U.S. patent application number 16/576541 was filed with the patent office on 2020-01-09 for radio frequency process sensing, control, and diagnostics network.
This patent application is currently assigned to Filter Sensing Technologies, Inc.. The applicant listed for this patent is Filter Sensing Technologies, Inc.. Invention is credited to Leslie Bromberg, Alexander Sappok.
Application Number | 20200014470 16/576541 |
Document ID | / |
Family ID | 54767504 |
Filed Date | 2020-01-09 |
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United States Patent
Application |
20200014470 |
Kind Code |
A1 |
Sappok; Alexander ; et
al. |
January 9, 2020 |
Radio Frequency Process Sensing, Control, and Diagnostics
Network
Abstract
A sensing and control system and method is disclosed, which
utilizes cavity resonance and waveguide measurements to directly
monitor process state variables or detect changes in the state of a
system and provide direct in situ feedback control top optimize the
process. The same system may be used to monitor a number of
different process parameters including the composition, amount,
distribution, and physical or chemical properties of a material, or
to monitor the state or health of a system or sub-system. The
system is broadly applicable to wide range of systems and process
including ranging from engines and exhaust systems to production
plants.
Inventors: |
Sappok; Alexander;
(Cambridge, MA) ; Bromberg; Leslie; (Sharon,
MA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Filter Sensing Technologies, Inc. |
Malden |
MA |
US |
|
|
Assignee: |
Filter Sensing Technologies,
Inc.
Malden
MA
|
Family ID: |
54767504 |
Appl. No.: |
16/576541 |
Filed: |
September 19, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
14733486 |
Jun 8, 2015 |
10425170 |
|
|
16576541 |
|
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|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F01N 11/00 20130101;
F02D 41/0235 20130101; F01N 2560/12 20130101; F01N 2550/02
20130101; F01N 2560/021 20130101; H04B 17/00 20130101; H04B 17/309
20150115; F01N 2900/1402 20130101; F02D 41/1444 20130101; Y02T
10/47 20130101; F01N 2550/04 20130101; F01N 2560/026 20130101 |
International
Class: |
H04B 17/00 20060101
H04B017/00; H04B 17/309 20060101 H04B017/309 |
Claims
1. A radio frequency process control system comprising: a plant or
machine requiring at least one input and generating at least one
output stream; a module, conduit, or component in the plant or
machine forming a resonant cavity for containing radio frequency
signals; a radio frequency probe in the resonant cavity of the
module, conduit, or component to transmit and/or receive the radio
frequency signals; and a radio frequency control unit, in
communication with the radio frequency probe, to (i) monitor at
least a change in the phase of said radio frequency signals
transmitted and/or received through the resonant cavity of the
module, conduit, or component and (ii) measure more than one
parameter selected from the group including amount of a material,
type of the material, spatial distribution of the material,
physical or chemical properties of the material, environmental
conditions, position or level, cavity integrity, or rate of change
of the parameter, based on at least a measurement of the change in
the phase of said radio frequency signals transmitted and/or
received through the resonant cavity of the module, conduit, or
component, the radio frequency control unit containing the
components for transmitting, detecting, controlling, modulating,
and monitoring the radio frequency signals transmitted and/or
received by the radio frequency probe.
2. The system of claim 1, wherein said module, conduit, or
component is selected from the group including catalyst, substrate,
filter, cavity, or housing, or engine.
3. The system of claim 1, wherein said radio frequency control unit
determines leakage of a material through said output stream, based
on measured material accumulation in said output stream and known
emissions of said material from said machine.
4. The system of claim 1, wherein said radio frequency control unit
determines an amount, quality or composition of a material in said
module, conduit, or component.
5. The system of claim 4, wherein said material is selected from
the group consisting of fuel, oil, coolant, air, urea, and EGR
gas.
6. The system of claim 1, wherein said module, conduit, or
component comprises an engine of the plant or machine, and the
radio frequency probe is disposed in a cylinder of said engine, to
monitor one or more engine parameters.
7. The system of claim 6, wherein the one or more engine parameters
are selected from the group consisting of position of piston,
quality of combustion process, emissions processed by said
combustion process, quantity of fuel injected, temperature and
pressure.
8. A radio frequency sensing system, comprising; a radio frequency
probe to transmit and/or receive radio frequency signals within a
cavity of a machine, the first radio frequency probe extending in
the cavity and the cavity containing the radio frequency signals; a
timing device; and a radio frequency control unit, in communication
with the radio frequency probe and the timing device, to monitor at
least a change in the phase and amplitude of the transmitted and/or
received radio frequency signals and to measure a change in said
determined process parameter based on inputs from said timing
device and a measurement of the change in the phase and amplitude
of the transmitted and/or received radio frequency signals, and to
initiate an action based on said change in said determined process
parameter, the radio frequency control unit containing all of the
components for transmitting, detecting, controlling, modulating,
and monitoring the radio frequency signals transmitted and/or
received by the radio frequency probe.
9. The radio frequency sensing system of claim 8, wherein said
radio frequency control unit provides diagnostic information to an
operator based on said change in said determined process
parameter.
10. The radio frequency sensing system of claim 9, wherein said
diagnostic information is selected from the group consisting of an
indication of a failure of a filter element, an indication of a
failure of a catalyst element, an indication of a broken conduit,
and an indication of a blockage or obstruction in said machine.
11. The radio frequency sensing system of claim 10, wherein the
radio frequency control unit modifies operation of said machine
based on said change in said determined process parameter.
12. The radio frequency sensing system of claim 11, wherein said
radio frequency control unit modifies fueling, air flow, boost
pressure, EGR rates, injection timing, urea or hydrocarbon
dosing.
