JP7175563B2 - vehicle controller - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for a vehicle capable of regenerative braking, in which power is generated by a generator to brake the wheels when the driver takes his/her foot off the accelerator pedal.

In recent years, hybrid vehicles equipped with two power sources, an internal combustion engine and an electric motor, are gaining popularity. A series-type hybrid vehicle (see, for example, the following patent document) generates power by driving a motor generator for power generation with an internal combustion engine, stores the generated power in a power storage device (battery and/or capacitor), and drives a motor. feed the generator. Then, the motor generator for traveling rotates the axle of the vehicle, and thus the drive wheels, to travel.

In a hybrid vehicle, even if the internal combustion engine does not burn fuel to generate rotational driving force, the vehicle can be driven by the rotational driving force output from the motor generator for traveling. Therefore, even during operation of the vehicle, the state where the operation of the internal combustion engine is stopped may continue.

In a series-system hybrid vehicle, the motor generator for power generation also serves to motor (or crank) the internal combustion engine when starting the stopped internal combustion engine. During motoring, the required power is supplied from the power storage device.

Furthermore, the motor-generator for running can also generate electric power by regenerative braking, and the generated electric power can be stored in the power storage device.

JP 2016-064735 A

Regenerative braking is normally performed when the driver takes his/her foot off 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 manually switch the magnitude of the generated power during regenerative braking and the deceleration of the vehicle according to the driver's preference by operating a shift lever (select lever) or switch. It is possible.

On the other hand, when the driver depresses the brake pedal, it is of course possible to perform braking using a friction brake device attached to the wheels, such as a foot brake, ie, a disc brake or a drum brake. This type of brake device drives the brake calipers and wheel cylinders by hydraulic pressure.

In a hydraulic brake system, the brake fluid, which is the working fluid, may be overheated and boiled by frictional heat in the brake caliper or wheel cylinder, and steam bubbles may be generated in the hydraulic circuit. If this phenomenon becomes conspicuous, even if the driver steps on the brake pedal, sufficient hydraulic pressure cannot be applied to the brake caliper or wheel cylinder, and the braking performance of the brake system deteriorates. This phenomenon, called vapor lock, can occur due to extensive use of the braking system, such as on long downhill slopes.

SUMMARY OF THE INVENTION It is an object of the present invention to realize a fail-safe system that can safely decelerate or stop a vehicle even when an event occurs that makes normal braking difficult in the brake system.

In the present invention, when the driver takes his/her foot off the accelerator pedal, it is possible to perform regenerative braking in which power is generated by the generator to brake the wheels. It can be changed based on the current brake pedal depression amount or master cylinder pressure and the hydraulic pressure applied to the brake device attached to the wheel, or the current brake pedal depression amount or master cylinder pressure Based on the deceleration of the vehicle speed and the deceleration of the vehicle speed, it is determined whether or not a vapor lock has occurred that makes normal braking difficult in the brake device, and if it is determined that a vapor lock has occurred, the regenerative braking generated by the generator automatically shifts to a one-pedal operation mode in which acceleration, deceleration and braking can be performed by operating only the accelerator pedal, The braking force exerted by the generator is increased to such an extent that the vehicle can almost or completely stop when the driver releases the accelerator pedal and the amount of depression of the accelerator pedal becomes 0 or a minimal value close to 0 . Constructed the controller.

ADVANTAGE OF THE INVENTION According to this invention, the fail safe which can decelerate or stop a vehicle safely is implement|achieved, even when the event which makes normal braking difficult occurs in a brake device.

1 is a diagram showing an outline of a series-type hybrid vehicle in one embodiment of the present invention; FIG. The figure which shows the structure of the hydraulic circuit of the brake actuator of the vehicle in the same embodiment. FIG. 4 is a diagram showing the relationship between the vehicle speed and deceleration of the vehicle during regenerative braking and the power generated by the generator; FIG. 2 is a flowchart showing an example of the procedure of processing executed by the vehicle control device according to the embodiment according to the program;

One embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a schematic configuration of main systems of a hybrid vehicle in this embodiment. This hybrid vehicle includes an internal combustion engine 1, a power generating motor generator 2 that is driven by the internal combustion engine 1 to generate power, a power storage device 3 that stores the electric power generated by the power generating motor generator 2, the power generating motor generator 2 and/or Alternatively, a motor-generator 4 for traveling is provided that receives power supply from the power storage device 3 to drive the axles and drive wheels 72 of the vehicle.

