Analysis of volume in a fuel tank

Most fuel tanks have baffles fitted to attempt to stop the fuel sloshing around to much.

A level gauge could give a reasonably accurate output. If you want a higher accuracy why not average the resulting output to stop the sloshing about from causing errors?

A centuries old technique to measure the water level in the harbour without interference from waves: a pipe connection to another reservoir (you have to determine the diameter!). The pipe will integrate the movement, in the second reservoir having the right level. Notice that the tides are very well sensed.

I noticed that I replied to answer #1. Sorry, it was intended for the main poster.

do you intend to say, by providing a smaller dimension measuring area will minimize fluctuation?? something like a small tube which will seek the level of the original fuel level and still eliminate fluctuations

No, I am saying that a small diameter pipe to another reservoir will integrate the fluctuations due to movement or vibration. Of coarse, the reservoir has to be shaped such that it will not be affected (too much) by the same.

on no indel.. you.ve got me all wrong... in measuring the depth of the reservoirs in case of river dams, they build a well with a opening underneath so that the well is isolated from the surface and still seeks the same level as the water level.. this eliminates the waves due to wind.. and the level can be more accurate.. i was planning to put a capillary in the tank and measure the liquid level in the capillary.. but i found few problem in that.. thats why looking for other methods.. any suggestions??

Bst way would be just to stop the vehical and observe, if you need real accurate level. Otherwise, practically, what is displayed is good enough.

Besides, remember that that is dispayed is not the volume, but the level. I do not think that the fuel tank is uniform in shape heightwise, to show the volume.

to stop the vehilcle and observe is the best way i've devised till now.. later using flowmeters in the fuel outline i can deduct the amount of fuel gone out and estimate the volume inside... i wish to know if there are any better ways to the problem..

Note that some vehicles see this as a natural occurrence. You may need to execute the options detailed in the earlier posts.

Some vehicles use a voltage regulator to control the fluctuations with the needle. If your vehicle has this setup, you could have some malfunction.

And, some use software with the onboard computer to control the fluctuation. Again, if you have this setup, possible problems.

If the reading is reasonably stable, the previous suggestions are quite acceptable.

good idea guys.. i'm planning to fabricate an instrument to determine the distance the vehicle can travel with the remaining fuel and planning to implement it in 2 wheelers.. so all these methods are not accurate enough..

Of course, you probably realize there is a certain circuitous logic to this approach. Even if your fuel-remaining measurement is accurate to three significant digits, your prediction cannot be accurate, because you cannot know in advance the terrain, travel speed, idle times, etc. So the remaining distance to be traveled can only be an estimate based on past averages.

You could construct a fuel flow measuring device that would determine fuel remaining, based on fuel used from a full tank, but you'd still have the issue of predicting the unpredictable.

A GPS unit could "learn" the fuel consumption characteristics of the vehicle (based on speeds, gradients, etc.) and could then predict the fuel to be used over a planned trip, based upon the terrain data and speed limit data for the projected trip. But even then, traffic conditions can change unpredictably.

Perhaps just a well-designed fuel gauge, with its pickup near the center of the tank to minimize angle and sloshing effects (and interfaced to a tiny microprocessor to calibrate it for tank shape and non-linearities in the pickup) would be sufficient, given that the accuracy with which you can measure the fuel level with such a device would exceed the accuracy with which you can predict future consumption.

If you believe you can accurately predict how far the vehicle will travel on a given amount of fuel, then just reset an odometer at fill up.

the old, measure it with a micrometer, mark it with a piece of caulk, then cut it with a axe.

I like to remind people that a single fuel meter doesn't work on modern fuel injected cars, it takes a second one to measure the return fuel.

no buddy.. i think I've got a better solution to the problem.. i believe that the distance traveled to the fuel consumed is the total efficiency in any case.. it goes like this.. i have a flow meter in the fuel line which is going to send an actuation signal for every specific quantity of fuel (say 100ml). the signal is sent to the PLC where it has already been recording the odometer from the point the start signal has been sent by the flow meter.. when the flow meter finishes the 100 ml limit the odometer reading is noted (say 5 kms) then the electronic circuits can multiply the remaining quantity (say 5 lits) then the distance that can be travelled with the remaining (5 lits) fuel is (250 kms) thats how i've planned it.. any change in the conditions is gonna directly affect the system and all will be covered..

it goes like this.. i have a flow meter in the fuel line...

