Travel control device for hybrid vehicle

Abstract

This travel control device for a hybrid vehicle includes: a storage unit that stores a map in which an engine travel region where an engine travel mode is selected and an EV travel region where an EV travel mode is selected are associated with vehicle speeds and target torques; a selection unit that selects either the EV travel mode or the engine travel mode according to whether the vehicle speed and the target torque are included in the EV travel region or are included in the engine travel region; and a region change unit that changes the sizes of the engine travel region and the EV travel region according to the height of a water surface.

Description

Hybrid vehicle driving control device

[0001] The present disclosure relates to a driving control device for a hybrid vehicle.

[0002] Hybrid vehicles are widely known that have an EV driving mode in which the engine is stopped and the drive motor drives the drive wheels using electricity stored in the drive battery to propel the vehicle (see, for example, Patent Document 1).

[0003] Japanese Patent Application Publication No. 9-156382

[0004] However, since there is a high risk of engine damage if the engine takes in water, hybrid vehicles may operate in EV driving mode if the engine is submerged. Therefore, if a hybrid vehicle is submerged in water, it is required to store electricity in the drive battery in case the engine is submerged.

[0005] In view of the above circumstances, at least one embodiment of the present invention aims to provide a driving control device for a hybrid vehicle that can store electricity in a drive battery in preparation for the engine being submerged in water.

[0006] (1) In at least one embodiment of the present invention, a hybrid vehicle cruise control device includes an engine, a generator driven by the engine, a drive battery that stores electricity generated by the generator, a drive motor that drives drive wheels using electricity supplied from the generator or the drive battery, and a detection device that detects the height of the water surface around a vehicle submerged in water. The hybrid vehicle cruise control device is capable of selecting between an EV driving mode in which the engine is stopped and the vehicle is driven by the drive motor, and an engine driving mode in which the vehicle is driven by the engine. The hybrid vehicle cruise control device includes: a memory unit that stores a map in which an engine driving range in which the engine driving mode is selected and an EV driving range in which the EV driving mode is selected are associated with vehicle speed and target torque; a selection unit that selects either the EV driving mode or the engine driving mode depending on whether the vehicle speed and the target torque are included in the EV driving range or the engine driving range; and a region change unit that changes the size of the engine driving range and the EV driving range depending on the height of the water surface.

[0007] According to the configuration (1) above, the size of the engine driving range and the EV driving range are changed depending on the height of the water surface, so that electricity can be stored in the drive battery in preparation for the engine being submerged.

[0008] (2) In some embodiments, in the configuration of (1) above, when the water surface height is equal to or greater than a predetermined first threshold, the area change unit expands the engine driving area in the map and reduces the EV driving area.

[0009] According to the configuration (2) above, when the water level is equal to or higher than the first threshold, the engine driving range is expanded and the EV driving range is reduced, making it easier to select the engine driving mode than the EV driving mode. This reduces the consumption of electricity stored in the drive battery, allowing electricity to be stored in the drive battery in preparation for the engine being submerged.

[0010] (3) In some embodiments, in the configuration of (2) above, the engine driving range includes a series driving range in which a series driving mode is selected in which the generator is driven by the engine while the vehicle is driven by the drive motor, and the range change unit changes the EV driving range to the series driving range when the height of the water surface is equal to or greater than a second threshold value that is predetermined higher than the first threshold value.

[0011] According to the configuration (3) above, when the water level is equal to or higher than the second threshold, the EV driving range is changed to the series driving range, so that the EV driving mode is no longer selected and the series driving mode is selected. This reduces the consumption of electricity stored in the drive battery, allowing more electricity to be stored in the drive battery in preparation for the engine being submerged.

[0012] (4) In some embodiments, in the configuration of (3) above, when the water level is equal to or greater than the second threshold and less than a third threshold that is predetermined to be higher than the second threshold, the driving control device increases the target charge amount of the drive battery as the water level increases.

[0013] According to the configuration (4) above, when the water level is equal to or greater than the second threshold and less than the third threshold, the target charge amount of the drive battery increases as the water level increases, so that electricity generated by the generator can be stored in the drive battery in preparation for the engine being submerged.

