Brake control device

Abstract

A brake control device (50) functions as a parking correlation value acquisition unit (M15) that acquires a parking correlation value that becomes smaller as a vehicle (10) approaches a predetermined stop position, a control unit (M19) that starts stop-time brake control when the parking correlation value becomes equal to or less than a threshold value, and a threshold value setting unit (M17) that sets the threshold value of the vehicle (10) when the parking correlation value becomes equal to or less than the threshold value. And a threshold value setting unit (M17) that sets the threshold value to a smaller value as the parking-related value becomes smaller before the start of the stop-time brake control, the stop-time brake control being a brake control for stopping the vehicle (10) in a state in which the braking force given to the vehicle (10) is made smaller than the required braking force, and the threshold value setting unit (M17) being a threshold value that becomes smaller as the parking-related value becomes smaller before the start of the stop-time brake control.

Description

TECHNICAL FIELD

[0001] The present application relates to a brake control device that controls a brake force given to a vehicle in a case where a brake request for the vehicle is generated. BACKGROUND

[0002] Patent Document 1 discloses a control device that executes brake control that suppresses a rapid change in a pitch attitude of a vehicle accompanying a stop. If a vehicle speed becomes a prescribed speed or less, the control device controls a motor generator so as to reduce a regenerative brake force toward 0 (zero). Also, if the vehicle speed becomes 0 (zero), the control device increases a friction brake force by operating a hydraulic actuator.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2016-28913

[0004] In a traffic jam, low-speed travel of a vehicle and a stop accompanying a vehicle brake are sometimes repeated. If a brake force is given to a vehicle that is traveling at a low speed, the vehicle stops immediately. In other words, there is a concern that the vehicle stops before the above-described brake control is started. In such a case, a rapid change in a pitch attitude of the vehicle accompanying a stop cannot be suppressed. SUMMARY

[0005] A brake control device for solving the above-described problem is provided with: a stop-related value acquisition section that acquires a stop-related value that becomes smaller as a vehicle approaches a prescribed stop position; a control section that starts a stop-time brake control in a case where the above-described stop-related value becomes a prescribed threshold value or less, the stop-time brake control being brake control that stops the above-described vehicle in a state where a brake force given to the above-described vehicle is smaller than a required value of the brake force given to the above-described vehicle, that is, a required brake force; and a threshold value setting section that sets the above-described threshold value to a smaller value as the above-described stop-related value is smaller before the start of the above-described stop-time brake control.

[0006] The above-described brake control device achieves an effect that a rapid change in a pitch attitude of a vehicle accompanying a stop can be suppressed even in a case where a brake request is generated for a vehicle that is traveling at a low speed. BRIEF DESCRIPTION OF DRAWINGS

[0007] Figure 1 is a schematic configuration view of a vehicle that is provided with a brake control device of an embodiment.

[0008] Figure 2 is a timing chart in a case where a stop-time brake control is executed.

[0009] Figure 3 is a map that shows a relationship between a base value of a first vehicle body speed determination value and a vehicle body speed.

[0010] Figure 4It means by Figure 1 The flowchart shows a series of processes performed by the braking control device.

[0011] Figure 5 Is Figure 1 The timing diagram shows the braking control device when braking control is executed during a stop.

[0012] Figure 6 This is a timing diagram of the braking control device in the modified example, where braking control is performed when stopping. Detailed Implementation

[0013] The following is based on Figures 1-5 One embodiment of the braking control device will be described.

[0014] Figure 1 The illustration shows a vehicle 10 equipped with a brake control device 50. The vehicle 10 includes a brake operating component 11, multiple wheels, multiple friction brakes 20, and a braking device 30. The brake operating component 11 is operated by the driver when braking force is applied to the vehicle 10. An example of the brake operating component 11 is a brake pedal. The multiple wheels include two front wheels 12 and two rear wheels 13.

[0015] <Friction Brake>

[0016] Multiple friction brakes 20 apply braking force to their respective wheels. Each friction brake 20 has a wheel cylinder 21, a rotating body 22, and a friction part 23. The rotating body 22 rotates integrally with the wheel, so braking force is applied to the wheel by pressing the friction part 23 against the rotating body 22. The higher the hydraulic pressure in the wheel cylinder 21, the greater the force that presses the friction part 23 against the rotating body 22. Therefore, the higher the hydraulic pressure in the wheel cylinder, the greater the braking force that the friction brake 20 can apply to the wheel.