13. A machine, comprising: at least one input and generating at
least one output stream; a radio frequency probe mounted in a
cavity within said machine to transmit and/or receive radio
frequency signals contained in and propagated through the cavity
within said machine, the radio frequency probe being operable at a
specified frequency or range of frequencies which may vary
depending on the type, location, and measurement application of the
radio frequency probe; and a radio frequency control unit, in
communication with the radio frequency probe, to monitor a change
in at least the phase of said radio frequency signals transmitted
and/or received through the cavity, measure at least one parameter,
based on at least a measurement of the change in the phase of said
radio frequency signals transmitted and/or received through the
cavity, and initiate an action based on said at least one measured
parameter.
14. The machine of claim 13, wherein at least a first radio
frequency probe monitors said input and at least a second radio
frequency probe monitors said output stream.
15. The machine of claim 13, wherein said radio frequency control
unit modifies an operation of said machine based on said at least
one measured parameter.
16. The machine of claim 13, wherein said radio frequency control
unit alters an operator of a fault condition based on said at least
one measured parameter.
17. The machine of claim 13, wherein said radio frequency control
unit is in communication with a timing device and said radio
frequency control units determines a rate of change of said at
least one measured parameter.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This patent application is a continuation application that
claims priority and benefit of the filing date of U.S. patent
application Ser. No. 14/733,486 filed on Jun. 8, 2015, the
disclosure and contents of which is expressly incorporated herein
in its entirely by reference.
BACKGROUND OF THE INVENTION
[0002] Radio frequency measurements utilizing cavities and
waveguides may be used in a wide range of process control systems,
to monitor the state of the system, detect faults, and provide
adaptive feedback control to optimize the process. Microwave cavity
and waveguide measurements are useful to provide information on the
state of the system in situ, without the need for sample removal
and subsequent analysis, as is the case with many existing
systems.
[0003] Examples to illustrate the broad applicability of radio
frequency-based cavity and transmission measurement systems
include: engines and engine systems, power plants, chemical plants,
petroleum extraction and processing, and process sensing and
controls in any number of systems.
[0004] Current sensing and control networks for process control
systems suffer from a number of limitations, which are briefly
summarized as follows:
[0005] First, in many systems there is a need to physically remove
a sample from a discrete point in the system at specified time
intervals in order to subsequently analyze the sample. These
measurements incur a time delay between the time when the sample is
collected and when the sample is analyzed, which may range from a
few minutes to weeks or even months in some cases. The process of
removing the sample may introduce additional variability in the
measurements, which may be related to sample handling, the sampling
method employed, and the location and timing of the sample
extraction, among others. In addition to introducing potential for
added variability, measurements based on extracted samples provide
limited information corresponding only to the sample
characteristics or state at the time of sample extraction from the
system. The time delay between sample collection and receipt of
measurement results does not allow for efficient process
optimization or detection of faults or error conditions when they
occur.
[0006] Second, many processes employ sensors to monitor the state
or characteristics of various system parameters in-line. Examples
of these types of sensors include temperature sensors, pressure
sensors, moisture sensors, composition sensors such as gas sensors,
particle sensors, and similar sensors. Most of these sensors,
however, only provide a measurement of the process parameters in
close proximity to the sensor or require close contact between the
material being measured and the sensing element itself. Use of
these types of sensors greatly restricts the type of parameters
which may be directly monitored, and also limits the measurements
to discrete points in the system where the sensors are located.
[0007] Third, in order to measure various different characteristics
of a system, many different types of sensors are generally
required, each employing a different measurement principle. For
example, temperature, pressure, and gas composition sensors
(oxygen, NOx, ammonia, PM) may be used in an exhaust system. Use of
many different types of sensors, each with their own specific
requirements and response characteristics, increases the cost and
complexity of sensing and control networks.
[0008] Fourth, despite the prevalence of a large number of sensors,
oftentimes the actual state variable of interest may not be
measured directly, and must be indirectly estimated based on
measurements from available sensors. For example, the amount of
material accumulated on a filter may be inferred from pressure drop
measurements across the filter, or the amount of a gas adsorbed on
a catalyst may be inferred from gas composition sensors monitoring
gas composition upstream or downstream of the catalyst. In another
example, measurements of upstream and downstream process parameters
may be used to infer or indirectly detect a failure of malfunction
of a device, such as a filter or catalyst, using conventional
sensors. However, in these cases, direct measurement of the
required state variable, namely the amount of material on the
filter or the quantity of a species adsorbed on a catalyst can not
be measured directly. Such indirect estimates suffer from poor
accuracy, and are cumbersome and time-consuming to calibrate.
[0009] Fifth, in many cases, there is a need to detect system
faults or malfunctions when they occur, or preferentially to detect
signs of faults or malfunctions before they occur. In particular,
certain components in the system may mask signs of faults or
malfunctions making them difficult to detect through conventional
sensing means. For example, exhaust particulate filters may mask
observable signs of impending engine faults, such as smoke related
to high oil or fuel consumption or water vapor due to a coolant
leak. Such faults are difficult to detect using conventional
sensors, or may be easily mistaken or confused, using measurements
from conventional sensors.
[0010] Sixth, many conventional sensors such as electrochemical gas
sensors, accumulation type soot or particle sensors, and the like
require contact or direct interaction of the sensing element with
the material being measured. Such sensors suffer from fouling,
poisoning, or aging through the build-up of contaminant material on
the sensing element, which needs to be avoided.
[0011] It is, thus, desired to have an improved sensing and control
network. Such an improved network may exhibit one or more of the
following attributes: (i) direct measurement of the state variable
or variables of interest, (ii) in-situ measurements, (iii) fast
response time, (iv) the ability to sample a multiple large volumes
(i.e., selectively choosing the region in the device that is being
sampled) and/or detect changes in the system which may not be in
close proximity to the sensing element, (v) improved measurement
accuracy and feedback control, (vi) non-contact sensing methods
whereby the sensing element does not need to come in contact with
the material or processes being interrogated, and (vii) a
simplified and less cumbersome measurement system.
[0012] It is further desirable to measure the deposition of
materials on surfaces of process systems, such as walls of the
device or reactor, in one example, that are detrimental to the
operation of the device (such as deposits on cladding of furnaces
or biofilms in chemical reactors).
