Internal combustion engine with at least one hollow-head valve

An internal combustion engine, comprising:

• at least one cylinder;
• at least one hollow-head valve including a valve shaft and a valve head;
• a valve shaft guide circumferentially surrounding a portion of the valve shaft, the valve shaft guide having a first axial end remote from the valve head and a second axial end proximal to the valve head;
• a valve shaft seal including at least two lips, a first portion of the valve shaft seal externally surrounding and secured to the first axial end of the valve shaft guide, and a second portion of the valve shaft seal surrounding and contacting the valve shaft via the at least two lips;
• and
• at least one valve seat ring on which the valve head sealingly lies when the at least one hollow-head valve is closed;
• wherein an intermediate space configured to receive and retain oil is defined between the valve shaft and the valve shaft guide such that the valve shaft is arranged in the valve shaft guide with a radial play of 40 μm to 80 μm;
• wherein the at least one valve seat ring is composed of a sintered metal including infiltrated copper;
• wherein the valve shaft includes one of a chromium-containing coating and a boron carbide-containing coating;
• and
• wherein the valve shaft has a conical shape that narrows towards a transition to the valve head and is configured to thermally expand to have a cylindrical shape during operation of the internal combustion engine.

An internal combustion engine, comprising:

• at least one cylinder;
• at least one hollow-head valve including a valve shaft and a valve head, the valve shaft having a first end connected to the valve head and a second end disposed opposite the valve head;
• a valve shaft guide circumferentially surrounding a portion of the valve shaft;
• a valve shaft seal including at least two lips;
• and
• at least one valve seat ring on which the valve head sealingly lies when the at least one hollow-head valve is closed;
• wherein an intermediate space configured to receive and retain oil is defined between the valve shaft and the valve shaft guide;
• wherein the at least one valve seat ring is composed of a sintered metal including infiltrated copper;
• wherein the valve shaft includes one of a chromium-containing coating and a boron carbide-containing coating;
• and
• wherein an external diameter of the valve shaft at a transition from the first end of the valve shaft to the valve head is smaller than an external diameter of the valve shaft at the second end.