[0017] <Brake Device>

[0018] The braking device 30 controls the braking force applied to the wheels 12 and 13 by controlling the hydraulic pressure of the multiple wheel cylinders 21. For example, the braking device 30 has a pressurization source that supplies brake fluid to the multiple wheel cylinders 21. The pressurization source is, for example, an electric pump and an electric cylinder. The braking device 30 can independently adjust the hydraulic pressure of the wheel cylinders 21 for the front wheel 12 and the wheel cylinders 21 for the rear wheel 13.

[0019] In the following description, the sum of the braking forces applied to multiple wheels 12 and 13 will also be referred to as "the braking force applied to vehicle 10 BPA1".

[0020] <Detection System>

[0021] The detection system inputs a detection signal to the brake control device 50. The detection system has multiple sensors, including a brake sensor 101, front and rear acceleration sensors 102, and multiple wheel speed sensors 103.

[0022] Brake sensor 101 detects information related to the driver's operation of brake operating component 11. An example of brake sensor 101 is a stroke sensor that detects the amount of operation by the driver on brake operating component 11. The amount of operation based on the detection signal from brake sensor 101 is referred to as "operation amount X". Alternatively, the detection system may also include a sensor that detects the force applied by the driver to brake operating component 11.

[0023] The front and rear acceleration sensors 102 detect the acceleration of the vehicle 10 in the front-rear direction, which is part of the acceleration applied to the vehicle 10. The front-rear acceleration of the vehicle 10 based on the detection signal of the front and rear acceleration sensors 102 is called "front-rear acceleration Gx".

[0024] Wheel speed sensors 103 are installed for each of the multiple wheels. The multiple wheel speed sensors 103 detect the rotational speed of the corresponding wheel. The rotational speed of the wheel based on the detection signal of the wheel speed sensor 103 is called "wheel speed VW".

[0025] <Brake Control Device>

[0026] The braking 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 and a memory 53. The memory 53 stores the control program executed by the CPU 52. By executing this control program by the CPU 52, the processing circuit 51 controls the braking device 30 to activate multiple friction brakes 20. That is, by activating the multiple friction brakes 20, the processing circuit 51 can adjust the braking force BPA1 applied to the vehicle 10.

[0027] <Overview of braking control during stop>

[0028] The processing circuit 51 performs stop-time braking control when the driver operates the brake operation component 11. Stop-time braking control is a braking control that stops the vehicle 10 while ensuring that the braking force BPA1 applied to the vehicle 10 is less than the required braking force BPRq. The required braking force BPRq refers to the required value of the braking force BPA1 applied to the vehicle 10.

[0029] Reference Figure 2 The braking control during stopping is explained.

[0030] At time t11, while the vehicle 10 is in motion, the driver begins to operate the braking control component 11. In this situation, as... Figure 2As shown in (B), the processing circuit 51 derives the required braking force BPRq. For example, the processing circuit 51 derives the required braking force BPRq in such a way that the larger the operation amount X of the braking operation component 11, the larger its value. In the case where, as before time t12, the vehicle speed VS of the vehicle 10 is greater than the first vehicle speed determination value VSth1, such as... Figure 2 As shown in (D), the processing circuit 51 sets the required braking force BPRq as the indicated braking force BPTr. Furthermore, the processing circuit 51 controls the braking device 30 so that the braking force BPA1 applied to the vehicle 10 becomes the indicated braking force BPTr. Additionally, the vehicle speed VS is the vehicle 10's moving speed derived from the wheel speed VW.

[0031] If a braking force of 10 BPA1 is applied to the vehicle like this, then... Figure 2 As shown in (A), the vehicle speed VS decreases. Additionally, as... Figure 2 As shown in (C), the absolute value of the front and rear acceleration Gx increases with the increase of the braking force BPA1.

[0032] If, at time t12, the vehicle speed VS becomes the first vehicle speed determination value VSth1, then the processing circuit 51 begins braking control during stop. The first vehicle speed determination value VSth1 is a threshold used to set the start time of braking control during stop. From time t12, the processing circuit 51 begins an increase correction process for braking control during stop. In the increase correction process, the processing circuit 51 sets a braking force greater than the required braking force BPRq as the indicated 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 indicated braking force BPTr. Moreover, the processing circuit 51 controls the braking device 30 so that the braking force BPA1 applied to the vehicle 10 becomes this indicated braking force BPTr. Thus, even if the required braking force BPRq is the same, the absolute value of the vehicle 10's front-rear acceleration Gx increases by an amount corresponding to the offset value ΔBP compared to before time t12.

