Fuel Injection Counting
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Posts: 46,084
FYI
The use of fuel measurement transducers is typically
used on Dynos where the engine speed and load is
controlled. Even in these controlled environments what
you are describing is very difficult to obtain
accuracy. Thus what is typically done is to measure
consumption only, by feeding the return line back into
the inlet of the pressure pump. Into this loop fuel is
feed at 5 psi through a "consumption only transducer".
Fuel measurement of A-B fuel channels is full of
problems related to accuracy.
For all other vehicle operations, the pulse width of
the injector times the frequency results in a
reasonably good piece of data for observational
purposes. Still not as good as consumption only
measurements for accuracy.
One problem is that most transducers to not have a
constant pulse per gallon over a variable gallons per
minute when graphed. Thus for accuracy the
characteristics of the flow meter have to be
incorporated into a lookup table to linearize the data
and obtain the accuracy desired.
I do this type of thing for a living and one can spend
thousands of dollars to do it right (meaning accurate)!
Thus there is nothing simple about it, the job requires
attention to details typically not thought of. If you
do not have the capability to characterize the
transducers for output counts/gal vs. flow rate
gallons/hr. for accuracy then the result will be
suspect.
Sincerely,
Ron A.
DDS, Inc.
ronaldsa@e...
Message: 1
Date: Thu, 10 Jun 2004 18:26:27 -0000
From: "daytonacopue" <turbo_tex@h...>
Subject: Re: Stamp counting capabilities
I want to build a simple fuel differentiator. On a
Electronic Fuel
Injection sytem. The fuel system has a send and return
line. A
transducer has to be placed into each line. The
transducers will
pulse 3300/liter or 7000 depending on application. The
fuel pump will
pump 110 to 140 liters per hr depending on pump. For
3300
pulses/Liter usage 140 Liter/hr = 2.33 Liter/min = 7689
pulses/min =
128 pulses/sec. For 7000 pulses/Liter usage 140
Liter/hr = 2.33
Liter/min = 16310 pulses/min = 271 pulses/sec.
The two transducer pulse counts will be subtracted to
determine the
pulse count of fuel used. I am reading about the Stamps
and do not
know their capabilities. I thought I might have to
build counters but
wanted to make sure.... I could use the counter to
interupt the Stamp
to read, subtract, clear the counters, and display to
update. I also
thought about sampling the pulses for frequency and
calculate but it
would not be as accurate. I need accuracy...
The use of fuel measurement transducers is typically
used on Dynos where the engine speed and load is
controlled. Even in these controlled environments what
you are describing is very difficult to obtain
accuracy. Thus what is typically done is to measure
consumption only, by feeding the return line back into
the inlet of the pressure pump. Into this loop fuel is
feed at 5 psi through a "consumption only transducer".
Fuel measurement of A-B fuel channels is full of
problems related to accuracy.
For all other vehicle operations, the pulse width of
the injector times the frequency results in a
reasonably good piece of data for observational
purposes. Still not as good as consumption only
measurements for accuracy.
One problem is that most transducers to not have a
constant pulse per gallon over a variable gallons per
minute when graphed. Thus for accuracy the
characteristics of the flow meter have to be
incorporated into a lookup table to linearize the data
and obtain the accuracy desired.
I do this type of thing for a living and one can spend
thousands of dollars to do it right (meaning accurate)!
Thus there is nothing simple about it, the job requires
attention to details typically not thought of. If you
do not have the capability to characterize the
transducers for output counts/gal vs. flow rate
gallons/hr. for accuracy then the result will be
suspect.
Sincerely,
Ron A.
DDS, Inc.
ronaldsa@e...
Message: 1
Date: Thu, 10 Jun 2004 18:26:27 -0000
From: "daytonacopue" <turbo_tex@h...>
Subject: Re: Stamp counting capabilities
I want to build a simple fuel differentiator. On a
Electronic Fuel
Injection sytem. The fuel system has a send and return
line. A
transducer has to be placed into each line. The
transducers will
pulse 3300/liter or 7000 depending on application. The
fuel pump will
pump 110 to 140 liters per hr depending on pump. For
3300
pulses/Liter usage 140 Liter/hr = 2.33 Liter/min = 7689
pulses/min =
128 pulses/sec. For 7000 pulses/Liter usage 140
Liter/hr = 2.33
Liter/min = 16310 pulses/min = 271 pulses/sec.
