Valve timing control apparatus and valve timing control arrangement

A valve timing control apparatus for an internal combustion engine having an intake valve and an exhaust valve, the valve timing control apparatus comprising:

• a variable valve mechanism that uses oil pressure as a drive source to change a valve opening-closing characteristic of at least one of the intake valve and the exhaust valve;
• dead zone width learning means for executing a learning operation, in which the dead zone width learning means changes a control amount used for controlling the variable valve mechanism by changing a target value of the valve opening-closing characteristic from a first value to a second value in order to learn a value of one of a width of a dead zone and a dead zone width correlation parameter that is correlated with the dead zone width when the valve opening-closing characteristic is maintained at the first value, wherein:
• the variable valve mechanism is limited from being controlled even when the control amount of the variable valve mechanism is changed within the dead zone;
• the dead zone width learning means executes the learning operation when a predetermined dead zone width learning execution condition is established;
• and
• the dead zone width learning means learns the value of the one of the dead zone width and the dead zone width correlation parameter during a period before a predetermined learning time has elapsed since a time, at which the dead zone width learning means forcibly changes the target value;
• and
• control means for offset-correcting the control amount used for controlling the variable valve mechanism based on the learned value learned by the dead zone width learning means after the dead zone width learning means completes the learning operation, wherein the control means drives the variable valve mechanism based on the corrected control amount.

A valve timing control apparatus for an internal combustion engine having an intake valve and an exhaust valve, the valve timing control apparatus comprising:

• a variable valve mechanism that uses oil pressure as a drive source to change a valve opening-closing characteristic of at least one of the intake and exhaust valves;
• dead zone width learning means for executing a learning operation, in which the dead zone width learning means changes a control amount used for controlling the variable valve mechanism by changing a target value of the valve opening-closing characteristic from a first value to a second value in order to learn a value of a dead zone width correlation parameter that is correlated with a width of a dead zone when the valve opening-closing characteristic is maintained at the first value, wherein the variable valve mechanism is limited from being controlled even when the control amount of the variable valve mechanism is changed within the dead zone;
• control means for driving the variable valve mechanism by offset correcting the control amount of the variable valve mechanism based on the learned value of the dead zone width correlation parameter after the learning operation by the dead zone width learning means is completed;
• and
• a temperature detecting unit that detects an oil temperature parameter that is associated with one of an oil temperature of the variable valve mechanism and a temperature correlated with the oil temperature, wherein:
• the dead zone width learning means forcibly changes the target value in order to learn the value of the dead zone width correlation parameter when a predetermined dead zone width learning execution condition is established;
• and
• the dead zone width learning means changes one of a forcible change width of the target value at the beginning of the learning operation and a control gain during the learning operation in accordance with the oil temperature parameter detected by the temperature detecting unit, the forcible change width corresponding to a difference between the first value and the second value of the target value of the valve opening-closing characteristic.

A valve timing control apparatus for an internal combustion engine having an intake valve and an exhaust valve, the valve timing control apparatus comprising:

• a variable valve mechanism that adjusts valve timing of at least one of the intake valve and the exhaust valve based on oil pressure serving as a drive source;
• an oil pressure control device that controls pressure of oil that drives the variable valve mechanism;
• control means for controlling the oil pressure control device such that an actual value of the valve timing becomes a target value of the valve timing, wherein:
• the control means computes a control amount used for controlling the oil pressure control device based on a feed-back correction amount, which is determined based on a difference between the target value and the actual value of the valve timing and based on a hold control amount, which is required to maintain the actual value of the valve timing under a constant state;
• a temperature detecting unit that detects an oil temperature parameter that is one of an oil temperature and a temperature that is correlated with the oil temperature;
• a nonvolatile storage unit that prestores hold control amount standard characteristic data that defines a relation between the oil temperature parameter and the hold control amount;
• and
• hold control amount learning means for learning a value of the hold control amount of a predetermined temperature section, wherein:
• the control means determines the hold control amount of a temperature section corresponding to the oil temperature parameter based on the learned value of the hold control amount of the predetermined temperature section and based on a retrieved value of the hold control amount standard characteristic data, which is retrieved from the storage unit, in order to compute the control amount of the oil pressure control device.

24 The valve timing control apparatus according to claim 23, wherein:

• the temperature section is one of a plurality of temperature sections;
• the hold control amount standard characteristic data stored in the storage unit includes a temperature correction amount of each of the plurality of temperature sections, the temperature correction amount being based on the hold control amount of the predetermined temperature section;
• the control means determines the hold control amount of each of the plurality of temperature sections by correcting the learned value of the hold control amount of the predetermined temperature section, which is learned by the hold control amount learning means, by using the temperature correction amount retrieved from the storage unit for each of the plurality of temperature sections;
• and
• the control means computes the control amount of the oil pressure control device based on the hold control amount of one of the plurality of temperature sections, to which the oil temperature parameter presently detected by the temperature detecting unit corresponds.