Hybrid vehicles

Abstract

To provide a hybrid vehicle which enables a rechargeable battery to be charged properly by regenerative power generation.SOLUTION: A vehicle 1 can switch its mode between a regenerative braking mode in which electric power is generated by a front motor 4 for travel drive to charge a drive battery 11 when the vehicle 1 travels while slowing down, a first motoring mode in which an engine 2 is forcibly driven by a motor generator 9 without supplying fuel to the engine 2, and a second motoring mode in which the engine 2 is forcibly driven by the motor generator 9 while the fuel is supplied to the engine 2 and burned. The first motoring mode is performed when a charging rate of the drive battery 11 is a first predetermined value or higher during the regenerative braking mode, and during the regenerative braking mode, the second motoring mode is performed when the charging rate of the drive battery 11 is lower than the first predetermined value and higher than or equal to a second predetermined value which is lower than the first predetermined value.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a control technique for regenerative power generation in a hybrid vehicle. [Background technology]

[0002] Among hybrid vehicles that have been developed in recent years, there is known a vehicle equipped with an internal combustion engine, a generator that is driven by the internal combustion engine to generate electricity, a drive battery (storage battery) that can be charged by receiving power from the generator, and a drive motor that is supplied with power from the drive battery or the generator to drive the driving wheels. In such hybrid vehicles, the electric power generated by the generator is supplied to the drive battery and the drive motor. When the vehicle decelerates, the drive motor generates regenerative power, and the generated power is supplied to the drive battery for charging. By generating regenerative power, the drive motor applies braking force to the vehicle (regenerative braking).

[0003] As described in Patent Document 1, if the drive battery is nearly fully charged during regenerative braking, the power generated by the drive motor cannot be charged into the drive battery. Therefore, a technology is known that enables regenerative braking by performing motoring, in which the engine is driven by, for example, a generator to consume power. Patent document 1 also discloses two types of motoring: motoring without firing, in which the engine is driven by a generator (motor-generator) without supplying fuel to it and combustion is stopped, and motoring with firing, in which the engine is driven by a generator while fuel is supplied to it and combustion is maintained. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2018-83573 Summary of the Invention [Problem to be solved by the invention]

[0005] In the above-mentioned Patent Document 1, when regenerative braking is performed with the drive battery charged at a predetermined level or more (near full charge), if motoring without firing continues for a predetermined period of time, control is exercised to switch to motoring with firing. Note that motoring with firing reduces engine friction compared to motoring without firing, and therefore reduces power consumption due to motoring.

[0006] However, if regenerative braking is performed while motoring without firing when the drive battery is charged above a certain level, motoring without firing may continue for a certain period of time and then switch to motoring with firing, which may result in a change in regenerative braking force. The present invention has been made to solve the above-mentioned problems, and its purpose is to provide a hybrid vehicle that can appropriately charge a storage battery using regenerative power generation while preventing motoring without firing from continuing for long periods of time. [Means for solving the problem]

[0007] In order to achieve the above object, the hybrid vehicle of the present invention is a hybrid vehicle having an internal combustion engine mounted on the vehicle, a first electric motor capable of driving the internal combustion engine, a second electric motor that drives the vehicle and is capable of generating regenerative electricity when the vehicle is decelerating, a storage battery that supplies power to the second electric motor, and a control unit that controls the operation of the first electric motor and the second electric motor, and is equipped with a charge amount detection unit that acquires the charge amount of the storage battery, and the control unit has a regenerative braking mode in which the second electric motor generates electricity and charges the storage battery to decelerate the vehicle, and a regenerative braking mode in which the first electric motor is driven without supplying fuel to the internal combustion engine The regenerative braking system is capable of switching between a first motoring mode in which the internal combustion engine is forcibly driven and the electric power generated by the second electric motor is consumed, and a second motoring mode in which the internal combustion engine is forcibly driven and the electric power generated by the second motor is consumed by supplying fuel to the internal combustion engine and burning it while driving the first electric motor, and is characterized in that the first motoring mode is implemented when the charge amount of the storage battery is equal to or greater than a first predetermined value during the regenerative braking mode, and the second motoring mode is implemented when the charge amount of the storage battery is less than the first predetermined value and equal to or greater than a second predetermined value that is smaller than the first predetermined value during the regenerative braking mode.

