JP2020138635A - Control device for hybrid vehicle - Google Patents

Abstract

To realize a response which is coincident with intention of an operator who demands quick acceleration in a hybrid vehicle.SOLUTION: A control device controls a hybrid vehicle comprising an electric motor for travel which can supply travel drive power to a drive wheel, an internal combusting engine which can supply drive power for electric power generation to a power generator which generates electric power to be supplied to the electric motor for travel, and an electric motor for motoring which can supply drive power for rotating the internal combustion engine to the internal combustion engine. The control device supplies a fuel to the internal combustion engine to burn the fuel while performing motoring of the internal combustion engine by the electric motor for motoring when starting the stopped internal combustion engine to execute power generation, and thereafter, when determining that the internal combustion engine performs self-supporting rotation even if reducing output of the electric motor for motoring, starts power generation by a power generator before an engine speed reaches a final target speed.SELECTED DRAWING: Figure 3

Description

The present invention relates to a control device for controlling a hybrid vehicle equipped with a traveling electric motor and an internal combustion engine.

Recently, hybrid vehicles equipped with two types of power sources, an electric motor and an internal combustion engine, have seen a certain degree of widespread use. In series hybrid vehicles (see, for example, the patent documents below), an internal combustion engine drives a motor generator for power generation to generate electricity, and the generated power is stored in a power storage device (battery and / or capacitor) and a traveling motor. Supply to the generator. Then, the drive wheels of the vehicle are rotated by the traveling motor generator to travel.

Not only the power generation motor generator but also the traveling motor generator can generate power by regenerative braking and store the generated power in the power storage device. When the electric charge has already been stored up to the capacity of the power storage device, the electric power obtained by regenerative braking is intentionally supplied to the power generation motor generator, which is operated as an electric motor to rotate and drive the internal combustion engine, thereby surplus. Consume power.

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

When the amount of electric charge currently stored in the power storage device is less than a predetermined amount, or when the required output for the traction motor generator is large, the internal combustion engine is started to supply fuel to the cylinder and burn it. The motor generator for power generation is driven by the rotational driving force output from the internal combustion engine to generate electricity to charge the power storage device or increase the power supplied to the motor generator for traveling.

In a series hybrid vehicle, the power generation motor generator also serves to motor (or crank) the internal combustion engine in preparation for starting the stopped internal combustion engine. At the time of motoring, the necessary electric power is supplied from the power storage device.

JP-A-2016-064735

In order to drive the motor generator for power generation by the internal combustion engine to generate power from the situation where the motor generator for power generation is not generating power, the internal combustion engine burns fuel and rotates autonomously to output the required rotational driving force. It needs to be ready.

In the existing system, when the stopped internal combustion engine is started to generate power, the internal combustion engine is motorized by a power generation motor generator to accelerate the engine speed to the required speed (for example, 600 rpm), and then Fuel is supplied to the cylinder of the internal combustion engine to start ignition and combustion of the fuel in the internal combustion engine. Further, after continuing the motoring to raise the engine speed to an efficient speed (for example, 2000 rpm), the motoring is terminated, and the power generation amount motor generator is driven by the internal combustion engine to start power generation.

That is, in the existing system, even after the internal combustion engine is started and starts to rotate independently, power generation is not performed until the engine speed reaches an efficient region. If this is the case, when the driver strongly depresses the accelerator pedal to request acceleration of the vehicle, it may not be possible to realize an acceleration response that meets the request. In particular, when the capacity of the power storage device installed in the vehicle is small, or when the amount of electric charge currently stored in the power storage device is small, after the driver requests acceleration, until the motor generator for power generation actually starts power generation. During the period, there is a concern that the driving motor generator cannot be supplied with sufficient electric power.

An object of the present invention is to realize a response that matches the intention of a driver who demands rapid acceleration in a hybrid vehicle having two types of power sources, an electric motor and an internal combustion engine.

