U.S. patent application number 11/726313 was filed with the patent office on 2007-07-26 for particulate loading monitoring system.
Invention is credited to Andrew A. Knitt.
Application Number | 20070169469 11/726313 |
Document ID | / |
Family ID | 39263077 |
Filed Date | 2007-07-26 |
United States Patent
Application |
20070169469 |
Kind Code |
A1 |
Knitt; Andrew A. |
July 26, 2007 |
Particulate loading monitoring system
Abstract
A particulate trap regeneration system is provided, which may
include a particulate trap having a filter medium configured to
remove one or more types of particulate matter from an exhaust flow
of an engine and a regeneration device configured to reduce an
amount of particulate matter in the particulate trap, as well as a
radio frequency-based particulate loading monitoring system
configured to determine an amount of particulate matter trapped by
the filter medium. The particulate loading monitoring system may be
powered by an energy-harvesting device. The particulate loading
monitoring system may include at least one radio frequency probe
configured to transmit radio frequency signals of predetermined
magnitude and predetermined frequency toward the filter medium and
at least one radio frequency probe configured to receive and
measure the magnitude of received radio frequency signals that pass
through the filter medium. Further, the system may be configured to
transmit radio frequency signals along a length of the exhaust
conduit.
Inventors: |
Knitt; Andrew A.; (Deer
Creek, IL) |
Correspondence
Address: |
Caterpillar Inc.;Intellectual Property Dept.
AB 6490
100 N.E. Adams Street
PEORIA
IL
61629-6490
US
|
Family ID: |
39263077 |
Appl. No.: |
11/726313 |
Filed: |
March 21, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11644540 |
Dec 21, 2006 |
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11726313 |
Mar 21, 2007 |
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11393681 |
Mar 31, 2006 |
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11644540 |
Dec 21, 2006 |
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11189530 |
Jul 26, 2005 |
7157919 |
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11393681 |
Mar 31, 2006 |
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Current U.S.
Class: |
60/295 ;
60/297 |
Current CPC
Class: |
F01N 2560/14 20130101;
F02D 2200/0812 20130101; F01N 2560/00 20130101; F01N 2560/08
20130101; F01N 2560/06 20130101; Y02T 10/47 20130101; Y02T 10/40
20130101; F01N 3/025 20130101; F01N 11/00 20130101; F02D 41/28
20130101; F01N 9/002 20130101; F01N 3/021 20130101 |
Class at
Publication: |
060/295 ;
060/297 |
International
Class: |
F01N 3/00 20060101
F01N003/00 |
Claims
1. A particulate loading monitoring system for a filter medium
located within a particulate trap, the particulate trap located in
an exhaust conduit, comprising: a first probe configured to
transmit radio frequency signals toward a filter medium; a second
probe configured to receive radio frequency signals that pass
through the filter medium; and an energy-harvesting device
configured to provide power to at least one of the first and second
probes.
2. The particulate loading monitoring system of claim 1, further
comprising: a controller configured to determine, based on the
received radio frequency signals, a particulate loading value
indicative of the amount of particulate matter trapped in the
filter medium
3. The particulate loading monitoring system of claim 2, wherein
the energy-harvesting device is configured to provide power to the
controller.
4. The particulate loading monitoring system of claim 1, further
comprising: at least one sensor configured to take at least one of
pressure and temperature readings, the energy-harvesting device
configured to provide power to the at least one sensor.
5. The particulate loading monitoring system of claim 1, wherein
the first probe is configured transmit radio frequency signals
along the exhaust conduit external to the particulate trap.
6. The particulate loading monitoring system of claim 5, further
comprising: a third probe located upstream of the particulate trap,
the third probe configured to receive radio frequency signals
propagated along the exhaust conduit.
7. The particulate loading monitoring system of claim 1, wherein
the first probe is located within the particulate trap and the
second probe is located upstream of the particulate trap.
8. The particulate loading monitoring system of claim 1, wherein
the first probe is located downstream of the filter medium and the
second probe is located upstream of the particulate trap.
9. The particulate loading monitoring system of claim 1, wherein
the energy-harvesting device is thermoelectric.
10. A method of determining particulate loading of a filter medium
inside a particulate trap, the particulate trap located in an
exhaust conduit, comprising: generating power using a
energy-harvesting device; supplying generated power to a
particulate loading monitoring system; and determining particulate
loading by: transmitting radio frequency signals toward a filter
medium; receiving the radio frequency signals that pass through the
filter medium; and determining, based on the received radio
frequency signals, a particulate loading value indicative of an
amount of particulate matter trapped in the filter medium.
11. The method of claim 10, wherein power is generated using a
thermoelectric energy-harvesting device.
