Vehicle control device, vehicle control method, and vehicle control system

Abstract

To provide a vehicle control device, a vehicle control method, and a vehicle control system which can suppress grounding loads of front wheels from rapidly decreasing in a turning state of a vehicle.SOLUTION: A vehicle control device, a vehicle control method, and a vehicle control system according to the present invention, when obtaining a signal concerning releasing-operation by a brake operation part, in one aspect, decrease braking force generated in a braking device, at a first decreasing gradient, when a physical amount concerning a steering angle of a vehicle is smaller than a predetermined steering angle threshold, and output a braking command for decreasing the braking force generated in the braking device, at a second decreasing gradient that is smaller than the first decreasing gradient, when the physical amount concerning the steering angle of the vehicle is equal to the predetermined steering angle threshold or is larger than the steering angle threshold.SELECTED DRAWING: Figure 3

Description

Technical Field

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[0001] The present invention relates to a vehicle control device, a vehicle control method, and a vehicle control system.

Background Art

[0002] The vehicle braking device of Patent Document 1 includes wheel rotation suppression means for suppressing the rotation of each of four wheels, braking force distribution determination means for distributing the braking force required for the entire vehicle to each of the four wheels in a ratio corresponding to the ground load of each of those wheels, and control means for controlling each of the wheel rotation suppression means based on at least the braking force ratio determined by the braking force distribution determination means.

Prior Art Document

Patent Document

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, when a vehicle travels on a winding road, the driver may need to quickly switch from the brake pedal to the accelerator pedal. However, when the switching operation from the brake pedal to the accelerator pedal is quickly performed in a turning state of the vehicle, there is a problem that the ground load of the front wheels of the vehicle rapidly decreases, resulting in a large change in the vehicle posture.

[0005] The present invention has been made in view of the conventional situation, and an object thereof is to provide a vehicle control device, a vehicle control method, and a vehicle control system that can suppress a rapid decrease in the ground load of the front wheels in a turning state of the vehicle.

Means for Solving the Problems

[0006] According to the vehicle control device, vehicle control method, and vehicle control system of the present invention, in one embodiment, when a signal relating to the release operation of the brake operation unit is acquired, if the physical quantity relating to the steering angle of the vehicle is smaller than a predetermined steering angle threshold, the braking force generated by the braking device is reduced by a first decreasing gradient, and if the physical quantity relating to the steering angle of the vehicle becomes equal to or greater than the steering angle threshold, a braking command is output to reduce the braking force generated by the braking device by a second decreasing gradient smaller than the first decreasing gradient. [Effects of the Invention]

[0007] According to the present invention, it is possible to suppress the sudden decrease in the ground contact load of the front wheels when the vehicle is turning. [Brief explanation of the drawing]

[0008] [Figure 1] This is the vehicle control systems chapter. [Figure 2] This is a functional block diagram illustrating the process of controlling decreasing gradients. [Figure 3] This diagram shows the difference in the decrease gradient of brake fluid pressure (braking force) when the decrease gradient control is turned on or off. [Figure 4] This is a diagram showing the correlation between the steering angle θ and the first ratio R1. [Figure 5] This is a diagram showing the correlation between vehicle speed VS and the second ratio R2. [Figure 6] This is a diagram showing the correlation between the accelerator opening angle AO and the third ratio R3. [Figure 7] This diagram shows the difference in front wheel ground contact load when the decreasing gradient control is turned on or off. [Modes for carrying out the invention]

[0009] Hereinafter, embodiments of the vehicle control device, vehicle control method, and vehicle control system according to the present invention will be described with reference to the drawings. Figure 1 shows one embodiment of a vehicle control system 110 installed in a vehicle 100. Vehicle 100 is a four-wheeled automobile having a pair of front wheels 101, 102 and a pair of rear wheels 103, 104. The vehicle control system 110 includes a braking device 200 and a vehicle control device 300.

[0010] The braking device 200 generates braking force on the wheels 101-104 by the driver operating the brake control unit. The braking system 200 includes a brake pedal 210 as a brake operating unit, brake actuators 221-224 located on each wheel 101-104, a brake control device 230, a brake fluid pressure sensor 240, and a brake switch 250.

