JP2020049980A - Control device for vehicle - Google Patents

Abstract

To recover, as electric energy, more kinetic energy of a vehicle when urgent brake is performed.SOLUTION: A control device for a vehicle is able to perform regeneration brake in which a wheel is braked by generating power by means of a generator when a driver's foot is separated from an accelerator pedal and is able to change, during the time, the magnitude of power generated by the generator. When urgent brake not depending on the intention of the driver is performed by a brake device provided for the wheel, or at a pre-stage in which a condition for performing the urgent brake is established and the urgent brake is performed, regeneration brake by the generator is performed. In addition, the power generated by the generator in the regeneration brake is increased in comparison with power generated by the generator before the establishment of a condition for performing the urgent brake.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a control device for a vehicle capable of regenerative braking in which a generator generates power when a driver releases his / her accelerator pedal to brake a wheel.

  In recent vehicles, a collision damage mitigation brake that automatically executes braking by a brake device, that is, a drum brake or a disc brake, when the presence of an approaching preceding vehicle, a pedestrian, or another obstacle that may cause a collision is detected. (Collision avoidance assist brake) function is implemented (for example, refer to Patent Document 1 below).

  By the way, a hybrid vehicle provided with two power sources of an internal combustion engine and an electric motor has been spreading to a certain extent. A series-type hybrid vehicle (for example, see Patent Document 2 below) generates electric power by driving a motor generator for electric power generation by an internal combustion engine, stores the generated electric power in a power storage device (battery and / or capacitor), and drives the vehicle. Supply to motor generator. Then, the vehicle travels while rotating the axle and drive wheels of the vehicle by the traveling motor generator.

  In a hybrid vehicle, the vehicle can be driven by the rotational driving force output by the traveling motor generator without causing the internal combustion engine to burn fuel to generate a rotational driving force. Therefore, the state where the operation of the internal combustion engine is stopped may continue even during the operation of the vehicle.

  In the series-type hybrid vehicle, the motor generator for power generation also has a role of motoring (or cranking) the internal combustion engine when starting the stopped internal combustion engine. At the time of motoring, necessary power is supplied from the power storage device.

  The traveling motor generator also generates power by regenerative braking, and can store the generated power in the power storage device.

JP-A-2006-159758 JP-A-2006-064735

  Normally, regenerative braking is performed when the driver has released his / her foot from the accelerator pedal. The greater the power generated by regenerative braking, the greater the deceleration of the vehicle. In the known system, the driver can operate a shift lever (select lever) or a switch to switch the magnitude of the generated power during regenerative braking and the deceleration of the vehicle according to the driver's preference. Has become.

  When the power generated during the regenerative braking is set to be small, when the emergency braking is performed by the collision damage reduction brake, most of the kinetic energy of the vehicle is discarded as frictional heat by the brake device. Although the frequency of initiating emergency braking is low, loss of opportunity to recover kinetic energy as electrical energy leads to a reduction in efficiency.

  The present invention has been made in view of the above points, and an object of the present invention is to make it possible to recover more kinetic energy of a vehicle when performing emergency braking.

  According to the present invention, it is possible to perform regenerative braking for generating power by the generator and braking the wheels when the driver releases the accelerator pedal, and in this case, the magnitude of the power generated by the generator is reduced. It can be changed, when performing emergency braking without the driver's will by the brake device attached to the wheel, or at the stage before the emergency braking is executed when the condition for executing the emergency braking is satisfied, A control device for a vehicle is provided which performs regenerative braking by a generator and increases the power generated by the generator in the regenerative braking to be greater than the power generated by the generator before the condition for executing emergency braking is satisfied.

  ADVANTAGE OF THE INVENTION According to this invention, when performing emergency braking, it becomes possible to collect more kinetic energy of the vehicle as electric energy.

FIG. 1 is a diagram illustrating an outline of a series-type hybrid vehicle according to an embodiment of the present invention. The figure which shows the structure of the hydraulic circuit of the brake actuator of the vehicle in the same embodiment. The figure which shows the relationship between the vehicle speed of the vehicle at the time of regenerative braking, its deceleration, and the magnitude of the electric power generated by the generator. FIG. 4 is an exemplary flowchart showing an example of a procedure of processing executed by the vehicle control device according to the embodiment according to a program.