12. The method of claim 10, further including: collecting
information from at least one sensor; and determining the
particulate loading value based on the received radio frequency
signals and the collected information.
13. The method of claim 10, wherein determining particulate loading
further includes: transmitting radio frequency signals within the
exhaust conduit external to the particulate trap; and receiving
radio frequency signals upstream the exhaust conduit from the
particulate trap.
14. The method of claim 10, further including: determining if more
than a predetermined amount of particulate matter is trapped in the
filter medium; and activating a regenerating device, the
regenerating device configured to reduce an amount of particulate
matter in the filter medium, if the value exceeds the predetermined
amount of particulate matter.
Description
RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 11/644,540, filed Dec. 21, 2006, which is a
continuation-in-part of U.S. patent application Ser. No.
11/393,681, filed Mar. 31, 2006, which is a continuation-in-part of
U.S. patent application Ser. No. 11/189,530, filed Jul. 26,
2005.
TECHNICAL FIELD
[0002] The present disclosure is directed to a particulate trap
regeneration system and, more particularly, to a particulate trap
regeneration system having a particulate loading monitoring
system.
BACKGROUND
[0003] Engines, including diesel engines, gasoline engines, natural
gas engines, and other engines known in the art, may exhaust a
complex mixture of air pollutants. The air pollutants may be
composed of both gaseous and solid material, such as, for example,
particulate matter. Particulate matter may include ash and unburned
carbon particles and may sometimes be referred to as soot.
[0004] Due to increased environmental concerns, exhaust emission
standards have become more stringent. The amount of particulate
matter and gaseous pollutants emitted from an engine may be
regulated depending on the type, size, and/or class of engine. In
order to meet these emissions standards, engine manufacturers have
pursued improvements in several different engine technologies, such
as fuel injection, engine management, and air induction, to name a
few. In addition, engine manufacturers have developed devices for
treatment of engine exhaust after it leaves the engine.
[0005] Engine manufacturers have employed exhaust treatment devices
called particulate traps to remove the particulate matter from the
exhaust flow of an engine. A particulate trap may include a filter
designed to trap particulate matter. The use of the particulate
trap for extended periods of time, however, may enable particulate
matter to accumulate on the filter, thereby causing damage to the
filter and/or a decline in engine performance.
[0006] One method of restoring the performance of a particulate
trap may include regeneration. Regeneration of a particulate trap
filter system may be accomplished by thermal regeneration, which
may include increasing the temperature of the filter and the
trapped particulate matter above the combustion temperature of the
particulate matter, thereby burning away the collected particulate
matter and regenerating the filter system. This increase in
temperature may be effectuated by various means. For example, some
systems employ a heating element (e.g., an electric heating
element) to directly heat one or more portions of the particulate
trap (e.g., the filter material or the external housing). Other
systems have been configured to heat the exhaust gases upstream
from the particulate trap, allowing the flow of the heated gases
through the particulate trap to transfer heat to the particulate
trap. For example, some systems may alter one or more engine
operating parameters, such as air/fuel mixture, to produce exhaust
gases with an elevated temperature. Running an engine with a "rich"
air/fuel mixture can elevate exhaust gas temperature. Other systems
heat the exhaust gases upstream from the particulate trap, with the
use of a burner that creates a flame within the exhaust conduit
leading to the particulate trap.
[0007] In some systems, regeneration may be performed continually.
In other systems, regeneration may be performed periodically. That
is, after a trigger condition occurs, a thermal regeneration system
may initiate regeneration in response to the trigger condition.
Some systems are configured to initiate regeneration in response to
a single type of trigger condition, such as the operation of the
engine for a predetermined amount of time or a pressure
characteristic of the exhaust system (e.g., backpressure in the
exhaust system). Some systems are configured to initiate
regeneration in response to measurements of the amount of
particulate matter accumulated in the particulate trap. For
example, one such regeneration system is disclosed by U.S. Pat. No.
4,477,771 issued to Nagy et al. on Oct. 16, 1984 ("the '771
patent"). The '771 patent discloses a regeneration system
configured to initiate regeneration in response to a determination
of power loss of microwaves transmitted through the filter medium
within a particulate trap.
[0008] The system of the '771 patent may be configured to initiate
regeneration in response to a determination of power loss of a
radio frequency (RF) signal. However, the system of the '771 patent
utilizes microwaves rather than low frequency RF signals. For
example, the '771 patent discloses use of RF signals having
frequencies on the order of 1.85 GHz (1850 MHz). Use of higher
frequencies, such as the microwaves used in the '771 patent,
requires system components that are more complicated and thus cost
more at each stage of development and production. Further, the use
of microwaves, as in the '771 patent, often requires a waveguide or
resonant chamber. The requirement of such a chamber may limit the
design possibilities of a particulate trap housing.