[0011] The brake actuators 221 and 224 are hydraulic brake actuators that generate braking force using hydraulic pressure supplied from, for example, a hydraulic pressure generator (not shown). The brake control device 230 is an electronic control device equipped with a microcomputer, which controls the hydraulic pressure supplied from the hydraulic pressure generator to the brake actuators 221-224. Furthermore, the brake actuators 221-224 are not limited to hydraulic types; for example, they may be electric calipers that generate frictional force through the drive of a motor.

[0012] The brake fluid pressure sensor 240 detects the brake fluid pressure BP [Pa] (in other words, the pressing force or braking force of the brake pads) supplied to the brake actuators 221-224. The brake switch 250 is a sensor that detects the operation of the brake pedal 210. It turns on when the driver depresses the brake pedal 210, in other words, when the driver performs a braking operation that generates braking force, and turns off when the driver releases the brake pedal 210, in other words, when the driver releases the braking operation of the brake pedal 210.

[0013] Incidentally, the vehicle control system 110 can determine whether or not the driver has performed a braking operation on the brake pedal 210 from the output of a brake pedal sensor that detects the stroke amount (in other words, the depression amount) of the brake pedal 210. Specifically, the vehicle control system 110 sets a brake on / off flag, which is a flag indicating whether or not the brake pedal 210 is being braked, by comparing the output of the brake pedal sensor with a threshold value, and based on the brake on / off flag, it can determine whether or not the driver has performed a braking operation.

[0014] The vehicle control device 300 is an electronic control device including a microcomputer 310. The microcomputer 310 includes an MPU (Microprocessor Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like. Then, as will be described later, when the driver releases the brake pedal 210 (in other words, performs a braking release operation), the microcomputer 310 functions as a control unit that outputs a control command for controlling the decreasing gradient of the braking force.

[0015] The vehicle 100 also includes a steering angle sensor 410 that detects the steering angle θ [deg] of the front wheels [101, 102] from the rotation angle of a steering wheel 400 (in other words, a steering operation member) that constitutes a steering device provided in the vehicle 100, a vehicle speed sensor 500 that detects the traveling speed of the vehicle 100 (hereinafter referred to as the vehicle speed VS [km / h]), and an accelerator opening sensor 610 that detects an accelerator opening AO [%] corresponding to the depression amount of an accelerator pedal 600 as an accelerator operation unit operated by the driver. Incidentally, the steering angle sensor 410 can be a sensor that detects the steering angle of the front wheels [101, 102] as the steering angle.

[0016] The microcomputer 310 acquires a brake hydraulic pressure signal BP output from the brake hydraulic pressure sensor 240, an on / off signal of the brake switch 250, a signal of a steering angle θ (in other words, a physical quantity related to the steering angle θ) output from the steering angle sensor 410, a vehicle speed VS signal output from the vehicle speed sensor 500, and an accelerator opening AO signal output from the accelerator opening sensor 610. When the microcomputer 310 detects a stepping-back operation of the brake pedal 210 from the on / off signal of the brake switch 250 (in other words, when acquiring a signal related to the release operation of the brake operation unit), the microcomputer 310 performs a decreasing gradient control to make the decreasing gradient of the braking force generated by the braking device 200 smaller than the standard, with at least the condition that the steering angle θ is greater than or equal to a predetermined steering angle threshold.

[0017] FIG. 2 is a functional block diagram showing the process of the decreasing gradient control by the microcomputer 310. The microcomputer 310 has functional units such as a driver operation detection unit 311, a brake pressure attenuation unit 312, a ratio setting unit 313, and an intervention control unit 314, and executes the decreasing gradient control (in other words, the vehicle control method according to the present invention) through these units.

[0018] The driver operation detection unit 311 acquires the brake hydraulic pressure signal BP from the brake hydraulic pressure sensor 240 and acquires the on / off signal of the brake switch 250. Then, the driver operation detection unit 311 detects the timing when the driver steps back the brake pedal 210 to release the braking operation as the timing when the brake switch 250 switches from on to off.

