JP7768091B2 - Vehicle control device - Google Patents

Description

The present invention relates to a vehicle control device.

Vehicles equipped with an internal combustion engine and two electric motors are known (see, for example, Patent Document 1).

Japanese Patent Application Laid-Open No. 2020-093602

The torque generated by the electric motor rotates the internal combustion engine, causing it to start. The torque generated by the electric motor suppresses vehicle vibrations (vibration damping control). Vibration damping control continues while the internal combustion engine continues to start. If the vibration damping control continues for a long time, there is a risk that the startability of the internal combustion engine will deteriorate. Therefore, the objective is to provide a vehicle control device that can improve the startability of the internal combustion engine.

The above objective can be achieved by a vehicle control device that includes an internal combustion engine, a first electric motor, and a second electric motor, and that includes a start control unit that performs start processing of the internal combustion engine using torque output by at least one of the first electric motor and the second electric motor, and a vibration damping control unit that performs vibration damping control using the first electric motor and the second electric motor, and that stops the vibration damping control if the duration of the start processing of the internal combustion engine is equal to or longer than a predetermined time.

The start control unit may perform the start process of the internal combustion engine using only the torque output by the first electric motor.

During the vibration damping control, the first electric motor and the second electric motor output torque in a direction opposite to the rotational direction of the internal combustion engine, and during the start-up process, the first electric motor outputs torque in the same direction as the rotational direction, and after the vibration damping control is stopped, the start-up control unit may reduce the torque output by the first electric motor in the direction opposite to the rotational direction of the internal combustion engine and increase the torque in the same direction as the rotational direction.

It is possible to provide a vehicle control device that can improve the startability of an internal combustion engine.

FIG. 1 is a schematic diagram of a vehicle according to this embodiment. FIG. 2 is a flowchart illustrating the processing executed by the ECU. FIG. 3 is a diagram illustrating a time chart.

FIG. 1 is a schematic diagram of a vehicle 1 according to this embodiment. The vehicle 1 is a hybrid vehicle and includes an ECU (Electronic Control Unit) 50, an engine 10 (internal combustion engine), a first motor generator (hereinafter referred to as the "first MG (Motor Generator)") 14 (first electric motor), a second motor generator (hereinafter referred to as the "second MG") 15 (second electric motor), a PCU (Power Control Unit) 17, a battery 18, a torsional damper 19, a power split mechanism 20, a reduction mechanism 22, a differential gear 24, and drive wheels 26. The engine 10 may be a gasoline engine or a diesel engine. The engine 10, the first MG 14, and the second MG 15 are the power sources for driving the vehicle 1.

The first MG 14 and the second MG 15 function as an electric motor and a generator. When drive power is supplied to the first MG 14 and the second MG 15, they output torque, and when torque is applied to them, they generate regenerative power. The first MG 14 and the second MG 15 are, for example, AC rotating electric machines. The AC rotating electric machine is, for example, a permanent magnet synchronous motor with a rotor in which a permanent magnet is embedded.

The first MG 14 and the second MG 15 are electrically connected to the battery 18 via the PCU 17. The PCU 17 charges the battery 18 using regenerative power generated in the first MG 14 or the second MG 15, and drives the first MG 14 or the second MG 15 using the power charged in the battery 18. The PCU 17 includes a first inverter that exchanges power with the first MG 14, a second inverter that exchanges power with the second MG 15, and a converter. The converter boosts the power of the battery 18 and supplies it to the first and second inverters, and reduces the power supplied from the first and second inverters and supplies it to the battery 18. The first inverter converts DC power from the converter to AC power and supplies it to the first MG 14, and converts AC power from the first MG 14 to DC power and supplies it to the converter. The second inverter converts DC power from the converter into AC power and supplies it to the second MG 15, and converts AC power from the second MG 15 into DC power and supplies it to the converter.

The battery 18 is composed of multiple stacked batteries. The batteries are, for example, secondary batteries such as nickel-metal hydride batteries or lithium-ion batteries.

The power split mechanism 20 is, for example, a planetary gear mechanism including a sun gear, a planetary carrier, a pinion gear, and a ring gear. The crankshaft 27 of the engine 10 is connected to the power split mechanism 20 via a torsional damper 19. The power split mechanism 20 mechanically connects the crankshaft 27 of the engine 10, the rotating shaft of the first MG 14, and the output shaft of the power split mechanism 20.