[0008] As a result, when the charge amount of the storage battery is equal to or greater than a first predetermined value in regenerative braking mode, a first motoring mode is implemented in which fuel is not supplied, thereby increasing friction in the internal combustion engine and causing the first electric motor to consume more power, thereby ensuring a large regenerative braking force.Furthermore, when the charge amount of the storage battery is less than the first predetermined value and equal to or greater than a second predetermined value in regenerative braking mode, a second motoring mode is implemented in which fuel is supplied, thereby ensuring a large regenerative braking force while preventing the charge amount of the storage battery from exceeding the first predetermined value.

[0009] Preferably, the vehicle includes a gradient acquisition unit that acquires the gradient of the road surface on which the vehicle is traveling, and the control unit changes the first predetermined value and the second predetermined value based on the gradient of the road surface during the regenerative braking mode. This allows the first and second predetermined values ​​to be changed in accordance with the generated power, which changes depending on the gradient of the road surface during regenerative braking mode, thereby more effectively ensuring regenerative braking force while preventing the storage battery from becoming nearly fully charged.

[0010] Preferably, the control unit sets the first predetermined value larger when the gradient of the road surface is an upward gradient than when it is on flat ground, and sets the first predetermined value smaller when the gradient of the road surface is a downward gradient than when it is on flat ground. As a result, when the road surface gradient is upward, the vehicle is more likely to decelerate and the storage battery is less likely to be fully charged, so by setting the first predetermined value larger, the number of times the first motoring mode is executed is reduced.When the road surface gradient is downward, the vehicle is more likely to decelerate and the storage battery is more likely to be fully charged, so by setting the first predetermined value smaller, the number of times the first motoring mode is executed is increased.As a result, in accordance with the road surface gradient, it is possible to prevent the first motoring mode from continuing for a long period of time and prevent the storage battery from becoming close to full charge, and to more effectively ensure regenerative braking force.

[0011] Preferably, the control unit switches to the second motoring mode when the first motoring mode has continued for a predetermined time. This prevents the first motoring mode from continuing beyond a predetermined time, and makes it possible to suppress oil leakage caused by forced rotation of the engine. Preferably, the control unit changes the predetermined time period in accordance with the rotation speed of the internal combustion engine in the first motoring mode.

[0012] This makes it possible to effectively suppress oil leakage in the first motoring mode. Preferably, the system includes an exhaust purification device provided in an exhaust passage of the internal combustion engine, an electric heater provided in the exhaust purification device, and a temperature acquisition means for acquiring the temperature of the exhaust purification device, and the control unit activates the electric heater when the temperature of the exhaust purification device is below a predetermined temperature, and when the first motoring mode is performed when the temperature of the exhaust purification device is below the predetermined temperature, increases the output of the electric heater compared to when the first motoring mode is not performed when the temperature is below the predetermined temperature.

[0013] As a result, when the temperature of the exhaust purification device is below a predetermined temperature and the first motoring mode is performed, the output of the electric heater is increased, which suppresses the temperature drop of the exhaust purification device and improves exhaust purification performance, and the power consumed by the electric heater prevents the storage battery from becoming fully charged. [Effects of the Invention]

[0014] According to the hybrid vehicle of the present invention, in the regenerative braking mode, the vehicle switches between a first motoring mode in which no combustion occurs and a large regenerative braking force can be secured, and a second motoring mode in which combustion occurs, depending on the charge level of the storage battery. This prevents the first motoring mode from continuing for a long period of time, while allowing the storage battery to be appropriately charged by regenerative power generation. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a schematic diagram of a hybrid vehicle according to an embodiment of the present invention; [Figure 2] 1 is a schematic diagram of an intake and exhaust system of an engine according to an embodiment of the present invention; [Figure 3] FIG. 4 is an explanatory diagram of motoring mode switching control. [Figure 4] 10 is an example of a map for setting a first predetermined time based on the engine rotation speed. [Figure 5] 10 is an example of a map for setting a first predetermined time based on a throttle opening degree. [Figure 6]4 is an example of a map for setting the output of an electric heater. [Figure 7] 10 is an example of a map for setting a second predetermined time based on the engine rotation speed. [Figure 8] 10 is an example of a map for setting a second predetermined time based on a throttle opening degree. DETAILED DESCRIPTION OF THE INVENTION

[0016] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an operation control device for a hybrid vehicle according to the present invention will now be described with reference to the accompanying drawings. FIG. 1 is a schematic diagram of a driving system of a hybrid vehicle (hereinafter referred to as vehicle 1) according to one embodiment of the present invention. In one embodiment of the present invention, the vehicle 1 is a vehicle such as a plug-in hybrid vehicle or hybrid vehicle that generates electricity by driving a motor generator 9 (first electric motor) using the output of an engine 2 (internal combustion engine) and is equipped with an electric front motor 4 (second electric motor) that drives the wheels.

