JP5316171B2 - Braking force control device for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a braking force control device for a vehicle and a braking force control method for a vehicle which can smoothly shift to lateral acceleration by suppressing the variation of longitudinal acceleration when actuating automatic braking during easing-up on a brake pedal by a driver. <P>SOLUTION: A final target deceleration setting part 27 makes a reducing ratio of the final target deceleration xg* smaller than driver request deceleration xg_dr* when the driver request deceleration xg_dr* is bigger than deceleration xg0* for control if CBA is actuated during the easing-up operation of a brake pedal by a driver. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention belongs to the technical field of a vehicle braking force control device and a vehicle braking force control method.

  In Patent Document 1, when automatic braking is activated in a state where the driver is operating the brake, a final selection is made by selecting high between the driver requested deceleration corresponding to the brake operation and the control deceleration that is the target deceleration of the automatic braking. A technique for determining a target deceleration is disclosed.

  Further, in Patent Document 1, in determining the final target deceleration, the increase rate of the driver required deceleration is reflected in the final target deceleration even when the driver required deceleration is smaller than the control deceleration. Therefore, the deceleration of the vehicle is matched with the driver's intention to increase the deceleration.

JP 2005-343397 A

  However, in the above prior art, when the automatic braking is activated when the driver enters the curve while releasing the brake immediately before the curve, the lateral acceleration occurs after the deceleration of the vehicle is lost. That is, since the longitudinal acceleration changes greatly before the lateral acceleration occurs, there is a problem in that the driver is not connected smoothly from the longitudinal acceleration to the lateral acceleration, and the driver feels uncomfortable.

  The present invention has been made paying attention to the above-mentioned problem, and the object of the present invention is to suppress the fluctuation of the longitudinal acceleration when the automatic braking is activated during the driver's brake pedal depressing operation, and to achieve the lateral acceleration. An object of the present invention is to provide a vehicle braking force control device and a vehicle braking force control method that can be smoothly connected.

In order to achieve the above-mentioned object, in the present invention, when automatic braking is activated during the driver's brake pedal depressing operation, when the driver-requested deceleration is larger than the control deceleration , the final target deceleration reduction rate is set. Decrease the driver's required deceleration.

  Therefore, in this invention, the fluctuation | variation of the longitudinal acceleration when automatic braking act | operates during a driver | operator's brake pedal stepping-back operation can be suppressed, and it can connect smoothly to a lateral acceleration.

1 is a block diagram illustrating a vehicle braking system to which a vehicle braking force control apparatus according to a first embodiment is applied. FIG. 3 is a control block diagram of CBA in the brake control unit 1 according to the first embodiment. It is a figure which shows the relationship between the deceleration xg0 ^* for control of Example 1, and the deceleration flag fcop for control. FIG. 6 is a diagram illustrating a relationship between a control deceleration xg0 ^* and a control deceleration flag fcop when the control deceleration xg0 ^{* according} to the first embodiment is filtered. 7 is a flowchart illustrating a flow of driver request deceleration calculation processing executed by a driver request deceleration calculation unit according to the first embodiment. FIG. 6 is a setting map of a predetermined value brkdn_dr corresponding to a deviation between a driver requested deceleration xg_dr ^* and a control deceleration xg0 ^* according to the first embodiment. FIG. 10 is a setting map of a predetermined value brkdn_dr corresponding to the driver request deceleration xg_dr ^* of the first embodiment. 6 is a setting map of a predetermined value brkdn_dr corresponding to the lateral acceleration Yg of the first embodiment. 7 is a flowchart illustrating a flow of final target deceleration setting processing executed by a final target deceleration setting unit 27 according to the first embodiment. It is a schematic diagram which shows a state when CBA act | operates in the state which the driver is brake-operating at the time of a curve approach. It is a time chart of the conventional final target deceleration. 3 is a time chart of a final target deceleration according to the first embodiment. It is a figure which shows the acceleration change which acts on the vehicle of Example 1. FIG. FIG. 10 is a setting map of a master pressure sensitive correction amount Yg_mc corresponding to a master cylinder pressure Pmc of Example 3. FIG. FIG. 10 is a setting map of a predetermined value brkdn_dr corresponding to the accelerator opening APO of Embodiment 3. FIG. It is a time chart of final target deceleration when CBA act | operates in the state which the driver | operator is brake-operating at the time of the curve approach of Example 3. FIG. FIG. 10 is a setting map of a predetermined value brkdn_dr corresponding to a deviation between a driver requested deceleration xg_dr ^* and a control deceleration xg0 ^* according to a fourth embodiment. It is a time chart of final target deceleration when CBA act | operates in the state where the driver is brake-operating at the time of the curve approach of Example 4.

  Hereinafter, modes for carrying out the present invention will be described based on examples.

FIG. 1 is a block diagram illustrating a vehicle braking system to which the vehicle braking force control apparatus according to the first embodiment is applied.
The brake control unit 1 acquires information from a wheel speed sensor 2, a steering angle sensor 3, an accelerator switch 4, a brake stroke sensor 5, a yaw rate sensor 6, and an acceleration sensor (lateral acceleration detection means) 7.