The reduction mechanism 22 is a multi-stage automatic transmission that changes the gear ratio. Under the control of the ECU 50, the reduction mechanism 22 changes the gear ratio and switches between multiple power transmission states. The multiple power transmission states include N (neutral) range, D (drive) range, R (reverse) range, and P (parking) range. A continuously variable transmission (CVT) that continuously changes the gear ratio may be used instead of the reduction mechanism 22.

The output shaft of the power split mechanism 20 is connected to the reduction mechanism 22. The rotating shaft of the second MG 15 is also connected to the reduction mechanism 22. The reduction mechanism 22 is connected to the differential gear 24. The differential gear 24 is connected to a drive shaft 25. Drive wheels 26 are attached to the ends of the drive shafts 25.

The engine 10, first MG 14, and second MG 15 function as drive sources that generate drive force. The drive force of the engine 10, first MG 14, and second MG 15 is transmitted to the drive wheels 26 via the reduction gear mechanism 22 and the differential gear 24.

The ECU 50 is a control device for the vehicle 1, and includes an arithmetic unit such as a CPU (Central Processing Unit), and storage devices such as RAM (Random Access Memory) and ROM (Read Only Memory). The ECU 50 performs various controls by executing programs stored in the ROM and storage devices. The ECU 50 acquires the engine 10 rotation speed detected by the rotation speed sensor 29. The ECU 50 controls the engine 10, first MG 14, second MG 15, PCU 17, and battery 18. The ECU 50 functions as a start control unit and a vibration damping control unit. The start control unit performs start processing for the engine 10. The vibration damping control unit performs vibration damping control.

When the engine 10 rotates, the torque generated by the engine 10 is transmitted to the torsional damper 19, power split mechanism 20, reduction gear mechanism 22, drive shaft 25, etc. The transmission of torque may cause vibrations in the vehicle 1. For example, during the start-up process of the engine 10, the ECU 50 performs vibration suppression control to control vibrations using the first MG 14 and the second MG 15. Vibration suppression control using both the torque of the first MG 14 and the torque of the second MG 15 is called cooperative vibration suppression control. In cooperative vibration suppression control, the torque output by the first MG 14 and the second MG 15 is torque (reverse torque) in the opposite direction to the rotational direction of the engine 10.

The engine 10 is started by rotating it with the torque output by at least one of the first MG 14 and the second MG 15 (start process). In the start process, the torque of both the first MG 14 and the second MG 15 may be used. Alternatively, only the torque output by the first MG 14 may be used. Alternatively, only the torque output by the second MG 15 may be used. In this embodiment, the torque of the first MG 14 is used. The torque output by the first MG 14 in the start process is torque in the same direction as the rotation direction of the engine 10 (forward torque).

Figure 2 is a flowchart illustrating the control executed by the ECU 50. The ECU 50 determines whether the engine 10 is in the process of starting (step S10). If the determination is negative (No), the ECU 50 disables cooperative vibration suppression control (step S18). Cooperative vibration suppression control is not executed.

If the determination in step S10 is affirmative (Yes), the ECU 50 determines whether the conditions for cooperative vibration suppression control are met (step S12). If the determination is negative, the ECU 50 does not permit cooperative vibration suppression control (step S18). For example, when the engine 10 rotation speed is increasing (the rate of change in rotation speed is positive), it is determined that the conditions are met (affirmative determination).

After a positive determination is made in step S12, the ECU 50 determines whether the duration of the engine 10 start process is equal to or longer than a predetermined time (step S14). If a negative determination is made in step S14, the ECU 50 permits cooperative vibration suppression control (step S16). Cooperative vibration suppression control is performed. If a positive determination is made in step S14, the ECU 50 prohibits cooperative vibration suppression control (step S18). Cooperative vibration suppression control is stopped. The torque of the first MG 14 is used in the engine 10 start process. This completes the processing in Figure 2.

Figure 3 is a diagram illustrating an example of a time chart. The first row from the top of Figure 3 represents the engine 10 mode. The second row represents the engine 10 rotation speed. The third row represents the cooperative vibration suppression control permission flag.

