Note: Descriptions are shown in the official language in which they were submitted.
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TITLE: FUEL COMPOSITION SENSING SYSTEMS AND METHODS
USING EMF WAVE PROPAGATION
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional Application No.
60/875,439, also entitled Fuel Composition Sensing Systems and Methods Using
EMF
Wave Propagation, filed December 18, 2006, which is also incorporated herein
by
reference. This application is also related to U.S. Patent Application Serial
No.
11/431,912, filed May 10, 2006, entitled System and Method for Sensing Liquid
Levels
Using EMF Wave Propagation, and U.S. Patent Application Serial No. 11/800,965,
filed
May 8, 2007, entitled Liquid Level and Composition Sensing Systems and Methods
Using EMF Wave Propagation, both of which are additionally incorporated herein
by
reference.
BACKGROUND OF THE INVENTION
Field of the Invention
[0002] This invention relates generally to systems and methods for sensing
types of
liquids passing through a line or stored in fuel tanks and other containers.
More
particularly, the present invention relates to sensing the constituents of
fuel in a Flexible
Fuel Vehicle by propagating electromagnetic waves into a liquid container or
fuel line.
Particular embodiments of the present invention detect fuel composition and
alcohol
content in a fuel line of a Flex Fuel Vehicle.
Description of the Prior Art
[0003] Flex Fuel Vehicles (FFVs) are motor vehicles which are compatible with
the
use of alcohol as a significant constituent of the vehicle's fuel. Alcohol
based fuels are an
alternative type of renewable, transportation fuel made from bio-material,
potentially
reducing dependence on petroleum based fuels. A motorist may advantageously
gain
increased horsepower for better engine performance because alcohol based fuels
typically
have a higher octane rating than premium gasoline. Alcohol based fuels include
"E85," a
term for motor fuel blends of 85 percent ethanol and 15 percent gasoline. E85
is an
alternative fuel as defined by the U.S. Department of Energy and is intended
for use in
FFVs. Ethanol and other alcohols burn cleaner than gasoline and is a
renewable,
domestic, environmentally friendly fuel. FFVs can typically be fueled on any
blend of
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ethanol and gasoline, from 0% ethanol and 100% gasoline up to 85% ethanol and
15%
gasoline (E85).
[0004] It is important for the Engine Management System (EMS) of an FFV to
have information on the composition of the fuel, so that the EMS may adjust
certain
vehicle parameters to optimize vehicle performance, specifically fuel
consumption,
emissions control and engine power.
[0005] Motor vehicle operators generally rely on indirect methods of
determining
the amount of alcohol in an FFV's fuel tank. The most common method of
establishing
the alcohol content of the fuel remaining in a motor vehicle is to use
software algorithms
implemented in the Body Controller Module or EMS of the vehicle. Alcohol
content of
the fuel may be altered by the driver at each filling of the fuel tank as
there is no
requirement to continuously use E85 fuel or conventional gasoline. Algorithm-
based
systems are slow to react to changes in the fuel composition and are typically
only
accurate to plus or minus ten percent alcohol content. Furthermore, such
systems are
even more ineffective when employed in a motor vehicle with saddle fuel tanks
or
similar fuel storage arrangements where the fuel may not be uniformly mixed or
where
the fuel mixture might change over time as the vehicle is driven.
[0006] Direct measurement systems exist, but require installation of a
mechanism
inside, or in-line with, the fuel line. Repair, replacement, or adjustment of
such an
internal or in-line fuel composition measurement mechanism is problematic.
[0007] The prior art fails to provide a reliable, inexpensive, and accurate
system
and method of measuring the composition of fuel in a motor vehicle using a
system that
can be installed external to a fuel line, fuel tank, or the like.
SUMMARY
[0008] The present invention is directed to systems and methods which
accurately
measure the composition of fuel in a motor vehicle and more specifically the
alcohol
content of fuel in a motor vehicle, particularly ethanol, by means of a non-
intrusive fuel
composition sensor.
