US 6,330,870 B1 · Variable valve timing control system

Abstract

A variable valve timing adjuster with an intermediate lock mechanism learns a lock position and a lock release control. During a lock control, a learning of the lock position from a real camshaft phase is repeated to update the learned value, and the learning is ended when it is judged that the learned values have converged. At this time, when the learned values of the lock position do not converge even if the number of learning of the lock position exceeds a predetermined value, an insufficient lock state is judged, and the learned value of the lock position is set to an initial value or the learned value at the previous lock control thereby to make a lock release control. During the lock release control, on the other hand, the control (or the lock release control) of a hydraulic control valve is learned. When the lock cannot be released during the lock release control, the lock release control (or the learned value) is corrected in a direction to facilitate the lock release. When the correction of the lock release control is repeated a predetermined or more number of times or when the lock release control goes outside a predetermined range, the lock release failure is judged.

Claims41

Dependent claims

A variable valve timing control system for an internal combustion engine, comprising:

a variable valve timing adjuster for making the valve timing variable by changing the rotational phase (as will be called the “camshaft phase”) of a camshaft with respect to the crankshaft of the internal combustion engine, said variable valve timing adjuster including a lock mechanism for locking said camshaft phase at a substantially intermediate lock position of its adjustable range when the variable valve timing control is not made, wherein the oil pressure for driving said lock mechanism and said variable valve timing adjuster is controlled by a hydraulic control valve,
wherein the improvement comprises:
lock position learning means for learning said lock position on the basis of said camshaft phase which is detected during a lock control for locking said camshaft phase at said lock position.

A variable valve timing control system for an internal combustion engine, comprising:

valve timing control means for controlling a valve timing variably by changing the rotational phase (as will be called the “camshaft phase”) of a camshaft with respect to the crankshaft of the internal combustion engine with an oil pressure;
and
lock means biased for locking said camshaft phase at an intermediate lock means, which is located at a substantially center of the adjustable range thereof, during the stop or at the start of the internal combustion engine,
wherein the improvement comprises:
lock release detection means for detecting the lock release of said lock means,
wherein said valve timing control means starts a feedback control of the valve timing after said lock release detection means detects the lock release of said lock means.

3 more elements

A variable valve timing control system for an internal combustion engine, comprising:

valve timing control means for controlling a valve timing variably by changing the rotational phase (as will be called the “camshaft phase”) of a camshaft with respect to the crankshaft of the internal combustion engine with an oil pressure;
lock means biased for locking said camshaft phase at an intermediate lock means, which is located at a substantially center of the adjustable range thereof, during the stop or at the start of the internal combustion engine,
crank angle detection means for outputting crank angle signals at predetermined crank angles;
cam angle detection means for outputting cam angle signals at a plurality of cam angles for cylinder discriminations;
and
real advance angle position calculation means for calculating the real advance angle position of said camshaft phase on the basis of said crank angle signals and said cam angle signals,
wherein the improvement comprises:
failure detection means for detecting at least one of lock failure and the lock release failure of said lock means on the basis of at least one of the magnitude of the dispersion of the advance angles of said cam angle signals with respect to said crank angle signals and the real advance angle position of said camshaft phase.

5 more elements

A variable valve timing control system for an internal combustion engine, comprising:

a variable valve timing adjuster mounted on at least one of the intake valve and the exhaust valve of the internal combustion engine, for making the valve timing variable, said variable valve timing adjuster including a lock mechanism for locking the valve timing at a predetermined phase when the variable valve timing control is not made, wherein said lock mechanism and said variable valve timing adjuster are driven by a hydraulic control valve,
wherein the improvement comprises:
lock release control means for controlling a hydraulic control valve of said hydraulic control circuit, during the lock release control of said lock mechanism, so that an oil pressure may be applied to said lock mechanism in a lock release direction;
and
lock release judgment means for judging whether or not the lock of said lock mechanism is released,
wherein said lock release control means drives said hydraulic control valve in a drive pattern for an abnormal condition cancel control and then makes again the lock release control, when it is judged that the lock is not released after the end of the lock release control.

3 more elements

Dependencies are inferred from the claim text.

Variable valve timing control system

Life of this patent

Variable valve timing control system

Life of this patent

Abstract

Claims41