JP2003237556A - Braking controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To limit braking force control in the case of erroneous detection of a vehicle body deceleration in an appropriate range. <P>SOLUTION: When a braking torque command value T<SB>d-com</SB>is defined by adding a braking torque command value feed-forward term T<SB>d-</SB>FF as a target deceleration α<SB>dem</SB>corresponding to a master cylinder pressure P<SB>mc</SB>to a braking torque command value feedback term T<SB>d-</SB>FB corresponding to a differential value between a target deceleration α<SB>dem</SB>and an automobile body deceleration αV, in the case that the master cylinder pressure P<SB>mc</SB>is equal to or less than a predetermined value P<SB>mc0</SB>, a value calculated by multiplying the braking torque command value feed forward term T<SB>d-</SB>FF by coefficient KLU and KLL is regarded as an upper limit value T<SB>d-</SB>FBUL of feedback term and a lower limit value T<SB>d-</SB>FBLL of feedback term and in the case that the master cylinder pressure P<SB>mc</SB>is equal to or more than the predetermined value P<SB>mc0</SB>, a constant value CUL is regarded as the upper limit value T<SB>d-</SB>FBUL of feedback term and CLL is regarded as the lower limit value T<SB>d-</SB>FBLL of feedback term. Thus, the braking torque command value T<SB>d-com</SB>in the case of erroneous detection of an automobile body deceleration is limited in the appropriate range corresponding to the target deceleration α<SB>dem</SB>. <P>COPYRIGHT: (C)2003,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. The deceleration detecting means for detecting the deceleration generated in the vehicle, the braking means for applying the braking force to each wheel, the upper and lower limit values of the braking force command value to the braking means by the target deceleration setting means. A braking command value upper and lower limit value setting means set based on the set target deceleration, a deceleration detected by the deceleration detecting means during the occupant's braking operation, and a target set by the target deceleration setting means. The braking force command value is set based on the deceleration, and the braking force command value 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. Braking force to each wheel by means It is characterized in that a Gosuru braking control means.

According to a second aspect of the present invention, in the braking control device according to the first aspect of the present invention, the braking control means corresponds to the target deceleration set by the target deceleration setting means. A braking force command value is calculated from an addition value of one braking force command value and a second braking force command value corresponding to the deceleration detected by the deceleration detecting means, and the braking command value upper and lower limit values are also calculated. The setting means sets the upper limit value and the lower limit value of the braking force command value by multiplying the first braking force command value by a predetermined ratio and setting the upper limit value and the lower limit value of the second braking force command value. It is characterized by doing.

According to a third aspect of the present invention, in the braking control apparatus according to the third aspect of the invention, the braking command value upper / lower limit value setting means is the target deceleration setting means. When the speed is equal to or higher than a predetermined value, the upper limit value and the lower limit value of the second braking force command value are set to constant values.

[0008]

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, the braking command value is calculated based on the detected deceleration and the target deceleration, and the braking command value is limited to the upper and lower limit values set according to the target deceleration to Since the braking force is controlled, even when the detected deceleration is incorrect, the braking force control can be set within an appropriate range by limiting the braking command value based on the detected deceleration.

According to the braking control device of the second aspect of the present invention, the first braking force command value according to the target deceleration and the second braking force command value according to the detected deceleration. Since the braking force command value is calculated from the added value with the value and the upper limit value and the lower limit value of the second braking force command value are set by multiplying the first braking force command value by a predetermined ratio, detection is performed. The braking force control when the applied deceleration is incorrect can be set in a more appropriate range.

According to the braking control device of the third aspect of the present invention, when the target deceleration is equal to or higher than the predetermined value, the upper limit value and the lower limit value of the second braking force command value are set to constant values. Therefore, the first braking force command value based on the target deceleration corresponding to the occupant's braking operation amount is mainly used, and the second braking force command value corresponding to the detected deceleration is suppressed to be small. Therefore, the braking force control when the detected deceleration is incorrect can be set in a more appropriate range.