[0033] At time t13, the vehicle speed VS becomes the second vehicle speed determination value VSth2. A vehicle speed smaller than the first vehicle speed determination value VSth1 is set as the second vehicle speed determination value VSth2. When the vehicle speed VS is below the second vehicle speed determination value VSth2, the vehicle 10 is considered to be approaching the stopping position PS. The stopping position PS refers to the predicted stopping position of the vehicle 10. The processing circuit 51 switches the braking control processing at the time of stopping from an increase correction process to a decrease correction process. In the decrease correction process, the processing circuit 51 reduces the indicated braking force BPTr at a constant speed. Furthermore, the processing circuit 51 controls the braking device 30 so that the braking force BPA1 applied to the vehicle 10 becomes the indicated braking force BPTr. By performing the decrease correction process by the processing circuit 51 in this way, the braking force BPA1 is 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 vehicle 10's front-to-rear acceleration Gx gradually decreases.

[0034] At time t14, the indicated braking force BPTr is equal to the parking holding braking force BPth. The parking holding braking force BPth is set as the minimum braking force required to keep the vehicle 10 at a stop on the current road surface, or a braking force slightly greater than this. At time t14, during the reduction correction process, the processing circuit 51 maintains the indicated braking force BPTr at the parking holding braking force BPth.

[0035] At time t15, processing circuit 51 determines that vehicle 10 has stopped, so it switches the braking control process from reduction correction to retraction. In the retraction process, processing circuit 51 increases the indicated braking force BPTr. For example, processing circuit 51 increases the indicated braking force BPTr to the required braking force BPRq. Based on the indicated braking force BPTr, processing circuit 51 controls the braking device 30, thereby increasing the braking force BPA1 applied to vehicle 10. If at time t16, the indicated braking force BPTr equals the required braking force BPRq, then processing circuit 51 terminates the braking control at stop.

[0036] <Functional Department>

[0037] Reference Figure 1 as well as Figure 3 The functional configuration of the braking control device 50 will be explained.

[0038] like Figure 1 As shown, the processing circuit 51 functions as the braking force output unit M11, the stop position setting unit M13, the parking related value acquisition unit M15, the threshold setting unit M17, and the control unit M19 by the CPU 52 executing the control program of the memory 53.

[0039] The braking force output unit M11 is required to output the required braking force BPRq in such a way that the larger the operation amount X of the braking operation component 11, the larger the value of the required braking force BPRq.

[0040] When the vehicle 10 decelerates due to the application of braking force, the stop position setting unit M13 sets the target position for stopping the vehicle 10 as the stop position PS. For example, the stop position setting unit M13 derives the stop position PS based on the vehicle 10's body speed VS and deceleration DVS. Deceleration DVS is the deceleration related to the braking force BPA1 applied to the vehicle 10. For example, deceleration DVS can be derived by performing a time derivative on the body speed VS and reversing the sign of its calculated value. Therefore, if the vehicle 10 decelerates, deceleration DVS becomes a positive value. Furthermore, the stop position setting unit M13 derives the stopping position of the vehicle 10 that can be predicted based on the body speed VS and deceleration DVS as the stop position PS. Specifically, the smaller the body speed VS, the closer the stop position setting unit M13 will be to the current position of the vehicle 10 as the stop position PS. Conversely, the larger the deceleration DVS, the closer the stop position setting unit M13 will be to the current position of the vehicle 10 as the stop position PS.

[0041] The parking-related value acquisition unit M15 acquires a parking-related value that decreases as the vehicle 10 approaches the stop position PS. For example, the parking-related value acquisition unit M15 acquires a parking-related value when the vehicle 10 decelerates due to the application of braking force. In this embodiment, the parking-related value acquisition unit M15 acquires the vehicle body speed VS of the vehicle 10 as the parking-related value. The parking-related value can also be described as a parameter whose value gradually decreases over time when the vehicle 10 decelerates due to the application of braking force BPA1.

[0042] The threshold setting unit M17 sets a first vehicle speed determination value VSth1, which is a threshold for determining the start time of braking control during a stop. Before the start of braking control during a stop, the smaller the vehicle speed VS obtained by the parking-related value acquisition unit M15, the smaller the first vehicle speed determination value VSth1 will be set by the threshold setting unit M17. At this time, the threshold setting unit M17 sets a vehicle speed smaller than the vehicle speed VS at the setting time of the first vehicle speed determination value VSth1 as the first vehicle speed determination value VSth1.