[0019] When the vehicle 100 includes a brake sensor that detects the depression amount of the brake pedal 210 (in other words, the operation amount of the brake pedal 210), the driver operation detection unit 311 can detect the braking operation and release operation of the brake pedal 210 by the driver by comparing the depression amount of the brake pedal 210 with a threshold value. When the driver operation detection unit 311 detects the timing when the driver releases the brake pedal 210, it samples the brake fluid pressure signal BP output by the brake fluid pressure sensor 240 at that time to determine the brake fluid pressure BPC (in other words, the braking force) at the time the driver releases the brake pedal 210.

[0020] The brake pressure damping unit 312 acquires the brake fluid pressure signal BPC at the timing detected by the driver operation detection unit 311 when the driver releases the brake pedal 210. The brake pressure damping unit 312 then sets a brake fluid pressure indicator value BP2, which decreases over time at a predetermined second decreasing gradient, using the brake fluid pressure signal BPC at the time the driver releases the brake pedal 210 as the initial value.

[0021] Here, the second reduction gradient in the brake pressure damping section 312 is adapted to be smaller than the first reduction gradient (in other words, the standard reduction gradient), which is the reduction gradient of the brake fluid pressure BP when the microcomputer 310 does not perform reduction gradient control (first reduction gradient > second reduction gradient). In other words, the brake pressure damping unit 312 sets the brake fluid pressure indicator value BP2 so that the decrease in braking force from the moment the driver releases the brake pedal 210 is more gradual than when the decrease gradient control is not implemented.

[0022] Figure 3 is a time chart comparing the change in brake fluid pressure BP when the microcomputer 310 does not perform decreasing gradient control with the change in the brake fluid pressure instruction value BP2 set by the brake pressure damping unit 312. If the microcomputer 310 does not perform gradient reduction control, when the driver releases the brake pedal 210, the brake fluid pressure BP decreases sharply at a predetermined first gradient reduction. In other words, if the microcomputer 310 does not perform gradient reduction control, it will provide the brake control device 230 with a brake fluid pressure instruction value BP1 that decreases at the first gradient reduction.

[0023] In contrast, the brake fluid pressure indicator value BP2 set by the brake pressure damping unit 312 is set to decrease at a slower rate than when no gradient control is performed, resulting in a more gradual decrease. Thus, the decreasing gradient control of the microcomputer 310 is a control that slows down the decrease in brake fluid pressure BP that occurs when the driver releases the brake pedal 210.

[0024] The ratio setting unit 313 acquires a signal of the steering angle θ of the steering wheel 400 from the steering angle sensor 410, a signal of the vehicle speed VS from the vehicle speed sensor 500, and a signal of the accelerator opening AO from the accelerator opening sensor 610. Then, the ratio setting unit 313 sets a ratio for controlling the intervention of the decreasing gradient control based on the acquired signals, specifically the application ratio of the brake fluid pressure instruction value BP2 set by the brake pressure damping unit 312.

[0025] The ratio setting unit 313 sets the first ratio R1 based on the steering angle θ signal, the second ratio R2 based on the vehicle speed VS signal, and the third ratio R3 based on the accelerator opening AO signal. The first ratio R1, the second ratio R2, and the third ratio R3 are set to values ​​greater than or equal to the minimum value of 0 and less than or equal to the maximum value of 1.0.

[0026] Here, R1, R2, R3=0 is a command that does not involve the decreasing gradient control, that is, a command to reduce the brake fluid pressure BP by the first decreasing gradient in response to the release operation of the brake pedal 210, in other words, a command to select the brake fluid pressure instruction value BP1. On the other hand, R1, R2, R3 = 1.0 is a command to intervene in the decreasing gradient control, that is, a command to reduce the brake fluid pressure BP by a second decreasing gradient smaller than the first decreasing gradient in response to the release operation of the brake pedal 210, in other words, a command to select the brake fluid pressure value BP2.

[0027] Figure 4 is a diagram illustrating the correlation between the absolute value of the steering angle θ [deg] and the first ratio R1. The first ratio R1 is set to zero when the absolute value of the steering angle θ is less than the first steering angle threshold θTH1 (θTH1 > 0). When the absolute value of the steering angle θ is greater than or equal to the first steering angle threshold θTH1 and less than the second steering angle threshold θTH2 (0 < θTH1 < θTH2), the ratio R1 increases in proportion to the increase in the absolute value of the steering angle θ. It reaches its maximum value of 1.0 when the absolute value of the steering angle θ becomes equal to the second steering angle threshold θTH2, and maintains a value of 1.0 when the absolute value of the steering angle θ is greater than or equal to the second steering angle threshold θTH2. For example, the first steering angle threshold θTH1 is approximately 10 degrees, and the second steering angle threshold θTH2 is approximately 20 degrees.