The two transducer pulse counts will be subtracted to
determine the
pulse count of fuel used. I am reading about the Stamps
and do not
know their capabilities. I thought I might have to
build counters but
wanted to make sure.... I could use the counter to
interupt the Stamp
to read, subtract, clear the counters, and display to
update. I also
thought about sampling the pulses for frequency and
calculate but it
would not be as accurate. I need accuracy...
Comments
Consumption only is what I need to measure. If I could get 5%
accuracy, I would be happy. One sensor states .025% repeatability /
Linear to 1% on frequency output versus flow (graphed) / upto 3%
error between sensors.
You stated "One problem is that most transducers to not have a
constant pulse per gallon over a variable gallons per
minute when graphed."
Are you saying that the tranduscer manufactures 1% linearity graphing
is incorrect. Example: With 1% linearity, .5 liters/min is 60 pulses,
1.5 liters/min 180 pulses.
Maybe my statement of accuracy is a little off.
In endurance racing the class we run is limited to a max of 10
gallons fuel per pit stop. In a 25hr race, being able to pit with a
5% error margin would be excellent. This .5 gallon is what I would
consider accurate. In racing, fuel guages do not read well with the
fuel against the side of the tank.
With the electric fuel pump and a return line, the fuel flow in gals
per sec / minute / hr etc will be constant for the send transducer.
The return transducer will only see a flow reduction of .005 gal per
second max at full throttle.
A calibration can be performed between the two sensors for freq
offset each time the fuel pump has power before starting. This should
narrow the upto 3% error between sensors.
--- In basicstamps@yahoogroups.com, "Ronald Anderson" <ronaldsa@e...>
wrote:
> FYI
>
> The use of fuel measurement transducers is typically
> used on Dynos where the engine speed and load is
> controlled. Even in these controlled environments what
> you are describing is very difficult to obtain
> accuracy. Thus what is typically done is to measure
> consumption only, by feeding the return line back into
> the inlet of the pressure pump. Into this loop fuel is
> feed at 5 psi through a "consumption only transducer".
> Fuel measurement of A-B fuel channels is full of
> problems related to accuracy.
>
> For all other vehicle operations, the pulse width of
> the injector times the frequency results in a
> reasonably good piece of data for observational
> purposes. Still not as good as consumption only
> measurements for accuracy.
>
> One problem is that most transducers to not have a
> constant pulse per gallon over a variable gallons per
> minute when graphed. Thus for accuracy the
> characteristics of the flow meter have to be
> incorporated into a lookup table to linearize the data
> and obtain the accuracy desired.
>
> I do this type of thing for a living and one can spend
> thousands of dollars to do it right (meaning accurate)!
> Thus there is nothing simple about it, the job requires
> attention to details typically not thought of. If you
> do not have the capability to characterize the
> transducers for output counts/gal vs. flow rate
> gallons/hr. for accuracy then the result will be
> suspect.
>
> Sincerely,
> Ron A.
> DDS, Inc.
> ronaldsa@e...
>
>
>
> Message: 1
> Date: Thu, 10 Jun 2004 18:26:27 -0000
> From: "daytonacopue" <turbo_tex@h...>
> Subject: Re: Stamp counting capabilities
>
> I want to build a simple fuel differentiator. On a
> Electronic Fuel
> Injection sytem. The fuel system has a send and return
> line. A
> transducer has to be placed into each line. The
> transducers will
> pulse 3300/liter or 7000 depending on application. The
> fuel pump will
> pump 110 to 140 liters per hr depending on pump. For
> 3300
> pulses/Liter usage 140 Liter/hr = 2.33 Liter/min = 7689
> pulses/min =
> 128 pulses/sec. For 7000 pulses/Liter usage 140
> Liter/hr = 2.33
> Liter/min = 16310 pulses/min = 271 pulses/sec.
>
> The two transducer pulse counts will be subtracted to
> determine the
> pulse count of fuel used. I am reading about the Stamps
> and do not
> know their capabilities. I thought I might have to
> build counters but
> wanted to make sure.... I could use the counter to
> interupt the Stamp
> to read, subtract, clear the counters, and display to
> update. I also
> thought about sampling the pulses for frequency and
> calculate but it
> would not be as accurate. I need accuracy...