The wheel speed sensor 2 detects the rotation speed of each wheel FL, FR, RL, RR as the wheel speed vFL, vFR, vRL, vRR.
The steering angle sensor 3 detects a steering angle θ that is an operation amount of the handle 8.
The accelerator switch 4 detects the presence or absence of an accelerator operation by the driver. The accelerator switch 4 outputs an ON signal when the accelerator pedal 9 is operated, and outputs an OFF signal when it is not operated.
The brake stroke sensor 5 detects an operation amount of the brake pedal 10 as a brake pedal stroke amount BS.

The yaw rate sensor 6 detects a yaw rate ψ acting on the center of gravity of the vehicle.
The acceleration sensor 7 detects the longitudinal acceleration (longitudinal acceleration) Xg and the lateral acceleration (lateral acceleration) Yg of the vehicle, respectively.

The brake control unit 1 executes automatic braking control, which will be described later, based on information from each sensor and outputs a braking command to the hydraulic pressure control unit 12, thereby controlling the wheels FL, FR, RL, RR. Control power.
The hydraulic pressure control unit 12 supplies hydraulic pressure to the wheel cylinders 11FL, 11FR, 11RL, and 11RR in response to a braking command from the brake control unit 1.
Here, in the first embodiment, as the automatic braking, the lateral acceleration at which the turning behavior during curve traveling is stabilized is set to the upper limit value (control lateral acceleration), and the automatic braking is performed so as not to exceed the control lateral acceleration. Execute curve brake assist (hereinafter referred to as CBA).

  FIG. 2 is a control block diagram of CBA in the brake control unit 1 according to the first embodiment. The brake control unit 1 includes a yaw rate calculation unit 21, a road surface μ estimation unit 22, a lateral acceleration limit value calculation unit 23, and a control. Vehicle speed calculation unit 24, control deceleration calculation unit (control deceleration calculation unit) 25, driver request deceleration calculation unit (driver request deceleration calculation unit) 26, and final target deceleration setting unit (final target deceleration) A deceleration setting means) 27, and a braking force control unit (braking force control means) 28.

The yaw rate calculation unit 21 is based on the steering angle θ detected by the steering angle sensor 3 and the vehicle speed (vehicle speed) v obtained from the wheel speeds vFL, vFR, vRL, vRR detected by the wheel speed sensors 2. The yaw rate acting on the vehicle (estimated yaw rate ψ ^) is estimated. The estimated yaw rate ψ ^ and the detected yaw rate ψ detected by the yaw rate sensor 6 are compared with each other in absolute value, and the yaw rate select value ψ ^* is output to the control vehicle speed calculation unit 24 by select high.

  The road surface μ estimation unit 22 estimates the road surface μ estimated value μ and outputs it to the control vehicle speed calculation unit 24. The estimation method of the road surface μ is well known. For example, the slip ratio S is calculated from the calculated vehicle speed v and the wheel speed of the driving wheel (for example, the average value of vRL and vRR in the case of an FR vehicle). Accordingly, a method for estimating the road surface μ can be used.

The lateral acceleration limit value calculation unit 23 uses the control lateral acceleration Yg_a, which is the target lateral acceleration of the CBA set to a predetermined value (for example, 0.55 G), as the lateral acceleration limit value Yg ^* , and the control vehicle speed calculation unit 24. Output to. Here, the predetermined value 0.55G is a lateral acceleration that can be stably turned without a brake, and varies depending on the specifications of the vehicle.

The control vehicle speed calculation unit 24 is estimated by the yaw rate selection value ψ ^* calculated by the yaw rate calculation unit 21, the lateral acceleration limit value Yg ^* calculated by the lateral acceleration limit value calculation unit 23, and the road surface μ estimation unit 22. Based on the estimated road surface μ, the CBA control vehicle speed v ^* is calculated and output to the control deceleration calculation unit 25. The control vehicle speed v ^* is calculated from the following equation.
v ^* = (μ × Yg ^* ) / ψ

The control deceleration calculation unit 25 calculates a control deceleration xg0 ^* from the control vehicle speed v ^* calculated by the control vehicle speed calculation unit with reference to the following equation, and sends it to the final target deceleration setting unit 27. Output.
xg0 ^* = (K × Δv) / Δt
Here, Δv is a deviation (speed deviation) between the vehicle speed v and the control vehicle speed v ^* , Δt is a predetermined time (time until the speed deviation Δv is zero), and K is a predetermined gain.
A value obtained by filtering the control deceleration xg0 ^* with a low-pass filter or the like may be used as the final control deceleration value.

When the control deceleration xg0 ^* > 0, the control deceleration calculation unit 25 outputs a control deceleration flag fcop = ON indicating that the CBA is operating to the driver required deceleration calculation unit 26, and the control deceleration calculation When the speed xg0 ^* = 0, a control deceleration flag fcop = OFF indicating CBA non-operation is output (see FIG. 3). At this time, when the control deceleration xg0 ^* is filtered by a low-pass filter or the like, as shown in FIG. 4, the control deceleration flag = fcop is slightly delayed after the control deceleration xg0 ^* becomes zero. = OFF.

