Control apparatus and control method

Abstract

To inhibit decrease of driver's comfort.SOLUTION: A control apparatus is a vehicle control apparatus including: a booster device 22 which increases a master cylinder pressure, a liquid pressure of a master cylinder 23, to increase a wheel cylinder pressure, a liquid pressure of a wheel cylinder 25, automatically and which is linked to a brake pedal 21; and a pump 46 which supplies a brake fluid from the master cylinder 23 to the wheel cylinder 25 to increase the wheel cylinder pressure automatically. The control apparatus further includes a control unit which performs a first pressure increasing control for increasing the wheel cylinder pressure automatically with the booster device 22 and a second pressure increasing control for increasing the wheel cylinder pressure automatically with the pump 46 in a switching manner. The control unit starts the first pressure increasing control when the wheel cylinder pressure is increased automatically and ends the first pressure increasing control and starts the second pressure increasing control when the wheel cylinder pressure exceeds a first threshold value.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a control device and a control method. [Background technology]

[0002] In recent years, technologies have been proposed that automatically control vehicle driving by taking over part or all of the driving operations performed by the driver. For example, as disclosed in Patent Document 1, a technology has been proposed that automatically drives a vehicle without relying on driving operations by the driver. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2017 / 208781 Summary of the Invention [Problem to be solved by the invention]

[0004] Examples of technologies for automatically controlling vehicle driving include automatic parking control, which automatically parks a vehicle, and adaptive cruise control, which maintains a constant distance between a vehicle and a preceding vehicle. These technologies automatically apply braking force to a vehicle by, for example, pressure-increasing control, which automatically increases wheel cylinder pressure, which is hydraulic pressure in the wheel cylinders. When pressure-increasing control is performed, noise may be generated, which may reduce driver comfort. Therefore, it is desirable to suppress the reduction in driver comfort.

[0005] In view of the above, an object of the present invention is to provide a control device and a control method that can suppress a decrease in driver comfort. [Means for solving the problem]

[0006] In order to solve the above problem, the control device is a vehicle control device that automatically increases the wheel cylinder pressure, which is the hydraulic pressure in the wheel cylinder, by increasing the master cylinder pressure, which is the hydraulic pressure in the master cylinder, and is equipped with a pressure increase device that is linked to the brake pedal, and a pump that automatically increases the wheel cylinder pressure by supplying brake fluid from the master cylinder to the wheel cylinder, and is equipped with a control unit that switches between first pressure increase control that automatically increases the wheel cylinder pressure using the pressure increase device, and second pressure increase control that automatically increases the wheel cylinder pressure using the pump, and the control unit starts the first pressure increase control when automatically increasing the wheel cylinder pressure, and ends the first pressure increase control and starts the second pressure increase control when the wheel cylinder pressure exceeds a first threshold value.

[0007] In order to solve the above problem, the control method is a control method for a vehicle equipped with a pressure booster device that automatically increases the wheel cylinder pressure, which is the hydraulic pressure in the wheel cylinder, by increasing the master cylinder pressure, which is the hydraulic pressure in the master cylinder, and that is linked to the brake pedal, and a pump that automatically increases the wheel cylinder pressure by supplying brake fluid from the master cylinder to the wheel cylinder, in which a control unit of the control device switches between and executes a first pressure boost control that automatically increases the wheel cylinder pressure using the pressure booster device, and a second pressure boost control that automatically increases the wheel cylinder pressure using the pump, and the control unit starts the first pressure boost control when automatically increasing the wheel cylinder pressure, and ends the first pressure boost control and starts the second pressure boost control when the wheel cylinder pressure exceeds a first threshold value. [Effects of the Invention]

[0008] According to the present invention, it is possible to suppress a decrease in driver comfort. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic diagram showing a general configuration of a vehicle according to an embodiment of the present invention; [Figure 2] 1 is a schematic diagram showing a general configuration of a brake system for a vehicle according to an embodiment of the present invention; [Figure 3] FIG. 2 is a block diagram showing an example of a functional configuration of a control device according to an embodiment of the present invention. [Figure 4] 4 is a flowchart illustrating an example of a flow of processing performed by a control device according to an embodiment of the present invention. [Figure 5] FIG. 4 is a diagram illustrating an example of a movable range of a brake pedal according to the embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Dimensions, materials, and other specific values ​​shown in the embodiments are merely examples for facilitating understanding of the invention and, unless otherwise specified, do not limit the present invention. In this specification and drawings, elements having substantially the same functions and configurations are designated by the same reference numerals to avoid redundant explanation, and elements not directly related to the present invention are not shown.

[0011] <Vehicle configuration> The configuration of a vehicle 10 according to an embodiment of the present invention will be described with reference to FIGS.

[0012] Fig. 1 is a schematic diagram showing the general configuration of a vehicle 10. As shown in Fig. 1, the vehicle 10 includes a steering mechanism 11, a drive source 12, a hydraulic control unit 13, a plurality of ambient environment sensors 14, a plurality of wheel speed sensors 15, and a control device 16.

[0013] The steering mechanism 11 is a mechanism that changes the steering angle of the vehicle 10. The steering angle of the vehicle 10 means the turning angle of the tires of the vehicle 10. The steering mechanism 11 includes a steering wheel 11a. The driver of the vehicle 10 can change the steering angle by performing a steering operation using the steering wheel 11a.

