DEVICE FOR OBTAINING A VALUE CORRESPONDING TO THE ALCOHOL CONCENTRATION OF INTERNAL COMBUSTION ENGINE FUEL

摘要

The device provided obtains (at step 620) the pressure in the cylinder P(?a) at a prescribed time (BTDC ?a°) in the period from after the start of the compression stroke until the combustion of the gaseous mixture starts, based on the output of a cylinder pressure sensor.  Then the internal energy U(?a) of the gas at said prescribed time is calculated (at step 630) on the basis of the product of the pressure in the cylinder P(?a) and the combustion chamber volume V(?a) at said prescribed time.  Then the actual alcohol concentration of the fuel is obtained (at step 640) on the basis of the relationship indicating that the alcohol concentration of the fuel is lower when the internal energy U(?a) is larger.