The driver request deceleration calculation unit 26 calculates a driver request deceleration xg_dr ^* corresponding to the brake stroke amount BS detected by the brake stroke sensor 5, and outputs it to the final target deceleration setting unit 27. Driver request deceleration calculating unit 26, when CBA operation, the driver requests deceleration Xg_dr ^*, the deviation between the driver request deceleration Xg_dr ^* and the control deceleration Xg0 ^*, lateral acceleration Yg, the driver requests a decrease in response to the accelerator switch signal Correct the speed xg_dr ^* .

Final target deceleration setting unit 27, the driver and the required deceleration calculation unit driver request deceleration calculated by 26 xg_dr ^*, select-high value has been the control deceleration Xg0 ^* calculated by the control deceleration calculation unit 25 Is set as the final target deceleration xg ^* and output to the braking force control unit 28. Here, the final target deceleration setting unit 27, when the CBA in operation depression return the brake pedal of the driver is actuated, when the driver requests deceleration Xg_dr ^* greater than control deceleration Xg0 ^*, the final target deceleration xg ^* the reduction rate is smaller than the driver demand deceleration Xg_dr ^* reduction rate of.

The final target deceleration setting unit 27 immediately after the brake pedal is returned and when the accelerator operation is performed while the CBA is continued, the reduction rate of the final target deceleration xg ^* is decreased by the control deceleration xg0 ^* . Greater than rate.
The braking force control unit 28 outputs a braking command for obtaining the final target deceleration xg ^* calculated by the final target deceleration setting unit 27 to the hydraulic control unit 12, and each wheel cylinder 11FL, 11FR, 11RL, 11RR. Adjust the wheel cylinder pressure.

[Driver demand deceleration calculation processing]
FIG. 5 is a flowchart showing the flow of the driver request deceleration calculation process executed by the driver request deceleration calculation unit 26 according to the first embodiment. Each step will be described below. This control process is repeatedly executed at a predetermined calculation cycle.
In step S1, it is determined whether or not the control deceleration flag fcop is ON. If YES, the process proceeds to step S2, and if NO, the process proceeds to step S3. Here, the control deceleration flag fcop determines whether the CBA is in operation or not, and is ON when the CBA is operating, and is OFF when the CBA is not operating.

In step S2, the driver deceleration flag fcopdr is turned on, and the process proceeds to step S4. Here, the driver deceleration flag fcopdr is a flag indicating that the driver is operating (depressing) the brake pedal.
In step S3, it is determined whether or not the driver deceleration flag fcopdr is ON. If YES, the process proceeds to step S9. If NO, the process proceeds to step S14.

In step S4, the difference between the current value xg_dr of the driver request deceleration and the previous value xg_drz1 ^* is determined from the predetermined value brkdn_dr as to whether or not the change gradient of the driver request deceleration is smaller than a predetermined value (predetermined gradient) Is also determined by whether it is small or not. If YES, the process proceeds to step S5. If NO, the process proceeds to step S6.
Here, the predetermined value brkdn_dr is changed according to the driver requested deceleration xg_dr ^* , the deviation between the driver requested deceleration xg_dr ^* and the control deceleration xg0 ^* , the lateral acceleration Yg, and the accelerator switch signal.
FIG. 6 is a setting map of the predetermined value brkdn_dr corresponding to the deviation between the driver requested deceleration xg_dr ^* and the control deceleration xg0 ^* , and the predetermined value brkdn_dr is set to be a larger value as the deviation is larger. .

Figure 7 is a setting map of a predetermined value brkdn_dr in response to driver demand deceleration Xg_dr ^*, predetermined value brkdn_dr the driver requests deceleration Xg_dr ^* is CBA maximum deceleration (e.g., 0.25 G) if it is below a certain If a value is taken and the CBA maximum deceleration is exceeded, the larger the driver requested deceleration xg_dr ^* , the larger the setting.
FIG. 8 is a setting map of the predetermined value brkdn_dr corresponding to the lateral acceleration Yg. The predetermined value brkdn_dr takes a constant value when the lateral acceleration is equal to or less than the lateral acceleration limit value Yg ^* , and the lateral acceleration is the lateral acceleration limit value. When Yg ^* is exceeded, the value is set to be smaller as the lateral acceleration is larger.

In step S5, a predetermined value brkdn_dr is subtracted from the previous value xg_drz1 ^{* of} the driver request deceleration to calculate a driver request deceleration final value xg_dr ^*, and the process proceeds to step S7.
Xg_dr ^* = xg_drz1 ^* − brkdn_dr
In step S6, the driver request deceleration xg_dr is set as the driver request deceleration final value xg_dr ^*, and the process proceeds to step S14.
Xg_dr ^* = xg_dr

In step S7, it is determined whether or not the driver requested deceleration final value xg_dr ^* is negative (<0). If YES, the process proceeds to step S8, and if NO, the process proceeds to step S14.
In step S8, the driver requested deceleration final value xg_dr ^{* is set} to zero and the driver deceleration flag fcopdr = OFF, and the process proceeds to step S14.
In step S9, whether or not the change slope of the driver requested deceleration is smaller than a predetermined value (predetermined slope) brkdn_dr, the difference between the current value xg_dr of the driver requested deceleration and the previous value xg_drz1 ^* is greater than the predetermined value brkdn_dr. Is also determined by whether it is small or not. If YES, the process proceeds to step S10, and if NO, the process proceeds to step S11.
In step S10, the driver requested deceleration final value xg_dr ^* is calculated by subtracting the predetermined value brkdn_dr from the previous value xg_drz1 ^* of the driver requested deceleration, and the process proceeds to step S12.
Xg_dr ^* = xg_drz1 ^* − brkdn_dr

