Braking control device

Abstract

To provide a braking control device, which is configured to suppress occurrence of a deviation between behavior of a vehicle which an occupant in the vehicle feels and actual behavior of the vehicle, when applying braking force to the vehicle to stop the vehicle on a downslope road.SOLUTION: A processing circuit 51 of a braking control device 50 functions as: a control part M11 that executes stop-time braking control for changing an allocation ratio between first braking force and second braking force so that the second braking force increases, before stopping a vehicle 10 by applying braking force to the vehicle 10 to stop the vehicle; and a setting part M15 that when a road surface on which the vehicle 10 is running is a downslope road, sets the allocation ratio at the time of executing the stop-time braking control so that an increase in second braking force is suppressed in comparison with when the running road surface is not the downslope road.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a braking control device that controls the braking force applied to a vehicle.

Background Art

[0002] Patent Document 1 discloses a braking control device that adjusts the distribution ratio between the front-wheel braking force and the rear-wheel braking force. The front-wheel braking force is the braking force applied to the front wheels. The rear-wheel braking force is the braking force applied to the rear wheels. The braking control device changes the above distribution ratio so that the rear-wheel braking force increases immediately before the vehicle that is decelerating due to the application of the braking force stops. As a result, since the restraining force, which is the force for suppressing the pitching motion of the vehicle, increases, the braking control device can mitigate the rocking-back behavior of the vehicle during stopping.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When a braking force is applied to a vehicle, an inertial force acts on the vehicle, causing the vehicle to perform a pitching motion. When the pitching angle of the vehicle increases due to the pitching motion of the vehicle, the line of sight of the vehicle occupant moves downward in response to the fluctuation of the pitching angle. When the line of sight of the occupant moves downward in this way, the occupant can visually perceive that the vehicle is decelerating.

[0005] When the above distribution ratio is changed so that the rear wheel braking force increases, the pitch angle of the vehicle decreases. When the pitch angle decreases, the line of sight of the occupant moves upward. When the line of sight of the occupant moves upward immediately before stopping on a downhill road, the occupant may feel that the deceleration of the vehicle has visually decreased. As a result, since the occupant feels that the vehicle cannot be stopped on a downhill road, the occupant may feel discomfort.

Means for Solving the Problems

[0006] The braking control device for solving the above problems includes a first braking unit that applies a first braking force to the vehicle and a second braking unit that applies a second braking force to the vehicle. When the first braking unit applies the first braking force to the vehicle, the attitude change of the vehicle in the pitch on the nose dive side that gives the vehicle the first braking force of the same magnitude as the second braking force applied by the second braking unit to the vehicle is greater than the attitude change given to the vehicle when the second braking unit applies the second braking force of the same magnitude to the vehicle. The braking control device applies to the vehicle. When braking the vehicle to a stop, the control unit performs stop-time braking control to change the distribution ratio of the first braking force and the second braking force so that the second braking force increases before the vehicle stops, and when the traveling road surface of the vehicle is a downhill road, a setting unit that sets the distribution ratio at the time of execution of the stop-time braking control to suppress an increase in the second braking force as compared with the case where the traveling road surface is not a downhill road.

Advantages of the Invention

[0007] The above braking control device has an effect of suppressing a deviation from occurring between the behavior of the vehicle felt by the occupant of the vehicle and the actual behavior of the vehicle when stopping the vehicle on a downhill road by applying a braking force.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

DETAILED DESCRIPTION OF THE INVENTION

[0009] (First Embodiment) Hereinafter, a first embodiment of the braking control device will be described with reference to FIGS. 1 to 5. FIG. 1 shows a vehicle 10 equipped with a braking control device 50. The vehicle 10 includes a braking operation member 11, a plurality of wheels, a plurality of friction brakes, and a braking actuator 30. The braking operation member 11 is a member operated by a driver when applying a braking force to the vehicle 10. An example of the braking operation member 11 is a brake pedal. The plurality of wheels includes two front wheels 12 and two rear wheels 13.

[0010] <Friction Brake> The plurality of friction brakes respectively apply a frictional braking force to the corresponding wheels. Among the plurality of friction brakes, the friction brake corresponding to the front wheel 12 is referred to as "friction brake 20A", and the friction brake corresponding to the rear wheel 13 is referred to as "friction brake 20B". The friction brakes 20A and 20B have a wheel cylinder 21, a rotating body 22, and a friction portion 23. The rotating body 22 rotates integrally with the wheel. Therefore, by pressing the friction portion 23 against the rotating body 22, a braking force is applied to the wheel. The force for pressing the friction portion 23 against the rotating body 22 increases as the wheel hydraulic pressure, which is the hydraulic pressure in the wheel cylinder 21, increases. Therefore, the friction brakes 20A and 20B can apply a larger frictional braking force to the wheel as the wheel hydraulic pressure increases.

[0011] In the following description, the wheel hydraulic pressure of the wheel cylinder 21 of the friction brake 20A is referred to as "front-wheel wheel hydraulic pressure PwcF". The wheel hydraulic pressure of the wheel cylinder 21 of the friction brake 20B is referred to as "rear-wheel wheel hydraulic pressure PwcR". The frictional braking force applied to the front wheels 12 by the friction brake 20A is referred to as "front-wheel frictional braking force BPFF". The frictional braking force applied to the rear wheels 13 by the friction brake 20B is referred to as "rear-wheel frictional braking force BPFR".

[0012] <Brake actuator> The brake actuator 30 controls the frictional braking forces BPFF and BPFR applied to the wheels 12 and 13 by controlling the wheel hydraulic pressures PwcF and PwcR of the plurality of wheel cylinders 21. For example, the brake actuator 30 has a pressure source that supplies brake fluid to the plurality of wheel cylinders 21. The pressure source is, for example, an electric pump and an electric cylinder. The brake actuator 30 can adjust the front-wheel wheel hydraulic pressure PwcF and the rear-wheel wheel hydraulic pressure PwcR individually.

[0013] In the following description, the sum of the braking forces applied to the plurality of wheels 12 and 13 is referred to as "vehicle braking force BPAl". While frictional braking force is applied to the vehicle 10, regenerative braking force is not applied. Therefore, in the vehicle 10, the sum of the front-wheel frictional braking force BPFF and the rear-wheel frictional braking force BPFR corresponds to the vehicle braking force BPAl.

[0014] <Detection system> The detection system of the vehicle 10 includes a plurality of sensors that output detection signals to the brake control device 50. The plurality of sensors include a brake sensor 101, a plurality of wheel speed sensors 102, and a front-rear acceleration sensor 103.

[0015] The brake sensor 101 detects information related to the operation of the braking operation member 11 by the driver. An example of the brake sensor 101 is a stroke sensor that detects the operation amount of the driver's braking operation member 11. The operation amount based on the detection signal of the brake sensor 101 is referred to as "braking operation amount X". Note that the detection system may have a sensor that detects the operation force of the driver's braking operation member 11.

