Brake control device

Abstract

To provide a brake control device which can decelerates an automobile earlier by a regeneration brake.SOLUTION: In a brake control device 1 of an automobile 100 which drives drive wheels 105 by an electric motor 103 to which electric power is supplied from a battery 102 and achieves brake force by a regeneration brake of the electric motor 103 while charging the battery 102, it can decelerate the automobile 100 earlier by the regeneration brake because rotational frequency of the electric motor 103 is increased with respect to rotational frequency of the drive wheels 105 by transmission processing part 22 when the regeneration brake is operated.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] There has been proposed a vehicle in which the drive wheels are driven by an electric motor supplied with power from a battery, and braking force is obtained by regenerative braking of the electric motor while charging the battery. For example, Patent Document 1 discloses a device that activates regenerative braking when braking force cannot be obtained by the service brakes of the vehicle. In the device of Patent Document 1, when the regenerative braking is activated, surplus power that cannot be charged to the battery is supplied to a load, converted into thermal energy, and consumed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-207926 Summary of the Invention [Problem to be solved by the invention]

[0004] However, with the above-mentioned technology, there is a demand for a technology that can decelerate the vehicle more quickly by using regenerative braking when it is not possible to obtain braking force from the service brakes.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a brake control device that can decelerate an automobile more quickly by using regenerative braking. [Means for solving the problem]

[0006] The present invention is a brake control device for an automobile in which the drive wheels are driven by an electric motor supplied with power from a battery, and braking force is obtained by regenerative braking of the electric motor while charging the battery.The brake control device is equipped with a gear change processing unit that increases the rotation speed of the electric motor relative to the rotation speed of the drive wheels when the regenerative braking is activated.

[0007] According to this configuration, in a brake control device for an automobile in which the drive wheels are driven by an electric motor supplied with power from a battery, and braking force is obtained by regenerative braking of the electric motor while charging the battery, the shift processing unit increases the rotation speed of the electric motor relative to the rotation speed of the drive wheels when the regenerative braking is activated, so that the automobile can be decelerated more quickly by the regenerative braking.

[0008] In this case, it is preferable to further include an overcharge prevention unit that supplies surplus power that cannot be charged into the battery to a load when regenerative braking is activated.

[0009] According to this configuration, the overcharge prevention unit supplies the excess power that cannot be charged into the battery to the load when regenerative braking is activated, thereby preventing the battery from being overcharged.

[0010] It is also preferable that the vehicle further comprises an emergency brake operating unit that operates a regenerative brake when braking force cannot be obtained by the service brakes of the vehicle.

[0011] According to this configuration, the emergency brake operating unit operates the regenerative brake when braking force cannot be obtained from the vehicle's service brakes, so that braking force can be obtained even when the service brakes fail.

[0012] It is also preferable to further include a deceleration control unit that maintains the deceleration of the vehicle at or below a threshold value when regenerative braking is activated.

[0013] According to this configuration, the deceleration control unit maintains the deceleration of the vehicle at or below the threshold value when regenerative braking is activated, thereby reducing the impact on vehicle occupants. [Effects of the Invention]

[0014] According to the brake control device of the present invention, the vehicle can be decelerated more quickly by regenerative braking. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a block diagram showing a brake control device according to an embodiment; [Figure 2] 3 is a flowchart illustrating the operation of the brake control device according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0016] A brake control device according to an embodiment of the present invention will be described in detail below with reference to the drawings. The brake control device 1 shown in Fig. 1 is mounted on an automobile 100 and controls the brakes of the automobile 100. The automobile 100 drives drive wheels 105 with an electric motor 103 supplied with power from an FC stack 101 and a battery 102, and obtains braking force through regenerative braking of the electric motor 103 while charging the battery 102.

[0017] In Fig. 1, connections between components indicated by thin lines represent connections via communication circuits such as a CAN (Controller Area Network). In Fig. 1, connections between components indicated by double lines represent connections via electrical circuits. In Fig. 1, connections between components indicated by thick lines represent connections via power transmission mechanisms such as power shafts.