In step S11, the driver request deceleration xg_dr is set to the driver request deceleration final value xg_dr ^*, and the process proceeds to step S14.
Xg_dr ^* = xg_dr
In step S12, it is determined whether or not the driver requested deceleration final value xg_dr ^* is negative (<0). If YES, the process proceeds to step S13. If NO, the process proceeds to step S14.
In step S13, the driver requested deceleration final value xg_dr ^{* is set} to zero and the driver deceleration flag fcopdr = OFF, and the process proceeds to step S14.
In step S14, the previous value of the driver request deceleration is updated, and the process proceeds to return.
xg_drz1 ^* = xg_dr ^*

[Final target deceleration setting process]
FIG. 9 is a flowchart illustrating the flow of the final target deceleration setting process executed by the final target deceleration setting unit 27 according to the first embodiment. This control process is repeatedly executed at a predetermined calculation cycle.
In step S21, the selected high value of the driver requested deceleration xg_dr ^* and the control deceleration xg0 ^* is set as the final target deceleration xg ^*, and the process proceeds to return.
Xg ^* = max (xg_dr ^* , xg0 ^* )

Next, the operation will be described.
[Acceleration change suppression effect]
FIG. 10 is a schematic diagram showing a state when the CBA is activated with the driver operating the brake when entering the curve, and FIG. 11 is a time chart of the final target deceleration at this time.
The driver starts depressing the brake pedal at time t01, and the vehicle gradually decelerates. Since the lateral acceleration of the vehicle exceeds the lateral acceleration limit value Yg ^* at time t02, the CBA is activated. At this time, the final target deceleration is determined by the selection high of the driver requested deceleration according to the driver's brake operation and the CBA control deceleration, but in the conventional vehicle braking force control device, the driver deceleration In order to reflect the intention on the vehicle deceleration, the final target deceleration reduction rate is set according to the driver requested deceleration reduction rate even if the driver requested deceleration is smaller than the control deceleration. ing.

Therefore, in the conventional vehicle braking force control device, when the final target deceleration is switched from the driver requested deceleration to the CBA control deceleration at time t03, the deceleration acting on the vehicle once decreases and then increases again. As a result, the acceleration acting on the vehicle is not smoothly connected from the longitudinal acceleration to the lateral acceleration, which gives the driver an uncomfortable feeling.
In contrast, in the vehicle brake force control apparatus of the first embodiment, if the CBA in operation depression return the brake pedal of the driver is actuated, when the driver requests deceleration Xg_dr ^* greater than control deceleration Xg0 ^* the final The reduction rate of the target deceleration xg ^* is made smaller than the reduction rate of the driver requested deceleration xg_dr ^* .

FIG. 12 is a time chart of the final target deceleration of the first embodiment. At time t1, the driver starts to depress the brake pedal. Therefore, in the flowchart of FIG. 5, go to step S1, step S3, step S11, and step S14. It will be a flow that goes forward. Therefore, the final target deceleration xg ^* is the driver requested deceleration xg_dr.
At time t2, due to a CBA flag fcop = ON by the operation of the CBA, the process proceeds to step S1 → step S2 → step S4, In step S4, the driver demand deceleration change gradient (xg_dr - xg_drz1 ^*) and a predetermined gradient brkdn_dr And compare. YES determination at step S4, i.e., the predetermined If the driver requests deceleration Xg_dr reduction rate is large, the process proceeds to step S5, the decreasing gradient of the driver request deceleration Xg_dr ^*, obtained by subtracting a predetermined gradient brkdn_dr from the previous value Xg_drz1 ^* The gradient. Therefore, the final target deceleration xg ^* to become the driver requests deceleration final value Gx_dr ^* is a value larger than the driver required deceleration Gx_dr.

For this reason, in a scene where control deceleration xg0 ^* is required due to CBA intervention during turning, even if the driver suddenly steps back on the brake, the final target deceleration xg ^* is obtained from the driver requested deceleration xg_dr. Also, the acceleration fluctuations acting on the vehicle can be suppressed to a low level by reducing the speed gently.
At time t3, the control deceleration xg0 ^* exceeds the driver requested deceleration xg_dr ^* , so the final target deceleration xg ^* is switched from the driver requested deceleration final value xg_dr ^* to the control deceleration xg0 ^*. in, in a period from time point t2 to time point t3, since the final target deceleration xg ^* slowly reduced than the driver demand deceleration Xg_dr, smooth to the driver requested deceleration Xg_dr ^* control deceleration from Xg0 ^* The fluctuation of the longitudinal acceleration can be suppressed.

  FIG. 13 is a diagram illustrating a change in acceleration acting on the vehicle according to the first embodiment. In the conventional vehicle braking force control apparatus, when the acceleration acting on the vehicle shifts from the longitudinal acceleration to the lateral acceleration, the acting on the vehicle is illustrated. When the acceleration to be performed once decreases and then increases again, the driver feels uncomfortable. On the other hand, in Example 1, the fluctuation | variation of the acceleration which acts on a vehicle is suppressed, and it turns out that it is connected smoothly from the longitudinal acceleration to the lateral acceleration.

