An additional approach for reducing the formation of carbon deposits on the intake valves is to increase the intake valve temperature, at least temporarily, since, surprisingly, it was found that any carbon deposits possibly present are removed at temperatures above 380° C.
To this end, the intake valve unit, which comprises, among other components, the intake valves and the valve stem guide, is designed with means that hinder heat dissipation in such a way that increased surface temperatures of more than 380° C develop at least in the area of the neck of the intake valves in at least one predetermined region of the load characteristic diagram of the internal combustion engine.
At these temperatures, carbon deposits on the intake valves are removed. This region of the characteristic diagram occurs, for example, at speeds over 3,000 rpm, and in that speed range. extends essentially to full load. Even if the internal combustion engine is not operated most of the time in the region during normal driving operation of a motor vehicle, nevertheless, carbon deposits that could adversely affect the operation of the internal combustion engine cannot build up, since their removal in the shaded region of the characteristic diagram occurs very quickly. For example, operation of the internal combustion engine in this region of the characteristic diagram for a period of, for example, 20 min., is sufficient to remove even a thick layer of carbon deposits. In other words, a routine expressway trip cleans the intake valves sufficiently.
En gros, time to beat the crap out of your car for a good cause.