Cam shaft phase setter comprising a control valve for hydraulically adjusting the phase position of a cam shaft

A cam shaft phase setter comprising:

• (a) a control valve for controlling feeding and draining of a hydraulic fluid into and out of pressure chambers which serve to adjust the rotational angular position of a cam shaft relative to a crankshaft of an internal combustion engine,
• (b) the pressure chambers comprising a first chamber and a second chamber, one of the first chamber and second chamber for adjusting the cam shaft to lead relative to the crankshaft when the pressure is applied, and the other of the first chamber and the second chamber for adjusting the cam shaft to trail when the pressure is applied,
• (c) the phase position of the cam shaft being set by introducing the pressurised fluid by the control valve into either the first chamber or the second chamber, and connecting the other type of pressure chambers in each case to a low-pressure side of the fluid,
• (d) the control valve comprising:
• (d1) a valve housing connectable, rotationally fixed, to the cam shaft or being formed by the cam shaft, such that when the cam shaft rotates, the control valve rotates together with the cam shaft, the valve housing comprising a first operating port for feeding said pressure fluid to the first chamber, a second operating port for feeding said pressure fluid to the second chamber, the second operating port being axially spaced from the first operating port, and a reservoir port for draining the fluid to a reservoir provided on the low-pressure side of the fluid,
• (d2) a valve piston which can be axially adjusted back and forth in the valve housing between a first piston position and a second piston position and comprises an axial hollow space, a piston inlet for introducing fluid into the hollow space, and a piston outlet which leads out of the hollow space,
• (d3) the piston outlet being connected to the first operating port in the first piston position and separated from the first operating port in the second piston position, the piston outlet being connected to the second operating port in the second piston position and separated from the second operating port in the first piston position, and
• (e) the cam shaft phase setter further comprising an actuating unit, coupled to the valve piston, for axially adjusting the valve piston,
• (f) wherein the valve piston comprises a recess which connects the first operation port of the valve housing to the reservoir port in the first position of the valve piston, and
• (g) wherein behind the piston outlet, as viewed in the axial direction from the recess, a further axially extending recess is formed on the outer circumference of the valve piston, the further radial recess connected to the reservoir in the first position of the valve piston.