Controlling engine fuel injection

Claim 2

An engine fuel injection control method, cyclically repeating the following steps: (A) measuring engine operating parameters including the throttle valve angle (Tth) and the engine speed (N), (B) estimating the air flow (Qap) into the cylinder on the basis of said measured operating parameters (Tth, N) and by means of a table holding data once determined for the engine, and (C) controlling the fuel quantity according to the estimated air flow (Qap) into the cylinder, characterized in that step (B) comprises the following substeps: (a) calculating the estimated manifold pressure (PM (i)) from the manifold pressure (PM (i-1)) calculated in a previous cycle of the method and from the difference between the air flow (Qat (i-1)) passing through the throttle valve and the air flow (Qap (i-1)) into the cylinder both having been estimated in a previous cycle of the method, (b) estimating the air flow (Qap (i)) into the cylinder and the air flow (Qat (i)) passing through the throttle valve from the calculated manifold pressure (PM (i)), the measured throttle valve angle (Tth) and the measured engine speed (N) by means of said table.

Claim 3

The method of claim 1, characterized in that a relationship between engine operating parameters and the accurately measured air flow is experimentally determined over the operating range of the engine at a central location for many engines and then stored in said table associated with the measured engine.

Claim 4

The method of claim 2, characterized in that said table comprises a first look-up table and a second look-up table, wherein said step of experimentally determining said relationship comprises the substep of experimentally measuring the manifold pressure, the engine speed and the air flow into the cylinder accurately and placing the relationship between the measured values in said first look-up table, and further experimentally measuring the manifold pressure, the throttle angle and the air flow passing through the throttle valve accurately and placing the relationship between these values in said second look-up table.

Claim 5

The method of claim 2, characterized in that the engine operating parameters include at least one of the intake manifold pressure, the intake air temperature, the engine speed and the throttle angle.

Claim 6

The method of claim 2, characterized in that the step of experimentally determining said relationship comprises the substeps of experimentally measuring the manifold pressure, the engine speed and the air flow into a cylinder accurately and placing the relationship between these values into said table.

Claim 9

A fuel injection control apparatus for an internal combustion engine, comprising: non-volatile memory means (12, 14) holding data once determined for the engine in the form of a table, means for measuring engine operating parameters including the throttle valve angle (Tth) and the engine speed (N), means (11...14) for estimating the air flow (Qap) into the cylinder on the basis of the measured operating parameters (Tth, N) and by means of the data stored in said memory means (12, 14), and means (15) for controlling the fuel quantity in accordance with the estimated air flow (Qap), characterized in that said means (11...14) for estimating the air flow (Qap) includes means (13) for calculating the estimated manifold pressure (PM(i)) from the manifold pressure (PM-(i-1)) previously calculated and from the difference between the air flow (Qat(i-1)) passing through the throttle valve and the air flow (Qap(i-1)) into the cylinder both having been previously estimated, and means (14) for estimating the air flow (Qap(i)) into the cylinder and the air flow (Qat(i)) passing through the throttle valve from the calculated manifold pressure (PM(i)), the measured throttle valve angle (Tth) and the measured engine speed (N) on the basis of the data stored in said memory means (12, 14).

Claim 10

A fuel injection control apparatus for an internal combustion engine, comprising: non-volatile memory means (12, 14) holding data once determined for the engine in the form of a table, means for measuring engine operating parameters including the throttle valve angle (Tth) and the engine speed (N), means (11...14) for estimating the air flow (Qap) into the cylinder on the basis of the measured operating parameters (Tth, N) and by means of the data stored in said memory means (12, 14), and means (15) for controlling the fuel quantity in accordance with the estimated air flow (Qap), characterized in that said means (11...14) for estimating the air flow (Qap) includes means (13) for calculating the estimated manifold pressure (PM(i)) from the manifold pressure (PM-(i-1)) previously calculated and from the difference between the air flow (Qat(i-1)) passing through the throttle valve and the air flow (Qap(i-1)) into the cylinder both having been previously estimated, and means (14) for estimating the air flow (Qap(i)) into the cylinder and the air flow (Qat(i)) passing through the throttle valve from the calculated manifold pressure (PM(i)), the measured throttle valve angle (Tth) and the measured engine speed (N) on the basis of the data stored in said memory means (12, 14).

Claim 11

The apparatus of claim 8, characterized in that said data is the relationship between engine operating parameters and the accurately measured air flow experimentally determined over the operating range of the engine at a central location for many engines and then stored in said memory means (12, 14) associated with the measured engine.

Claim 12

The apparatus of claim 9, characterized in that said memory means comprises a first look-up table (14), holding the experimentally determined relationship between the accurately measured manifold pressure, the engine speed and the air flow into the cylinder, and a second look-up table (12), holding the experimentally determined relationship between the accurately measured manifold pressure, the throttle angle and the air flow passing through the throttle valve.

Claim 13

The apparatus of claim 9, characterized in that the engine operating parameters include at least one of the intake manifold pressure, the intake air temperature, the engine speed and the throttle angle.

Claim 14

The apparatus of claim 9, characterized in that said memory means (12, 14) hold the accurately measured relationship between the manifold pressure, the engine speed and the air flow into a cylinder.