JPH04153546A - Fuel characteristic judging device - Google Patents

Abstract

PURPOSE:To correctly judge the fuel characteristic such as fractional distillation point by representing the composition of the inspected fuel by a mixed fuel model consisting of at least four kinds of single component fuel having different fractional distillation point. CONSTITUTION:A means 102 sets the ratio of each fuel component of a mixed fuel model consisting of at least four kinds of single component fuel having different fractional distillation point. A means 103 calculates the saturated vapor pressure of the mixed fuel model based on the set of the means 102, and a means 104 calculates the physical property value equal to that of the inspected fuel in the mixed fuel model based on the calculation result of the means 103. Then, a means 105 compares the detection value of the physical property value by the means 101 and the calculation value of the physical property value by the means 104, and a means 106 corrects the mixing ratio of each single component fuel so that the comparison result accords. Accordingly, the fuel properties such as fractional distillation point can be judged correctly, and the control precision in the fuel feed quantity control under the use of the fuel behavior model can be improved drastically.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a fuel property determining device suitable for determining the fractional distillation properties of hydrocarbon fuel such as gasoline.

(Prior art) In order to control the amount of fuel supplied to an internal engine with high precision, the amount of fuel adhering to the wall of the intake pipe and the amount of fuel evaporating within the intake pipe are used as state variables to control the amount of fuel flowing into the engine cylinder. After setting up a fuel band movement model that describes the behavior of A fuel injection amount control device that determines the amount of fuel injection has been proposed (see Japanese Patent Laid-Open No. 1-271623).

(Problem to be Solved by the Invention) By the way, when calculating the required amount of fuel from a fuel behavior model as described above, calculation of the fuel state amount may affect the actual amount of fuel deposited and vaporized in the intake system. It is necessary to accurately determine the fractionation properties of fuel.

However, with conventional methods, the accuracy of detecting fuel properties was low, such as by representing the fuel properties only by the detected octane number and specific gravity, so there was a natural limit to the control accuracy of the final fuel supply amount. Particularly during transient periods, a deviation from the required amount of furnace material occurs, resulting in deterioration of operability and exhaust emissions.

The present invention was made by focusing on these problems.
The purpose is to determine the fuel properties by representing the composition of the test fuel using a fuel model consisting of four or more types of single component fuel.

(Means for Solving the Problem) In order to achieve the above object, the present invention uses a means 101 for detecting predetermined physical property values of the test fuel, as shown in FIG.
means 102 for setting the ratio of each fuel component of a mixed fuel model consisting of i types of single fuel components having different fractionation points (i≧4); and saturated steam of the mixed fuel model based on the settings. means for calculating the pressure] 03; means 104 for calculating the same physical property values as the test fuel for the mixed fuel model based on the calculation results; and means 105 for comparing the detected values of the physical property values with the calculated values; and means 106 for modifying the mixing ratio of each single fuel component so that the comparison results match.

(Function) Four or more types of fuel with different fractionation points in any proportion'
When forming a Ch mixed fuel model, if the predetermined physical property values in the mixed fuel model, such as fractional distillation amount and saturated vapor pressure, match the physical property values of the test fuel such as gasoline, the mixture The fuel properties including fractionation characteristics of the fuel model match well with those of the tested fuel.

Therefore, based on the configuration of the present invention, it is possible to accurately know the fuel vaporization amount, which greatly influences control accuracy, for example, in fuel supply amount control using a fuel behavior model.

(Example) Below is a second example of determining fuel properties from a comparison of fractionation amounts using a fuel model consisting of four types of single component fuels.
This will be explained with reference to the flowchart shown in the figure.

In this case, first, a fuel model is set in which four types of single-component fuels with different fractionation points are mixed at an arbitrary volume ratio,
The saturated vapor pressure Pv(i) of each component is calculated from the following equation. Note that i indicates the type of single-component fuel, and in this case, i=1 to 4.

Pv)”Po-expfK(i)<1/Tfv(i)
1/T)1...(1) where Po: atmospheric pressure, Tfν(1): boiling point of each component, and K(i): constant for each component.

Next, based on the saturated vapor pressure of each component obtained in this way, the saturated vapor pressure Pv of the entire mixed fuel is calculated from the following equation.

Pv=ΣPv(i) −Rx(i)
=12) where Rx(i) is the molar fraction of each component.

Once the saturated vapor pressure Pv has been determined for any mixed fuel model in this way, the next step is to calculate the fractional distillation amount V from the well-known equation of state based on this, and Compare with the fractional distillation amount Vo for fuel.

In this comparison, if ■ does not match Vo, V
=V o The process of returning to the beginning, resetting the mixing ratio of each component in the fuel model to a different ratio, and calculating the fractional distillation amount ■ is repeated.

As a result, if the calculated value V of the fractionation amount and the detected value vO match, other physical property values of the test fuel such as specific gravity, specific heat, viscosity coefficient, thermal conductivity, diffusion coefficient, etc. Calculate and end the process.

In this way, the physical property values (in this case, the fractional distillation amount) of a mixed fuel model consisting of four or more single component fuels are determined.
If the mixing ratio is set so that the ratio matches that of the test fuel, the fuel properties including the fractionation properties of the fuel model based on that mixing ratio will match those of the test fuel very well8. is a fractionation characteristic diagram showing the evaluation results, where the solid line in the figure shows the actual fractionation characteristics of gasoline, and the plotted line shows the calculation results according to the present invention.

Figure 3 shows the evaluation results for standard gasoline on the market, Figure 4 shows the evaluation results for the lightest gasoline, and Figure 15 shows the evaluation results for the heaviest gasoline. In each case, the calculated values are close to the actual fractionation characteristics. It can be seen that they match.

Note that Figure 6 shows the evaluation results when one type of single-component fuel is used as a model, and Figure 7 shows the evaluation results when a mixed fuel of two types of single-component fuel is used as a model. The results do not necessarily match the actual values and do not have sufficient accuracy. For this reason, the applicant has set the number of types of single component fuel to four or more.

(Effects of the Invention) As explained above, according to the present invention, the composition and fuel properties of the test fuel can be accurately represented by a mixed fuel model consisting of four or more single component fuels with different fractional distillations and α. Therefore, it is possible to significantly improve control accuracy in fuel supply amount control using a fuel behavior model, for example.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing the configuration of the present invention, Fig. 2 is a flow chart showing the contents of calculation processing according to an embodiment of the present invention, and Figs. 3 to 7 show actual fractional characteristics and their calculated values, respectively. It is a characteristic line diagram showing the relationship between. 101... Physical property value detection means of test fuel, 102...
Mixing ratio setting means for fuel model, 103...Saturated vapor pressure calculation means, 104...Physical property value calculation means for fuel model, 105...
・Physical property value comparison means, 106...-Mixing ratio correction means. Figure 1 Figure 2 DISTILRTC ~ 0/

Claims (1)

[Claims] means for detecting a predetermined physical property value of the test fuel; and means for setting the ratio of each fuel component in a mixed fuel model consisting of i types (where i≧4) of single fuel components having different fractionation points. , means for calculating the saturated vapor pressure of the mixed fuel model based on the settings, means for calculating the same physical property values as the test fuel for the mixed fuel model based on the calculation results, and calculating the detected values of the physical property values. a means of comparing the values;
A fuel property determination device comprising: means for modifying the mixing ratio of each single fuel component so that the comparison results match.