[0009] In particular, embodiments of the present invention may be used in FFVs
to
detect the percentage of ethanol content in the fuel. This information can be
constantly
reported to the EMS or Body Control Module of the FFV, allowing the EMS to
respond
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accordingly, thereby promoting performance, efficiency and/or the like.
Advantageously
the present invention provides immediate accurate ethanol content information
without
any direct contact with fuel, minimizing emissions, risk of fuel leak, risk of
major car
breakdown failure, and/or the like.
[0010] In accordance with various embodiments of the present invention, a flex
fuel
sensor may be deployed in conjunction with the fuel transfer line (e.g.
disposed around a
plastic fuel line), at the bottom or side of a fuel tank, or otherwise
disposed proximate to
the fuel.
[0011] In accordance with a method of the present invention a resonant circuit
is
resonated at a resonant frequency, an inductor of the resonant circuit is
positioned
proximate to liquid in a space and a capacitor of the resonant circuit is
positioned
proximate to the liquid in the space. A change in an electrical parameter
associated with
the resonant circuit caused by a variation in at least one property of the
liquid is
measured.
[0012] Therefore, a flex fuel sensor of the present invention may comprise a
resonant circuit, with a capacitor of the resonant circuit comprising plates
disposed
adjacent to a fuel space and an inductor disposed adjacent to the fuel space,
whereby the
fuel acts as a dielectric in the capacitor in a manner proportionate to the
constituents of
the fuel.
[0013] The space may be a liquid transmission line, a storage tank, or the
like, as
discussed above. In the case of a liquid transmission line, the capacitor of
the resonant
circuit might comprise a plurality of plates placed on either side of the
liquid transmission
line. or spaced apart semi-cylindrical conductive plates disposed about the
liquid
transmission line.
[0014] Positioning the inductor of the resonant circuit in close proximity to
the
space causes electromagnetic radiation to propagate into the liquid in the
space, whereby
the liquid acts as an electrical load to the resonant circuit in a manner
proportionate to the
constituents of the liquid.
[0015] In accordance with some embodiments of the present invention a signal
of a
constant frequency may be generated across a resonant circuit, which comprises
an
inductor and a PCB trace capacitor, capacitor plates, or the like.
Electromagnetic
radiation may be propagated into the fuel, such as the passing fuel in a fuel
transfer pipe.
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The conductivity and dielectric properties of the fuel may impact upon the
electromagnetic field and may change the capacitance of the capacitor, the
trace
capacitor, the capacitor plates or other such capacitive device or devices
which comprise
the resonant circuit. Such changes may be proportional to the constituents of
the fuel and
may, for example be representative of the alcohol/ethanol content in the fuel.
Such
changes may be detected by a microcontroller, or the like, and may be
communicated to a
second microcontroller, to the EMS, to a device external to the flex fuel
sensor, and/or
other device. Such communications may be asynchronous or may be synchronized
to an
external device, and may be triggered by a signal from an external device,
and/or the like
As such the present invention provides a non-invasive, cost effective
solution, well suited,
not only for original equipment applications but also for up-fit or retro-fit
or the like. The
present systems and methods are highly responsive and provide immediate
information
to, an EMS or similar device, allowing quick and accurate adjustments to be
made which
may facilitate improvement and/or maintenance of vehicle performance.