[0043] In this embodiment, the threshold setting unit M17 sets the second vehicle speed determination value VSth2 at the same time as setting the first vehicle speed determination value VSth1. Specifically, the smaller the vehicle speed VS obtained by the parking-related value acquisition unit M15, the smaller the second vehicle speed determination value VSth2 will be set by the threshold setting unit M17.

[0044] When a braking request is generated for vehicle 10, the threshold setting unit M17 sets a first vehicle speed determination value VSth1 and a second vehicle speed determination value VSth2. That is, the smaller the vehicle speed VS at the moment the braking request is generated, the smaller the first vehicle speed determination value VSth1 is set by the threshold setting unit M17. Similarly, the smaller the vehicle speed VS at the moment the braking request is generated, the smaller the second vehicle speed determination value VSth2 is set by the threshold setting unit M17.

[0045] The threshold setting unit M17 sets the first vehicle speed determination value VSth1 and the second vehicle speed determination value VSth2 based not only on the vehicle speed VS but also on the vehicle deceleration DVS of the vehicle 10. For example, the threshold setting unit M17 sets the first vehicle speed determination value VSth1 in such a way that the larger the deceleration DVS at the moment of braking demand, the smaller the value of the first vehicle speed determination value VSth1. Similarly, the threshold setting unit M17 sets the second vehicle speed determination value VSth2 in such a way that the larger the deceleration DVS at the moment of braking demand, the smaller the value of the second vehicle speed determination value VSth2.

[0046] Here, refer to Figure 3 Here is an example of setting the first vehicle speed determination value VSth1. Figure 3 This is a mapping diagram showing the relationship between the base value VSth1A of the first vehicle speed determination value VSth1 and the vehicle speed VS. For example... Figure 3 As shown, when the vehicle speed VS is greater than or equal to the first vehicle speed VS1, the threshold setting unit M17 sets the reference vehicle speed VSA to the base value VSth1A. For example, the criterion for determining whether the vehicle 10 is traveling at a low speed is set to the first vehicle speed VS1. On the other hand, when the vehicle speed VS is less than the first vehicle speed VS1, the threshold setting unit M17 sets the smaller the vehicle speed VS to the base value VSth1A.

[0047] Furthermore, the threshold setting unit M17 sets the reduction correction gain Gd based on the deceleration DVS of the vehicle 10. At this time, the threshold setting unit M17 sets the reduction correction gain Gd to a value that is greater than 0 (zero) and less than 1. For example, the larger the deceleration DVS, the smaller the value that the threshold setting unit M17 sets the reduction correction gain Gd to.

[0048] Furthermore, the threshold setting unit M17 sets the product of the base value VSth1A of the first vehicle speed determination value and the reduction correction gain Gd as the first vehicle speed determination value VSth1. Thus, the threshold setting unit M17 can set the first vehicle speed determination value VSth1 based on the vehicle speed VS and the deceleration DVS.

[0049] Furthermore, the threshold setting unit M17 can set the second vehicle speed determination value VSth2 using the same method as setting the first vehicle speed determination value VSth1.

[0050] The control unit M19 controls the operation of the braking device 30. Specifically, during vehicle braking, the control unit M19 initiates stop braking control when the vehicle speed VS falls below the first vehicle speed determination value VSth1.

[0051] <Procedure for handling vehicle braking>

[0052] Reference Figure 4 The following describes a series of processes performed by the processing circuit 51 during stop braking control. The processing circuit 51 repeatedly executes... Figure 4 The series of processes shown.

[0053] In step S11, the processing circuit 51 determines whether a braking request for the vehicle 10 has been generated. For example, if the processing circuit 51 detects that the driver operates the brake operating component 11, it determines that a braking request has been generated. The processing circuit 51 can detect the driver's operation of the brake operating component 11 based on the detection signal from the brake sensor 101. If the processing circuit 51 determines that a braking request has been generated (S11: Yes), it transfers the processing to step S13. On the other hand, if the processing circuit 51 determines that no braking request has been generated (S11: No), it temporarily terminates the series of processes.

[0054] In step S13, the processing circuit 51, acting as the required braking force output unit M11, outputs the required braking force BPRq. Next, in step S15, the processing circuit 51 determines whether a first vehicle speed determination value VSth1 has been set during this vehicle braking maneuver. If the processing circuit 51 determines that the first vehicle speed determination value VSth1 has been set (S15: Yes), the process proceeds to step S23. Conversely, if the processing circuit 51 determines that the first vehicle speed determination value VSth1 has not been set (S15: No), the process proceeds to step S17.