[0016] The wheel speed sensors 102 are provided for each of the plurality of wheels. The plurality of wheel speed sensors 102 respectively detect the rotational speed of the corresponding wheels. The rotational speed of the wheels based on the detection signal of the wheel speed sensors 102 is referred to as "wheel speed VW". The traveling speed of the vehicle 10 calculated based on the wheel speeds VW of the plurality of wheels 12, 13 is referred to as "vehicle body speed VS".

[0017] The longitudinal acceleration sensor 103 detects the acceleration in the longitudinal direction of the vehicle 10 among the accelerations acting on the vehicle 10. The acceleration in the longitudinal direction of the vehicle 10 based on the detection signal of the longitudinal acceleration sensor 103 is referred to as "longitudinal acceleration Gx".

[0018] <Change in vehicle posture during braking> Referring to FIG. 2, the forces acting on the vehicle 10 during braking and the motion of the vehicle 10 above the spring will be described. FIG. 2 shows the vehicle center of gravity GC of the vehicle 10. In FIG. 2, the horizontal distance between the vehicle center of gravity GC and the axle of the front wheels 12 in the longitudinal direction of the vehicle 10 is shown as the first distance Lf, and the horizontal distance between the vehicle center of gravity GC and the axle of the rear wheels 13 in the longitudinal direction of the vehicle 10 is shown as the "second distance Lr". The sum of the first distance Lf and the second distance Lr corresponds to the "wheelbase L of the vehicle 10".

[0019] When the vehicle brakes, a pitching moment My as shown by the arrow in Fig. 2 is generated around the vehicle's center of gravity GC. When the pitching moment My is generated in the vehicle 10, the vehicle 10 pitches in the nose-dive direction. Nose-dive refers to the behavior of the vehicle 10 that displaces the front part of the vehicle body 19 downward and the rear part of the vehicle body 19 upward. On the other hand, the behavior of the vehicle 10 that displaces the front part of the vehicle body 19 upward and the rear part of the vehicle body 19 downward is called "nose lift". The larger the magnitude of the pitching moment My, the larger the pitch angle θ becomes, or the larger the rate of increase of the pitch angle θ becomes. On the other hand, when the attitude of the vehicle 10 changes in the nose-lift direction, the pitch angle θ becomes smaller.

[0020] In Fig. 2, the contact point where the front-wheel frictional braking force BPFF acts is shown as the first action point PA1, and the contact point where the rear-wheel frictional braking force BPFR acts is shown as the second action point PA2.

[0021] In Fig. 2, the instantaneous rotation centers of the wheels are illustrated. The instantaneous rotation center of the front wheel 12 during vehicle braking is shown as the front-wheel rotation center Cf. The angle formed by the straight line connecting the first action point PA1 and the front-wheel rotation center Cf and the road surface 100 is shown as the first angle θfb. Similarly, the instantaneous rotation center of the rear wheel 13 during vehicle braking is shown as the rear-wheel rotation center Cr. The angle formed by the straight line connecting the second action point PA2 and the rear-wheel rotation center Cr and the road surface 100 is shown as the second angle θrb.

[0022] Note that the positions of the plurality of instantaneous rotation centers are respectively determined by the characteristics of the suspension device. The positions of the plurality of instantaneous rotation centers shown in Fig. 2 are an example and do not represent the actual positions of the instantaneous rotation centers. Therefore, the magnitudes of the first angle θfb and the second angle θrb also do not indicate the actual magnitudes of the angles.

[0023] As shown by the white arrow in Fig. 2, when the vehicle is braking, an anti-dive force FAD acts on the front part of the vehicle 10 by the suspension device for the front wheels 12. Also, when the vehicle is braking, an anti-lift force FAL acts on the rear part of the vehicle 10 by the suspension device for the rear wheels 13.

[0024] The anti-dive force FAD is a force that acts when a braking force is applied to the front wheels 12. The anti-dive force FAD is a force that suppresses the sinking of the front part of the vehicle body. The direction in which the anti-dive force FAD acts is a direction that displaces the front part of the vehicle body away from the road surface 100.

[0025] The anti-lift force FAL is a force that acts when a braking force is applied to the rear wheels 13. The anti-lift force FAL is a force that suppresses the lifting of the rear part of the vehicle body. The direction in which the anti-lift force FAL acts is a direction that displaces the rear part of the vehicle body closer to the road surface 100.

[0026] The anti-dive force FAD can be expressed by the following relational expression (D1). The anti-lift force FAL can be expressed by the following relational expression (D2). As is clear from the relational expression (D1), the larger the front wheel frictional braking force BPFF, the larger the anti-dive force FAD. As is clear from the relational expression (D2), the larger the rear wheel frictional braking force BPFR, the larger the anti-lift force FAL.

[0027] FAD = BPFF · tanθfb ···(D1) FAL = BPRF · tanθrb ···(D2) Vehicle 10 is a vehicle in which the pitching behavior of vehicle 10 in the pitching direction associated with the application of a desired amount of front-wheel frictional braking force BPFF to vehicle 10 is different from the pitching behavior of vehicle 10 in the pitching direction associated with the application of a desired amount of rear-wheel frictional braking force BPFR to vehicle 10. For example, vehicle 10 is configured such that the distribution ratio of the front-wheel frictional braking force BPFF and the rear-wheel frictional braking force BPFR can suppress the attitude change in the pitch on the nose dive side of vehicle 10 as the distribution ratio in which the rear-wheel frictional braking force BPFR increases. That is, vehicle 10 is configured such that the pitching suppression force increases as the distribution ratio in which the rear-wheel frictional braking force BPFR is large. The pitching suppression force is the sum of the anti-dive force FAD and the anti-lift force FAL. Therefore, under the condition that the sum of the front-wheel frictional braking force BPFF and the rear-wheel frictional braking force BPFR is the same, the increase in the pitch angle θ is suppressed or the increase rate of the pitch angle θ becomes smaller as the rear-wheel frictional braking force BPFR is larger.

[0028] Therefore, in the present embodiment, the front-wheel frictional braking force BPFF corresponds to the "first braking force", and the rear-wheel frictional braking force BPFR corresponds to the "second braking force". Further, the friction brake 20A that applies the front-wheel frictional braking force BPFF to the front wheels 12 corresponds to the "first braking part". The friction brake 20B that applies the rear-wheel frictional braking force BPFR to the rear wheels 13 corresponds to the "second braking part".

