JP2003335234A - Brake control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To keep braking force control within a proper range when the deceleration of a car body is erroneously detected. <P>SOLUTION: A value obtained by adding a braking torque command value feedforward term T<SB>d-</SB>FF as target deceleration α<SB>dem</SB>corresponding to master cylinder pressure P<SB>mc</SB>to a braking torque command value feedback term T<SB>d-</SB>FB corresponding to a difference between the target deceleration α<SB>dem</SB>and a body deceleration αV is defined as a braking torque command value T<SB>d-com</SB>. When the master cylinder pressure P<SB>mc</SB>is a preset value P<SB>mc0</SB>or larger, namely, the target deceleration α<SB>dem</SB>is a preset value or larger, values obtained by multiplying the braking torque command value feedforward term T<SB>d-</SB>FF by coefficients KLU<SB>2</SB>, KLL<SB>2</SB>, respectively, are set as an upper limit value T<SB>d-</SB>FBUL and a lower limit value T<SB>d-</SB>FBLL for the braking torque command value feedback term. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a braking control device for detecting a deceleration acting on a vehicle and controlling a braking force based on the detected deceleration.

[0002]

2. Description of the Related Art An example of such a braking control device is disclosed in Japanese Patent Application Laid-Open No. 56-33254. In this braking control device, the deceleration acting on the vehicle is detected, and the braking force is so-called feedback-controlled based on the detected deceleration.

[0003]

However, in the above-mentioned conventional braking control device, the deceleration acting on the vehicle is fed back to perform the braking force control. Therefore, for example, the vehicle deceleration is calculated from the wheel rotation speed. In this case, if the wheel rotation speed changes due to the unevenness of the road surface or the fluctuation of the road friction coefficient state, the vehicle deceleration cannot be correctly detected, and there is a problem that appropriate braking force control cannot be executed.

The present invention was developed to solve these problems, and provides a braking control device capable of executing appropriate braking force control even when the vehicle deceleration cannot be correctly detected due to disturbance. It is intended to be provided.

[0005]

In order to achieve the above object, a braking control device according to claim 1 of the present invention comprises a target deceleration setting means for setting a target deceleration from an occupant's braking operation amount. A deceleration detecting means for detecting a deceleration occurring in the vehicle, a braking means for applying a braking force to each wheel, and a braking force command value for setting an upper limit value and a lower limit value of the braking force command value to the braking means. A braking force command value is set from a lower limit value setting means, a reference value according to the target deceleration set by the target deceleration setting means, and a correction amount according to the deceleration detected by the deceleration detection means. In addition, the braking force command value is limited by the upper limit value and the lower limit value of the braking force command value set by the braking force command value upper and lower limit value setting means, and the braking means is based on the limited braking force command value. Control that controls the braking force applied to each wheel by And a braking force command value upper and lower limit value setting means, when the target deceleration set by the target deceleration setting means is greater than or equal to a predetermined value, the braking force command value upper and lower limit value setting means sets a reference value according to the target deceleration. Is set to set the upper limit value and the lower limit value of the correction amount, thereby setting the upper limit value and the lower limit value of the braking force command value.

According to a second aspect of the present invention, in the braking control device according to the first aspect of the invention, the braking force command value upper and lower limit value setting means is a target set by the target deceleration setting means. When the deceleration is less than the predetermined value,
By setting a predetermined constant value to the upper limit value and the lower limit value of the correction amount, the upper limit value and the lower limit value of the braking force command value are set.

Further, in a braking control device according to a third aspect of the present invention, in the invention of the first aspect, the braking force command value upper / lower limit value setting means is a target set by the target deceleration setting means. When the deceleration is less than the predetermined value, an addition value of a multiplication value obtained by multiplying a reference value according to the target deceleration by a predetermined ratio and a predetermined constant value is set as the upper limit value and the lower limit value of the correction amount. By doing so, the upper limit value and the lower limit value of the braking force command value are set.

Further, in the braking control device according to a fourth aspect of the present invention, in the invention of the first aspect, the braking force command value upper and lower limit value setting means is a predetermined constant value, and the upper limit of the added value. It is characterized by setting a value and a lower limit value.

[0009]

According to the braking control device of the first aspect of the present invention, the target deceleration is set from the braking operation amount of the occupant and the deceleration generated in the vehicle is detected to detect the occupant. During the braking operation of, while setting the braking force command value from the reference value according to the target deceleration and the correction amount according to the deceleration,
When the target deceleration is equal to or higher than a predetermined value, the braking command value is controlled by limiting the braking command value with the upper and lower limits set by multiplying the reference value according to the target deceleration by a predetermined ratio. Therefore, when the target deceleration is equal to or more than the predetermined value, even when the detected deceleration is not correct, the braking force command value based on it can be limited, and when the target deceleration is less than the predetermined value, By setting the upper and lower limits of the correction amount to be large, an appropriate braking force can be generated by the braking force control, and the braking force control can be set within an appropriate range.

According to a second aspect of the present invention, when the target deceleration is less than the predetermined value, predetermined constant values are set as the upper limit value and the lower limit value of the correction amount. Therefore, since the upper limit value and the lower limit value of the braking force command value are set, when the target deceleration is less than the predetermined value, even if the detected deceleration is not correct, the braking force command value based on it is set. It is possible to prevent the occupant from feeling uncomfortable by controlling the amount of change to a small amount, generate an appropriate braking force by the braking force control, and bring the braking force control into an appropriate range.