[0028] The first ratio R1, based on the steering angle θ, is a ratio for initiating the decrease gradient control of the microcomputer 310 when the vehicle 100 is turning, and the first steering angle threshold θTH1 is a threshold for distinguishing whether or not the vehicle 100 is turning. Furthermore, when the absolute value of the steering angle θ is smaller than the first steering angle threshold θTH1 and it is determined that the vehicle 100 is not in a turning state, the ratio setting unit 313 sets the first ratio R1 to zero to prevent the reduction gradient control from intervening. In other words, the first ratio R1 is set so that when the steering angle θ is smaller than a predetermined steering angle threshold, the braking force generated by the braking device 200 is reduced by a first decreasing gradient.

[0029] Furthermore, when the absolute value of the steering angle θ becomes greater than or equal to the first steering angle threshold θTH1, the ratio setting unit 313 increases the first ratio R1 as the absolute value of the steering angle θ increases, thereby transitioning from a state of non-intervention of the decreasing gradient control to a state of intervention of the decreasing gradient control. In other words, the first ratio R1 is set so that when the steering angle θ reaches a predetermined steering angle threshold or becomes greater than the steering angle threshold, the braking force generated by the braking device 200 is reduced by a second reduction gradient that is smaller than the first reduction gradient.

[0030] Figure 5 is a diagram illustrating the correlation between vehicle speed VS [km / h] and the second ratio R2. The second ratio R2 is set to zero when the vehicle speed VS is lower than the first vehicle speed threshold VSTH1 (VSTH1 > 0), increases proportionally to the increase in the vehicle speed VS when the vehicle speed VS is equal to or higher than the first vehicle speed threshold VSTH1 and lower than the second vehicle speed threshold VSTH2 (0 < VSTH1 < VSTH2), reaches the maximum value of 1.0 when the vehicle speed VS reaches the second vehicle speed threshold VSTH2, and maintains 1.0 when the vehicle speed VS is equal to or higher than the second vehicle speed threshold VSTH2. For example, the first vehicle speed threshold VSTH1 (the first speed threshold) is a value of about 20 km / h, and the second vehicle speed threshold VSTH2 (the second speed threshold) is a value of about 30 km / h.

[0031] The second ratio R2 based on the vehicle speed VS is a ratio for intervening in the deceleration control of the microcomputer 310 in the running state of the vehicle 100. The first vehicle speed threshold VSTH1 is a threshold for distinguishing whether the vehicle 100 is in a normal running state, a stopped state or a very low speed running state. Then, when it is determined that the vehicle speed VS is lower than the first vehicle speed threshold VSTH1 and the running state of the vehicle 100 is not a state where the intervention of the deceleration control becomes effective, the ratio setting unit 313 sets the second ratio R2 to zero so as not to intervene in the deceleration control. That is, when the vehicle speed VS is smaller than a predetermined vehicle speed threshold, the second ratio R2 is set to decrease the braking force generated by the braking device 200 at the first deceleration gradient.

[0032] Furthermore, when the vehicle speed VS becomes equal to or higher than the first vehicle speed threshold VSTH1, the ratio setting unit 313 increases the second ratio R2 as the vehicle speed VS increases, thereby transitioning from the non-intervention state of the deceleration control to the intervention state of the deceleration control. That is, when the vehicle speed VS reaches or becomes higher than a predetermined vehicle speed threshold, the second ratio R2 is set to decrease the braking force generated by the braking device 200 at a second deceleration gradient smaller than the first deceleration gradient.

[0033] FIG. 6 is a diagram illustrating the correlation between the accelerator opening AO [%] and the third ratio R3. The third ratio R3 is set to its maximum value of 1.0 when the accelerator opening AO is zero, decreases in proportion to the increase in accelerator opening AO from zero until it reaches the accelerator opening threshold AOTH (AOTH>0), reaches zero when accelerator opening AO reaches the accelerator opening threshold AOTH, and is held at zero when accelerator opening AO is greater than or equal to the accelerator opening threshold AOTH. For example, the accelerator opening threshold AOTH is around 5%.

