Patent ID: 6202610
Filing Date: 2001-03-20
Classification: F01L

Abstract:
A valve operating control system for an internal combustion engine having a low-speed cam and a high-speed cam, comprisingan oil pump;a cam switching type, first valve operating characteristic changing mechanism;a first hydraulic pressure control valve, wherein hydraulic pressure is supplied from said oil pump through said first hydraulic pressure control valve to said first valve operating characteristic changing mechanism;a cam-phase changing type, second valve operating characteristic changing mechanism;a second hydraulic pressure control valve, wherein the hydraulic pressure is supplied from said oil pump through said second hydraulic pressure control valve to said second valve operating characteristic changing mechanism;wherein said first valve operating characteristic changing mechanism selects said low-speed cam to establish a low-speed valve timing, when no hydraulic pressure is supplied from said first hydraulic pressure control valve, and selects said high-speed cam to establish a high-speed valve timing, when the hydraulic pressure is supplied,wherein said second valve operating characteristic changing mechanism includes an advancing chamber and a retarding chamber, said second valve operating characteristic changing mechanism changing the cam phase, when the hydraulic pressure is supplied selectively to said advancing chamber or said retarding chamber,and wherein when said first valve operating characteristic changing mechanism establishes the high-speed valve timing and said second valve operating characteristic changing mechanism sets the cam phase in a most-displaced basic position, said second hydraulic pressure control valve closes both of said advancing chamber and said retarding chamber, and is maintained in a neutral position in which it cuts off hydraulic pressure supplied from said oil pump.