[0013] Therefore, an improved process sensing and controls network
is needed, which will have considerable utility for a broad range
of applications and fields of uses.
SUMMARY OF THE INVENTION
[0014] A sensing and control system and method is disclosed, which
utilizes cavity resonance and waveguide measurements to directly
monitor process state variables or detect changes in the state of a
system and provide direct in situ feedback control to optimize the
process. The same system may be used to monitor a number of
different process parameters including the composition, amount,
distribution, and physical or chemical properties of a material, or
to monitor the state or health of a system or sub-system, by
monitoring the changes in the dielectric properties of the cavity
or waveguide. The system is broadly applicable to wide range of
systems and process ranging from engines and exhaust systems to
production plants.
BRIEF DESCRIPTION OF THE FIGURES
[0015] FIG. 1 represents a plant or process system, such as an
engine and exhaust system in one embodiment, but may be any plant
or process control system, monitored and controlled by a radio
frequency system.
[0016] FIG. 2 represents a radio frequency probe in one
embodiment.
[0017] FIG. 3 represents a process flow diagram for a radio
frequency-based control system, which may be an engine system in
one embodiment, but may be any plant or process control system.
DETAILED DESCRIPTION OF THE INVENTION
[0018] FIG. 1 depicts a plant such as an engine and exhaust system
monitored by a radio frequency system. The plant may be any type of
plant, such as a chemical plant, food processing plant, power
plant, refinery, distillery, or any type of plant or process. The
plant or reactor may be a flowing reactor, or it could be a batch
reactor.
[0019] A machine 102, such as an engine in one example or a plant
in another example, may have outlet connection, such as a conduit
106, which may be connected to various components and sensors.
Machine 102 may generate an output stream, such as an exhaust
stream, or any other stream, which may or may not be directed
through conduit 106. In one embodiment, conduit 106 may be
connected to a first module 108 and a second module 110. In one
embodiment, modules 108 and 110 may be cavities, such as resonant
cavities, or may be waveguides in another embodiment.
[0020] In a particular embodiment, module 108 may be particulate
filter housing, such as a gasoline particulate filter or diesel
particulate filter housing. Module 108 may contain multiple
elements, such as a catalyst element 112, which may be a three-way
catalyst (TWC), oxidation catalyst (OC), selective catalytic
reduction catalyst (SCR), lean NOx trap (LNT), or any type of
catalyst, and a filter element 114 such as a particulate filter. In
one embodiment, module 110 may be a catalyst housing, containing a
catalyst element 116 such as an SCR, LNT, TWC, ammonia storage,
hydrocarbon trap, or any other type of catalyst. In another
embodiment no modules 108 or 110 may be present and in another
embodiment, more than one module may be present. Each module may
contain one or more elements, such as catalysts, filters or
membranes in one example, or no internal elements in another
example.
[0021] Conduit 106 may also contain one or more internal elements
118 such as a filter, catalyst, mixer, diffuser, or other element,
which may be located at any position within conduit 106. Radio
frequency probes, 120, 122, 124, and 126 such as rod antennas, loop
antennas, waveguides, dielectric resonators, or any other suitable
probes for launch or receiving radio frequency signals may also be
mounted at any position along conduit 106 or on modules 108 or
110.
[0022] Additional conduits 138 may be connected to machine 102 such
as intake ducts, fuel lines, oil lines, coolant lines, or other
similar conduit, such as a duct, tube, or pipe. Conduit 138 may
supply an inlet stream to plant or machine 102. Conduit 138 may
contain one or more modules 136 such as an air filter housing, oil
filter housing, fuel filter housing, radiator, EGR cooler, fuel
tank, oil tank, urea tank or any other type of module, cavity, or
waveguide. Radio frequency probes 128 or 130 may or may not be
installed in conduit 138 or module 136.
[0023] Although FIG. 1 depicts machine 102 as having one inlet
conduit 138 and one outlet conduit 106, machine 102 may contain
more than one inlet conduit, more than one outlet conduit, or no
inlet conduits or no outlet conduits. Additionally, each conduit,
if present, may be consist of a network for connections, passages
and conduits (not shown) such as a pipe or duct system or network
consisting of interconnected conduits of varying sizes and
geometries. Additional modules, such as multiple modules 136, 108,
110, or 118 may or may not be present in inlet our outlet
conduits.
[0024] Radio frequency probe 132 may be installed in one component
of machine 102 such as a cylinder 134 in the case of an engine.
Additional probes, not pictured, may also be installed in other
components of machine 102. Radio frequency probes 120 122, 124,
126, 128, 130, and 132 may be connected to a control unit 104. In
one embodiment, a single control unit 104 may be used to monitor
and control all radio frequency probes, or more than one control
unit 104 may be used. In one embodiment, the number of radio
frequency probes may be more or less than those depicted in FIG. 1.
Additional sensors, such as temperature sensors, pressure sensors,
gas composition sensors (NOx, PM, Oxygen, Ammonia) or any other
types of sensors may be used, which are not shown in FIG. 1. These
ancillary sensors may be connected to control unit 104 or another
control unit, such as an engine, plant, or process control unit,
also not shown, which may be in communication with control unit
104.
[0025] Control unit 104 may be connected to machine 102 or to
another control unit, such as an engine control unit or process
control unit (not shown). Control unit 104 may contain a processing
unit and computer readable storage medium 140 containing
instructions, algorithms, data, lookup tables, and any other
information necessary to control the connected sensors and machine.
Control unit 104 may contain connection 142 which may be a
communication connection, such as Ethernet, USB, analog, CAN,
serial, or some other type of connection or power connection.
Connection 142 may be connected to the plant control unit, to the
engine control unit (ECU) in a vehicle, or to signal to the
operator of the status of the unit and of potential problems.
