceleration detection value exceeds the target deceleration, A vehicle braking control apparatus configured to limit the vehicle deceleration to the target deceleration according to a deceleration deviation caused by controlling the wheel braking force. The wheel braking force is controlled so that the vehicle deceleration becomes the target deceleration according to the deceleration deviation between the target deceleration obtained from the braking operation state of the vehicle and the detected deceleration value of the vehicle. In the device
During the control of the wheel braking force, a resistance force generation detecting means for detecting the occurrence of a resistance force for decelerating the vehicle other than the deceleration force due to friction between the wheel and the road surface;
An excessive deceleration detection means for detecting that the deceleration detection value exceeds the target deceleration;
By these means, when the generation of the resistance force is detected and a large deceleration detection value exceeding the target deceleration is detected, the deceleration due to the resistance force is excluded instead of the control of the wheel braking force. A braking control device for a vehicle, comprising: braking force control law changing means for changing the braking force control law so as to switch to the braking force control. In the vehicle braking control device according to claim 2,
The resistance force generation detection means, when the fluctuation amount of the speed information regarding the wheel speed and deceleration is greater than or equal to the set amount, or when the rate of change of the deceleration with respect to the braking slip rate of the wheel is lower than the set rate, or It is determined that the resistance force is generated when the suspension stroke is equal to or greater than a set stroke or when the braking lock release speed of the wheel during anti-skid control is equal to or greater than the set speed. Braking control device. In the vehicle braking control device according to claim 3,
The resistance force generation detecting means determines the generation of the resistance force from the wheel speed fluctuation amount equal to or greater than the set amount, and obtains the vehicle deceleration due to the resistance force from the wheel speed fluctuation amount.
The braking force control law changing means changes the braking force control law by raising the target deceleration by the vehicle deceleration due to the resistance force and using it for braking force control of the wheels. A vehicle braking control device. In the vehicle braking control device according to claim 4,
The braking force control law changing means sets a limit on a deceleration deviation between a target deceleration correction value obtained by raising the target deceleration by a vehicle deceleration due to the resistance force and the detected deceleration value. A braking control device for a vehicle, characterized in that a feedback control amount of a wheel braking force exceeding a determined deceleration deviation is not given. In the vehicle braking control device according to claim 5,
The braking force control law changing means sets a limit on a deceleration deviation between a target deceleration correction value obtained by raising the target deceleration by a vehicle deceleration due to the resistance force and the detected deceleration value. A braking control apparatus for a vehicle, wherein the limited deceleration deviation is reduced as the resistance force increases. In the braking control device for a vehicle according to any one of claims 1 to 6,
A braking control device for a vehicle, comprising a wheel braking force distribution control means for determining a wheel braking force distribution according to the resistance force. In the vehicle braking control device according to claim 7,
The vehicle braking force distribution control means performs the braking force distribution control between the wheels so that the braking force of the front wheels becomes larger than the braking force of the rear wheels as the resistance force increases. Control device. The vehicle braking control device according to claim 7 or 8,
The inter-wheel braking force distribution control means is configured such that the braking force of the other right wheel or the left wheel is greater than the braking force of the left wheel or the right wheel where the wheel load becomes heavy due to load imbalance in the vehicle width direction and the resistance force increases. A braking control device for a vehicle, which performs a braking force distribution control between wheels so as to increase to ensure the running stability of the vehicle. In the vehicle braking control device according to any one of claims 7 to 9,
The inter-wheel braking force distribution control means is configured so that the braking force of the inner wheel in the turning direction becomes larger than the braking force of the outer wheel in the turning direction, where the wheel load becomes heavier due to load movement during turning and the resistance force is increased. A braking control device for a vehicle, which performs an inter-braking force distribution control to correct an oversteer tendency.

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