JP7399553B2 - Braking control device - Google Patents

Description

The present invention relates to a brake control device for a vehicle such as a hybrid vehicle or an electric vehicle.

In vehicles such as electric cars and hybrid cars, when a motor generator is operated regeneratively, power input to a rotating shaft of the motor generator is converted into electric power, and a battery is charged with the electric power. At this time, the motor generator acts as a resistance in the drive system, and this resistance acts as a braking force (regenerative braking force) that brakes the vehicle.

The vehicle is also equipped with a hydraulic brake system. In this brake system, when the brake pedal is depressed, the force input to the brake pedal is amplified by the brake booster, and the amplified force is transmitted to the master cylinder. In the master cylinder, hydraulic pressure is generated according to the force input from the brake booster. Then, the hydraulic pressure of the master cylinder is transmitted to the brake actuator, which supplies the hydraulic pressure to the brake cylinder provided on each wheel, and presses the brake pad against the brake rotor that rotates integrally with the wheel. braking force is applied to.

A vehicle is provided with a brake switch that is turned on when the brake pedal is depressed and turned off when the brake pedal is removed. When the brake switch is turned on, power is supplied to the brake lamp, which lights up the brake lamp located at the rear of the vehicle. In addition, even if the brake pedal is not pressed, if deceleration exceeding a certain level occurs due to regenerative braking force, a lighting instruction is output from the ECU (Electronic Control Unit) to the circuit that lights the brake lamp. The brake light will turn on. By lighting the brake lamp, it is possible to notify the driver of a following vehicle that the vehicle is braking.

JP2017-74898A

However, if the brake lamp does not light up due to an abnormality such as a break in the signal line that transmits the lighting instruction from the ECU to the circuit, the driver of the following vehicle may not notice the vehicle's deceleration, and the driver of the following vehicle may may come abnormally close to.

An object of the present invention is to provide a brake control device that can prevent a following vehicle from abnormally approaching a braked vehicle when an abnormality occurs in the lighting of a brake lamp.

In order to achieve the above object, the braking control device according to the present invention is equipped with a motor generator and a brake lamp that notifies the following vehicle that it is in a braking state, and applies driving force in response to accelerator operation. A braking control device for a vehicle that applies regenerative braking force due to regenerative operation of a motor generator in response to an accelerator release operation, which issues a command to turn on a brake lamp when the deceleration of the vehicle exceeds a predetermined value. The regenerative braking force is reduced when the regenerative braking force acts on the vehicle, the deceleration of the vehicle exceeds a predetermined value, and there is an abnormality in the lighting of the brake lamp. and regeneration control means for controlling regenerative operation so that the deceleration of the vehicle is reduced to a second predetermined value or less.

According to this configuration, in a situation where regenerative braking force due to regenerative operation of the motor generator acts on the vehicle, the deceleration of the vehicle exceeds a predetermined value, and the brake lamp is turned on, an abnormality occurs in the lighting of the brake lamp. If so, the regenerative braking force will be reduced. This reduces the deceleration of the vehicle, so even if the driver of the following vehicle does not notice the vehicle's deceleration because the brake lights do not light up, the vehicle following the vehicle will abnormally approach a vehicle that is braking due to regenerative braking force. can be suppressed.

The second predetermined value may be the same value as the predetermined value, or may be a value smaller than the predetermined value. The second predetermined value may be a value larger than the predetermined value, but in that case, it is preferably set to a value that provides a deceleration that is safe and ensures the amount of regeneration, taking into consideration the current vehicle speed, etc. .

The regeneration control means has a normal regeneration mode that controls regenerative operation so that a relatively small regenerative braking force acts on the vehicle, and a strong regeneration mode that controls regenerative operation so that a relatively large regenerative braking force acts on the vehicle. It may have a mode.

In this case, the regeneration control means may prohibit the strong regeneration mode and control the regeneration operation in the normal regeneration mode in a state where an abnormality has occurred in the lighting of the brake lamp.

In addition, if a display device is installed in a position that is visible to the driver of the vehicle, the regeneration control means will indicate on the display an abnormality in the lighting of the brake lamp, a decrease in regenerative braking force, or a prohibition of strong regeneration mode. The configuration may further include display control means for controlling the display. This allows the driver to recognize this information.

According to the present invention, when an abnormality occurs in the lighting of the brake lamp, it is possible to prevent a following vehicle from abnormally approaching a vehicle in a braking state.