[0026] Control unit 104 may contain hardware or electronics used to
transmit radio frequency signals, such as an oscillator, as well as
a detector for detecting radio frequency signals such as a diode or
power detector or any other type of detector. Control unit 104 may
further contain mixers, splitters, directional couplers, switches,
and other components for controlling, modulating, transmitting, and
monitoring radio frequency signals.
[0027] Control unit 104 may be configured to transmit and receive
radio frequency signals through any of the radio frequency probes
120 122, 124, 126, 128, 130, or 132. Each probe may be
independently controlled to transmit, receive, or transmit and
receive radio frequency signals, such as in a multi-port network
including transmission, reflection, and transmission or reflection.
For example, probe 122 may transmit a radio frequency signal which
may be detected by one or more probes 126, 124, 122, or 120. In
another example, probe 126 may transmit a radio frequency signal
that may be received only by probe 126 or by probe 124. Any number
of probes may be used and one probe may or may not communicate with
another probe.
[0028] Control unit 104 may further be configured to transmit and
receive radio frequency signals through any of the radio frequency
probes 120 122, 124, 126, 128, 130, or 132 at the same time or at
different times. The probes may operate (transmit/receive)
continuously, at specified time intervals, or on demand, based on a
command or request from control unit 104. Each probe may operate at
a specified frequency or range of frequencies, which may vary
depending on the type, location, and measurement application of
each probe.
[0029] The radio frequency signal characteristics may depend on the
probe being used and the variable being interrogated. Thus, one
probe may use a different frequency range than a second probe, as
the resonant/transmission characteristics of the modules 108, 110,
or 136, or the conduit 106 or 138 may be different, as well as a
desired different frequency range for improved characterization of
the variable being interrogated by the different probe (i.e.,
better selectivity or sensitivity, which could be frequency
dependent). It is possible that the same probe uses multiple
frequency ranges, either to improve detection of one variable, or
to interrogate the unit for different variables.
[0030] The probing of the different variables in the different
modules or in the same module can occur at different times, with
scans by the control unit 104 sending signals to different probes
at different times. It is possible to use different transmitted
power (generated by control unit 104) when probing different
cavities, or different power when probing for the different
frequency ranges for a single probe. Thus, control unit 104 at
different times can generate radio frequency signals of constant or
variable amplitude, and with a different range of frequencies,
being sent to selected radiating antennas, and, at a given time,
receive signals from one or multiple receiving antennas.
[0031] In another example, signals generated by a probe 120 in an
SCR, LNT, TWC, ammonia storage, hydrocarbon trap or any type of
catalyst can be detected upstream or downstream for the module by a
separate probe, such as 122, 124, 126, 132, 130, or 128, or the
signal may be detected by the same transmitting probe 120 in this
example. Alternatively, a signal can be transmitted by probe 128
and detected by probe 130, where module 136 is an air filter
housing, an oil or fuel filter housing, EGR cooler, fuel tank, oil
tank, SCR tank, or other type of filter, tank, enclosure, or
catalyst. Any configuration of probes and conduit or modules may be
used.
[0032] The radio frequency signals may span a frequency range such
as to establish one or more resonant modes, or may span a frequency
range that does not include a resonant mode, or may be at a single
frequency. The various modules 108, 110, 136, and conduit 106 or
138, or machine components 134 may serve as microwave resonant
cavities or waveguides, or may contain resonators (such as
dielectric resonators) that can be used to sample a limited region
of the device being monitored. The radio frequency signal,
including resonance curve, absolute amplitude, relative amplitude
(i.e., normalized to the power being transmitted by the probe),
phase, resonant frequency shift, frequency shift, or some
derivative thereof including local or absolute maxima or minima,
frequency shift, phase shift, average value, quality factor,
summation, area, peak width, or other parameter may be correlated
to the state of the system and used to monitor changes in the
loading state of the system. Changes in the dielectric properties
within the cavities or waveguides may be used to monitor or detect
one or more of the following parameters: [0033] 1. Amount of
Material: such as the amount of a solid, liquid, or gas-phase
component contained within or flowing through the cavity or
waveguide, or escaping or leaking from the cavity or waveguide. In
one example, the amount of soot or ash collected on a filter or the
amount of a gas phase component adsorbed on a catalyst may be
detected. Changes in the loading or storage state of a catalyst,
filter or membrane may also be detected, where the loading state is
due to the accumulation or loss of a solid, liquid, or gas phase
component. [0034] 2. Type of Material: such as the composition of a
blend of more than one type of material or species. In one example,
liquid blends may be detected, such as the presence of water in
fuels, biodiesel and petroleum diesel blends, ethanol and gasoline
blends, coolant and water blends, soot particles in a gas, soot
particles in oil, changes in the aging, oxidation or state of a
liquid, such as a fuel or oil, soot and ash blends, SOF, SOL, ash
and carbon fractions of particles, or any other type of blend.
[0035] 3. Spatial Distribution: such as the distribution of
material collected on filters, adsorbed on catalysts, deposited on
the walls or surfaces of a cavity or waveguide, or blends of
various components in a cavity or waveguide. [0036] 4. Physical or
Chemical Properties of a Material: where the dielectric properties
of a material are a function of the chemical state, such as the
oxidation or reduction state, polarity, pH, conductivity or
resistance, or other chemical property (due, for example, to
chemisorption), or where the dielectric properties of a material
are a function of physical properties such as the density,
structure, phase, or other physical properties. [0037] 5.
Environmental Conditions: where the dielectric properties of a
material are a function of environmental conditions such as the
temperature, pressure, humidity, or other related factors. [0038]
6. Position or Level: such as the position of a piston within a
cylinder, crank angle, linear or rotational position, or the volume
of a liquid in a tank, reservoir, or conduit such as a fuel tank,
oil sump, urea tank, or any other tank or reservoir or pipe or
hose. [0039] 7. Cavity or Waveguide Integrity: where changes in the
material comprising the walls or structure of the cavity or
waveguide affect the radio frequency signal, such as through the
build-up or accumulation of material on the cavity or waveguide
surfaces, the loss or escape of material from the cavity or
waveguide surfaces, or changes in the cavity or waveguide surfaces
such as cracking, thinning, fatigue, stress, the creation of holes,
changes in the system geometry, or separation of connections such
as flanges, couplings, and the like. [0040] 8. The rate of change
of a process parameter: Time-resolved measurements of the radio
frequency signal enable the derivative or change in the signal as a
function of time to be determined. Such measurements can provide
information on the rate of change of the processes described in
items 1-7.