[0034] The third ratio R3, based on the accelerator pedal opening AO, is a ratio that cancels the reduction gradient control and rapidly dampens the brake fluid pressure BP when the driver accelerates by pressing the accelerator pedal 600, and the accelerator pedal opening threshold AOTH is a threshold for distinguishing whether or not the driver accelerates by pressing the accelerator pedal 600. Then, when the accelerator opening AO is greater than the accelerator opening threshold AOTH and it is recognized that the driver has performed an acceleration operation (pressing the accelerator pedal 600), the ratio setting unit 313 sets the third ratio R3 to zero, thereby preventing the reduction gradient control from intervening.

[0035] Furthermore, the ratio setting unit 313 reduces the third ratio R3 as the accelerator opening AO increases from zero, thereby transitioning from a state of intervention in the decreasing gradient control to a state of non-intervention in the decreasing gradient control. In other words, the third ratio R3 is set so that when the braking force generated by the braking device 200 is being reduced by the second reduction gradient, and information regarding the driver's acceleration operation of the accelerator pedal is obtained, the braking force generated by the braking device 200 is reduced by the first reduction gradient.

[0036] The ratio setting unit 313 multiplies the first ratio R1, the second ratio R2, and the third ratio R3 set as described above to obtain the final ratio R (R = R1 × R2 × R3), and outputs a signal of ratio R, that is, a signal indicating whether or not to intervene in decreasing gradient control, to the intervention control unit 314. Here, the final ratio R is zero when at least one of the first ratio R1, the second ratio R2, and the third ratio R3 is zero; in other words, it is a non-intervention instruction for decreasing gradient control.

[0037] Furthermore, when the first ratio R1, the second ratio R2, and the third ratio R3 are all 1, the value becomes 1, or in other words, it becomes an intervention instruction for decreasing gradient control. Furthermore, the final ratio R is greater than 0 and less than 1.0, i.e., a transition instruction between no intervention and intervention of decreasing gradient control, when all three ratios R1, R2, and R3 are greater than zero, and at least one of them is less than 1.0.

[0038] The intervention control unit 314 is a functional unit that switches between intervention and non-intervention of the decreasing gradient control by changing the brake fluid pressure instruction value BPTG, which is a braking command for all four wheels output to the brake control device 230, according to the ratio R signal obtained from the ratio setting unit 313. The brake control device 230 then controls the brake fluid pressure BP after the brake pedal 210 has been released, according to the brake fluid pressure instruction value BPTG obtained from the intervention control unit 314.

[0039] Here, when the ratio R signal obtained from the ratio setting unit 313 is 1, the intervention control unit 314 outputs the brake fluid pressure instruction value BP2, which decreases by the second decreasing gradient and is determined by the brake pressure damping unit 312, directly to the brake control device 230 as the brake fluid pressure instruction value BPTG. In other words, when the ratio R signal obtained from the ratio setting unit 313 is 1, the intervention control unit 314 instructs the brake control device 230 to intervene in the decreasing gradient control.

[0040] On the other hand, when the signal of ratio R obtained from the ratio setting unit 313 is zero, the intervention control unit 314 stops outputting the brake fluid pressure instruction value BP2 determined by the brake pressure damping unit 312 to the brake control device 230, and outputs an instruction to reduce the brake fluid pressure by the first reduction gradient (standard reduction gradient), in other words, the brake fluid pressure instruction value BP1 that decreases by the first reduction gradient, as the brake fluid pressure instruction value BPTG to the brake control device 230. In other words, when the ratio R signal obtained from the ratio setting unit 313 is zero, the intervention control unit 314 instructs the brake control device 230 to refrain from intervening in the decreasing gradient control.