[0017] The engine 2 is capable of driving a drive shaft 8 of the front wheels 3 via a front transaxle 7, and is also capable of driving a motor generator 9 via the front transaxle 7 to generate electricity. The engine 2 and the front wheels 3 are connected via a clutch 16 disposed within the front transaxle 7. The front motor 4 is powered by a drive battery 11 (storage battery) and a motor generator 9 mounted on the vehicle 1 via a control unit 20, and drives the drive shaft 8 of the front wheels 3 via a front transaxle 7.

[0018] The electric power generated by the motor generator 9 can charge the drive battery 11 and can also supply power to the front motor 4. The drive battery 11 is composed of a secondary battery such as a lithium ion battery. The drive battery 11 also includes a charge rate detector 11a (charge amount detector) that detects the state of charge (SOC) of the drive battery 11.

[0019] The control unit 20 (controller) has the function of controlling the driving mode, the output of the front motor 4, the power generation amount and output of the motor generator 9, the fuel injection amount and fuel injection timing of the engine 2, and the engagement and disengagement of the clutch 16 in the front transaxle 7. The driving modes include an EV driving mode, an engine driving mode, a parallel driving mode, and a series driving mode.

[0020] The control unit 20 is a control device for performing overall control of the vehicle 1. The control unit 20 includes an input / output device, a memory device (ROM, RAM, non-volatile RAM, etc.), a central processing unit (CPU), a timer, etc. In the EV mode, the engine 2 is stopped and the motor 46 is driven to run the vehicle. In series mode, the clutch 16 of the front transaxle 7 is disengaged, and the engine 2 drives the motor generator 9 to generate electricity, while driving the front motor 4 to drive the vehicle. In series mode, the rotational speed of the engine 2 is set to an efficient value.

[0021] In the parallel mode, the clutch 16 of the front transaxle 7 is connected, and the power of the engine 2 and the front motor 4 is transmitted to drive the front wheels 3. The control unit 20 sets the driving mode to parallel mode in a range where the engine 2 is efficient, such as a high-speed range. In a range other than parallel mode, i.e., a medium-to-low speed range, the control unit 20 switches between EV mode and series mode based on the state of charge (SOC) of the drive battery 11 (corresponding to the amount of charge).

[0022] 2 is a schematic diagram of the intake and exhaust system of the engine 2. The engine 2 is, for example, a multi-cylinder internal combustion engine. For simplicity, only one cylinder is shown in FIG. The engine 2 is configured so that fuel can be injected into the intake port 31 of each cylinder from a fuel injection valve 32 provided in the intake port 31 of each cylinder at any injection timing and injection amount, and can be ignited by an ignition plug 34.

[0023] An intake passage 33 of the engine 2 is provided with a throttle valve 30 for adjusting the flow rate of fresh air. An exhaust purification device 41, such as a three-way catalyst, is provided in an exhaust passage 40 of the engine 2. The exhaust purification device 41 is provided with an electric heater 42. Also, a temperature sensor 43 (temperature acquisition means) that detects the temperature of the exhaust purification device is provided.

[0024] A linear air-fuel ratio sensor (LAFS) 44 is provided in the exhaust passage 40 upstream of the exhaust purification device 41 and adjacent to the exhaust purification device 41. The LAFS 44 is used for feedback control of the fuel injection amount so that the detected value thereof becomes a value indicating a target air-fuel ratio, for example, a stoichiometric air-fuel ratio. The vehicle 1 is provided with a gradient acquisition unit 45 that acquires the gradient of the road on which the vehicle 1 is traveling. The gradient acquisition unit 45 may be, for example, an inclination angle sensor provided on the vehicle body, or may acquire the gradient from an external database or the like based on the vehicle's position information.

[0025] The control unit 20 calculates a target opening of the throttle valve 30 based on the target output torque of the engine 2 and controls the throttle valve 30 . In addition, the control unit 20 is capable of a regenerative braking mode in which, when the vehicle is decelerating, the front motor 4 is forcibly driven using the rotational force of the front wheels 3 to generate electricity (regenerative power generation), and regenerative braking is performed to apply braking force to the front wheels 3.

