Patent ID: 7506622
Filing Date: 2009-03-24
Classification: F01L,Y10T

Abstract:
1. A valve timing control system installed in a drive transmission system that transmits a drive force from a drive shaft of an internal combustion engine to a follower shaft, which opens and closes at least one of an intake valve and an exhaust valve of the internal combustion engine, so that the valve timing control system adjusts opening and closing timing of the at least one of the intake valve and the exhaust valve, the valve timing control system comprising: a housing that is rotated together with one of the drive shaft and the follower shaft and has at least three receiving chambers, each of which is formed within a predetermined angular range in a rotational direction; a vane rotor that is rotated together with the other one of the drive shaft and the follower shaft and has at least three vanes, each of which is received in a corresponding one of the at least three receiving chambers to partition the receiving chamber into a corresponding retard chamber and a corresponding advance chamber, wherein the vane rotor is driven to rotate in a corresponding one of a retard side and an advance side relative to the housing by a pressure of working fluid in a corresponding one of each retard chamber and each advance chamber of the at least three receiving chambers, so that a relative phase of the vane rotor relative to the housing is controlled; a passage arrangement that includes: at least one phase check valve that is installed in at least one predetermined passage, respectively, which is selected from the group of at least three retard passages and the group of at least three advance passages, wherein each phase check valve limits the working fluid to flow from a corresponding check valve connecting chamber, which is a corresponding one of the retard chambers and the advance chambers of the at least three receiving chambers connected to the phase check valve, toward the fluid source, while the phase check valve permits the working fluid to flow from the fluid source to the corresponding check valve connecting chamber; and at least one drain control valve, each of which is driven by a pilot pressure exerted by the working fluid from the fluid source and is installed in a corresponding one of at least one fluid discharge passage, which is provided separately from the group of at least three retard passages and the group of at least three advance passages to discharge the working fluid from the check valve connecting chamber that is associated with a corresponding one of the at least one phase check valve, wherein: each drain control valve blocks the corresponding fluid discharge passage when the working fluid is supplied from the fluid source to the check valve connecting chamber associated with the corresponding one of the at least one phase check valve to rotate the vane rotor in a corresponding one of the retard side and the advance side relative to the housing; and the drain control valve opens the corresponding fluid discharge passage when the working fluid is discharged from the check valve connecting chamber associated with the corresponding one of the at least one phase check valve to rotate the vane rotor in the other one of the retard side and the advance side relative to the housing; and