Injection timing transducer

Abstract

An injection timing transducer is provided for use with the fuel delivery system of a compression ignition engine. The transducer is operatively associated with the fuel flow path and provides a signal indicative of fuel pressure pulsations within the fuel delivery system. The electrical signals are representative of the derivative or rate of change of fuel pressure as a function of time and are thereby particularly suited for indicating the onset of fuel injection to the engine. The transducer includes a housing member connectable in the fuel flow path intermediate a fuel pump and injector for defining a chamber through which the fuel may pass and for providing a sensor mounting surface external to the chamber but in pressure transmitting relationship with the fluid path. A piezoelectric sensing element is affixed to the sensor mount surface of the transducer housing member. The housing member is typically an elongated, generally tubular member having a central fuel flow path at either end and wherein the chamber is an annular region within the member and radially offset from the central flow path. A continuous flow of fuel through the chamber is provided by radial flow paths between the central flow path and the upstream and downstream ends of that chamber. The annular chamber is conveniently provided by an insert member inserted in radially spaced relation within a central bore in one end of the housing member.