[0014] The drive source 12 outputs a drive force that is transmitted to the drive wheels of the vehicle 10. Examples of the drive source 12 include an engine and an electric motor.

[0015] The hydraulic pressure control unit 13 controls the braking force of the vehicle 10. The hydraulic pressure control unit 13 controls the braking force applied to the wheels by controlling the wheel cylinder pressure, which is the hydraulic pressure of the brake fluid in the wheel cylinder. Details of the hydraulic pressure control unit 13 will be described later.

[0016] The ambient environment sensors 14 detect ambient environment information relating to the environment around the vehicle 10. In the example of FIG. 1 , four ambient environment sensors 14 are provided at the left front, right front, left rear, and right rear of the vehicle 10, respectively. The left front ambient environment sensor 14 detects ambient environment information on the left front of the vehicle 10. The right front ambient environment sensor 14 detects ambient environment information on the right front of the vehicle 10. The left rear ambient environment sensor 14 detects ambient environment information on the left rear of the vehicle 10. The right rear ambient environment sensor 14 detects ambient environment information on the right rear of the vehicle 10.

[0017] The ambient environment information detected by the ambient environment sensor 14 may be information related to the distance or direction to an object located around the vehicle 10 (e.g., relative position, relative distance, relative speed, relative acceleration, etc.), or may be characteristics of the object located around the vehicle 10 (e.g., type of object, shape of the object itself, markings on the object, etc.). The ambient environment sensor 14 may be, for example, a radar, a lidar sensor, an ultrasonic sensor, etc.

[0018] The wheel speed sensor 15 is provided on each wheel and detects the wheel speed of each wheel.

[0019] The control device 16 controls the operation of the vehicle 10. The control device 16 is built into the hydraulic control unit 13. However, the control device 16 may be provided outside the hydraulic control unit 13.

[0020] The control device 16 includes a CPU (Central Processing Unit) which is an arithmetic processing device, a ROM (Read Only Memory) which is a storage element for storing programs used by the CPU, calculation parameters, etc., and a RAM (Random Access Memory) which is a storage element for temporarily storing parameters, etc. that change as appropriate during execution of the CPU. Details of the control device 16 will be described later.

[0021] Fig. 2 is a schematic diagram showing the general configuration of a brake system 20 of a vehicle 10. The brake system 20 is mounted on the vehicle 10 and controls the braking force generated in the vehicle 10. As shown in Fig. 2, the brake system 20 includes a hydraulic control unit 13, a brake pedal 21, an electric booster 22, a master cylinder 23, a reservoir 24, a wheel cylinder 25, and wheels 26.

[0022] The vehicle 10 has, for example, four wheels 26. The brake system 20 controls the braking force acting on each wheel 26 by controlling the hydraulic pressure (i.e., wheel cylinder pressure) of the wheel cylinder 25 provided on each of these wheels 26. In order to facilitate understanding, FIG. 2 shows only the parts of the brake system 20 that relate to one of the two wheels 26 corresponding to the front wheels and the two wheels 26 corresponding to the rear wheels, and omits the parts that relate to the other wheels. Note that the number of wheels 26 may be other than four.

[0023] The brake pedal 21 is used by the driver to apply the brakes. When applying the brakes, the driver depresses the brake pedal 21. The electric booster 22 is connected to the brake pedal 21 and works in conjunction with the brake pedal 21 to amplify the force applied to the brake pedal 21. Specifically, the electric booster 22 incorporates a piston that reciprocates in conjunction with the brake pedal 21, and is connected to a master cylinder 23. As the piston moves in response to the brake application, the master cylinder pressure, which is the hydraulic pressure in the master cylinder 23, is increased. In this way, the electric booster 22 can generate master cylinder pressure in accordance with the amount of brake application. The reservoir 24 is attached to the master cylinder 23 and stores brake fluid.

[0024] Here, the electric booster 22 is electrically operable. Therefore, by operating the electric booster 22 (specifically, a piston) using electric power, it is possible to assist the depression force on the brake pedal 21. In addition, by operating the electric booster 22 (specifically, a piston) using electric power, it is possible to increase the master cylinder pressure without requiring a brake operation, thereby automatically increasing the wheel cylinder pressure.

[0025] The hydraulic pressure control unit 13 includes a base 13a in which a flow path for brake fluid is formed. The master cylinder 23 and each wheel cylinder 25 are connected to the base 13a of the hydraulic pressure control unit 13. When the wheel cylinder pressure, which is the hydraulic pressure in the wheel cylinder 25, increases, the brake pads (not shown) operate to press against the brake discs (not shown), thereby applying a braking force corresponding to the wheel cylinder pressure to the wheels 26.

[0026] The base body 13a of the hydraulic control unit 13 is formed with brake fluid flow paths, including a main flow path 31, a sub-flow path 32, and a supply flow path 33. The main flow path 31 distributes the brake fluid in the master cylinder 23 to the wheel cylinders 25. The sub-flow path 32 releases the brake fluid in the wheel cylinders 25. The supply flow path 33 supplies the brake fluid in the master cylinder 23 to the sub-flow path 32.