[0018] The automobile 100 includes an FC stack 101, a battery 102, an electric motor 103, a transmission 104, and drive wheels 105. The FC (fuel cell) stack 101 is a stack of multiple fuel cell cells that generate electricity by reacting hydrogen with oxygen in the air, and supplies power to the electric motor 103. The transmission 104 is a mechanical device that changes the rotation speed of the drive wheels 105 relative to the rotation speed of the electric motor 103, and the rotation speed of the electric motor 103 relative to the rotation speed of the drive wheels 105. The transmission 104 may be a continuously variable transmission.

[0019] The brake control device 1 includes an FC-ECU 10, an EV-ECU 20, an INV-ECU 30, a service brake torque detection unit 40, and a brake register 50. The FC-ECU 10, the EV-ECU 20, and the INV-ECU 30 are electronic control units (ECUs) that include a central processing unit (CPU), read-only memory (ROM), random access memory (RAM), and a hard disk drive (HDD). The FC (fuel cell)-ECU 10 controls the operation of an FC stack 101.

[0020] The EV (Electronic Vehicle)-ECU 20 controls the running and braking of the automobile 100. The EV-ECU 20 has an emergency brake actuation unit 21, a gear shift processing unit 22, an overcharge prevention unit 23, and a deceleration control unit 24. The EV-ECU 20 loads a program stored in a ROM into a RAM and executes it on a CPU, thereby controlling each unit such as the emergency brake actuation unit 21. The EV-ECU 20 may be composed of multiple electronic control units.

[0021] The emergency brake actuation unit 21 activates the regenerative brake when braking force cannot be obtained from the service brake of the automobile 100. The depression amount of the brake pedal of the automobile 100 and the braking force (brake torque) from the service brake of the automobile 100 are detected by the service brake torque detection unit 40. When the service brake torque detection unit 40 detects that the brake pedal of the automobile 100 is depressed but does not detect brake torque from the service brake, the emergency brake actuation unit 21 cooperates with the shift processing unit 22, the overcharge prevention unit 23, and the deceleration control unit 24 to activate the regenerative brake.

[0022] In addition, the emergency brake activation unit 21 may activate the regenerative brake when the deceleration of the automobile 100 is not detected by the acceleration sensor even though it is detected that the brake pedal of the automobile 100 is being depressed.

[0023] When regenerative braking is activated, the gear shift processing unit 22 increases the rotation speed (reduction ratio) of the electric motor 103 relative to the rotation speed of the drive wheels 105 by sending a command signal to the transmission 104.

[0024] The overcharge prevention unit 23 supplies excess power that cannot be charged to the battery 102 to a brake resistor (load) 50 during regenerative braking. The overcharge prevention unit 23 acquires the state of charge (SOC) of the battery 102 from the temperature of the battery 102, the voltage of the battery 102, and an integrated value of the current flowing in and out of the battery 102, etc. The brake resistor 50 is an electric resistor that converts excess power that cannot be charged to the battery 102 into thermal energy and consumes it. Note that the brake resistor 50 may be another type of electric load that can consume excess power that cannot be charged to the battery 102.

[0025] When the regenerative brake is activated, the deceleration control unit 24 controls the braking force (brake torque) of the regenerative brake by sending a command signal to the INV-ECU 30 and the transmission 104, thereby maintaining the deceleration of the automobile 100 at or below a threshold. The INV-ECU 30 controls an inverter (not shown) that converts the power supplied from the FC stack 101 and the battery 102 to the electric motor 103 and the power supplied from the electric motor 103 to the battery 102 and the brake resistor 50. The deceleration threshold is set to a value of, for example, about 0.1 to 0.3 G depending on the amount of depression of the brake pedal.

[0026] The operation of the brake control device 1 of this embodiment will be described below. In the following description, it is assumed that the automobile 100 is traveling. As shown in Fig. 2, the brake pedal of the automobile 100 is depressed, and the service brake of the automobile 100 is turned on (S1). The service brake torque detection unit 40 detects the depression amount of the brake pedal of the automobile 100 and the brake torque due to the service brake of the automobile 100 (S2).

[0027] When the service brake torque detection unit 40 detects that the brake pedal of the automobile 100 has been depressed but does not detect the brake torque due to the service brake, that is, when braking force cannot be obtained by the service brake of the automobile (S3), the emergency brake activation unit 21 activates the regenerative brake (S4).

