FEV, a developer of advanced powertrain and vehicle technologies, exhibited a two-step variable compression ratio (VCR) mechanism for the first time in the United States at the 2008 SAE World Congress recently.
This VCR mechanism was developed for both gasoline and diesel engines.
The mechanism dynamically adjusts the center of the bore at the top end of the conrod, thereby achieving compression ratios of 14:1-17:1, depending on configuration, increasing engine efficiency and reducing nitrogen oxide emissions. Key to the system is its ability to be integrated into existing engine designs due to its carryover piston and pin design. Other benefits derived from the ability to adjust the compression ratio include improved cold startability and the potential to optimize performance while utilizing alternative fuels.
The system currently supports peak cylinder pressures of 180 bar and is presently completing durability testing.