Hydraulic camshaft phaser

1. A hydraulic camshaft phaser for an internal combustion engine, comprising:

an outer rotor; and

an inner rotor, the outer rotor and the inner rotor being rotationally adjustable and arranged concentrically about a common axis of rotation;

at least one hydraulic chamber being formed between the outer rotor and the inner rotor, into which hydraulic chamber at least one connected vane extends from each of the outer rotor and the inner rotor, thereby dividing the hydraulic chamber into at least one pressure chamber pair formed by two pressure chambers;

the inner rotor having a circular opening extending concentrically along the axis of rotation, a sealing portion being formed on an inner surface of the circular opening between two axial faces of the inner rotor, the circular opening having a larger cross-sectional area on both sides of the sealing portion than in the sealing portion, the inner rotor being a sintered part, the sealing portion of the inner rotor being calibrated.

2. The hydraulic camshaft phaser as recited in claim 1 wherein a core assembly is disposed in the sealing portion of the opening.

3. The hydraulic camshaft phaser as recited in claim 2 wherein the core assembly includes a central valve.

4. The hydraulic camshaft phaser as recited in claim 2 wherein a clearance fit is provided between the core assembly and the sealing portion.

5. The hydraulic camshaft phaser as recited in claim 1 wherein the inner rotor and the at least one vane connected to the inner rotor form an integral component.

6. The hydraulic camshaft phaser as recited in claim 1 wherein the sealing portion has a constant inside diameter.

7. The hydraulic camshaft phaser as recited in claim 1 wherein the sealing portion is disposed symmetrically between the axial faces of the inner rotor.

8. The hydraulic camshaft phaser as recited in claim 1 wherein the circular opening has equal diameters on both sides of the sealing portion.