Are there in-tank ethanol/gasoline ratio sensors? 1

[DasKleineWunder]

Are there some sensors submerged that can measure the approximate ethanol to gasoline ratio in the fuel tank?

So far I've only heard of exhaust sensors.
Is there a more direct way to measure this ratio?
Maybe some sensors still in R&D stage?

 

[dgallup]

There are inline sensors used to measure the ethanol content in the fuel rail. I have heard their use is diminishing because they are expensive and unreliable. The auto makers seem to be able to get away with just using the lamda sensors which they have to have anyway.

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[GregLocock]

A big part of engine development is to get rid of as many sensors as possible. With a new installation you typically start with a few extra sensors, then as you establish cross correlation and build models in the ECU you can get rid of the direct measurements of some of the parameters. Having said that, I've never seen an upstream device to measure ethanol %, it it has been handled by knock and exhaust gas analysis.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

http://eng-tips.com/market.cfm?

 

[Comcokid]

I actually designed a sensor some years back that would do this. It was a no-moving-part fuel-level sensor that with a few extra line of code in the processor (a small microcontroller) could also measure ethanol or detect water. Adding the feature didn't require any additional parts. Got a patent (which was assigned to the employer). However that employer never did any additional development. Got a lot of complements from others who worked with the measurement technology used. Promised "$1 plus other considerations" from the employer, but never even saw the $1. At least I got a line in my resume.

 

[Compositepro]

A measurement of dielectric constant of the fuel should be pretty sensitive to the ethanol/gasoline ratio. The sensor would simply be two electrical probes in the fuel. The electronics would be a little more complicated.

 

[WGJ]

I'm pretty sure that the old AC Rochester company had a dielectric sensor back in the 80's

Bill

 

[pmrobert]

They exist, have for a while and they are expensive. See

http://www.ebay.com/bhp/flex-fuel-sensor

for numerous examples. That said, I've had a device from Ford successfully providing input to an aftermarket ECU for 9+ years for a turbo Wankel engine for a while. It has worked for ethanol/gasoline ratios from 85/15 to 0/100 with no drama.

 

[Comcokid]

Standard dielectric constant sensors (aka capacitance sensors) suffer from severe inaccuracies to totally bogus readings with some additives to fuels. Like MBTE added to oxygenate fuel, and additives to remove moisture from fuel tanks.

 

[Compositepro]

Well if you want a sensor specific to ethanol and nothing else, that would be a gas chromatograph. The gas drier is isopropyl alcohol and it maybe a good thing to sense it as ethanol rather than gasoline.

 

[DasKleineWunder]

There are inline sensors used to measure the ethanol content in the fuel rail. I have heard their use is diminishing because they are expensive and unreliable. The auto makers seem to be able to get away with just using the lamda sensors which they have to have anyway.

Thanks for your replies guys.
What do you mean by unreliable?
Is it that they are inaccurate or that they break down?

I actually designed a sensor some years back that would do this. It was a no-moving-part fuel-level sensor that with a few extra line of code in the processor (a small microcontroller) could also measure ethanol or detect water. Adding the feature didn't require any additional parts. Got a patent (which was assigned to the employer). However that employer never did any additional development. Got a lot of complements from others who worked with the measurement technology used. Promised "$1 plus other considerations" from the employer, but never even saw the $1. At least I got a line in my resume.

Would you mind disclosing more details on this patent? Maybe the patent number?
I assume you measured electric conductance didn't you?
I seem to recall that ethanol conducts electricity slightly better than alkanes. Did fuel additives fool the sensor?

Well if you want a sensor specific to ethanol and nothing else, that would be a gas chromatograph. The gas drier is isopropyl alcohol and it maybe a good thing to sense it as ethanol rather than gasoline.

Accurate but isn't it too large and heavy for a car?
Maybe some ionizer and detector might help?
Maybe small amounts of a slightly radioactive element (like those in smoke detectors, coupled with a simple detector?

 

[dgallup]

Just google flex fuel sensor or go buy one off ebay or your local car parts store.

http://www.haltech.com/flex-fuel-sensor-explained/

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[Comcokid]

DasKleineWunder - The fluid level measurement technology I worked with was based on time-domain-reflectometer (TDR) technologies where the fuel probe was transmission line (rf transmission line) in the fuel. In this system the reflection from the air/fuel interface is measured to determine the fuel level. However another reflection from the end-of-probe is received, and the time of this reflection is affected by the fuel level, and the velocity-of-propagation of the pulse in the fuel, which is directly related to the rf dielectric constant of the fuel. US Pat. 5,898,308 issued April 1999. The pulse and sampling circuits used could either be of the public domain type, or the lower cost and simpler versions available under license and known as "Micropower Impulse Radar" or "Guided Wave Radar". It may be that some of these MIR and GWR circuit patents are either expired or close to expiration.

 

[HokieFan]

Continental makes in-line ethanol sensors...

http://www.conti-online.com/

http://www/automotive_de_en/themes/passenger_cars/powertrain/sensors_actuators_en.html?page=2