[0011]

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 pedaling force using the high-pressure braking fluid pressure accumulated in the accumulator 22 and boosted by the pump 21, and supplies the boosted pedaling force to the master cylinder. The pump 21 is
Sequence control is performed 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 the braking fluid path, the master cylinder 3 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, which corresponds to a driving wheel, of the wheels 10 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, the regenerative cooperative brake control controller
Brake fluid pressure command value and rotation performed in the control unit 19.
To calculate the raw torque command value, the target deceleration α_demFrom
Braking torque command value T_d-comThe method of calculating
A description will be given based on a clock diagram. For example, the target deceleration α_dem
Is the driver's brake pedal depression amount (braking operation amount),
That is, the master cylinder pressure P_mcIf the value is proportional to
The target deceleration α _demFeed forward only
Feed the term and the deceleration that is actually occurring in the vehicle.
The backed-up feedback term is calculated and the sum of them is calculated.
Braking torque command value T_d-comAnd

In FIG. 2, block B4 (response characteristic P
(s)) corresponds to your vehicle. Α in the figure _VAchieved by own vehicle
It is the deceleration that is performed or occurs. Where the braking open
Deceleration immediately before the start, for example, deceleration due to engine braking force
Deceleration on downhill roads or acceleration on downhill roads
Speed α_BThen, the deceleration α generated in the own vehicle _V
From the reference deceleration α_BThe value obtained by subtracting (α_V-Α_B)But,
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 is made to match the response characteristic P _m (s) of the subject vehicle model to be controlled with the reference model characteristic F _ref (s). The feedforward compensator (phase compensator) C _FF (s) processing shown in the following equation 1 is applied to α _dem to calculate the feedforward term T _d-FF of the braking torque command value. Note that K ₂ in the equation is a vehicle parameter constant for converting the target deceleration α _dem into braking torque.

[0023]

[Equation 1]

On the other hand, in order to calculate the feedback component T _d-FB of the braking torque command value, first in a block B2, with respect to the target deceleration alpha _dem, reference model characteristics F _{re f} (s) the process shown by the two formulas below Then, the reference deceleration α _ref is calculated.

[0025]

[Equation 2]

The reference deceleration α calculated in this way
_{From ref} , the difference (α _V −α _B ) between the deceleration α _V generated in the host vehicle and the reference deceleration α _B is subtracted by the adder / subtractor to calculate the feedback difference value Δα of the deceleration. Then, for the feedback difference value Δα of the deceleration, the block B
In step 3, the feedback compensator C _FB (s) processing shown in the following three equations is applied to the feedback term T _{d-FB of the} braking torque command value.
To calculate. The feedback compensator C _FB (s)
Is a basic PI (proportional-integral) controller, and the control constants K _P and K _I in the equation are set in consideration of the gain margin and the phase margin.

[0027]

[Equation 3]

Therefore, the feedforward term T _d-FF of the braking torque command value and the feedback term T _d-FB of the braking torque command value are added by the adder to add the braking torque command value T.
_d-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 P _mc detected by the master cylinder pressure sensor 11 and each wheel cylinder pressure P _wc detected by the wheel cylinder pressure sensor 12 are output from the braking fluid pressure control unit 13. Read in.

Next, in step S2, the driving wheel speed detected by the driving wheel speed sensor 20 is read as the traveling speed of the vehicle, and the bandpass represented by the transfer function F _bpf (s) of the following four equations is used. The driving wheel deceleration is obtained by performing a filtering process, and is used as the vehicle deceleration α _V generated in the actual vehicle. However, in the equation, ω is a natural angular frequency, and ζ is a damping constant.

[0031]

[Equation 4]

Next, in step S3, the maximum regenerative torque T _mmax available from the motor control unit 18 is read. At the next step S4, multiplied by a predetermined constant K ₁ in the master cylinder pressure P _mc read in the step S1, to calculate the negative value as the target deceleration alpha _dem.