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 the drive wheels 72 of the vehicle are exclusively supplied with driving force for running from the motor generator 4 for running. The internal combustion engine 1 and the drive wheels 72 are mechanically separated from each other, and originally rotational driving force is not transmitted between them. Therefore, during operation of the vehicle with the ignition switch (power switch or ignition key) turned on, in other words, even when the vehicle is in a state in which the vehicle can travel by depressing the accelerator pedal, the power storage device 3 is sufficiently charged, the operation of the internal combustion engine 1 involving combustion of fuel is not performed.

The internal combustion engine 1 is, for example, a four-stroke engine containing multiple cylinders. A crankshaft, which is an output shaft of the internal combustion engine 1, is mechanically connected to an input shaft of a motor generator 2 for power generation. By inputting the rotational driving force output by the internal combustion engine 1 to the electric power generating motor generator 2, the electric power generating motor generator 2 generates electric power. The generated electric power is charged in the power storage device 3 and/or supplied to the traveling motor generator 4 . In addition, the electric power generation motor generator 2 also functions as an electric motor that generates rotational driving force by itself to rotationally drive the crankshaft of the internal combustion engine 1 . For example, the power generation motor generator 2 may perform motoring (cranking) to start the stopped internal combustion engine 1 .

The running motor generator 4 generates a driving force for running the vehicle, and inputs the driving force to the driving wheels 72 via the speed reducer 71 . In addition, the running motor generator 4 rotates together with the driving wheels 72 to generate electric power, and recovers the kinetic energy of the vehicle as electric energy. The electric power generated by this regenerative braking charges the power storage device 3 .

However, if electric charge is already stored up to the capacity of the power storage device 3 and further charging is difficult, the generated electric power is intentionally supplied to the electric power generation motor generator 2, and the electric power generation motor generator 2 is turned to the electric motor. to rotate the internal combustion engine 1. This consumes excess electric power while maintaining the braking performance of the vehicle. Further, at this time, since the rotation of the internal combustion engine 1 is maintained, fuel cut can be executed to temporarily stop the supply of fuel to the cylinders of the internal combustion engine 1 .

The power generator inverter 21 converts the AC power generated by the power generation motor generator 2 into DC power. Then, the DC power is input to power storage device 3 or drive inverter 41 . In addition, when the power generation motor generator 2 is operated as an electric motor, the power generator inverter 21 converts the DC power supplied from the power storage device 3 and/or the drive inverter 41 into AC power, and then converts the power generation motor generator 2 into AC power. to enter.

The drive inverter 41 converts the DC power supplied from the power storage device 3 and/or the generator inverter 21 into AC power and inputs the AC power to the motor generator 4 for running. In addition, the drive inverter 41 converts AC power generated by the traveling motor generator 4 when the vehicle is regeneratively braked into DC power and 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 part of a PCU (Power Control Unit).

The power storage device 3 is a battery and/or a capacitor or the like. The power storage device 3 charges and stores electric power generated by each of the motor generator 2 for power generation and the motor generator 4 for running. Power storage device 3 also discharges electric power for operating motor generator 2 for electric power generation and motor generator 4 for running as electric motors, 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 the operating force required for braking the vehicle, that is, the force applied to the brake pedal. A brake booster introduces intake negative pressure from a portion downstream of a throttle valve in the intake passage of the internal combustion engine 1, and uses the negative pressure to boost the depression force of the brake pedal, which is widely known in this field. is. The brake booster has a constant pressure chamber that stores negative pressure and a variable pressure chamber to which atmospheric pressure is applied. The constant pressure chamber is connected to an intake passage via a negative pressure line. The negative pressure line guides the intake negative pressure on the downstream side of the throttle valve to the constant pressure chamber. A check valve is provided on the negative pressure line to retain 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 communicates with the variable pressure chamber, and the variable pressure chamber is isolated from the atmospheric pressure. When the brake pedal is operated, the constant pressure chamber and the variable pressure chamber are cut off, and air is introduced into the variable pressure chamber. As a result, the pressure difference between the constant pressure chamber and the variable pressure chamber becomes the control pressure that boosts the force applied to the brake pedal. The brake depression force amplified by the brake booster is converted into hydraulic pressure in the master cylinder. The master cylinder pressure output by the master cylinder, that is, the pressure of the brake fluid discharged by the master cylinder is transmitted to brake devices such as brake calipers 67 and 69 and wheel cylinders 68 and 60 through hydraulic circuits. 67, 68, 69, 60 are used to brake the vehicle.