[0027] In addition, the base 13a of the hydraulic control unit 13 is provided with components for controlling the braking force generated on each wheel 26, including an inlet valve (EV) 41, a release valve (AV) 42, a first valve (USV) 43, a second valve (HSV) 44, an accumulator 45, a pump 46, and a motor 47.

[0028] The main flow path 31 connects the master cylinder 23 and the wheel cylinders 25. The main flow path 31 includes one first main flow path 31a and two second main flow paths 31b. The first main flow path 31a is connected to the master cylinder 23. The two second main flow paths 31b branch off from the first main flow path 31a and are connected to the wheel cylinders 25, respectively. A first valve 43 is provided in the first main flow path 31a. An inlet valve 41 is provided in the second main flow path 31b.

[0029] The sub-path 32 communicates the wheel cylinder 25 side of the main path 31 relative to the inlet valve 41 with the master cylinder 23 side of the main path 31 relative to the inlet valve 41 and the wheel cylinder 25 side of the first valve 43. The sub-path 32 includes two first sub-paths 32a and one second sub-path 32b. Each first sub-path 32a is connected to the wheel cylinder 25 side of the main path 31 relative to the inlet valve 41. The second sub-path 32b connects the junction of the two first sub-paths 32a with the master cylinder 23 side of the main path 31 relative to the inlet valve 41 and the wheel cylinder 25 side of the first valve 43. A release valve 42 is provided in the first sub-path 32a. An accumulator 45 and a pump 46 are provided in the second sub-path 32b, in this order from the first sub-path 32a side.

[0030] The pump 46 is driven by the motor 47 and sucks brake fluid from the first sub-channel 32a and discharges it to the main channel 31. The pump 46 is a reciprocating plunger pump. Specifically, the plunger of the pump 46 is intermittently pressed by an eccentric cam provided on the output shaft of the motor 47, thereby causing the pump 46 to pump and deliver brake fluid.

[0031] The supply flow path 33 communicates the master cylinder 23 side of the first valve 43 in the main flow path 31 with the suction side of the pump 46 in the sub-flow path 32. A second valve 44 is provided in the supply flow path 33.

[0032] The inlet valve 41 is, for example, a solenoid valve that is open in a de-energized state and closed in a powered state. The release valve 42 is, for example, a solenoid valve that is closed in a de-energized state and open in a powered state. The first valve 43 is, for example, a solenoid valve that is open in a de-energized state and closed in a powered state. The second valve 44 is, for example, a solenoid valve that is closed in a de-energized state and open in a powered state. By controlling the operation of these valves and the motor 47, the braking force acting on each wheel 26 is controlled.

[0033] The hydraulic control unit 13 is provided with wheel cylinder pressure sensors 48. The wheel cylinder pressure sensors 48 are provided for the respective wheel cylinders 25 and detect the hydraulic pressure (i.e., wheel cylinder pressure) of the respective wheel cylinders 25. The wheel cylinder pressure sensors 48 detect, for example, the hydraulic pressure near the confluence of the first sub-path 32a and the second main path 31b as the wheel cylinder pressure.

[0034] For example, during normal operation when antilock brake control (described later) or the like is not being executed, inlet valve 41 is open, release valve 42 is closed, first valve 43 is open, and second valve 44 is closed. This allows brake fluid to flow from master cylinder 23 to wheel cylinders 25 only through main flow path 31, without passing through sub-flow path 32 and supply flow path 33. When brake pedal 21 is depressed in this state, the master cylinder pressure is increased, which in turn increases wheel cylinder pressure, thereby applying braking force to wheels 26.

[0035] Furthermore, for example, when anti-lock brake control, which is a control for preventing the wheels 26 from locking, is executed, first, the inlet valve 41 is closed, the release valve 42 is opened, the first valve 43 is opened, and the second valve 44 is closed. This stops the flow of brake fluid between the main flow path 31 and the wheel cylinders 25, allowing brake fluid to flow from the wheel cylinders 25 to the secondary flow path 32. Therefore, brake fluid flows from the wheel cylinders 25 to the accumulator 45, reducing the wheel cylinder pressure and the braking force applied to the wheels 26. The brake fluid that has flowed into the accumulator 45 is returned to the main flow path 31 via the secondary flow path 32 by driving the pump 46.

[0036] Then, from the above state, both the inlet valve 41 and the release valve 42 are closed, stopping the flow of brake fluid between the main flow path 31 and the sub-flow path 32 and the wheel cylinders 25, maintaining the wheel cylinder pressure and maintaining the braking force applied to the wheels 26. Thereafter, the inlet valve 41 is opened and the release valve 42 is closed, restarting the flow of brake fluid between the main flow path 31 and the wheel cylinders 25, increasing the wheel cylinder pressure and increasing the braking force applied to the wheels 26.

[0037] Here, the hydraulic control unit 13 can also automatically increase the wheel cylinder pressure without requiring a brake operation. For example, when automatically increasing the wheel cylinder pressure without requiring a brake operation, the inlet valve 41 is opened, the release valve 42 is closed, the first valve 43 is closed, and the second valve 44 is opened. This allows brake fluid to flow from the master cylinder 23 to the wheel cylinder 25 via the supply flow path 33 and the sub-flow path 32. In this state, the pump 46 is driven to increase the wheel cylinder pressure, generating a braking force that brakes the wheel 26.