[0026] The regenerative braking force in the regenerative braking mode can be changed by selecting the gearshift lever. Furthermore, in the regenerative braking mode when the vehicle is decelerating, for example, when the charge rate of the drive battery 11 reaches or exceeds a predetermined value near full charge, the control unit 20 is capable of a motoring mode in which power is supplied to the motor generator 9 to operate it and rotate the engine 2.

[0027] In the motoring mode, power is consumed by driving the engine 2 with the motor generator 9. This ensures a regenerative braking force even when the charge rate of the drive battery 11 is close to full charge. In the motoring mode, the control unit 20 controls the engine rotation speed (motoring speed) by motoring by controlling the motor generator 9 in accordance with the state of charge (SOC) of the drive battery 11 and the amount of regenerative power generated by the front motor 4. For example, the amount of regenerative power generated by the front motor 4 may be input from the control unit 20.

[0028] Furthermore, in this embodiment, the motoring mode can be switched between a first motoring mode in which fuel injection is completely stopped and the engine 2 is driven to rotate by the motor generator 9, and a second motoring mode in which fuel injection is not completely stopped and combustion is maintained and the engine 2 is driven to rotate by the motor generator 9. The motoring mode control will be described in detail below.

[0029] FIG. 3 is an explanatory diagram of motoring mode switching control. For example, as shown in the flat road gradient of Figure 3, when regenerative braking is required (in regenerative braking mode), the control unit 20 executes a first motoring mode in which fuel injection is completely stopped if the state of charge SOC of the drive battery 11 is equal to or greater than a first predetermined value SOC1a (e.g., 90%) that is close to full charge (100%).

[0030] Furthermore, when regenerative braking is requested, if the state of charge (SOC) of the drive battery 11 is equal to or greater than a second predetermined value (SOC2a) (e.g., 80%) that is lower than the first predetermined value (SOC1a) and is less than the first predetermined value (SOC1a), the control unit 20 executes a second motoring mode in which fuel injection is suppressed to maintain combustion. In this embodiment, the second motoring mode causes the motor generator 9 to rotate the engine 2 in the same direction as the rotation during combustion (forward rotation). By driving the engine 2 at a higher speed by the motor generator 9 than the rotation due to combustion, the motor generator 9 consumes power.

[0031] If the state of charge SOC of the drive battery 11 is less than the second predetermined value SOC2a during the regenerative braking mode, the mode switches to the normal mode in which regenerative power generation is performed without motoring. In this manner, in this embodiment, when motoring is performed, the first motoring mode and the second motoring mode are switched based on the charging rate SOC of the driving battery 11.

[0032] As a result, in the regenerative braking mode, when the charge rate of the drive battery 11 is equal to or greater than a first predetermined value SOC1a that is close to full charge, the first motoring mode is executed to stop the supply of fuel to the engine 2, thereby increasing the friction of the engine 2, thereby consuming more power by forcibly driving the engine 2 with the motor generator 9, and ensuring a large regenerative braking force.

[0033] Furthermore, when the state of charge (SOC) of the drive battery 11 is equal to or greater than a second predetermined value (SOC2a) that is lower than the first predetermined value (SOC1a) but less than the first predetermined value (SOC1a), the second motoring mode is executed, which suppresses fuel supply to the engine 2 to maintain combustion, thereby ensuring regenerative braking force while preventing the state of charge of the drive battery 11 from exceeding the first predetermined value (SOC1a). This prevents the first motoring mode from continuing for a long period of time. Furthermore, by maintaining combustion in the second motoring mode, a decrease in exhaust temperature during the second motoring mode is suppressed, thereby maintaining the exhaust purification performance of the exhaust purification device 41. This makes it possible to ensure exhaust purification performance immediately after the start of acceleration when, for example, the accelerator is operated to accelerate from the second motoring mode.

[0034] Furthermore, the control unit 20 may change the first predetermined value SOC1 and the second predetermined value SOC2 based on the road gradient. For example, as shown in FIG. 3, when the road is on an uphill gradient, the first predetermined value SOC1b is set to a value greater than the first predetermined value SOC1a on flat ground, and the second predetermined value SOC2b is set to a value greater than the second predetermined value SOC2a on flat ground.

[0035] When the road is on a downward slope, the first predetermined value SOC1c is set to a value smaller than the first predetermined value SOC1a on flat ground, and the second predetermined value SOC2c is set to a value smaller than the second predetermined value SOC2a on flat ground. In this way, by changing the first predetermined value SOC1 and the second predetermined value SOC2 based on the generated power that changes depending on the gradient of the road surface during regenerative braking mode, it is possible to appropriately switch between the first motoring mode and the second motoring mode, thereby more effectively ensuring regenerative braking force while preventing the charging rate from becoming close to full charge.