Next, in step S5, an estimated value of deceleration due to the engine braking force and an estimated engine brake deceleration value α _eng 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 T _eng . At the same time, the running resistance T _reg on a flat road is obtained from the running speed of the host vehicle according to the control map of FIG. Then, the sum of them is divided by the average vehicle weight M _V to calculate the engine brake deceleration estimated value α _eng .

Next, in step S6, the target deceleration α _dem calculated in step S4 is subjected to the feedforward compensator (phase compensator) C _FF (s) process of the above equation 1 to apply the braking torque. Feedforward term T of command value
Calculate _d-FF . Next, in step S7, the brake pedal is turned on by using, for example, whether or not the master cylinder pressure P _mc 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, and if it is in the brake pedal on state, the process proceeds to step S9,
If not, the process proceeds to step S8.

In step S8, the brake operation linear deceleration α ₀ and the engine brake deceleration reference value α _eng0 are updated, and then the _{process proceeds} to step S11. In particular,
The braking start time T _J from the accelerator pedal release operation, that is, from the accelerator off to the brake operation, that is, the brake on, is obtained, and the braking start time T _J is, for example, a predetermined value T _J0 or more corresponding to the time when the engine braking force converges. In some cases, the vehicle deceleration α _V calculated in step S2 is set to the deceleration α ₀ immediately before the brake operation, and
The engine brake deceleration estimated value α _eng calculated in 5 is set as the engine brake deceleration reference value α _eng0 . When the braking start time T _J is less than the predetermined value T _J0 , the engine brake deceleration estimated value α _{en g} calculated in step S5 is set as the deceleration α ₀ immediately before the brake operation, and the engine brake deceleration is reduced. The estimated speed value α _eng is set as the engine brake deceleration reference value α _eng0 . That is, when the braking start time T _J is equal to or greater than the predetermined value T _J0 corresponding to the engine brake convergence required time, the actual vehicle deceleration α _{V is set} to the deceleration α ₀ immediately before the braking operation, and when it is less than the predetermined value T _J0 , The engine brake deceleration estimated value α _eng that may occur thereafter is set as the deceleration α ₀ immediately before the brake operation.

On the other hand, in step S9, the engine brake deceleration estimated value α _eng calculated in step S5 is calculated.
_Then , the value _obtained by subtracting the engine brake deceleration reference value α _{eng0 from} is _added to the deceleration α ₀ immediately before the brake operation to calculate the reference deceleration α _B , and then the process proceeds to step S10. In step S10, the reference deceleration α _B calculated in step S9 is used to set the target deceleration α α as described above.
_Reference model characteristic F _ref (s) shown in the above equation 2 with respect to _dem
The reference deceleration rate α _ref is calculated and the difference between the vehicle deceleration rate α _V and the reference deceleration rate α _B (α _V −α _B ) is subtracted from this reference deceleration rate α _ref to obtain the feedback deceleration value of the deceleration rate. Δα is calculated, and the feedback difference value Δα of this deceleration is calculated.
On the other hand, the feedback compensator C _FB (s) shown in the above equation 3
After processing, the feedback term T of the braking torque command value
_After calculating _d-FB , the process proceeds to step S14.

In the step S14, the step S
Whether the master cylinder pressure P _mc read in 1 is less than or equal to a predetermined value P _mc0, that is, the braking operation amount of the occupant, and at the same time, the magnitude of the target deceleration α _dem is more than or equal to a predetermined value. If the master cylinder pressure P _mc is less than or equal to the predetermined value P _mc0 , the _{process proceeds} to step S15, and if not, the process proceeds to step S16.

At the step S15, the step S
The feedforward term T _d-FF of the braking torque command value calculated in 6 is multiplied by the coefficients K _LU and K _LL smaller than “1” to obtain the upper limit value T _d-FBUL of the feedback term of the braking torque command value.
After calculating the lower limit value T _d-FBLL , the _{process proceeds} to step S17. On the other hand, in step S16, the upper limit value T _d-FBUL of the feedback term of the braking torque command value is _set to “0”.
A larger constant C _LU is set, and the lower limit value T _d-FBLL of the feedback term of the braking torque command value is set to a constant C _LL smaller than “0”, and then the _{process proceeds} to step S17.