  An embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a schematic configuration of a main system of a hybrid vehicle according to the present embodiment. The hybrid vehicle includes an internal combustion engine 1, a power generation motor generator 2 driven by the internal combustion engine 1 to generate power, a power storage device 3 that stores power generated by the power generation motor generator 2, a power generation motor generator 2 and / or Alternatively, a driving motor generator 4 that receives supply of electric power from the power storage device 3 and drives the axle of the vehicle and the driving wheels 72 is provided.

  The hybrid vehicle of the present embodiment is a series hybrid electric vehicle that uses the internal combustion engine 1 only for power generation, and a driving wheel 72 of the vehicle is exclusively supplied with driving power for traveling from the traveling motor generator 4. The internal combustion engine 1 and the driving wheels 72 are mechanically separated from each other, and the transmission of the rotational driving force is not originally performed between them. Therefore, even if the vehicle is running when the ignition switch (power switch or ignition key) is operated to be ON, in other words, even when the driver can depress the accelerator pedal, the power storage device 3 can be operated. Does not execute the operation of the internal combustion engine 1 accompanied by the combustion of the fuel under the condition that the electric charge is stored.

  The internal combustion engine 1 is, for example, a four-stroke engine having a plurality of cylinders. The crankshaft, which is the output shaft of the internal combustion engine 1, is mechanically connected to the input shaft of the motor generator 2 for power generation. Then, by inputting the rotational driving force output from the internal combustion engine 1 to the motor generator 2 for power generation, the motor generator 2 for power generation generates power. The generated power charges the power storage device 3 and / or supplies the power to the traveling motor generator 4. Further, the motor generator 2 for power generation also functions as an electric motor that generates a rotational driving force by itself and rotationally drives the crankshaft of the internal combustion engine 1. For example, the power generating motor generator 2 may execute motoring (cranking) for starting the stopped internal combustion engine 1.

  The traveling motor generator 4 generates a driving force for traveling of the vehicle, and inputs the driving force to the driving wheels 72 via the reduction gear 71. In addition, the traveling motor generator 4 generates power by being rotated by the drive wheels 72 and rotates, and recovers kinetic energy of the vehicle as electric energy. The power generated by the regenerative braking charges the power storage device 3.

  However, when the electric charge has already been stored to the full capacity of the power storage device 3 and it is difficult to further charge the power, the generated power is dared to be supplied to the power generation motor generator 2 and the power generation motor generator 2 is connected to the electric motor. And the internal combustion engine 1 is rotationally driven. As a result, the surplus power is consumed while maintaining the braking performance of the vehicle. At this time, since the rotation of the internal combustion engine 1 is maintained, it is possible to execute a fuel cut in which the supply of fuel to the cylinders of the internal combustion engine 1 is temporarily stopped.

  Generator inverter 21 converts the AC power generated by motor generator 2 for power generation into DC power. Then, the DC power is input to power storage device 3 or driving device inverter 41. The generator inverter 21 converts the DC power supplied from the power storage device 3 and / or the drive inverter 41 into AC power when operating the power generation motor generator 2 as a motor, and then converts the power generation motor generator 2 into AC power. To enter.

  The drive inverter 41 converts DC power supplied from the power storage device 3 and / or the generator inverter 21 into AC power, and then inputs the AC power to the traveling motor generator 4. In addition, the drive inverter 41 converts AC power generated by the traveling motor generator 4 into DC power when performing regenerative braking of the vehicle, and then inputs the DC power to the power storage device 3 or the generator inverter 21.

  The generator inverter 21 and the drive inverter 41 form a part of a PCU (Power Control Unit).

  The power storage device 3 is a battery and / or a capacitor. Power storage device 3 charges and stores power generated by each of power generation motor generator 2 and traveling motor generator 4. In addition, power storage device 3 discharges electric power for operating each of power generation motor generator 2 and traveling motor generator 4 as an electric motor, and supplies necessary electric power to motor generators 2 and 4.