[0009] Furthermore, most particulate loading monitoring systems
monitor by using a number of sensors, such as temperature and
pressure sensors. These sensors require electrical power to
operate, and their signals must be transmitted to an electronic
controller for the monitoring system. This is generally performed
using a wiring harness. The wiring harness is generally routed from
the engine to the particulate trap and must be capable of enduring
high temperatures.
[0010] The present disclosure is directed to solving one or more of
the problems described above.
SUMMARY OF THE INVENTION
[0011] In one aspect, the present disclosure is directed to a
particulate loading monitoring system for a filter medium inside a
particulate trap. The particulate trap may be located in an exhaust
conduit. The system may comprise a first probe configured to
transmit a radio frequency signals toward a filter medium and a
second probe configured to receive radio frequency signals that
pass through the filter medium. The system may also comprise an
energy-harvesting harvesting device configured to provide power to
at least one of the first and second probes.
[0012] In another aspect, the present disclosure is directed to a
method of determining particulate loading of a filter medium inside
a particulate trap. The particulate trap may be located in an
exhaust conduit. The method may include generating power using a
energy-harvesting device, supplying generated power to a
particulate loading monitoring system, and determining particulate
loading. Particulate loading may be determined by transmitting
radio frequency signals toward a filter medium, receiving the radio
frequency signals that pass through the filter medium, and
determining, based on the received radio frequency signals, a
particulate loading value indicative of an amount of particulate
matter trapped in the filter medium.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] The accompanying drawings, which are incorporated in and
constitute a part of this specification, illustrate several
exemplary embodiments of the invention and, together with the
description, serve to explain the principles of the invention. In
the drawings,
[0014] FIG. 1 is a diagrammatic illustration of a machine according
to an exemplary disclosed embodiment;
[0015] FIG. 2a is a diagrammatic illustration of a particulate trap
regeneration system according to an exemplary disclosed
embodiment;
[0016] FIG. 2b is a diagrammatic illustration of a particulate trap
regeneration system according to a second exemplary disclosed
embodiment;
[0017] FIG. 2c is a diagrammatic illustration of a particulate trap
regeneration system according to a third exemplary disclosed
embodiment;
[0018] FIG. 2d is a diagrammatic illustration of a particulate trap
regeneration system according to a fourth exemplary disclosed
embodiment;
[0019] FIG. 3 is a schematic of a particulate loading monitoring
system according to an exemplary disclosed embodiment; and
[0020] FIG. 4 is a schematic of a narrowband particulate loading
monitoring system according to an exemplary disclosed
embodiment.
DETAILED DESCRIPTION
[0021] Reference will now be made in detail to embodiments of the
invention, examples of which are illustrated in the accompanying
drawings. Whenever possible, the same reference numbers will be
used throughout the drawings to refer to the same or like
parts.
[0022] FIG. 1 illustrates a machine 10. Machine 10 may include an
operator station 11, one or more traction devices 12, a frame 13,
an engine 14, which may be mounted to frame 13, and a particulate
trap regeneration system 16.
[0023] Although machine 10 is shown as a truck, machine 10 could be
any type of machine having an exhaust producing engine.
Accordingly, traction devices 12 may be any type of traction
devices, such as, for example, wheels, as shown in FIG. 1, tracks,
belts, or any combinations thereof.
[0024] Engine 14 may be any kind of engine that produces an exhaust
flow of exhaust gases. For example, engine 14 may be an internal
combustion engine, such as a gasoline engine, a diesel engine, a
gaseous fuel burning engine or any other exhaust gas producing
engine.
[0025] System 16 may include an after-treatment device 18.
After-treatment device 18 may be any type of device configured to
remove one or more constituents from the exhaust flow of engine 14.
In some embodiments, after-treatment device 18 may be regenerated
by heat or some other measure. In one embodiment, after-treatment
device 18 may include a particulate trap 19. Particulate trap 19
may be configured to remove one or more types of particulate matter
from the exhaust gases produced by engine 14 and flowing through an
exhaust conduit 20 configured to direct all or a portion of the
exhaust gases produced by engine 14 to after-treatment device 18.
Particulate trap 19 may include an outer housing 22, which may
encase a filter medium 24 (e.g. a metal mesh or screen, or a porous
ceramic material, such as cordierite) configured to remove (i.e.,
trap) one or more types of particulate matter from the exhaust flow
of engine 14. Although after-treatment device 18 is discussed
herein primarily as being a particulate trap, in other embodiments,
after-treatment device 18 may include multifunctional devices such
as a combination of a catalytic converter and a particulate trap in
the same unit or a catalytic particulate trap, wherein filter
medium 24 may include a catalytic material and/or a catalytic
coating.