In the step S17, the step S
15 or the upper limit T _d-FBUL and the lower limit T of the feedback term of the braking torque command value set in step S16.
_{In d-FB-LL} , the feedback term T _{d- FB} of the braking torque command value calculated in step S10 is limited, and then the process proceeds to step S11. In step S11,
The feedforward term T _{d-FF of} the braking torque command value calculated in step S6 and the calculation in step S10,
Alternatively, the braking torque command value _Td-com is obtained from the sum of the braking torque command value restricted in step S17 and the feedback term _Td-FB, and the braking torque command value _{Td -com} is regenerated with the braking fluid pressure braking torque command value _Tb-com. It is distributed to the braking torque command value T _m-com . Here, in order to improve the fuel economy as much as possible, the maximum regenerative torque T _mmax 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 (for example, an ideal braking force distribution map), the braking torque command value T _{d-com is set} to the front wheel braking torque command value T _d-com-F and the rear wheel braking torque command. Value T _d-com-R . Then, the front wheel braking torque command value T
The sum of _d-com-F and the rear wheel braking torque command value T _d-com-R , that is, when the braking torque command value T _d-com is less than the maximum regenerative torque T _mmax , only the regenerative braking is performed, and the front wheel braking is performed. The fluid pressure braking torque command value T _b-com-F and the rear wheel braking fluid pressure braking torque command value T _b-com-R are both set to “0”, and the regenerative braking torque command value T _{m-com is set} to the braking torque command value. T
Set to _d-com . Further, the front wheel braking torque command value T
_{When d-com-F} is _greater than or _{equal to the} maximum regenerative torque T _mmax , regenerative braking and rear wheel braking fluid pressure braking are performed, the front wheel braking fluid pressure braking torque command value T _{b-com-F is set} to "0", and rear wheel braking is performed. The fluid pressure braking torque command value T _b-com-R is _set to a value _obtained by subtracting the maximum regenerative torque T _mmax from the braking torque command value T _d-com , and the regenerative braking torque command value T _{m-com is set} to the maximum regenerative torque T.
Set to _mmax . Further, when the maximum regenerative torque T _mmax is less than or equal to a predetermined value near “0” and the front wheel braking torque command value T _d-com-F is less than the maximum regenerative torque T _mmax , regenerative braking and front and rear wheel braking fluids. Pressure braking is performed, and the front wheel braking fluid pressure braking torque command value T _b-com-F is _set to a value _obtained by subtracting the maximum regenerative torque T _mmax from the front wheel braking torque command value T _{d- com-F} , and the rear wheel braking fluid pressure braking torque. Command value T _b-com-R
Is set as the rear wheel braking torque command value T _d-com-R , and the regenerative braking torque command value T _m-com is set to the maximum regenerative torque T _mmax .
Further, the maximum regenerative torque T _mmax is less than or equal to a predetermined value near “0” and the sum of the front wheel braking torque command value T _d-com-F and the rear wheel braking torque command value T _d-com-R , that is, When the braking torque command value T _d-com is _greater than or _equal to the maximum regenerative torque T _mmax , only the braking fluid pressure braking is performed, and the front wheel braking fluid pressure braking torque command value T _{b-com-F is set} to the front wheel braking torque command value T _{d. -com-F} , rear wheel braking fluid pressure braking torque command value T
_b-com-R is set as the rear wheel braking torque command value T _d-com-R , and the regenerative braking torque command value T _m-com is set to "0".

Next, in step S12, the predetermined vehicle parameter constant K _{3 is} applied to the front and rear wheel braking fluid pressure braking torque command values T _b-com-F and T _b-com-R calculated in step S11.
Multiply by the braking fluid pressure command values for the front and rear wheels P _b-com-F , P
Calculate _b-com-R . Next, in step S13,
Regenerative braking torque command value T calculated in step S11
_While outputting _m-com to the motor control unit 18, the braking fluid pressure command values P _b-com-F and P _{b- com-R} for the front and rear wheels calculated in step S12 are output to the braking fluid pressure control unit. Output to 13 and then return to the main program.