[0036] In particular, on an uphill gradient where the vehicle 1 is more likely to decelerate and the required regenerative braking force is smaller, the driving battery 11 is less likely to reach full charge even if the number of opportunities to execute the first motoring mode is reduced. Therefore, the first predetermined value SOC1b is set larger than on flat ground. Also, on a downhill gradient where the vehicle 1 is less likely to decelerate and the required regenerative braking force is greater, the driving battery 11 is more likely to reach full charge. Therefore, the first predetermined value SOC1c is set smaller than on flat ground to increase the number of opportunities to execute the first motoring mode. Similarly, on an uphill gradient, the driving battery 11 is less likely to reach the first predetermined value SOC1 even if the number of opportunities to execute the second motoring mode is reduced. Therefore, the second predetermined value SOC2b is set larger than on flat ground, and starting of the engine 2 is suppressed. On a downhill gradient, the driving battery 11 is more likely to reach the first predetermined value SOC1. Therefore, the second predetermined value SOC2c is set smaller than on flat ground to increase the number of opportunities to execute the second motoring mode.

[0037] Furthermore, the control unit 20 not only switches between the first motoring mode and the second motoring mode depending on the charge rate of the drive battery 11 in the regenerative braking mode as described above, but also switches to the second motoring mode when the first motoring mode continues for a first predetermined time t1 (predetermined time). Fig. 4 shows an example of a map for setting the first predetermined time t1 based on the engine rotation speed. Fig. 5 shows an example of a map for setting the first predetermined time t1 based on the throttle opening.

[0038] The control unit 20 determines the final first predetermined time t1 by integrating the first predetermined time t1 calculated based on the engine rotation speed from a map such as that shown in FIG. 4 and the t1 coefficient calculated based on the throttle opening degree such as that shown in FIG. 5. As shown in Figure 4, the motoring time (first motoring time) is set to decrease by decreasing the first predetermined time t1 as the engine rotation speed (motoring speed) increases in the first motoring mode. Also, as shown in Figure 5, if the throttle opening decreases below the LAFS contamination lower limit opening M-min in the first motoring mode, the coefficient (t1 coefficient) is set to decrease as the throttle opening decreases. These correspond to the fact that oil rises up and becomes more likely to adhere to the LAFS 44 as the engine rotation speed increases or the throttle opening decreases below the LAFS contamination lower limit opening M-min in the first motoring mode.

[0039] In this way, by switching from the first motoring mode to the second motoring mode in response to a situation in which oil leakage or LAFS contamination is likely to occur in the first motoring mode, combustion in engine 2 can be started, thereby preventing oil leakage or LAFS contamination. An exhaust purification device 41 provided in an exhaust passage 40 of the engine 2 is equipped with an electric heater 42 and a temperature sensor 43 that detects the temperature of the exhaust purification device 41. As shown in Fig. 6, when the temperature (catalyst temperature) of the exhaust purification device 41 is equal to or lower than a predetermined temperature set near the lower limit of the activation temperature during engine operation, the control unit 20 activates the electric heater 42 to raise the temperature of the exhaust purification device 41, thereby improving the exhaust purification performance. Alternatively, the output of the electric heater 42 may be increased as the catalyst temperature decreases, so that the catalyst temperature quickly reaches the activation temperature.

[0040] Furthermore, when the temperature of the exhaust purification device 41 is below a predetermined temperature and the first motoring mode is performed, the control unit 20 may control the output of the electric heater 42 to be larger than when the temperature is below the predetermined temperature and the first motoring mode is not performed (when the engine is operating). When the first motoring mode, in which no combustion occurs, is performed, the exhaust temperature is low, resulting in a large temperature drop in the exhaust purification device 41. At this time, by increasing the output of the electric heater 42, it is possible to further suppress the temperature drop in the exhaust purification device 41 and improve exhaust purification performance. In addition, because the electric heater 42 can consume regenerative power, it is possible to ensure regenerative braking force.

[0041] Furthermore, as described above, when the engine 2 is motored in the first motoring mode, there is a possibility that oil may adhere to the spark plug 34 or the LAFS 44 due to oil rising, etc. Therefore, in this embodiment, the second motoring mode is executed until the second predetermined time t2 has elapsed since the completion of the first motoring mode, and then the mode is switched to the normal mode (fuel injection control based on the LAFS detection value).