Further, according to the braking control device of the third aspect of the present invention, when the target deceleration is less than the predetermined value, the reference value corresponding to the target deceleration is multiplied by a predetermined ratio. By setting the added value of the value and a predetermined constant value to the upper limit value and the lower limit value of the correction amount, the upper limit value and the lower limit value of the braking force command value are set. Even when an incorrect deceleration is detected, the amount of change in the braking force command value based on the detected deceleration can be limited to a smaller amount, and the occupant's discomfort can be suppressed.

Further, according to the braking control device of the fourth aspect of the present invention, the target deceleration is less than the predetermined value because the upper limit value and the lower limit value of the addition value are set at predetermined constant values. Even if the detected deceleration is incorrect, the amount of change in the braking force command value based on it can be limited to a small amount to prevent the occupant from feeling uncomfortable, and the braking force control can provide an appropriate braking force. Can be generated and the braking force control can be set within an appropriate range.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic system configuration diagram showing an embodiment of the present invention, in which regenerative energy is efficiently recovered by controlling the braking fluid pressure while the regenerative braking torque is controlled by an AC synchronous motor. The braking control device of the present invention is applied to a braking control system.

In FIG. 1, a brake pedal 1 operated by a driver is connected to a master cylinder 3 via a booster 2. The booster 2 boosts the pedal effort by using the high-pressure braking fluid pressure accumulated in the accumulator 22 and supplied to the master cylinder 3 by the pump 21. The pump 21
Are sequence-controlled by the pressure switch 23. Further, reference numeral 4 in the drawing is a reservoir for the damping fluid.

The master cylinder 3 is connected to the wheel cylinder 5 of each wheel 10, but in the middle of its braking fluid path, it is switched to the stroke simulator 6 having a fluid load equivalent to that of the wheel cylinder 5. The stroke simulator switching valve 7 is installed. That is, when the stroke simulator switching valve 7 is not energized, the master cylinder 3 is connected to each wheel cylinder 5, but when the stroke simulator switching valve 7 is energized, the master cylinder 3 is connected to the stroke simulator 6 and each wheel cylinder 5 is connected. Is disconnected from the braking fluid pressure in the master cylinder 3.

Along with the operation of the stroke simulator switching valve 7, a pressure increasing valve 8 for supplying the output pressure of the pump 21 or the accumulated pressure of the accumulator 22 to each wheel cylinder 5 to increase the pressure, and a braking fluid for each wheel cylinder 5. Pressure reducing valve 9 for reducing the pressure by reducing the pressure to the reservoir 4
Is provided. Among these, the pressure increasing valve 8 disconnects each wheel cylinder 5 from the pump 21 or the accumulator 22 when not energized, and connects each wheel cylinder 5 to the pump 21 or accumulator 22 when energized. Further, the pressure reducing valve 9 shuts off each wheel cylinder 5 and the reservoir 4 when not energized, and connects each wheel cylinder 5 and the reservoir 4 when energized. Therefore, when each wheel cylinder 5 is separated from the master cylinder 3 by the stroke simulator switching valve 7 and the pressure increasing valve 8 is energized, the braking fluid of each wheel cylinder 5 is separated from the output pressure of the master cylinder 3. The pressure can be increased,
By energizing the pressure reducing valve 9, the braking fluid pressure in each wheel cylinder 5 can be reduced.

The braking fluid pressure circuit has a master cylinder pressure sensor 1 for detecting the output pressure of the master cylinder 3.
1 and a wheel cylinder pressure sensor 12 for detecting the braking fluid pressure of each wheel cylinder 5 separated from the master cylinder 3 by the stroke simulator switching valve 7, and the braking fluid detected by these pressure sensors 11, 12 is provided. Using the pressure, the stroke simulator switching valve 7, the pressure increasing valve 8 and the pressure reducing valve 9 are controlled by a command from the braking fluid pressure control unit 13.

An AC synchronous motor, a so-called motor generator 15, is connected to a front wheel 10 of the wheels 10 corresponding to a drive wheel via a gear box 14. This motor generator 15 drives the wheels 10 as an electric motor by the electric power supplied from the battery 16, and
By the road surface driving torque from the wheels 10, the battery 16 can be charged with electricity as a generator. This battery 16
An AC current control circuit, a so-called inverter 17, is interposed between the motor generator 15 and the motor generator 15, and converts AC current and DC current according to a command (three-phase PWM signal) from the motor control unit 18. The drive torque control of the motor generator 15 and the battery 1 of the kinetic energy of the vehicle by the regenerative braking control are thereby performed.
Recovery to 6 can be performed.

The braking fluid pressure control unit 13
Also, the motor control unit 18 is connected to the regenerative cooperative brake control control unit 19 via a communication line. The braking fluid pressure control unit 1
3 and the motor control unit 18, of course,
Although it is possible to control the braking fluid pressure of the wheel cylinder 5 and the rotation state of the motor generator 15 alone,
By controlling them in accordance with a command from the regenerative cooperative brake control control unit 19, it becomes possible to more efficiently collect the kinetic energy of the vehicle and improve the fuel consumption.

