Duty cycle measurement for electromagnetic valve drive - has threshold switch, integrating capacitor and current source temp. compensation

摘要

A duty cycle measurement device for an input signal subject to noise is used to control the electromagnetic valve in a fuel delivery system of an IC engine is simply constructed, operates accurately and reliably, and is insensitive to noise. It also operates independently of the type of current regulation used for the magnetic valve. The output of a threshold switch (25) with a switchable threshold level is connected directly or indirectly to a controlled current source (27) driving an indicator (48). A capacitor (42) integrating element may be connected to the current source (27) input. The current source has a temp. compensation zener diode (41) also connected to its input. For an electromagnetic valve operating voltage of approx. 14 volts the threshold levels are approx. 7 and 25 volts.