[0041] The above list illustrates several major categories of
parameters that may be monitored using radio frequency means, but
is by no means exhaustive. Many other parameters may also be
monitored, as long as the parameters affect the dielectric
properties of the cavity or waveguide.
[0042] Control unit 104 may transmit and receive signals from one
or more radio frequency probes to monitor the state of various
system components and functions. In one example, machine 102 is an
engine such as an internal combustion engine, although machine 102
may be any type of machine, process, or plant that may be
characterized by performing some function on at least one input and
producing at least one output. In this example, module 136 is an
air filter, an oil filter, a fuel filter, a radiator, and EGR
cooler, an intercooler, tank or reservoir, or similar device and
probe 128 is used to monitor the state of the device, such as the
loading state of the filter or the deposition or buildup of
material in the element, or the amount, quality or composition of
the material in module 136 such as the amount, quality or
composition of the fuel, oil, coolant, air, urea, EGR gas, or other
material. In one example, probe 128 may be used to detect water,
sulfur levels, oxidation state, soot buildup, a change in base
number, or some other characteristic of the material within or
passing through module 136.
[0043] The same measurements described in reference to module 136
and probe 128 may also be conducted in conduit 138 by means of
probe 130. In this case, conduit 138 may be a pipe, tube, hose, or
conduit for fuel, air, coolant, hydraulic fluid, urea, EGR line or
cooler, or some other material. The measurements may be related to
the material composition, amount, characteristics, or other
properties.
[0044] In another example, probe 132 may be mounted in one or more
engine cylinders and used to measure the position of the piston
within the cylinder, the quality of the combustion process, the
emissions produced by the combustion process, the quantity of fuel
injected, or any other parameter, such as temperature or pressure.
Probe 132 may be mounted in other locations to monitor position
within other types of actuators, such as linear or rotational
actuators, or void volume in tanks and reservoirs such a liquid
tanks for fuel tanks or urea tanks or oil or coolant tanks, in
other examples.
[0045] In yet another example, probes 126 or 124 may be used to
monitor changes in the dielectric properties within module 108.
Although two probes are shown, only one probe or more than one
probe may be used in reflection, transmission, or some combination
of the two. The probes may or may not be contained within module
108. In one embodiment, module 108 is a particulate filter housing
containing a particulate filter 114 and a catalyst element 112.
Module 108 may contain only a filter or a catalyst, or multiple
elements, such as multiple filters and catalysts. The elements
within module 108 such as catalyst element 112 or particulate
filter 114 may be monitored using probes 126 or 124 in order to
determine the state of the filter or catalyst, such as the loading
state, aging, poisoning such as by sulfur, ash or soot accumulation
or distribution, and the health or integrity of the catalyst
element 112 or filter element 114 or module 108.
[0046] In addition, time-resolved measurements of the state of
module 108, catalyst element 112 or filter element 114 may be used
to determine the rate of material inflow or outflow from the module
using probes 126 or 124. In one example, module 108 may be a
particulate filter housing and the quantity of accumulated soot on
the filter 114 may be determined by radio frequency measurements
using probes 126 or 124, such as by monitoring phase, amplitude, or
some derivative parameter or combination thereof. In this example,
the radio frequency signal may be sampled at a rate faster than 1
sample per second in one embodiment, but may be faster or slower.
The derivative of the radio frequency signal, or difference in the
signal between successive measurements in time, provides an
indication of the rate of change of soot accumulation on the filter
element 114 in this example. In this manner, the entire filter
element 114 may serve as an accumulation soot sensor, to determine
the rate of soot accumulation on the filter element 114, not just
the total accumulation.
[0047] In one example, the combined filter containing module 108
and probes 126 or 124 may function as an engine-out soot sensor,
and provide engine feedback control or diagnostic information based
on the rate of change of soot accumulation on the filter 114
contained within module 108. Soot oxidation models may or may not
be used to compensate for soot oxidation on the filter 114 under
certain conditions in this example.
[0048] In another example, module 108 may not be a particulate
filter housing but may be any type of catalyst, or combined filter
and catalysts system, such as a three-way catalyst coated filter,
oxidation catalyst coated filter, or selective catalytic reduction
coated filter. In a similar manner, the entire catalyst or catalyst
coated filter may be used as a gas sensor to determine the inflow
rate of a specific gas species, such as NOx, NH.sub.3, HC, CO, or
some other species based on the monitored rate of change of the RF
signal indicative of the adsorption of the specific gas species on
the catalyst surface or other interaction of the gas species of
interest with the catalyst. The monitored material need not be in
the gas phase or particle phase, as in the above examples, but may
also be a liquid.
[0049] In one example, the monitored radio frequency parameter may
be determined from absolute or relative amplitude or phase
measurements or some derivative thereof, such as a maximum or
minimum value, average value, frequency shift, peak or resonance
width at a given power level, quality factor, or a related
parameter. The parameter may be determined at a fixed frequency, or
over a continuous or discontinuous range of frequencies. The
frequencies my or may not include resonant conditions.
[0050] The rate of change, (.DELTA./t), of one or more measured
radio frequency parameters, P, may be computed at a specific time,
t, as follows:
(.DELTA./t)=(P.sub.t-i-P.sub.t)/((t-1)-t) Equation 1
where the notation (t-1) indicates a measurement of the parameter P
at a previous time and the subscript (t) indicates the current
measurement time. In this manner, the module 108 or a portion
thereof can be used to determine the rate of a constituent material
of interest entering the module. The time may be measured by a
timing device included in control unit 104.