[0016] In accordance with embodiments of the present invention, a
substantially
sinusoidal RF signal of a constant frequency may be generated and coupled to a
resonant
LCR (inductance-capacitance-resistance) circuit. Alternatively or
additionally, a parallel
resonant circuit may be employed. An inductor, such as for example a coil of
the
resonant circuit, may be placed proximate a fuel line, fuel tank or the like,
causing
electromagnetic radiation to propagate into the fuel space. Alternatively or
additionally, a
capacitor of the resonant circuit may be placed around, adjacent to or
otherwise disposed
proximate to a fuel line, fuel tank or the like, causing electromagnetic
radiation to
propagate into the fuel space. Consequently, the liquid fuel inside the line
or tank acts as
an electrical load to the resonant circuit in a manner proportionate to the
constituents of
the fuel. The loading effect of the fuel may cause a shift in the resonant
frequency of the
circuit and/or a change in the Q (quality factor) of the resonant circuit. The
loading effect
of the fuel is determined by monitoring a change in one or more electrical
parameters
associated with the excited resonant circuit. For example, the voltage across
the resistor
in the resonant circuit can be monitored. Changes in this voltage are detected
and
analyzed by a system controller, the result of which is used to output a
signal indicative of
fuel composition. Alternatively or additionally, measurements may be taken
from the
capacitor/capacitors and/or the inductor/inductors comprising the resonant
circuit as
impacted by the loading effect of the fuel on the resonant circuit and/or the
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electromagnetic field. Such an impact may for example be detected by measuring
an
amplitude change in the frequency signal of the resonant circuit, a change in
the resonant
frequency of the resonant circuit and/or the like. Regardless, measurements
may take the
form of a digital and/or analogue, electrical, and/or magnetic signals.
[0017] The present systems and methods can sense and measure the composition
of
liquid in other transmission lines and/or containers and are not limited to
the examples
used in this description. The system can be used in a wide variety of
scientific, consumer,
industrial, and medical environments, as well as in vehicles as discussed
herein.
[0018] The present systems and methods may employ auto-calibration hardware
and software that enables a flex fuel sensor of the present invention to
determine an
optimum system operating frequency. In one embodiment of the present
invention, the
optimum system operating frequency is selected to be a frequency above or
below the
resonant frequency of the resonant LCR circuit. The choice of this operating
frequency
over the resonant frequency may allow for larger changes in voltage drop as
impacted by
changes in liquid composition. Preferably, the system of such embodiments is
tuned to
operate at a frequency between a lower and upper value.
[0019] In some embodiments of the present invention, auto-compensation is
provided to help ensure that the measured electrical parameter provides an
accurate
indication of the liquid composition in the fuel line, fuel tank, fuel
container, or the like,
independent of variations in operating conditions, such as variations in
ambient
temperature, humidity, pressure and/or the like.
[0020] By measuring fuel composition in-line, the present systems and methods
may provide an EMS or other engine control device dynamic, accurate fuel
composition
information regardless of the fuel storage system employed and ongoing mixing
of fuel in
saddle tanks or similar storage arrangements.
[0021] Embodiments of the present invention may include a physical or wireless
data interface to facilitate external communication or transmission of raw
data
measurements, encoded measurements, compensated measurements, and/or the like
from
a flex fuel sensor to a central controller in the vehicle. Such information
may be
communicated: periodically; in response to a change; by request from the
central
controller; by request from an external device such as a diagnostic device;
and/or in other
manners.
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[0022] The foregoing has outlined rather broadly the features and technical
advantages of the present invention in order that the detailed description of
the invention
that follows may be better understood. Additional features and advantages of
the
invention will be described hereinafter which form the subject of the claims
of the
invention. It should be appreciated by those skilled in the art that the
conception and
specific embodiment disclosed may be readily utilized as a basis for modifying
or
designing other structures for carrying out the same purposes of the present
invention. It
should also be realized by those skilled in the art that such equivalent
constructions do not
depart from the spirit and scope of the invention as set forth in the appended
claims. The
novel features which are believed to be characteristic of the invention, both
as to its
organization and method of operation, together with further objects and
advantages will
be better understood from the following description when considered in
connection with
the accompanying figures. It is to be expressly understood, however, that each
of the
figures is provided for the purpose of illustration and description only and
is not intended
as a definition of the limits of the present invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] The accompanying drawings, which are incorporated in and fonm part of
the
specification in which like numerals designate like parts, illustrate
embodiments of the
present invention and together with the description, serve to explain the
principles of the
invention. In the drawings:
[0024] FIGURE 1 is a perspective view of an embodiment of a flex fuel sensor
of
the present invention deployed in conjunction with a fuel line;
[0025] FIGURE 2 is an exploded perspective view of the flex fuel sensor of
Figure
1;
[0026] FIGURE 3 is a rear side perspective view (relative to the perspective
of
Figures 1 and 2) of the PCB and capacitor plates of the flex fuel sensor of
Figure 1; and
[0027] FIGURE 4 is an exploded perspective view of another embodiment of a
flex
fuel sensor of the present invention, showing the PCB and semi-cylindrical
capacitors.
