Flow sensors and meters

[nitor]

Hi, I'm not quite sure if this is the right place to ask project questions, but here goes.. =)

 

In the future, I would like to make a fuel sensor/metering system for my car that would monitor the flow along the fuel line and give me a reading in real-time of how many mL of fluid are being consumed. I've decided to put off setting myself and my property ablaze for the time being, and would like to attempt this on a simple fountain first.

 

I've searched the web, and haven't found any small digital flow sensors that can be attached to a tube and output the data in any usable manner. Where can I look? Does anyone have any experience with this sort of thing?

 

Any help would be much appreciated.

[insane_alien]

these things already exist and have been used in several makes of car. (all if you include the testing of the engines during the design phase.)

 

venturi meters are particularly good at his as the have no moving parts and it is a simple translation from pressure to temperature.

 

pitot tubes could also be used but would impede flow slightly more.

[Flashman]

If you have a car that uses electronic fuel injection, it's easier to derive it from injector pulse data.

[nitor]

I looked into venturi meters, and they seem like a viable possibility-- but where do I get a nice little digital one?

 

insane_alien: My car does have electronic fuel injection, but it is from 1987-- ODBI was not very standardized and I don't have any clue on how to get that sort of data from the system (if it was even put over the same bus).

[ydoaPs]

I thought venturi meters weren't all that accurate at low flow rates. I'd have to run the math, but I think for the fuel system on an average automobile, you'd either restrict flow too much or you'd need a ridiculously sensitive and accurate DP cell.

[Flashman]

You can cheat and just read pulses off the injector harness.

[ydoaPs]

You can cheat and just read pulses off the injector harness.

 

If it's positive displacement

[Flashman]

It should be within a percent or two if you just take the known delay of the injector and the known flow rate at known regulated pressure.

 

For example, your injectors are specced at 14lb/hr@45psi, your fuel pressure regulator is 45psi, you see 25% duty cycle on them at 60mph, 4 cylinders, you're using 14lb an hour total, with a fuel that weights 7lb a gallon that's 30 miles to the gallon.

[nitor]

Well I'm really looking to get a real-time rate of combustion in mL, is there some sort of pulse sensor or some other non-invasive sensor other than optical (too expensive)?

[nitor]

..So no one can point me in the right direction?

[iNow]

Google told me to look here:

 

http://www.ingramproducts.com/flowmeter.html?vcn=google&vcad=Other_Flow-PressureMeters&_vsrefdom=Other_Flow-PressureMeters&gclid=COyVxPCQ-ZYCFRKAxgodg1HV_Q

 

http://www.ara.bme.hu/english/oktatas/labor/M8.doc

 

http://www.isa.org/InTechTemplate.cfm?Section=Control_Fundamentals1&template=/ContentManagement/ContentDisplay.cfm&ContentID=44735