In the present invention, a traveling electric motor capable of supplying driving force for traveling to the driving wheels, an internal combustion engine capable of supplying driving force for power generation to a generator for generating electric power to be supplied to the traveling electric motor, and an internal combustion engine. It controls a hybrid vehicle equipped with a motoring electric motor capable of supplying a driving force for rotating the internal combustion engine, and when starting a stopped internal combustion engine to generate power, the motoring electric motor is used. If it is determined that the internal combustion engine rotates autonomously even if the output of the motoring motor is reduced after supplying fuel to the internal combustion engine and burning it while motorizing the internal combustion engine, the engine rotation speed is increased. A control device was configured to start power generation by the generator before reaching the target rotation speed.

According to the present invention, in a hybrid vehicle, it is possible to realize a response that matches the intention of the driver who demands rapid acceleration.

The figure which shows the outline of the series type hybrid vehicle and the control device in one Embodiment of this invention. The figure which shows the classification of the request output in the control performed by the control device of the same embodiment. The flow chart which shows the procedure of the processing in the control carried out by the control apparatus of the same embodiment. The timing diagram which illustrates the transition of the engine speed and the output of the motor generator for power generation in the control carried out by the control device of the same embodiment.

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. This hybrid vehicle includes an internal combustion engine 1, a power generation motor generator 2 driven by the internal combustion engine 1 to generate electricity, a power storage device 3 for storing the electric power generated by the power generation motor generator 2, a power generation motor generator 2 and /. Alternatively, it is provided with a traveling motor generator 4 that drives the drive wheels 62 of the vehicle by receiving power supplied from the power storage device 3.

The hybrid vehicle of the present embodiment is a series hybrid type electric vehicle that uses the internal combustion engine 1 only for power generation, and the driving force for traveling is supplied exclusively to the driving wheels 62 of the vehicle from the traveling motor generator 4. The internal combustion engine 1 and the drive wheels 62 are mechanically separated from each other, and the rotational driving force is not originally transmitted between the two. That is, the internal combustion engine 1 can rotate completely independently of the traveling motor generator 4 and the drive wheels 62. Therefore, the power storage device 3 is sufficient even when the vehicle can be driven by the driver pressing the accelerator pedal during operation of the vehicle in which the ignition switch (power switch or ignition key) is operated to be ON. Under the condition of storing electric charge, the operation of the internal combustion engine 1 accompanied by the combustion of fuel may not be performed.

The internal combustion engine 1 is, for example, a 4-stroke engine including a plurality of cylinders. The crankshaft, which is the rotating shaft of the internal combustion engine 1, is mechanically connected to the rotating shaft of the power generation motor generator 2 via a gear mechanism. Then, by inputting the rotational driving force output by the internal combustion engine 1 to the power generation motor generator 2, the power generation motor generator 2 generates power. The generated electric power charges the power storage device 3 and / or supplies it to the traveling motor generator 4. In addition, the 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 executes motoring (cranking) in preparation for starting the stopped internal combustion engine 1.

The traveling motor generator 4 generates a driving force for traveling the vehicle, and inputs the driving force to the drive wheels 62 via the speed reducer 61. Further, the traveling motor generator 4 is rotated by being rotated by the drive wheels 62 to generate electricity, 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 the charge has already been stored up to the capacity of the power storage device 3 and it is difficult to charge the battery any more, the power generated by the traveling motor generator 4 is intentionally supplied to the power generation motor generator 2 to generate electricity. The motor generator 2 is operated as an electric motor to rotationally drive the internal combustion engine 1. As a result, the surplus electric power is exhausted while maintaining the braking performance of the vehicle. Further, at this time, since the rotation of the internal combustion engine 1 is maintained, it is possible to execute a fuel cut that temporarily stops the fuel supply to the cylinder of the internal combustion engine 1.

The 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 the power storage device 3 or the drive unit inverter 41. Further, when the generator inverter 21 operates the power generation motor generator 2 as an electric motor, the power generation motor generator 2 converts the DC power supplied from the power storage device 3 and / or the drive inverter 41 into AC power. Enter in.

The drive machine inverter 41 converts the DC power supplied from the power storage device 3 and / or the generator inverter 21 into AC power, and then inputs the DC power to the traveling motor generator 4. Further, the drive inverter 41 converts the AC power generated by the traveling motor generator 4 into DC power when the vehicle is regeneratively braked, and then inputs the AC 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 the 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 the electric power generated by each of the power generation motor generator 2 and the traveling motor generator 4. In addition, the power storage device 3 discharges electric power for operating each of the power generation motor generator 2 and the traveling motor generator 4 as an electric motor, and supplies the electric power required for the motor generators 2 and 4.