DETAILED DESCRIPTION
[0028] Figures 1 and 2 show an embodiment of flex fuel sensor 100 of the
present
invention disposed in conjunction with fuel line 102, such as mounting flex
fuel sensor
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housing 115 to base plate 117, encompassing fuel line 102. Alternative
embodiments call
for mounting a flex fuel sensor of the present invention to the side or bottom
of a fuel
tank. Generally, fuel line 102 or the aforementioned fuel tank is comprised of
a non-
conductive material such as plastic.
[0029] Figure 3 illustrates an embodiment of PCB 105 and capacitor plates 110
and
112 of flex fuel sensor 100. Embodiments of flex fuel sensor 100 house PCB 105
in
housing 115. PCB 105 may mount and/or define a controller, the controller
including an
RF generator and an analog-to-digital converter (ADC). PCB 105 might also
include an
antenna driver having output terminals, and input terminals, coupled to the RF
generator
and a resonant circuit coupled to the antenna driver and having an inductor
positioned
proximate a liquid in a container or fuel transmission line 102.
[0030] A flex fuel sensor of the present invention may comprise a resonant
circuit,
with a capacitor of the resonant circuit comprising plates disposed adjacent
to a fuel space
and an inductor disposed adjacent to the fuel space, whereby the fuel acts as
a dielectric
in the capacitor in a manner proportionate to the constituents of the fuel.
[0031] In the embodiment of Figures 1-3 a capacitor of an LCR circuit takes
the
form of a plurality of capacitor plates (110, 112). By placing an inductor of
the resonant
circuit in close proximity to a fuel line, electromagnetic radiation may be
propagated into
a fuel space defined within the line. Whereby, fuel in the line acts as an
electrical load to
the resonant circuit in a manner proportionate to the constituents of the fuel
in the line.
The conductivity and dielectric properties of the fuel change the capacitance
of the trace
capacitor/capacitor plates 110 and/or 112.
[0032] In illustrated embodiment 400 of Figure 4, a capacitor of an LCR
circuit
takes the form of a plurality of semi-cylindrical shaped capacitors 410, 420
and 430 of
flex fuel sensor 100. This embodiment of the present invention may employ two
semi-
cylindrical capacitors giving a capacitive effect, or alternatively may have
additional
capacitors such as illustrated in order to increase the capacitance in the
resonant circuit.
Such semi-cylindrical shaped capacitors may fit into molded housing 440 and
may be
fixed around the fuel line using a sealing material such as for example a
thermo plastic
elastomer seal or other appropriate sealing material to adequately prevent
contaminants
and/or air between flex fuel sensor 100 and fuel line 102.
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[0033] The present invention measures properties of a liquid, such as engine
fuel.
These properties are preferably electrical properties and a measured change in
the
electrical parameter of the liquid is a function of a variation in the
electrical property of
the liquid. Where the liquid is a fuel, the variation in electrical property
may be a
function of fuel composition. Measurements of electrical properties may
include
measuring a change in voltage at the resonant circuit and/or measuring a
change in the
resonant frequency of the resonant circuit.
[0034] Hence in accordance with a method of the present invention a resonant
circuit is resonated at a resonant frequency, an inductor of the resonant
circuit is
positioned proximate to liquid in a space and a capacitor of the resonant
circuit is
positioned proximate to the liquid in the space. A change in an electrical
parameter
associated with the resonant circuit caused by a variation in at least one
property of the
liquid is measured.