FIG. 1 is a block diagram showing the configuration of main parts of a vehicle equipped with a brake control device according to an embodiment of the present invention. It is a flowchart which shows the flow of processing at the time of regenerative braking.

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

<Main configuration of vehicle>
FIG. 1 is a block diagram showing the main configuration of a vehicle 1 equipped with a brake control device according to an embodiment of the present invention.

The vehicle 1 is a hybrid vehicle (HV) equipped with a motor generator (MG) 2. The power of the motor generator 2 is transmitted to the left and right drive wheels 3 via a differential gear (not shown) or the like.

The vehicle 1 is equipped with a PCU (Power Control Unit) 4 for controlling the motor generator 2 . The PCU 4 includes a built-in inverter and the like for driving the motor generator 2.

During power running of the motor generator 2, DC power output from a battery (not shown) is converted into AC power by an inverter, and the AC power is supplied to the motor generator 2 from the inverter. As a result, the motor generator 2 generates power. During regenerative operation of the motor generator 2, the motor generator 2 converts the power from the drive wheels 3 into AC power. At this time, the motor generator 2 acts as a resistance in the drive system, and regenerative braking force due to the resistance acts on the drive wheels 3. AC power generated by the motor generator 2 is converted into DC power by an inverter, and the battery is charged.

The vehicle 1 is also equipped with an ECU (Electronic Control Unit) 5 that includes a microcomputer. Although only one ECU 5 is shown in FIG. 1, the vehicle is equipped with a plurality of ECUs to control various parts. A plurality of ECUs including the ECU 5 are connected to enable bidirectional communication using a CAN (Controller Area Network) communication protocol.

Various sensors necessary for control are connected to the ECU 5. For example, an accelerator sensor 11 and a brake switch 12 are connected to the ECU 5.

The accelerator sensor 11 outputs a detection signal according to the amount of operation of the accelerator pedal 13 operated by the driver. From the detection signal of the accelerator sensor 11, the ECU 5 determines the ratio of the operation amount to the maximum operation amount of the accelerator pedal 13, that is, the time when the accelerator pedal 13 is not depressed is 0%, and the time when the accelerator pedal 13 is depressed to the maximum is determined. The accelerator opening degree, which is a percentage of 100%, can be determined.

The brake switch 12 is a switch whose contacts close and turn on when a brake pedal (not shown) operated by the driver is stepped on, and whose contacts open and turn off when the brake pedal is released. A brake signal corresponding to the on/off state of the brake switch 12 is input to the ECU 5. For example, when the brake switch 12 is on, a high-level brake signal is input to the ECU 5, and when the brake switch 12 is off, a low-level brake signal is input to the ECU 5. Therefore, the ECU 5 can determine whether the brake pedal is being operated based on the level of the brake signal.

ECU 5 controls PCU 4 and controls power running and regenerative operation of motor generator 2 based on information acquired from detection signals of various sensors, information input from other ECUs, and the like.

A brake lamp (stop lamp) 14 is arranged at the rear end of the vehicle 1. The vehicle 1 is equipped with a brake lamp circuit 15 that switches the brake lamp 14 on and off. The brake lamp circuit 15 is configured so that the brake lamp 14 is turned on when the brake switch 12 is on, and is turned off when the brake switch 12 is off. Further, the brake lamp circuit 15 is configured to turn on the brake lamp 14 in accordance with a lighting command from the ECU 5, and turn off the brake lamp 14 in accordance with a turning-off command from the ECU 5. Furthermore, the brake lamp circuit 15 is configured to be able to transmit information as to whether the brake lamp 14 is on or not to the ECU 5.

The vehicle 1 is also equipped with a display 16. The display 16 may be placed at a position that is visible to the driver, and may be, for example, a multi-information display built into a combination meter or a head-up display.

The ECU 5 controls the display on the display 16 and outputs necessary information and the like to the display 16.

<Processing during regenerative braking>
FIG. 2 is a flowchart showing the flow of processing during regenerative braking.

While the vehicle 1 is running, when the accelerator pedal 13 is released from the depressed state, that is, when the accelerator is released, the ECU 5 controls the regenerative operation of the motor generator 2 .

