Vehicle braking system

Abstract

To enhance operability of brake operation for obtaining brake force of target.SOLUTION: A brake system 12 contains an EMB system 14 and a hydraulic brake system 16 and generates brake force on a vehicle according to brake operation. A brake characteristic change part 30 changes characteristics of the brake force against the brake operation. In addition, a brake device 10 for a vehicle contains a brake pedal 18 and a manual brake operation device 20 and switches between brake operation by the manual brake operation device 20 and brake operation by the brake pedal 18 by switching operation by a driver.SELECTED DRAWING: Figure 1

Description

Technical Field

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[0001] The present disclosure relates to a braking device for a vehicle capable of manual brake operation.

Background Art

[0002] Vehicles capable of manual brake operation are known.

[0003] In the vehicle described in Patent Document 1, a brake lever is arranged near the steering wheel.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0008] According to this disclosure, it is possible to improve the operability of the brake operation to obtain the target braking force. [Brief explanation of the drawing]

[0009] [Figure 1] This is a block diagram showing the configuration of a vehicle braking system according to an embodiment. [Figure 2] This is a flowchart illustrating the operation of a vehicle braking system according to an embodiment. [Modes for carrying out the invention]

[0010] Figure 1 shows the configuration of a vehicle braking system 10 according to an embodiment. The vehicle braking system 10 is mounted on a vehicle and generates braking force in response to the driver's request.

[0011] The vehicle braking system 10 includes an EMB (Electro Mechanical Brake) system 14 and a hydraulic brake system 16 as a brake system 12. The brake system 12 is configured as a drive-by-wire system. In other words, the brake system 12 electrically detects the driver's braking operation and generates braking force based on the detection result. Furthermore, the brake system 12 is an electric brake system that generates braking force using a motor, and generates braking force by controlling the motor's driving force based on the required braking force (target braking force).

[0012] Either the front or rear wheel brake system is an EMB system 14, and the other brake system is a hydraulic brake system 16. In the following example, the front wheel brake system is a hydraulic brake system 16, and the rear wheel brake system is an EMB system 14.

[0013] The EMB system 14 generates braking force without using hydraulic pressure and supplies the braking force directly to the brake pads via a motor. The brake pads are an example of a friction component. The EMB system 14 corresponds to an example of a first brake system.

[0014] The hydraulic brake system 16 includes an electric brake booster and generates braking force corresponding to the hydraulic pressure supplied to the front wheels. Specifically, the hydraulic brake system 16 converts the motor's driving force into hydraulic pressure and supplies it to the brake pads. The hydraulic brake system 16 is an example of a second brake system.

[0015] The vehicle braking system 10 also includes a brake pedal 18 and a manual brake operating device 20. The brake pedal 18 is a device for operating the brakes by the force applied when stepping on it. The manual brake operating device 20 is a device for operating the brakes manually. For example, the manual brake operating device 20 is a brake lever located near the steering wheel.

[0016] The brake control device 22 controls the braking force of the EMB system 14 and the hydraulic brake system 16 in accordance with the driver's brake operation. For example, the brake control device 22 changes the braking force of the EMB system 14 and the hydraulic brake system 16 according to the stroke amount of the brake pedal 18. Alternatively, the brake control device 22 changes the braking force of the EMB system 14 and the hydraulic brake system 16 according to the amount of operation of the manual brake operating device 20. The brake control device 22 may generate braking force by controlling either the EMB system 14 or the hydraulic brake system 16, or it may generate braking force by controlling both the EMB system 14 and the hydraulic brake system 16.

[0017] The switching unit 24 switches between brake operation by the brake pedal 18 and brake operation by the manual brake operating device 20.

[0018] The switching operation unit 26 is a button or switch for instructing the switching of brake operation. For example, the switching of brake operation can be instructed by turning the button or switch on or off. When the button is on, the manual brake operation device 20 is selected, and when the button is off, the brake pedal 18 is selected.

[0019] When the driver operates the switching unit 26 to select the brake pedal 18, the switching unit 24 switches the braking operation to braking using the brake pedal 18. This allows the driver to perform the braking operation using the brake pedal 18.

[0020] When the driver operates the switching unit 26 to select the manual brake control device 20, the switching unit 24 switches the brake operation to the manual brake control device 20. This allows the driver to perform the brake operation using the manual brake control device 20.

[0021] For example, after turning on the ignition switch, the driver selects either the brake pedal 18 or the manual brake operating device 20.

[0022] The road surface information acquisition unit 28 includes detection devices such as a radar and a camera, and acquires road surface information indicating the state of the road surface. For example, the road surface information acquisition unit 28 irradiates the road surface with a radar or takes a picture of the road surface with a camera to detect the state of the road surface and objects on the road surface. The state of the road surface is, for example, dry, wet, snow-covered, frozen, presence or absence of sand, presence or absence of oil, and muddy. For example, the road surface information acquisition unit 28 calculates the friction coefficient μ of the road surface based on the information acquired by the radar, camera, etc.