[0038] 3 is a block diagram showing an example of the functional configuration of the control device 16. The control device 16 may be, for example, a single device or may be divided into multiple devices. When the control device 16 is divided into multiple devices, the various functions described below are shared among the multiple devices, so that, for example, some functions of the control unit 16b described below and other functions may be shared by different devices.

[0039] As shown in FIG. 3, the control device 16 includes, for example, an acquisition unit 16a and a control unit 16b.

[0040] The acquisition unit 16a acquires information from each device in the vehicle 10. For example, the acquisition unit 16a acquires information from the ambient environment sensor 14, the wheel speed sensor 15, and the wheel cylinder pressure sensor 48. In this specification, the acquisition of information may include the extraction or generation (e.g., calculation) of information.

[0041] The control unit 16b controls the operation of each device in the vehicle 10. For example, the control unit 16b controls the operation of the steering mechanism 11, the drive source 12, the hydraulic control unit 13, and the electric booster 22.

[0042] The control unit 16b can perform various types of control to automatically control the traveling of the vehicle 10 by taking over part or all of the driving operations by the driver, for example, by controlling the steering mechanism 11, the drive source 12, the hydraulic control unit 13, and the electric booster 22. Examples of such control include automatic parking control and adaptive cruise control.

[0043] The automatic parking control is a control for automatically parking the vehicle 10. For example, in the automatic parking control, the control unit 16b uses the detection results of the surrounding environment sensor 14 to recognize obstacles around the vehicle 10 and the parking target position, and automatically drives the vehicle 10 to the parking target position while avoiding contact with the obstacles. This allows the driver to park the vehicle 10 while inside the vehicle 10 without performing any driving operations.

[0044] Adaptive cruise control is a control for maintaining a constant inter-vehicle distance between the vehicle 10 and a preceding vehicle. For example, the control unit 16b uses the detection results of the surrounding environment sensor 14 to identify the inter-vehicle distance between the vehicle 10 and the preceding vehicle, and automatically drives the vehicle 10 so that the inter-vehicle distance is maintained at a target distance.

[0045] <Control device operation> The operation of the control device 16 according to the embodiment of the present invention will be described with reference to FIGS.

[0046] As described above, the control unit 16b of the control device 16 can execute various types of control (for example, automatic parking control or adaptive cruise control) that automatically control the traveling of the vehicle 10. In these controls, the control unit 16b controls the speed of the vehicle 10. For example, the control unit 16b uses the detection results of the wheel speed sensors 15 to identify the speed of the vehicle 10, and controls the driving force and braking force of the vehicle 10 so that the speed becomes a target speed.

[0047] Here, the control unit 16b executes pressure increase control to automatically increase the wheel cylinder pressure without relying on the brake operation by the driver when automatically braking the vehicle 10. The control unit 16b executes pressure increase control by switching between first pressure increase control to automatically increase the wheel cylinder pressure using the electric booster 22 and second pressure increase control to automatically increase the wheel cylinder pressure using the pump 46.

[0048] In the first pressure increase control, the control unit 16b controls the hydraulic control unit 13 to a state in which the inlet valve 41 is open, the release valve 42 is closed, the first valve 43 is open, and the second valve 44 is closed. This allows the brake fluid to flow from the master cylinder 23 to the wheel cylinders 25 only through the main flow path 31, without passing through the sub-flow path 32 or the supply flow path 33. In this state, the control unit 16b increases the master cylinder pressure by operating the electric booster 22 (specifically, the piston) using electric power. This automatically increases the wheel cylinder pressure.

[0049] In the second pressure increase control, the control unit 16b controls the hydraulic control unit 13 to a state in which the inlet valve 41 is open, the release valve 42 is closed, the first valve 43 is closed, and the second valve 44 is open. This allows brake fluid to flow from the master cylinder 23 to the wheel cylinders 25 via the supply flow path 33 and the sub-flow path 32. In this state, the control unit 16b uses electric power to operate the motor 47, thereby driving the pump 46. This automatically increases the wheel cylinder pressure.

[0050] Here, the execution of pressure increase control can be a factor that reduces driver comfort. For example, when the first pressure increase control is executed, the brake pedal 21 moves in conjunction with the electric booster 22. If the brake pedal 21 moves in this manner even though no braking operation is being performed, the driver may feel uncomfortable. Furthermore, when the second pressure increase control is executed, for example, the driver may feel less comfortable due to noise and vibrations that occur when the pump 46 is driven. Therefore, in this embodiment, by implementing a process for automatically increasing the wheel cylinder pressure, it is possible to suppress the reduction in driver comfort. An example of the process executed by the control device 16 will be described in detail below.

[0051] Fig. 4 is a flowchart showing an example of the flow of processing performed by the control device 16. Step S101 in Fig. 4 corresponds to the start of the processing flow shown in Fig. 4. Step S111 in Fig. 4 corresponds to the end of the processing flow shown in Fig. 4.