A normal regeneration mode and a strong regeneration mode are set as control modes for regeneration operation. In order to switch between the normal regeneration mode and the strong regeneration mode, a regeneration selector switch 17 (see FIG. 1) is provided, for example, at a position that can be operated by a driver seated in a driver's seat in the vehicle interior. Each time the regeneration selector switch 17 is pressed, a switch operation signal is input to the ECU 5, and each time the ECU 5 receives the input, the control mode of the regeneration operation is switched between the normal regeneration mode and the strong regeneration mode. In the normal regeneration mode, the regenerative operation of the motor generator 2 is controlled so that a regenerative braking force is applied to the vehicle 1 to the extent that the deceleration of the vehicle 1 does not exceed the lighting reference value of the brake lamp 14 required by the Ministry of Land, Infrastructure, Transport and Tourism. be done. On the other hand, in the strong regeneration mode, the regenerative operation of the motor generator 2 is controlled so that a large regenerative braking force exceeding the lighting reference value of the brake lamp 14 is applied to the vehicle 1.

Note that when the regeneration selector switch 17 is omitted and the accelerator opening degree is close to 0% and exceeds a predetermined value, the ECU 5 selects the normal regeneration mode. When the opening degree becomes equal to or less than a predetermined value close to 0%, the ECU 5 may select the strong regeneration mode.

During the control of the regenerative operation, the ECU 5 executes the regenerative braking process shown in FIG. 2 at a predetermined cycle.

In the regenerative braking process, first, it is determined whether the regenerative operation control mode is the strong regeneration mode (step S1). If the regenerative operation control mode is not the strong regeneration mode (NO in step S1), that is, if it is the normal regeneration mode, it is determined whether the deceleration of the vehicle 1 exceeds a predetermined value (step S2). If the deceleration of the vehicle 1 is less than or equal to the predetermined value (NO in step S2), the regenerative braking process is once terminated and executed again in the next cycle.

If the control mode for regenerative operation is the strong regeneration mode (YES in step S1), or if the deceleration of the vehicle 1 exceeds a predetermined value (YES in step S2), a command to turn on the brake lamp 14 is issued from the ECU 5. It is output to the brake lamp circuit 15 (step S3). When the brake lamp circuit 15 receives a lighting command from the ECU 5, the brake lamp 14 is turned on by the brake lamp circuit 15 in accordance with the lighting command. However, if there is a failure such as a break in the signal line that transmits commands from the ECU 5 to the brake lamp circuit 15, even if the ECU 5 outputs a command to turn on the brake lamp 14 to the brake lamp circuit 15, the lighting command will not work. Since the signal is not transmitted to the brake lamp circuit 15, the brake lamp 14 is not turned on.

Therefore, information as to whether the brake lamp 14 is lit is obtained from the brake lamp circuit 15, and it is determined whether the brake lamp 14 is lit (step S4). If the brake lamp 14 is on (YES in step S4), the regenerative braking process is once terminated and executed again in the next cycle.

On the other hand, if the brake lamp 14 is not lit even though the vehicle is in the strong regeneration mode (NO in step S4), the control mode for regenerative operation is switched from the strong regeneration mode to the normal regeneration mode (step S5). As a result, the regenerative braking force is weakened, and the deceleration of the vehicle 1 becomes such that it does not exceed the lighting reference value of the brake lamp 14. Then, in order to notify the driver that an abnormality has occurred in the lighting of the brake lamp 14, the display on the display 16 is controlled, and a warning display to the effect that the abnormality has occurred is output to the display 16. (Step S6). After that, the regenerative braking process is ended. In this case, until the vehicle 1 is taken to a maintenance factory or the like and the abnormal lighting of the brake lamp 14 is resolved, the regenerative braking process will not be executed even at the next cycle, and a warning will be output on the display 16. The display does not disappear.

Note that when switching from the strong regeneration mode to the normal regeneration mode, transient control may be performed to gradually change the regenerative braking force. Thereby, it is possible to suppress the deceleration of the vehicle 1 from suddenly changing, and it is possible to suppress giving the driver of the vehicle 1 a sense of discomfort due to the sudden change in the deceleration.