[0055] In step S17, the processing circuit 51 functions as a stop position setting unit M13 to set the stop position PS. At this time, the processing circuit 51 sets the stop position PS based on the vehicle speed VS and deceleration DVS at the moment the braking request is generated.

[0056] Next, in step S19, the processing circuit 51, through the parking-related value acquisition unit M15, acquires the vehicle speed VS at the current moment. Additionally, the processing circuit 51 acquires the vehicle deceleration DVS at the current moment.

[0057] In the next step S21, the processing circuit 51 functions as a threshold setting unit M17 to set a first vehicle speed determination value VSth1 and a second vehicle speed determination value VSth2. At this time, the processing circuit 51 sets the first vehicle speed determination value VSth1 and the second vehicle speed determination value VSth2 based on the vehicle speed VS and deceleration DVS obtained in step S19. Then, the processing circuit 51 transfers the processing to step S23.

[0058] In step S23, the processing circuit 51 operates as the parking-related value acquisition unit M15 to acquire the vehicle speed VS at that moment.

[0059] Then, in step S25, the processing circuit 51 determines whether the vehicle speed VS obtained in step S23 is below the first vehicle speed determination value VSth1. If the vehicle speed VS is below the first vehicle speed determination value VSth1 (S25: Yes), the processing circuit 51 transfers the processing to step S29. On the other hand, if the vehicle speed VS is greater than the first vehicle speed determination value VSth1 (S25: No), the processing circuit 51 transfers the processing to step S27.

[0060] In step S27, the processing circuit 51 performs normal braking control by functioning as the control unit M19. In normal braking control, the processing circuit 51 sets the required braking force BPRq derived in step S13 to the indicated braking force BPTr. Then, the processing circuit 51 controls the braking device 30 so that the braking force BPA1 becomes the indicated braking force BPTr. Afterward, the processing circuit 51 temporarily terminates a series of processes.

[0061] In step S29, the processing circuit 51 performs stop-time braking control by functioning as the control unit M19. During stop-time braking control, if the vehicle speed VS is greater than the second vehicle speed determination value VSth2, the processing circuit 51 performs an increase correction process. That is, the processing circuit 51 sets a braking force greater than the required braking force BPRq as the indicated braking force BPTr, and controls the braking device 30 based on this indicated braking force BPTr.

[0062] When the processing circuit 51 determines that the vehicle speed VS is below the second vehicle speed determination value VSth2 and the vehicle 10 has not stopped, it performs a reduction correction process. That is, the processing circuit 51 reduces the indicated braking force BPTr until the indicated braking force BPTr equals the parking holding braking force BPth. The processing circuit 51 can set the reduction rate of the indicated braking force BPTr at this time based on at least one of the vehicle speed VS and the deceleration DVS obtained in step S17. For example, the processing circuit 51 sets the reduction rate of the indicated braking force BPTr such that the smaller the vehicle speed VS obtained in step S17, the larger the value of the reduction rate of the indicated braking force BPTr. Alternatively, for example, the processing circuit 51 sets the reduction rate of the indicated braking force BPTr such that the larger the deceleration DVS obtained in step S17, the larger the value of the reduction rate of the indicated braking force BPTr. However, after the indicated braking force BPTr equals the parking holding braking force BPth, the processing circuit 51 maintains the indicated braking force BPTr at the parking holding braking force BPth. Then, the processing circuit 51 controls the braking device 30 based on the set indicated braking force BPTr.

[0063] When the processing circuit 51 determines that the vehicle 10 has stopped, it performs a retraction process. That is, the processing circuit 51 increases the indicated braking force BPTr to the required braking force BPRq. Then, the processing circuit 51 controls the braking device 30 based on the set indicated braking force BPTr. After that, the processing circuit 51 temporarily terminates a series of processes.

[0064] <Functions and Effects>

[0065] Reference Figure 5 This explains the function and effect of vehicle braking. Figure 5 middle, Figure 5 The solid line (D) represents the shift of the indicator braking force BPTr in this embodiment. Figure 5 The dashed line (D) represents the shift of the indicated braking force BPTRA in the comparative example. Additionally, in Figure 5 middle, Figure 5 The solid line (C) represents the shift of the forward and backward acceleration Gx in this embodiment. Figure 5 The dashed line (C) represents the forward and backward acceleration GxA shift in the comparative example. Furthermore, the comparative example is the case where braking control is not performed during stopping.

