Variable camshaft timing system utilizing square-edged spool valve
Number of patents in Portfolio can not be more than 2000
United States of America Patent
Stats
-
May 4, 1993
Grant Date -
N/A
app pub date -
May 15, 1992
filing date -
May 15, 1992
priority date (Note) -
In Force
status (Latency Note)
Importance
Abstract
A camshaft (126) has a vane (160) secured to an end thereof for non-osciling rotation therewith. The camshaft also carries a sprocket (132) which can rotate with the camshaft but which is oscillatable with respect to the camshaft. The vane has opposed lobes (160a, 160b) which are received in opposed recesses (132a, 132b), respectively, of the sprocket. The recesses have greater circumferential extent than the lobes to permit the vane and sprocket to oscillate with respect to one another, and thereby permit the camshaft to change in phase relative to a crankshaft whose phase relative to the sprocket is fixed by virtue of a chain drive extending therebetween. The camshaft tends to change in reaction to pulses which it experiences during its normal operation, and it is permitted to change only in a given direction, either to advance or retard, by selectively blocking or permitting the flow of hydraulic fluid, preferably engine oil, through the return lines (194, 196) from the recesses by controlling the position of a spool (200) within a valve body (198) of a control valve in response to a signal indicative of an engine operating condition from an engine control unit (208). The spool contains square-edged lands (254, 256) which prevent hydraulic fluid contamination from wedging between the valve body and the spool itself.
First Claim
Other Claims data not available