As shown in Figure 3, the engine 10 is stopped from time 0 to time t1. The rotation speed is zero. Cooperative vibration suppression control is not performed. At time t1, the engine 10 start process begins. The engine 10 rotation speed increases. Cooperative vibration suppression control is permitted and performed.

In the example shown by the dashed lines in Figure 3, the rotation speed increases over time. The start-up process ends at time t2. The engine 10 operates. Cooperative vibration suppression control is disabled and stopped. On the other hand, in the example shown by the solid lines in Figure 3, the start-up process continues after time t2. Cooperative vibration suppression control also continues. At time t3, cooperative vibration suppression control is disabled and stopped. The first MG 14 and the second MG 15 stop outputting reverse torque. The forward torque output by the first MG 14 is used to start the engine 10.

According to this embodiment, the ECU 50 performs the start process for the engine 10 and also performs cooperative vibration suppression control. For example, the torque output by the first MG 14 is used in the start process. The torque output by the first MG 14 and the torque output by the second MG 15 are used in the cooperative vibration suppression control. If the duration of the start process is equal to or longer than a predetermined time, the ECU 50 stops the cooperative vibration suppression control (step S18 in Figure 2). After the cooperative vibration suppression control is stopped, the torque of the first MG 14 that was used in the cooperative vibration suppression control is used to start the engine 10. This improves the startability of the engine 10.

The torque (forward torque) output by the first MG 14 is used in the start-up process. The torque (reverse torque) output by the first MG 14 is used in the cooperative vibration suppression control. During the start-up process and cooperative vibration suppression control, the torque output by the first MG 14 includes forward torque and reverse torque. After cooperative vibration suppression control is stopped, the ECU 50 reduces the reverse torque of the first MG 14 and increases the forward torque. Since the torque used in the start-up process of the engine 10 is increased, startability is improved.

The torque output by the second MG 15 may be used in the startup process. After cooperative vibration suppression control is stopped, the second MG 15 reduces the reverse torque and increases the forward torque. The forward torque output by both the first MG 14 and the second MG 15 may be used in the startup process. The threshold (predetermined time) for the duration of the startup process is, for example, several seconds, and may be determined depending on the vehicle model, etc.

Although the preferred embodiment of the present invention has been described in detail above, the present invention is not limited to such specific embodiment, and various modifications and variations are possible within the scope of the gist of the present invention as set forth in the claims.

1 Vehicle 10 Engine 14 First motor generator 15 Second motor generator 17 PCU
18 Battery 19 Torsional damper 20 Power split mechanism 22 Reduction mechanism 24 Differential gear 25 Drive shaft 26 Drive wheels 27 Crankshaft 29 Revolution speed sensor 50 ECU

Claims (3)

A control device for a vehicle including an internal combustion engine, a first electric motor, and a second electric motor,
a start control unit that performs a start process of the internal combustion engine using both the first electric motor and the second electric motor or a torque output by the first electric motor ;
a vibration damping control unit that performs vibration damping control, which is vibration control using the first electric motor and the second electric motor,
In the start-up process, both of the first electric motor and the second electric motor or the first electric motor outputs torque in the same direction as a rotation direction of the internal combustion engine,
During the vibration damping control, the first electric motor and the second electric motor output torque in a direction opposite to a rotation direction of the internal combustion engine,
When the startup control unit performs the startup process, the vibration damping control unit performs the vibration damping control,
When the internal combustion engine is started by the start processing of the internal combustion engine, the start control unit ends the start processing, and the vibration damping control unit stops the vibration damping control,
A vehicle control device in which, when the duration of the start-up process of the internal combustion engine is equal to or longer than a predetermined time, the vibration damping control unit stops the vibration damping control, and after the vibration damping control is stopped, the start-up control unit reduces the torque output by the first electric motor and the second electric motor in the direction opposite to the rotational direction of the internal combustion engine to zero, and increases the torque output by both the first electric motor and the second electric motor or the first electric motor in the same direction as the rotational direction to a level greater than during the vibration damping control, and continues the start-up process . A vehicle control device as described in claim 1, wherein the start control unit performs start processing of the internal combustion engine using only the torque output by the first electric motor. The vehicle control device according to claim 1 , wherein the start control unit performs a start process for the internal combustion engine using the torque output by the first electric motor and the torque output by the second electric motor.