[0026] After-treatment device 18 may be configured to be thermally
regenerated. That is, regeneration of after-treatment device 18 may
be accomplished by increasing the temperature of after-treatment
device 18. Such increases in temperature of after-treatment device
18 may be generated in a number of different ways. For example,
heat may be directly applied to after-treatment device 18 via a
heating device integral with or adjacent to after-treatment device
18. An example of such a heating device may include an electric
heating element (not shown).
[0027] Alternatively or additionally, the temperature of
after-treatment device 18 may be increased by heat transferred to
it from the exhaust gases flowing through it. In such embodiments,
heat may be applied to exhaust gases upstream from after-treatment
device 18. The temperature of the exhaust gases may be increased in
one or more ways. For example, altering engine parameters may have
an effect on exhaust gas temperature. Running engine 14 with a
"rich" air/fuel mixture may increase exhaust gas temperature.
Increases in engine load may also increase exhaust gas temperature.
Exhaust gases may also be heated by post injection, which involves
injecting additional fuel into the combustion chambers after the
combustion has taken place, which may result in the additional fuel
being burned in the exhaust system, thereby elevating the
temperature of the exhaust gases in the system.
[0028] Exhaust temperature may also be raised by heating the
exhaust gases or exhaust conduit 20. For example, an electric
heating element and/or flame producing burner may be configured to
heat the exhaust gases or exhaust conduit 20. In one embodiment,
system 16 may include a regeneration device 25 configured to reduce
an amount of particulate matter in after-treatment device 18. For
example, regeneration device 25 may include a burner assembly 26
configured to increase the temperature of the exhaust gases flowing
through exhaust conduit 20 upstream from after-treatment device 18.
Burner assembly 26 may be configured to maintain or restore the
performance of after-treatment device 18 through thermal
regeneration. Accumulation of exhaust flow constituents in
after-treatment device 18 may result in a decline in engine
performance and/or possible damage to after-treatment device 18
and/or other components of system 16.
[0029] Burner assembly 26 may be configured to prevent or restore
any decline in engine performance and avoid possible damage to
after-treatment device 18 and/or other components of system 16. For
example, burner assembly 26 may be configured to cause at least
some of the particulate matter that may have accumulated in
after-treatment device 18 to be burned off.
[0030] Although system 16 is shown with a single after-treatment
device 18 and a single regeneration device 25, system 16 may
include more than one after-treatment device 18 and/or more than
one regeneration device 25. For example, in one embodiment, system
16 may include a single regeneration device 25 configured to
regenerate two after-treatment devices. In another embodiment,
system 16 may include two regeneration devices configured to
regenerate two after-treatment devices. In such an embodiment, each
regeneration device may be configured to regenerate one of the
after-treatment devices or contribute to the regeneration of both
of the after-treatment devices. System 16 could also include any
number of regeneration devices and/or after-treatment devices in
any combination suitable for regeneration.
[0031] FIG. 2a illustrates an exemplary embodiment of particulate
trap regeneration system 16. For purposes of the following
explanation, after-treatment device 18 will be discussed as being
particulate trap 19, while regeneration device 25 will be discussed
as being burner assembly 26. However, it should be noted that
after-treatment device 18 and regeneration device 25 could be any
of the disclosed types of after-treatment and regeneration devices
mentioned above. System 16 may also include a controller 28
configured to receive information from various sources and control
one or more components of system 16 based on this information.
[0032] Burner assembly 26 may be positioned anywhere along exhaust
conduit 20 between engine 14 and particulate trap 19. Burner
assembly 26 may include a fuel injector 30 configured to supply
fuel to burner assembly 26. Burner assembly 26 may be configured to
create a flame, which may be in a heat exchange relationship with
the exhaust flow. System 16 may be configured to supply fuel
injector 30 with fresh air for mixing with the fuel for combustion,
as well as for flushing fuel injector 30 of any fuel or debris
before and/or after operation of burner assembly 26. The supply of
air to fuel injector 30 may be regulated by an air valve 31,
controllable by controller 28.
[0033] In some embodiments, the source of the fresh air may be an
air intake system 32 of engine 14. That is, air may be routed from
a portion of air intake system 32, such as an intake manifold 34,
downstream from a compressor 36 configured to create forced
induction for engine 14. Compressor 36 may include a turbocharger,
supercharger, or any other device configured to compress intake air
and thereby produce forced induction for engine 14. Air may be
directed from intake manifold 34 to fuel injector 30 via an air
conduit 38. The supply of air to fuel injector 30 may be regulated
by air valve 31, which may be controllable by controller 28 as
discussed above.
[0034] Burner assembly 26 may also include a spark plug 40
configured to provide spark to ignite the air/fuel mixture
delivered by fuel injector 30. Current may be supplied to spark
plug 40 by an ignition coil 42, which may be controllable by
controller 28. Although burner assembly 26 has been shown and
described as including spark plug 40, alternative ignition sources
may be employed, such as, for example, glow plugs or any other
means for igniting an air/fuel mixture.