Next, the effect will be described.
The vehicle braking force control apparatus according to the first embodiment has the following effects.

(1) When CBA is activated during the driver's brake pedal depressing operation, if the driver requested deceleration xg_dr ^* is greater than the control deceleration xg0 ^* , the final target deceleration xg ^* rate of decrease is calculated as the driver requested deceleration. Make it smaller than xg_dr ^* . Thus, it is possible to smoothly connect to the lateral acceleration by suppressing the fluctuation of the longitudinal acceleration when the CBA is activated during the driver's brake pedal depressing operation.

(2) The predetermined gradient brkdn_dr that determines the decreasing gradient of the final target deceleration xg ^* is increased as the deviation between the driver requested deceleration xg_dr ^* and the control deceleration xg0 ^* increases. In other words, the smaller the deviation between the driver requested deceleration xg_dr ^* and the control deceleration xg0 ^* , the smaller the difference, so the driver requested deceleration xg_dr ^* and the control deceleration xg0 ^* can be connected smoothly. , Fluctuations in the longitudinal acceleration can be reduced.

(3) The predetermined gradient brkdn_dr that determines the decreasing gradient of the final target deceleration xg ^* is increased as the driver requested deceleration xg_dr ^* is increased. When the driver required deceleration xg_dr ^* is large, the slope becomes steep, so in a region where the longitudinal acceleration is high, the driver's intention to return the brake can be reflected in the vehicle deceleration, while the longitudinal acceleration is low. In the area, the longitudinal acceleration can be smoothly connected.

(4) Since the predetermined gradient brkdn_dr that determines the decreasing gradient of the final target deceleration xg ^* is made smaller as the lateral acceleration Yg is larger, fluctuations in the final target deceleration xg ^* are suppressed in a region where the lateral acceleration is high. Can do.

(5) Immediately after returning the brake pedal, if the accelerator is operated while the CBA is continued, the driver will set the final target deceleration xg ^* reduction rate larger than the control deceleration xg0 ^* reduction rate. Can be reflected in the deceleration of the vehicle.

(6) The final target deceleration xg ^* is calculated based on the driver requested deceleration xg_dr ^* corresponding to the driver's brake operation and the control deceleration xg0 ^* which is the target value of the CBA that automatically brakes the vehicle according to the driving condition. In the vehicle braking force control method that sets and controls the braking force of the vehicle according to this final target deceleration xg ^* , if the CBA is activated during the driver's brake pedal depressing operation, the driver requested deceleration xg_dr ^* is When it is larger than the control deceleration xg0 ^* , the decrease rate of the final target deceleration xg ^* is made smaller than the decrease rate of the driver request deceleration xg_dr ^* . Thus, it is possible to smoothly connect to the lateral acceleration by suppressing the fluctuation of the longitudinal acceleration when the CBA is activated during the driver's brake pedal depressing operation.

  In the second embodiment, only the final target deceleration setting method is different from the first embodiment, and the other configurations are the same as those in the first embodiment.

In the final target deceleration setting unit 27 of the second embodiment, after setting the final target deceleration xg ^* , if the deviation between the driver requested deceleration xg_dr ^* and the control deceleration xg0 ^* changes by a predetermined value, Set the target deceleration xg ^* . Predetermined value, for example, a predetermined value brkdn_dr of Example 1, the deviation between the driver request deceleration Xg_dr ^* and the control deceleration Xg0 ^*, driver demand deceleration Xg_dr ^* size, and in accordance with the lateral acceleration Yg change You may let them.

  The hydraulic pressure control unit 12 includes a pump, an electric motor that drives the pump, and a plurality of solenoid valves. Each component is driven in accordance with a braking command from the brake control unit 1. Here, when the frequency of braking commands from the brake control unit 1 is high, the operation frequency of the pump, the motor, and each solenoid valve increases, which may lead to deterioration in durability.

Therefore, in the second embodiment, the final target deceleration xg ^* is set every time the deviation between the driver requested deceleration xg_dr ^* and the control deceleration xg0 ^* changes by a predetermined value, and a braking command is output to the hydraulic pressure control unit 12 By doing so, it is possible to suppress the variation in the longitudinal acceleration and smoothly connect the longitudinal acceleration to the lateral acceleration, while suppressing the operation frequency of the hydraulic pressure control unit 12 and improving the durability.

Next, the effect will be described.
The vehicle braking force control apparatus according to the second embodiment has the following effects in addition to the effects (1) to (6) of the first embodiment.
(7) When the deviation between the driver required deceleration xg_dr ^* and the control deceleration xg0 ^* changes by a predetermined value, the next final target deceleration xg ^* is set, so that the durability of the hydraulic control unit 12 is improved. be able to.

