JP2011116237A - Braking system for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a braking system for a vehicle for suppressing the service brake fade and vapor lock. <P>SOLUTION: A braking ECU 41 determines whether at least one of a downhill flag Fa and a fade flag Fb is 1 in a step S17. When the determination result is Yes, the braking ECU 41 executes a fade restriction process in a step S18. Next, the braking ECU 41 determines whether a pressure flag Fc is 1 in a step S19. When the determination result is Yes, the braking ECU 41 executes a pressure process in a step S20. Then, the braking ECU 41 determines whether the pressure flag Fc is 1 in a step S21. When the determination result is Yes, the braking ECU 41 executes a high G braking process in a step S22. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a vehicle braking system mounted on a four-wheel automobile or the like, and more particularly to a technique for suppressing fade and vapor lock of a service brake.

  In a four-wheeled vehicle, a hydraulic disc brake or drum brake is generally used as a service brake (service brake) used for braking during traveling. In a hydraulic disc brake (hereinafter simply referred to as a hydraulic brake), when the driver steps on the brake pedal, the stepping force is amplified by the master power (vacuum booster) and transmitted to the master cylinder. The brake fluid is supplied to the brake caliper of each wheel. In the brake caliper, the caliper piston driven by the brake fluid presses the brake pad against the brake disc with a large pressing force, and a friction force is generated between the brake disc and the brake pad. The rotational energy is converted into thermal energy and braking is performed.

In a hydraulic brake, if braking is frequently performed when traveling downhill or traveling on a curved road, the balance between heat reception and heat dissipation is lost, and the temperature of the brake pad and caliper piston gradually increases. If the temperature of the brake pad or caliper piston rises significantly, fade (deterioration of the friction coefficient of the brake pad surface) due to alteration of the brake pad or vapor lock (generation of bubbles in the brake fluid) due to boiling of the brake fluid occurs. In some cases, the braking force decreased rapidly. In order to solve such problems, an electric brake (electric parking brake) that performs braking by an electric actuator is provided, and when it is detected that a fade has occurred in the hydraulic brake, a braking force corresponding to the amount of decrease in the braking force of the hydraulic brake Technology (see Patent Document 1), and the brake temperature of each wheel is detected individually, and if the brake of a specific wheel has faded, the control amount of that brake is increased to increase the intention. Technology that suppresses the generation of unintentional yaw moment (see Patent Document 2), and if the approaching road is a downhill with a large slope, increase the braking amount by other brakes (engine brakes and regenerative brakes) A technique (see Patent Document 3) that suppresses fading by reducing the load has been proposed.
JP 2008-174114 A JP 2009-12658 A JP 2005-138816 A

  The above-described devices of Patent Documents 1 and 2 deal with a decrease in braking force and generation of a yaw moment after determining the fade of the service brake. However, when fading actually occurs in the service brake, there is a problem that it takes a long time for the fading to be resolved by recovering the braking force due to the temperature drop of the brake pads and the like. In addition, when a vapor lock occurs in the service brake, it takes more time for the bubbles to disappear completely (vapour liquefies again) due to a decrease in the temperature of the brake fluid, which may necessitate replacement of the brake fluid. . Moreover, although the apparatus of patent document 3 aims at the fade suppression of a service brake, since there is no consideration about the brake distribution ratio of a service brake and another brake, the driver | operator's request | requirement deceleration cannot be obtained. There was sex.

  The present invention has been made in view of such a background, and an object of the present invention is to provide a vehicle braking system that suppresses service brake fading and vapor lock.

  A first aspect of the present invention is a braking system used for braking a vehicle, wherein main braking means for braking a wheel with a main braking amount, auxiliary braking means for braking a wheel with an auxiliary braking amount, and a driver's braking operation Based on the amount, target deceleration setting means for setting the target deceleration of the vehicle, target total braking amount setting means for setting the target total braking amount based on the target deceleration, and based on a predetermined braking distribution ratio, Brake distribution means for allocating the target total braking quantity between the target main braking quantity and the target auxiliary braking quantity, maximum auxiliary braking quantity estimating means for judging the maximum auxiliary braking quantity of the auxiliary braking means, and the maximum auxiliary braking quantity The difference from the target auxiliary braking amount is calculated as an auxiliary braking residual force, the upper limit value setting means for setting the upper limit value of the main braking amount according to the auxiliary braking residual force, and in the process of increasing the target total braking amount, Target main braking amount is before When having reached the upper limit value, to respond to the increase of the target total braking amount, characterized in that a distribution correction means for increasing the target assist braking amount within the range of the auxiliary braking margin.