[0035] System 16 may also include a radio frequency-based
particulate loading monitoring system 44 configured to determine an
amount of particulate matter trapped by filter medium 24. Each
component of particulate loading monitoring system 44 may be
located or configured to be located on board machine 10.
[0036] Particulate loading monitoring system 44 may include a radio
frequency synthesizer 46 configured to deliver radio frequency
signals to a radio frequency transmitting probe 48, which may be
configured to transmit the radio frequency signals to thereby
introduce them to filter medium 24. Particulate loading monitoring
system 44 may also include a radio frequency receiving probe 50
configured to receive radio frequency signals that pass through
filter medium 24.
[0037] Radio frequency transmitting probe 48 and receiving probe 50
may be any of a number of shapes and sizes and may be situated in
and/or around filter medium 24 in various ways. The shape and
configuration of transmitting probe 48, receiving probe 50,
after-treatment device 18, and filter medium 24 may influence the
transmission of radio frequency signals through filter medium 24,
as well as detection of such transmission. As such, these
components may be designed to optimize transmission and reception
of a selected frequency or frequency range within one or more
filter system geometries. Additionally, radio frequency
transmitting probe 48 and receiving probe 50 may be configured to
transmit and receive radio frequency signals.
[0038] Particulate loading monitoring system 44 may be further
configured to detect magnitudes of radio frequency signals
reflected by radio frequency transmitting probe 48 and determine
the amount of particulate matter trapped by the filter medium 24
based on the detected magnitudes of radio frequency signals
reflected by transmitting probe 48. As more particulate matter
accumulates on filter medium 24, the permittivity of filter medium
24 changes. Due to this change in permittivity, the magnitude of RF
signal reflected by transmitting probe 48 changes. Therefore, in a
calibrated system, detected, reflected RF signals can be used to
determine the amount of particulate matter accumulated on filter
medium 24. A measurement of reflected RF signal may be used by
itself or in conjunction with a measurement of signal loss across
filter medium 24 to determine the amount of particulate matter
accumulated in filter medium 24.
[0039] In some embodiments, particulate loading monitoring system
44 may be configured to transmit a frequency swept signal, i.e.,
signals of varying frequency within a predetermined band of
frequencies. For example, particulate loading monitoring system 44
may be configured to transmit signals of a predetermined magnitude
and having frequencies less than about 500 MHz. In certain
embodiments, the frequency swept signal may include a band of
frequencies between about 100-400 MHz.
[0040] Particulate loading monitoring system 44 may be configured
to determine RF signal loss across filter medium 24. That is,
particulate loading monitoring system 44 may be configured to
measure the magnitude of the received radio frequency signals that
pass through filter medium 24 and compare the measured magnitude of
the received signals of one or more frequencies to the magnitude of
the transmitted signals of the same one or more frequencies. For
example, particulate loading monitoring system 44 may be configured
to compare the magnitude of signal of each frequency transmitted to
the magnitude of signal of the same frequency that is received. The
difference between these two magnitudes is the signal loss at that
frequency, the value of which may be measured in dB or dBm.
Particulate loading monitoring system 44 may be configured to make
this determination for each frequency at which a signal is
transmitted by transmitting probe 48.
[0041] Particulate loading monitoring system 44 may also be
configured to wirelessly communicate sensor data from the system 44
to an electronic controller 15 that may be located on or near the
engine 14. FIG. 2b is a diagrammatic illustration of a particulate
trap regeneration system 16 according to a second exemplary
disclosed embodiment. Similar to FIG. 2a, radio frequency
transmitting probe 48 may be configured to transmit radio frequency
signals and radio frequency receiving probe 50 may be configured to
receive radio frequency signals that pass through the filter medium
24. The controller 28 may be configured to receive the measured
radio frequency signals and any other data from sensors 52, 54, 56,
58, such as temperature and pressure data. The controller 28 may
then take any processed or unprocessed data and cause the
transmitting probe 48 to transmit a second radio frequency signal,
using the exhaust conduit 20 as a wave guide, to a second receiving
probe 50 connected to the engine controller 15. Alternatively, the
system 44 may be configured with the transmitting probe 48
downstream of the filter medium 24 to transmit a radio frequency
signal across the filter medium 24 and along the exhaust conduit to
be received by a receiving probe 50 near the engine 14. The
receiving probe 50 near the engine 14 may be connected to the
engine controller 15. The radio frequency signal may transmit any
processed 6r unprocessed data and may indicate particulate loading
in the filter medium 24. It is also contemplated that the data from
the system 44 may be sent wirelessly to a remote location using
radio frequencies external to the exhaust conduit 20 rather than
using the exhaust conduit 20 as a waveguide.