[0052] 4 starts when an automatic pressure increase request is generated, which is a request to automatically increase the wheel cylinder pressure in order to automatically brake the vehicle 10, during the execution of various controls (e.g., automatic parking control, adaptive cruise control, etc.) that automatically control the traveling of the vehicle 10. For example, during various controls that automatically control the traveling of the vehicle 10, the automatic pressure increase request is generated when the control unit 16b determines that it is necessary to automatically brake the vehicle 10.

[0053] 4 starts, the control unit 16b determines whether the wheel cylinder pressure is lower than the second threshold value in step S102. The acquisition unit 16a can acquire information indicating the wheel cylinder pressure based on the detection result of the wheel cylinder pressure sensor 48, for example.

[0054] The second threshold value is smaller than the first threshold value described below. The second threshold value is set to a value small enough to determine whether or not a braking force is being applied to the wheel 26. If the wheel cylinder pressure is lower than the second threshold value, it can be determined that no braking force is being applied to the wheel 26 (i.e., the brake pads are not pressed against the brake disc). On the other hand, if the wheel cylinder pressure is higher than the second threshold value, it can be determined that a braking force is being applied to the wheel 26 (i.e., the brake pads are pressed against the brake disc).

[0055] If it is determined that the wheel cylinder pressure is lower than the second threshold (step S102 / YES), the process proceeds to step S103. On the other hand, if it is determined that the wheel cylinder pressure is higher than the second threshold (step S102 / NO), the process proceeds to step S108.

[0056] If the determination in step S102 is YES, the control unit 16b starts the first pressure increase control (that is, pressure increase control using the electric booster 22) in step S103.

[0057] Next, in step S104, the control unit 16b determines whether the automatic pressure increase request has been canceled. For example, in various controls that automatically control the traveling of the vehicle 10, if the control unit 16b determines that the braking force of the vehicle 10 has reached the target braking force or that it is no longer necessary to brake the vehicle 10, the automatic pressure increase request is canceled.

[0058] If it is determined that the automatic pressure increase request has been canceled (step S104 / YES), the process proceeds to step S105. In step S105, the control unit 16b ends the first pressure increase control, and the process flow shown in Fig. 4 ends. On the other hand, if it is determined that the automatic pressure increase request has not been canceled (step S104 / NO), the process proceeds to step S106.

[0059] If the determination in step S104 is NO, the control unit 16b determines in step S106 whether the wheel cylinder pressure has exceeded a first threshold value. Details of the first threshold value will be described later.

[0060] If it is determined that the wheel cylinder pressure does not exceed the first threshold (step S106 / NO), the process returns to step S104. That is, in this case, the first pressure-increasing control continues. On the other hand, if it is determined that the wheel cylinder pressure exceeds the first threshold (step S106 / YES), the process proceeds to step S107.

[0061] If the determination in step S106 is YES, in step S107, the control unit 16b ends the first pressure-increase control. Next, in step S108, the control unit 16b starts the second pressure-increase control (i.e., pressure-increase control using the pump 46). That is, in this case, the first pressure-increase control ends and the second pressure-increase control starts.

[0062] As described above, the control unit 16b executes the first pressure-increase control when the wheel cylinder pressure is lower than the first threshold, and ends the first pressure-increase control and starts the second pressure-increase control when the wheel cylinder pressure exceeds the first threshold. This narrows the circumstances in which the second pressure-increase control is executed compared to when only the second pressure-increase control using the pump 46 is executed as the pressure-increase control. This makes it possible to suppress a decrease in comfort due to noise and vibrations generated by driving the pump 46.

[0063] If the second pressure-increase control is started when no braking force is being applied to the wheel 26 (i.e., the brake pads are not pressed against the brake disc), loud noise and vibrations are likely to occur when the brake pads collide with the brake disc. In this regard, by executing the first pressure-increase control prior to the second pressure-increase control, the occurrence of such loud noise and vibrations can be suppressed.

[0064] However, when only the first pressure-boosting control using the electric booster 22 is executed as the pressure-boosting control, it is possible to suppress a decrease in comfort due to noise and vibrations generated by driving the pump 46, but the driver is likely to feel uncomfortable due to the movement of the brake pedal 21 in conjunction with the electric booster 22. Therefore, by switching between the first pressure-boosting control and the second pressure-boosting control as described above, it is possible to suppress such discomfort and effectively suppress a decrease in driver comfort.

[0065] Here, the first threshold value in step S106, which is used as a parameter for determining the timing of switching between the first pressure-increase control and the second pressure-increase control, will be described with reference to Fig. 5. Fig. 5 is a diagram showing an example of a movable range R1 of the brake pedal 21. As shown in Fig. 5, in addition to the brake pedal 21, the vehicle 10 is also provided with an accelerator pedal 51 that accepts accelerator operation by the driver. The accelerator operation is an operation of depressing the accelerator pedal 51.

[0066] As shown in FIG. 5 , the brake pedal 21 is rotatable about a rotation axis A1. In the example of FIG. 5 , for ease of understanding, the accelerator pedal 51 is rotatable about a rotation axis that is disposed approximately coaxially with the rotation axis A1 of the brake pedal 21. However, the rotation axis of the accelerator pedal 51 does not have to be disposed coaxially with the rotation axis A1 of the brake pedal 21. Here, the brake pedal 21 and the accelerator pedal 51 refer to flat plate-shaped parts that are stepped on by the driver's foot. For example, when viewed in the axial direction of the rotation axis A1, the rotation axis A1 is located at the end of a rod-shaped member that is connected to the brake pedal 21 and moves integrally with the brake pedal 21. For example, when viewed in the axial direction of the rotation axis, the rotation axis of the accelerator pedal 51 is located at the end of a rod-shaped member that is connected to the accelerator pedal 51 and moves integrally with the accelerator pedal 51.

