Patent ID: 6129060
Filing Date: 2000-10-10
Classification: F01L

Abstract:
A camshaft phase changing apparatus for an internal combustion engine, comprising:a rotary body adapted to be rotated by the engine in synchronism therewith;a camshaft rotatable about its axis together with the rotary body;a chamber formed between the camshaft and the rotary body;a cam phaser positioned in the chambers wherein the cam phaser adjusts a rotational phase relationship between the rotary body and the camshaft and partitions the chamber into a first hydraulic chamber and a second hydraulic chamber, wherein the cam phaser is movable between the first and second hydraulic chambers based on applied pressure differences therebetween to adjust the rotational phase relationship between the rotary body and the camshaft;a hydraulic circuit having:a hydraulic source;a hydraulic supply passage led from the hydraulic source;a pair of first and second hydraulic passages, the first hydraulic passage communicating with The first hydraulic chamber and the second hydraulic passage communicating with the second hydraulic chamber; anda hydraulic drain passage that drains pressurized working oil from one of the first and second hydraulic chambers to the hydraulic source,wherein the hydraulic circuit supplies the pressurized working oil to one of the first and second hydraulic chambers from the hydraulic source and drains the pressurized working oil from the other ot the first and second hydraulic chambers to the hydraulic source depending on an engine driving condition;a determinator that determines the engine driving condition; anda control valve interposed in the hydraulic circuit, the control valve controlling fluid supply to or drainage from the first hydraulic chamber through the first hydraulic passage and fluid drainage from or supply to the second hydraulic passage through the second hydraulic supply passage according to the engine driving condition,wherein the control valve has a first port and a second port, the first port connecting the hydraulic drain passage to one of the first and second hydraulic passages, and the second port connecting the hydraulic supply passage to the other of the first and second hydraulic passages,wherein the hydraulic drain passage includes a pair of first and second hydraulic drain passages linked to the hydraulic source and wherein the control valve includes:a valve seat;an electromagnetic actuator;a spool valve body having a valve hole formed in a peripheral wall of the valve seat, the spool valve body being slidably disposed in the valve hole, wherein the first port of the control valve includes a third port and a fourth port, both of the third port and the fourth port being formed on the peripheral wall of the valve seat, the third port connecting the first hydraulic drain passage to the first hydraulic passage and the fourth port connecting the second hydraulic drain passage to the second hydraulic passage;a fifth port connecting the first hydraulic passage to one of the hydraulic supply passage and the first hydraulic drain passage; anda sixth port connecting the second hydraulic passage to one of the hydraulic supply passage and the second hydraulic drain passage, the spool valve body having first, second, and third valve parts for integrally varying the orifice cross sectional areas of the second, third, and fourth ports when the cam phaser is moved between the pair of the first and second hydraulic chambers to adjust the rotational phase relationship between the rotary body and the camshaft,wherein the second port is formed as an annular groove on the peripheral wall of the valve seat, and an axial length of the first valve part is slightly shorter than a width of the annular groove of the second port taken along the direction of the axial length of the first valve part.