FIG. 2 shows the hydraulic circuit of the vehicle brake actuator in this embodiment. Master cylinder pressure is input to input lines 601, 602 of the brake actuator. There are two systems of input lines 601 and 602 . The input line 601 of the first system is connected to brake devices 67, 68 associated with the right front wheel and the left rear wheel of the vehicle, and supplies hydraulic pressure to these brake devices 67, 68. The input line 602 of the second system is connected to brake devices 69, 60 associated with the left front wheel and the right rear wheel of the vehicle, and supplies hydraulic pressure to these brake devices 69, 60.

The brake devices 67, 68, 69, 60 are, for example, brake calipers 67, 69 for generating braking force by pressing pads against both sides of a disk that rotates with the wheel in a disk brake, or a drum brake that rotates with the wheel. Wheel cylinders 68 and 60 for generating braking force by pressing shoes against the inner surface of the drum.

Master cylinder cut solenoid valves 61 and 62 are arranged on hydraulic circuits connecting input lines 601 and 602 of each system and brake devices 67, 68, 69 and 60, respectively. When the first master cylinder cut solenoid valve 61 existing on the circuit of the first system is closed, the right front wheel brake caliper 67 and the left rear wheel cylinder 68, which are brake devices connected to the same system, are cut. It plays the role of maintaining the supplied hydraulic pressure. The second master cylinder cut solenoid valve 62, which exists on the circuit of the second system, is closed to cut off the left front wheel brake caliper 69 and the right rear wheel cylinder 60, which are the brake devices connected to the same system. It plays the role of maintaining the supplied hydraulic pressure.

In addition, a holding solenoid valve 63 and a pressure reducing solenoid valve 64 for constructing an ABS (Antilock Brake System) are also arranged on the hydraulic circuit. By combining the opening/closing of these valves 63, 64, the hydraulic pressure supplied to each brake device 67, 68, 69, 60 is adjusted, and the braking force exerted by the brake device 67, 68, 69, 60 is increased. can be increased or decreased. Normally, the pressure is increased by opening the holding solenoid valve 63 and closing the pressure reducing solenoid valve 64 , but 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 the brake fluid stored in the reservoir 65, discharges it, pumps it, and circulates it. By closing both the holding solenoid valve 63 and the pressure reducing solenoid valve 64, the hydraulic pressure supplied to each brake device 67, 68, 69, 60 can be held.

An ECU (Electronic Control Unit) 0, which is a control device for controlling the internal combustion engine 1, the power generation motor generator 2, the power storage device 3, the inverters 21 and 41, the running motor generator 4, and the brake devices 67, 68, 69, and 60, It is a microcomputer system having a processor, memory, input interface, 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, 60, etc.) are connected to a CAN (Controller Area Network) or the like. may be connected so as to be able to communicate with each other via an electric communication line.

The ECU 0 senses the amount of depression of the accelerator pedal by the driver via sensors, the current vehicle speed, the slope of the road surface, the amount of electricity stored in the electricity storage device 3, the power generated by the power generation motor generator 2, and the like. , increase/decrease control of the rotational driving force output by the traveling motor generator 4, the rotational driving force output by the internal combustion engine 1, and the magnitude of the electric power generated by the power generating motor generator 2. If the power storage device 3 is currently storing a sufficient amount of electric charge and the output driving force required of the motor generator 4 for traveling is not maximum, the supply of fuel to the internal combustion engine 1 is cut off and the internal combustion engine 1 is not operated. .

When the amount of electric charge currently stored in power storage device 3 is below a predetermined amount, or when the output drive force required of motor generator 4 for traveling is maximum, internal combustion engine 1 is started and internal combustion engine 1 is supplied with fuel to burn it, and the rotational driving force output from the internal combustion engine 1 is used to drive a power generation amount motor generator 2, which generates power to charge a power storage device 3 or is supplied to a travel motor generator 4. increase the power to run.