[0035] In various embodiments of the present invention, the aforementioned RF
generator generates an RF signal at an operating frequency of the resonant
circuit and the
antenna circuit is electrically coupled to the RF generator. The resonant
circuit preferably
has a frequency response curve centered around a resonant frequency. The
controller
may be operatively connected to the RF generator and to the antenna circuit
and may be
functional to cause the operating frequency of the RF generator to be
proximate to the
resonant frequency of the resonant circuit, and to measure a change in an
electrical
parameter associated with the resonant circuit as may be impacted by changes
in for
example the concentration of alcohol in the liquid passing through fuel line
102 or stored
in the fuel tank or fuel container.
[0036] In an embodiment of the present invention changes in the properties of
the
fuel, such as for example changes in the dielectric properties of the fuel,
the conductivity
of the fuel, and/or the like, which may result from changes in the
constituents of the fuel,
may manifest as changes in the resonant frequency and/or properties of the
resonant
circuit. Such a change may be detected by sweeping between a first frequency
and a
second frequency to detect the new resonant frequency of the resonant circuit.
Alternatively or additionally, changes in the properties of the fuel may
manifest as
changes to the amplitude of the resonant frequency signal of the resonant
circuit.
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[0037] The controller or similar circuitry of sensor 100 is preferably
functional to
monitor and/or communicate the measured change in the electrical parameter,
such as via
conductors 125 of sensor electrical connector 130. In particular, the
controller may be
further functional to convert the measured change in the electrical parameter
to an alcohol
concentration signal and to communicate the alcohol concentration signal to a
flex fuel
vehicle engine management system EMS, an external receiving device or the
like.
[0038] Preferably, the present invention allows for calibrating the operating
frequency of the RF signal to compensate for physical and/or electrical
properties of the
respective fuel line or container. This calibration may be carried out
automatically. Such
calibration might include adjusting the operating frequency of the RF signal
so that an
alcohol concentration sensing window is defined on a substantially linear part
of a
frequency response curve proximate the resonant frequency of the resonant
circuit. The
resonant circuit may be a series resonant circuit, and the controller may be a
calibration
module operative to cause the operating frequency of the RF generator to be on
a
substantially linear portion of the frequency response curve above the
resonant frequency.
Alternatively or additionally, calibrating the operating frequency might
include sweeping
the operating frequency of the RF signal in a range between a first frequency
and a
second frequency and measuring a parameter of the resonant circuit as the
frequency of
the RF signal is swept. In accordance with such embodiments, the controller
might
include a compensation module functional to adjust the alcohol concentration
signal for
changes in ambient temperature.
[0039] Thus, a change in voltage at the resonant circuit and/or a shift in the
resonant frequency of the resonant circuit may be measured. The measurement
may be
carried out by sweeping between a first frequency and a second frequency to
identify a
resonant frequency of the resonant circuit. Also, the resonant frequency of
the resonate
circuit may be compensated for physical and/or electrical properties of a
respective fuel
line or container defining the space. This calibration may take place
automatically. For
example, calibration may be carried out by sweeping between a pair of
frequencies to
identify a resonant frequency of the resonant circuit as impacted by the space
alone.
Then, the measurement may be made by sweeping between a different, or the
same, pair
of frequencies to identify a resonant frequency of the resonant circuit as
changed by the
liquid in the space.
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[0040] Although the present invention and its advantages have been described
in
detail, it should be understood that various changes, substitutions and
alterations can be
made herein without departing from the spirit and scope of the invention as
defined by the
appended claims. Moreover, the scope of the present application is not
intended to be
limited to the particular embodiments of the process, machine, manufacture,
composition
of matter, means, methods and steps described in the specification. As one of
ordinary
skill in the art will readily appreciate from the disclosure of the present
invention,
processes, machines, manufacture, compositions of matter, means, methods, or
steps,
presently existing or later to be developed that perform substantially the
same function or
achieve substantially the same result as the corresponding embodiments
described herein
may be utilized according to the present invention. Accordingly, the appended
claims are
intended to include within their scope such processes, machines, manufacture,
compositions of matter, means, methods, or steps.