You've describe the logic of a standard fuel or "trip" computer that can be found on many automobiles. (In automobiles, these can operate without any additional fuel flow measuring devices in the supply and return lines, because the actual injected amount can be obtained from the ECU.)

Just as the "Time to Destination" display on a GPS unit is often completely incorrect, so to is the "Miles to Empty" on a trip computer display. The fuel computer has no way of knowing that between you and your destination is a run up a mountain (in which case your fuel consumption per mile will increase by a factor of 5 or more) or an run down into a valley, (in which case your consumption will drop by a factor of 5 or more). Likewise, it cannot know that you are about to sit in a traffic jam for an hour, consuming fuel, but producing no forward movement.

Of course the basic idea of measuring fuel remaining in the tank by measuring and totalizing fuel flow out of the tank is a valid one. Such systems can tell you the actual amount of usable fuel in the tank to fairly precise limits, once calibrated, and have been in use, especially on aircraft, for many decades. If you can produce such a system at very low cost, perhaps you could find a market in the two-wheeled world. I'd have to admit however, that in some million miles of driving two and four-wheeled vehicles, I have never had a strong desire for such a unit -- it is just too easy to keep track of the amount of fuel in the tank, and to ere on the side of filling up ealier, rather than later. But many people pay extra for trip computers in cars, so there is no doubt a market for them in two-wheeled vehicles too.

i believe that the distance traveled to the fuel consumed is the total efficiency in any case

This is not the case. Engine efficiency varies dramitically with load, and overall vehicle fuel efficiency varies dramatically with speed, grade, etc.

We manufacture boats which have very inaccuarate fuel tank gauges due to the various angle and wave effects.see www.explorermarine.co.uk .

Our outboard suppliers provide electronic fuel flow meters which predict fuel remaining from the fuel inserted and the fuel used. Very accurate, but a bit of a bother.

My VW car uses the same technology to measure fuel consumption, but also has an electronically damped fuel gauge to know how much is still in the tank

hey thats great.. any idea how its achieved and is it possible to put it on a 2 wheeler??? and also give me the details of your boat method if possible.. thanks man.. if you have to e mail the details here is my ID : srihari.cit@gmail.com

All the best for the price of the project

thats valid.. very valid.. may be if i get something done i can work it out cheaper in mass production but at the rate our ideas flare the apparatus will go more costly that the 2 wheeler itself..

Our engines are BRP Evinrude outboards and the fuel flow metering is connected to the Rev counter which has the microprocesser in it and two simple menu buttons on the front next to a two line text display. I believe that Faria make the instrument for BRP.

Good luck

thanks man.. any other personal ideas to achive this in a smaller scale tank?????

If the transmitter is electrical, then an electrolytic capacitor across the output will help average out the fluctuations.Larger will give more even reading, but will be less responsive to sudden level changes.Smaller will be more responsive, but less stable.Experiment with various sizes to determine best value for your application.

Start with,say 500 mfd., and work up or down in value for best results.Paralleling capacitors increase value,series decreases value.

Simplest way I know for simple voltage-output(potentiometer, or rheostat) sender unit.

HTRN

Fuel gages in automotive fuel tanks are usually very heavily damped (filtered). This keeps the level indication from changing with every slosh of the tank. Depending upon the type of measurement and indication devices used, applying a good healthy dose of damping say on the order of fifteen to sixty seconds or more for a full scale change should give you a short term average level indication, which is what you want.

Another consideration is where you choose to put the sensing element in the tank. The best place is usually close to the geographical center of the tank. If you sense the tank level in the center, it will show less apparent change as the fuel sloshes from front to back and side to side so you will have less noise to filter out.

I have also seen fuel tanks with mechanical level indicators which used a variation of the tide level gauge principle discussed above. It was done by enclosing the float inside a vertical tube a little larger than the float. The tube was welded to the inside bottom of the tank and had a small hole about 3 to 5mm in diameter in its side right at the bottom of the tank. With this system, the filtering was provided by the volume of the stand pipe/tube and the size of the hole at the bottom.

Have a joyous life!

TT3

If your motorcycle is fuel injection equipped you should be able to measure the fuel consumption by monitoring injector open time instead of using an expensive electronic flow meter.

With an EFI vehicle, you should be able to do it for less than 20$. Have a look at the ecomodder's MPGuino which seems to be exactly what you want to do and is working quite well.

Lova Andriamanjay