[0029] <Brake control device> As shown in FIG. 1, the brake control device 50 includes a processing circuit 51. An example of the processing circuit 51 is an electronic control device. In this case, the processing circuit 51 has a CPU 52, a first memory 53, and a second memory 54. The first memory 53 stores a control program executed by the CPU 52. The second memory 54 stores the calculation results of the CPU 52 and the like. By the CPU 52 executing the control program of the first memory 53, the processing circuit 51 controls the brake actuator 30 to operate the plurality of friction brakes 20A, 20B. That is, the processing circuit 51 can adjust the vehicle braking force BPAl by operating the plurality of friction brakes 20A, 20B.

[0030] <Overview of Braking Control at Stop> The processing circuit 51 performs braking control at stop immediately before the vehicle 10 stops. The braking control at stop is braking control for suppressing changes in the posture of the vehicle 10 when it stops.

[0031] Referring to FIG. 3, the braking control at stop will be described. FIG. 3 illustrates an example of the case where the braking control at stop is performed when the vehicle 10 is stopped on a horizontal road. At timing t11 in the situation where the vehicle 10 is running, the driver starts operating the braking operation member 11. In this case, as shown in FIG. 3(B), the processing circuit 51 derives the required braking force BPRq. The required braking force BPRq is the required value of the vehicle braking force BPAl. For example, the processing circuit 51 derives the required braking force BPRq such that the value increases as the braking operation amount X of the braking operation member 11 increases. When the vehicle body speed VS of the vehicle 10 is greater than the first vehicle body speed determination value VSth1 as before timing t12, as shown in FIG. 3(D), the processing circuit 51 sets the required braking force BPRq as the instructed braking force BPTr. Then, the processing circuit 51 controls the brake actuator 30 so that the vehicle braking force BPAl becomes the instructed braking force BPTr.

[0032] At this time, as shown in FIG. 3(E), the processing circuit 51 controls the brake actuator 30 so that the front wheel wheel hydraulic pressure PwcF and the rear wheel wheel hydraulic pressure PwcR become the same pressure. Thereby, the front wheel frictional braking force BPFF corresponding to the front wheel wheel hydraulic pressure PwcF is applied to the front wheels 12. The rear wheel frictional braking force BPFR corresponding to the rear wheel wheel hydraulic pressure PwcR is applied to the rear wheels 13. Hereinafter, the distribution ratio α of the front wheel frictional braking force BPFF and the rear wheel frictional braking force BPFR when the front wheel wheel hydraulic pressure PwcF and the rear wheel wheel hydraulic pressure PwcR are the same pressure is referred to as the "reference distribution ratio αdb".

[0033] When a braking force is applied to the vehicle 10, the vehicle body speed VS decreases as shown in FIG. 3(A). Also, as shown in FIG. 3(C), the absolute value of the longitudinal acceleration Gx increases as the vehicle braking force BPAl increases.

[0034] When the vehicle body speed VS reaches the first vehicle body speed determination value VSth1 at timing t12, the processing circuit 51 starts the stop-time braking control. The first vehicle body speed determination value VSth1 is an example of a threshold value for setting the start timing of the stop-time braking control. From timing t12, the processing circuit 51 starts the supplementary correction processing of the stop-time braking control. In the supplementary correction processing, the processing circuit 51 sets a braking force larger than the required braking force BPRq as the commanded braking force BPTr. For example, the processing circuit 51 sets the sum of the required braking force BPRq and the offset value ΔBP as the commanded braking force BPTr. Then, the processing circuit 51 controls the brake actuator 30 so that the vehicle braking force BPAl becomes the commanded braking force BPTr. Thereby, even if the required braking force BPRq is the same, the absolute value of the longitudinal acceleration Gx of the vehicle 10 becomes larger than before timing t12 by the amount of the offset value ΔBP.

[0035] As shown in (E) of FIG. 3, before the vehicle 10 stops, the processing circuit 51 changes the distribution ratio α so that the rear-wheel frictional braking force BPFR increases. When the stop-time braking control is started, the distribution ratio α is changed to a ratio that makes the rear-wheel frictional braking force BPFR larger than the reference distribution ratio αdb.

[0036] Thereby, before the vehicle 10 stops, the pitching suppression force becomes larger as compared with the case where the distribution ratio α is maintained at the reference distribution ratio αdb. Thereby, the pitch angle θ of the vehicle 10 before stopping becomes smaller.

[0037] At timing t13, the vehicle body speed VS becomes the second vehicle body speed determination value VSth2. A vehicle body speed smaller than the first vehicle body speed determination value VSth1 is set as the second vehicle body speed determination value VSth2. When the vehicle body speed VS is equal to or lower than the second vehicle body speed determination value VSth2, it can be considered that the vehicle 10 has approached the stop position PS. The stop position PS is the predicted position where the vehicle 10 stops. The processing circuit 51 shifts the processing of the stop-time braking control from the plus correction processing to the minus correction processing. In the minus correction processing, the processing circuit 51 decreases the indicated braking force BPTr at a constant speed. Then, the processing circuit 51 controls the braking actuator 30 so that the vehicle braking force BPAl becomes the indicated braking force BPTr. By the processing circuit 51 executing the minus correction processing in this way, the vehicle braking force BPAl becomes smaller than the required braking force BPRq. As a result, even if the required braking force BPRq is the same, the absolute value of the longitudinal acceleration Gx of the vehicle 10 gradually becomes smaller.

[0038] At timing t14, the indicated braking force BPTr becomes equal to the stop-maintaining braking force BPth. As the stop-maintaining braking force BPth, the minimum braking force necessary to maintain the stop of the vehicle 10 on the current traveling road surface of the vehicle 10, or a braking force slightly larger than the braking force, is set. This stop-maintaining braking force BPth is an example of the "predetermined braking force". From timing t14, in the minus correction processing, the processing circuit 51 holds the indicated braking force BPTr at the stop-maintaining braking force BPth.

[0039] At timing t15, the processing circuit 51 determines that the vehicle 10 has stopped, and thus shifts the processing of the stop-time braking control from the minus correction processing to the degradation processing. In the degradation processing, the processing circuit 51 increases the indicated braking force BPTr. For example, the processing circuit 51 increases the indicated braking force BPTr to the required braking force BPRq. By the processing circuit 51 controlling the braking actuator 30 based on the indicated braking force BPTr, the vehicle braking force BPAl increases.

[0040] As shown in (E) of FIG. 3, in the degradation processing, the processing circuit 51 controls the braking actuator 30 so that the above distribution ratio α gradually returns to the reference distribution ratio αdb. After that, when the indicated braking force BPTr becomes equal to the required braking force BPRq at timing t16, the processing circuit 51 ends the braking control at stop.

[0041] <Functional configuration of the processing circuit> Referring to FIG. 1, the functional configuration of the processing circuit 51 will be described. By the CPU 52 executing the control program of the first memory 53, the processing circuit 51 functions as a plurality of functional units. These plurality of functional units are functional units for stopping the vehicle 10 by applying a braking force thereto. The plurality of functional units include, for example, a control unit M11, a gradient acquisition unit M13, and a setting unit M15.