  The internal combustion engine 1 is provided with a brake booster (not shown) for reducing an operation force required for braking the vehicle, that is, a depression force of a brake pedal. The brake booster introduces an intake negative pressure from a portion of the intake passage of the internal combustion engine 1 downstream of the throttle valve, and boosts the depression force of a brake pedal using the negative pressure, which is widely known in the art. It is. The brake booster has a constant-pressure chamber for storing negative pressure and a variable-pressure chamber to which atmospheric pressure is applied, and the constant-pressure chamber is connected to the intake passage via a negative pressure pipe. The negative pressure line guides the intake negative pressure downstream of the throttle valve to the constant pressure chamber. A check valve is provided on the negative pressure line to keep the negative pressure in the constant pressure chamber and prevent positive pressure from being applied to the constant pressure chamber.

  When the driver does not operate the brake pedal, the constant pressure chamber and the variable pressure chamber communicate with each other, and the variable pressure chamber is isolated from the atmospheric pressure. When the brake pedal is operated, the connection between the constant pressure chamber and the variable pressure chamber is shut off, and the atmosphere is introduced into the variable pressure chamber. As a result, the pressure difference between the constant pressure chamber and the variable pressure chamber becomes a control pressure that boosts the depression force of the brake pedal. The brake depression force amplified by the brake booster is converted to a hydraulic pressure in the master cylinder. The master cylinder pressure output by the master cylinder, that is, the pressure of the brake fluid discharged from the master cylinder is transmitted to brake devices such as the brake calipers 67 and 69 and the wheel cylinders 68 and 60 via a hydraulic circuit. Used for vehicle braking by 67, 68, 69, 60.

  FIG. 2 shows a hydraulic circuit of a brake actuator of a vehicle according to the present embodiment. The master cylinder pressure is input to input lines 601 and 602 of the brake actuator. There are two input lines 601 and 602. The input line 601 of the first system is connected to brake devices 67 and 68 attached to the right front wheel and the left rear wheel of the vehicle, and supplies hydraulic pressure to the brake devices 67 and 68. The input line 602 of the second system is connected to brake devices 69, 60 attached to the left front wheel and the right rear wheel of the vehicle, and supplies hydraulic pressure to the brake devices 69, 60.

  The brake devices 67, 68, 69, 60 are, for example, brake calipers 67, 69 for generating a braking force by pressing pads on both surfaces of a disk that rotates together with wheels in a disk brake, or rotating together with wheels in a drum brake. Wheel cylinders 68 and 60 for generating a braking force by pressing the shoe against the inner surface of the drum to be driven.

  Master cylinder cut solenoid valves 61 and 62 are arranged on a hydraulic circuit that connects the input lines 601 and 602 of each system and the brake devices 67, 68, 69 and 60. By closing the first master cylinder cut solenoid valve 61 present on the circuit of the first system, the right front wheel brake caliper 67 and the left rear wheel cylinder 68, which are brake devices connected to the first system, are closed. It plays a role in maintaining the supplied liquid pressure. By closing the second master cylinder cut solenoid valve 62 present on the circuit of the second system, the left front wheel brake caliper 69 and the right rear wheel cylinder 60, which are the brake devices connected to the second system, are closed. It plays a role in maintaining the supplied liquid pressure.

  In addition, a holding solenoid valve 63 and a pressure reducing solenoid valve 64 for configuring an ABS (Antilock Break System) are also arranged on the hydraulic circuit. By combining the opening / closing of these valves 63, 64, the hydraulic pressure supplied to each of the brake devices 67, 68, 69, 60 is adjusted, and the braking force exerted by the brake devices 67, 68, 69, 60 is increased. It is possible to increase or decrease the length. Normally, the pressure is increased by opening the holding solenoid valve 63 and closing the pressure reducing solenoid valve 64. However, the pressure can be reduced by closing the holding solenoid valve 63 and opening the pressure reducing solenoid valve 64. The reservoir 65 temporarily stores the brake fluid flowing from the brake devices 67, 68, 69, 60 when the pressure is reduced. The electric pump 66 sucks, discharges, pumps, and recirculates the brake fluid stored in the reservoir 65. If both the holding solenoid valve 63 and the pressure reducing solenoid valve 64 are closed, the liquid pressure supplied to each of the brake devices 67, 68, 69, 60 can be held.

  An ECU (Electronic Control Unit) 0 that is a control device that controls the internal combustion engine 1, the power generation motor generator 2, the power storage device 3, the inverters 21 and 41, the traveling motor generator 4, and the brake devices 67, 68, 69, and 60 includes: This is a microcomputer system having a processor, a memory, an input interface, an output interface, and the like. The ECU 0 includes a plurality of ECUs (for example, controllers that individually control the internal combustion engine 1, the motor generators 2 and 4, the power storage device 3, and the brake devices 67, 68, 69, and 60). May be communicably connected to each other via a telecommunication line.