The third embodiment is an example in which the CBA intervention timing is advanced when the driver is operating the brake compared to when the driver is not operating the brake. Note that the description of the same configuration as that of the first embodiment is omitted.
The lateral acceleration limit value calculation unit (operation start timing changing means) 23 calculates the lateral acceleration limit value Yg ^* by adding the control lateral acceleration Yg_a (for example, 0.55G) and the master pressure sensitive correction amount Yg_mc.
Yg ^* = Yg_a + Yg_mc

  FIG. 14 is a setting map of the master pressure sensitive correction amount Yg_mc corresponding to the master cylinder pressure Pmc. The master pressure sensitive correction amount Yg_mc is decreased as the master cylinder pressure Pmc is larger when the master cylinder pressure Pmc is equal to or lower than the predetermined pressure Pmc1. When the master cylinder pressure Pmc exceeds the predetermined pressure Pmc1, a certain minimum value (for example, -0.1G) is set. Here, the predetermined value Pmc1 is a value that takes into account the drift of a master cylinder pressure sensor (not shown) that detects the master cylinder pressure Pmc.

The driver request deceleration calculation unit 26 calculates a driver request deceleration xg_dr ^* corresponding to the brake stroke amount BS detected by the brake stroke sensor 5 regardless of the operation or non-operation of the CBA, and a final target deceleration setting unit. To 27.
Final target deceleration setting unit 27, the driver and the required deceleration calculation unit driver request deceleration calculated by 26 xg_dr ^*, select-high value has been the control deceleration Xg0 ^* calculated by the control deceleration calculation unit 25 Is set as the final target deceleration xg ^* and output to the braking force control unit 28.

In the third embodiment, when the driver performs an accelerator operation during the execution of CBA, the predetermined gradient brkdn_dr that determines the decreasing gradient of the final target deceleration xg ^* is changed according to the accelerator opening APO. FIG. 15 is a setting map of the predetermined value brkdn_dr corresponding to the accelerator opening APO, and the predetermined value brkdn_dr is larger as the accelerator opening APO is higher in the range from the accelerator opening APO to zero to the predetermined value APO1. When the accelerator opening APO exceeds a predetermined value APO1, it is set to take a certain maximum value.

Next, the operation will be described.
[Acceleration change suppression effect]
FIG. 16 is a time chart of the final target deceleration when the CBA is activated with the driver operating the brake when entering the curve.
The driver starts depressing the brake pedal at time t01, and the vehicle gradually decelerates. Since the lateral acceleration of the vehicle exceeds the lateral acceleration limit value Yg ^* at time t02 ′, the CBA is activated. Here, in the conventional vehicle braking force control apparatus, the lateral acceleration limit value Yg ^* is set to a constant value (for example, 0.55 G), and therefore the operation start timing of the CBA is a time point t02. Therefore, when the final target deceleration Xg_dr ^* is switched to the driver demand deceleration Xg_dr ^* control deceleration from Xg0 ^*, large acceleration variation .DELTA.G ₀ in the longitudinal direction of the vehicle is generated.

On the other hand, in the vehicle braking force control apparatus according to the third embodiment, when the driver is depressing the brake pedal, the lateral acceleration limit value Yg ^* is made smaller than the control lateral acceleration Yg_a (for example, 0.55G). . Therefore, compared with the case where the driver does not depress the brake pedal, the control vehicle speed V ^* becomes smaller, so CBA can be started at an earlier timing (t02 ′ <t02). Therefore, the acceleration fluctuation ΔG when the final target deceleration xg_dr ^* is switched from the driver requested deceleration xg_dr ^* to the control deceleration xg0 ^* can be reduced.

In the third embodiment, the master pressure sensitivity correction amount Yg_mc for correcting the lateral acceleration limit value Yg ^* is decreased as the master cylinder pressure Pmc is increased, so that the driver is not stepping on the brake pedal and is slightly stepping on the brake pedal. It is possible to prevent the occurrence of control hunting due to the fluctuation of the lateral acceleration limit value Yg ^* between and. Moreover, malfunction of CBA due to sensor drift or the like can be suppressed.
Further, in the third embodiment, as the accelerator opening APO is higher, the predetermined gradient brkdn_dr that determines the decreasing gradient of the final target deceleration xg ^* is increased. That is, when the driver steps on the accelerator, acceleration failure can be suppressed by giving priority to the driver's intention to accelerate.

Next, the effect will be described.
The vehicle braking force control apparatus according to the third embodiment has the following effects in addition to the effects (1) and (5) of the first embodiment.
(8) When the driver's brake pedal depressing operation is in progress, in order to speed up the CBA operation start timing, the change in longitudinal acceleration when the CBA is activated during the driver's brake pedal depressing operation is suppressed to the lateral acceleration. Can be connected smoothly.

  (9) The smaller the required driver deceleration, the smaller the amount to advance the CBA operation start timing, so that control hunting can be prevented. Moreover, malfunction of CBA due to sensor drift or the like can be suppressed.

(10) When the driver performs the accelerator operation while the automatic braking is continued, the acceleration when the driver requests acceleration to increase the decrease rate of the final target deceleration xg_dr ^* as the accelerator operation amount increases. Defects can be suppressed.

Example 4 is an example in which Example 1 and Example 3 are combined. In other words, when the driver is performing the brake operation, the predetermined gradient brkdn_dr that determines the decrease gradient of the final target deceleration xg ^* is set to the driver requested deceleration xg_dr while the CBA intervention timing is advanced earlier than when the brake operation is not performed. ^The greater the deviation between ^* and control deceleration xg0 ^* , the greater the difference.