[0042] <Control unit> When applying a braking force to the vehicle 10 to stop it, the control unit M11 performs braking control at stop. That is, when the start condition of the braking control at stop is satisfied, the control unit M11 starts the augmentation correction process. In the augmentation correction process, the control unit M11 sets the indicated braking force BPTr to a vehicle braking force greater than the required braking force BPRq. The offset value ΔBP, which is the augmentation correction amount of the indicated braking force BPTr at this time, is a correction amount of the braking force for compensating for the extension of the braking distance of the vehicle 10 caused by the execution of the subsequent reduction correction process.

[0043] In the augmentation correction process, the control unit M11 derives a front-wheel frictional braking force indicated value BPFFTr and a rear-wheel frictional braking force indicated value BPFRTr that satisfy the following conditions (A1) and (A2). The front-wheel frictional braking force indicated value BPFFTr is an indicated value of the front-wheel frictional braking force BPFF. The rear-wheel frictional braking force indicated value BPFRTr is an indicated value of the rear-wheel frictional braking force BPFR.

[0044] (A1) The sum of the front-wheel frictional braking force indicated value BPFFTr and the rear-wheel frictional braking force indicated value BPFRTr is equal to the indicated braking force BPTr. (A2) The target distribution ratio αd, which is the distribution ratio of the front-wheel frictional braking force indicated value BPFFTr and the rear-wheel frictional braking force indicated value BPFRTr, becomes the distribution ratio set by the setting unit M15 described later.

[0045] Then, the control unit M11 operates the brake actuator 30 based on the front-wheel frictional braking force instruction value BPFFTr and the rear-wheel frictional braking force instruction value BPFRTr. During the execution of the augmentation correction process, when the transition condition from the augmentation correction process to the reduction correction process is satisfied, the control unit M11 ends the augmentation correction process and starts the reduction correction process. In the reduction correction process, the control unit M11 reduces the commanded braking force BPTr to the parking maintenance braking force BPth that is smaller than the required braking force BPRq, and then sets the vehicle body speed VS to 0 (zero). Specifically, the control unit M11 reduces the commanded braking force BPTr to the parking maintenance braking force BPth. After the commanded braking force BPTr reaches the parking maintenance braking force BPth, the control unit M11 holds the commanded braking force BPTr at the parking maintenance braking force BPth. Then, the control unit M11 operates the brake actuator 30 based on the front-wheel frictional braking force instruction value BPFFTr and the rear-wheel frictional braking force instruction value BPFRTr.

[0046] During the execution of the reduction correction process, when the transition condition from the reduction correction process to the degradation process is satisfied, the control unit M11 ends the reduction correction process and starts the degradation process. In the degradation process, the control unit M11 increases the commanded braking force BPTr to the required braking force BPRq.

[0047] At this time, the control unit M11 derives the front-wheel frictional braking force instruction value BPFFTr and the rear-wheel frictional braking force instruction value BPFRTr such that the target distribution ratio αd gradually approaches the reference distribution ratio αdb from the distribution ratio set by the setting unit M15 described later. Then, the control unit M11 operates the brake actuator 30 based on the front-wheel frictional braking force instruction value BPFFTr and the rear-wheel frictional braking force instruction value BPFRTr.

[0048] <Gradient acquisition unit> The gradient acquisition unit M13 acquires the road surface gradient η, which is the gradient of the driving road surface of the vehicle 10. For example, the gradient acquisition unit M13 derives the difference between the differential value of the vehicle body speed VS of the vehicle 10 and the longitudinal acceleration Gx as the road surface gradient η. Note that the gradient acquisition unit M13 may acquire the road surface gradient η based on the information about the road surface obtained from the navigation device. Further, when the vehicle 10 is equipped with a sensor for detecting the degree of inclination of the vehicle body 19, the gradient acquisition unit M13 may acquire the detection value of the sensor as the road surface gradient η. Additionally, the gradient acquisition unit M13 may derive the road surface gradient η by analyzing the image captured by the in-vehicle camera.

[0049] <Setting unit> When the driving road surface of the vehicle 10 is a slope road, the setting unit M15 sets the target distribution ratio αd during the execution of the stop-time braking control to suppress the increase in the rear-wheel frictional braking force BPFR as compared with the case where the driving road surface is not a slope road.

[0050] Specifically, the setting unit M15 sets the target distribution ratio αd based on the road surface gradient η at the time when the start condition of the stop-time braking control is satisfied. For example, the setting unit M15 determines whether the driving road surface is a slope road based on the road surface gradient η at the time when the start condition of the stop-time braking control is satisfied. At this time, the setting unit M15 may determine that the driving road surface is a slope road when the absolute value of the road surface gradient η is greater than or equal to the gradient determination value ηth, while determining that the driving road surface is not a slope road when the absolute value of the road surface gradient η is less than the gradient determination value ηth. The gradient determination value ηth is set as a criterion for determining whether the road surface gradient η is a slope road.

[0051] When the setting unit M15 determines that the driving road surface is a slope based on the road surface gradient η at the time when the start condition of the stop-time braking control is satisfied, the target distribution ratio αd is set to a distribution ratio that suppresses the increase in the rear-wheel frictional braking force BPFR more than when it is determined that the driving road surface is not a slope. Specifically, when the setting unit M15 determines that the driving road surface is not a slope, it sets the specified distribution ratio αdc as the target distribution ratio αd. The specified distribution ratio αdc is a distribution ratio that makes the rear-wheel frictional braking force BPFR larger than the reference distribution ratio αdb. On the other hand, when the setting unit M15 determines that the driving road surface is a slope, it sets the target distribution ratio αd to a distribution ratio that makes the rear-wheel frictional braking force BPFR smaller than the specified distribution ratio αdc.

[0052] That is, when the driving road surface is a downhill slope, the setting unit M15 can set the target distribution ratio αd to a distribution ratio that suppresses the increase in the rear-wheel frictional braking force BPFR compared to the case where it is determined that the driving road surface is not a slope. Also, when the driving road surface is an uphill slope, the setting unit M15 can set the target distribution ratio αd to a distribution ratio that suppresses the increase in the rear-wheel frictional braking force BPFR compared to the case where it is determined that the driving road surface is not a slope.

[0053] In this embodiment, when the setting unit M15 determines that the driving road surface is a slope, it sets the target distribution ratio αd to a distribution ratio that more strongly suppresses the increase in the rear-wheel frictional braking force BPFR as the absolute value of the road surface gradient η is larger. Thereby, when the driving road surface is a downhill slope, the setting unit M15 can set the target distribution ratio αd to a distribution ratio that more strongly suppresses the increase in the rear-wheel frictional braking force BPFR as the gradient of the driving road surface is larger. Also, when the driving road surface is an uphill slope, the setting unit M15 can set the target distribution ratio αd to a distribution ratio that more strongly suppresses the increase in the rear-wheel frictional braking force BPFR as the gradient of the driving road surface is larger.

