Control device and control method for internal combustion engine

1. A control device for an internal combustion engine, the internal combustion engine including an intake valve, a cam, a cam position sensor, a crank position sensor, and an intake-side variable valve timing mechanism,

the intake-side variable valve timing mechanism configured to:

be driven by an electric motor,

operate within a predetermined phase angle range, and continuously advance and retard a phase of the cam that actuates the intake valve;

the control device comprising an electronic control unit configured to:

determine that there is a failure in the crank position sensor;

when the electronic control unit has determined that there is the failure in the crank position sensor, actuate the intake-side variable valve timing mechanism toward a retardation side, position the intake-side variable valve timing mechanism at a prescribed position, and execute fail-safe control based on a signal from the cam position sensor instead of a signal from the crank position sensor, the prescribed position being a most retarded position in the predetermined phase angle range;

determine that an engine rotation speed is higher than or equal to a predetermined value at a timing at which the electronic control unit has determined that there is the failure in the crank position sensor;

when the electronic control unit has determined that the engine rotation speed is higher than or equal to the predetermined value, after the electronic control unit has determined that there is the failure in the crank position sensor, and after the intake-side variable valve timing mechanism is positioned at the most retarded position, begin to stop energization of the electric motor while the intake-side variable valve timing mechanism remains positioned at the most retarded position; and

continue energization of the electric motor when the engine rotation speed is lower than the predetermined value after the intake-side variable valve timing mechanism is positioned at the most retarded position.

2. The control device according to claim 1 , wherein

the electronic control unit is configured to stop supplying fuel to the internal combustion engine until the intake-side variable valve timing mechanism reaches the prescribed position, when the electronic control unit has determined that there is the failure in the crank position sensor and has actuated the intake-side variable valve timing mechanism toward the retardation side.

3. The control device according to claim 1 , wherein

the internal combustion engine is mounted on a vehicle, and

the fail-safe control is a control for allowing the vehicle to operate in a state in which a throttle opening degree is limited irrespective of a signal from an acceleration operation amount sensor.

4. The control device according to claim 3 , wherein

a timing at which the signal is generated from the cam position sensor is set in correspondence with a timing at which fuel is injected to at least one cylinder during the fail-safe control or a timing at which the at least one cylinder is ignited during the fail-safe control.

5. A control method for an internal combustion engine, wherein

the internal combustion engine includes an intake valve, a cam, a cam position sensor, a crank position sensor, an intake-side variable valve timing mechanism, and an electronic controller,

the control method comprising:

driving the intake-side variable valve timing mechanism by an electric motor;

operating the intake-side variable valve timing mechanism within a predetermined phase angle range;

continuously advancing and retarding, with the intake-side variable valve timing mechanism, operation timing of the intake valve;

determining, by the electronic controller, that there is a failure in the crank position sensor;

retarding, by the electronic controller, when the electronic controller has determined that there is the failure in the crank position sensor, the operation timing of the intake valve to a prescribed position, and executing fail-safe control based on a signal from the cam position sensor instead of a signal from the crank position sensor, the prescribed position being a most retarded position in the predetermined phase angle range;

determining, by the electronic controller, that an engine rotation speed is higher than or equal to a predetermined value at a timing at which the electronic controller has determined that there is the failure in the crank position sensor;

when the electronic controller has determined that the engine rotation speed is higher than or equal to the predetermined value, after the electronic controller has determined that there is the failure in the crank position sensor, and after the intake-side variable valve timing mechanism is positioned at the most retarded position, begin stopping, by the electronic controller, energization of the electric motor while the intake-side variable valve timing mechanism remains positioned at the most retarded position; and

continuing, by the electronic controller, energization of the electric motor when the engine rotation speed is lower than the predetermined value after the intake-side variable valve timing mechanism is positioned at the most retarded position.

6. The control method according to claim 5 , further comprising:

stopping, by the electronic controller, supplying fuel to the internal combustion engine until the intake-side variable valve timing mechanism reaches the prescribed position, when the electronic controller has determined that there is the failure in the crank position sensor and has actuated the intake-side variable valve timing mechanism toward the retardation side.

7. The control method according to claim 5 , wherein

the internal combustion engine is mounted on a vehicle, and

the fail-safe control is a control for allowing the vehicle to operate in a state in which a throttle opening degree is limited irrespective of a signal from an acceleration operation amount sensor.

8. The control method according to claim 7 , wherein

a timing at which the signal is generated from the cam position sensor is set in correspondence with a timing at which fuel is injected to at least one cylinder during the fail-safe control or a timing at which the at least one cylinder is ignited during the fail-safe control.

9. A control device for an internal combustion engine, the internal combustion engine including an intake valve, a cam, a cam position sensor, a crank position sensor, and an intake-side variable valve timing mechanism,

the intake-side variable valve timing mechanism configured to:

be driven by an electric motor,

operate within a predetermined phase angle range, and

continuously advance and retard a phase of the cam that actuates the intake valve;

the control device comprising processing circuitry configured to:

determine that there is a failure in the crank position sensor;

when the processing circuitry has determined that there is the failure in the crank position sensor, actuate the intake-side variable valve timing mechanism toward a retardation side, position the intake-side variable valve timing mechanism at a prescribed position, and execute fail-safe control based on a signal from the cam position sensor instead of a signal from the crank position sensor, the prescribed position being a most retarded position in the predetermined phase angle range;

determine that an engine rotation speed is higher than or equal to a predetermined value at a timing at which the processing circuitry has determined that there is the failure in the crank position sensor;

when the processing circuitry has determined that the engine rotation speed is higher than or equal to the predetermined value, after the processing circuitry has determined that there is the failure in the crank position sensor, and after the intake-side variable valve timing mechanism is positioned at the most retarded position, begin to stop energization of the electric motor while the intake-side variable valve timing mechanism remains positioned at the most retarded position; and

continue energization of the electric motor when the engine rotation speed is lower than the predetermined value after the intake-side variable valve timing mechanism is positioned at the most retarded position.

10. The control device according to claim 9 , wherein

the processing circuitry is configured to stop supplying fuel to the internal combustion engine until the intake-side variable valve timing mechanism reaches the prescribed position, when the processing circuitry has determined that there is a failure in the crank position sensor and has actuated the intake-side variable valve timing mechanism toward the retardation side.

11. The control device according to claim 9 , wherein

the internal combustion engine is mounted on a vehicle, and

the fail-safe control is a control for allowing the vehicle to operate in a state in which a throttle opening degree is limited irrespective of a signal from an acceleration operation amount sensor.

12. The control device according to claim 11 , wherein

a timing at which the signal is generated from the cam position sensor is set in correspondence with a timing at which fuel is injected to at least one cylinder during the fail-safe control or a timing at which the at least one cylinder is ignited during the fail-safe control.

13. The control device according to claim 1 , wherein

after the electronic control unit has determined that there is the failure in the crank position sensor, the electronic control unit is configured to use the electric motor to actuate the intake-side variable valve timing mechanism and position the intake-side variable valve timing mechanism at the most retarded position.

14. The control method according to claim 5 , wherein

the retarding, by the electronic controller, includes using the electronic motor to actuate the intake-side variable valve timing mechanism and position the intake-side variable valve timing mechanism at the most retarded position after the electronic controller has determined that there is the failure in the crank position sensor.

15. The control device according to claim 9 , wherein

after the processing circuitry has determined that there is the failure in the crank position sensor, the processing circuitry is configured to use the electric motor to actuate the intake-side variable valve timing mechanism and position the intake-side variable valve timing mechanism at the most retarded position.