JP6238508B2 - Control device for hybrid electric vehicle - Google Patents

Description

  The present invention relates to a control apparatus for a hybrid electric vehicle including an engine and an electric motor as a driving source for traveling, and more particularly to traveling control when the vehicle starts.

In recent years, hybrid electric vehicles including an engine and an electric motor as driving sources for traveling have been developed for the purpose of improving fuel consumption and exhaust gas performance.
Among hybrid electric vehicles, there is a vehicle capable of so-called creep running that gives a driving force to the vehicle without depressing an accelerator from a vehicle stopped state. Originally creep travel occurs when a torque converter or the like is provided between the engine and the drive wheel. In a hybrid electric vehicle, this creep travel is simulated by the driving force of an electric motor (Patent Document). 1).

JP 2001-310654 A

Even in the case of a hybrid electric vehicle that performs creep running using the driving force of an electric motor as in Patent Document 1, the amount of power stored in a battery that supplies electric power to the electric motor (hereinafter referred to as SOC: State Of Charge) is low. If it is difficult to use the electric motor, etc., creep running using the engine is performed.
However, in hybrid electric vehicles, driving using an electric motor is often prioritized for improving fuel efficiency, and the accelerator is depressed during creep driving by the engine and switched to normal driving control according to the required torque. There is a problem that the mode is shifted to a traveling mode in which the electric motor is used even though the SOC is low.

After that, even if the engine is switched to engine driving due to low SOC or the like in normal driving control, the SOC is further consumed by temporarily driving by the electric motor, or the driver is frequently switched because the driving source is frequently switched. There is a risk of reducing the performance.
The present invention has been made to solve such a problem, and the purpose of the present invention is to further reduce the SOC during the transition from creep running to normal running when it is difficult to use the electric motor. It is another object of the present invention to provide a control device for a hybrid electric vehicle capable of preventing the deterioration of drivability and preventing the deterioration of drivability.

In order to achieve the above-described object, the hybrid electric vehicle control apparatus according to claim 1 is a hybrid electric vehicle control apparatus including an engine and an electric motor as a driving source for traveling. A clutch provided between the engine for connecting and disconnecting the driving force of the engine transmitted from the engine to the drive wheels via the electric motor, and whether or not the electric motor can be used as a driving source when starting the vehicle If the use of the electric motor is determined by the electric motor use determination means and the electric motor use determination means before the start of creep running, it is determined that the accelerator is not depressed. Meanwhile the Hare rows creeping, is judged not to be possible to use the electric motor by said electric motor use determination means before the start of the creep running If the in the absence of depression of the accelerator have rows creep running of using always the only engine the clutch as half clutch state, the traveling using the engine by connecting the clutch and accelerator Ru depressed Start control means for controlling the motor to be used, and the electric motor use determining means is configured to use the electric motor use determining means when the electric storage amount of the battery that supplies electric power to the electric motor is smaller than a predetermined electric storage amount. It is characterized in that it is determined that the use of is not possible.

  According to the hybrid electric vehicle control apparatus of the first aspect of the present invention using the above-described means, when the electric motor can be used, creep driving is performed by the electric motor, and when the electric motor cannot be used, the half-clutch state is set. A creep running is performed using the engine, and when the accelerator is depressed, the clutch is connected to maintain the running using the engine.

  Thereby, when it is difficult to use the electric motor, it is possible to smoothly shift from the creep traveling by the engine to the normal traveling without shifting to the traveling by the electric motor. Accordingly, it is possible to prevent a further decrease in the SOC during the transition from the creep travel to the normal travel, and to suppress a decrease in drivability.

Furthermore, in determining whether or not the electric motor can be used as a driving source for traveling, if at least the amount of charge (SOC) of the battery is a condition and the SOC is smaller than a predetermined SOC, the use of the electric motor is It is determined that it is not possible.
As a result, it is possible to reliably prevent a further decrease in the SOC during the transition from creep running to normal running.

It is a schematic block diagram of the control apparatus of the hybrid electric vehicle in one Embodiment of this invention. It is a flowchart which shows the traveling control routine at the time of vehicle start which ECU of the control apparatus of the hybrid electric vehicle which concerns on one Embodiment of this invention performs.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing a schematic configuration of a control apparatus for a hybrid electric vehicle according to an embodiment of the present invention, which will be described with reference to FIG.
A vehicle 1 shown in FIG. 1 is a hybrid electric vehicle including an engine 2 and a motor 4 (electric motor) as drive sources.

The engine 2 is a prime mover that is generally used in automobiles such as a diesel engine and a gasoline engine, and the type thereof is not particularly limited here.
A clutch 6 is provided between the engine 2 and the motor 4, the output shaft of the engine 2 is on the input shaft (input side) of the clutch 6, and the motor is on the output shaft (output side) of the clutch 6. The four rotation shafts are connected to each other.