Specifically, the motor control unit 18 is the regenerative cooperative brake control control unit 1
Based on the regenerative braking torque command value received from 9,
While controlling the regenerative braking torque, the maximum allowable regenerative torque value calculated from the state of charge of the battery 16, the temperature, etc. is calculated and transmitted to the regenerative cooperative brake control control unit 19. The braking fluid pressure control unit 13 controls the braking fluid pressure of each wheel cylinder 5 in accordance with the braking fluid pressure command value received from the regenerative cooperative brake control control unit 19, and the master cylinder pressure sensor 11 and the wheel cylinders. The master cylinder pressure and the wheel cylinder pressure detected by the pressure sensor 12 are transmitted to the regenerative cooperative brake control control unit 19. In order to calculate the regenerative brake torque and the braking fluid pressure command value in the regenerative cooperative brake control control unit 19, the vehicle has a drive wheel speed for detecting the rotational speed of the wheel (front wheel) 10 corresponding to the drive wheel. A sensor 20 is provided.

Each control unit such as the braking fluid pressure control unit 13 and the motor control unit 18 including the regenerative cooperative brake control control unit 19 is provided with an arithmetic processing unit such as a microcomputer. The unit 13 and the motor control unit 18 create a drive signal and a control signal according to each command value, and output them to the above-mentioned actuators. On the other hand, the regenerative cooperative brake control control unit 19 calculates the braking fluid pressure command value and the regenerative torque command value that can obtain the deceleration that matches the driver's intention and that has the highest vehicle kinetic energy recovery efficiency. , To the braking fluid pressure control unit 13 and the motor control unit 18, respectively.

Next, a method for calculating the braking torque command value Td-com from the target deceleration αdem in order to calculate the braking fluid pressure command value and the regenerative torque command value performed in the regenerative cooperative brake control control unit 19. Will be described with reference to the block diagram of FIG. For example, the target deceleration α dem
Is the driver's brake pedal depression amount (braking operation amount),
That is, assuming that the value is proportional to the master cylinder pressure Pmc, a feedforward term corresponding only to the target deceleration αdem and a feedback term obtained by feeding back the deceleration actually occurring in the vehicle are obtained, and those The summed value is the braking torque command value Td-com.

In FIG. 2, the block B4 (response characteristic P
(s)) corresponds to your vehicle. ΑV in the figure is the deceleration achieved or generated by the host vehicle. Here, when the deceleration immediately before the start of braking, for example, the deceleration due to the engine braking force, the deceleration on the uphill road, or the acceleration on the downhill road is taken as the reference deceleration αB, the deceleration αV generated by the host vehicle
The value (αV−αB) obtained by subtracting the reference deceleration αB from
It is the deceleration that should be achieved by the braking control system.

In the block diagram of FIG. 2, first, in block B1, the target deceleration αdem is set in order to match the response characteristic Pm (s) of the subject vehicle model to be controlled with the reference model characteristic Fref (s). On the other hand, the feedforward compensator (phase compensator) CFF (s) processing shown in the following equation 1 is performed to calculate the feedforward term Td-FF of the braking torque command value. Note that K2 in the equation is a vehicle parameter constant for converting the target deceleration αdem into braking torque.

[0025]

[Equation 1]

On the other hand, in order to calculate the feedback term Td-FB of the braking torque command value, first, in block B2, the target deceleration αdem is subjected to the reference model characteristic Fref (s) process shown in the following two equations to obtain the reference. Calculate the deceleration rate α ref.

[0027]

[Equation 2]

The reference deceleration αre calculated in this way
From f, a difference (αV−αB) between the deceleration αV generated in the host vehicle and the reference deceleration αB is subtracted by an adder / subtractor to calculate a deceleration feedback difference value Δα. Then, for the feedback difference value Δα of this deceleration, the block B3
Then, the feedback compensator CFB (s) processing shown in the following three equations is performed to calculate the feedback term Td-FB of the braking torque command value. The feedback compensator CFB (s)
Is a basic PI (proportional-integral) controller, and the control constants KP and KI in the equation are set in consideration of the gain margin and the phase margin.

[0029]

[Equation 3]

Therefore, the feedforward term Td-FF of the braking torque command value and the feedback term Td-FB of the braking torque command value are added by the adder to obtain the braking torque command value Td-.
com can be calculated. Next, the calculation processing for calculating the braking fluid pressure command value and the regenerative torque command value performed in the regenerative cooperative brake control control unit 19 will be described with reference to the flowchart of FIG.

This calculation process is performed for a predetermined time ΔT (for example, 1
It is executed as a timer interrupt process every 0 msec. It should be noted that although no particular steps are provided for communication in this flowchart, the information obtained by the calculation is stored as needed, and the stored information is read as needed. In this calculation process, first, in step S1, the master cylinder pressure Pmc detected by the master cylinder pressure sensor 11 and each wheel cylinder pressure Pwc detected by the wheel cylinder pressure sensor 12 are read from the braking fluid pressure control unit 13. .

Next, in step S2, the drive wheel speed detected by the drive wheel speed sensor 20 is read as the traveling speed of the vehicle, and the bandpass filter represented by the transfer function Fbpf (s) of the following four equations is used. The processing is performed to obtain the driving wheel deceleration, which is used as the vehicle deceleration αV generated in the actual vehicle. However, in the equation, ω is a natural angular frequency, and ζ is a damping constant.

[0033]

[Equation 4]

Next, in step S3, the maximum regenerative torque Tmmax available from the motor control unit 18 is read. Next, in step S4, the master cylinder pressure Pmc read in step S1 is multiplied by a predetermined constant K1, and the negative value is calculated as the target deceleration αdem.