  According to a second aspect of the present invention, in the vehicle braking system according to the first aspect of the present invention, the vehicle braking system includes a main braking capability determining unit that determines whether or not there is a possibility that the braking capability of the main braking unit is reduced. When the main braking capability determining unit determines that the braking capability of the main braking unit may be reduced, the correcting unit is configured to perform the target assisting even when the target main braking amount has not reached the upper limit value. The distribution by the braking distribution means is corrected so as to increase the braking amount.

  According to a third aspect of the present invention, in the vehicular braking system according to the first or second aspect of the present invention, based on the detection result of the driving state quantity detecting means for detecting the driving state quantity of the vehicle and the driving state quantity detecting means, If the downhill travel determination means for determining whether or not the vehicle is traveling downhill down a slope with a slope greater than a predetermined value, and the downhill travel determination means determines that the vehicle is traveling downhill, the target A descending slope braking amount correcting means for increasing the total braking amount, and the distribution correcting means increases the target auxiliary braking amount when the descending slope traveling determining means determines that the descending slope traveling determining means is traveling downhill. The distribution by the braking distribution means is corrected.

  According to a fourth aspect of the present invention, there is provided a braking system provided for braking the vehicle, the main braking means for braking the wheel with a main braking amount, and the auxiliary braking means including a regenerative brake for braking the wheel with the auxiliary braking amount. A target deceleration setting means for setting a target deceleration of the vehicle based on a braking operation amount of the driver; a target total braking amount setting means for setting a target total braking amount based on the target deceleration; A brake distribution means for allocating the target total braking amount to a target main braking amount and a target auxiliary braking amount based on a braking distribution ratio; an anti-lock brake system for suppressing wheel locking using the main braking means; and a road surface ABS operation determining means for determining whether or not the anti-lock brake system is likely to operate based on the state, and the distribution correction means is provided by the ABS operation determining means. If the anti-lock brake system is determined to be likely to operate, and corrects the allocation by the braking distribution means in order to increase the target main braking amount.

  According to a fifth invention, in the vehicle braking system according to the first to fourth inventions, the auxiliary braking means includes a regenerative brake and an electric brake.

According to the first invention, after distributing the target total braking amount to the target main braking amount and the target auxiliary braking amount,
The upper limit value of the target main braking amount is set according to the auxiliary braking residual force, and the target auxiliary braking amount is increased within the range of the auxiliary braking residual force so that the target main braking amount does not exceed the upper limit value. And the necessary deceleration can be secured while effectively suppressing vapor lock. Further, according to the second invention, since the main braking amount is reduced in advance when there is a possibility that the capability of the main braking means may be reduced, fade and vapor lock due to heating of the brake pads and the like can be prevented in advance. . According to the third aspect of the invention, since the target total braking amount is increased or decreased according to the vehicle speed, the front / rear G or the like, the necessary deceleration can be secured while further effectively suppressing the fade and vapor lock of the main braking means. According to the fourth aspect of the present invention, during downhill travel, the target total braking amount is increased to suppress a decrease in deceleration due to gravity acceleration, and the target main braking amount is relatively reduced. Fade and vapor lock of the main braking means are suppressed. According to the fifth aspect of the invention, it is possible to reduce the power generation load of the alternator by converting the kinetic energy of the vehicle into electric energy by the regenerative brake, and to regenerate due to the vehicle speed, the state of charge of the battery, and the like. Even when braking with only the brake cannot be performed, a desired deceleration can be realized by using the electric brake together.

1 is a plan view showing a schematic configuration of a vehicle according to an embodiment. It is a mimetic diagram showing the composition of the brake system concerning an embodiment. It is a block diagram which shows the structure of braking ECU which concerns on embodiment. It is a flowchart which shows the procedure of the braking control which concerns on embodiment. It is a flowchart which shows the procedure of the braking control which concerns on embodiment. It is a figure which shows the deceleration ratio of each braking means which concerns on embodiment, and the upper limit of a hydraulic brake. It is a graph which shows the braking amount change of each braking means in the case of a hydraulic brake main body. It is a graph which shows the amount of braking changes before amendment of each brake means in the case of an auxiliary brake means main part. It is a graph which shows the braking amount ratio before correction | amendment of each braking means in the case of an auxiliary | assistant braking means main body. It is a graph which shows the amount of braking changes after amendment of each brake means in the case of an auxiliary brake means main part. It is a graph which shows the braking amount ratio after correction | amendment of each braking means in the case of an auxiliary | assistant braking means main body.

