Method for estimating a top dead centre for a high-pressure pump of a fuel injection system in an automotive vehicle engine

A method for estimating an angular position of top dead center (25) for a high-pressure fuel injection pump (4) that forms part of a system (1) for injecting fuel into a motor vehicle internal combustion engine (12), the pump (4) comprising at least one piston (19) moving in a chamber of the pump (4) between a top dead center (25) for which the volume of the chamber is at its smallest and a bottom dead center for which the volume of the chamber is at its greatest, the pump (4) being equipped with a digital control valve (13) for controlling the quantity of fuel fuel delivery, this valve being commanded electrically between an open position in which a high-pressure part of the injection system is not supplied with fuel and a closed position in which the high-pressure part of the injection system is supplied with the digital valve (13) then being in a fully closed position, an electrical current being applied to the digital valve (13) as it closes then removed in order to open the digital valve (13), a movement of the digital valve (13) toward its open position creating an induced current which, when its profile over time is monitored, makes it possible to detect a position of start-of-opening (23) of the digital valve (13) and the instant at which this occurs, wherein an angular position at an instant at which the pump (4) piston (19) passes through pump (4) top dead center (25) is estimated as a function of an angular position of the instant at which the position of start-of-opening (23) of the digital valve (13) appears, the estimate of the angular position at the instant of passing through top dead center (25) as a function of the angular position at the instant at which the position of start-of-opening (23) of the digital valve (13) appears taking account of at least one of the following parameters:

• the pressures upstream and downstream of the pump (4), the elastic modulus of the fuel, which is dependent on its temperature and pressure, technical characteristics of the pump (4) such as its dead volume and its swept volume.