Fuel injection device and adjustment method thereof

摘要

A fuel injection device (fuel supply system) of a common rail type fuel injection system for an engine includes a pressure sensor disposed in a fuel inlet of an injector for measuring a fuel pressure at a position where the sensor is disposed and an ECU for sensing various kinds of pressure fluctuations associated with the injection including a pressure leak due to an injection operation of the injector and waving characteristics due to actual injection thereof based on sensor outputs from the pressure sensor. The ECU serially obtains the sensor outputs from the pressure sensor at intervals of 20 μsec.

主权项

1. A fuel injection device of a common rail type fuel injection system for an engine, the fuel injection device comprising:
at least one fuel passage pressure sensor disposed in a fuel passage between a point of a pipe connected to a fuel discharge port of a common rail apart from the common rail by a certain distance and a fuel injection hole of an injector connected to the pipe, the sensor measuring a fuel pressure at a position where the sensor is disposed; a pressure fluctuation sensing device configured to sense a pressure fluctuation caused by at least one of an injection operation of the injector and actual injection actually performed through the injection operation based on a sensor output from the fuel passage pressure sensor; and an injection characteristic detecting device configured to detect at least one injection characteristic of the injector based on the pressure fluctuation sensed by the pressure fluctuation sensing device, wherein the injection characteristic detected by the injection characteristic detecting device is at least one of an actual injection rate and a fluctuation of the actual injection rate in an injection period of the injector, wherein the actual injection rate is an instantaneous injection quantity of fuel in a time interval shorter than the injection period; wherein the pressure fluctuation sensing device is configured to obtain multiple pressure sensor values, which are respectively sensed at multiple timings including a timing near an injection timing during the injection, from the at least one fuel passage pressure sensor at time intervals which are shorter than the injection period; and wherein the injection characteristic detecting device is configured to: calculate a difference value between each of the multiple pressure sensor values and a pressure value, which is caused by a pressure decrease from a common rail pressure in the common rail due to fuel leak after start of an injection start command, to obtain a series of difference values including the difference value; and detect the actual injection rate based on the series of difference values.