  Hereinafter, an embodiment in which the present invention is applied to a braking system for a hybrid four-wheel vehicle will be described in detail with reference to the drawings.

<< Configuration of Embodiment >>
<Vehicle device configuration>
First, an apparatus configuration of an automobile will be described with reference to FIG. In the description, for the four wheels and the members arranged corresponding thereto, subscripts indicating front, rear, left, and right are attached to the numerical symbols, for example, wheel 4fl (front left), wheel 4fr (front right), wheel 4rl ( Left rear) and wheels 4rr (right rear), and collectively referred to as wheels 4 for example.

  As shown in FIG. 1, the automobile 1 has four wheels 4 with tires 3 mounted on the front, rear, left and right of the vehicle body 2, and an engine 11, a front motor 12, and an automatic transmission 13 at the front of the vehicle body. On the other hand, a rear motor 15 incorporating a differential gear is mounted at the rear of the vehicle body.

  A brake disk 21 is fastened / integrated to each wheel 4, and a hydraulic brake caliper 22 and an electric brake caliper 23 that brake the brake disk 21 are attached to a wheel support member (such as a knuckle) (not shown). A wheel speed sensor 25 for detecting the wheel speed Vw is installed in the vicinity of each wheel 4, and a caliper temperature sensor 26 is attached to each hydraulic brake caliper 22.

  In the present embodiment, the main braking means is a hydraulic brake that drives the hydraulic brake caliper 22. The auxiliary braking means includes an electric brake that drives the electric brake caliper 23, a regenerative brake that uses the front motor 12 and the rear motor 15, and an engine brake that uses the automatic transmission 13. The hydraulic unit 42 has an ABS function, and when any of the wheels 4 is locked, the brake fluid pressure Pb of the wheel 4 is intermittently reduced.

  A master power 32 connected to the brake pedal 31 and an electric vacuum pump 33 are installed in the engine room. As shown in FIG. 2, the master power 32 is integrally provided with a master cylinder 34, and is connected to the vacuum pump 33 and the intake manifold 35 of the engine 11 via negative pressure pipes 36 (36a, 36b). As a result, a predetermined negative pressure is generated inside. In FIG. 2, a member indicated by reference numeral 37 is a check valve interposed in the negative pressure pipe 36, and a member indicated by reference numeral 38 is a boost pressure sensor that detects the negative pressure (boost pressure Pbst) of the master power 32. A member denoted by reference numeral 39 is an intake manifold pressure sensor that detects the internal pressure of the intake manifold 35.

  As shown in FIG. 1, the vehicle body 2 includes a brake ECU 41 that performs overall control of the hydraulic brake and the auxiliary brake, a hydraulic unit 42 that controls brake pressure supplied to the hydraulic brake caliper 22, and shift control of the automatic transmission 13. A shift ECU 43 for performing the above, an electric brake ECU 44 for driving and controlling the electric brake caliper 23, and a motor ECU 45 for driving and controlling the front motor 12 and the rear motor 15 are provided. The ECUs 41, 43 to 45 and the hydraulic unit 42 are connected via a communication line (CAN (Controller Area Network in this embodiment)), and exchange signals with each other. In addition to the sensors 25, 26, 38, and 39 described above, the atmospheric pressure sensor 47 that detects atmospheric pressure, the longitudinal G sensor 48 that detects longitudinal acceleration, and the hydraulic pressure (brake hydraulic pressure Pb) input to the hydraulic unit 42. A brake pressure sensor 49 and the like for detecting the above are connected to the brake ECU 41.

<Brake ECU>
As shown in FIG. 3, the brake ECU 41 includes an input / output interface (not shown), a vehicle speed estimation unit 51, a target deceleration setting unit 52, a target total braking amount setting unit 53, a brake distribution setting unit 54, a maximum Auxiliary braking amount estimation unit 55, upper limit setting unit 56, distribution correction unit 57, main braking capacity determination unit 58, downhill travel determination unit 59, ABS operation determination unit 60, and high G braking determination unit 61 And.