[0054] <Flow of processing during vehicle braking> Referring to FIG. 4, a series of processes when the processing circuit 51 executes the stop-time braking control will be described. The processing circuit 51 repeatedly executes a series of processes shown in FIG. 4 when the vehicle 10 is braked.

[0055] In step S11, the processing circuit 51 acquires a road surface gradient η, which is the gradient of the traveling road surface of the vehicle. In the next step S13, the processing circuit 51 determines whether the traveling road surface is an uphill or downhill road based on the road surface gradient η acquired in step S11. When the processing circuit 51 determines that the traveling road surface is an uphill or downhill road (S13: YES), the process proceeds to step S15. On the other hand, when the processing circuit 51 determines that the traveling road surface is not an uphill or downhill road (S13: NO), the process proceeds to step S41.

[0056] In step S15, the processing circuit 51 sets a distribution ratio corresponding to the road surface gradient η as the target distribution ratio αd. For example, the processing circuit 51 sets the target distribution ratio αd so as to more strongly suppress the increase in the rear-wheel frictional braking force BPFR as the magnitude of the road surface gradient η increases.

[0057] In the next step S17, the processing circuit 51 determines whether the start condition for the braking control at stop is satisfied. For example, as shown in FIG. 3, when the vehicle body speed VS decreases from a state where the vehicle body speed VS is greater than the first vehicle body speed determination value VSth1 to a value less than or equal to the first vehicle body speed determination value VSth1, the processing circuit 51 determines that the start condition is satisfied. When the processing circuit 51 determines that the start condition is satisfied (S17: YES), the process proceeds to step S20. On the other hand, when the processing circuit 51 determines that the start condition is not satisfied (S17: NO), the series of processes shown in FIG. 4 is temporarily terminated.

[0058] In step S20, the processing circuit 51 performs first braking control at stop as the braking control at stop. The first braking control at stop is the braking control at stop for stopping the vehicle 10 on an uphill or downhill road.

[0059] Specifically, in step S21, the processing circuit 51 executes an augmentation correction process. In the augmentation correction process, the processing circuit 51 sets the sum of the required braking force BPRq and the offset value ΔBP as the commanded braking force BPTr in order to compensate for the extension of the braking distance of the vehicle 10 caused by the execution of the reduction correction process. The processing circuit 51 derives the front-wheel frictional braking force command value BPFFTr and the rear-wheel frictional braking force command value BPFRTr so as to satisfy any of the above conditions (A1) and (A2). Then, the processing circuit 51 operates the braking actuator 30 based on the front-wheel frictional braking force command value BPFFTr and the rear-wheel frictional braking force command value BPFRTr.

[0060] In the subsequent step S23, the processing circuit 51 determines whether or not the transition condition from the augmentation correction process to the reduction correction process is satisfied. For example, when the vehicle body speed VS becomes equal to or less than the second vehicle body speed determination value VSth2 from a state where the vehicle body speed VS is greater than the second vehicle body speed determination value VSth2, the processing circuit 51 determines that the transition condition is satisfied. When the processing circuit 51 determines that the transition condition is not satisfied (S23: NO), the process proceeds to step S21. That is, the processing circuit 51 executes the augmentation correction process. On the other hand, when the processing circuit 51 determines that the transition condition is satisfied (S23: YES), the process proceeds to step S25.

[0061] In step S25, the processing circuit 51 executes the reduction correction process of the first stop-time braking control. In the reduction correction process, the processing circuit 51 decreases the commanded braking force BPTr to the stop-maintaining braking force BPth. After the commanded braking force BPTr reaches the stop-maintaining braking force BPth, the processing circuit 51 holds the commanded braking force BPTr at the stop-maintaining braking force BPth.

[0062] In the present embodiment, in the reduction correction process, the processing circuit 51 sets the front-wheel frictional braking force command value BPFFTr and the rear-wheel frictional braking force command value BPFRTr based on the commanded braking force BPTr and the target distribution ratio αd. Then, the processing circuit 51 operates the braking actuator 30 based on the front-wheel frictional braking force command value BPFFTr and the rear-wheel frictional braking force command value BPFRTr.

[0063] In the next step S27, the processing circuit 51 determines whether the transition condition from the subtraction correction process to the degradation process is satisfied. For example, if it can be determined that the vehicle 10 has stopped, it is considered that the transition condition from the subtraction correction process to the degradation process is satisfied. If it can be determined that the vehicle 10 has not stopped, it is considered that the transition condition from the subtraction correction process to the degradation process is not satisfied. When the processing circuit 51 determines that the transition condition is not satisfied (S27: NO), the process proceeds to step S25. That is, the processing circuit 51 executes the subtraction correction process. On the other hand, when the processing circuit 51 determines that the transition condition is satisfied (S27: YES), the process proceeds to step S29.

[0064] In step S29, the processing circuit 51 executes the degradation process. In the degradation process, the processing circuit 51 increases the indicated braking force BPTr to the required braking force BPRq. The processing circuit 51 gradually approaches the target distribution ratio αd to the reference distribution ratio αdb. The processing circuit 51 sets the front-wheel frictional braking force indication value BPFFTr and the rear-wheel frictional braking force indication value BPFRTr based on the indicated braking force BPTr and the target distribution ratio αd. Then, the processing circuit 51 operates the brake actuator 30 based on the front-wheel frictional braking force indication value BPFFTr and the rear-wheel frictional braking force indication value BPFRTr.

[0065] In the next step S31, the processing circuit 51 determines whether the end condition of the degradation process is satisfied. For example, when the indicated braking force BPTr becomes equal to the required braking force BPRq, it is considered that the end condition is satisfied. On the other hand, when the indicated braking force BPTr is less than the required braking force BPRq, it is considered that the end condition is not satisfied. When the processing circuit 51 determines that the end condition is not satisfied (S31: NO), the process proceeds to step S29. That is, the processing circuit 51 executes the degradation process. On the other hand, when the processing circuit 51 determines that the end condition is satisfied (S31: YES), the degradation process ends. Then, the processing circuit 51 ends the first stop-time braking control and ends the series of processes shown in FIG. 4.

[0066] In step S41, the processing circuit 51 sets a specified distribution ratio αdc as the target distribution ratio αd. In the next step S43, the processing circuit 51 determines whether or not the start condition for the braking control at stop is satisfied, in the same manner as in step S17 above. When the processing circuit 51 determines that the start condition is satisfied (S43: YES), the process proceeds to step S50. On the other hand, when the processing circuit 51 determines that the start condition is not satisfied (S43: NO), the series of processes shown in FIG. 4 is temporarily terminated.