Next, in step S5, an estimated value of deceleration due to the engine braking force and an estimated engine brake deceleration value αeng are calculated. Specifically, first, the driving wheel speed read in step S2 is set as the traveling speed of the vehicle,
Based on the traveling speed and the shift position, the engine braking force (in the figure, the braking force) is calculated according to the control map of FIG. 4a.
Obtain an estimated value or target value Feng. At the same time, the running resistance Freg on a flat road is obtained from the running speed of the host vehicle according to the control map of FIG. 4b. Then, the sum of them is divided by the average vehicle weight MV to calculate the engine brake deceleration estimated value αeng.

Next, in step S6, the target deceleration αdem calculated in step S4 is subjected to the feedforward compensator (phase compensator) CFF (s) process of the above equation 1 to perform the braking torque command value. Feedforward term of Td-
Calculate FF. Next, in step S7, the brake pedal is turned on by using whether or not the master cylinder pressure Pmc read in step S1 is a relatively small predetermined value or more. It is determined whether or not it is in the (braking operation) state. If it is in the brake pedal on state, the process proceeds to step S9, and if not, the process proceeds to step S8.

In step S8, the deceleration α0 immediately before the brake operation and the engine brake deceleration reference value αeng0 are updated, and then the process proceeds to step S11. In particular,
When the braking start time TJ from the accelerator pedal release operation, that is, from the accelerator off to the braking operation, that is, the brake on, is obtained, and when the braking start time TJ is, for example, a predetermined value TJ0 or more equivalent to the time when the engine braking force converges, The vehicle deceleration αV calculated in step S2 is set as the deceleration α0 immediately before the brake operation, and
The engine brake deceleration estimated value αeng calculated in 5 is set as the engine brake deceleration reference value αeng0. When the braking start time TJ is less than the predetermined value TJ0, the engine brake deceleration estimated value αeng calculated in step S5 is set as the deceleration α0 immediately before the brake operation, and the engine brake deceleration estimated value αeng is set. Set the engine brake deceleration reference value αeng0. That is, when the braking start time TJ is equal to or greater than the predetermined value TJ0 corresponding to the engine brake convergence required time, the actual vehicle deceleration αV is set to the deceleration α0 immediately before the braking operation, and when it is less than the predetermined value TJ0, it may occur thereafter. Let the estimated engine brake deceleration rate αeng be the deceleration rate α0 immediately before braking.

On the other hand, in step S9, the engine brake deceleration estimated value αeng calculated in step S5 is calculated.
Then, the value obtained by subtracting the engine brake deceleration reference value αeng0 from is added to the deceleration α0 immediately before the brake operation to calculate the reference deceleration αB, and then the process proceeds to step S10. In the step S10, the reference deceleration αB calculated in the step S9 is used to set the target deceleration α as described above.
Reference model characteristic Fref (s) expressed by the above equation 2 with respect to dem
The reference deceleration αref is calculated and the difference (αV −αB) between the vehicle deceleration αV and the reference deceleration αB is subtracted from this reference deceleration αref to calculate the feedback difference value Δα of the deceleration. Deceleration feedback difference value Δα
On the other hand, the feedback compensator CFB (s) shown in the above equation 3
The braking torque command value feedback term Td-
After calculating FB, the process proceeds to step S14.

In the step S14, the step S
It is determined whether or not the master cylinder pressure Pmc read in 1 is equal to or greater than a predetermined value Pmc0, that is, the occupant braking operation amount, and at the same time, the magnitude of the target deceleration αdem is equal to or greater than a predetermined value. If the master cylinder pressure Pmc is equal to or higher than the predetermined value Pmc0, the process proceeds to step S15, and if not, the process proceeds to step S16. Here, the predetermined value P
mc0 is a value determined from an experiment in which the braking force command value is changed while the occupant is braking, and the relationship between the minimum change amount that the occupant feels strange and the master cylinder pressure is detected. The minimum value of the amount of change in which the occupant feels uncomfortable is a threshold value that changes according to the master cylinder pressure Pmc.

In the step S15, the step S
The feedforward term Td-FF of the braking torque command value calculated in 6 is multiplied by the coefficients KLU1 and KLL1 smaller than "1" to obtain the upper limit value Td- of the feedback term of the braking torque command value.
After calculating FBUL and the lower limit value Td-FBLL, step S17
Move to. Here, the coefficients KLU1 and KLL1 are set so that even when the detected vehicle body deceleration rate αV is incorrect, the amount of change in the braking torque command value based on the coefficient is limited to prevent the occupant from feeling uncomfortable.

On the other hand, in step S16, the constant CLU is added to the product of the feedforward term Td-FF of the braking torque command value calculated in step S6 multiplied by a coefficient KLU2 smaller than "1", and the braking is performed. The upper limit value Td-FBUL of the feedback term of the torque command value is calculated, and the feedforward term Td-FF of the braking torque command value is calculated as
The constant CLL is added to the product of the coefficient KLL2 smaller than "1".
Is added to calculate the lower limit value Td-FBLL of the feedback term of the braking torque command value, and then the process proceeds to step S17.
Here, the constants CLU and CLL are:
Even when an incorrect vehicle deceleration αV is detected, by limiting the amount of change in the braking torque command value based on it,
It is set so as to prevent the occupant from feeling uncomfortable and to be larger than the minimum braking torque that can be generated by the wheel cylinders 5 and the like.

Further, the coefficients KLU2 and KLL2 are such that when the master cylinder pressure Pmc reaches a predetermined value Pmc0, the upper limit value Td-FBUL of the feedback term multiplies the feedforward term Td-FF of the braking torque command value by the coefficient KLU1. And the lower limit value Td-FBLL of the feedback term is a value obtained by multiplying the feedforward term Td-FF of the braking torque command value by a coefficient KLL1.

