CROSS REFERENCE TO RELATED APPLICATIONS

This application is based on and claims priority under 35 U.S.C. § 119 to Japanese Patent Application 2020-068403, filed on Apr. 6, 2020, the entire content of which is incorporated herein by reference.

TECHNICAL FIELD

This disclosure relates to a valve timing controller that sets an opening/closing timing of a valve of an internal combustion engine by a driving force of an electric motor.

BACKGROUND DISCUSSION

In the related art, a valve timing controller capable of changing an opening/closing timing of an intake valve or an exhaust valve in accordance with an operation situation of an internal combustion engine (hereinafter, also referred to as an “engine”) has been practically used. For example, the valve timing controller has a mechanism for changing the opening/closing timing of the intake valve or the exhaust valve by changing a relative rotation phase of a driven-side rotation member (hereinafter, also simply referred to as a “relative rotation phase”) with respect to rotation of a driving-side rotation member which is caused by an operation of the engine. In addition, in recent years, idling stop control for temporarily stopping the engine when a vehicle is stopped by stepping on a brake pedal during normal operation has been practically used. In the control, when the engine is stopped, the operation is changed to the relative rotation phase which facilitates restarting of the engine in a high temperature state. As a technique relating to the control, JP 2010-84587A (Reference 1) and JP 2019-127887A (Reference 2) below disclose the following techniques.

Reference 1 discloses a configuration in which an intake type valve timing controller (intake VVT in Reference 1) is controlled to a retarding side when the internal combustion engine provided in the vehicle is automatically stopped.

That is, when an engine automatic stop condition is satisfied in an idling operation state of the internal combustion engine, the valve timing controller is automatically controlled to the retarding side, and the internal combustion engine is automatically controlled to be stopped. According to the control performed in this way, Reference 1 enables quick starting by reducing an effective compression ratio of the internal combustion engine when starting the internal combustion engine.

In addition, Reference 2 discloses a configuration as follows. When performing a driving stop process of the internal combustion engine (engine in Reference 2) provided in the vehicle, the valve timing controller maintains the opening/closing timing (timing) at which the relative rotation phase of the valve timing controller (variable valve timing mechanism in Reference 2) advances from a most retarding phase. The opening/closing timing of the valve timing controller is set to the most retarding phase after the driving stop process of the engine is completed. According to the control performed in this way, Reference 2 enables satisfactory starting of the internal combustion engine.

In the vehicle including the internal combustion engine, automatic stop control is performed as follows. The internal combustion engine is automatically stopped when a vehicle speed is lowered due to a deceleration operation, for example, such as a driver's stepping on the brake pedal so that fuel consumption is suppressed during idling.

It is also conceivable to perform automatic start control as follows. After the internal combustion engine is stopped by the above-described automatic stop control, for example, when the driver releases an operation of the brake pedal and steps on an accelerator pedal, the internal combustion engine is started by driving a starter motor.

For this reason, in Reference 1, in order to quickly start the internal combustion engine, control for setting the valve timing controller of an intake camshaft to the most retarding phase is performed when the internal combustion engine is automatically stopped.

Here, in view of the intake VVT disclosed in Reference 1 in which the opening/closing timing is set by driving an electric motor, after the internal combustion engine is stopped, a pressure is applied inside a cylinder, a rotational force is applied in a direction in which weights of a plurality of pistons are balanced in a plurality of cylinders, or a biasing force of a valve spring that applies the biasing force in a closing direction of the intake valve is applied to a cam surface. For this reason, the opening/closing timing of the intake camshaft may be changed to an advancing side.

In this way, when the relative rotation phase of the valve timing controller is changed after the internal combustion engine is stopped, a compression ratio is increased when starting the internal combustion engine, and a load applied to the starter motor is increased. Consequently, the increased load hinders the quick starting, and startability is degraded.

In addition, Reference 2 does not disclose a control mode of an electric actuator in order to set the opening/closing timing to the most retarding phase after the internal combustion engine is stopped. Accordingly, for example, it is conceivable that the electric actuator is driven for a set time or that the electric actuator is driven by a set amount (for example, a rotation speed). However, there is room for improvement in control accuracy.

A need thus exists for a valve timing controller which is not susceptible to the drawback mentioned above.

SUMMARY

A feature of a valve timing controller according to an aspect of this disclosure resides in that the valve timing controller includes a driving-side rotation member rotatable around a rotation axis and rotating in synchronization with a crankshaft of an internal combustion engine, a driven-side rotation member rotatable around the rotation axis and rotating integrally with a camshaft for opening and closing a valve of the internal combustion engine, a phase regulating mechanism that sets a relative rotation phase of the driving-side rotation member and the driven-side rotation member by a driving force of an electric motor, a detection unit that detects the relative rotation phase, a stop control portion that displaces the relative rotation phase by controlling the electric motor to stop the internal combustion engine after the relative rotation phase reaches a stop phase, and a correction control portion that displaces the relative rotation phase in a direction closer to the stop phase by controlling the electric motor, when the detection unit detects that the relative rotation phase is displaced beyond a set amount from the stop phase, in a state where the internal combustion engine is stopped by the stop control portion.