The ECU (Electronic Control Unit) 0, which 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, 41, and the traveling motor generator 4, is a processor, a memory, an input interface, an output interface, and the like. It is a microcomputer system having. The ECU 0 includes a plurality of ECUs, that is, an engine controller 01 that controls an internal combustion engine 1, a generator controller 02 that controls a power generation motor generator 2 and a generator inverter 21, a battery controller 03 that controls a power storage device 3, and a traveling motor. The drive controller 04 and the like that control the generator 4 and the drive inverter 41 are connected to each other so as to be able to communicate with each other via a telecommunications line such as a CAN (Control Area Network).

The ECU 0 senses the accelerator opening operated by the driver, that is, the amount of depression of the accelerator pedal, the shift position, that is, the position of the shift lever or selector lever, or the ON / OFF of the switch, and the vehicle speed of the current vehicle, which is sensed through the sensor. , 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 generation according to the slope of the road surface, the amount of electricity stored in the power storage device 3, the generated power of the power generation motor generator 2, and the like. The magnitude of the electric power generated by the motor generator 2 is controlled to increase or decrease.

When the power storage device 3 currently stores sufficient electric charge and the output required for the traveling motor generator 4 is small, the supply of fuel to the internal combustion engine 1 is cut off and the internal combustion engine 1 is not operated. On the other hand, if the amount of electric charge currently stored in the power storage device 3 is less than a predetermined amount, or if the output required for the traveling motor generator 4 is large, the internal combustion engine 1 is started and the cylinder is charged. Fuel is supplied and burned, and the power generation amount motor generator 2 is driven by the rotational driving force output by the internal combustion engine 1, and power is generated to charge the power storage device 3 or supply it to the traveling motor generator 4. Increase power.

FIG. 2 shows the relationship between the output required by the driver of the vehicle and the necessity of operating the internal combustion engine 1 and the power generation motor generator 2. The required output is determined by the accelerator opening and the vehicle speed operated by the driver. As a general rule, the required output increases as the accelerator opening increases, and increases as the vehicle speed increases. In FIG. 2, the required output becomes larger toward the upper right. In the low output region I where the driving force to be applied to the drive wheels 62 is relatively small and the vehicle speed is relatively low, the ECU 0 stops its operation without supplying fuel to the internal combustion engine 1 and generates a power generation motor generator 2. Do not operate as a machine. In the low output region I, the traveling motor generator 4 receives electric power only from the power storage device 3 and outputs a driving force for traveling the vehicle.

On the other hand, the ECU 0 supplies fuel to the internal combustion engine 1 and operates the internal combustion engine 1 in the medium and high output regions II and III in which the driving force to be applied to the drive wheels 62 is larger than a certain level or the vehicle speed is higher than a certain level, and the power generation motor The generator 2 is operated as a generator. In the medium output region II where the required output is not remarkably large, the traveling motor generator 4 mainly receives electric power from the power generation motor generator 2 and outputs the driving force for traveling the vehicle. At this time, a small amount of power is supplied from the power storage device 3, or no power is supplied at all. In the high output region III in which the required output is remarkably large, the traveling motor generator 4 receives electric power from both the power generation motor generator 2 and the power storage device 3 and outputs the driving force for traveling the vehicle.

The internal combustion engine 1 is started while the drive wheels 62 are driven by the traveling motor generator 4 to drive the vehicle without supplying fuel to the cylinders of the internal combustion engine 1 to operate the internal combustion engine 1. In order to execute power generation by the power generation motor generator 2, first, the power generation motor generator 2 is operated as an electric motor, whereby motoring for starting the internal combustion engine 1 is performed.

Specifically, as shown in FIG. 3, the crankshaft of the internal combustion engine 1 is rotationally driven by the power generation motor generator 2 (step S1), and the crankshaft of the internal combustion engine 1 rotates a predetermined number of times or more or a predetermined angle or more. After the cylinder determination to know the current stroke of each cylinder of the internal combustion engine 1 or the position of the piston is completed, the fuel is injected at an appropriate timing according to the stroke of each cylinder of the internal combustion engine, and the fuel is injected at an appropriate timing. The firing is started (step S2). The rotation angle and rotation speed of the crankshaft of the internal combustion engine 1, that is, the engine speed, can be detected via a known resolver attached to the motor generator 2 for power generation (in the generator controller 02), and is attached to the internal combustion engine 1. It can also be detected (in the engine controller 01) via a known crank angle sensor.