[0066] like Figure 5 As shown in (A), vehicle 10 is traveling at a speed VS that is less than the first speed VS1. At time t21, when vehicle 10 is traveling at such a low speed, the driver begins to operate the braking control component 11. Thus, as... Figure 5As shown in (B), the required braking force BPRq is derived in such a way that the larger the operating amount X of the braking operation component 11, the larger the value of the required braking force BPRq. The required braking force BPRq is set as the indicated braking force BPTr. Then, the braking device 30 operates based on the indicated braking force BPTr.

[0067] In this embodiment, if a braking requirement is generated in this manner, the first vehicle speed determination value VSth1 and the second vehicle speed determination value VSth2 are set such that the smaller the vehicle speed VS at that time, the smaller the values ​​of the first vehicle speed determination value VSth1 and the second vehicle speed determination value VSth2. Therefore, the first vehicle speed determination value VSth1 and the second vehicle speed determination value VSth2 are set to be smaller than the vehicle speed VS at time t21.

[0068] exist Figure 5 In the example shown, at time t22 during the process of the vehicle speed VS decreasing, the vehicle speed VS becomes the first vehicle speed determination value VSth1, so braking control at the time of stopping begins. During the period from time t22 to time t23, the vehicle speed VS is greater than the second vehicle speed determination value VSth2. Therefore, an increase correction process for braking control at the time of stopping is performed. In this case, the indicated braking force BPTr is set to a value greater than the required braking force BPRq, and the braking device 30 operates based on the indicated braking force BPTr.

[0069] At time t23 during the execution of the increase correction process, the vehicle speed VS becomes the second vehicle speed determination value VSth2, so the increase correction process ends and the decrease correction process begins. During the decrease correction process, the indicated braking force BPTr is reduced to the parking holding braking force BPth. Furthermore, the braking device 30 operates based on this indicated braking force BPTr. The parking holding braking force BPth is smaller than the required braking force BPRq. Therefore, by executing the decrease correction process, the braking force BPA1 becomes smaller than the required braking force BPRq.

[0070] At time t24, the indicated braking force BPTr becomes the parking holding braking force BPth, so the indicated braking force BPTr remains the parking holding braking force BPth.

[0071] Then at time t25, it is determined that vehicle 10 has stopped, so the reduction correction process ends and the retraction process begins. During the retraction process, the indicated braking force BPTr increases towards the required braking force BPRq, and the braking device 30 operates based on this indicated braking force BPTr. Then, if at time t26, the indicated braking force BPTr becomes the required braking force BPRq, the braking control at stop ends.

[0072] Here, a comparative example is explained where braking control is not performed when stopping. For example... Figure 5As shown by the dashed line in (D), in the comparative example, the required braking force BPRq is continuously set as the indicated braking force BPTRA. Therefore, as Figure 5 As shown by the dashed line in (C), at the moment the vehicle 10 stops, the absolute value of the front-to-rear acceleration Gx decreases sharply. In this case, the pitch attitude of the vehicle 10 changes drastically due to the sharp change in the absolute value of the front-to-rear acceleration Gx. Furthermore, before the vehicle 10 stops, the inertial force caused by the deceleration of the vehicle 10 acts on the passengers of the vehicle 10. The greater the absolute value of the front-to-rear acceleration Gx, the greater the inertial force at this time. Therefore, if the vehicle 10 stops, this inertial force becomes 0 (zero). In other words, if the absolute value of the front-to-rear acceleration Gx decreases sharply due to the stopping of the vehicle 10, the inertial force acting on the passengers also decreases sharply. If the pitch attitude and inertial force change drastically due to stopping, there is a concern that passengers may experience discomfort.

[0073] In this embodiment, as Figure 6 As shown in (C), compared to the comparative example, the vehicle 10 can be brought to a stop while reducing the absolute value of the forward and backward acceleration Gx. This suppresses the abrupt change in the pitch attitude of the vehicle 10 caused by stopping. Furthermore, it also suppresses the abrupt decrease in the aforementioned inertial force caused by stopping.

[0074] Therefore, in this embodiment, even when the vehicle 10 traveling at low speed requires braking, it is possible to suppress abrupt changes in the pitch posture of the vehicle 10 that is stopped.

[0075] In this embodiment, the following effects can be further obtained.