  The ECU 0 responds to the accelerator pedal depression amount by the driver who is sensing via the sensor, the current vehicle speed of the vehicle, the gradient of the road surface, the amount of power stored in the power storage device 3, the power generated by the motor generator 2 for power generation, and the like. In addition, it controls the rotational driving force output by the traveling motor generator 4, the rotational driving force output by the internal combustion engine 1, and the power generated by the power generating motor generator 2 to increase or decrease. If the power storage device 3 is currently storing a sufficient charge and the output driving force required for the traveling motor generator 4 is not at a maximum, the supply of fuel to the internal combustion engine 1 is shut off and the internal combustion engine 1 is not operated. .

  In contrast, when the amount of electric charge currently stored in power storage device 3 is less than a predetermined amount, or when the output driving force required for traveling motor generator 4 is maximum, internal combustion engine 1 is started. At the same time, fuel is supplied to the internal combustion engine 1 to burn the fuel, and the power generation motor generator 2 is driven by the rotational driving force output from the internal combustion engine 1 to perform power generation to charge the power storage device 3 or 4 is increased.

  While the internal combustion engine 1 is not operating by supplying fuel to the cylinders of the internal combustion engine 1, the internal combustion engine 1 is started while the driving wheels 72 are driven by the traveling motor generator 4 to drive the vehicle. Then, the motor generator 2 for power generation performs motoring for starting the internal combustion engine 1.

  The motoring for starting the internal combustion engine 1 continues until the internal combustion engine 1 can burn fuel and rotate independently. More specifically, the rotational speed of the crankshaft of the internal combustion engine 1 which is being sensed is increased to a minimum threshold value required for starting or more, and the crankshaft of the internal combustion engine 1 is rotated for a predetermined number of times or a predetermined time from the start of motoring. When the motor rotates by the angle or more, the motoring ends. The condition that the crankshaft has rotated a predetermined number of times or more than a predetermined angle may be replaced with a condition that the cylinder determination for obtaining the current stroke or the position of the piston of each cylinder of the internal combustion engine 1 has been completed. In order to inject fuel at an appropriate timing according to the stroke of each cylinder and to ignite and burn the fuel at an appropriate timing, it is necessary to know the current stroke of each cylinder. Cylinder discrimination is based on a crank angle sensor that emits a pulse signal each time the crankshaft rotates a predetermined angle (for example, 10 ° CA), and an intake camshaft or exhaust camshaft that divides one rotation of the camshaft by the number of cylinders. Angle: In the case of a three-cylinder engine, this is performed using a cam angle sensor that emits a pulse signal each time it rotates 120 ° (240 ° CA). Since the cylinder discriminating method is well known, its description is omitted here. However, in order to complete the cylinder discrimination with reference to the crank angle signal and the cam angle signal, the stopped crankshaft of the internal combustion engine 1 must It is necessary to rotate about the rotation. The length of time required from the start to the end of motoring is a few seconds or less as long as the power storage device 3 has not failed.

  After the start of the internal combustion engine 1 is completed and the motoring of the internal combustion engine 1 is ended, the power supply to the motor generator 2 for power generation is reduced to zero.

  When the driver of the vehicle releases the foot from the accelerator pedal or attempts to perform regenerative braking in response to depressing the brake pedal, the power (or voltage) generated by the traveling motor generator 4 operating as a generator Or the magnitude of the current) can be changed. FIG. 3 shows the relationship between the vehicle speed and the deceleration of the vehicle during regenerative braking and the amount of power generated by the motor generator 4 for traveling. In FIG. 3, the solid line represents the mode in which the generated power is the smallest, the broken line represents the mode in which the generated power is medium, and the dashed line represents the mode in which the generated power is the largest. As in the illustrated example, the larger the power generated by the traveling motor generator 4 during regenerative braking, the greater the deceleration of the vehicle. Incidentally, the two-dot chain line in FIG. 3 indicates the deceleration of the vehicle when the emergency braking using the brake devices 67, 68, 69, and 60 is performed together.