[0014] (5) In some embodiments, in the configuration of (3) above, the area change unit changes the engine driving area to the EV driving area when the height of the water surface is equal to or greater than a third threshold value that is predetermined higher than the second threshold value.

[0015] According to the configuration (5) above, when the water level is equal to or higher than the third threshold, the engine driving range is changed to the EV driving range, so that the engine driving mode is no longer selected and the EV driving mode is selected, thereby stopping the engine and preventing malfunctions caused by the engine ingesting water.

[0016] (6) In some embodiments, in the configuration of (5) above, when the water surface height is equal to or greater than the third threshold and the EV driving mode is selected by the selection unit, the selection unit selects the EV driving mode if the water surface height is less than the second threshold and equal to or greater than the first threshold, and when the water surface height is less than the first threshold, selects either the EV driving mode or the engine driving mode based on the map.

[0017] According to the configuration of (6) above, when the water level is equal to or higher than the third threshold and EV driving is selected, the EV driving mode is selected if the water level is lower than the second threshold and equal to or higher than the first threshold, so the engine will not start if the water level is equal to or higher than the first threshold, thereby preventing malfunctions caused by the engine ingesting water.

[0018] (7) In some embodiments, in the configuration of (6) above, the selection unit selects the EV driving mode when the longitudinal angle of the hybrid vehicle is equal to or greater than a predetermined first angle, which causes the front of the hybrid vehicle to rise upward relative to the horizontal plane, even if the height of the water surface is lower than the first threshold value.

[0019] According to the configuration of (7) above, even if the water level is lower than the first threshold, the EV mode is selected when the hybrid vehicle is tilted forward from the horizontal plane at a predetermined first angle or more, so that even if the engine is not submerged, starting of the engine can be prohibited when the muffler is submerged, thereby preventing water from entering the muffler.

[0020] According to at least one embodiment of the present invention, electricity can be stored in the drive battery in preparation for the engine being submerged in water.

[0021] 1 is a schematic diagram showing the mechanical configuration of a hybrid vehicle according to embodiment 1. FIG. 2 is a block diagram showing the control configuration of the hybrid vehicle according to embodiment 1. FIG. 3 is a diagram showing the relative positions of the water surface and the hybrid vehicle. FIG. 4 is a diagram showing a map in which an EV driving range and an engine driving range are associated with vehicle speed and target torque. FIG. 5 is a diagram showing a map in which the EV driving range and the engine driving range are changed when the relative position of the water surface exceeds a first threshold. FIG. 6 is a diagram showing a map in which the EV driving range is changed to a series driving range when the relative position of the water surface exceeds a first threshold and is less than a second threshold. FIG. 7 is a diagram showing a map in which the series driving range is changed to an EV driving range when the relative position of the water surface exceeds a second threshold. FIG. 8 is a diagram showing the relationship between the height of the water surface and the target charge amount. FIG. 9 is a diagram showing a control flow for a hybrid vehicle according to embodiment 1. FIG. 10 is a diagram showing the height of the water surface relative to a vehicle submerged in water and the position of the exhaust pipe of the vehicle, which is tilted forward. FIG. 11 is a diagram showing a control flow for a hybrid vehicle according to embodiment 3.

[0022] Hereinafter, several embodiments of the present invention will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of components described as embodiments or shown in the drawings are merely illustrative examples and are not intended to limit the scope of the present invention.

[0023] [Embodiment 1] [Hybrid Vehicle] A hybrid vehicle according to embodiment 1 is a plug-in hybrid vehicle (PHV, PHEV) that can be charged (externally charged) from an external device (e.g., a quick charger) while the vehicle is stopped, and can supply power (externally to a general household) while the vehicle is stopped, but is not limited to this. The hybrid vehicle according to embodiment 1 is a hybrid vehicle with two front wheel drive, but may also be a hybrid vehicle with four wheel drive.

[0024] [Mechanical Configuration of Hybrid Vehicle] Fig. 1 is a diagram that schematically shows the mechanical configuration of a hybrid vehicle 1A according to embodiment 1. As shown in Fig. 1, the hybrid vehicle 1A according to embodiment 1 includes an engine 11, a generator 12 driven by the engine 11, a drive battery 13 that stores electricity generated by the generator 12, and a drive motor 15 that drives drive wheels 14 with electricity supplied from the generator 12 or the drive battery 13.