  The vehicle speed estimation unit 51 estimates the vehicle speed V based on the wheel speed signal input from the wheel speed sensor 25 of each wheel 4. The target deceleration setting unit 52 sets the target deceleration Gtgt based on the brake fluid pressure Pb (that is, the operation amount of the brake pedal 31 by the driver) input from the brake pressure sensor 49. The target total braking amount setting unit 53 sets the target total braking amount Bgt based on the target deceleration Gtgt and the vehicle speed V input from the target deceleration setting unit 52. The braking distribution setting unit 54 sets a target main braking amount Bmt and a target auxiliary braking amount Bst from a braking distribution map (not shown) based on the target total braking amount Bgt.

  The maximum auxiliary braking amount estimation unit 55 estimates the sum of braking amounts that can be borne by each auxiliary braking means (electric brake, regenerative brake, engine brake) as the maximum auxiliary braking amount Bsmx. The upper limit setting unit 56 calculates the difference between the maximum auxiliary braking amount Bsmx and the target auxiliary braking amount Bst as the auxiliary braking residual force Bsmg, and then sets the upper limit value Bmmx of the main braking amount based on the auxiliary braking residual force Bsmg. When the target main braking amount Bmt reaches the upper limit value Bmmx, the distribution correcting unit 57 increases the target auxiliary braking amount Bst within the range of the auxiliary braking remaining force Bsmg so as to correspond to the increase in the target total braking amount Bgt.

  The main braking capacity determination unit 58 determines the possibility of a decrease in the braking capacity of the hydraulic brake (the possibility of fading) based on the detection signal of the caliper temperature sensor 26 and the like. The downhill traveling determination unit 59 determines whether or not the vehicle is traveling downhill based on the detection signal of the front / rear G sensor 48 and the like. The ABS operation determination unit 60 determines the ABS operation status including whether or not there is a possibility of operation based on the wheel speed signal input from each wheel speed sensor 25. The high G braking determination unit 61 determines whether braking at high deceleration has been performed based on the brake fluid pressure Pb or the like input from the brake pressure sensor 49.

<Operation of Embodiment>
When the driver performs a braking operation while the vehicle 1 is traveling (when the driver depresses the brake pedal 31 and the brake fluid pressure Pb becomes equal to or higher than a predetermined value), the brake ECU 41 is shown in the flowcharts of FIGS. The braking control indicating the procedure is repeatedly executed at a predetermined processing interval (for example, 10 ms).

  When the braking control is started, the braking ECU 41 estimates the gradient of the running road based on the detection signals of the front and rear G sensors 48 in step S1 of FIG. The gradient may be estimated from the rate of change of the vehicle speed V, the load state of the automatic transmission 13, and the like. Next, the braking ECU 41 determines in step S2 whether or not it is descending down a slope with a gradient greater than a predetermined value (that is, whether or not it is traveling downhill), and if this determination is Yes. In step S3, the downhill flag Fa is set to 1. If No, the downhill flag Fa is set to 0 in step S4.

  Next, the brake ECU 41 estimates the possibility that the hydraulic brake will fade in step S5 based on the detection signal of the caliper temperature sensor 26 and the like. In this estimation, the driver's required deceleration is calculated from the fluctuation amount of the boost pressure Pbst, the brake fluid pressure Pb, the vehicle speed V, etc., and the actual deceleration is less than this required deceleration. The amount of heat applied to the hydraulic brake caliper 22 is estimated from various information on the material, the vehicle speed V, and the brake hydraulic pressure Pb, and the friction coefficient of the friction material of the brake pad is less than a predetermined value from the brake hydraulic pressure Pb and the lock rate of each wheel 4. You may carry out by having fallen.

  Next, the brake ECU 41 determines whether or not the hydraulic brake may fade in step S6. If this determination is Yes, the fade flag Fb is set to 1 in step S7, and if it is No, in step S8. The fade flag Fb is set to 0.

  Next, the braking ECU 41 determines in step S9 whether the ABS is likely to operate from the vehicle speed V and the wheel speed Vw of each wheel 4 (that is, whether each wheel 4 tends to lock). presume.

  Next, in step S10, the brake ECU 41 determines whether or not the brake fluid pressure Pb has reached the ABS operating oil pressure despite the possibility that the ABS operates, and if this determination is Yes. In step S11, the pressurization flag Fc is set to 1. If No, the pressurization flag Fc is set to 0 in step S12.

  Next, in step S13, the braking ECU 41 estimates the necessity for high G braking from the rate of change of the vehicle speed V, the boost pressure Pbst, and the brake fluid pressure Pb. This estimation may be performed by installing a millimeter wave radar at the front of the vehicle body 2 and determining whether the distance from the preceding vehicle has suddenly decreased from the detection result.

