The present invention provides a controlled-compression direct-power-cycle engine for performing the direct-power-cycle, wherein the air is compressed with three compression processes and cooled to a controlled temperature before ignition, the
engine power output is controlled by both the compressor-transmission and the
servo-intake-valve; the three compression processes are the initial-compression-process, the intermediate-compression-process, the final-compression-process, wherein, the initial-compression-process is performed by the
turbocharger, the intermediate-compressor-process is performed by a screw type compressor, a rotary type compressor, or a scroll type intermediate-compressor, the final-compression-process is performed by the pistons of the
combustion chambers; said intermediate-compressor is coupled to the compressor-transmission for adjusting the compression-capacity according to the instruction signals from the
engine control unit, which computes the required compression-capacity by the user's
power demand and the pressure in the cooling tank; said final-compression-process adjusts the actual-pressure-ratio with the actuation-time of the
servo-intake-valve; said
servo-intake-valve is opened for 5-60 degree of
crankshaft rotation and is shut at a point between 90 degree BTC and 10 degree BTC according to instruction signals from the
engine control unit; wherein the compressor-transmission is set to provide a higher
airflow and said servo-intake-valve is shut at an earlier
crankshaft reference angle to increase the actual-pressure-ratio of the final-compression-process for operating the direct-power-cycle at a
high power output, whereas the compressor-transmission is set to provide a lower
airflow and said servo-intake-valve is shut at a later
crankshaft reference angle to decrease the actual-pressure-ratio of the final-compression-process for operating the direct-power-cycle at a lower
power output.