In the step S17, the step S
15 or the upper limit value Td-FBUL and the lower limit value Td-FB of the feedback term of the braking torque command value set in step S16
-LL is used to limit the feedback term Td-FB of the braking torque command value calculated in step S10, and then the process proceeds to step S11. In step S11, the feedforward term Td-FF of the braking torque command value calculated in step S6 and the feedback term Td-FB of the braking torque command value calculated in step S10 or limited in step S17 are used. The braking torque command value Td-com is calculated from the sum of the
Allocate to b-com and regenerative braking torque command value Tm-com.
Here, in order to improve the fuel consumption as much as possible, the maximum regenerative torque Tmmax read in step S3 is distributed so as to be used up as much as possible. Since the motor generator 15 of the present embodiment drives only the front wheels and regeneratively brakes by the road surface driving torque from the front wheels, the cases are classified as follows.

First, according to the front and rear wheel braking force distribution control map shown in FIG. 5 (for example, an ideal braking force distribution map, the braking torque is shown by an absolute value), the braking torque command value Td-co
m is distributed to the front wheel braking torque command value Td-com-F and the rear wheel braking torque command value Td-com-R. The sum of the absolute value of the front wheel braking torque command value Td-com-F and the absolute value of the rear wheel braking torque command value Td-com-R, that is, the absolute value of the braking torque command value Td-com is the maximum. When the regenerative torque Tmmax is less than the absolute value, only regenerative braking is performed, and the front wheel braking fluid pressure braking torque command value Tb-com-F and the rear wheel braking fluid pressure braking torque command value Tb-com-R are both set to "0". The regenerative braking torque command value Tm-com is set to the braking torque command value Td-com.

Further, the absolute value of the braking torque command value Td-com is greater than or equal to the absolute value of the maximum regenerative torque Tmmax,
When the absolute value of the front wheel braking torque command value Td-com-F is less than the absolute value of the maximum regenerative torque Tmmax, the regenerative braking and the rear wheel braking fluid pressure braking are performed, and the front wheel braking fluid pressure braking torque command value Tb- com-F is "0", and the rear wheel braking fluid pressure braking torque command value Tb-com-R is a value obtained by subtracting the maximum regenerative torque Tmmax from the braking torque command value Td-com,
Set the regenerative braking torque command value Tm-com to the maximum regenerative torque Tmmax
Set to. Further, the absolute value of the maximum regenerative torque Tmmax is greater than or equal to a predetermined value near "0", and the absolute value of the front wheel braking torque command value Td-com-F is the maximum regenerative torque Tmm.
When the absolute value of ax is greater than or equal to the absolute value of ax, regenerative braking and front and rear wheel braking fluid pressure braking are performed, and front wheel braking fluid pressure braking torque command value Tb-co
mF is the value obtained by subtracting the maximum regenerative torque Tmmax from the front wheel braking torque command value Tdcom-F, and the rear wheel braking fluid pressure braking torque command value Tb-com-R is the rear wheel braking torque command value Td-com-R.
Then, the regenerative braking torque command value Tm-com is set to the maximum regenerative torque Tmmax. When the absolute value of the maximum regenerative torque Tmmax is less than a predetermined value near "0", only the braking fluid pressure braking is performed, and the front wheel braking fluid pressure braking torque command value T
b-com-F is the front wheel braking torque command value Td-com-F, rear wheel braking fluid pressure braking torque command value Tb-com-R is the rear wheel braking torque command value Td-com-R, and the regenerative braking torque command is Value Tm-com
Is set to "0".

Next, in step S12, the predetermined vehicle parameter constant K3 is applied to the braking fluid pressure braking torque command values Tb-com-F and Tb-com-R for the front and rear wheels calculated in step S11.
Multiply by the braking fluid pressure command values for the front and rear wheels Pb-com-F, Pb-co
Calculate mR. Next, the process proceeds to step S13, and the regenerative braking torque command value Tm-co calculated in step S11 is calculated.
m is output to the motor control unit 18, and the braking fluid pressure command values Pb-com-F and Pb-com-R for the front and rear wheels calculated in step S12 are output to the braking fluid pressure control unit 13. Output and then return to the main program.

According to this calculation processing, during the period from the accelerator off to the brake on, the vehicle deceleration αV or the engine brake deceleration estimated value αeng at that time is set as the deceleration α0 immediately before the braking operation, and at that time. While updating the engine brake deceleration estimated value αeng as the engine brake deceleration reference value αengO at any time, the target deceleration αde
Braking torque command value feed forward term for m Td-
FF is calculated. Braking torque command value Td-co in this state
m is the braking torque command value feedforward term Td-
Since it is only FF, it is originally reflected in the vehicle deceleration αV by the engine braking force, and unless the shift down operation is performed, the absolute value is smaller than the value when the brake pedal is depressed. When the absolute value of the braking torque command value Td-com consisting only of the braking torque command value feedforward term Td-FF is less than the absolute value of the maximum regenerative torque Tmmax, as described above, the front wheel braking fluid pressure braking torque command value Tb. -com-F and the rear wheel braking fluid pressure braking torque command value Tb-com-R are both set to "0", and the regenerative braking torque command value Tm-com is set to the braking torque command value Td-com.

