Vehicle and method of controlling the same

1. A vehicle, comprising:

an electric motor that delivers power to a drive shaft coupled to driving wheels;

an electric storage device that supplies and receives electric power to and from the electric motor;

an accelerator operation amount obtaining device that obtains an accelerator operation amount as an amount of operation of an accelerator pedal by a driver;

a vehicle speed obtaining device that obtains a vehicle speed;

a gear range selecting device that permits the driver to select a desired gear range from a normal running range and a plurality of virtual gear ranges;

a restriction storing device that stores a plurality of restrictions that are created for the respective virtual gear ranges, so that, in each of said plurality of virtual gear ranges, a required driving force as a driving force to be applied to the drive shaft corresponding to the same accelerator operation amount, increases as the vehicle speed increases, and the required driving force, corresponding to the same accelerator operation amount increases as the virtual gear range is shifted to a lower range when the vehicle speed is constant;

a required driving force setting device, when one of the virtual gear ranges is selected by the driver, that sets the required driving force corresponding to the accelerator operation amount obtained by the accelerator operation amount obtaining device and the vehicle speed obtained by the vehicle speed obtaining device, using the restriction corresponding to the selected virtual gear range; and

a control device that controls the electric motor so that power based on the required driving force set by the required driving force setting device is delivered to the drive shaft.

2. The vehicle according to claim 1 , wherein the normal running range is a drive range for forward running of the vehicle.

3. The vehicle according to claim 1 , wherein:

at least one of said plurality of restrictions corresponding to a predetermined first one of the virtual gear ranges is created such that the accelerator operation amount obtained by the accelerator operation amount obtaining device is converted into a larger value than an actual value as the vehicle speed is higher, so that the required driving force corresponding to the same accelerator operation amount tends to be increased as the vehicle speed is higher;

at least one of said plurality of restrictions corresponding to a predetermined second one of the virtual gear ranges is created such that the accelerator operation amount obtained by the accelerator operation amount obtaining device is converted into a smaller value than the actual value as the vehicle speed is lower, so that the required driving force corresponding to the same accelerator operation amount tends to be reduced as the vehicle speed is lower; and

the predetermined first one of the virtual gear ranges is a lower virtual gear range as compared to the predetermined second one of the virtual gear ranges.

4. The vehicle according to claim 1 , further comprising:

an operating mode selecting device that permits the driver to select a desired operating mode from a first operating mode for normal running, a second operating mode in which an output response of the driving force for running the vehicle is prioritized as compared with the first operating mode, and a third operating mode in which energy efficiency is prioritized as compared with the first and second operating modes; and

a controlled accelerator operation amount setting device that sets a controlled accelerator operation amount to the accelerator operation amount obtained by the accelerator operation amount obtaining device when the normal running range is selected and the first operating mode is selected by the driver, sets the controlled accelerator operation amount corresponding to the accelerator operation amount obtained by the accelerator operation amount obtaining device according to a given restriction on increase of the operation amount, such that the controlled accelerator operation amount tends to be larger than the accelerator operation amount, when the normal running range is selected and the second operating mode is selected by the driver, and sets the controlled accelerator operation amount corresponding to the accelerator operation amount obtained by the accelerator operation amount obtaining device according to a given restriction on reduction of the operation amount, such that the controlled accelerator operation amount tends to be smaller than the accelerator operation amount, when the normal running range is selected and the third operating mode is selected by the driver,

wherein said plurality of restrictions are created based on the given restriction on increase of the operation amount and the given restriction on reduction of the operation amount, and

wherein, when the normal running range is selected by the driver, the required driving force setting device sets the required driving force, using a restriction in setting of the required driving force for normal running, which defines relationships among the controlled accelerator operation amount, the vehicle speed and the required driving force, the controlled accelerator operation amount set by the controlled accelerator operation amount setting device, and the vehicle speed obtained by the vehicle speed obtaining device.

5. The vehicle according to claim 4 , wherein:

said plurality of restrictions are a plurality of restrictions in setting of the controlled accelerator operation amount, each of which is created so as to define a relationship between the accelerator operation amount obtained by the accelerator operation amount obtaining device and the controlled accelerator operation amount with respect to the respective virtual gear ranges, based on the given restriction on increase of the operation amount and the given restriction on reduction of the operation amount;

when one of the virtual gear ranges is selected by the driver, the controlled accelerator operation amount setting device sets the controlled accelerator operation amount using the restriction in setting of the controlled accelerator operation amount corresponding to the selected virtual gear range and the accelerator operation amount obtained by the accelerator operation amount obtaining device; and

when one of the virtual gear ranges is selected by the driver, the required driving force setting device sets the required driving force, using the restriction in setting of the required driving force for normal running, the controlled accelerator operation amount set by the controlled accelerator operation amount setting device, and the vehicle speed obtained by the vehicle speed obtaining device.

6. The vehicle according to claim 4 , wherein:

said plurality of restrictions are a plurality of restrictions in setting of the required driving force, each of which is created so as to define relationships among the accelerator operation amount, the vehicle speed and the required driving force with respect to the respective virtual gear ranges, based on the given restriction on increase of the operation amount, the given restriction on reduction of the operation amount, and the restriction in setting of the required driving force for normal running; and

when one of the virtual gear ranges is selected by the driver, the required driving force setting device sets the required driving force, using the restriction in setting of the required driving force corresponding to the selected virtual gear range, the accelerator operation amount obtained by the accelerator operation amount obtaining device, and the vehicle speed obtained by the vehicle speed obtaining device.

7. The vehicle according to claim 1 , further comprising:

an internal combustion engine;

a second electric motor that delivers and receives power; and

a power distributing device that is connected to three shafts including an output shaft of the internal combustion engine, a rotating shaft of the second electric motor and the drive shaft, and is operable to deliver or receive power based on power received from or delivered to two of the three shafts, to or from the remaining shaft,

wherein the control device controls the internal combustion engine, the electric motor and the second electric motor so that power based on the required driving force set by the required driving force setting device is delivered to the drive shaft.

8. A method of controlling a vehicle including an electronic control unit, an electric motor that delivers power to a drive shaft coupled to driving wheels, an electric storage device that supplies and receives electric power to and from the electric motor, an accelerator operation amount obtaining device that obtains an accelerator operation amount as an amount of operation of an accelerator pedal by a driver, a vehicle speed obtaining device that obtains a vehicle speed, and a gear range selecting device that permits the driver to select a desired gear range from a normal running range and a plurality of virtual gear ranges, comprising:

when one of the virtual gear ranges is selected by the driver, extracting, by the electronic control unit, a restriction corresponding to the virtual gear range selected by the driver, from a plurality of restrictions that are created for the respective virtual gear ranges, such that, in each of said plurality of virtual gear ranges a required driving force as a driving force to be applied to the drive shaft, which corresponds to the same accelerator operation amount, increases as the vehicle speed increases, and the required driving force corresponding to the same accelerator operation amount increases as the virtual gear range is shifted to a lower range when the vehicle speed is constant, and setting, by the electronic control unit, the required driving force corresponding to the accelerator operation amount obtained by the accelerator operation amount obtaining device and the vehicle speed obtained by the vehicle speed obtaining device, using the extracted restriction; and

controlling, by the electronic control unit, the electric motor so that power based on the set required driving force is delivered to the drive shaft.

9. The method according to claim 8 , wherein the normal running range is a drive range for forward running of the vehicle.