| 摘要 |
The invention relates to a method for estimating the supercharging pressure of a gas flowing in a supply duct having a geometrical section (SC) in a supercharged Diesel engine, comprising an inlet flap having an effective section (SE) depending on the position (%F) thereof, and a manifold. The method comprises: determining the supercharging pressure from the so-called "pressure loss" formula PS1 = PC + (QV2.R,TV)/(2.PC.SC2), CP(%F), where R is the specific constant of the gas, PC is the gas pressure in the manifold, QV is the gas flow rate through the inlet flap, TV is the gas temperature in the supply duct and CP is a correction coefficient; comparing the ratio PC/PS1 to a threshold; if the ratio is higher than set threshold, setting PS1 as supercharging pressure, otherwise proceeding with the following steps: determining the supercharging pressure from the so-called "Barré de Saint Venant" formula PS2 = PC.[ 1/2+( 1/4 + (QV2.R.TV)/(SE(%F)2.PC2).(G-1)/{2.G) )1/2] where G is the ratio between the caloric capacity under a constant pressure and the caloric capacity at a constant volume of said gas; comparing the ratio PC/PS2 to a threshold; if the ratio is lower than said threshold, setting PS2 as the supercharging pressure, otherwise proceeding with the following step: determining the supercharging pressure from the so-called "Barré de Saint Venant at critical rate" formula PS3 = QV.(R.TV)1/2 / [ SE(%F).G1/2 ]. { 2/(G+1) ) {G+1)/2 (G-1))] and setting PS3 as the supercharging pressure. |