[0042] FIG. 2c is a diagrammatic illustration of a particulate trap
regeneration system according to a third exemplary disclosed
embodiment. This embodiment is similar to the discussion of FIG.
2b, except that an energy-harvesting device 27 is shown as a part
of the particulate loading management system 44. The
energy-harvesting device 27 may be provided to supply electrical
power devices, such as the probe 48, sensors 52,54,56,58, radio
frequency synthesizer 46, controller 28 and the like. The
energy-harvesting device 27 may be any device capable of harvesting
energy from the machine or vehicle such that the particulate
loading management system 44 doesn't have to be wired for power
from the machine 10. Although a controller 28 is shown as part of
the system 44, the controller may be replaced by a wireless data
radio (not shown) or the like to facilitate the control of radio
frequency transmissions or to cause the radio frequency
transmissions.
[0043] The energy-harvesting device 27 may utilize one of a number
of methods to generate electricity, such as thermoelectric power
generation from exhaust waste heat, piezoelectric power generation
from vibrations, electromechanical power generation from created
electromechanical fields, and the like. It may also be necessary to
add a converter (not shown) to the system 44 to convert the voltage
provided by the energy-harvesting device 27 to a voltage that is
useable by the probe 48, sensors 52,54,56,58, controller 28 and the
like. Although the energy-harvesting device 27 is shown applied to
this embodiment, it is contemplated that the energy-harvesting
device 27 could be used in any number of configurations to provide
power to at least parts of the particulate loading management
system 44.
[0044] FIG. 2d is a diagrammatic illustration of a particulate trap
regeneration system according to a fourth exemplary disclosed
embodiment. In this embodiment, the pressure and temperature
sensors 52,54,56,58 and receiving probe 50 may be passive radio
frequency sensors and probes using passive radio frequency
technology rather than active sensors and probes powered using
machine power or power generated from energy harvesting devices 27
such as those discussed above. A radio frequency reader 47 may be
connected to the engine controller 15. Upon receiving a request
from the controller to take a reading of the sensors 52,54,56,58
and/or probe 50, the radio frequency reader 47 may emit a radio
frequency signal that may travel along the exhaust conduit 20. As
the signal reaches each sensor 52,54,56,58 and/or probe 50, each
sensor 52,54,56,58 and/or probe 50 may use energy from the signal
to power up, thereby taking a measurement and then transmitting a
signal back to or readable by the radio frequency reader 47 using
the exhaust conduit 20 as a waveguide. Furthermore, the radio
frequency signal from the radio frequency reader 47 may also be
transmitted through the filter medium 24. This signal or a return
signal may be used to measure the attenuation of the magnitude of
the signal across the filter medium 24 to determine the amount of
particulate that has accumulated in the filter medium 24.
[0045] In embodiments of the present disclosure sending data
wirelessly along the exhaust conduit 20, various measures may be
taken to prevent radio frequency signals from propagating along the
entire length of the exhaust conduit 20 to an outlet of the exhaust
conduit 20. These measures may include steps such as adding a mesh
like grate to the opening on the exhaust conduit outlet end of the
particulate trap 19, and the like. These measures may allow for
higher radio frequency signal power levels.
[0046] The controller 28 may be configured to determine the amount
of particulate loading in particulate trap 19 based on the signal
loss value. Alternatively or additionally, controller 28 may be
calibrated to convert the measured magnitude of received and/or
reflected radio frequency signals directly to a particulate loading
value.
[0047] Controller 28 may include any means for receiving machine
operating parameter-related information and/or for monitoring,
recording, storing, indexing, processing, and/or communicating such
information. These means may include components such as, for
example, a memory, one or more data storage devices, a central
processing unit, or any other components that may be used to run an
application.
[0048] Although aspects of the present disclosure may be described
generally as being stored in memory, one skilled in the art will
appreciate that these aspects can be stored on or read from types
of computer program products or computer-readable media, such as
computer chips and secondary storage devices, including hard disks,
floppy disks, optical media, CD-ROM, or other forms of RAM or ROM.
Various other known circuits may be associated with controller 28,
such as power supply circuitry, signal-conditioning circuitry,
solenoid driver circuitry, communication circuitry, and other
appropriate circuitry.