[0028] When regenerative braking is activated, the gear shift processing unit 22 determines (S5) using a vehicle speed sensor (not shown) whether the vehicle speed of the automobile 100 allows for gear shifting by the transmission 104. This determination is made to prevent damage to the gears of the electric motor 103 in the event of gear shifting at a vehicle speed at which gear shifting is not possible.

[0029] If the vehicle speed is within the range where gear shifting is possible (S5), the gear shift processing unit 22 increases the rotation speed of the electric motor 103 relative to the rotation speed of the drive wheels 105 during regenerative braking by sending a command signal to the transmission 104 (S6). The deceleration control unit 24 calculates (the threshold value of) the deceleration of the vehicle 100 based on the amount of depression of the brake pedal detected by the service brake torque detection unit 40 (S7). The deceleration control unit 24 controls the brake torque of the regenerative brake by sending a command signal to the INV-ECU 30 and the transmission 104, and maintains the deceleration of the vehicle 100 at or below the threshold (S8).

[0030] When the acquired charge status of the battery 102 is close to full charge and there is surplus power that cannot be charged to the battery 102 (S9), the overcharge prevention unit 23 supplies the surplus power that cannot be charged to the battery 102 to the brake resistor 50 (S10).

[0031] On the other hand, if the vehicle speed is at a speed at which shifting is not possible (S5), steps S11 to S14 are executed (S5) similar to steps S7 to S10 above, without increasing the rotation speed of electric motor 103 relative to the rotation speed of drive wheels 105. If the vehicle speed becomes a speed at which shifting is possible (S5), steps S7 to S10 above are executed.

[0032] According to this embodiment, in the brake control device 1 of the automobile 100, in which the drive wheels 105 are driven by the electric motor 103 supplied with power from the battery 102, and braking force is obtained by the regenerative braking of the electric motor 103 while charging the battery 102, the shift processing unit 22 increases the rotation speed of the electric motor 103 relative to the rotation speed of the drive wheels 105 when the regenerative braking is activated, so that the automobile 100 can be decelerated more quickly by the regenerative braking.

[0033] Furthermore, according to this embodiment, the overcharge prevention unit 23 supplies the excess power that cannot be charged into the battery 102 to the brake resistor 50 during regenerative braking, thereby preventing the battery 102 from being overcharged.

[0034] Furthermore, according to this embodiment, the emergency brake operating unit 21 operates the regenerative brake when braking force cannot be obtained from the service brake of the automobile 100, so that braking force can be obtained even when the service brake fails.

[0035] Furthermore, according to this embodiment, the deceleration control unit 24 maintains the deceleration of the automobile 100 at or below a threshold value when regenerative braking is activated, thereby reducing the impact on passengers of the automobile 100.

[0036] Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments and can be embodied in various forms. [Explanation of symbols]

[0037] 1...Brake control device, 10...FC-ECU, 20...EV-ECU, 21...Emergency brake activation unit, 22...Speed ​​change processing unit, 23...Overcharge prevention unit, 24...Deceleration control unit, 30...INV-ECU, 40...Service brake torque detection unit, 50...Brake resistor (load), 100...Automobile, 101...FC stack, 102...Battery, 103...Electric motor, 104...Transmission, 105...Drive wheels

Claims

1. A brake control device for an automobile in which drive wheels are driven by an electric motor supplied with power from a battery, and braking force is obtained by regenerative braking of the electric motor while charging the battery, A brake control device equipped with a gear shift processing unit that, when the regenerative brake is activated, determines whether the vehicle speed of the vehicle is at a speed at which gear shifting by the transmission is possible, and if it is determined that the vehicle speed of the vehicle is at a speed at which gear shifting by the transmission is possible, increases the rotation speed of the electric motor relative to the rotation speed of the drive wheels, and if it is determined that the vehicle speed of the vehicle is at a speed at which gear shifting by the transmission is not possible, does not increase the rotation speed of the electric motor relative to the rotation speed of the drive wheels.

2. The brake control device according to claim 1, further comprising an overcharge prevention unit that supplies surplus power that cannot be charged to the battery to a load when the regenerative brake is activated.

3. 3. The brake control device according to claim 1, further comprising an emergency brake actuation unit that activates the regenerative brake when braking force cannot be obtained by a service brake of the vehicle.

4. 4. The brake control device according to claim 1, further comprising a deceleration control unit that maintains the deceleration of the vehicle at or below a threshold value when the regenerative brake is activated.

Images