Patent ID: 6935290
Filing Date: 2005-08-30
Classification: F01L,Y10T

Abstract:
1. A variable cam timing phaser for an internal combustion engine with at least one camshaft comprising: a housing having an outer circumference for accepting drive force; a rotor for connection to a camshaft, coaxially located within the housing, the housing having at least one chamber and the rotor having at least one vane dividing the chamber into at least one advance chamber and a retard chamber, the vane being capable of rotation to shift the relative angular position of the housing and the rotor; a spool valve comprising a spool having a plurality of lands slidably mounted within a bore in the rotor, the spool in fluid communication with a supply of hydraulic fluid; a plurality of passages connecting the advance chamber and the retard chamber to the spool valve; and a ring-shaped reservoir defined within the bore by an oil dam and at least one of the spool lands; wherein the spool has a first position in which the advance chamber or the retard chamber is in fluid communication with the supply of hydraulic fluid and the other chamber is exhausting hydraulic fluid to the ring-shaped reservoir and a second position in which the advance chamber or the retard chamber is in fluid communication with the supply of hydraulic fluid and the other chamber is in fluid communication with the ring-shaped reservoir, such that when a torque reversal occurs, hydraulic fluid pooled in the ring-shaped reservoir is drawn into the advance chamber or retard chamber when the spool is in the second position.