[0049] Controller 28 may perform multiple processing and
controlling functions, such as, for example, engine management
(e.g., controller 28 may include an engine controller 15, a.k.a. an
engine control module or ECM), monitoring of particulate loading,
and controlling regeneration of particulate trap 19. Alternatively,
machine 10 may include multiple controllers, each dedicated to
perform one or more of these or other functions. Such multiple
controllers may be configured to communicate with one another. For
example, particulate loading monitoring system 44 may include a
first controller/processor 28, which may be configured to determine
the amount of particulate matter accumulated in filter medium 24
based on the signals transmitted by transmitting probe 48 and those
detected by receiving probe 50, as well as detected power reflected
by transmitting probe 48. Such a dedicated controller 28 may also
be configured to forward this determination of particulate
accumulation to a second controller/processor, such as the engine
controller 15, which may be configured to control regeneration in
response to such information from the first controller 28.
Alternatively, the operation of the controller 28, described
herein, may be performed as a part of the operation of the engine
controller 15, such that the engine controller 15 may process any
signals and data from any sensors 52,54,56,58 and/or probes 48,50
and control regeneration.
[0050] Controller 28 may be configured to receive the signals
detected by receiving probe 50 or information about such signals.
Controller 28 may be further configured to activate regeneration
device 25 in response to particulate loading monitoring system 44
detecting more than a predetermined amount of particulate matter
trapped in filter medium 24.
[0051] Controller 28 may also be configured to activate
regeneration device 25 in response to one or more other trigger
conditions. These other trigger conditions may include, for
example, operation of engine 14 for a predetermined amount of time;
consumption of a predetermined amount of fuel by engine 14;
detection of an elevated backpressure upstream of particulate trap
19 above a predetermined pressure; detection of a pressure
differential across particulate trap 19 of greater than a
predetermined amount; and a determination that a calculated amount
of particulate matter accumulated in particulate trap 19 is above a
predetermined amount.
[0052] Regeneration may also be initiated manually by an operator,
owner, service technician, etc. of machine 10. Manually triggering
regeneration may be accomplished via a switch, button, or the like
associated with machine 10 and/or a service tool configured to
interface with machine 10.
[0053] System 16 may include various sensors configured to generate
information about operating parameters of system 16. Such
information may be received by controller 28. For example, system
16 may include an upstream temperature sensor 52, an upstream
pressure sensor 54, a downstream temperature sensor 56, and a
downstream pressure sensor 58. Such sensors may be positioned along
exhaust conduit 20 upstream and downstream from particulate trap 19
respectively and configured to take measurements of the temperature
and pressure of the exhaust gases within exhaust conduit 20 at
their respective locations.
[0054] Upstream pressure sensor 54 and downstream pressure sensor
58 may constitute a pressure differential measurement system. Such
a system may be configured to measure a pressure differential
between an upstream pressure of the exhaust flow upstream from
particulate trap 19 and a downstream pressure of the exhaust flow
downstream from particulate trap 19. Alternatively, in lieu of
upstream pressure sensor 54 and downstream pressure sensor 58, the
pressure differential measurement system may include a single
pressure differential sensor (not shown) configured to measure the
difference in pressure between the exhaust flow upstream and
downstream of particulate trap 19.
[0055] System 16 may also include a ground speed sensor 60
configured to monitor the ground speed of machine 10 (i.e., the
speed of machine 10 relative to the surface over which it travels).
System 16 may also be provided with a flame sensing system
associated with burner assembly 26 and configured to detect whether
burner assembly 26 is currently producing a flame. Such a flame
sensing system may include, for example, a flame sensor 62. In
addition, system 16 may include an engine speed sensor 64
configured to measure the speed at which engine 14 is operating
(i.e., rpm).
[0056] The aforementioned sensors may include any type of sensing
means suitable for monitoring their respective parameters. In
particular, flame sensor 62 may include any type of sensor suitable
for detecting the presence of a flame, such as temperature sensors
(e.g., thermocouples), optical sensors, ultraviolet sensors, and
ion sensors. Flame sensor 62 may be configured to detect a
condition (e.g., temperature, ultraviolet light, ions, etc.) in
proximity to the flame. Such a condition may be monitored at any
location within close enough proximity to the flame to enable the
presence of the flame to be detected. Additionally or
alternatively, the flame sensing system may be configured to detect
a rate of change in the condition. For example, a temperature in
proximity to the flame location that is increasing at a
predetermined rate may indicate that a flame is lit and causing the
increase
[0057] In addition or as an alternative to flame sensor 62,
upstream temperature sensor 52 may be located upstream of burner
assembly 26. In such an embodiment the flame sensing system may be
configured to determine whether the downstream exhaust temperature
measured by downstream temperature sensor 56 exceeds the upstream
exhaust temperature measured by upstream temperature sensor 52 by a
predetermined amount. A significantly higher downstream temperature
may indicate that the flame is lit and is thus heating exhaust
gases as they flow through burner assembly 26.
[0058] In some embodiments, upstream temperature sensor 52 or any
other temperature sensing device may be configured to take a
temperature measurement indicative of a temperature of particulate
trap 19. Such temperature measurements may be taken in a manner
suitable for determining the temperature of particulate trap 19 at
the time the radio signals are received by receiving probe 50.
