Variable compression ratio has for decades been a recognized method of improving the efficiency of engines, especially for IC engines running at lower and varying operating loads. Several attempts have for various reasons failed. Foremost, if not for all proposals, because they were based on modifications of the conventional piston rod system. Consequently, they became too complicated, too heavy, too large and mostly, too expensive.
Changing challenges to become options by eliminating the cause of the issue, often seems better than fighting the problems. The innovation of LRT has released the design of a practical, robust and fuel-efficient VCR solution. The linear moving piston rods run through coaxial worm gears, which by turning the rods can elevate the rods up and down on the yoke’s furnished threads, thereby changing the top dead position of the piston.
The compression ratio can be adjusted automatically at run-time between 7:1 and 15.4:1, depending on the engine’s actual load. When cruising, a car engine works at an average of 15 – 25% of full effect. Within this range the compression ratio will stay at 15,4:1, and the engine efficiency remains high. The VCR mechanism is moving only when the compression rate is changed, otherwise it will remain passive.