Patent ID: 6928967

Claim:
Electromagnetic hydraulic valve, in particular a proportional valve for controlling a device for adjusting a rotation angle of a camshaft relative to a crankshaft in an internal combustion engine, comprising: the hydraulic valve ( 1 ) includes a cylindrical hollow electromagnet ( 2 ) with an armature ( 3 ) which moves axially therein, and a cylindrical valve housing ( 4 ) with an axial bore ( 5 ), and a piston valve ( 6 ) located therein, the piston valve ( 6 ), formed as a hollow piston, is positioned by the armature ( 3 ) of the electromagnet ( 2 ) through a power interaction and can be moved axially in the axial bore ( 5 ) of the valve housing ( 4 ) against a restoring force of a compression spring ( 7 ), the valve housing ( 4 ) has on a periphery thereof a plurality of annular grooves ( 8 , 9 , 10 ) spaced apart axially from each other, in which several radial openings ( 11 , 12 , 13 ) are located, which are distributed evenly and open into the axial bore ( 5 ) of valve housing ( 4 ), the hydraulic valve ( 1 ) has a fluid connection through the radial openings ( 11 , 12 , 13 ) as well as through an open side of the axial bore ( 5 ) in the valve housing ( 4 ) with at least one pressure connection (P), one tank connection (T), and two consumer connections (A, B), the piston valve ( 6 ) has at least two circular control sections ( 14 , 15 ), which alternatively connect, through the axial displacement of piston valve ( 6 ), the pressure connection (P) and the tank connection (T) with one of the consumer connections (A, B), the control sections ( 14 , 15 ) and connecting webs ( 16 , 17 ) which are located between the radial openings ( 11 , 12 , 13 ) of each consumer connection (A, B), provide a guide for the piston valve ( 6 ) within the axial bore ( 5 ) of valve housing ( 4 ), the radial openings ( 11 , 12 , 13 ) which open into the axial bore ( 5 ) of valve housing ( 4 ) comprise a generally quadrangular cross section window, the cross section surfaces ( 18 , 19 ), released by the control sections ( 14 , 15 ) of piston valve ( 6 ) form circular segments and can be changed through axial movements of piston valve ( 6 ) such that, a flow of hydraulic medium through the radial openings ( 11 , 12 , 13 ) is in all positions of piston valve ( 6 ) linear to a position of the armature ( 3 ) of the electromagnet ( 2 ).