[0023] The brake characteristic change unit 30 changes the brake characteristics of the brake system 12. A plurality of brake characteristics are preset in the vehicle braking device 10, and the brake characteristic change unit 30 selects a brake characteristic corresponding to the driver's preference and the state of the road surface from among the plurality of brake characteristics. The brake system 12 generates a braking force according to the selected brake characteristic.

[0024] For example, when the friction coefficient μ of the road surface is less than the threshold value, the brake characteristic change unit 30 selects the low μ mode as the brake characteristic. When the brake operation is performed by the brake pedal 18, the low μ mode is a mode in which the stroke amount of the brake pedal 18 with respect to the target braking force becomes smaller. When the brake operation is performed by the manual brake operating device 20, the low μ mode is a mode in which the operation amount of the manual brake operating device 20 with respect to the target braking force becomes smaller. In the low μ mode, the braking effect is improved with a short stroke amount or operation amount.

[0025] When the friction coefficient μ of the road surface is greater than or equal to the threshold value, the brake characteristic change unit 30 selects a normal mode different from the low μ mode. The normal mode is a mode in which the stroke amount and operation amount with respect to the target braking force are larger than those in the low μ mode.

[0026] Furthermore, the brake characteristic changing unit 30 may select brake characteristics according to the driver's instructions. For example, a switch or button for changing brake characteristics may be provided near the steering wheel. Multiple brake characteristics with different stroke amounts and operating amounts relative to the target braking force are pre-set in the vehicle braking system 10, and the driver can select a brake characteristic from among these multiple brake characteristics by operating a switch or button. For example, the driver can select a low-μ mode or a normal mode by operating a switch or button.

[0027] The operation of the vehicle braking system 10 will be explained below with reference to Figure 2. Figure 2 is a flowchart showing the flow of its operation.

[0028] First, the driver turns the ignition switch ON (IG-ON).

[0029] If the manual brake operating device 20 is not selected by the switching operation unit 26 (S01, No) (i.e., the brake pedal 18 is selected), the brake operation is performed using the brake pedal 18 (S02).

[0030] When the driver starts driving (S03), the road surface information acquisition unit 28 acquires road surface information (S04) and calculates the friction coefficient μ of the road surface.

[0031] The brake characteristic changing unit 30 selects brake characteristics according to the road surface conditions (for example, the friction coefficient μ of the road surface) (S05). For example, if the friction coefficient μ is less than a threshold, the brake characteristic changing unit 30 selects the low μ mode.

[0032] If the vehicle speed V is not 0 (S06, No), the process proceeds to step S11.

[0033] If the vehicle speed V is 0 (S06, Yes), the brake characteristic change unit 30 notifies the driver of the brake characteristic selected in step S05 (S07). For example, information indicating the brake mode corresponding to that brake characteristic is displayed on a display on the instrument panel.

[0034] The driver determines whether a change in brake characteristics is necessary (S08), and if a change is necessary, they instruct the driver to make the change using a switch, button, or the like.

[0035] If no change in brake characteristics is instructed (S09, No), the process proceeds to step S04.

[0036] If a change in brake characteristics is instructed (S09, Yes), the brake characteristic change unit 30 changes the brake characteristics of the brake system 12 (S10). For example, if μ mode is selected, the brake characteristic change unit 30 changes the brake characteristics of the brake system 12 to μ mode.

[0037] After the brake characteristics are changed, the brake control device 22 determines whether or not a malfunction has occurred in the manual brake operating device 20 (S11). For example, a malfunction in the power supply that provides power to the manual brake operating device 20, which causes the manual brake operating device 20 to stop operating, or a malfunction in the manual brake operating device 20 due to any other reason, are examples of malfunctions in the manual brake operating device 20.

[0038] If a malfunction occurs in the manual brake control device 20 (S11, Yes), the brake control device 22 will perform the brake operation using only the brake pedal 18 without using the manual brake control device 20 (S12). In this case, even if the driver selects to perform the brake operation using the manual brake control device 20, the brake control device 22 will perform the brake operation using the brake pedal 18.

[0039] If no malfunction has occurred in the manual brake operating device 20 (S11, No), the process proceeds to step S04.

[0040] If the manual brake operating device 20 is selected by the switching operation unit 26 (S01, Yes), the brake operation is performed using the manual brake operating device 20 (S13).

[0041] When the driver starts driving (S14), the road surface information acquisition unit 28 acquires road surface information (S15) and calculates the friction coefficient μ of the road surface.

[0042] The brake characteristic changing unit 30 selects brake characteristics according to the road surface conditions (for example, the friction coefficient μ of the road surface) (S16).