According to this arithmetic processing, the accelerator is turned off.
From the time when the brake is on to the vehicle deceleration at that time
α_VOr engine brake deceleration estimated value α_engThe breaker
Deceleration just before operation α₀As well as the engine at that time
Estimated brake deceleration value α_engEngine brake deceleration
Reference value α_engOWhile updating from time to time, the target deceleration α
_demTorque command value feedforward term T for
_d-FFIs calculated. Braking torque command value T in this state
_d-comIs the braking torque command value feedforward term
T_d-FFSince it is only the
The vehicle deceleration α_VIs reflected in the shift dow
If you press the brake pedal unless you
Since the braking torque command value is smaller than the
Deforward term T_d-FFBraking torque command value T consisting of only
_d-comIs the maximum regenerative torque T_mmaxWhen is less than
Is the front wheel braking fluid pressure braking torque command value T as described above.
_b-com-FAnd the rear wheel braking fluid pressure braking torque command value T
_b-com-RAre both set to “0” and the regenerative braking torque command value T
_m-comIs the braking torque command value T_d-comSet to.

On the other hand, the brake pedal is depressed.
When it is told, the vehicle deceleration α at that time _VOr engine shake
Estimated deceleration rate α_engIs the deceleration α just before the brake operation₀
And the estimated value of engine brake deceleration at that time
α_engIs the engine brake deceleration reference value α_engONoted as
Remember, deceleration α just before this brake operation₀And engine
Brake deceleration reference value α_eng0And use the
Jin brake deceleration estimated value α_engReference deceleration α according to
_BIs calculated, and this reference deceleration α_BAnd the actual vehicle deceleration
α_VAnd the norm deceleration α_refAnd the braking torque command value
Feedback term T_d-FBIs calculated and the braking torque
Command value feed forward term T_d-FFValue is the sum of braking
Torque command value T_d-comBecomes At this time, accelerator off
To brake on time T_JIs the engine breaker
A predetermined value T corresponding to the time when the force converges_J0If it is above,
Vehicle deceleration α at_VIs the deceleration immediately before the brake operation
α ₀Is set to. Therefore, when operating the brake,
Engine braking force, deceleration on uphill roads, and acceleration on downhill roads.
If speed is acting, it is the vehicle deceleration α_VAppear in
Deceleration α immediately before braking₀Is reflected in
Later reference deceleration α_BReflects the effects of those accelerations and decelerations
The standard deceleration rate α_BAnd vehicle deceleration α_VWith
Braking torque command value feedback term T according to the difference
_d-FBReflects only changes in engine braking torque
Value and the amount of brake pedal operation is constant and the braking
Luke command value feed forward term T_d-FFAre equal or
Achieves the driver's intended deceleration as long as they are comparable
be able to.

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 α _eng and the engine brake deceleration reference value α _{eng0 at} that time is used as the reference deceleration. Since it can be reflected in α _B , after that, based on the braking torque command value feedback term T _d-FB corresponding to the difference between the reference deceleration α _B and the vehicle deceleration α _V , the deceleration intended by the driver is reduced. You can continue to achieve speed.

When the time T _J from accelerator off to brake on is less than a predetermined value T _J0 corresponding to the time when the engine braking force converges, the engine brake deceleration estimated value α _{eng is set} to the deceleration immediately before the braking operation. α ₀
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, during constant speed traveling on a flat road, the accelerator is off at time t ₀₁ , the brake is on at time t ₀₂ , and the downshift is performed at time t _03. The master cylinder pressure _Pmc is constant. When the accelerator is turned off at time t ₀₁ , deceleration occurs in the vehicle due to the engine braking force, but the deceleration also gradually decreases as the vehicle traveling speed decreases.