[0025] The engine 11, generator 12, and drive motor 15 are fixed to a transaxle 16. Power from the engine 11 is transmitted to the generator 12 via the transaxle 16, and power from the drive motor 15 is transmitted to drive wheels 14 (axles 17) via the transaxle 16. A fuel pipe 18 is connected to the engine 11, and fuel is supplied from a fuel tank 19. The generator 12 and drive motor 15 are electrically connected to a power drive unit (PDU) 20. The power drive unit 20 incorporates a generator control unit (GCU) and a motor control unit (MCU). The generator control unit controls the generator 12 and is configured to rectify electricity generated by the generator 12 from AC to DC. The motor control unit controls the drive motor 15 and is configured to convert electricity supplied from the drive battery 13 from DC to AC and convert electricity regenerated by the drive motor 15 from AC to DC. The hybrid vehicle 1A configured in this manner can select either an EV driving mode in which the engine 11 is stopped and the vehicle is driven by the drive motor 15, or an engine driving mode in which the vehicle is driven by the engine 11. The engine driving mode includes a series driving mode in which electricity generated by driving the generator 12 with the engine 11 is supplied to the drive motor 15 or the drive battery 13, and the drive wheels 14 are driven by the drive motor 15.

[0026] [Control Configuration of Hybrid Vehicle] Figure 2 is a block diagram that shows a schematic control configuration of the hybrid vehicle 1A according to embodiment 1. As shown in Figure 2, the hybrid vehicle 1A according to embodiment 1 includes, in addition to the power drive unit 20 described above, a battery management unit (BMU) 21 that manages the drive battery 13, an engine control unit (engine ECU) 22 that controls the engine 11, and a driving control unit (HEV-ECU) 23A that controls these.

[0027] The power drive unit 20, the battery management device 21, the engine control device 22, and the driving control device 23A are connected via a CAN 25, and each device transmits and receives information.

[0028] The battery management device 21, the engine control device 22, and the driving control device 23A are each composed of a processor consisting of an arithmetic unit, a register for storing instructions and information, and peripheral devices, memories such as ROM (Read Only Memory) and RAM (Random Access Memory), and an input interface.

[0029] The cruise control device 23A is connected to a wheel speed sensor 26 that detects the wheel speed, and an accelerator position sensor 28 that detects the depression amount (accelerator opening) of an accelerator pedal 27. The cruise control device 23A calculates the vehicle speed from the information from the wheel speed sensor 26 and the target torque (required torque) from the information from the accelerator position sensor 28.

[0030] The driving control device 23A is provided with a control unit 29 that controls the power drive unit 20, the battery management device 21, and the engine control device 22, as well as a memory unit 30 that stores a map in which the EV driving range and the engine driving range are associated with the vehicle speed and the target torque, and a selection unit 31 that selects the EV driving mode when the vehicle speed and the target torque are within the EV driving range, and selects the engine driving mode when the vehicle speed and the target torque are within the engine driving range.

[0031] [Map] Figure 4 is a diagram showing a map in which an EV driving range ArEV and an engine driving range ArEN are associated with vehicle speed and target torque. The EV driving range ArEV is set to a range in which drive motor 15 can output power using the output power of drive battery 13, and the engine driving range ArEN is set to a range in which drive motor 15 can output power using the output power of drive battery 13 and generator 12. As shown in Figure 4, the EV driving range ArEV and the engine driving range ArEN do not exist independently but are separated by a boundary line BD, and the range with a smaller product of vehicle speed and target torque (vehicle speed x target torque) is the EV driving range ArEV, and the range with a larger product is the engine driving range ArEN.

[0032] 2, the hybrid vehicle 1A according to the first embodiment includes a detection device 32 that detects the height of the water surface around the hybrid vehicle 1A, i.e., the relative position of the water surface with respect to the submerged hybrid vehicle 1A. The detection device 32 is, for example, a level sensor such as a float switch or a distance sensor such as a radar, but is not limited thereto.

[0033] [Area change unit] As shown in Figure 2, the driving control device 23A of embodiment 1 is equipped with an area change unit 33 that changes the size of the EV driving area ArEV and the engine driving area ArEN, i.e., the position of the boundary line BD, depending on the height of the water surface.

