Air flow devices
Air flow devices
(OP)
An auto manufacture calls the induction air metering device an AIR FLOW METER, it works on the Carmen vortex principle.
An other manufacture calls the induction air metering device a MASS AIR FLOW SENSOR, it works on the hot wire principle.
Other than how they function what do they measure that is different? Is it just a nomenclature deal?
If air density is the same and calibration is the same won't they both see the same flow?
An other manufacture calls the induction air metering device a MASS AIR FLOW SENSOR, it works on the hot wire principle.
Other than how they function what do they measure that is different? Is it just a nomenclature deal?
If air density is the same and calibration is the same won't they both see the same flow?





RE: Air flow devices
"Schiefgehen wird, was schiefgehen kann" - das Murphygesetz
RE: Air flow devices
it can throw codesit can detect sensor failure etc.Cheers
Greg Locock
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RE: Air flow devices
Hemi - although almost all sensors of any property only "infer" the value of that property, there are many MAF sensors that respond in a direct relationship to mass air flow. Hot wire MAF sensors (plus other heat transfer types) and Coriolis mass flow sensors to name a couple.
je suis charlie
RE: Air flow devices
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?
RE: Air flow devices
"Schiefgehen wird, was schiefgehen kann" - das Murphygesetz
RE: Air flow devices
Also did some checking on hot wire devices and they do require compensation for temperature due to the viscosity and thermal conductivity dependence of air. They do not require compensation for density changes due to altitude (pressure).
Hemi, the response of HW AMM (filament current) to mass flow is extremely precise but nonlinear (approx square root).
je suis charlie
RE: Air flow devices
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?
RE: Air flow devices
je suis charlie
RE: Air flow devices
Splitting hairs. Engineers don't normally get into that stuff.
In this discrete universe, counting is the only true measure you really have. Mass flow is possible, given good vision, enough fingers and some absolute definition of time (that's not defined in relation to something else).
Steve
RE: Air flow devices
RE: Air flow devices
The vortex sensor is measuring the frequency of vortex oscillations, which are proportional to mass flow, while the hot wire sensor is measuring the forced convection property of the air flow. Fundamentally, they are using different properties of air to infer what the mass flow was.
TTFN
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RE: Air flow devices
Measuring mass flow rate of an airstream without causing too much back pressure, reliably and cheaply, would appear to be trickier than a first glance indicates.
Bear in mind that in addition to the sensor check I mentioned, the O2 sensor and fuel injector pulse width also provides another check on the MAF. A significant effort is expended in the last 2 years before job 1 in replacing actual measured properties by ones that can be inferred from the multiple methods of measuring the engine.
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?
RE: Air flow devices
"Schiefgehen wird, was schiefgehen kann" - das Murphygesetz