[0076] (1) The smaller the vehicle speed VS at the moment the braking requirement is generated, the smaller the value is set as the first vehicle speed determination value VSth1 by the processing circuit 51. Therefore, even if the vehicle speed VS at the moment the braking requirement is generated is small, the processing circuit 51 can still perform braking control at the time of stopping. Thus, the braking control device 50 can stop the vehicle 10 with the braking force BPA1 being smaller than the required braking force BPRq, regardless of the magnitude of the vehicle speed VS at the moment the braking requirement is generated.

[0077] (2) The processing circuit 51 sets a first vehicle speed determination value VSth1 based on the deceleration DVS of the vehicle 10. Therefore, even if the driver operates the braking operation component 11 at a high speed, the processing circuit 51 can still perform braking control when stopping. Thus, regardless of the deceleration DVS of the vehicle during braking, the braking control device 50 can stop the vehicle 10 while making the braking force BPA1 smaller than the required braking force BPRq.

[0078] <Example of Change>

[0079] The above embodiments can be modified as follows. The above embodiments and the following modifications can be combined with each other within the scope of technical inconsistency.

[0080] • When braking at a stop, if it includes reduction correction processing and retraction processing, it may not include increase correction processing. Figure 6 The diagram shows an example of a timing diagram for a stop braking control that does not include an increase correction process.

[0081] like Figure 6 As shown in (A), vehicle 10 is traveling at a speed VS that is less than the first vehicle speed VS1. At time t31, when vehicle 10 is traveling at such a low speed, the driver begins to operate the braking control component 11. Thus, as... ​ As shown in (B), the required braking force BPRq is derived and set as the indicated braking force BPTr. Then, the braking device 30 operates based on the indicated braking force BPTr.

[0082] If braking is required in this manner, the vehicle speed determination value VSth11 is set such that the smaller the vehicle speed VS at that time, the smaller the vehicle speed determination value VSth11. The vehicle speed determination value VSth11 is equivalent to the second vehicle speed determination value VSth2 in the above embodiment. In this modified example, the vehicle speed determination value VSth11 corresponds to a "threshold". In this modified example, the vehicle speed determination value VSth11 is set to be smaller than the vehicle speed VS at time t31.

[0083] At time t32, the vehicle speed VS becomes the vehicle speed determination value VSth11, so the braking control reduction correction process begins when stopping. In the reduction correction process, the indicated braking force BPTr is reduced to the parking holding braking force BPth, and the braking device 30 operates based on this indicated braking force BPTr. The parking holding braking force BPth is smaller than the required braking force BPRq. Therefore, the braking force BPA1 is smaller than the required braking force BPRq.

[0084] At time t33, the indicated braking force BPTr becomes the parking holding braking force BPth, so the indicated braking force BPTr remains the parking holding braking force BPth.

[0085] At time t34, it is determined that vehicle 10 has stopped, so the reduction correction process ends and the retraction process begins. During the retraction process, the indicated braking force BPTr increases towards the required braking force BPRq, and the braking device 30 operates based on this indicated braking force BPTr. Then, if at time t35, the indicated braking force BPTr becomes the required braking force BPRq, the braking control during stopping ends.

[0086] In this modified example, even if a braking requirement arises while the vehicle 10 is traveling at a low speed, the processing circuit 51 can still perform stop braking control. Therefore, in this modified example, even if a braking requirement arises while the vehicle 10 is traveling at a low speed, it is possible to suppress abrupt changes in the pitch attitude of the vehicle 10 that accompanies it to a stop.

[0087] • The threshold setting unit can set the threshold based on the vehicle speed VS, and can also disregard the deceleration DVS of the vehicle 10 when setting the threshold.

[0088] • As long as the value of a parameter decreases as the vehicle 10 approaches the stop position PS, the parking-related value acquisition unit can also acquire parameters other than the vehicle speed VS. For example, the parking-related value acquisition unit can also acquire the distance from the current position of the vehicle 10 to the stop position PS, i.e., the stopping distance, as the parking-related value. In this case, the threshold setting unit sets the determination value related to the stopping distance, i.e., the stopping distance determination value, as the threshold. Specifically, the shorter the stopping distance at the moment the braking request is generated, the smaller the value set by the threshold setting unit as the stopping distance determination value. Thus, the braking control device can achieve the same operation and effect as in the above embodiment.

[0089] Alternatively, for example, the parking-related value acquisition unit can acquire the time required until the vehicle 10 comes to a stop, i.e., the stop prediction time, as the parking-related value. In this case, the threshold setting unit sets the determination value related to the stop prediction time, i.e., the stop prediction time determination value, as the threshold. Specifically, the shorter the stop prediction time at the moment the braking request is generated, the smaller the value set by the threshold setting unit as the stop prediction time determination value. Thus, the braking control device can achieve the same operation and effect as the above-described embodiment. Furthermore, an example of stop prediction time is TTC. TTC is an abbreviation for "Time To Collision".