FIG. 17 is a setting map of the predetermined value brkdn_dr corresponding to the deviation between the driver requested deceleration xg_dr ^* and the control deceleration xg0 ^{*. In the} fourth embodiment, as the deviation increases, the predetermined value increases as the deviation increases. Although brkdn_dr is set to a large value, the predetermined value brkdn_dr corresponding to the deviation is set to be larger than in the case of the first embodiment.
Here, as a method of increasing the predetermined value brkdn_dr corresponding to the deviation, as shown in FIG. 17, with respect to the characteristics of the first embodiment, (a) a method of increasing the value of the predetermined value brkdn_dr when the deviation is zero (B) a method of increasing the maximum value of the predetermined value brkdn_dr, (c) a method of increasing the value of the predetermined value brkdn_dr when the deviation is zero, and a method of decreasing the deviation value taking the maximum value, (d) a predetermined value Examples include a method of increasing the maximum value of the value brkdn_dr and increasing the value of the deviation that takes the maximum value, and (e) a method of reducing the value of the deviation that takes the maximum value.

Next, the operation will be described.
FIG. 18 is a time chart of the final target deceleration when the CBA is activated with the driver operating the brake when entering the curve.
In the fourth embodiment, in addition to the control for making the predetermined gradient brkdn_dr that determines the decreasing gradient of the final target deceleration xg ^* smaller than the driver requested deceleration xg_dr ^* , the control for advancing the CBA operation start timing is performed. For this reason, when the predetermined gradient brkdn_dr is set to be equivalent to that of the first embodiment, it takes time until the final target deceleration xg ^* becomes zero after the brake operation amount becomes zero as compared with the case of the first embodiment. Drag increases.

Therefore, in the fourth embodiment, the predetermined gradient brkdn_dr that determines the decreasing gradient of the final target deceleration xg ^* is made larger than that in the first embodiment, so that the final required deceleration xg ^* after the driver required deceleration xg_dr ^* becomes zero ^. The time required for the value to become zero can be shortened. For this reason, the drag of the brake can be suppressed, and fluctuations in the longitudinal acceleration can be suppressed and smoothly connected to the lateral acceleration.

(Other examples)
As mentioned above, although the form for implementing this invention was demonstrated by the Example based on drawing, the concrete structure of this invention is not limited to what was shown in the Example, The summary of invention is changed. Even if there is a design change that does not occur, it is included in the present invention.

  In the first embodiment, an example in which the wheel cylinder pressure is increased as the automatic braking is shown, but the means for performing the automatic braking is arbitrary. For example, in a vehicle equipped with an engine as a drive source, the engine output may be reduced and the vehicle may be decelerated by engine braking. In a vehicle provided with an electric motor as a drive source, the regenerative braking force of the motor may be used. Further, the braking force may be generated by shifting down the transmission.

DESCRIPTION OF SYMBOLS 1 Brake control unit 2 Wheel speed sensor 3 Steering angle sensor 4 Accelerator switch 5 Brake stroke sensor 6 Yaw rate sensor 7 Acceleration sensor (lateral acceleration detection means)
8 Handle 9 Accelerator pedal 10 Brake pedal 11 Wheel cylinder 12 Hydraulic control unit 21 Yaw rate calculation unit 22 Road surface μ estimation unit 23 Lateral acceleration limit value calculation unit (operation start timing changing means)
24 control vehicle speed calculation unit 25 control deceleration calculation unit (control deceleration calculation means)
26 Driver demand deceleration calculation section (Driver demand deceleration calculation means)
27 Final target deceleration setting section (final target deceleration setting means)
28 Braking force control unit (braking force control means)

Claims (10)