[0034] In the first embodiment, the cruise control device 23A stores a first threshold value LV1, and the region changing unit 33 reduces the EV driving region ArEV and expands the engine driving region ArEN as the water level increases, as shown in FIG. 5 . That is, the region changing unit 33 moves the position of the boundary line BD toward the side where the product of the vehicle speed and the target torque decreases. The higher the water level, the greater the possibility that the engine 11 will be submerged in the future, and the greater the possibility that the vehicle will be forced to operate in EV driving mode, in which the engine 11 is stopped. Therefore, by making the engine driving mode more likely to be selected until the possibility of the engine 11 being submerged increases, electricity is stored in the drive battery 13, and a following distance in EV driving mode is ensured in the event that the engine 11 is submerged and the vehicle is forced to operate in EV driving mode.

[0035] In the first embodiment, when the water surface height becomes equal to or greater than the first threshold value LV1, the area change unit 33 changes the map stored in the storage unit 30 (the map shown in FIG. 4 ) to a map (the map shown in FIG. 5 ) in which the EV driving area ArEV is smaller than when the water surface height is less than the first threshold value, thereby reducing the EV driving area ArEV and expanding the engine driving area ArEN compared to when the water surface height is less than the first threshold value. However, the change in the sizes of the EV driving area ArEV and the engine driving area ArEN is not limited to this, and the position of the boundary line BD may be continuously moved toward a side where the product of the vehicle speed and the target torque is smaller as the water surface height increases.

[0036] The first threshold value LV1 may be set to a height that is low enough to prevent the engine 11 from being submerged, but is still relatively high (if the water level is higher than this, the engine 11 may be submerged). FIG. 3 is a diagram showing the relative positions of the water surface and the hybrid vehicle 1A (engine 11). As shown in FIG. 3, the first threshold value LV1 is set to a position that is above the lower end and below the upper end of the engine 11. In the first embodiment, the first threshold value LV1 is set to a height lower than the middle of the engine 11 in the height direction, but the present invention is not limited to this.

[0037] In the first embodiment, the region changing unit 33 reduces the EV driving region ArEV and expands the engine driving region ArEN as the water level increases. However, the region changing unit 33 may expand the EV driving region ArEV and contract the engine driving region ArEN as the water level increases. That is, the higher the likelihood of the engine 11 being submerged, the more likely the EV driving mode is selected, thereby preventing the engine 11 from suctioning water. However, in this case, it is highly likely that the vehicle will be traveling in the EV driving mode even when the water level is not that high (approximately a second threshold value LV2, described later). Therefore, it is possible that the drive battery 13 will not be able to store enough electricity when the engine 11 is submerged (approximately a third threshold value LV3, described later) and the EV driving mode is selected.

[0038] [Embodiment 2] [Mechanical Configuration of Hybrid Vehicle] The mechanical configuration of hybrid vehicle 1B according to embodiment 2 is the same as the mechanical configuration of hybrid vehicle 1A according to embodiment 1. In embodiment 2, the map used when the water surface height is equal to or greater than first threshold value LV1 is different from that in embodiment 1.

[0039] [Control Configuration of Hybrid Vehicle] In the second embodiment, when the water surface height is equal to or greater than a first threshold value LV1, the region changing unit 33 changes the EV driving region ArEV to the engine driving region ArEN as shown in FIG. 6 , i.e., the EV driving region ArEV is reduced to zero. The series driving mode is always selected in the engine driving region ArEN. Furthermore, when the water surface height is equal to or greater than a third threshold value LV3 (described later), the region changing unit 33 changes the engine driving region ArEN to the EV driving region ArEV as shown in FIG. 7 , i.e., the engine driving region ArEN is reduced to zero.

[0040] Furthermore, the driving control device 23B of the hybrid vehicle 1B according to the second embodiment changes the target charge amount of the drive battery 13 in the series driving mode according to the water level. Specifically, when the water level is equal to or higher than the first threshold value LV1, the higher the water level, the larger the target charge amount of the drive battery 13 is set.

