Vehicle traveling control method and vehicle traveling control device

1. A vehicle traveling control method comprising:

determining a driver's intention for acceleration during vehicle traveling;

predicting, when a determination is made that the driver has no intention for acceleration, which is superior between a first fuel consumption reduction effect by inertial traveling and a second fuel consumption reduction effect by deceleration energy regeneration, the inertial traveling making the vehicle travel, with power transmission disconnected between an engine and a drive wheel of the vehicle, and the deceleration energy regeneration inputting rotational power of the drive wheel of the vehicle to an electric motor;

performing inertial traveling when a prediction is made that the first fuel consumption reduction effect by inertial traveling is superior to the second fuel consumption reduction effect by deceleration energy regeneration;

performing deceleration energy regeneration when a prediction is made that the first fuel consumption reduction effect by inertial traveling is not superior to the second fuel consumption reduction effect by deceleration energy regeneration;

detecting a speed of the vehicle upon determining that the driver has no intention for acceleration; and

predicting, when the speed is equal to or higher than a speed threshold, that the first fuel consumption reduction effect by inertial traveling is superior to the second fuel consumption reduction effect by deceleration energy regeneration, and when the speed is less than the speed threshold, that the first fuel consumption reduction effect by inertial traveling is not superior to the second fuel consumption reduction effect by deceleration energy regeneration.

2. The vehicle traveling control method according to claim 1 , wherein inertial traveling is continued when the speed drops below the threshold during performing inertial traveling.

3. The vehicle traveling control method according to claim 1 , wherein deceleration energy regeneration is continued when the speed increases to or above the threshold during performing deceleration energy regeneration on a downward slope.

4. A vehicle traveling control method comprising:

determining a driver's intention for acceleration during vehicle traveling;

predicting, when a determination is made that the driver has no intention for acceleration, which is superior between a first fuel consumption reduction effect by inertial traveling and a second fuel consumption reduction effect by deceleration energy regeneration, the inertial traveling making the vehicle travel, with power transmission disconnected between an engine and a drive wheel of the vehicle, and the deceleration energy regeneration inputting rotational power of the drive wheel of the vehicle to an electric motor;

performing inertial traveling when a prediction is made that the first fuel consumption reduction effect by inertial traveling is superior to the second fuel consumption reduction effect by deceleration energy regeneration;

performing deceleration energy regeneration when a prediction is made that the first fuel consumption reduction effect by inertial traveling is not superior to the second fuel consumption reduction effect by deceleration energy regeneration;

detecting a distance and a relative speed between the vehicle and an object which can be a stopping factor for inertial traveling, upon determining that the driver has no intention for acceleration; and

predicting, according to the distance and the relative speed, whether or not the first fuel consumption reduction effect by inertial traveling is superior to the second fuel consumption reduction effect by deceleration energy regeneration.

5. The vehicle traveling control method according to claim 4 , comprising:

determining, according to one of the distance and the relative speed, a threshold of the other of the distance and the relative speed; and

predicting whether or not the first fuel consumption reduction effect by inertial traveling is superior to the second fuel consumption reduction effect by deceleration energy regeneration, according to a result of comparison of the other with the threshold.

6. The vehicle traveling control method according to claim 4 , wherein the object is a preceding car traveling ahead of the vehicle.

7. The vehicle traveling control method according to claim 4 , wherein the object is a red traffic light on a route of the vehicle and the relative speed is a traveling speed of the vehicle.

8. The vehicle traveling control method according to claim 4 , wherein the object is an intersection where the vehicle will next turn to right or left on a scheduled route of the vehicle and the relative speed is a traveling speed of the vehicle.

9. A vehicle traveling control device including:

an accelerator depression degree detector configured to detect accelerator depression degree by a driver; and

a controller configured to control an electric motor and a clutch for transmitting power between an engine and a drive wheel and between the electric motor and the drive wheel,

wherein, when the accelerator depression degree is no longer detected, the controller predicts which is superior between a first fuel consumption reduction effect by inertial traveling and a second fuel consumption reduction effect by deceleration energy regeneration, the inertial traveling making the vehicle travel, with power transmission disconnected between the engine and the drive wheel, and the deceleration energy regeneration inputting rotational power of the drive wheel to the electric motor,

wherein, when a prediction is made that the first fuel consumption reduction effect by inertial traveling is superior to the second fuel consumption reduction effect by deceleration energy regeneration, the controller disconnects the engine from the drive wheel by the clutch,

wherein, when a prediction is made that the first fuel consumption reduction effect by inertial traveling is not superior to the second fuel consumption reduction effect by deceleration energy regeneration, the controller connects the motor to the drive wheel by the clutch,

wherein, the controller detects a speed of the vehicle upon determining that the driver has no intention for acceleration; and

wherein, the controller predicts, when the speed is equal to or higher than a speed threshold, that the first fuel consumption reduction effect by inertial traveling is superior to the second fuel consumption reduction effect by deceleration energy regeneration, and when the speed is less than the speed threshold, that the first fuel consumption reduction effect by inertial traveling is not superior to the second fuel consumption reduction effect by deceleration energy regeneration.

10. A vehicle traveling control device including:

an accelerator depression degree detector configured to detect accelerator depression degree by a driver; and

a controller configured to control an electric motor and a clutch for transmitting power between an engine and a drive wheel and between the electric motor and the drive wheel,

wherein, when the accelerator depression degree is no longer detected, the controller predicts which is superior between a first fuel consumption reduction effect by inertial traveling and a second fuel consumption reduction effect by deceleration energy regeneration, the inertial traveling making the vehicle travel, with power transmission disconnected between the engine and the drive wheel, and the deceleration energy regeneration inputting rotational power of the drive wheel to the electric motor,

wherein, when a prediction is made that the first fuel consumption reduction effect by inertial traveling is superior to the second fuel consumption reduction effect by deceleration energy regeneration, the controller disconnects the engine from the drive wheel by the clutch,

wherein, when a prediction is made that the first fuel consumption reduction effect by inertial traveling is not superior to the second fuel consumption reduction effect by deceleration energy regeneration, the controller connects the motor to the drive wheel by the clutch,

wherein, the controller detects a distance and a relative speed between the vehicle and an object which can be a stopping factor for inertial traveling, upon determining that the driver has no intention for acceleration; and

wherein, the controller predicts, according to the distance and the relative speed, whether or not the first fuel consumption reduction effect by inertial traveling is superior to the second fuel consumption reduction effect by deceleration energy regeneration.