[0051] Conversely, the same approach can be used to determine the
rate of a constituent material of interest escaping from or exiting
module 108 or 110 or 136, or conduit 138 or 106. In one example, if
the rate of material entering the module 108 is known, under a
specific set of conditions, for example, then the rate of change of
the material levels within module 108 may be used to detect the
escape of loss of material from module 108.
[0052] In one example, the loss or leakage of soot or particles
from a particulate filter module 108 may be detected in this
manner. In this example, operation of the engine at a condition
resulting in a known rate of soot output from the engine and a
known or negligible quantity of soot oxidation on the particulate
filter element 114 may be used to detect failures of filter element
114 resulting in soot leakage. In this example, the rate of change
of soot accumulation on the filter element 114, or the total change
in soot accumulation on the filter element 114 over a specified
time interval may be compared with the known amount of engine-out
soot emissions entering the module 108 during this time period. A
difference in the measured soot accumulation on the filter 114 and
the quantity of soot entering the filter module 108 may indicate
the loss or escape of soot, due to a filter malfunction or failure
such as cracked or melted regions if the increase in measured soot
levels on the filter 114 is less than the quantity of soot entering
module 108. One application of this example is to detect filter
failures for on-board diagnostics. The time interval for the
measurements may be over several seconds or several minutes in one
case. The interval may encompass an entire test cycle, such as a
drive cycle or modal cycle, or only one particular operating
condition. The engine-out soot emissions may be previously
determined, or measured by a sensor such as a PM sensor or radio
frequency sensor.
[0053] The above example need not be limited to particulate
filters, but any type of filter, membrane, or catalyst system,
where a solid, liquid, or gas-phase constituent interacts in a
measureable way with module 108, such as by deposition, adsorption,
reaction with the interaction walls of 108 or certain elements 112
or 114 contained within 108. In this manner, module 108 may serve
as a gas sensor, such as for NOx, CO, HC, O.sub.2, NH.sub.3, or any
other gas, or even a liquid by means of monitoring the change in
one or more radio frequency parameters, according to Equation 1.
The applications include detecting the inflow or outflow of one or
more components from module 108 for control or diagnostic purposes.
In this manner, failures of the catalyst, such as by escape of
certain gas species, may also be determined, or emissions rate of
certain species generated by plant or machine 102 may also be
determined for feedback control.
[0054] The above example need not be always applied to flowing
reactors. When used in batch reactors, conversion rate can be
determined using equation 1, with potential for determining rate of
conversion as a function of both time and location in the reactor
by using different probing modes/frequencies. The obtained
information can be used to control the chemical reactor.
[0055] The measurements described above may also be carried out in
conduit 106, such as by probe 122. Probe 122 may monitor the
material passing through or deposited on the walls of conduit 106.
In one example, probe 122 in conjunction with control unit 104 may
operate as a frequency domain reflectometer or time domain
reflectometer to monitor the location of faults, failures, or
variations in dielectric properties, blockages, obstructions, or
flaws and discontinuities through a portion or all of the
components and systems connected to conduit 106. In this manner,
multiple elements 112, 114, 118, or 116 may be monitored from a
single probe, in one example. In another example, multiple probes
may be used. In particular, the variable probing can involve probe
120 mounted on an SCR, LNT, TWC, hydrocarbon trap, ammonia storage
catalyst or any other catalyst, and probe 122, mounted upstream or
downstream of the module 110.
[0056] In another example, conduit 106 may consist of multiple
branches or legs with various connections, transitions, cavities,
and other elements, such as a conduit network. In one example, the
conduit network is a pipeline or distributed pipe system. Probes
122, 120, 124, or 126 may be used to detect faults within the
conduit network, such as a broken or disconnected conduit, or a
failure of elements within the network such as elements 112, 114,
118, or 116. Failure of an element may result in leakage, such as
leakage of retentate from a filter, leakage of gases, liquids, or
solids, or some other materials. The failure may be detected by a
change in the radio frequency monitored parameter such as an
anomalous feature or discontinuity.
[0057] One distinguishing feature of the system shown in FIG. 1 is
that control unit 104 may be used to monitor and control a network
of probes 120 122, 124, 126, 128, 130, or 132. The network may
consist of at least one probe or any number of probes. In one
example, only one control unit 104 may be used to control and
monitor a large number of probes. Each probe may be used to monitor
a different aspect, parameter, or state, or different component of
the plant, process or engine system shown in FIG. 1. The
measurement can take at different time intervals, and use different
radio frequency characteristics, such as frequency, phase, and/or
amplitude. Measurements from the various probes may be used to
provide direct feedback control of plant or machine 102. In another
example, multiple control units 104 may be used.
[0058] For example control unit 104 may modify engine combustion or
calibration such as fueling, air flow, boost pressure, EGR rates,
injection timing, urea or hydrocarbon dosing and related
parameters, based on radio frequency measurements of properties and
composition of the system inputs. In one application, the blend of
petroleum-based fuel and some other fuel, such as ethanol or
biodiesel may be monitored. In another example, the quality or
composition of urea may be monitored.
[0059] Control unit 104 may also alert the operator or trigger a
fault condition based on radio frequency measurements of fuel
quality, such as high water or sulfur levels. In another example,
control unit 104 may alert the operator or trigger a fault
condition based on radio frequency measurements of the quality,
composition, or level of fuel, oil, coolant, hydraulic fluid,
intake air, urea, ammonia-generating components, or other process
parameters.