Let's try to start the internal combustion engine 1 while the vehicle is running by driving the drive wheels 72 with the motor generator 4 for running without supplying fuel to the cylinders of the internal combustion engine 1 to operate the internal combustion engine 1. , the power generation motor generator 2 performs motoring for starting the internal combustion engine 1 .

Motoring for starting the internal combustion engine 1 continues until the internal combustion engine 1 burns fuel and can rotate independently. More specifically, the rotational speed of the crankshaft of the internal combustion engine 1 being sensed rises above the minimum threshold required for starting, and the crankshaft of the internal combustion engine 1 rotates more than a predetermined number of times from the start of motoring, or reaches a predetermined speed. Motoring is terminated when the rotation is equal to or more than the angle. The condition that the crankshaft has rotated a predetermined number of times or more or a predetermined angle or more may be replaced with the completion of cylinder discrimination for obtaining the current stroke or piston position of each cylinder of the internal combustion engine 1 . It is necessary to know the current stroke of each cylinder in order to inject fuel at appropriate timing according to the stroke of each cylinder and to ignite and burn fuel at appropriate timing. Cylinder discrimination is performed by a crank angle sensor that emits a pulse signal each time the crankshaft rotates by a predetermined angle (for example, 10°CA), and a crank angle sensor that emits a pulse signal each time the crankshaft rotates by a predetermined angle (one rotation of the camshaft divided by the number of cylinders). Angle: In the case of a three-cylinder engine, this is done using a cam angle sensor that emits a pulse signal each time it rotates by 120° (240° CA). Since the method for discriminating cylinders is well known, a description thereof will be omitted here. It is necessary to rotate about a rotation. The length of time required from the start to the end of motoring is less than tenths of a second if the power storage device 3 is not out of order.

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

When the vehicle driver releases the accelerator pedal or depresses the brake pedal to perform regenerative braking, the electric power (or voltage or current) can be varied. FIG. 3 shows the relationship between the vehicle speed and deceleration of the vehicle during regenerative braking and the power generated by the motor generator 4 for traveling. In FIG. 3, the solid line represents the mode with the lowest generated power, the dashed line represents the mode with medium generated power, and the one-dot chain line represents the mode with the largest generated power. As shown in the figure, the greater the electric power generated by the traveling motor generator 4 during regenerative braking, the greater the deceleration of the vehicle.

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

On the other hand, when the driver steps on the brake pedal, the vehicle can be braked by the hydraulic brake devices 67, 68, 69, 60 attached to the wheels. However, if the brake devices 67, 68, 69, 60 are used excessively, frictional heat will overheat the brake fluid and cause it to boil, causing vapor lock in which a large amount of air bubbles are generated in the hydraulic circuit. Then, even if the brake pedal is stepped on, sufficient hydraulic pressure cannot be applied to the brake devices 67, 68, 69, 60, and the braking performance of the brake devices 67, 68, 69, 60 deteriorates.

Therefore, as shown in FIG. 4, the ECU 0 of the present embodiment detects that an event such as a vapor lock that makes normal braking by the braking devices 67, 68, 69, and 60 difficult has occurred (step S1 ), the braking force exerted by regenerative braking generated by the running motor generator 4 is gradually increased (step S2), and the mode automatically shifts to a one-pedal operation mode in which acceleration, deceleration and braking can be performed by operating only the accelerator pedal. (step S3). Concurrently with this, the driver is notified or warned that the brake devices 67, 68, 69, 60 are not working properly in a manner that appeals to the driver's sight or hearing (step S4).

In step S1, for example, based on the current depression amount of the brake pedal or the master cylinder pressure sensed via a sensor and the hydraulic pressure applied to the brake devices 67, 68, 69, 60, the vapor lock is detected. It is determined whether or not an event such as If the hydraulic pressure applied to the brake devices 67, 68, 69, 60 is small below the threshold even though the brake pedal is stepped on or the master cylinder pressure is higher than a predetermined value, vapor lock, etc. event is occurring.

Alternatively, it is also possible to determine whether an event such as vapor lock has occurred based on the current brake pedal depression amount or master cylinder pressure and vehicle deceleration sensed via a sensor. If the deceleration of the vehicle speed is small below the threshold even though the brake pedal is depressed or the master cylinder pressure is higher than a predetermined value, it means that an event such as vapor lock has occurred.