[0041] Furthermore, when the ratio R signal obtained from the ratio setting unit 313 is greater than zero and less than 1.0, the intervention control unit 314 changes the brake fluid pressure indicator value BPTG between the indicator value BP2 which decreases with the second decreasing gradient and the indicator value BP1 which decreases with the first decreasing gradient, according to the ratio R signal. In other words, the intervention control unit 314 adjusts the instruction value BPTG output to the brake control device 230 to be closer to the instruction value BP1 that decreases with the first decreasing gradient (standard decreasing gradient) the closer the ratio R signal is to zero, and adjusts the instruction value BPTG output to the brake control device 230 to be closer to the instruction value BP2 that decreases with the second decreasing gradient the closer the ratio R signal is to 1.0.

[0042] For example, when the driver presses down on the accelerator pedal 600, the brake fluid pressure indicator BPTG output to the brake control device 230 gradually changes from an indicator BP2 that decreases at a second decreasing gradient to an indicator BP1 that decreases at a first decreasing gradient, in accordance with the increase in the amount the accelerator pedal 600 is pressed down.

[0043] Then, when the accelerator opening AO increases to the accelerator opening threshold AOTH, the third ratio R3 becomes zero and the final ratio R also becomes zero, so the brake fluid pressure instruction value BPTG output to the brake control device 230 becomes the instruction value BP1 which decreases with the first decreasing gradient, and the intervention of the decreasing gradient control is released. In other words, when the vehicle 100 is turning and the driver is not accelerating using the accelerator pedal 600, if the brake pedal 210 is released (released), a reduction gradient control is activated to slow the decrease in brake fluid pressure BP. If acceleration using the accelerator pedal 600 is performed while the reduction gradient control is active, the system transitions to a state where the reduction gradient control is not active.

[0044] As described above, the microcomputer 310 of the vehicle control device 300 performs a reduction gradient control that actively slows down the decrease gradient of the brake fluid pressure BP when the driver releases the brake pedal 210 while the vehicle 100 is turning. This reduction gradient control suppresses a sudden decrease in brake fluid pressure BP, i.e., braking force, which in turn suppresses a sudden decrease in the ground contact load of the front wheels 101 and 102. As a result, changes in vehicle posture associated with releasing the brake pedal 210 can be suppressed.

[0045] Therefore, when the vehicle 100 is driving on a winding road or the like, even if the driver quickly switches from the brake pedal 210 to the accelerator pedal 600, the vehicle's posture is prevented from becoming unstable, and the stability of the vehicle 100 during cornering is improved. Furthermore, when the accelerator pedal 600 is pressed (in other words, when an acceleration operation is performed) while the deceleration gradient control is in operation, the vehicle control device 300 quickly reduces the brake fluid pressure BP at the first deceleration gradient, thereby preventing the acceleration response to the driver's acceleration operation from becoming sluggish due to a delay in the reduction of braking force.

[0046] Figure 7 is a time chart showing the difference in brake fluid pressure BP (braking force) and the difference in ground contact load of the front wheels 101 and 102, depending on whether or not the decreasing gradient control intervenes when the driver releases the brake operation of the brake pedal 210. At time t1, when the driver releases the brake pedal 210, the brake fluid pressure BP (braking force) will decrease. However, the decrease gradient control intervenes, making the decrease in brake fluid pressure more gradual.

[0047] Furthermore, the decrease in brake fluid pressure BP is made gradual by the decreasing gradient control, which suppresses the decrease in ground contact load on the front wheels 101 and 102. In other words, the change in vehicle posture associated with releasing the brake pedal 210 is suppressed, improving the stability of the vehicle 100 during cornering.

[0048] The technical concepts described in the above embodiments can be used in appropriate combinations, as long as no contradictions arise. Furthermore, although the contents of the present invention have been specifically described with reference to preferred embodiments, it will be obvious to those skilled in the art that various modifications can be taken based on the basic technical concept and teachings of the present invention.

[0049] In the above embodiment, the vehicle control device 300 applies the reduction gradient control to all four wheels. However, the vehicle control device 300 can select which wheels to apply the reduction gradient control to depending on the vehicle condition and driving conditions. For example, the wheels to which the reduction gradient control is applied can be limited to the wheels on the inside of the turn. Furthermore, in the above embodiment, the vehicle control device 300 gradually changes the ratio R in response to changes in steering angle θ, vehicle speed VS, and accelerator opening AO, but sets the ratio R to either 1 or zero depending on whether or not to intervene with decreasing gradient control, and changes the indicated value of the brake fluid pressure with a response delay in response to the stepwise switching of the ratio R.