  The motor 4 is, for example, a permanent magnet type synchronous motor that can generate power, and the rotating shaft of the motor 4 is connected to the input shaft of the transmission 8. The transmission 8 includes a plurality of gears, shifts the driving force input through the gears corresponding to the selected shift speed, and transmits them to the output shaft of the transmission 8. The drive force is transmitted from the output shaft of the transmission 8 to the left and right drive wheels 16 via the propeller shaft 10, the differential device 12, and the drive shaft 14.

  The motor 4 is connected to a battery 18 mounted on the vehicle 1 via an inverter 20, and receives torque from the battery 18 to generate torque. The battery 18 is a secondary battery such as lithium ion or nickel metal hydride, and the inverter 20 converts the DC power from the battery 18 into AC power and supplies the motor 4 with power. On the other hand, when the vehicle is decelerated, the motor 4 functions as a generator and is regeneratively driven. That is, the motor 4 generates AC power by the driving force transmitted in reverse from the driving wheels 16, and the regenerative torque generated by the motor 6 at this time acts as a braking torque for the driving wheels 16 and functions as a so-called regenerative brake. . The AC power is converted into DC power by the inverter 20 and then charged to the battery 18 so that the kinetic energy due to the rotation of the drive wheels 16 is recovered as electric energy.

In the vehicle 1 having such a configuration, only the rotating shaft of the motor 4 is mechanically connected to the drive wheels 16 via the transmission 8 when the clutch 6 is in the disconnected state. That is, only the torque generated by the motor 4 (hereinafter referred to as motor torque) is transmitted to the drive wheels 16 as the drive torque or braking torque of the vehicle 1.
On the other hand, when the clutch 6 is in the connected state, the output shaft of the engine 2 is mechanically connected to the transmission 8, the drive wheels 16 and the like via the rotating shaft of the motor 4. That is, at this time, when the motor torque is set to 0 and only the engine 2 is operated, only the torque generated by the engine 2 (hereinafter referred to as engine torque) becomes the driving torque or braking torque of the vehicle 1. At this time, if the motor 4 is also operated, the sum of the motor torque and the engine torque becomes the driving torque or braking torque of the vehicle 1.

The vehicle 1 is equipped with an ECU (Electronic Control Unit) 22 that integrally controls the engine 2, the motor 4, the clutch 6, and the transmission 8 in order to adjust the distribution of the motor torque and the engine torque. Has been.
The ECU 22 is communicably connected to each control unit (not shown) of the engine 2, the electric motor 4, the clutch 6, and the transmission 8 using a CAN (Controller Area Network) or the like. For example, the ECU 22 sends engine speed information from the engine 2, motor speed information from the motor 4, motor torque information and motor 4 temperature information, currently selected gear stage information from the transmission 8, SOC information from the battery 18, and Various information such as temperature information of the battery 18 and temperature information of the inverter 20 is acquired from the inverter 20.

Further, the vehicle 1 is provided with an accelerator sensor 24 for detecting the accelerator depression amount, and the accelerator sensor 24 is also connected to the ECU 22 so as to be able to transmit information.
The ECU 22 configured as described above monitors the SOC of the battery 18 and the driving state of the vehicle 1, optimizes the fuel consumption and exhaust gas performance, and performs the operation in accordance with the driving request of the engine 2, the electric motor. 4. Control the clutch 6, the transmission 8, etc.

  For example, the ECU 22 determines whether or not the motor 4 can be used as a driving source for traveling (electric motor use determining unit), and the accelerator is not depressed from the vehicle stop state using the driving source according to the determination. Even in such a case, creep traveling control for generating a driving force is performed, and when the accelerator is depressed, normal traveling control corresponding to the required torque is performed (start control means).

Hereinafter, the travel control at the time of vehicle start performed by the ECU 22 will be described in detail.
Referring now to FIG. 2, there is shown a flowchart showing a travel control routine executed by the ECU 22 at the time of vehicle start, which will be described below with reference to the flowchart. The control is executed from a state where the vehicle 1 is stopped, for example.
First, as step S1, the ECU 22 determines whether or not a condition for performing creep travel by motor torque (hereinafter referred to as motor creep travel) is satisfied. The motor creep traveling condition is a condition in which the motor 4 can be used as a driving source for traveling. Specifically, the SOC of the battery 18 is equal to or higher than a predetermined SOC required for motor creep traveling. It is assumed that the motor creep travel condition is satisfied when the temperature state of each of the inverter 18 and the inverter 20 is in a normal range. If the determination result is true (Yes), the process proceeds to step S2.

  In step S2, the ECU 22 performs motor creep travel. The motor creep travel is performed by causing the clutch 6 to be disconnected and generating a predetermined creep torque by the motor 4. For example, the creep torque is set to a driving torque that does not cause the vehicle 1 to move backward even when the vehicle starts on an uphill road. Further, the creep torque may be changed according to the speed selected in the transmission 8.

  In subsequent step S3, the ECU 22 determines whether or not there is an accelerator depression (accelerator ON) based on the accelerator opening information from the accelerator sensor 24. When the determination result is false (No), that is, while the accelerator is not depressed, the process returns to step S2 and the motor creep running is maintained. On the other hand, if the determination result is true (Yes), that is, if the accelerator is depressed, the process proceeds to step S4.