In step S2, the amount of electric power generated by the motor-generator 4 for traveling during regenerative braking is automatically changed from the mode with the lowest generated power or the medium mode to the mode with the highest generated power regardless of the intention of the driver. transition to At this time, instead of rapidly increasing the generated power from the former mode to the latter mode in a stepwise manner, by gradually increasing the generated power toward the latter mode, the braking force exerted by the running motor generator 4 is increased. Gradually increase to slow down the vehicle gradually.

In step S3, when the driver depresses the accelerator pedal or releases the brake pedal, the mode automatically shifts to the one-pedal operation mode regardless of the driver's intention. The one-pedal operation mode is a mode in which the vehicle is accelerated, decelerated, and braked only by the amount of depression of the accelerator pedal, regardless of the amount of depression of the brake pedal. When the amount of depression of the accelerator pedal by the driver is larger than a certain boundary value, it is determined that the greater the amount of depression, the greater the acceleration of the vehicle requested by the driver. increase the driving force to

On the other hand, when the amount of depression of the accelerator pedal by the driver is smaller than the boundary value, it is determined that the smaller the amount of depression, the greater the deceleration of the vehicle requested by the driver. 4 to increase the power generated by regeneration. In the mode where the generated power is the largest, the vehicle can almost or completely come to a stop when the driver releases the accelerator pedal, that is, when the amount of depression of the accelerator pedal becomes 0 or a minimum value close to 0. , the braking force exerted by the running motor generator 4 increases.

In step S4, for example, a warning lamp provided in the cockpit of the driver's seat is turned on or blinked, a warning is displayed on the screen of the display, or a buzzer or other warning sound is output.

In this embodiment, when the driver takes his/her foot off the accelerator pedal, it is possible to perform regenerative braking to brake the wheels 72 by generating power from the generator 4. In this case, the power generated by the generator 4 The size can be changed, and when an event that makes normal braking difficult occurs in the brake devices 67, 68, 69, 60 attached to the wheels 72, it is exerted by regenerative braking generated by the generator 4. A control device 0 for a vehicle is constructed which gradually increases the braking force and automatically shifts to a one-pedal operation mode in which acceleration, deceleration and braking are possible by operating only the accelerator pedal.

According to this embodiment, even when an event occurs in which normal braking becomes difficult in the brake devices 67, 68, 69, 60, a fail-safe system is realized in which the vehicle can be safely decelerated or stopped. When vapor lock occurs, the vehicle cannot be stopped even by depressing the brake pedal, and the driver may lose his composure. As long as the vehicle is braked, the danger can be avoided. Moreover, at that time, the power generated by the generator 4 that executes regenerative braking is gradually increased, and control is performed so that the braking force is gradually increased. .

The present invention is not limited to the embodiments detailed above. In particular, the object of application of the present invention is not limited to a series hybrid vehicle, as long as the vehicle is capable of performing regenerative braking to brake the wheels by generating electricity with a generator.

In addition, the specific configuration of each part and the content of processing can be modified in various ways without departing from the gist 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 unit (ECU)
DESCRIPTION OF SYMBOLS 1... Internal-combustion engine 3... Electricity storage apparatus 4... Generator (motor generator for driving|running|working)
67, 68, 69, 60... Brake device

Claims (1)

When the driver takes his/her foot off the accelerator pedal, it is possible to perform regenerative braking by generating electricity from the generator to brake the wheels. There is
Based on the current brake pedal depression amount or master cylinder pressure and the hydraulic pressure applied to the brake device attached to the wheel, or based on the current brake pedal depression amount or master cylinder pressure and the deceleration of the vehicle speed Based on this, it is determined whether or not a vapor lock that makes normal braking difficult occurs in the brake device,
If it is determined that vapor lock has occurred,
increasing the braking force exerted by regenerative braking generated by the generator compared to when it is not determined that vapor lock is occurring ,
In addition, the vehicle automatically shifts to a one-pedal operation mode in which acceleration, deceleration, and braking can be performed by operating only the accelerator pedal, and when the driver releases the accelerator pedal, the amount of depression of the accelerator pedal becomes 0 or a minimal value close to 0. A control device for a vehicle that sometimes increases the braking force exerted by the generator to such an extent that the vehicle can be almost or completely stopped .

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