<Effect>
As described above, in the strong regeneration mode, a strong regenerative braking force is applied to the vehicle 1 due to the regenerative operation of the motor generator 2, and when the deceleration of the vehicle 1 exceeds a predetermined lighting reference value, the brake lamp 14 is turned on. situation. In this situation, if an abnormality occurs in the lighting of the brake lamp 14, the strong regeneration mode is switched to the normal regeneration mode, and the regenerative braking force is reduced. As a result, the deceleration of the vehicle 1 is reduced, so even if the driver of the following vehicle does not notice the deceleration of the vehicle 1 because the brake lamp 14 does not light up, the following vehicle is prevented from approaching the vehicle 1 abnormally. can.

When an abnormality occurs in the lighting of the brake lamp 14, switching from the normal regeneration mode to the strong regeneration mode is prohibited, and even if the regeneration selector switch 17 is pressed, the switching from the normal regeneration mode to the strong regeneration mode is prohibited. There is no switching, and control of regenerative operation in normal regeneration mode continues. This prevents the deceleration of the vehicle 1 from increasing again, and prevents the following vehicle from approaching the vehicle 1 abnormally.

Further, a warning display indicating that an abnormality has occurred in the lighting of the brake lamp 14 is output to the display 16. This allows the driver to recognize that an abnormality has occurred in the lighting of the brake lamp 14. Furthermore, if the regeneration selector switch 17 is pressed in a situation where switching from the normal regeneration mode to the strong regeneration mode is prohibited, a warning message indicating that the regeneration selector switch 17 is disabled will be displayed on the display. 16 may be output.

<Modified example>
Although one embodiment of the present invention has been described above, the present invention can also be implemented in other forms.

For example, even if the ECU 5 determines that the brake lamp 14 is abnormally lit, the driver may depress the brake pedal, the brake switch 12 is turned on, and the brake lamp 14 is accordingly turned on. In this case, even if switching from the normal regeneration mode to the strong regeneration mode is prohibited, while the brake lamp 14 is on, the normal regeneration mode is temporarily switched to the strong regeneration mode, and the motor generator 2 regenerates. Operation may be controlled. Thereby, opportunities to obtain regenerative energy through regenerative operation can be increased, and the fuel efficiency of the vehicle 1 can be improved.

The functions of the ECU 5 may be realized by cooperation of a plurality of ECUs.

Further, in the above embodiment, the vehicle 1 is a hybrid vehicle, but even if the vehicle 1 is an electric vehicle (EV), the technology of the present invention can be applied, and the above-described effects can be achieved. can play.

In addition, various design changes can be made to the above-described configuration within the scope of the claims.

1: Vehicle 2: Motor generator 5: ECU (braking control device, lighting control means, regeneration control means)
14: Brake light

Claims (3)

A motor generator , a brake pedal operated by the driver, a brake switch whose contacts close and turn on when the brake pedal is stepped on, and turn off when the contacts open, and a brake switch that informs the following vehicle that it is in a braking state. The vehicle is equipped with a brake lamp that notifies the driver , and a brake lamp circuit configured such that the brake lamp lights up when the brake switch is on and turns off when the brake switch is off, A braking control device for a vehicle in which a driving force is applied in response to an accelerator operation, and a regenerative braking force is applied by regenerative operation of the motor generator in response to an accelerator release operation,
lighting control means that outputs a command to turn on the brake lamp when the deceleration of the vehicle exceeds a predetermined value;
Based on an operation by a driver, the control mode of the regenerative operation is set to a normal regeneration mode in which the regenerative operation is controlled such that the regenerative braking force is applied to the vehicle such that the deceleration of the vehicle does not exceed the predetermined value; switching to a strong regeneration mode that controls the regenerative operation so that the regenerative braking force acts on the vehicle when the deceleration of the vehicle exceeds the predetermined value; regeneration control means for inhibiting the strong regeneration mode and controlling the regeneration operation in the normal regeneration mode when the speed exceeds the predetermined value and an abnormality occurs in the lighting of the brake lamp; Including, braking control device. The vehicle is provided with a regeneration selector switch at a position that can be operated by the driver,
The braking control device according to claim 1, wherein the regeneration control means switches the control mode of the regeneration operation between the normal regeneration mode and the strong regeneration mode based on the operation of the regeneration changeover switch. Even if the strong regeneration mode is prohibited, the regeneration control means may cause the brake lamp to turn on when the brake pedal is depressed, the brake switch is turned on, and the brake lamp is turned on. The braking control device according to claim 1 or 2 , wherein the control mode of the regenerative operation is switched from the normal regenerative mode to the strong regenerative mode during the regenerative operation.

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