  The driver can select one of the above modes by operating a shift lever (select lever) or a switch, for example. The ECU 0 of the present embodiment obtains the mode selected by the driver via the shift lever or the like, and controls the magnitude of the generated power of the traveling motor generator 4 during regenerative braking so as to match the mode. . Thereby, the deceleration of the vehicle that matches the driver's preference can be realized.

  The vehicle according to the present embodiment does not depend on the driver's intention, that is, depressing the brake pedal operated by the driver when detecting the presence of an approaching preceding vehicle, a pedestrian, or another obstacle that may cause a collision. Equipped with a collision damage reduction brake (collision avoidance support brake) function that automatically performs emergency braking regardless of the amount.

  The ECU 0 of the present embodiment detects the presence of a preceding vehicle, a pedestrian, and other obstacles via devices such as a stereo camera, a laser radar, a millimeter wave radar, and an ultrasonic sonar. Then, as shown in FIG. 4, when the execution condition of the emergency braking that the vehicle speed is higher than a predetermined value and the distance between the vehicle and the obstacle approaches a predetermined range is satisfied (step S1), the driving is performed. The regenerative braking that controls the magnitude of the generated power of the traveling motor generator 4 is automatically performed in accordance with the mode in which the generated power is the largest, ignoring the mode currently selected by the user (step S2). Emergency braking is performed by the brake devices 67, 68, 69, 60 (step S3). At this time, the magnitude of the braking force exerted by the brake devices 67, 68, 69, 60 (in other words, the magnitude of the hydraulic fluid supplied to the brake devices 67, 68, 69, 60) is increased by the regenerative braking. The greater the braking force exerted by the driving motor generator 4 (in other words, the larger the generated power of the traveling motor generator 4), the more the braking force can be reduced.

  When the distance between the vehicle and the obstacle approaches a predetermined range, a warning is first issued as a precedent to emergency braking in a manner appealing to the driver's sight or hearing (sounding a buzzer, turning on or flashing a lamp). Then, when the distance between the vehicle and the obstacle is further reduced, emergency braking by the brake devices 67, 68, 69, 60 can be performed. In this case, at the stage of issuing the warning, the regenerative braking for controlling the magnitude of the generated power of the traveling motor generator 4 is started in accordance with the mode in which the generated power is the largest (at this time, the braking devices 67 and 68 are still being provided). , 69 and 60 are not started).

  In the present embodiment, when the driver has released his / her foot from the accelerator pedal, it is possible to perform regenerative braking in which the power is generated by the generator 4 and the wheels 72 are braked. Can be changed, and when the brake devices 67, 68, 69, and 60 attached to the wheels 72 execute emergency braking without the driver's intention, or conditions for executing emergency braking are satisfied. Before the emergency braking is performed, the regenerative braking by the generator 4 is performed, and the power generated by the generator 4 in the regenerative braking is generated by the generator 4 before the condition for performing the emergency braking is satisfied. The control device 0 of the vehicle for increasing the electric power is configured.

  According to the present embodiment, more kinetic energy of the vehicle can be recovered as electric energy in the power storage device 3 when emergency braking is performed, which can contribute to further improvement in efficiency.

  Note that the present invention is not limited to the embodiment described in detail above. In particular, the application of the present invention is not limited to a series-type hybrid vehicle as long as it is a vehicle that can perform regenerative braking in which wheels are braked by generating power using a generator.

  In addition, the specific configuration of each unit and the content of processing can be variously modified without departing from the spirit of the present invention.

  INDUSTRIAL APPLICABILITY The present invention can be applied to control of a vehicle equipped with an electric motor for performing regenerative braking.

0 ... Control device (ECU)
DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine 3 ... Power storage device 4 ... Generator (motor generator for driving | running | working)
67, 68, 69, 60 ... brake device

Claims (1)

When the driver has released his / her foot from the accelerator pedal, it is possible to perform regenerative braking to generate power by the generator and brake the wheels, and to change the amount of power generated by the generator at that time. So,
When performing emergency braking not depending on the driver's intention by the brake device attached to the wheel, or at a stage where the condition for executing the emergency braking is satisfied and before performing the emergency braking, perform regenerative braking by the generator, and A control device for a vehicle, wherein the power generated by the generator in the regenerative braking is increased more than the power generated by the generator before the condition for executing the emergency braking is satisfied.

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