A driver request deceleration calculation means for calculating a driver request deceleration according to the driver's brake operation;
A deceleration calculation means for control for calculating a deceleration for control which is a target value when the vehicle is automatically braked in accordance with a running state;
A final target deceleration setting means for setting a final target deceleration by selecting high of the driver requested deceleration and the control deceleration;
Braking force control means for controlling the braking force of the vehicle according to the final target deceleration;
In a vehicle braking force control device having:
A driver demand deceleration magnitude judging means for judging whether or not the driver demand deceleration is larger than the control deceleration;
When the automatic braking is activated during the driver's brake pedal depressing operation, the final target deceleration setting means determines that the driver requested deceleration is greater than the control deceleration by the driver requested deceleration magnitude determining means. A vehicle characterized in that, when it is determined that the speed is larger, a reduction rate of the final target deceleration is made smaller than a reduction rate of the driver required deceleration based on the values of the driver requested deceleration and the control deceleration. Braking force control device. A driver request deceleration calculation means for calculating a driver request deceleration according to the driver's brake operation;
A deceleration calculation means for control for calculating a deceleration for control which is a target value when the vehicle is automatically braked in accordance with a running state;
A final target deceleration is set by selecting high between the driver requested deceleration and the control deceleration, and when the driver is stepping back on the brake, the final target deceleration reduction rate is set to the driver requested deceleration. A final target deceleration setting means for making the reduction rate smaller than
Braking force control means for controlling the braking force of the vehicle according to the final target deceleration;
In a vehicle braking force control device having:
The final target deceleration setting means reduces the final target deceleration decrease rate as the difference between the driver requested deceleration and the control deceleration is smaller. . A driver request deceleration calculation means for calculating a driver request deceleration according to the driver's brake operation;
A deceleration calculation means for control for calculating a deceleration for control which is a target value when the vehicle is automatically braked in accordance with a running state;
A final target deceleration is set by selecting high between the driver requested deceleration and the control deceleration, and when the driver is stepping back on the brake, the final target deceleration reduction rate is set to the driver requested deceleration. A final target deceleration setting means for making the reduction rate smaller than
Braking force control means for controlling the braking force of the vehicle according to the final target deceleration;
In a vehicle braking force control device having:
The final target deceleration setting means reduces the final target deceleration decrease rate as the driver required deceleration is smaller. A driver request deceleration calculation means for calculating a driver request deceleration according to the driver's brake operation;
A deceleration calculation means for control for calculating a deceleration for control which is a target value when the vehicle is automatically braked in accordance with a running state;
A final target deceleration is set by selecting high between the driver requested deceleration and the control deceleration, and when the driver is stepping back on the brake, the final target deceleration reduction rate is set to the driver requested deceleration. A final target deceleration setting means for making the reduction rate smaller than
Braking force control means for controlling the braking force of the vehicle according to the final target deceleration;
In a vehicle braking force control device having:
Lateral acceleration detection means for detecting lateral acceleration acting on the vehicle,
The final target deceleration setting means reduces the final target deceleration reduction rate as the lateral acceleration of the vehicle is higher. A driver request deceleration calculation means for calculating a driver request deceleration according to the driver's brake operation;
A deceleration calculation means for control for calculating a deceleration for control which is a target value when the vehicle is automatically braked in accordance with a running state;
A final target deceleration is set by selecting high between the driver requested deceleration and the control deceleration, and when the driver is stepping back on the brake, the final target deceleration reduction rate is set to the driver requested deceleration. A final target deceleration setting means for making the reduction rate smaller than
Braking force control means for controlling the braking force of the vehicle according to the final target deceleration;
In a vehicle braking force control device having:
A braking force control device for a vehicle, comprising: an operation start timing changing means for advancing an operation start timing of automatic braking when the driver depresses the brake pedal. The vehicular braking force control apparatus according to claim 5 ,
The vehicular braking force control device according to claim 1, wherein the automatic braking start timing changing unit reduces the amount by which the operation start timing is advanced as the driver requested deceleration is smaller. A driver request deceleration calculation means for calculating a driver request deceleration according to the driver's brake operation;
A deceleration calculation means for control for calculating a deceleration for control which is a target value when the vehicle is automatically braked in accordance with a running state;
A final target deceleration is set by selecting high between the driver requested deceleration and the control deceleration, and when the driver is stepping back on the brake, the final target deceleration reduction rate is set to the driver requested deceleration. A final target deceleration setting means for making the reduction rate smaller than
Braking force control means for controlling the braking force of the vehicle according to the final target deceleration;
In a vehicle braking force control device having:
The final target deceleration setting means, when the accelerator operation is performed immediately after the brake pedal is stepped back and the automatic braking is continued, the reduction rate of the final target deceleration from the reduction rate of the control deceleration. A braking force control device for a vehicle, characterized in that A driver request deceleration calculation means for calculating a driver request deceleration according to the driver's brake operation;
A deceleration calculation means for control for calculating a deceleration for control which is a target value when the vehicle is automatically braked in accordance with a running state;
A final target deceleration is set by selecting high between the driver requested deceleration and the control deceleration, and when the driver is stepping back on the brake, the final target deceleration reduction rate is set to the driver requested deceleration. A final target deceleration setting means for making the reduction rate smaller than
Braking force control means for controlling the braking force of the vehicle according to the final target deceleration;
In a vehicle braking force control device having:
The final target deceleration setting means increases the reduction rate of the final target deceleration as the accelerator operation amount increases when the driver performs an accelerator operation while the automatic braking is continued. Power control device. A driver request deceleration calculation means for calculating a driver request deceleration according to the driver's brake operation;
A deceleration calculation means for control for calculating a deceleration for control which is a target value when the vehicle is automatically braked in accordance with a running state;
A final target deceleration is set by selecting high between the driver requested deceleration and the control deceleration, and when the driver is stepping back on the brake, the final target deceleration reduction rate is set to the driver requested deceleration. A final target deceleration setting means for making the reduction rate smaller than
Braking force control means for controlling the braking force of the vehicle according to the final target deceleration;
In a vehicle braking force control device having:
The final target deceleration setting means sets the final target deceleration when a deviation between the driver required deceleration and the control deceleration changes by a predetermined value. The final target deceleration is set based on the driver requested deceleration according to the driver's brake operation and the control deceleration that is the target value when the vehicle is automatically braked according to the driving state. In the vehicle braking force control method for controlling the braking force of the vehicle in response,
When the automatic braking is activated during the driver's brake pedal depressing operation, the driver request deceleration magnitude determining means determines that the driver request deceleration is greater than the control deceleration. A braking force control method for a vehicle, characterized in that a reduction rate of the final target deceleration is made smaller than a reduction rate of the driver required deceleration based on a value of deceleration and the control deceleration.

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