  Next, the brake ECU 41 determines whether or not high G braking is necessary in step S14. If this determination is Yes, the high G flag Fd is set to 1 in step S15, and if it is No, in step S16. The high G flag Fd is set to 0.

  Next, the brake ECU 41 determines whether or not at least one of the downhill flag Fa and the fade flag Fb is 1 in step S17 of FIG. 5, and if this determination is Yes, the fade suppression process is performed in step S18. Execute. Specifically, the target main braking amount Bmt (brake hydraulic pressure Pb) is reduced, the target auxiliary braking amount Bst (braking amount by the electric brake, the regenerative brake and the engine brake) is increased, and the front wheel 4fl during downhill. , 4fr side target total braking amount is made larger than the rear wheel 4rl, 4rr side target total braking amount.

  Next, the brake ECU 41 determines whether or not the pressurization flag Fc is 1 in step S19. If this determination is Yes, the pressurization process is executed in step S20. Specifically, in order to secure a margin for operating the ABS, the target main braking amount Bmt is increased while the target auxiliary braking amount Bst is decreased.

  Next, the brake ECU 41 determines whether or not the pressurization flag Fc is 1 in step S21. If this determination is Yes, the high ECU braking process is executed in step S22. Specifically, the target auxiliary braking amount Bst is increased so as to complement the target main braking amount Bmt in order to secure the target total braking amount Bgt.

  Next, the braking ECU 41 determines whether or not the wheel 4 is locked in step S23, and if this determination is Yes, the ABS control process is executed in step S24.

<Hydraulic brake main>
When braking is performed mainly with the main braking means (hydraulic brake) and the auxiliary braking means (regenerative brake, engine brake, electric brake) are used together, the part to be supplemented by the auxiliary braking means is calculated from the current work of the hydraulic brake. Set an upper limit for the work of the hydraulic brake during downhill running and fading. For example, as shown in FIG. 6, if the deceleration ratio between hydraulic brake: regenerative brake: engine brake: electric brake is 10: 1: 2: 2, the upper limit value is 50%.

  As shown in FIG. 7, when it is determined that high G braking is performed, for example, when the driver depresses the brake pedal 31 strongly, the electric brake is actuated at that time to realize high G braking at a predetermined deceleration. This is because the electric brake operates instantaneously, and it is possible to compensate for the slow rise of the hydraulic pressure in the hydraulic brake, the strong depression of the brake pedal 31 and the maintenance of a high pedaling force, which are not good for the driver. As the braking amount of the hydraulic brake rises, the braking amount of the electric brake decreases, but the increase of the braking amount of the hydraulic brake is suppressed when the upper limit value Bmmx is reached. When the engine brake due to the downshift of the automatic transmission 13 starts to operate, the braking amount of the electric brake decreases and becomes zero. Further, when the hydraulic brake becomes faded and the braking amount decreases, the braking by the regenerative brake compensates for the decrease.

<Subsidiary auxiliary braking means>
(Before correction)
When braking is performed mainly using auxiliary braking means (regenerative brake, engine brake, electric brake) and also using a hydraulic brake, when the driver depresses the brake pedal 31, as shown in FIG. First, braking is performed, and when it is determined that high-G braking is performed, the electric brake is activated to realize high-G braking at a predetermined deceleration. Then, while the braking amount of the hydraulic brake rises, braking by the engine brake is also started, and the braking amount of the electric brake decreases. When reaching t1 in the middle speed range, the braking amount by the hydraulic brake decreases linearly, and the decrease is compensated by the engine brake and the electric brake. If the automatic transmission 13 includes a CVT or a torque converter, the braking amount of the engine brake is adjusted by driving and controlling the engine brake.

  As shown in FIG. 9, in the braking amount distribution before correction at time t1, the total braking amount is distributed to the regenerative brake, the hydraulic brake, and the engine brake, and the electric brake does not contribute to the braking. Further, at t1, there are braking surplus forces in the regenerative brake, engine brake, and electric brake, respectively, while a predetermined excess amount exists in the hydraulic brake.

