MembersPage/GergelyLezsak/InjectorMeasurement (2007-01-26 01:34:00)

Injector measurement

I was interested in injector opening/closing time regarding to flyback setups.

All of the below measurements made on a 12 Ohm Hi-Z injector dry -without fuel pressure-, and PowerFlyback installed inside the ECU. No PWM-ing was enabled, pulse width is ~14ms.

NEWS 2007.01.22

I've put together a flowbench-setup

flowpad-small.jpg

First tests showed that injector opening time increased slightly according to the fuel pressure introduced (3 bars). No flow measurement data yet.

Question: How can I force GenBoard to a specific pulsewidth?

-Tried "mxofemxofemxp05mxp05" and similar, but no effect at all.

I would use a soundcard ElectronicDesign/TriggerSignalGenerator with 60-2 or similar pattern, and use "cranking RPM" (both low-temp and high-temp values set to same pulsewidth). you can bump up cranking_thresh, but best to apply 290 RPM or similar. Take care (and have multiple fire extinguishers at hand).

  • You might want to measure (if measuring 'acutal' flow rate) at around 6000 1/min (ie. 100 Hz) or similar (depending your engine maximum revolutions etc.) and around 80-85 % opening time (ie. 8,0-8,5 ms at 100 Hz). //BengtR

Voltage was 12.1-12.2V, voltage/current measurements were made after a 0.3Ohms resistance, so test setup is like:

+12.2V____[0.3Ohms]____*Measurement*____[injector]____INJ-OUT

The results:

3flyback.gif

Red channel means measurement voltage (or current).

Blue channel means mechanical movement/noise.

-all of them includes internal PowerFlyback-

It's visible on the red channel that after opening (about 1ms later) current has a pulsation which shows the movement of injector iron core. At the same time mechanical noise started (blue channel).

At closing phase there's not visible current-pulse in red channel but a spike goes well over starting (+12V) voltage which is the inductive "kick-back" or flyback current. Blue channel's mechanical noise shows here the exact position of mechanical injector closing.

As my movement/noise detection (knock sensor) was nearly installed on the injector it's coil slightly picked up injector current, so on the blue channel it's also visible when injector current switched on/off (a single spike before noise).

inj_knock3.jpg