Patent ID: 8677959
Filing Date: 2014-03-25
Classification: F01L,F02D,Y02T

Abstract:
1. A variable valve timing controller for an internal combustion engine having a crankshaft and a camshaft, the variable valve timing controller comprising: a hydraulic variable valve timing unit configured to adjust valve timing by changing a variable cam timing (VCT) phase that is a rotational phase of the camshaft relative to the crankshaft; a lock pin configured to lock the VCT phase at an intermediate lock position located within an adjustable range of the VCT phase; one single hydraulic control valve configured to control oil pressure that actuates the variable valve timing unit and the lock pin; and control means for controlling a valve drive electric current that is used for actuating the single hydraulic control valve, wherein: the control means operates the single hydraulic control valve under a plurality of control ranges; the control means controls the valve drive electric current to actuate the single hydraulic control valve based on a first control characteristic in the operation of the single hydraulic control valve under a first one of the plurality of control ranges; the control means controls the valve drive electric current to actuate the single hydraulic control valve based on a second control characteristic in the operation of the single hydraulic control valve under a second one of the plurality of control ranges; the first control characteristic is different from the second control characteristic; the first one of the plurality of control ranges is a phase control range, in which the single hydraulic control valve is operated to cause the VCT phase to coincide with a target phase that is determined in accordance with an operational condition; the second one of the plurality of control ranges is a lock pin control range, in which the single hydraulic control valve is operated to actuate the lock pin in a lock direction for locking the VCT phase and in a lock release direction for releasing the lock of the VCT phase; the control means controls the second control characteristic under the lock pin control range to have higher responsivity than the first control characteristic under the phase control range; the control means includes: the control characteristic of the electric current feed-back control in the lock pin control range is set to be faster than the control characteristic of the electric current feed-back control in the phase control range.