Then, whether or not the internal combustion engine 1 is able to rotate autonomously and output the rotational driving force required for power generation, in other words, even if the output of the power generation motor generator 2 is reduced, the engine speed is still high. Determines whether or not the upward trend can be maintained (step S3). In step S3, as shown in FIG. 4, after t1 when the engine speed reaches the required speed T1 or more, the output of the power generation motor generator 2 operating as an electric motor is reduced, and the engine speed is still reduced. See if it rises without falling. The rotation speed T1 is set to an appropriate value within the range of, for example, about 600 rpm to 800 rpm. If the engine speed does not decrease and rises even if the output of the power generation motor generator 2 is reduced, it is determined that the internal combustion engine 1 is in a state of autonomous rotation. Alternatively, after the firing of the internal combustion engine 1 is started, the magnitude of the current flowing through the coil of the power generation motor generator 2 operating as an electric motor or the magnitude of the voltage applied to the coil is monitored, and the magnitude of the current or voltage is determined. It may be determined that the internal combustion engine 1 is in a state of autonomously rotating when the amount of the internal combustion engine 1 decreases by a predetermined amount or more per unit time. The decrease in the applied current or applied voltage to the coil of the power generation motor generator 2 means that the mechanical load on the power generation motor generator 2 is reduced as a result of the internal combustion engine 1 outputting the rotational driving force. To do.

If it is determined that the internal combustion engine 1 rotates autonomously and is ready to output the required rotational driving force, the output of the power generation motor generator 2 operating as an electric motor is output as shown in FIG. The motoring is completed by reducing the number to 0, and this time, the internal combustion engine 1 rotationally drives the power generation motor generator 2 (step S4). Further, the power generation motor generator 2 is operated as a generator, and the generated power is increased from 0 (step S5). Then, the intake amount and fuel injection amount supplied to the cylinder 1 of the internal combustion engine 1 and the power generation motor generator 2 so that the engine rotation speed follows the target rotation speed gradually increasing from the rotation speed T1. Feedback control for increasing or decreasing the generated power is performed (step S6). The target rotation speed finally rises to the rotation speed T2. The final target rotation speed T2 is set to a rotation speed that is most advantageous for the fuel consumption rate, for example, about 2000 rpm, at which the internal combustion engine 1 can be operated with optimum or near-optimal efficiency. Alternatively, the final target rotation speed T2 may be set to a rotation speed at which the internal combustion engine 1 can achieve the maximum torque or maximum output or a torque or output close to the maximum torque or output. Which of the final target rotation speeds T2 is to be determined may be determined according to the size of the accelerator opening operated by the driver and / or the amount of expansion of the accelerator opening per unit time. If it is considered that the driver requires rapid acceleration, it is conceivable that the final target rotation speed T2 is the latter.

During the period (from time point t1 to time point t2) when the engine speed is between the above speed T1 and the final target speed T2, a part of the rotation driving force output by the internal combustion engine 1 is used as the engine speed. While spending on acceleration, the rest is allocated to power generation by the power generation motor generator 2, that is, acceleration and power generation are carried out in parallel. In the feedback control of the engine speed during the period, when the measured speed detected through the resolver or the crank angle sensor is lower than the target speed, the generated power or output voltage of the power generation motor generator 2 operating as a generator. Or reduce the output current. By doing so, the mechanical load on the internal combustion engine 1 can be reduced, and the acceleration of the engine speed can be further increased. On the contrary, when the actually measured engine speed exceeds the target speed, the generated power, output voltage, or output current of the power generation motor generator 2 is increased. Then, the mechanical load on the internal combustion engine 1 increases, and the acceleration of the engine speed can be suppressed.