When the brake is turned on at time t ₀₂ , the vehicle deceleration α _{V at} that time is set to the deceleration α ₀ immediately before the braking operation, and the engine brake deceleration estimated value α _{eng at} that time is set to the engine brake deceleration. It is set to the reference value α _eng0 . Therefore, after this time t ₀₂ , the deceleration (α _V −α _B ) corresponding to the depression amount of the brake pedal is added to the deceleration α _B (= α ₀ ) until then, but the vehicle travels thereafter. When the engine brake deceleration estimated value α _eng decreases as the speed decreases, the engine brake deceleration estimated value α _eng and the engine brake deceleration reference value α _eng.
The deceleration reference value α _B is reduced by the difference from _eng0, and the vehicle deceleration α _V generated by the braking fluid pressure control or regenerative braking control is accordingly reduced by the amount by which the engine brake torque is reduced. .

Further, when downshifting is performed at time t ₀₃ ,
The engine brake deceleration estimated value α _eng increases by that _amount, and the deceleration reference value α _B increases by the difference between the engine brake deceleration estimated value α _eng and the engine brake deceleration reference value α _eng0. Accordingly, the vehicle deceleration α _V generated by the braking fluid pressure control or the regenerative braking control is increased by the increase in the engine brake torque. However, even after that, the engine braking force decreases as the traveling speed decreases, so the vehicle deceleration α _V gradually decreases.

FIG. 7 is a simulation of changes in the vehicle deceleration when the regenerative braking torque is rapidly reduced while the braking force control is being performed by the arithmetic processing of FIG. In this embodiment, the deceleration α _V generated in the vehicle
Since the regenerative braking torque and the braking fluid pressure braking torque are controlled while feeding back, the braking fluid pressure braking is performed when the regenerative braking torque is rapidly reduced and the vehicle deceleration α _V is about to be reduced. A rapid increase in torque prevents the vehicle deceleration α _V from decreasing.For example, the deceleration during the transition period when the regenerative braking torque is rapidly decreasing and the steady deceleration after that The value does not change much from the previous value, and the deceleration intended by the driver can be continuously achieved even in such a case.

On the other hand, in FIG. 8, the target deceleration is simply set from the operation amount of the brake pedal, and the braking fluid pressure braking torque is controlled only so that the deceleration of the own vehicle matches the target deceleration. Is. In this case, since the actual vehicle deceleration starts to decrease and the braking fluid pressure braking torque is uniformly increased for the first time, as a result, the deceleration in the transition period in which the regenerative braking torque rapidly decreases is also: The steady deceleration thereafter also changes greatly, and it is difficult to continue to achieve the deceleration intended by the driver.

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, 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. braking torque command value T _d-com of values calculates the sum of the upper limit value T _d-FBUL and the lower limit value T _d-FBLL the feedforward term T _d-FF of the braking torque command value feedback term of the braking torque command value In other words, it is limited by the value. The upper limit of the braking torque command value sum of the upper limit value T _d-FBUL and the lower limit value T _d-FBLL feedforward term T _d-FF and the feedback term of the braking torque command value of the braking torque command value T _{d- comUL} and lower limit T
_{If d-comLL} is set, the upper limit value T of the braking torque command value
_d-comUL and lower limit value T _d-comLL are master cylinder pressure P
_{The mc} is set as shown in FIG.

That is, in a region where the master cylinder pressure P _mc is less than or equal to the predetermined value P _mc0 , the upper limit value T _d-FBUL and the lower limit value T _d-FBLL of the feedback term of the braking torque command value are fed to the braking torque command value. Since the forward term T _d-FF is multiplied by the coefficients K _LU and K _LL , the master cylinder pressure P
_mc , that is, linearly increases with an increase in the feedforward term T _d-FF of the braking torque command value that is the target deceleration. On the other hand, the master cylinder pressure P _mc is the predetermined value P
_In the region of _mc0 or more, the upper limit value T _d-FBUL and the lower limit value T _d-FBLL of the feedback term of the braking torque command value are constant K.
_{Since UL} and K _LL are set, the values are constant regardless of the master cylinder pressure P _mc , that is, the feedforward term T _d-FF of the braking torque command value that is the target deceleration.

