PRESSURE SENSOR DIAGNOSING METHOD, AND COMMON RAIL TYPE FUEL INJECTION CONTROL DEVICE

摘要

Disclosed is a pressure sensor diagnosing method for making it possible to diagnose the presence/absence of abnormality with a simple constitution but without providing any dedicated circuit for diagnosing the action of a pressure sensor.  An electronic control unit (4) feeds fuel injection valves (2-1 to 2-n) acting as a piezo-injector with a predetermined drive current (Is) for a predetermined drive time (ET).  In the ringing of the terminal voltage of the piezo-injector which occurs for the feeding period, the potential difference between a first peak voltage which occurs at first after the power feed and a second peak voltage which occurs next is determined.  A standard rail pressure intrinsic to the potential difference is determined on the basis of a predetermined correlation between the potential difference of the first peak voltage and the second peak voltage and the standard rail pressure.  It is determined that the pressure sensor (11) is abnormal, if the difference from a detected rail pressure obtained by a pressure sensor (11) is larger than a predetermined threshold valve.