[0067] In step S50, the processing circuit 51 performs a second braking control at stop as the braking control at stop. The second braking control at stop is a braking control at stop for stopping the vehicle 10 on a horizontal road.

[0068] Specifically, in step S51, the processing circuit 51 executes a supplementary correction process in the same manner as in step S21 above. In the subsequent step S53, the processing circuit 51 determines whether or not the transition condition from the supplementary correction process to the subtractive correction process is satisfied, in the same manner as in step S23 above. When the processing circuit 51 determines that the transition condition is not satisfied (S53: NO), the process proceeds to step S51. That is, the processing circuit 51 executes the supplementary correction process. On the other hand, when the processing circuit 51 determines that the transition condition is satisfied (S53: YES), the process proceeds to step S55.

[0069] In step S55, the processing circuit 51 executes the subtractive correction process of the second braking control at stop. In the subtractive correction process, the processing circuit 51 decreases the commanded braking force BPTr to the stop maintenance braking force BPth. After the commanded braking force BPTr reaches the stop maintenance braking force BPth, the processing circuit 51 holds the commanded braking force BPTr at the stop maintenance braking force BPth.

[0070] In this embodiment, in the subtraction correction process, the processing circuit 51 sets the front-wheel frictional braking force instruction value BPFFTr and the rear-wheel frictional braking force instruction value BPFRTr based on the instructed braking force BPTr and the target distribution ratio αd (i.e., the specified distribution ratio αdc). Then, the processing circuit 51 operates the braking actuator 30 based on the front-wheel frictional braking force instruction value BPFFTr and the rear-wheel frictional braking force instruction value BPFRTr.

[0071] In the next step S57, the processing circuit 51 determines, in the same manner as in step S27 above, whether the transition condition from the subtraction correction process to the degradation process is satisfied. If the processing circuit 51 determines that the transition condition is not satisfied (S57: NO), the process proceeds to step S55. That is, the processing circuit 51 executes the subtraction correction process. On the other hand, if the processing circuit 51 determines that the transition condition is satisfied (S57: YES), the process proceeds to step S59.

[0072] In step S59, the processing circuit 51 executes the degradation process in the same manner as in step S29 above. In the next step S61, the processing circuit 51 determines, in the same manner as in step S31 above, whether the end condition of the degradation process is satisfied. If the processing circuit 51 determines that the end condition is not satisfied (S61: NO), the process proceeds to step S59. That is, the processing circuit 51 executes the degradation process. On the other hand, if the processing circuit 51 determines that the end condition is satisfied (S61: YES), the degradation process ends. Then, the processing circuit 51 ends the second stop-time braking control and ends the series of processes shown in FIG. 4.

[0073] In this embodiment, the process of step S11 is executed by the processing circuit 51 functioning as the gradient acquisition unit M13. The processes of steps S13, S15, and S41 are executed by the processing circuit 51 functioning as the setting unit M15. Steps S20 and S50 are executed by the processing circuit 51 functioning as the control unit M11.

[0074] <Actions and Effects of this Embodiment> Referring to FIG. 5, the operation and effect when stopping the vehicle 10 on a slope will be described. As shown in FIGS. 5(A), 5(B), and 5(C), at the timing t21 when the driver performs a braking operation and braking force is being applied to the vehicle 10, the processing circuit 51 starts the supplementary correction process for the first stop-time braking control. Therefore, the vehicle braking force BPAl becomes greater than the required braking force BPRq.

[0075] Since the processing circuit 51 has determined that the traveling road surface of the vehicle 10 is a slope, the target distribution ratio αd is set such that the rear-wheel frictional braking force instruction value BPFRTr becomes smaller compared to the case where the traveling road surface is not a slope. In the example shown in FIG. 5, as the target distribution ratio αd, a distribution ratio equal to the reference distribution ratio αdb is set. The fact that the target distribution ratio αd is equal to the reference distribution ratio αdb is just an example. The target distribution ratio αd may be a distribution ratio different from the reference distribution ratio αdb as long as it makes the rear-wheel frictional braking force BPFR smaller than the specified distribution ratio αdc.

[0076] The processing circuit 51 sets the front-wheel frictional braking force instruction value BPFFTr and the rear-wheel frictional braking force instruction value BPFRTr based on the instructed braking force BPTr and the above target distribution ratio αd. Then, the processing circuit 51 controls the braking actuator 30 based on the front-wheel frictional braking force instruction value BPFFTr and the rear-wheel frictional braking force instruction value BPFRTr.

[0077] As a result, compared with the case where the specified distribution ratio αdc is set as the target distribution ratio αd, since the rear-wheel frictional braking force BPFR becomes smaller, an increase in the pitching suppression force is suppressed. As a result, just before stopping the vehicle 10 on a slope, an increase in the pitch angle θ of the vehicle 10 is suppressed. Thereby, just before the vehicle 10 stops, an upward movement of the line of sight of the occupant is suppressed. That is, the occupant does not visually feel that the deceleration of the vehicle 10 has become smaller. Therefore, when the traveling road surface is a downhill slope, the occupant's feeling that the vehicle 10 cannot be stopped on the downhill slope is suppressed.

[0078] Therefore, when the braking control device 50 stops the vehicle 10 on a downhill road by applying braking force, it can suppress the occurrence of a deviation between the behavior of the vehicle 10 felt by the occupant and the actual behavior of the vehicle 10.

[0079] In the present embodiment, the following effects can be further obtained. (1-1) The greater the magnitude of the road surface gradient η, the more likely it is that the occupant will visually feel that the deceleration of the vehicle 10 becomes smaller immediately before stopping, which is likely to make the occupant feel uncomfortable. In this regard, when the stop-time braking control is implemented on a slope road, the braking control device 50 sets the target distribution ratio αd such that the rear-wheel frictional braking force BPFR becomes smaller as the magnitude of the road surface gradient η becomes larger. Thereby, when the braking control device 50 stops the vehicle on a slope road with a relatively large magnitude of the road surface gradient η, it can enhance the suppression effect of visually feeling that the deceleration of the vehicle 10 becomes smaller.

[0080] (1-2) The stop-time braking control includes a deceleration correction process. Therefore, when stopping the vehicle 10 on a slope road, by implementing the stop-time braking control, the braking control device 50 can suppress the occurrence of a deviation between the behavior of the vehicle 10 felt by the occupant and the actual behavior of the vehicle 10, and can also suppress the change in the posture of the vehicle 10 at the time of stopping.

[0081] (Second Embodiment) A second embodiment of the braking control device will be described with reference to FIG. 6. Note that in the second embodiment, it is different from the first embodiment in that the vehicle can be provided with a regenerative braking force. In the following description, the parts different from the first embodiment will be mainly described, and the same reference numerals will be given to the same member configurations as those in the first embodiment, and the redundant description will be omitted.