FIG. 10 shows the feed back of the braking torque command value.
Upper limit value T_d-FBULAnd the lower limit value T_d-FBLLAlways constant
It is a value. Therefore, the upper limit of the braking torque command value
Value T _{d-com UL}And the lower limit value T_d-comLLIs the braking torque command
Value feedforward term T _d-FFIncrease and decrease with a certain range
To do. Here, time t₀₁Press the brake pedal with
Time t₀₂Even if you keep the depression of the brake pedal constant with
And then at time t₀₃Of road surface projection and road surface friction coefficient
Vehicle deceleration α due to fluctuations_VIs small (numerically large
It is assumed that it was erroneously detected. Also, this time t₀₃Until
Is the vehicle deceleration α _VIs the target deceleration α_demMatches well
As a result, the braking torque command value T_d-comIs almost braking
Luke command value T_d-FFIt was assumed that And time t
₀₃After that, the feedback term T of the braking torque command value
_d-FBBraking torque command value T_{d- com}Is corrected small
However, the lower limit value T of the braking torque command value is_d-comLLBy
Is restricted.

As is apparent from the figure, the upper limit value T _{d-FB UL} and the lower limit value T of the feedback term of the braking torque command value are shown.
_d-FBLL is always a constant value, that is, the constants C _UL and C _LL, and braking is performed so that the vehicle body deceleration α _V matches the target deceleration α _dem in a region where the braking torque command value T _d-com is relatively large. When the allowable range of the feedback term T _d-FB of the torque command value is _expanded, the upper limit value T _d-FBUL and the lower limit value T _d-FBLL of the feedback term of the braking torque command value are _set to relatively large absolute values. There must be. In this simulation, since the vehicle body deceleration α _V was erroneously detected when the braking torque command value T _d-com was relatively large, the braking torque command value T _d-com is the lower limit value T of the appropriate braking torque command value.
_Although limited by _d-comLL , the braking torque command value T
_{If the} vehicle body deceleration α _V is erroneously detected when _d-com is relatively small, the improper upper limit value T _{d-comUL of the} braking torque command value
Alternatively, the lower limit value T _d-comLL is limited, and proper braking force control may not be performed.

FIG. 11 shows that the upper limit value T _d-FBUL and the lower limit value T _d-FBLL of the feedback term of the braking torque command value are always
It is a value obtained by multiplying the feedforward term T _d-FF of the braking torque command value by predetermined coefficients K _UL and K _LL . Therefore, the upper limit value T _d-comUL and the lower limit value T of the braking torque command value are
_d-comLL increases as the feedforward term T _d-FF of the braking torque command value increases. If the vehicle body deceleration α _V is erroneously detected when the braking torque command value T _d-com is relatively small, the braking torque command value T _d-com is the appropriate upper limit value T _{d-comUL of the} braking torque command value. Or the lower limit value T
_Although it is predicted that the braking torque command value T will be limited by _d-comLL , in this simulation, the vehicle body deceleration α _V was erroneously detected when the braking torque command value T _d-com was relatively large. _{Since d-com} is limited by the lower limit value T _d-comLL of the improper braking torque command value, proper braking force control cannot be performed.