(After correction)
When the above-described correction by the distribution correction unit 57 is performed, as shown in FIGS. 10 and 11, when the braking amount of the hydraulic brake reaches the upper limit value Bmmx, braking of the electric brake, the engine brake, and the regenerative brake is performed. The braking by the surplus force is added, and the increase in the braking amount of the hydraulic brake is suppressed. As a result, the load on the hydraulic brake is reduced, and the possibility of occurrence of fade and vapor lock becomes extremely small. Note that the ratio of the braking by the electric brake, the engine brake, and the regenerative brake is set in consideration of the amount of remaining power and controllability.

  Although description of specific embodiment is finished above, the aspect of the present invention is not limited to the above embodiment. For example, although the above embodiment is an application of the present invention to a brake system for a hybrid four-wheeled vehicle, it can naturally be applied to a gasoline engine vehicle, an electric vehicle, and the like. In addition, the specific configuration of the vehicle, the specific procedure of the control, and the like can be changed as appropriate without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 1 Car 2 Car body 3 Tire 4 Wheel 11 Engine 12 Front motor 13 Automatic transmission 15 Rear motor 21 Brake disk 22 Hydraulic brake caliper 23 Electric brake caliper 41 Braking ECU
42 Hydraulic unit 43 Speed change ECU
44 Electric brake ECU
45 Motor ECU
REFERENCE SIGNS LIST 51 Vehicle speed estimation unit 52 Target deceleration setting unit 53 Target total braking amount setting unit 54 Braking distribution setting unit 55 Maximum auxiliary braking amount estimation unit 56 Upper limit setting unit 57 Distribution correction unit 58 Main braking capacity determination unit 59 Downhill travel determination unit 60 ABS operation determination unit 61 High G braking determination unit

Claims (5)

A braking system for braking a vehicle,
Main braking means for braking the wheel with a main braking amount;
Auxiliary braking means for braking the wheel with an auxiliary braking amount;
A target deceleration setting means for setting a target deceleration of the vehicle based on a driver's braking operation amount;
Target total braking amount setting means for setting a target total braking amount based on the target deceleration;
Braking distribution means for distributing the target total braking amount to a target main braking amount and a target auxiliary braking amount based on a predetermined braking distribution ratio;
Maximum auxiliary braking amount estimating means for determining the maximum auxiliary braking amount of the auxiliary braking means;
An upper limit value setting means for calculating a difference between the maximum auxiliary braking amount and the target auxiliary braking amount as an auxiliary braking margin, and setting an upper limit value of the main braking amount according to the auxiliary braking margin;
When the target main braking amount reaches the upper limit in the process of increasing the target total braking amount, the target auxiliary braking amount is set within the range of the auxiliary braking residual force in order to cope with the increase in the target total braking amount. A vehicular braking system comprising distribution correction means for increasing. A main braking capability determining unit that determines whether or not the braking capability of the main braking unit may be reduced;
The distribution correction means, when it is determined by the main braking capacity determination means that there is a possibility that the braking capacity of the main braking means will decrease, even when the target main braking amount has not reached the upper limit value, 2. The vehicle braking system according to claim 1, wherein the distribution by the braking distribution means is corrected to increase the target auxiliary braking amount. Driving state quantity detecting means for detecting the driving state quantity of the vehicle;
Based on the detection result of the driving state quantity detection means, downhill running determination means for determining whether or not the vehicle is running downhill down a slope with a slope greater than a predetermined value;
When it is determined that the downhill running determination means is running downhill, the downhill braking amount correction means for increasing the target total braking amount,
The distribution correction means corrects the distribution by the braking distribution means to increase the target auxiliary braking amount when the downhill traveling determination means determines that the vehicle is traveling downhill. A braking system for a vehicle according to claim 1 or 2. A braking system for braking a vehicle,
Main braking means for braking the wheel with a main braking amount;
Auxiliary braking means including a regenerative brake for braking the wheel with an auxiliary braking amount;
A target deceleration setting means for setting a target deceleration of the vehicle based on a driver's braking operation amount;
Target total braking amount setting means for setting a target total braking amount based on the target deceleration;
Braking distribution means for distributing the target total braking amount to a target main braking amount and a target auxiliary braking amount based on a predetermined braking distribution ratio;
An anti-lock brake system that suppresses locking of the wheels using the main braking means;
ABS operation determination means for determining whether or not the anti-lock brake system is likely to operate based on a road surface state,
The distribution correction means corrects the distribution by the brake distribution means to increase the target main braking amount when it is determined by the ABS operation determination means that the antilock brake system is likely to operate. A braking system for a vehicle.   The vehicular braking system according to any one of claims 1 to 4, wherein the auxiliary braking means includes a regenerative brake and an electric brake.

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