Driving assistance apparatus

1. A driving assistance apparatus that assists a vehicle, including an engine, in traveling, comprising:

an assistance control unit determining an on/off state of the engine; and

a drive control unit controlling driving of the engine on the basis of the on/off state determined by the assistance control unit, wherein

the assistance control unit acquires a quantity of power requested by a driver and switches the engine from the on state to the off state when the quantity of power is lower than or equal to a first threshold for setting the engine to the off state,

the assistance control unit determines whether the vehicle stops at a target stopping position, and

the assistance control unit sets the first threshold higher than a predetermined value when the assistance control unit determines that the vehicle stops at the target stopping position and the vehicle is able to reach the target stopping position without generating a driving force.

2. The driving assistance apparatus according to claim 1 , wherein the assistance control unit calculates a position at which the assistance control unit sets the first threshold to the higher value with reference to a position at which the vehicle is able to reach the target stopping position by coasting.

3. The driving assistance apparatus according to claim 2 , wherein the assistance control unit calculates the position at which the vehicle is able to reach the target stopping position by coasting on the basis of a current vehicle speed, a deceleration during coasting, and a distance to the target stopping position.

4. The driving assistance apparatus according to claim 1 , wherein the assistance control unit detects an accelerator operation state and detects the quantity of power on the basis of the accelerator operation state.

5. The driving assistance apparatus according to claim 1 , wherein the assistance control unit determines that the vehicle is able to reach the target stopping position without generating the driving force based upon passage of a position at which the vehicle is able to reach the target stopping position by coasting.

6. The driving assistance apparatus according to claim 1 , wherein the assistance control unit determines that the vehicle is able to reach the target stopping position without generating the driving force under a condition that the vehicle travels by coasting to a brake deceleration start position at which braking is started before the target stopping position.

7. The driving assistance apparatus according to claim 1 , wherein

the vehicle includes a motor generator that serves as a driving source and a battery that supplies electric power to the motor generator, and

the assistance control unit does not set the first threshold higher than the predetermined value when a state of charge of the battery is lower than a second threshold.

8. A driving assistance apparatus that assists a vehicle, including an engine, in traveling, comprising:

circuitry configured to:

determine an on/off state of the engine;

control driving of the engine on the basis of the determined on/off state;

acquire a quantity of power requested by a driver;

switch the engine from the on state to the off state when the quantity of power is lower than or equal to a first threshold for setting the engine to the off state,

determine whether the vehicle stops at a target stopping position; and

set the first threshold higher than a predetermined value when it is determined that the vehicle stops at the target stopping position and the vehicle is able to reach the target stopping position without generating a driving force.

9. The driving assistance apparatus according to claim 8 , wherein the circuitry is further configured to calculate a position at which the first threshold is set to the higher value with reference to a position at which the vehicle is able to reach the target stopping position by coasting.

10. The driving assistance apparatus according to claim 9 , wherein the circuitry is further configured to calculate the position at which the vehicle is able to reach the target stopping position by coasting on the basis of a current vehicle speed, a deceleration during coasting, and a distance to the target stopping position.

11. The driving assistance apparatus according to claim 8 , wherein the circuitry is further configured to detect an accelerator operation state and detect the quantity of power on the basis of the accelerator operation state.

12. The driving assistance apparatus according to claim 8 , wherein the circuitry is further configured to determine that the vehicle is able to reach the target stopping position without generating the driving force based upon passage of a position at which the vehicle is able to reach the target stopping position by coasting.

13. The driving assistance apparatus according to claim 8 , wherein the circuitry is further configured to determine that the vehicle is able to reach the target stopping position without generating the driving force under a condition that the vehicle travels by coasting to a brake deceleration start position at which braking is started before the target stopping position.

14. The driving assistance apparatus according to claim 8 , wherein

the vehicle includes a motor generator that serves as a driving source and a battery that supplies electric power to the motor generator, and

the circuitry is further configured to not set the first threshold higher than the predetermined value when a state of charge of the battery is lower than a second threshold.