Then, after t2 (step S7) when the engine speed reaches the final target speed T2, power generation by the power generation motor generator 2 is continued while maintaining the engine speed at the speed T2 (step). S8). After t2 when the engine speed reaches the target speed T2, it is not necessary to accelerate the engine speed any more, and most of the rotational driving force output by the internal combustion engine 1 is used for power generation by the power generation motor generator 2. be able to. The generated power, output voltage, or output current of the power generation motor generator 2 at this time is the generated power, output voltage, or output current of the power generation motor generator 2 during the acceleration period before the time t2 when the engine speed reaches the target speed T2. It will be larger than the output current.

In the present embodiment, the traveling electric motor 4 that can supply the driving force for traveling to the drive wheels 62 and the internal combustion that can supply the driving force for power generation to the generator 2 that generates the electric motor to be supplied to the traveling electric motor 4. It controls a hybrid vehicle including an engine 1 and a motoring electric motor 2 capable of supplying a driving force for rotating the internal combustion engine 1 to the internal combustion engine 1, and starts a stopped internal combustion engine 1. When generating power, the motoring electric motor 2 motors the internal combustion engine 1 while supplying fuel to the internal combustion engine 1 to burn it (steps S1 and S2), and then reducing the output of the motoring electric motor 2. Even so, if it is determined that the internal combustion engine 1 rotates autonomously (step S3), the internal combustion engine 1 promptly drives the generator 2 before the engine rotation speed reaches the final target rotation speed T2. The control device 0 for starting the power generation by the generator 2 (steps S4 to S6) was configured.

In the conventional control in the hybrid vehicle, even if the internal combustion engine 1 accelerates to the minimum required rotation speed T1 or more for its self-sustaining rotation, until the engine rotation speed reaches the efficient rotation speed T2. The generator 2 was continuously operated without load, and the power generation by the generator 2 was not started. On the other hand, in the control of the present embodiment, after the internal combustion engine 1 accelerates to the minimum required rotation speed T1 or more, the generator 2 is immediately loaded and operated to start power generation by the generator 2.

According to the present embodiment, when the vehicle speed is low or the driving force output by the traveling electric motor 4 is small and the driver depresses the accelerator pedal to request acceleration of the vehicle, the generator is generated as soon as possible. The generated power of 2 can be supplied to the traveling electric motor 4. Then, the traveling electric motor 4 can generate a driving force sufficient to achieve acceleration that matches the driver's intention and input the driving force to the drive wheels 62. As a result, it is possible to accelerate the vehicle without delay.

In particular, in this embodiment, the necessary and sufficient power performance is exhibited when the capacity of the power storage device 3 mounted on the vehicle is originally small or when the amount of electric charge currently stored in the power storage device 3 is small. It works for. This is useful in a small vehicle in which a large and large capacity power storage device 3 is mounted and space is scarce. In addition, it is also advantageous for avoiding weight increase and cost increase due to mounting the large-sized and large-capacity power storage device 3.

The present invention is not limited to the embodiments described in detail above. For example, after the engine speed of the started internal combustion engine 1 accelerates to the required speed T1, the power generation by the generator 2 is not always started, but the acceleration required by the driver indicated by the accelerator opening is equal to or higher than a predetermined value. Only when the amount of electricity currently stored in the power storage device 3 is reduced below a predetermined value, the generator 2 immediately starts power generation, or the engine speed is the final target. The power generation by the generator 2 may not be started until the rotation speed T2 is reached.

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

The present invention can be applied to the control of a hybrid vehicle.

0 ... Control unit (ECU)
1 ... Internal combustion engine 2 ... Generator, motoring motor (motor generator for power generation)
4 ... Driving motor (driving motor generator)
3 ... Power storage device 62 ... Drive wheels

Claims (1)

A driving motor that can supply driving force to the driving wheels for driving,
An internal combustion engine that can supply the driving force for power generation to the generator that generates the electric power that should be supplied to the traction motor.
It controls a hybrid vehicle equipped with a motoring electric motor capable of supplying an internal combustion engine with a driving force for rotating the internal combustion engine.
When starting a stopped internal combustion engine to generate power, the motoring electric motor is used to motor the internal combustion engine while supplying fuel to the internal combustion engine to burn it, and then reducing the output of the motoring electric motor. A control device that starts power generation by a motor before the engine speed reaches the target speed if it is determined that the internal combustion engine rotates autonomously.

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