[0090] In addition, the aforementioned stopping distance and stopping prediction time can also be described as parameters whose values ​​gradually decrease over time when the vehicle decelerates due to the application of braking force.

[0091] Furthermore, the parking-related value acquisition unit may also acquire at least one of vehicle speed VS, stopping distance, and stopping prediction time as parking-related values. For example, the parking-related value acquisition unit may also acquire vehicle speed VS and stopping distance as parking-related values. In this case, it is preferable that the control unit starts braking control when stopping is conditional on at least one of vehicle speed VS being below a threshold and stopping distance being below a threshold.

[0092] • The stop position setting unit can also set the stop position PS using a method different from that using vehicle speed VS or deceleration DVS. For example, if the distance from the current vehicle to the vehicle in front can be obtained, the stop position setting unit can set the stop position PS based on that distance. In this case, the shorter the distance, the closer the stop position setting unit will be to the current vehicle's position as the stop position PS.

[0093] • The braking control device can also control not only the friction braking force but also the regenerative braking force when braking control is executed at a stop. In this case, the sum of the friction braking forces applied to the vehicle 10 and the sum of the regenerative braking forces applied to the vehicle 10 constitutes the braking force BPA1.

[0094] • In the above embodiment, when the vehicle brakes in conjunction with the driver's operation of the brake operating component 11, the processing circuit 51 performs stop-time braking control. However, the processing circuit 51 may also perform stop-time braking control during automatic braking.

[0095] • The processing circuit 51 can be configured as one or more dedicated hardware circuits, or a combination thereof, such as a processor that operates according to a computer program, dedicated hardware that performs at least a portion of various processes, or other dedicated hardware that performs such processes. Examples of dedicated hardware include application-specific integrated circuits (ASICs). The processor includes a CPU and memories such as RAM and ROM, which store program code or commands configured to cause the CPU to perform processing. Memory, or storage medium, includes all usable media accessible to general-purpose or special-purpose computers.

[0096] Other Technological Ideas

[0097] Next, the technical ideas that can be grasped based on the above-described implementation methods and variations will be described.

[0098] [Note 1] Preferably, the above-mentioned braking control upon stopping includes:

[0099] The correction process increases the braking force applied to the vehicle compared to the aforementioned braking force requirement; and

[0100] The reduction correction process is performed after the increase correction process has been completed, so that the braking force applied to the vehicle is reduced compared to the required braking force value.

[0101] [Appendix 2] A braking control device includes: a parking-related value acquisition unit, which acquires a parking-related value that gradually decreases over time when the vehicle decelerates due to the application of braking force;

[0102] The control unit initiates stop-time braking control when the aforementioned parking-related value falls below a threshold value. This stop-time braking control is a braking control that stops the vehicle while applying a braking force that is less than the required braking force.

[0103] The threshold setting unit sets the threshold to a smaller value if the parking-related value is smaller before the braking control at the stop begins.

[0104] Furthermore, the expression "at least one" as used in this specification refers to "more than one" of the desired options. As an example, if the number of options is two, the expression "at least one" as used in this specification means "only one option" or "both of the two options". As another example, if the number of options is three or more, the expression "at least one" as used in this specification means "only one option" or "a combination of any two or more options".

Claims

1. A braking control device, wherein, have: The parking-related value acquisition unit acquires parking-related values ​​that decrease as the vehicle approaches the designated stopping position. The control unit initiates stop-time braking control when the aforementioned parking-related value falls below a predetermined threshold. This stop-time braking control is a braking control that stops the vehicle while applying a braking force that is less than the required braking force. The threshold setting unit sets the threshold to a smaller value if the parking-related value is smaller before the braking control at the stop begins.

2. The braking control device according to claim 1, wherein, The smaller the parking-related value at the moment when braking requirements for the aforementioned vehicle are generated, the smaller the threshold setting unit will set the threshold to.

3. The braking control device according to claim 1 or claim 2, wherein, The threshold setting unit sets the threshold based on the deceleration of the vehicle.

4. The braking control device according to claim 1, wherein, The parking-related value acquisition unit acquires at least one of the vehicle's speed and the distance from the vehicle's current position to the stopping position, i.e., the stopping distance, as the parking-related value.

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