[0082] As shown in FIG. 6, the vehicle 10A further includes a regenerative device 60. For example, the regenerative device 60 is configured to be able to apply a regenerative braking force to the front wheels 12 among a plurality of wheels. The regenerative braking force applied to the front wheels 12 is referred to as "front-wheel regenerative braking force BPEF". The regenerative device 60 has a motor generator 61 and a regenerative control device 62. The regenerative control device 62 is an electronic control device that operates the motor generator 61. The regenerative control device 62 controls the front-wheel regenerative braking force BPEF by causing the motor generator 61 to function as a generator.

[0083] Here, the front-wheel frictional braking force BPFF acts on the first acting point PA1 which is the contact point between the front wheels 12 and the road surface 100 as shown in FIG. 2. On the other hand, the front-wheel regenerative braking force BPEF acts on the rotation center of the front wheels 12. Therefore, the magnitude of the anti-dive force FAD generated by applying the front-wheel regenerative braking force BPEF to the front wheels 12 is different from the magnitude of the anti-dive force FAD generated by applying the front-wheel frictional braking force BPFF to the front wheels 12. Specifically, the front-wheel regenerative braking force BPEF is a braking force that is less likely to increase the anti-dive force FAD compared to the front-wheel frictional braking force BPFF.

[0084] Therefore, by changing the distribution ratio between the front-wheel frictional braking force BPFF and the front-wheel regenerative braking force BPEF, the anti-dive force FAD and the pitching suppression force change. Specifically, by changing the distribution ratio between the front-wheel frictional braking force BPFF and the front-wheel regenerative braking force BPEF to a distribution ratio in which the front-wheel frictional braking force BPFF becomes smaller, the anti-dive force FAD and the pitching suppression force become smaller. As a result, the pitch angle θ during vehicle braking is likely to increase.

[0085] That is, when the front-wheel regenerative braking force BPEF is the first braking force, the front-wheel frictional braking force BPFF corresponds to the second braking force. In this case, the regenerative device 60 corresponds to the first control unit, and the friction brake 20A for the front wheels corresponds to the second braking unit.

[0086] <Brake control device> When the vehicle is braking, the processing circuit 51A of the braking control device 50A adjusts both the frictional braking force and the regenerative braking force. When the distribution ratio between the front-wheel frictional braking force BPFF and the front-wheel regenerative braking force BPEF is defined as the front-wheel distribution ratio αfd, the processing circuit 51A functions as a control unit to perform stop-time braking control for changing the front-wheel distribution ratio αfd so that the front-wheel frictional braking force BPFF increases.

[0087] Specifically, based on the commanded braking force BPTr and the front-wheel distribution ratio αfd, the processing circuit 51A derives a rear-wheel frictional braking force command value BPFRTr, a front-wheel frictional braking force command value BPFFTr, and a front-wheel regenerative braking force command value BPEFTr. The front-wheel regenerative braking force command value BPEFTr is a command value for the front-wheel regenerative braking force BPEF. The processing circuit 51A operates the brake actuator 30 based on the rear-wheel frictional braking force command value BPFRTr and the front-wheel frictional braking force command value BPFFTr. Also, the processing circuit 51A transmits the front-wheel regenerative braking force command value BPEFTr to the regenerative control device 62 of the regenerator 60.

[0088] When the regenerative control device 62 receives the front-wheel regenerative braking force command value BPEFTr, it operates the motor generator 61 so that the front-wheel regenerative braking force BPEF becomes the front-wheel regenerative braking force command value BPEFTr.

[0089] When the running road surface of the vehicle 10A is a slope, the processing circuit 51 functions as a setting unit to set the front-wheel distribution ratio αfd so as to suppress an increase in the front-wheel frictional braking force BPFF as compared with the case where the running road surface is not a slope.

[0090] Note that when the running road surface of the vehicle 10A is a slope, the processing circuit 51A may vary the front-wheel distribution ratio αfd according to the road surface gradient η. <Actions and Effects of this Embodiment> When the processing circuit 51 of the braking control device 50A stops the vehicle 10 on a slope road, it performs the first stop-time braking control. In this case, the processing circuit 51 sets the front-wheel distribution ratio αfd to a ratio that reduces the front-wheel frictional braking force BPFF, as compared with the case of performing the second stop-time braking control. As a result, it is possible to suppress an increase in the pitching suppression force before the vehicle 10 stops. As a result, immediately before stopping the vehicle 10 on a slope road, it is possible to suppress a decrease in the pitch angle θ of the vehicle 10. Thereby, immediately before the vehicle 10 stops, it is possible to suppress the line of sight of the occupant from moving upward. That is, the occupant does not visually feel that the deceleration of the vehicle 10 has decreased. Therefore, when the driving road surface is a downhill road, it is possible to suppress the occupant from feeling that the vehicle 10 cannot be stopped on the downhill road.

[0091] Therefore, when the braking control device 50A stops the vehicle 10 on a downhill road by applying braking force, it is possible to suppress a deviation from occurring between the behavior of the vehicle 10 felt by the occupant and the actual behavior of the vehicle 10.

[0092] In addition, the braking control device 50A can obtain the same effects as the effects (1-1) and (1-2) of the first embodiment. (Modification example) The above-described plurality of embodiments can be implemented with the following modifications. The above-described plurality of embodiments and the following modification examples can be implemented in combination with each other within a technically non-conflicting range.

[0093] ·In the second embodiment, the vehicle 10A may be configured to include a rear-wheel regeneration device that can apply a rear-wheel regenerative braking force BPER to the rear wheels 13. In this case, when the braking control device 50A stops the vehicle 10A on a slope road, it is preferable to change the distribution ratio between the rear-wheel frictional braking force BPFR and the rear-wheel regenerative braking force BPER in the stop-time braking control to a ratio that suppresses an increase in the rear-wheel frictional braking force BPFR. As a result, the anti-lift force FAL can be reduced, and thus the pitching suppression force is reduced. Therefore, the braking control device 50A can obtain the same operations and effects as those of the second embodiment.

[0094] · In the second embodiment, if the braking control device 50A changes the front wheel distribution ratio αfd according to the magnitude of the road surface gradient η in the first stop braking control, the target distribution ratio αd may be held at the reference distribution ratio αdb.

[0095] · In the above-described multiple embodiments, when stopping the vehicles 10, 10A on an uphill road, the braking control devices 50, 50A performed the first stop braking control, but it is not limited thereto. For example, when stopping the vehicles 10, 10A on an uphill road, the braking control devices 50, 50A may perform the second stop braking control.

[0096] · In the above-described multiple embodiments, in the degradation process of the first stop braking control, it is preferable to make the increasing speed of the indicated braking force BPTr larger than that at the time of executing the degradation process of the second stop braking control.