[0067] When the driver depresses the brake pedal 21, the brake pedal 21 moves within a movable range R1 from a reference position P1 to a limit position P2. In the example of FIG. 5, the movable range R1 is an arc-shaped range centered on the rotation axis A1. When the brake pedal 21 is not depressed by the driver and is in an unloaded state, the brake pedal 21 is located at a reference position P1. The reference position P1 is, for example, the position closest to the driver within the movable range R1. When the driver depresses the brake pedal 21 and the brake pedal 21 reaches a limit position P2, the brake pedal 21 cannot move any further. The limit position P2 is, for example, the position farthest from the driver within the movable range R1. Note that the accelerator pedal 51 also moves within the arc-shaped movable range when depressed by the driver.

[0068] As described above, the first pressure-increase control is a control that automatically increases the wheel cylinder pressure without requiring a brake operation. Therefore, the first pressure-increase control is initiated in an unloaded state in which the brake pedal 21 is not depressed by the driver. That is, when the first pressure-increase control is initiated, the brake pedal 21 is located at the reference position P1. Then, during the execution of the first pressure-increase control, as the wheel cylinder pressure increases, the brake pedal 21 moves within the movable range R1 from the reference position P1 toward the limit position P2.

[0069] Here, when the wheel cylinder pressure is lower than the first threshold value during execution of the first pressure-increase control, the brake pedal 21 is located at a position P3 within the movable range R1 on the reference position P1 side (i.e., on the driver's side) relative to the accelerator pedal 51, as shown in FIG. 5. Under conditions in which the first pressure-increase control is being executed, the accelerator pedal 51 is basically not being depressed by the driver. For example, the position of the accelerator pedal 51 shown in FIG. 5 is the position in an unloaded state in which the accelerator pedal 51 is not being depressed by the driver. Therefore, when the wheel cylinder pressure is lower than the first threshold value during execution of the first pressure-increase control, the brake pedal 21 is located within the movable range R1 on the reference position P1 side relative to the accelerator pedal 51, as indicated by the two-dot chain line in FIG. 5.

[0070] When neither the brake pedal 21 nor the accelerator pedal 51 is being operated, the brake pedal 21 is located within the movable range R1 on the reference position P1 side (i.e., on the driver's side) relative to the accelerator pedal 51. In other words, in such a situation, the brake pedal 21 is closer to the driver than the accelerator pedal 51. Here, if the brake pedal 21 were to move to the limit position P2 side (i.e., on the opposite side from the driver) relative to the accelerator pedal 51 within the movable range R1 during execution of the first pressure-increase control, the accelerator pedal 51 would be closer to the driver than the brake pedal 21. This phenomenon would cause the driver to feel a great sense of discomfort and could even lead to the driver mistaking the accelerator pedal 51 for the brake pedal 21 and depressing it. Therefore, when the wheel cylinder pressure is lower than the first threshold value during execution of the first pressure-increase control, by positioning the brake pedal 21 within the movable range R1 on the reference position P1 side (i.e., on the driver's side) relative to the accelerator pedal 51, it is possible to effectively reduce the discomfort felt by the driver and further reduce a decrease in safety.

[0071] 4, if the determination in step S102 is NO (i.e., if it is determined that the wheel cylinder pressure is higher than the second threshold value), the process proceeds to step S108 without proceeding to step S103. That is, in this case, the first pressure-increase control is not started, but the second pressure-increase control is started.

[0072] As described above, the control unit 16b starts the first pressure increase control when the wheel cylinder pressure is lower than the second threshold value which is smaller than the first threshold value at the start of automatic pressure increase of the wheel cylinder pressure, and starts the second pressure increase control without starting the first pressure increase control when the wheel cylinder pressure is higher than the second threshold value at the start of automatic pressure increase of the wheel cylinder pressure.

[0073] As described above, if the second pressure-increase control is initiated when no braking force is being applied to the wheels 26 (i.e., the brake pads are not pressed against the brake discs), loud noise and vibration are likely to occur when the brake pads collide with the brake discs. On the other hand, if the second pressure-increase control is initiated when braking force is being applied to the wheels 26 (i.e., the brake pads are pressed against the brake discs), such noise and vibration will not occur. Therefore, in a situation where the wheel cylinder pressure is higher than the second threshold value at the start of automatic pressure-increase of the wheel cylinder pressure (i.e., when braking force is being applied to the wheels 26), there is little need to suppress the decrease in comfort caused by noise and vibration that occurs with the second pressure-increase control. Therefore, by starting the second pressure-increase control without starting the first pressure-increase control, it is possible to effectively suppress the discomfort that the first pressure-increase control causes to the driver.

[0074] After step S108 in FIG. 4, in step S109, the control unit 16b determines whether the automatic pressure increase request has been cancelled.