On the other hand, when the brake pedal is depressed, the vehicle deceleration αV or the engine brake deceleration estimated value αeng at that time becomes the deceleration α0 immediately before the braking operation.
Also, the engine brake deceleration estimated value αeng at that time is stored as the engine brake deceleration reference value αengO, and the engine brake deceleration reference value αeng0 immediately before the braking operation is used to calculate the engine brake deceleration at that time. Reference deceleration α according to the estimated speed αeng
B is calculated, and a braking torque command value feedback term Td-FB is calculated from the reference deceleration αB, the actual vehicle deceleration αV, and the reference deceleration αref, and the braking torque command value feedforward term Td-FB is calculated. The value obtained by adding FF is the braking torque command value Td-com. At this time, if the time TJ from the accelerator off to the brake on is equal to or greater than the predetermined value TJ0 corresponding to the time when the engine braking force converges, the vehicle deceleration αV at that time is set to the deceleration α0 immediately before the braking operation. There is. Therefore, if the engine braking force, the deceleration on the uphill road, and the acceleration on the downhill road are applied during the braking operation, they appear in the vehicle deceleration αV and are reflected in the deceleration α0 immediately before the braking operation. , The subsequent reference deceleration αB becomes a value that reflects the influence of those acceleration / deceleration, and the braking torque command value feedback term Td-FB corresponding to the difference between the reference deceleration αB and the vehicle deceleration αV.
Is a value that reflects only the fluctuation of the engine brake torque, and as long as the operation amount of the brake pedal is constant and the braking torque command value feedforward term Td-FF is equal or nearly equal, the deceleration intended by the driver is Can be achieved.

Also, when the engine braking force changes due to a downshift or the like during this process, the difference between the engine brake deceleration estimated value αeng at that time and the engine brake deceleration reference value αeng0 is set as the reference deceleration αB. Since it can be reflected, after that, continue to achieve the deceleration intended by the driver based on the braking torque command value feedback term Td-FB according to the difference between the reference deceleration αB and the vehicle deceleration αV. You can

When the time TJ from the accelerator off to the brake on is less than the predetermined value TJ0 corresponding to the time when the engine braking force converges, the engine brake deceleration estimated value αeng is set to the deceleration α0 immediately before the braking operation.
Since it is set to, after the engine braking force converges,
It is possible to achieve the deceleration intended by the driver.

FIG. 6 shows a change with time of the vehicle acceleration / deceleration due to the arithmetic processing of FIG. In this timing chart, the accelerator is off at time t01, the brake is on at time t02, and the downshift is at time t03 while the vehicle is traveling on a flat road at a constant speed. Pmc is constant. When the accelerator is turned off at time t01, deceleration occurs in the vehicle due to the engine braking force, but the value of the deceleration gradually increases (the degree of deceleration decreases) as the vehicle running speed decreases. .

When the brake is turned on at time t02, the vehicle deceleration αV at that time is set to the deceleration α0 immediately before the brake operation, and the engine brake deceleration estimated value αeng at that time becomes the engine brake deceleration reference value αeng0. Is set. Therefore, after this time t02, the deceleration (αV-αeng0) corresponding to the depression amount of the brake pedal is added to the deceleration αB (= α0) until then, but with the subsequent decrease of the own vehicle traveling speed. If the engine brake deceleration estimated value αeng becomes large (the degree of deceleration becomes small), this engine brake deceleration estimated value αeng
And the engine brake deceleration reference value αeng0, the deceleration reference value αB increases (decreases the degree of deceleration) by the difference, and the vehicle is generated by the braking fluid pressure control or the regenerative braking control. The value of deceleration αV increases (decreases as the degree of deceleration) by the amount by which the engine brake torque decreases.

Further, when a downshift is performed at time t03,
The engine brake deceleration estimated value αeng becomes smaller (increased as the degree of deceleration) by that amount, and the deceleration reference is made by the difference between the engine brake deceleration estimated value αeng and the engine brake deceleration reference value αeng0. The value αB becomes small (it becomes large as the degree of deceleration), and the value of the vehicle deceleration αV generated by the braking fluid pressure control or the regenerative braking control becomes small by the increase of the engine brake torque (deceleration It becomes big as a degree). However, since the engine braking force also decreases as the traveling speed decreases thereafter, the value of the vehicle deceleration αV gradually increases (decreases as the degree of deceleration).

By the way, the feedback term Td-FB of the braking torque command value is limited by the upper limit value Td-FBUL and the lower limit value Td-FBLL of the feedback term of the braking torque command value. On the other hand, since the feedforward term Td-FF of the braking torque command value is not limited, it is composed of the sum of the feedforward term Td-FF of the braking torque command value and the feedback term Td-FB of the braking torque command value. In other words, the braking torque command value Td-com is limited by the addition value of the feedforward term Td-FF of the braking torque command value and the upper limit value Td-FBUL and the lower limit value Td-FBLL of the feedback term of the braking torque command value. it can. The addition value of the feedforward term Td-FF of the braking torque command value and the upper limit value Td-FBUL and the lower limit value Td-FBLL of the feedback term of the braking torque command value is the upper limit value Td-comUL and the lower limit value of the braking torque command value. Td-
If comLL, the upper limit value of the braking torque command value Td-co
The mUL and the lower limit value Td-comLL are set with respect to the master cylinder pressure Pmc as shown in FIG. In FIG. 7, the braking torque command value is shown as an absolute value.