[0043] If the vehicle speed V is not 0 (S17, No), the process proceeds to step S22.

[0044] If the vehicle speed V is 0 (S17, Yes), the brake characteristic changing unit 30 notifies the driver of the brake characteristic selected in step S16 (S18).

[0045] The driver determines whether a change in brake characteristics is necessary (S19), and if a change is necessary, they instruct the driver to make the change using a switch or button.

[0046] If no change in brake characteristics is instructed (S20, No), the process proceeds to step S15.

[0047] If a change in brake characteristics is instructed (S20, Yes), the brake characteristic changing unit 30 changes the brake characteristics of the brake system 12 (S21).

[0048] After the brake characteristics are changed, the brake control device 22 determines whether or not a malfunction has occurred in the manual brake operating device 20 (S22).

[0049] If a malfunction occurs in the manual brake control device 20 (S22, Yes), the switching unit 24 switches the brake operation from braking by the manual brake control device 20 to braking by the brake pedal 18 (S23). From then on, the brake control device 22 performs the brake operation using only the brake pedal 18 without using the manual brake control device 20 (S12). As a result, even if a malfunction occurs in the manual brake control device 20 while braking is being performed using the manual brake control device 20, braking force can still be applied to the vehicle by braking with the brake pedal 18.

[0050] According to this embodiment, the driver can switch between the brake pedal 18 and the manual brake operating device 20, allowing the driver to select their preferred braking method. Furthermore, the characteristics of the braking force in response to the brake operation can be changed. This improves the operability of the brake operation in achieving the target braking force compared to a case where the relationship between the amount of brake operation and the braking force is always constant.

[0051] By using an electric braking system as the braking system 12, the responsiveness of the braking force to braking operations can be improved. Furthermore, the characteristics of the braking force can be easily modified.

[0052] Since the brake system is composed of different types of EMB systems 14 and hydraulic brake systems 16, the reliability of the brake system is improved compared to when only one type of brake system is used.

[0053] In this embodiment, since the brake system 12 is configured as a drive-by-wire system, a wire harness is located inside the steering wheel, and no hydraulic piping is located there. Therefore, by using a structure that connects the wire harness to the steering wheel with a connector or the like, the steering wheel can be easily attached and detached. For example, by removing the steering wheel when getting in and out of the vehicle, a large amount of space can be secured inside the vehicle.

[0054] The brake control device 22, the switching unit 24, and the brake characteristic changing unit 30 include, for example, a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), a DSP (Digital Signal Processor), other programmable logic devices, or electronic circuits.

[0055] The functions of the brake control device 22, the switching unit 24, and the brake characteristic modification unit 30 are realized through the cooperation of hardware and software resources. For example, each function is realized when the CPU reads and executes a program stored in a storage device. The program is stored in the storage device via a recording medium such as a CD or DVD, or via a communication path such as a network. As another example, the functions of the brake control device 22, the switching unit 24, and the brake characteristic modification unit 30 may be realized by hardware resources such as electronic circuits. [Explanation of Symbols]

[0056] 10 Vehicle braking device, 12 Brake system, 14 EMB system, 16 Hydraulic brake system, 18 Brake pedal, 20 Manual brake operating device, 22 Brake operating device, 24 Switching unit, 26 Switching operation unit, 28 Road surface information acquisition unit, 30 Brake characteristic changing unit.

Claims

1. A brake pedal for applying braking force, A manual brake operating device for manually operating the brakes, A braking system that generates braking force on the vehicle in accordance with the brake operation, A means for modifying the characteristics of the braking force in response to brake operation, A switching means for switching between brake operation by the brake pedal and brake operation by the manual brake operating device, The modification means changes the amount of operation of the currently selected operating member, either the brake pedal or the manual brake operating device, relative to the target braking force, according to the driver's preference or the road surface conditions. A vehicle braking system characterized by the following:

2. In the vehicle braking device according to claim 1, The aforementioned brake system is an electric brake that generates braking force using a motor, and controls the driving force of the motor based on the target braking force. A vehicle braking system characterized by the following:

3. In the vehicle braking device according to claim 1, The brake system includes a first brake system and a second brake system. The first brake system supplies braking force directly to the friction member by a motor. The second brake system converts the motor's driving force into hydraulic pressure and supplies it to the friction member. A vehicle braking system characterized by the following:

4. A vehicle braking device according to Claim 1, The brake system, in the event of a malfunction in the manual brake operating device, disables the brake operation by the manual brake operating device and enables only the brake operation by the brake pedal. A vehicle braking system characterized by the following:

5. A vehicle braking device according to claim 2, The manual brake operating device includes a brake lever located near the steering wheel. The brake lever is connected to the brake system via a connector and a wire harness. The steering wheel is detachable from the steering column. A vehicle braking system characterized by the following:

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