Patent ID: 6523513
Filing Date: 2003-02-25
Classification: F01L

Abstract:
A camshaft timing device for an internal combustion engine having a camshaft driven by a drive shaft by way of a camshaft drive mounted co-axially onto said camshaft, a clamping screw extending through said driveshaft and into a central openings in said camshaft for engaging said drive with said camshaft, said clamping screw having a cylindrical opening providing for a valve housing, a valve spool axially movably disposed in said cylindrical opening, a control spring disposed in said cylindrical opening so as to bias said valve spool toward an end position, a valve spool actuating drive disposed on said clamping screw for moving said valve spool against the force of said control spring, said valve housing having two axially spaced control openings for supplying hydraulic fluid to, and releasing it from, a timing motor of said timing device, said valve spool having two spaced annular webs sealingly disposed in said cylindrical opening at a distance from each other corresponding essentially to the spacing between said control openings and forming therebetween a pressurized fluid supply chamber, which is in communication with a fluid supply bore in said camshaft, said spool including fluid release chambers at opposite sides of said annular webs which fluid release chambers are in communication with a fluid drain passage by way of a connecting passage extending centrally through said valve spool, said valve spool being movable by said actuating drive against the force of said spring to place one of said control openings into communication with said pressurized fluid supply chamber for supplying pressurized fluid to said camshaft drive through said one control opening and the other of said control openings in communication with one of said pressure release chambers for releasing fluid from said camshaft drive to said drain passage and said valve spool being movable by said spring in the opposite direction to place the other of said control openings into communication with said pressurized fluid supply chamber for supplying pressurized fluid to said camshaft drive through said other control opening and to place said one control opening in communication with other pressure release chamber for discharging fluid from said camshaft drive through said one control opening for controlling operation of said camshaft drive.