Hybrid vehicle

A hybrid vehicle, comprising:

• an internal combustion engine;
• an electric motor;
• an electric storage device providing and receiving electric power to and from the electric motor;
• an automatic transmission including a first converting mechanism connected to the electric motor, the first converting mechanism is transmitted with a driving force of the internal combustion engine selectively via a first make-and-break element, and a second converting mechanism which is transmitted with the driving force of the internal combustion engine selectively via a second make-and-break element, wherein a motive power output from the internal combustion engine and the electric motor is changed to a plurality of speed stages and is output;
• a remaining capacity detecting element which detects a remaining capacity of the electric storage device;
• a required driving force acquiring element which acquires a required driving force that is necessary to be output;
• an electric motor driving force acquiring element which acquires a maximum electric motor driving force capable of being output according to each speed stage by the motive power output from the electric motor, at least taking into consideration the remaining capacity of the electric storage device detected by the remaining capacity detecting element;
• a control element which determines a highest speed stage in which the electric motor is capable of outputting the required driving force, when the required driving force acquired by the required driving force acquiring element is equal to or smaller than the maximum electric motor driving force acquired by the electric motor driving force acquiring element, controls the automatic transmission so that the determined speed stage is set, and controls so as to make the vehicle travel only from the driving force of the electric motor, by setting the first make-and-break element and the second make-and-break element to an interrupted state;
• a variable speed map which selects a speed stage of the automatic transmission on the basis of the required driving force acquired by the required driving force acquiring element, and
• a zone distinguishing element which distinguishes, on the basis of the detected remaining capacity detected by the remaining capacity detecting element, a standard zone, a discharge limited zone in which the remaining capacity is smaller than the standard zone, a discharge prohibited zone in which the remaining capacity is smaller than the discharge limited zone, and a charge prohibited zone in which the remaining capacity is larger than the standard zone,
• wherein the first converting mechanism includes a first input shaft which is transmitted with the driving force of the internal combustion engine selectively via the first make-and-break element, and which is connected to the electric motor, and a first selecting element which couples the first input shaft and an output mechanism via a gear train selected from a plurality of gear trains,
• the second converting mechanism includes a second input shaft which is transmitted with the driving force of the internal combustion engine selectively via the second make-and-break element, and a second selecting element which couples the second input shaft and the output mechanism via a gear train selected from a plurality of the gear trains, and
• when the vehicle is made to travel by the driving force of the internal combustion engine by establishing the speed stage of the automatic transmission with the coupled state by the first selecting element, in the case of changing to a lower speed stage side of the automatic transmission by referring to the variable speed map, the control element establishes a speed stage lower by one speed stage from the speed stage by setting the first make-and-break element to the transmission interrupted state and the second selecting element to the connected state and the second make-and-break element to the transmission state, according to an estimated value of the required driving force in the case where the zone distinguished by the zone distinguishing element is the standard zone, and thereafter make the electric motor to regenerate power by either maintaining the current speed stage or setting the first selecting element to the state where a speed stage further lower by one speed stage is established.