In FIG. 12, as in this embodiment, the master cylinder pressure P _mc is equal to or _lower than the predetermined value P _mc0 , that is, the target deceleration α.
_{When dem} is less than or equal to a predetermined value, a value obtained by multiplying the feedforward term T _d-FF of the braking torque command value by predetermined coefficients K _UL and K _LL is the upper limit value T of the feedback term of the braking torque command value.
_{With d-FBUL} and lower limit value T _d-FBLL , master cylinder pressure P _mc
There predetermined value P _mc0 above, that is, when the target deceleration alpha _dem is above a predetermined value, the constant C _UL, and the upper limit value T _d-FBUL and the lower limit value T _{d- FBLL} feedback terms of C _LL braking torque command value It is a thing. With such a setting, for example, in a region where the braking torque command value T _d-com is relatively large, the vehicle body deceleration α
_In order to make _V equal to the target deceleration α _dem , the upper limit value T of the feedback term of the braking torque command value is increased in order to widen the allowable range of the feedback term T _d-FB of the braking torque command value.
_{Even if the d-FBUL} and the lower limit value T _d-FBLL have relatively large absolute values, when the braking torque command value T _d-com is relatively small, the feedforward term T _d-FF of the braking torque command value.
Accordingly, the upper limit value T _d-FBUL and the lower limit value T _d-FBLL of the feedback term of the braking torque command value become relatively small absolute values. In this simulation, the vehicle body deceleration α _V is erroneously detected when the braking torque command value T _d-com is relatively large, and the braking torque command value T _d-com is the lower limit value T _{d- of the} appropriate braking torque command value. _Although limited by _comLL , even if the vehicle body deceleration α _V is erroneously detected when the braking torque command value T _d-com is relatively small, the appropriate upper limit value T _d-comUL or the lower limit of the braking torque command value is set. It is limited by the value T _d-comLL , and proper braking force control can be continuously executed.

From the above, step S4 of the arithmetic processing of FIG. 3 constitutes the target deceleration setting means of the present invention, and the driving wheel speed sensor 20 and step S2 of the arithmetic processing of FIG. 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 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 a timing chart showing changes in braking torque and vehicle deceleration due to the arithmetic processing of FIG.

FIG. 8 is a timing chart showing changes in braking torque and vehicle deceleration due to conventional braking force control.

9 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. 10 is an explanatory diagram of a braking torque command value when a vehicle body deceleration is erroneously detected.

FIG. 11 is an explanatory diagram of a braking torque command value when a vehicle body deceleration is erroneously detected.

12 is an explanatory diagram of a braking torque command value when a vehicle body deceleration is erroneously detected by 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

   ─────────────────────────────────────────────────── ─── 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 AA09 BB01 BB31 CC02 CC06                       EE01 HH02 HH05 HH16 HH26                       HH36 JJ03 JJ04 LL00 MM13                 5H115 PA08 PC06 PG04 PI16 PI24                       PO02 PO06 PO09 PO17 PU10                       PU11 PU23 PU25 PV09 QI04                       QI07 QI09 QI15 QN03 QN04                       QN11 QN15 QN22 QN23 QN24                       QN27 RB22 SE04 SE05 SE06                       SE10 TB03 TI01 TI10 TO02                       TO23 TO26

Claims (3)

[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 command value upper and lower limit value setting means for setting an upper limit value and a lower limit value of a braking force command value to the braking means based on the target deceleration set by the target deceleration setting means,
The braking force command value is set based on the deceleration detected by the deceleration detecting means and the target deceleration set by the target deceleration setting means while the occupant is braking, and the upper and lower limits of the braking force command value are set. Braking control means for controlling the braking force applied to each wheel by the braking means on the basis of the braking force command values limited by the upper limit value and the lower limit value of the braking force command value set by the value setting means. Braking control device. 2. The braking control means responds to a first braking force command value according to the target deceleration set by the target deceleration setting means and a deceleration detected by the deceleration detection means. The braking force command value is calculated from the addition value with the second braking force command value, and the braking command value upper and lower limit value setting means multiplies the first braking force command value by a predetermined ratio to obtain a second braking force command value. The braking control device according to claim 1, wherein the upper limit value and the lower limit value of the braking force command value are set to set the upper limit value and the lower limit value of the braking force command value. 3. The braking command value upper and lower limit value setting means, when the target deceleration set by the target deceleration setting means is a predetermined value or more, an upper limit value of the second braking force command value and The braking control device according to claim 2, wherein the lower limit value is a constant value.