[0075] If it is determined that the automatic pressure increase request has not been cancelled (step S109 / NO), step S109 is repeated. On the other hand, if it is determined that the automatic pressure increase request has been cancelled (step S109 / YES), the process proceeds to step S110. In step S110, the control unit 16b ends the second pressure increase control, and the process flow shown in FIG. 4 ends.

[0076] The above describes an example of the processing performed by the control device 16. However, the processing performed by the control device 16 is not limited to the above example of processing, and may be, for example, a processing obtained by appropriately modifying the above example of processing.

[0077] For example, in the above example, the control unit 16b determines whether the wheel cylinder pressure has exceeded the first threshold value in step S106. However, in step S106, the control unit 16b may make the determination using a parameter other than the wheel cylinder pressure, as long as it can determine whether the wheel cylinder pressure has exceeded the first threshold value. For example, in step S106, the control unit 16b may determine whether the master cylinder pressure has exceeded the first threshold value, assuming that the master cylinder pressure is approximately equal to the wheel cylinder pressure. Also, in step S106, for example, the control unit 16b may use the stroke amount of the brake pedal 21 as a parameter for estimating the wheel cylinder pressure, and determine whether the stroke amount has exceeded a value corresponding to the first threshold value.

[0078] Also, for example, in the above description, the control unit 16b determines whether the wheel cylinder pressure is lower than the second threshold value in step S102. However, in step S102, the control unit 16b may make the determination using a parameter other than the wheel cylinder pressure, as long as it can determine whether the wheel cylinder pressure is lower than the second threshold value. For example, in step S102, the control unit 16b may determine whether the master cylinder pressure is lower than the second threshold value, assuming that the master cylinder pressure is approximately equal to the wheel cylinder pressure. Also, for example, in step S102, the control unit 16b may use the stroke amount of the brake pedal 21 as a parameter for estimating the wheel cylinder pressure, and determine whether the stroke amount is smaller than a value corresponding to the second threshold value.

[0079] In the above example, the control unit 16b starts the second pressure-increase control without starting the first pressure-increase control when the wheel cylinder pressure is higher than the second threshold value at the start of automatic pressure-increase of the wheel cylinder pressure. However, the control unit 16b may start the first pressure-increase control regardless of whether the wheel cylinder pressure is lower than the second threshold value at the start of automatic pressure-increase of the wheel cylinder pressure. For example, step S102 may be omitted from the example of FIG. 4.

[0080] Also, for example, in the above description, when the wheel cylinder pressure is lower than the first threshold value during execution of the first pressure-increase control, the brake pedal 21 is positioned on the reference position P1 side of the movable range R1 relative to the accelerator pedal 51. However, when the wheel cylinder pressure is lower than the first threshold value during execution of the first pressure-increase control but is high enough to almost match the first threshold value, the brake pedal 21 may be positioned on the limit position P2 side of the movable range R1 relative to the accelerator pedal 51.

[0081] In addition, for example, in the above example, the brake pedal 21 is rotatable. However, the movement direction of the brake pedal 21 is not limited to the above example. For example, the brake pedal 21 may be movable in a parallel direction.

[0082] Furthermore, for example, in the above description, the electric booster 22 has been described as a pressure booster that automatically boosts the wheel cylinder pressure by boosting the master cylinder pressure and that operates in conjunction with the brake pedal 21. However, the pressure booster is not limited to the electric booster 22. For example, the pressure booster may be driven using energy other than electric power. For example, the pressure booster may not have a built-in piston.

[0083] <Effects of the control device> The effects of the control device 16 according to the embodiment of the present invention will be described.

[0084] The control device 16 is a control device for the vehicle 10 that includes a pressure increase device (electric booster 22 in the above example) that automatically increases the wheel cylinder pressure, which is the hydraulic pressure in the wheel cylinders 25, by increasing the master cylinder pressure, which is the hydraulic pressure in the master cylinder 23, and that operates in conjunction with the brake pedal 21, and a pump 46 that automatically increases the wheel cylinder pressure by supplying brake fluid from the master cylinder 23 to the wheel cylinders 25. The control device 16 includes a control unit 16b that switches between first pressure increase control that automatically increases the wheel cylinder pressure using the pressure increase device and second pressure increase control that automatically increases the wheel cylinder pressure using the pump 46. When automatically increasing the wheel cylinder pressure, the control unit 16b starts the first pressure increase control, and when the wheel cylinder pressure exceeds a first threshold, ends the first pressure increase control and starts the second pressure increase control. This narrows the situations in which the second pressure increase control is performed compared to when only the second pressure increase control using the pump 46 is performed as the pressure increase control. This makes it possible to suppress a decrease in comfort caused by noise and vibrations that occur when the pump 46 is driven. Furthermore, compared to when only the first pressure-boosting control using the electric booster 22 is executed as the pressure-boosting control, it is also possible to suppress the discomfort felt by the driver due to the brake pedal 21 moving in conjunction with the electric booster 22. Therefore, by switching between the first pressure-boosting control and the second pressure-boosting control as described above, it is possible to suppress a decrease in comfort felt by the driver.