[0041] [Water Surface Height and Target Charge Amount] As shown in FIG. 3 , the cruise control device 23B stores a second threshold value LV2 and a third threshold value LV3. The second threshold value LV2 is higher than the first threshold value LV1, and the third threshold value LV3 is higher than the second threshold value LV2. The third threshold value LV3 is a height at which the engine 11 is likely to be submerged. In the second embodiment, the third threshold value LV3 is set to a height above the middle of the engine 11 in the vertical direction. The second threshold value LV2 is a height at which the engine 11 is more likely to be submerged compared to the first threshold value LV1 and less likely to be submerged compared to the third threshold value LV3. In the second embodiment, the second threshold value LV2 is set to a height above the middle of the engine 11 in the vertical direction. FIG. 8 is a diagram showing the relationship between the water surface height and the target charge amount. As shown in FIG. 8 , the cruise control device 23B according to the second embodiment performs EV driving or engine driving so that the remaining battery charge of the drive battery 13 does not fall below a predetermined remaining battery charge (first charge amount SC1) until the water surface height becomes equal to or higher than the first threshold value LV1. When the water level exceeds the first threshold value LV1, and until it exceeds the second threshold value LV2, series driving is performed so that the charge level of the drive battery 13 is maintained at a predetermined second charge level SC2 that is higher than the first charge level SC1. As a result, when the water level exceeds the first threshold value LV1 and the possibility of the engine 11 being submerged increases, the series driving mode is selected, allowing the vehicle to drive while charging the drive battery 13, thereby storing more electricity in the drive battery 13.

[0042] When the water level exceeds the second threshold value LV2, the vehicle continues to drive in series driving mode so that the charge level of the drive battery 13 remains at a predetermined third charge level SC3, which is higher than the second charge level SC2, until the water level exceeds the third threshold value LV3. The map is not changed between the second threshold value LV2 and the third threshold value LV3. As the water level increases, the target charge level of the drive battery 13 increases, allowing electricity generated by the generator 12 to be stored in the drive battery 13 in preparation for the engine 11 being submerged.

[0043] In the series running mode, when the charge amount of the drive battery 13 is less than the target charge amount (first charge amount SC1 or second charge amount SC2), the output of the engine 11 is increased to increase the amount of power generated by the generator 12 and increase the charge amount of the drive battery 13. When the charge amount of the drive battery 13 reaches the target charge amount, the output of the engine 11 is adjusted so that the amount of power generated by the generator 12 is equal to the power consumption of the drive motor 15.

[0044] When the water level is equal to or higher than the third threshold LV3, the EV driving mode is activated. As a result, when there is a high possibility that the engine 11 will be submerged, the EV driving mode is activated, thereby preventing the engine 11 from absorbing water. Because the EV driving mode is always activated when the water level is equal to or higher than the third threshold LV3, a target charge amount is not set. Note that, once the water level is equal to or higher than the third threshold LV3 and the EV driving mode is activated, the EV driving mode continues until the water level falls below the first threshold LV1. Once the water level is equal to or higher than the third threshold LV3, it is possible that water remains in the intake pipe or exhaust pipe of the engine 11, which could cause water to enter the engine 11 when it is started. Therefore, the engine 11 is not started until the water level is sufficiently low and the water in the intake pipe or exhaust pipe of the engine 11 is drained.

[0045] The other control configurations are the same as those of the hybrid vehicle 1A according to the first embodiment.

[0046] [Control Operation of Cruise Control Device] Figure 9 shows the control flow of the hybrid vehicle 1B according to the second embodiment. The cruise control device 23B acquires the water level detected by the detector 32 (step S11). If the water level is less than the first threshold LV1 (step S12: No), the target charge amount of the drive battery 13 is set to a first charge amount SC1 (step S13). The selector 31 selects either the EV driving mode or the engine driving mode based on the charge amount of the drive battery 13 and the map stored in the memory 30 (step S14). Specifically, if the vehicle speed and target torque fall within the EV driving range ArEV, the EV driving mode is selected. If the vehicle speed and target torque fall within the engine driving range ArEN, the engine driving mode is selected. Furthermore, if the charge amount of the drive battery 13 reaches the first charge amount SC1 during the EV driving mode, the engine driving mode is selected regardless of the vehicle speed and target torque.