[0042] Fig. 7 shows an example of a map for setting the second predetermined time t2 based on the engine rotation speed. Fig. 8 shows an example of a map for setting the second predetermined time t2 based on the throttle opening. The control unit 20 determines the final second predetermined time t2 by multiplying the second predetermined time t2 calculated based on the engine rotation speed using a map such as that shown in FIG. 7 by the t2 coefficient calculated based on the throttle opening degree such as that shown in FIG. 8.

[0043] As shown in Figure 7, the second motoring mode time after first motoring is set to increase as the engine rotation speed in first motoring mode increases. Also, as shown in Figure 8, if the throttle opening in first motoring mode falls below the LAFS contamination lower limit opening M-min and decreases, the t2 coefficient is set to increase as the throttle opening decreases. These correspond to the fact that as the engine rotation speed increases in first motoring mode or as the throttle opening falls below the LAFS contamination lower limit opening, oil rises and the LAFS 44 becomes more likely to adhere to it.

[0044] In this way, in situations where oil leakage or LAFS contamination is likely to occur during the first motoring mode, the second motoring mode is performed after the first motoring mode before transitioning to normal control, so that contamination of the LAFS 44, etc. can be reliably eliminated by firing before transitioning to normal mode. The present invention is not limited to the above-described embodiment, and for example, the details of the various controls described above may be changed as appropriate.

[0045] The present invention can be widely applied to hybrid vehicles capable of regenerative power generation and motoring. [Explanation of symbols]

[0046] 1 vehicle 2. Engine (internal combustion engine) 4 Front motor (second electric motor) 9 Motor generator (first electric motor) 11 Drive battery (storage battery) 11a Charging rate detection unit (charging amount detection unit) 20 Control unit (control section) 41 Exhaust gas purification device 42 Electric heater 43 Temperature sensor (temperature acquisition means) 45 Gradient acquisition unit

Claims

1. A hybrid vehicle having an internal combustion engine mounted on a vehicle, a first electric motor capable of driving the internal combustion engine, a second electric motor that drives the vehicle and is capable of regenerative power generation during deceleration, a storage battery that supplies power to the second electric motor, and a control unit that controls operation of the first electric motor and the second electric motor, a charge amount detection unit for acquiring a charge amount of the storage battery; The control unit a regenerative braking mode in which the second electric motor generates electricity to charge the storage battery, thereby decelerating the vehicle; a first motoring mode in which the internal combustion engine is forcibly driven by driving the first electric motor without supplying fuel to the internal combustion engine, thereby consuming electric power generated by the second electric motor; a second motoring mode in which fuel is supplied to the internal combustion engine and burned while the first electric motor is driven to forcibly drive the internal combustion engine and consume the electric power generated by the second electric motor; The first motoring mode is implemented when the charge amount of the storage battery is equal to or greater than a first predetermined value during the regenerative braking mode, and the second motoring mode is implemented when the charge amount of the storage battery is less than the first predetermined value and equal to or greater than a second predetermined value that is smaller than the first predetermined value during the regenerative braking mode. A hybrid vehicle characterized by:

2. a gradient acquisition unit that acquires a gradient of a road surface on which the vehicle is traveling; The control unit changes the first predetermined value and the second predetermined value based on the gradient of the road surface in the regenerative braking mode.

2. The hybrid vehicle according to claim 1.

3. The control unit When the gradient of the road surface is an uphill gradient, the first predetermined value is set to be larger than when the road surface is on a flat ground, When the gradient of the road surface is a downward gradient, the first predetermined value is set to be smaller than that on flat ground.

3. The hybrid vehicle according to claim 2.

4. The control unit switches the motoring mode to the second motoring mode when the first motoring mode continues for a predetermined time.

2. The hybrid vehicle according to claim 1.

5. The control unit changes the predetermined time period in accordance with the rotation speed of the internal combustion engine in the first motoring mode.

5. The hybrid vehicle according to claim 4.

6. an exhaust purification device provided in an exhaust passage of the internal combustion engine; an electric heater provided in the exhaust purification device; and temperature acquisition means for acquiring a temperature of the exhaust purification device, the control unit activates the electric heater when the temperature of the exhaust purification device is equal to or lower than a predetermined temperature, When the first motoring mode is performed when the temperature of the exhaust gas purification device is equal to or lower than the predetermined temperature, the output of the electric heater is increased compared to when the first motoring mode is not performed when the temperature is equal to or lower than the predetermined temperature.

2. The hybrid vehicle according to claim 1.

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