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In response to
the October 1, 2002 EPA emissions
standards, Kavlico has developed a
two-fold sensor approach to reducing
the formation of NOx emissions for
on-highway vehicle applications.
Fluid level measurements
are important for OEM engine manufacturer’s
that are targeting urea/water based
(SCR) selective catalytic reduction
systems. Injecting urea into the exhaust
stream directly reduces the formation
of NOx. To support this approach to
emissions control, Kavlico has developed
two sensors for urea level monitoring
and measuring.
A combination of
Kavlico sensors can be used to measure
urea fluid level and infer changes
in composition of the fluid that could
be caused by system tampering. One
sensor can be used to measure the
dielectric constant of the fluid which
changes in proportion to urea concentration.
Another dielectric sensor can be arranged
vertically so that its output changes
with fluid level and dielectric constant.
A third sensor can be used to measure
pressure at the bottom of the tank
indicating a combination of fluid
and density level. Taken together
or in pairs, these sensors can indicate
both fluid level and urea concentrations.
The second approach
actually measures the pressure of
the fluid and provides a proportional
voltage output to fluid level.
Both sensors operate
on 5 Vdc power supply, have robust
design elements such as all stainless
steel wetted parts, and can be customized
to the application-specific need of
the particular OEM requirement.
When used in combination,
the two sensors can measure both level
and the concentration of urea in the
fluid. The benefit of this is that
logical statements can be made about
the concentration of the fluid enabling
the control system architect’s
to alert owners of unwanted tampering,
incorrect fluids, and inappropriate
mixture ratios.
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