That is, in a region where the master cylinder pressure Pmc is equal to or lower than the predetermined value Pmc0, the upper limit value Td-FBUL and the lower limit value Td-FBLL of the feedback term of the braking torque command value are equal to the feedforward term Td of the braking torque command value. -FF to coefficient K
Since it is a value obtained by adding constants CLU and CLL to the product of LU2 and KLL2, the master cylinder pressure Pmc, that is, the feedforward term Td-FF of the braking torque command value that is the target deceleration.
Will increase from the constants CLU and CLL. On the other hand, in the region where the master cylinder pressure Pmc is equal to or higher than the predetermined value Pmc0, it becomes a value obtained by multiplying the feedforward term Td-FF of the braking torque command value by the coefficients KLU2 and KLL2. Therefore, at the master cylinder pressure Pmc, that is, the target deceleration. It will increase linearly as the feedforward term Td-FF of a certain braking torque command value increases.

FIG. 8 shows the upper limit value Td-FBUL and the lower limit value T of the feedback term of the braking torque command value (shown in absolute value).
d-FBLL is always a value obtained by multiplying the feedforward term Td-FF of the braking torque command value by predetermined coefficients KLU2 and KLL2. Therefore, the upper limit value Td-co of the braking torque command value
The mUL and the lower limit value Td-comLL increase as the feedforward term Td-FF of the braking torque command value increases. Here, it is assumed that the brake pedal is depressed at time t01, and the depression of the brake pedal is kept constant at time t02. After that, at time t03, the vehicle body deceleration αV becomes small (numerically Is large). Further, it is assumed that the vehicle body deceleration αV well matches the target deceleration αdem until the time t03, and as a result, the braking torque command value Td-com is almost the braking torque command value Td-FF. And after time t03,
Although the braking torque command value Tdcom is corrected to be small by the feedback term Td-FB of the braking torque command value,
It is limited by the lower limit value Td-comLL of the braking torque command value.

As is clear from the figure, the upper limit value Td-FBUL and the lower limit value Td-FB of the feedback term of the braking torque command value are shown.
LL is always a value obtained by multiplying the feedforward term Td-FF of the braking torque command value by a predetermined coefficient KLU2, KLL2, and the vehicle body deceleration αV is erroneously detected in a region where the braking torque command value Td-com is relatively large. If so, the upper limit value Td-comUL or the lower limit value Td-comLL is set to a relatively small absolute value so that the improper braking torque command value is limited by the upper limit value Td-comUL or the lower limit value Td-comLL. There must be. In this simulation, the vehicle body deceleration αV was erroneously detected when the braking torque command value Td-com was relatively large.
The braking torque command value Td-com is limited by the lower limit value Td-comLL of the appropriate braking torque command value, but if the braking torque command value Td-com is relatively small, the vehicle body deceleration detected correctly is assumed. The braking torque command value Tdcom is calculated by the feedback term Td-FB of the braking torque command value based on αV.
When is corrected to a small value, the braking torque command value may be limited by the upper limit value Td-comUL or the lower limit value Td-comLL, and proper braking force control may not be performed.

In FIG. 9, the master cylinder pressure Pmc is equal to or less than the predetermined value Pmc0, that is, the target deceleration αdem, as in the present embodiment.
Is less than a predetermined value, a predetermined coefficient KU is added to the feedforward term Td-FF of the braking torque command value (shown in absolute value).
The value obtained by adding the constants CLU and CLL to the multiplication value obtained by multiplying L and KLL1 is the upper limit value Td- of the feedback term of the braking torque command value.
FBUL and the lower limit value Td-FBLL, and when the master cylinder pressure Pmc is a predetermined value Pmc0 or more, that is, the target deceleration αdem is a predetermined value or more, the feedforward term Td-FF of the braking torque command value is multiplied by the coefficients KLU2 and KLL2. The values are the upper limit value Td-FBUL and the lower limit value Td- of the feedback term of the braking torque command value.
FBLL. With such a setting, for example, when the vehicle body deceleration αV is erroneously detected in a region where the braking torque command value Td-com is relatively large, an improper braking torque command value is the upper limit value Td-comUL or the lower limit value Td. -Upper limit Td-comUL or lower limit T as limited by comLL
Even if d-comLL has a relatively small absolute value, when the braking torque command value Td-com is relatively small, the constant CLU,
Due to CLL, the upper limit value Td-FBUL and the lower limit value Td-FBLL of the feedback term of the braking torque command value become relatively large absolute values. In this simulation, when the braking torque command value Td-com is relatively large, the vehicle body deceleration αV is erroneously detected, and the braking torque command value Td-com is limited by the lower limit value Td-comLL of the appropriate braking torque command value. However, if the braking torque command value Td-com is relatively small, the braking torque command value Tdcom becomes small due to the feedback term Td-FB of the braking torque command value generated by the correctly detected vehicle deceleration αV. When corrected, the upper limit value Td-comUL or the lower limit value T of the braking torque command value
Appropriate braking force control can be continuously executed without being limited by d-comLL.