  In step S4, the ECU 22 calculates a torque required for the vehicle 1 (hereinafter referred to as a required torque) based on the accelerator opening information from the accelerator sensor 24, the speed of the vehicle 1, etc., and the required torque is determined in advance. It is determined whether or not the torque is greater than the torque. The predetermined torque corresponds to, for example, the maximum torque that the motor 4 can use during normal travel. If the determination result is false (No), that is, if the required torque can be achieved only by the motor torque, the process proceeds to step S5.

In step S5, the ECU 22 controls to shift to a travel mode (hereinafter referred to as a motor travel mode) using only the motor 4 as a drive source with the clutch disengaged, and to achieve the required torque only by the motor torque.
On the other hand, if the determination result in step S4 is true (Yes), that is, if the required torque cannot be achieved only by the motor torque, the process proceeds to step S6.

  In step S6, the ECU 22 connects the clutch 6 to shift to a travel mode (hereinafter referred to as a hybrid travel mode) using the motor 4 and the engine 2 as drive sources, and performs control to achieve the required torque by the motor torque and the engine torque. To do. For example, in the hybrid travel mode, the ECU 22 achieves the required torque by setting the motor torque as the maximum torque that can be used in normal travel and adding the shortage to the engine torque.

In step S1, if the SOC of the battery 18 is smaller than the predetermined SOC or the temperature state of any of the motor 4, the battery 18 and the inverter 20 is outside the normal range, the ECU 22 Is not satisfied, the determination result is false (No), and the process proceeds to step S7.
In step S <b> 7, the ECU 22 executes a creep travel (hereinafter referred to as an engine creep travel) using engine torque. The engine creep travel is performed by causing the engine 2 to generate a predetermined creep torque in a so-called half-clutch state by gradually connecting the clutch 6. The creep torque may be the same as the creep torque in motor creep travel.

  In the next step S8, the ECU 22 determines whether or not the accelerator is depressed as in step S3. When the determination result is false (No), that is, while the accelerator is not depressed, the process returns to step S7 and the engine creep running is maintained. On the other hand, if the determination result is true (Yes), the process proceeds to step S9.

In step S9, the ECU 22 completely connects the clutch 6 in the half-clutch state, shifts to a travel mode (hereinafter referred to as engine travel mode) using only the engine 2 as a drive source, and achieves the required torque only by the engine torque. Control to do.
ECU22 complete | finishes the said routine, after shifting to each driving mode in said step S5, S6, S9.

As described above, the ECU 22 performs the motor creep traveling when the motor 4 can be used from the information such as the SOC, and improves the fuel efficiency of the engine 2 by traveling using the motor 4 even after the accelerator is depressed. Plan.
On the other hand, when the motor 4 cannot be used, the engine creep travel is performed, and the travel using the engine 2 is maintained without shifting to the motor travel even after the accelerator is depressed. The creep driving condition for determining whether or not the motor 4 is usable is that the motor 4 is not used when the SOC of the battery 18 is smaller than the predetermined SOC. Therefore, it is possible to reliably prevent the SOC from being further lowered during the transition from normal to traveling.

  From the above, when it is difficult to use the motor 4, it is possible to smoothly shift from creep traveling by the engine 2 to normal traveling without shifting to traveling by the motor 4. Therefore, it is possible to prevent a further decrease in SOC during the transition from the creep travel to the normal travel, and to suppress a decrease in drivability.

Although the description of the embodiment of the control apparatus for a hybrid electric vehicle according to the present invention is finished above, the embodiment is not limited to the above embodiment.
In the above-described embodiment, after the accelerator is depressed from engine creep travel, the engine travel mode is entered. However, when rapid acceleration or the like is required, a hybrid that also adds motor torque within the usable SOC range. You may make it transfer to driving mode.

1 Vehicle 2 Engine 4 Motor (electric motor)
6 Clutch 8 Transmission 16 Drive wheel 18 Battery 22 ECU (Electric motor use determination means, start control means)
24 Accelerator sensor

Claims (1)

A control device for a hybrid electric vehicle including an engine and an electric motor as a driving source for traveling,
A clutch provided between the engine and the electric motor for connecting and disconnecting the driving force of the engine transmitted from the engine to the driving wheels via the electric motor;
Electric motor use determining means for determining whether or not the electric motor can be used as a drive source when starting the vehicle;
If it is determined that it is possible to use the electric motor by said electric motor use determination means before the start of the creep running, whereas earthenware pots row creep running of using the electric motor in the absence of depression of the accelerator, the creeping If it is determined not to be possible to use the electric motor by said electric motor use determination means before the start, row physician creep running of using always the only engine the clutch as half-clutch state in the absence of depression of the accelerator is comprises a start control means for controlling to perform traveling using the engine by connecting the clutch and accelerator Ru depressed, and
The electric motor use determining means determines that the electric motor is not usable by the electric motor use determining means when at least a storage amount of a battery that supplies electric power to the electric motor is smaller than a predetermined electric storage amount. Control device for hybrid electric vehicle.

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