[0060] Control unit 104 may further modify engine and exhaust
system operation based on exhaust emissions measurements using
radio frequency probes mounted in conduit 106 or modules 108 or
110. In one embodiment, module 110 may be an SCR catalyst system
and probe 120 may monitor ammonia storage on the SCR catalyst,
using reflection measurements, or transmission with a second probe
in module 110 (transmission) or using probe 122, mounted upstream
or downstream from module 110 or within module 110. Control unit
104 may command urea dosing based on monitored levels of ammonia
storage on SCR catalyst element 116. In another embodiment, probe
126 or probe 122 may monitor the SCR catalyst, among other elements
within the exhaust system. In another example, radio frequency
measurements of ammonia storage on SCR catalyst 116 from probe 120
are used communicate with Engine Control Unit to command engine
lean and rich operation such as to produce ammonia from an upstream
TWC catalyst, so-called passive SCR.
[0061] In another example, module 108 may be a particulate filter
system and measurements from probe 126 or 124 may be used to
control machine 102 operation such as to induce regeneration by
increasing exhaust temperature, hydrocarbon dosing, or any other
means, and also to terminate the regeneration or control the rate
of temperature rise for the regeneration event.
[0062] In one example, element 118 may be an ammonia slip catalyst
or small filter element, and measurements from probe 122 may be
used to detect ammonia slip or particles passing through an
upstream catalyst or filter for diagnostic purposes.
[0063] In another example, probe 122, 130 or any other probe may
monitor the properties of the material such as any gas, liquid, or
solid passing through or contained within conduits 106 or 130 or
modules 136, 108, or 110.
[0064] In another example, only a single probe, such as probe 126
may be used to transmit a radio frequency signal through the entire
exhaust system consisting of conduits 106 and modules 108 and 110
to monitor the processes occurring in each part of the system from
a single probe. In this case, a mesh may be used to contain the
signal at the exit or outlet section of conduit 106 downstream of
module 110. In another example, one or more probes 126 may be used
and one or more meshes or screens may be used.
[0065] In yet another example, in a chemical manufacturing plant,
for example, a Fischer-Tropsch plant, the sensor can monitor the
temperature of the catalyst as well as deposits of waxes or even
the creation of soot on the catalyst. The chemical plant can be a
flowing plant (such as a plug flow reactor) or a batch plant. In
the case of a batch plant, the sensors can monitor conditions such
as conversion of reagents, rate of conversion, pressure and/or
temperature. Information from the control unit 104 can be used to
optimize the performance of the plant.
[0066] In another example, in power plants, solid loading of a
filter unit can be determined by one or more probes in the unit,
and the same unit can be used for monitoring the SCR unit for NOx
control. Particle loading of power plant exhaust units (bag houses
or electrostatic precipitators, for example) can be measured with
spatial resolution by using one probe at different frequency
probing different regions of the filter, or by multiple probes. As
in automotive applications, radio frequency probing of the SCR
unit, the probes can detect ammonia concentration on the catalyst,
and determine proper flow (uniform) of the gases and proper ammonia
distribution through the reactor. It can also determine the level
of activity of the catalyst, indicating potential issues with
sintering or poisoning of the catalyst, indicating the need for
either replacement or regeneration. The measurement in the unit can
indicate issues with maldistribution of the ammonia or the flow
velocities of the gases. Minimization of ammonia slip can be
achieved in a highly controlled system. The same unit can be used
to monitor the temperature of the reactor, to assist in proper
operation of the unit, especially during transients.
[0067] Collectively, the system shown in FIG. 1 forms a radio
frequency-based process control system, whereby multiple components
or sub-systems may be monitored and controlled by one or more
radio-frequency control units 104 in order to optimize operation of
plant or machine 102, or any module 108, 110, or 136 or any other
component or sub-system shown in FIG. 1. The optimization may
include improved efficiency, extended durability, improved
performance or output, or any other desired result, as well as the
alert to any fault conditions or initiation of protective measures
due to a fault condition. The optimization may be achieved by
controlling one or more inputs or processes control variables to
any component or sub-system shown in FIG. 1. The control may be
based on direct feedback control from measurements of each probe,
in order to maintain the measured values within a desired range.
The control may or may not include supplemental model-based
controls or inputs from other sensors or devices.
[0068] In addition to controlling system operation, faults and
malfunctions may also be detected by control unit 104. Such fault
conditions may be detected when a measurement from any of the radio
frequency probes shown in FIG. 1 falls outside of an acceptable
range, or exceeds or falls below a required threshold value. Faults
include excessive emissions, such as particles (soot, ash, or any
other particles) or gas such as regulated emissions, or any other
material. Other system parameters that may be monitored include
parameters required to meet on-board diagnostic requirements.
[0069] Potential failure modes or early signs of failure, as well
as catastrophic failures of any subsystems or components shown in
FIG. 1 may also be monitored. For example, use of a particulate
filter system (module 108) may mask high smoke emissions, such as
due to high fuel consumption, high oil consumption, a coolant leak,
or related malfunction. Control unit 104 and probe 126 or 124 may
be used to detect high smoke, coolant, or water vapor emissions,
which may deposit on filter element 114 or pass through module 108
or conduit 106. Abnormal, such as high levels of ash accumulation
on filter element 114 may also be indicative of high oil
consumption.
[0070] In another example, abnormal emissions (high or low levels)
of different gaseous species, such as NOx or ammonia may also be
detected based on radio frequency measurements of catalysts in
modules 110 or 108. Lubricant and fuel quality and condition may
also be monitored by probe 130 or 128 to diagnose poor quality fuel
or abnormal lubricant aging, or the presence of high soot levels or
wear metal levels for example. Poor combustion may also directly be
detected by probe 132. The loading state of catalyst elements 112,
114,116, as well as catalyst aging, poisoning, or other
characteristics of performance degradation or changes over time may
also be monitored.
[0071] Control unit 104 may also utilize inputs from other sensors
such as temperature sensors, pressure sensors, gas composition
sensors, position sensors, and the like, which are not radio
frequency based, but are not shown in FIG. 1.