Incidentally, in the above embodiment, the master cylinder pressure Pmc is less than or equal to the predetermined value Pmc0, that is, the target deceleration αdem.
Is less than a predetermined value, as shown in FIG. 7, a predetermined coefficient KUL is added to the feedforward term Td-FF of the braking torque command value.
2, the value obtained by adding constants CLU, CLL to the product of multiplication by KLL2, the upper limit value Td-FB of the feedback term of the braking torque command value
Although UL and the lower limit value Td-FBLL are shown as examples, the upper limit value Td-FBUL and the lower limit value Td-FBLL of the feedback term of the braking torque command value when the target deceleration αdem is less than or equal to the predetermined value are the same as those in the above embodiment. However, the upper limit value Td-FBUL and the lower limit value Td-FBLL (both are indicated by absolute values) may be limited by a predetermined constant value, as shown in FIG. As shown in 11, a predetermined constant value may be the upper limit value Td-FBUL and the lower limit value Td-FBLL (both are indicated by absolute values). By doing so, even when the detected vehicle deceleration αV is incorrect, the amount of change in the braking torque command value based on that is limited to a small amount, and the occupant's discomfort can be prevented and prevented. Appropriate braking force can be generated, and braking force control can be performed in an appropriate range.

From the above, step S4 of the arithmetic processing of FIG. 3 constitutes the target deceleration setting means of the present invention, and similarly, the driving wheel speed sensor 20 and step S2 of the arithmetic processing of FIG. 3 are similarly reduced. The pump 21, the pressure increasing valve 8, the pressure reducing valve 9, and the wheel cylinder 5 constitute a speed detecting means, and a braking means, and step S14- of the arithmetic processing of FIG.
Step S16 constitutes a braking force command value upper / lower limit value setting means, and steps S6 to S1 of the arithmetic processing of FIG.
3, step S17 constitutes the braking control means.

[Brief description of drawings]

FIG. 1 is a system schematic configuration diagram showing an example of a braking control device of the present invention.

FIG. 2 is a block diagram of a braking torque command value calculation performed by a regenerative cooperative brake control control unit.

FIG. 3 is a flowchart of a calculation process for calculating a braking fluid pressure command value and a regenerative torque command value based on the calculation of the braking torque command value of FIG.

FIG. 4 is a control map used in the arithmetic processing of FIG.

5 is a control map used in the arithmetic processing of FIG.

FIG. 6 is a timing chart showing changes in vehicle deceleration due to the arithmetic processing of FIG.

FIG. 7 is an explanatory diagram of a braking torque command value set in the calculation process of FIG. 3 and its upper limit value and lower limit value.

FIG. 8 is an explanatory diagram of a braking torque command value when a vehicle deceleration is erroneously detected.

9 is an explanatory diagram of a braking torque command value when a vehicle body deceleration is erroneously detected by the calculation process of FIG.

FIG. 10 is an explanatory diagram of a modified example of the braking torque command value set in the calculation process of FIG. 3 and its upper limit value and lower limit value.

FIG. 11 is an explanatory diagram of a modified example of the braking torque command value and its upper limit value and lower limit value set in the calculation process of FIG.

[Explanation of symbols]

1 is the brake pedal 3 is the master cylinder 5 is a wheel cylinder 6 is a stroke simulator 7 is a stroke simulator switching valve 8 is a pressure increasing valve 9 is a pressure reducing valve 10 is a wheel 11 is a master cylinder pressure sensor 12 is a wheel cylinder pressure sensor 13 is a braking fluid pressure control unit 15 is a motor generator 18 is a motor control unit 19 is a regenerative cooperative brake control control unit 24 is a stroke sensor

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Junji Tsutsumi             Nissan, Takaracho, Kanagawa-ku, Yokohama-shi, Kanagawa Nissan             Inside the automobile corporation (72) Inventor Kazuhiko Tazoe             Nissan, Takaracho, Kanagawa-ku, Yokohama-shi, Kanagawa Nissan             Inside the automobile corporation F term (reference) 3D046 BB17 EE01 EE03 HH02 HH05                       HH16 HH25 HH36 JJ01 JJ04                       KK12 LL02 LL05 LL17

Claims (4)

[Claims] 1. A target deceleration setting means for setting a target deceleration from a braking operation amount of an occupant, a deceleration detecting means for detecting a deceleration generated in a vehicle, and a braking means for applying a braking force to each wheel. A braking force command value upper and lower limit value setting means for setting an upper limit value and a lower limit value of the braking force command value to the braking means, a reference value according to the target deceleration set by the target deceleration setting means, and The braking force command value is set from the correction amount according to the deceleration detected by the deceleration detecting means, and the braking force command value is set by the braking force command value upper and lower limit value setting means. And a lower limit value, and a braking control unit that controls the braking force applied to each wheel by the braking unit based on the limited braking force command value. The means is set by the target deceleration setting means. When the target deceleration is a predetermined value or more, by setting the upper limit value and the lower limit value of the correction amount by multiplying a predetermined ratio to a reference value corresponding to the target deceleration,
A braking control device, wherein an upper limit value and a lower limit value of the braking force command value are set. 2. The braking force command value upper and lower limit value setting means,
When the target deceleration set by the target deceleration setting means is less than the predetermined value, by setting a predetermined constant value to the upper limit value and the lower limit value of the correction amount, the upper limit value of the braking force command value And a lower limit value are set, The braking control device according to claim 1 characterized by things. 3. The braking force command value upper and lower limit value setting means,
When the target deceleration set by the target deceleration setting means is less than the predetermined value, an addition value of a multiplication value obtained by multiplying a reference value according to the target deceleration by a predetermined ratio and a predetermined constant value is used. The braking control device according to claim 1, wherein the upper limit value and the lower limit value of the correction amount are set to set the upper limit value and the lower limit value of the braking force command value. 4. The braking force command value upper and lower limit value setting means,
The braking control device according to claim 3, wherein the upper limit value and the lower limit value of the added value are set at predetermined constant values.