Travel assistance apparatus for hybrid vehicle

1. A travel assistance apparatus for a hybrid vehicle including an engine, a motor, and a battery, the travel assistance apparatus comprising an electronic control unit configured to:

draw up a travel plan in which any one of drive modes, including a charge depleting mode and a charge sustaining mode, is assigned to each of travel segments of a scheduled travel route from a current position to a destination,

determine whether a travel assistance control for causing the hybrid vehicle to travel according to the drawn up travel plan has been executed yet after the travel plan is drawn up,

based upon the determination that travel assistance control for causing the hybrid vehicle to travel according to the drawn up travel plan has not been executed yet after the travel plan is drawn up, and based upon a determination that a total of consumption energy that is consumed in the travel segments is greater than a value obtained by adding a first margin value to a remaining battery power, execute the travel assistance control so as to cause the hybrid vehicle to travel according to the drawn up travel plan, and

based upon the determination that travel assistance control for causing the hybrid vehicle to travel according to the drawn up travel plan has been executed after the travel plan is drawn up, and based upon a determination that the total of consumption energy that is consumed in the travel segments is greater than a value obtained by adding a second margin value less than the first margin value to the remaining battery power, maintain or adjust the travel plan and execute the travel assistance control so as to cause the hybrid vehicle to travel according to the maintained or adjusted travel plan.

2. The travel assistance apparatus according to claim 1 , wherein

the electronic control unit is configured to, while the electronic control unit is executing the travel assistance control, determine to suspend the travel assistance control when at least one of following cases is appropriate, a case where information on the travel segments is lost, a case where a position of the host vehicle is lost, and a case where a system is shut down without a change of the destination or the scheduled travel route.

3. The travel assistance apparatus according to claim 1 , wherein

the electronic control unit is configured to, while the electronic control unit is executing the travel assistance control, determine to exit the travel assistance control when at least one of following cases is appropriate, a case where the destination is changed, a case where the hybrid vehicle reaches the destination, a case where the remaining battery power changes, and a case where an operation to exit the travel assistance control is performed.

4. The travel assistance apparatus according to claim 1 , wherein

the electronic control unit is configured to, when the travel assistance control is being executed, maintain or adjust the travel plan and control the travel assistance control on condition that the total of consumption energy that is consumed in the travel segments is greater than a value obtained by adding a third margin value less than the first margin value to the remaining battery power.

5. The travel assistance apparatus according to claim 4 , wherein

the third margin value is equal to the second margin value.

6. The travel assistance apparatus according to claim 5 , wherein the second margin value is any one of zero and a value that reduces with time.