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US-20260125046-A1 - HYBRID VEHICLE

US20260125046A1US 20260125046 A1US20260125046 A1US 20260125046A1US-20260125046-A1

Abstract

In a hybrid vehicle having a driving mode including a motor mode in which the engine is controlled to a stopped state and a hybrid mode in which the engine is controlled to an operating state, when the remaining amount of fuel falls below a lower limit value, a control system of the hybrid vehicle starts a drive-sustaining control that prohibits the hybrid mode and executes the motor mode. During execution of the drive-sustaining control, when an SOC of an energy storage device decreases to a drive-termination threshold, the control system sets a drive-disable flag and terminates the drive-sustaining control. Under a state where the drive-disable flag is set and the remaining amount of fuel exceeds the lower limit value by refueling, when a driver who drives the hybrid vehicle performs a start operation at the beginning of driving, the engine is started to start the hybrid mode.

Inventors

  • Shuichi Honda

Assignees

  • Subaru Corporation

Dates

Publication Date
20260507
Application Date
20251021
Priority Date
20241101

Claims (5)

  1. 1 . A hybrid vehicle comprising an engine and a motor generator, the hybrid vehicle further comprising: a fuel tank coupled to the engine via a fuel pipe; an energy storage device coupled to the motor generator via a power cable; and a control system comprising a processor and a memory communicably coupled to each other, and configured to control the engine and the motor generator, wherein a driving mode includes a motor mode in which the engine is controlled to a stopped state and a hybrid mode in which the engine is controlled to an operating state, wherein, when the remaining amount of fuel in the fuel tank falls below a lower limit value, the control system is configured to start a drive-sustaining control configured to prohibit the hybrid mode and execute the motor mode, wherein, during execution of the drive-sustaining control, when an SOC of the energy storage device decreases to a drive-termination threshold, the control system is configured to set a drive-disable flag and terminate the drive-sustaining control, and wherein, under a state where the drive-disable flag is set and the remaining amount of fuel exceeds the lower limit value by refueling, when a driver who drives the hybrid vehicle performs a start operation at the beginning of driving, the engine is started to start the hybrid mode.
  2. 2 . The hybrid vehicle according to claim 1 , wherein the control system is configured to cause the motor generator to perform a starting rotation of the engine.
  3. 3 . The hybrid vehicle according to claim 1 , wherein, under a state where the drive-disable flag is not set, when the driver performs the start operation at the beginning of driving, the control system is configured to start the motor mode without starting the engine.
  4. 4 . The hybrid vehicle according to claim 1 , wherein, under a state where the drive-disable flag is set and the remaining amount of fuel exceeds the lower limit value by refueling, when the driver performs the start operation at the beginning of driving, the control system is configured to start the engine to start the hybrid mode and cause the motor generator to perform a regeneration drive by the engine.
  5. 5 . The hybrid vehicle according to claim 1 , wherein, under a state where the drive-disable flag is set and the remaining amount of fuel exceeds a remaining fuel threshold by refueling, when the driver performs the start operation at the beginning of driving, the control system is configured to start the engine to start the hybrid mode, wherein the remaining fuel threshold is greater than the lower limit value.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS The present application claims priority from Japanese Patent Application No. 2024-192942 filed on November 1, 2024, the entire contents of which are hereby incorporated by reference. BACKGROUND The disclosure relates to a hybrid vehicle. Hybrid vehicles equipped with an engine and a motor generator have been developed (see Japanese Unexamined Patent Application Publication (JP-A) Nos. 2008-201170, 2013-147057, and 2009-12593). An example of the driving mode for such a hybrid vehicle includes a motor mode in which the engine is controlled to a stopped state, and a hybrid mode in which the engine is controlled to an operating state. However, under a state where the hybrid mode is being executed, when the remaining amount of fuel in a fuel tank falls below a lower limit value, the driving mode is switched from the hybrid mode to the motor mode. Additionally, the motor mode executed after fuel depletion is continued until driving of the motor generator becomes difficult, that is, until a state of charge (SOC) of a battery falls below a predetermined drive-termination threshold value. From the viewpoint of extending travel distance in the motor mode executed after fuel depletion, it is desirable to lower the drive-termination threshold value which is a termination condition of the motor mode. SUMMARY An aspect of the disclosure provides a hybrid vehicle comprising an engine and a motor generator. The hybrid vehicle further comprises a fuel tank coupled to the engine via a fuel pipe, an energy storage device coupled to the motor generator via a power cable, and a control system configured to control the engine and the motor generator and comprising a processor and a memory communicably coupled to each other. A driving mode includes a motor mode in which the engine is controlled to a stopped state and a hybrid mode in which the engine is controlled to an operating state. When the remaining amount of fuel in the fuel tank falls below a lower limit value, the control system is configured to start a drive-sustaining control configured to prohibit the hybrid mode and execute the motor mode. During execution of the drive-sustaining control, when an SOC of the energy storage device decreases to a drive-termination threshold, the control system is configured to set a drive-disable flag and terminate the drive-sustaining control. Under a state where the drive-disable flag is set and the remaining amount of fuel exceeds the lower limit value by refueling, when a driver who drives the hybrid vehicle performs a start operation at the beginning of driving, the engine is started to start the hybrid mode. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram illustrating a hybrid vehicle according to one embodiment of the disclosure. FIG. 2 is a diagram illustrating an example of a power unit. FIG. 3 is a diagram illustrating an example of a control system configured to control a power unit. FIG. 4 is a diagram illustrating an example of basic structures of electronic controllers. FIG. 5 is a map illustrating an example of an execution region for a driving mode. FIG. 6 is a flowchart illustrating an example of an execution procedure for a drive-sustaining control. FIG. 7 is a flowchart illustrating an example of an engine-start procedure after refueling. FIG. 8 is a timing chart illustrating an example of an execution status of the drive-sustaining control and engine-start. DETAILED DESCRIPTION Hereinafter, an embodiment of the disclosure will be described in detail with reference to drawings. In the following descriptions, the same or substantially same components and elements are denoted by the same reference signs and repetitive descriptions are omitted. Power Unit FIG. 1 is a diagram illustrating a hybrid vehicle 10 according to one embodiment of the disclosure. As illustrated in FIG. 1, the hybrid vehicle 10 comprises a power unit 12 having an engine 11 and motor generators MG1 and MG2. A rear wheel output shaft 13 of the power unit 12 is connected to one or more rear wheels 16 via a propeller shaft 14 and a rear differential mechanism 15. Additionally, the power unit 12 comprises a front differential mechanism 17. The front differential mechanism 17 is connected to one or more front wheels 18. The illustrated power unit 12 is a power unit for all-wheel drive, but the disclosure is not limited to this, and the power unit may be a unit for front-wheel drive or rear wheel-drive. FIG. 2 is a diagram illustrating an example of the power unit 12. As illustrated in FIG. 2, the power unit 12 comprises a main output shaft 20 passing through a center of the motor generator MG2. The main output shaft 20 is connected to a front wheel output shaft 22 via a gear train 21, and is also connected to the rear wheel output shaft 13 via a transfer clutch 2. Additionally, the main output shaft 20 is connected to a power splitting mechanism 25 via a gear train 24. The power splitting mechanism 25 is conn