[0047] If the water level is equal to or greater than the first threshold value LV1 (step S12: Yes), the controller 31 determines whether the water level is equal to or greater than the second threshold value LV2 (step S15). If the water level is less than the second threshold value LV2 (step S15: No), the controller 31 sets the target charge amount of the drive battery 13 to the second charge amount SC2 (step S16), and the controller 31 selects the series traveling mode (step S17).

[0048] If the water level is equal to or greater than the second threshold value LV2 (step S15: Yes), the controller 31 determines whether the water level is equal to or greater than the third threshold value LV3 (step S18). If the water level is less than the third threshold value LV3 (step S18: No), the controller 31 sets the target charge amount of the drive battery 13 to a third charge amount SC3 (step S19), and the controller 31 selects the series traveling mode (step S20).

[0049] If the water level is equal to or higher than the third threshold LV3 (step S18: Yes), the selector 31 selects the EV driving mode (step S21). If the water level is then lower than the first threshold LV1 (step S22: Yes), the selector 31 selects either the EV driving mode or the engine driving mode based on the charge level of the drive battery 13 and the map stored in the memory 30 (step S23). If the water level is equal to or higher than the first threshold LV1 (step S22: No), the EV driving mode continues.

[0050] [Embodiment 3] [Mechanical Configuration of Hybrid Vehicle] The mechanical configuration of a hybrid vehicle 1C according to embodiment 3 is the same as the mechanical configuration of hybrid vehicle 1A according to embodiment 1, except that it has an angle sensor (not shown) that acquires the angle of the front-rear direction of hybrid vehicle 1C relative to the horizontal direction. The angle sensor is configured by, for example, an acceleration sensor.

[0051] [Control configuration of hybrid vehicle] The driving control device 23C of the hybrid vehicle 1C according to the third embodiment continues the EV driving mode even if the water surface height becomes equal to or greater than the third threshold value LV3 and the EV driving mode is selected by the selection unit 31, as long as the angle of the hybrid vehicle 1C relative to the horizontal direction is equal to or greater than the predetermined first angle θ and the front of the hybrid vehicle 1C is tilted backward (backward posture).

[0052] As shown in FIG. 10 , when the hybrid vehicle 1C is tilted backward, the height of the exhaust pipe outlet is lower than when the hybrid vehicle 1C is approximately parallel to the horizontal plane. Therefore, even if the water level is less than the first threshold LV1, the exhaust pipe outlet may still be submerged in water, and water may not be drained from the exhaust pipe. Therefore, the selection unit 31 continues the EV driving mode until the exhaust pipe outlet is out of water. Whether the exhaust pipe outlet is out of water may be determined, for example, by whether a predetermined time or a predetermined distance has been traveled since the water level is less than the first threshold LV1 and the angle of the hybrid vehicle 1C with respect to the horizontal direction becomes equal to or greater than the first angle θ. If it is determined that the exhaust pipe outlet is out of water, either the EV driving mode or the engine driving mode is selected based on the charge level of the drive battery 13 and the map stored in the memory unit 30.

[0053] The control flow of the hybrid vehicle 1C according to the third embodiment is shown in Fig. 11. The control flow of the third embodiment differs from the control flow of the second embodiment only from step S22 onwards. In Fig. 11, the same parts as those in the control flow of the second embodiment are denoted by the same reference numerals as in Fig. 9. Only the parts that differ from the control flow of the second embodiment will be described here.

[0054] [Control Operation of the Driving Control Device] After the water level becomes equal to or greater than the third threshold value LV3 in step S18 and the EV driving mode is selected in step S21, if the water level becomes less than the first threshold value LV1 (step S22: Yes), but the front-rising angle of the hybrid vehicle 1C with respect to the horizontal direction is equal to or greater than the first angle θ (step S31: Yes), the region change unit 33 does not change the map, and the selection unit 31 continues to select the EV driving mode. Thereafter, it is determined whether a predetermined time has elapsed (step S32). If the predetermined time has elapsed (step S32: Yes), the region change unit 33 switches the map to one in which the water level is less than the first threshold value LV1, and the selection unit 31 selects either the EV driving mode or the engine driving mode based on the charge amount of the drive battery 13 and the map stored in the memory unit 30.