[0085] Preferably, in the control device 16, the control unit 16b starts the first pressure-increase control when the wheel cylinder pressure is lower than a second threshold value that is lower than the first threshold value at the start of automatic pressure-increase of the wheel cylinder pressure, and starts the second pressure-increase control without starting the first pressure-increase control when the wheel cylinder pressure is higher than the second threshold value at the start of automatic pressure-increase of the wheel cylinder pressure. As a result, by starting the second pressure-increase control without starting the first pressure-increase control under conditions where the wheel cylinder pressure is higher than the second threshold value at the start of automatic pressure-increase of the wheel cylinder pressure and there is little need to suppress a decrease in comfort due to noise and vibrations generated by the second pressure-increase control, it is possible to effectively suppress the discomfort that the driver may experience due to the first pressure-increase control.

[0086] Preferably, in the control device 16, when the driver depresses the brake pedal 21, the brake pedal 21 moves from the reference position P1 within the movable range R1, and when the wheel cylinder pressure is lower than the first threshold value while the first pressure-increase control is being executed, the brake pedal 21 is positioned on the reference position P1 side of the movable range R1 relative to the accelerator pedal 51. This prevents the accelerator pedal 51 from being closer to the driver than the brake pedal 21 while the first pressure-increase control is being executed, thereby effectively reducing any discomfort felt by the driver and further reducing a decrease in safety.

[0087] The above describes a preferred embodiment of the present invention with reference to the accompanying drawings. However, it goes without saying that the present invention is not limited to the above-described embodiment, and various modified or altered examples within the scope of the claims also fall within the technical scope of the present invention.

[0088] For example, the processes described herein using flowcharts do not necessarily have to be performed in the order shown in the flowcharts, some process steps may be performed in parallel, additional process steps may be employed, and some process steps may be omitted.

[0089] Furthermore, for example, the series of processes performed by the control device 16 described above may be realized using software, hardware, or a combination of software and hardware. The programs constituting the software are stored in advance in, for example, a storage medium provided inside or outside the information processing device. [Explanation of symbols]

[0090] 10 vehicles 11 Steering mechanism 12 Power Source 13 Hydraulic control unit 14 Ambient environment sensor 15 Wheel speed sensor 16 Control device 16a Acquisition part 16b Control section 20 Brake System 21 Brake pedal 22 Electric booster (pressure booster) 23 Master cylinder 24 reservoir 25 Wheel cylinder 26 wheels 31 Main channel 32 Subchannel 33 Supply channel 41 Inlet valve 42 Release valve 43 First Valve 44 Second valve 45 Accumulator 46 Pump 47 Motor 48 Wheel cylinder pressure sensor 51 Accelerator pedal A1 Rotation axis P1 reference position P2 limit position P3 position R1 range of motion

Claims

1. A control device (16) for a vehicle (10) including: a pressure booster (22) that automatically boosts a wheel cylinder pressure, which is the hydraulic pressure in a wheel cylinder (25), by boosting a master cylinder pressure, which is the hydraulic pressure in a master cylinder (23), and that operates in conjunction with a brake pedal (21); and a pump (46) that automatically boosts the wheel cylinder pressure by supplying brake fluid from the master cylinder (23) to the wheel cylinder (25), a control unit (16b) that switches between a first pressure increase control that automatically increases the wheel cylinder pressure using the pressure increase device (22) and a second pressure increase control that automatically increases the wheel cylinder pressure using the pump (46), the control unit (16b) starts the first pressure-increasing control when automatically increasing the wheel cylinder pressure, and ends the first pressure-increasing control and starts the second pressure-increasing control under a condition in which the wheel cylinder pressure exceeds a first threshold value. Control device.

2. The control unit (16b) the first pressure increase control is started under a condition in which the wheel cylinder pressure is lower than a second threshold value that is smaller than the first threshold value when the automatic increase in the wheel cylinder pressure is started; When the wheel cylinder pressure is higher than the second threshold value at the start of the automatic increase in the wheel cylinder pressure, the first pressure increase control is not started but the second pressure increase control is started. The control device according to claim 1 .

3. When the brake pedal (21) is depressed by the driver, it moves from a reference position (P1) within a movable range (R1), When the wheel cylinder pressure is lower than the first threshold value during execution of the first pressure increase control, the brake pedal (21) is positioned on the reference position (P1) side of the movable range (R1) relative to the accelerator pedal (51). The control device according to claim 1 or 2.

4. A control method for a vehicle (10) comprising: a pressure booster (22) that automatically boosts a wheel cylinder pressure, which is the hydraulic pressure in a wheel cylinder (25), by boosting a master cylinder pressure, which is the hydraulic pressure in a master cylinder (23), and that operates in conjunction with a brake pedal (21); and a pump (46) that automatically boosts the wheel cylinder pressure by supplying brake fluid from the master cylinder (23) to the wheel cylinder (25), a control unit (16b) of the control device (16) selectively executes a first pressure increase control for automatically increasing the wheel cylinder pressure using the pressure increase device (22) and a second pressure increase control for automatically increasing the wheel cylinder pressure using the pump (46); the control unit (16b) starts the first pressure-increasing control when automatically increasing the wheel cylinder pressure, and ends the first pressure-increasing control and starts the second pressure-increasing control under a condition in which the wheel cylinder pressure exceeds a first threshold value. Control method.

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