[0050] Furthermore, the vehicle control device 300 can variably set the second decreasing gradient applied in the decreasing gradient control according to the deceleration when the brake pedal 210 is released, the brake fluid pressure (braking force), and other factors. Here, the vehicle control device 300 changes the second decreasing gradient to a smaller gradient the greater the deceleration or brake fluid pressure (braking force) when the brake pedal 210 is released.

[0051] Furthermore, the brake and accelerator operating sections are not limited to the brake pedal 210 and the accelerator pedal 600, and the vehicle 100 may also be equipped with manual operating sections that the driver operates manually as the brake and / or accelerator operating sections. Furthermore, the manual control unit can be a control unit that serves as both a brake control unit and an accelerator control unit, for example, a control grip that operates the accelerator when pulled towards the driver and the brake when pushed forward (in other words, pulling towards the driver is the acceleration operation and pushing forward is the braking operation).

[0052] Furthermore, the vehicle control device 300 can omit at least one of the settings for the second ratio R2 based on the vehicle speed VS and the third ratio R3 based on the accelerator opening angle AO. Furthermore, the vehicle control device 300 can, for example, perform deceleration gradient control when the driver has selected sport mode as the driving mode, and cancel the deceleration gradient control when sport mode is not selected. Furthermore, the vehicle control device 300 can also incorporate the functions of the brake control device 230. In other words, the brake control device 230 can be equipped with the decreasing gradient control function of the vehicle control device 300. [Explanation of Symbols]

[0053] 100…Vehicle, 101-104…Wheels, 200…Brake system, 210…Brake pedal (brake operating unit), 230…Brake control device, 300…Vehicle control device, 310…Microcomputer (control unit), 600…Accelerator pedal (accelerator operating unit)

Claims

1. A vehicle control device installed in a vehicle equipped with a braking system that generates braking force on the wheels by the driver operating a brake control unit, The control unit of the aforementioned vehicle control device is When a signal related to the release operation of the brake control unit is obtained, If the physical quantity relating to the steering angle of the vehicle is smaller than a predetermined steering angle threshold, the braking force generated by the braking device is reduced by a first decreasing gradient. If the physical quantity relating to the steering angle of the vehicle reaches or exceeds the steering angle threshold, a braking command is output to reduce the braking force generated by the braking device by a second reduction gradient smaller than the first reduction gradient. Vehicle control device.

2. A vehicle control device according to claim 1, The control unit is When the braking force generated by the braking device is being reduced by the second reduction gradient, if information regarding the driver's acceleration operation of the accelerator pedal is obtained, The braking command is output to reduce the braking force generated by the braking device by the first decreasing gradient. Vehicle control device.

3. A vehicle control device according to claim 1, The control unit is If the speed of the vehicle is less than a predetermined speed threshold, the braking command is output to reduce the braking force generated by the braking device by the first decreasing gradient, regardless of the magnitude of the physical quantity related to the steering angle of the vehicle. Vehicle control device.

4. A vehicle control method performed by a control unit installed in a vehicle equipped with a braking system that generates braking force on the wheels by the driver's operation of a brake control unit, The aforementioned control unit When a signal related to the release of the brake operation unit is obtained, If the physical quantity relating to the steering angle of the vehicle is smaller than a predetermined steering angle threshold, the braking force generated by the braking device is reduced by a first decreasing gradient. If the physical quantity relating to the steering angle of the vehicle reaches or exceeds the steering angle threshold, a braking command is output to reduce the braking force generated by the braking device by a second reduction gradient smaller than the first reduction gradient. Vehicle control method.

5. A braking system that generates braking force on the wheels through operation of the brake control unit by the driver, A control unit for controlling the braking device, When a signal related to the release of the brake operation unit is obtained, If the physical quantity relating to the steering angle of the vehicle is smaller than a predetermined steering angle threshold, the braking force generated by the braking device is reduced by a first decreasing gradient. If the physical quantity relating to the steering angle of the vehicle reaches or exceeds the steering angle threshold, a braking command is output to reduce the braking force generated by the braking device by a second reduction gradient smaller than the first reduction gradient. The control unit and, A vehicle control system equipped with the following features.

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