[0055] If the water surface height is less than the first threshold value LV1 (step S22: Yes) and the front rising angle of the hybrid vehicle 1C with respect to the horizontal direction is less than the first angle θ (step S31: No), the region changing unit 33 switches the map to one with the water surface height less than the first threshold value LV1, and the selecting unit 31 selects either the EV driving mode or the engine driving mode based on the charge amount of the drive battery 13 and the map stored in the memory unit 30. If the front rising angle of the hybrid vehicle 1C with respect to the horizontal direction is equal to or greater than the first angle θ (step S31: Yes) and the predetermined time has not elapsed (step S32: No), the region changing unit 33 does not change the map and the selecting unit 31 continues to select the EV driving mode until the predetermined time has elapsed.

[0056] The present invention is not limited to the above-described embodiments, and includes modifications to the above-described embodiments and appropriate combinations of these modifications.

[0057] DESCRIPTION OF SYMBOLS 1A, 1B, 1C Hybrid vehicle 11 Engine 12 Generator 13 Drive battery 14 Drive wheels 15 Drive motor 16 Transaxle 17 Axle 18 Fuel pipe 19 Fuel tank 20 Power drive unit 21 Battery management unit (BMU) 22 Engine control unit (Engine ECU) 23A, 23B, 23C Driving control unit (HEV-ECU) 25 CAN 26 Wheel speed sensor 27 Accelerator pedal 28 Accelerator position sensor 29 Control unit 30 Memory unit 31 Selection unit 32 Detection device 33 Region change unit 34 Target charge amount change unit 35 Start inhibition unit ArEV EV driving region ArEN Engine driving region ArSR Series driving region BD Boundary line LV1 First threshold LV2 Second threshold LV3 Third threshold SC1 First charge amount (target charge amount) SC2 Second charge amount (target charge amount) SC3 Third charge amount (target charge amount)

Claims

1. A driving control device for a hybrid vehicle comprising: an engine; a generator driven by the engine; a drive battery that stores electricity generated by the generator; a drive motor that drives drive wheels with electricity supplied from the generator or the drive battery; and a detection device that detects the height of a water surface around a vehicle submerged in water, and capable of selecting an EV driving mode in which the engine is stopped and the vehicle is driven by the drive motor, and an engine driving mode in which the vehicle is driven by the engine, the driving control device comprising: a memory unit in which a map is stored in which an engine driving region in which the engine driving mode is selected and an EV driving region in which the EV driving mode is selected are associated with vehicle speed and target torque; a selection unit that selects either the EV driving mode or the engine driving mode depending on whether the vehicle speed and the target torque are included in the EV driving region or the engine driving region; and a region change unit that changes the size of the engine driving region and the EV driving region depending on the height of the water surface.

2. A driving control device for a hybrid vehicle as described in claim 1, wherein the area change unit expands the engine driving area and reduces the EV driving area in the map when the water surface height is equal to or higher than a predetermined first threshold value.

3. A driving control device for a hybrid vehicle as described in claim 2, wherein the engine driving range includes a series driving range in which a series driving mode is selected in which the generator is driven by the engine while the vehicle is driven by the drive motor, and the range change unit changes the EV driving range to the series driving range when the height of the water surface is equal to or greater than a second threshold value that is predetermined higher than the first threshold value.

4. A driving control device for a hybrid vehicle as described in claim 3, wherein when the water level is equal to or higher than the second threshold and less than a third threshold that is predetermined higher than the second threshold, the driving control device increases the target charge amount of the drive battery as the water level increases.

5. A driving control device for a hybrid vehicle as described in claim 3, wherein the area change unit changes the engine driving area to the EV driving area when the water surface height is equal to or greater than a third threshold value that is predetermined higher than the second threshold value.

6. A driving control device for a hybrid vehicle as described in claim 5, wherein when the water level is equal to or higher than the third threshold and the EV driving mode is selected by the selection unit, the selection unit selects the EV driving mode if the water level is less than the second threshold and equal to or higher than the first threshold, and selects either the EV driving mode or the engine driving mode based on the map if the water level is less than the first threshold.

7. A driving control device for a hybrid vehicle as described in claim 6, wherein the selection unit selects the EV driving mode when the longitudinal angle of the hybrid vehicle is equal to or greater than a predetermined first angle at which the front of the hybrid vehicle rises from the horizontal plane, even if the water surface height is lower than the first threshold value.

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