[0097] · If the stop braking control includes the subtraction correction process and the degradation process, it may not include the addition correction process. · The predetermined braking force may be a value different from the stop maintaining braking force BPth. For example, a vehicle braking force BPAl slightly larger than the stop maintaining braking force BPth may be set as the predetermined braking force.

[0098] · If the stop braking control changes the target distribution ratio αd, the indicated braking force BPTr may be continuously held at the required braking force BPRq. · As the target distribution ratio αd during the execution of the first stop braking control, if a distribution ratio that suppresses an increase in the rear wheel frictional braking force BPFR can be set as compared with the case where the traveling road surface is not a slope road, the target distribution ratio αd may not be varied according to the magnitude of the road surface gradient η.

[0099] · As the front wheel distribution ratio αfd during the execution of the first stop braking control, if a distribution ratio that suppresses an increase in the front wheel frictional braking force BPFF can be set as compared with the case where the traveling road surface is not a slope road, the front wheel distribution ratio αfd may not be varied according to the magnitude of the road surface gradient η.

[0100] · In the above-described multiple embodiments, the processing circuits 51 and 51A determine the start timing of the supplementary correction process and the start timing of the reduction correction process for the stop-time braking control in accordance with the change in the vehicle body speed VS. However, if it is a parameter whose value decreases as the vehicle 10 approaches the stop position PS, the processing circuits 51 and 51A may determine the start timing of each process using other parameters than the vehicle body speed VS. Examples of other parameters include, for example, the stop distance and the stop prediction time. The stop distance is the distance from the current position of the vehicle 10 to the stop position PS. The stop prediction time is the time required for the vehicle 10 to stop. An example of the stop prediction time is TTC. TTC is an abbreviation of "Time To Collision".

[0101] · In the above-described multiple embodiments, the processing circuits 51 and 51A execute the stop-time braking control during vehicle braking accompanied by the operation of the braking operation member 11 by the driver. However, the processing circuits 51 and 51A may perform the stop-time braking control during automatic braking.

[0102] · The processing circuits 51 and 51A can be configured as a circuit including one or more processors that operate according to a computer program, one or more dedicated hardware circuits such as dedicated hardware for executing at least a part of various processes, or a combination thereof. Examples of the dedicated hardware include, for example, an ASIC (Application Specific Integrated Circuit) which is an integrated circuit for a specific purpose. The processor includes a CPU and a memory such as a RAM and a ROM, and the memory stores program codes or instructions configured to cause the CPU to execute processes. The memory, that is, the storage medium, includes any available medium that can be accessed by a general-purpose or dedicated computer.

[0103] · The vehicle to which the braking control device is applied may be a vehicle in which the pitching behavior of the vehicle 10 in the pitching direction associated with the application of a desired amount of rear-wheel frictional braking force BPFR to the vehicle 10 is different from the pitching behavior of the vehicle 10 in the pitching direction associated with the application of a desired amount of front-wheel frictional braking force BPFF to the vehicle 10. Specifically, the vehicle 10 may be configured such that the larger the ratio of the front-wheel frictional braking force BPFF in the total braking force, which is the sum of the front-wheel frictional braking force BPFF and the rear-wheel frictional braking force BPFR, the more the attitude change of the vehicle 10 can be suppressed. In this case, the rear-wheel frictional braking force BPFR corresponds to the first braking force, and the front-wheel frictional braking force BPFF corresponds to the second braking force. Also, the friction brake 20B for the rear wheels corresponds to the first braking part, and the friction brake 20A for the front wheels corresponds to the second braking part.

[0104] <Other technical ideas> The technical ideas that can be grasped from the above-described plurality of embodiments and modification examples will be described. [Appendix 1] It is preferable that the stop-time braking control includes a deceleration correction process of reducing the total braking force to a predetermined braking force smaller than the required value of the total braking force, which is the sum of the first braking force and the second braking force, and then setting the vehicle body speed of the vehicle to 0 (zero).

[0105] [Appendix 2] The stop-time braking control includes a retraction process of increasing the braking force applied to the vehicle after the execution of the deceleration correction process. When the traveling road surface is an uphill road, the setting unit preferably sets the distribution ratio at the time of executing the deceleration correction process so as to suppress an increase in the second braking force as compared with the case where the traveling road surface is not a slope road.

[0106] [Appendix 3] Applied to the vehicle in which the braking force applied to the vehicle can be distributed to the front-wheel braking force, which is the braking force applied to the front wheels of the vehicle, and the rear-wheel braking force, which is the braking force applied to the rear wheels of the vehicle. When applying braking force to the vehicle to stop it, a control unit that executes stop-time braking control for changing the distribution ratio between the front-wheel braking force and the rear-wheel braking force before stopping so that the rear-wheel braking force increases. When the road surface on which the vehicle travels is a downhill road, a setting unit that sets the distribution ratio at the time of executing the stop-time braking control so as to suppress an increase in the rear-wheel braking force as compared with the case where the traveling road surface is not a downhill road. A braking control device comprising:

[0107] Note that the expression "at least one" used in this specification means "one or more" of the desired options. As an example, the expression "at least one" used in this specification means "only one option" or "both of the two options" if the number of options is two. As another example, the expression "at least one" used in this specification means "only one option" or "any combination of two or more options" if the number of options is three or more.

Explanation of Reference Numerals

[0108] 10, 10A... Vehicle 12... Front wheels 13... Rear wheels 20A, 20B... Friction brakes (an example of a braking unit) 30... Braking actuator 50, 50A... Braking control device 51, 51A... Processing circuit 60... Regenerative device (an example of a braking unit) 61... Motor generator 100... Traveling road surface M11... Control unit M13... Gradient acquisition unit M15... Setting unit

Claims

1. A vehicle is provided with a first braking part for applying a first braking force to the vehicle and a second braking part for applying a second braking force to the vehicle. When the first braking part applies the first braking force to the vehicle, the change in attitude at the pitch on the nose dive side given to the vehicle is greater than the change in attitude given to the vehicle when the second braking part applies the second braking force of the same magnitude to the vehicle. This is applied to the vehicle, When braking the vehicle to a stop, a control unit that performs stop-time braking control for changing the distribution ratio of the first braking force and the second braking force so that the second braking force increases before the vehicle stops, When the traveling road surface of the vehicle is a downhill road, a setting unit that sets the distribution ratio during the execution of the stop-time braking control to suppress an increase in the second braking force as compared with the case where the traveling road surface is not a downhill road. The braking control device is provided with A braking control device.

2. It is provided with a gradient acquisition unit for acquiring the gradient of the traveling road surface, When the traveling road surface is a downhill road, the setting unit sets the distribution ratio during the execution of the stop-time braking control so that the increase in the second braking force is more strongly suppressed as the gradient of the traveling road surface is greater. The braking control device according to claim 1.

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