[0072] In another embodiment, elements 136, 112, 114, 118, or 116
may be utilized as the sensing elements themselves and monitored by
microwave means using probes 128, 126, 124, 122, or 120. In one
example, filter element 114 is a particulate filter and probe 126
or 124 may rapidly sample the quantity of soot accumulated on the
filter element 114. The derivative of the monitored soot load or
change in soot load over time, provides a direct measure of
engine-out soot emissions. Control unit 104 may provide a feedback
control to machine 102 based on the measured engine-out soot
emissions from filter element 114. In one example, the sample rate
may range from 1 to 10 Hz, but may be faster or slower in some
cases. In the same manner, the instantaneous change in the loading
state of any element 136, 112, 114, 118, or 116 may be monitored
using probes 128, 126, 124, 122, or 120 to provide a real-time or
continuous measurement of the rate of material addition,
accumulation, adsorption, or loss on any of these materials from
the element. In another example, catalyst element 112 is a TWC and
the real-time oxygen concentration may be measured by probe 126 or
probe 124. In another example, catalyst element 116 is an SCR or
LNT and the NOx emissions rate or ammonia dosing rate may be
directly monitored. In yet another example, the concentration of a
material in a conduit, such as conduit 106 may also be
measured.
[0073] FIG. 2 presents additional details of a radio frequency
probe, which may or may not be the same as probes 120 122, 124,
126, 128, 130, or 132 shown in FIG. 1. The probe may be comprised
of a conductive outer sleeve 202, inner dielectric 204, and inner
conductor 206. Alternatively, the probe may be a waveguide of loop
antenna, or any other type of antenna. A perforated conducting
mesh, screen, other housing or sheath 208 may or may not be in
electrical contact with conductive outer sleeve 202. Inner
dielectric may or may not extend fully- or partially over inner
conductor 206 to fully- or partially cover inner conductor 206.
[0074] In one example, sheath 208 may not be used and inner
conductor 206 may extend beyond inner dielectric 204. In another
example, sheath 208 may not be used but inner dielectric 204 may
extend and cover inner conductor 206. In one example, material such
as solids, liquids, or gases may collect or adsorb onto inner
dielectric 204 directly and may be measured. In another example,
sheath 208 may be used, and serves to contain the radio frequency
signal within the region of the sheath. In this manner, the signal
is decoupled or unaffected by the surrounding environment, but is
still exposed to a flow of material which may pass through the
perforations or mesh. In one example, the probe shown in FIG. 2 is
a soot sensor or a gas sensor or a liquid sensor.
[0075] One non-limiting method of control unit operation is
described in the flow chart showing the system control logic in
FIG. 3. Although the figure refers specifically to an exhaust
system, it is intended that the same logic may be applied to any
process control system, including engines, plants, machines, and
the like. A number of inputs from the radio frequency probes shown
in FIG. 1, as well as additional sensors such as temperature,
pressure, flow, composition sensors, and the like are acquired and
monitored by the control unit 104, as shown in Step 60. Sensor
outputs (in the disclosure, the terms "sensor" and "probe" are used
interchangeably) are then utilized by control algorithms contained
on computer readable storage media 140 in the control unit 104, as
shown in Step 62. Furthermore, Step 62 may comprise correcting any
sensor or probe values based on measurements from another sensor or
probe, or stored on within control unit 104. In one example, such
corrections may include correction of the RF signal, or RF
determined signal parameter, based on measurements from a
temperature sensor, or other type of sensor. In another example
multiple RF parameters may be utilized (amplitude, phase,
frequency) or derivatives thereof to determine the final sensor
value. In an exemplary embodiment, both the amplitude and phase
signals may be used. Control unit 104 may further contain a timing
mechanism, to provide time-resolved information.
[0076] Instructions stored in the control unit 104 are used
determine whether any of the sensor values is outside of an
allowable range, or exceeds some threshold value, as shown in Step
64.
[0077] If no sensor values are outside the allowable range, the
control algorithm reverts back to Step 60. If one or more sensor or
probe values is outside the allowable range, the sensor measurement
is verified one or more times, as shown in Step 66. Verification
may be carried out through repeat measurements from the same sensor
or measurements from related or redundant sensors to confirm sensor
performance, or by comparison with additional models, look-up
tables, or stored values. Plausibility checks, such as by
conducting multiple measurements of the same parameter by operating
one or more probes in reflection, transmission or reflection and
transmission mode may be used to verify sensor values. Instructions
stored in the computer readable storage media 140 in the control
unit 104 are used to determine whether the sensor value is truly
outside of an allowable range, or above some threshold value, as
shown in Step 68. If the sensor value is confirmed to be outside
the acceptable range, the computer control unit 104 may save a
number of sensor values and log a fault, as shown in Step 70. The
saved sensor values may or may not be from the same sensor
measuring an abnormal value.
[0078] Additional instructions in the computer readable storage
media 140 in the control unit 104 will then be used to determine
the severity of the malfunction and the actions to be taken, as
shown in Step 72. The control unit 104 may alert the operator to
the malfunction, as shown in Step 74; alter engine, exhaust
aftertreatment operation, or plant, as shown in Step 76; or carry
out some alternate operation, as shown in Step 78.
[0079] It may also be possible to monitor the status of the engine
system or chemical plant by the introduction into the stream of a
compound. The introduced compound can be present under normal
operating conditions of the machine, or it can be one that is
foreign. The introduction of the compound would result in a change
in chemical or physical properties (that results in change in
effective dielectric constant of the catalyst or filter in the
machine); the change in dielectric constant can be monitored using
the microwave system. The introduction of the material can be
switched on and off, allowing the sensing of the microwave response
to changes in the dielectric constant of the machine.
[0080] Those skilled in the art will surely realize that the steps
described above may be carried out in another sequence without
deviating from the intent and scope of the invention.
[0081] While particular embodiments of the invention have been
shown and described, it will be obvious to those skilled in the art
that various changes and modifications may be made without
departing from the present invention in its broader aspects. It is
intended that all matter contained in the above description and
shown in the accompanying drawings shall be interpreted as
illustrative and not in a limiting sense.
* * * * *