Controller 28 may be configured to determine, based on the measured
magnitude of radio frequency signals received by receiving probe
50, a particulate loading value indicative of the amount of
particulate matter trapped in filter medium 24. Controller 28 may
also be configured to perform a temperature compensation, which may
include modifying, based on the temperature measurement, at least
one of the following: the measured magnitude of the received radio
frequency signals that pass through the filter medium or the
particulate loading value. In embodiments configured to determine a
signal loss value, the signal loss value may be modified to
facilitate the temperature compensation.
[0059] The temperature compensation may involve a function that is
based on the temperature measurement and at least one of the
following: the measured magnitude of the received radio frequency
signals that pass through filter medium 24 or the particulate
loading value. In some embodiments the function may be based on a
signal loss value. Further, in some embodiments, the function may
be a third order polynomial. That is, the determination of actual
particulate loading may be a function of the temperature
measurement and observed particulate loading, which may be
represented by the measured magnitude of the received radio
frequency signals that pass through filter medium 24, the signal
loss value, and/or the particulate loading value. Alternatively,
the temperature compensation may involve a look-up table based on
the temperature measurement and observed particulate loading, as
represented by the aforementioned values.
[0060] Controller 28 may include a timing device 66. Controller 28
may be configured to couple information from timing device 66 with
information from other sources. For example, controller 28 may
utilize information from timing device 66 in conjunction with
information regarding operation of engine 14 (e.g., from engine
speed sensor 64 to determine how long engine 14 is operated. Timing
device 66 may also be used to monitor and control duration of
regeneration events or any other operating parameters of system 16
and/or machine 10.
[0061] System 16 may be configured to control one or more
additional system functions and/or parameters. Controller 28 may be
configured to control the pressure of the fuel delivered to fuel
injector 30 (and therefore the rate of fuel injection). A fuel
on/off valve 68, which may be controllable by controller 28, may be
associated with fuel injector 30 to selectively allow fuel to be
delivered to fuel injector 30. In addition to fuel on/off valve 68,
system 16 may also include a fuel pressure regulator valve 70
controllable by controller 28 to regulate the pressure of the fuel,
and thereby the rate at which fuel is delivered to fuel injector
30. In some embodiments, controller 28 may be configured to control
the pressure of fuel delivered to fuel injector 30 in a closed loop
fashion, i.e., in response to pressure measurements taken at or
near fuel injector 30 (e.g., by a fuel pressure sensor, not
shown).
[0062] Controller 28 may be further configured to control fuel
on/off valve 68 and/or fuel pressure regulator valve 70 (i.e., flow
of fuel to fuel injector 30) in response to other parameters of
system 16. For example, controller 28 may be configured to control
the temperature of exhaust gases entering particulate trap 19 in
response to feedback from upstream temperature sensor 52. This
upstream exhaust temperature may be controlled by regulating the
amount of fuel and/or air supplied to fuel injector 30, which may
be accomplished by controlling fuel on/off valve 68 and/or fuel
pressure regulator valve 70. Other types of regeneration devices or
methods may be controlled in response to measurements taken by
upstream temperature sensor 52. For example, the amount of post
injection may be varied (e.g., by controller 28) to control the
temperature of the exhaust gases entering any kind of
after-treatment device 18.
[0063] System 16 may include multiple fuel pressure regulator
valves, which may be independently controlled. At least one fuel
pressure regulator valve 70 may be configured to regulate main fuel
pressure, and a second fuel pressure regulator valve (not shown)
may be configured to regulate pilot fuel pressure. Pilot fuel
pressure may be used during a pilot mode in which system 16
utilizes a predetermined air/fuel mixture to prevent flameouts
during various engine operating conditions, e.g., hard
accelerations and rapid decelerations.
[0064] Other operating parameters of system 16 may be monitored to
maintain and/or optimize control of the regeneration process. For
example, downstream temperature sensor 56 may detect whether
downstream exhaust temperature is above a predetermined
temperature. If downstream exhaust temperatures get too high, it
could be an indication that temperatures within particulate trap 19
may be at an undesirably high level as well and/or that the
regeneration may be somewhat unstable (e.g., incineration of
particulate matter and/or a catalyst driven reaction may be
intensifying within after-treatment device 18 beyond a level
commanded by controller 28).
[0065] System 16 may also be configured to monitor the stability of
the regeneration process by determining a difference between the
upstream exhaust temperature measured by upstream temperature
sensor 52 and the downstream exhaust temperature measured by
downstream temperature sensor 56. If the temperature measured by
downstream temperature sensor 56 exceeds that measured by upstream
temperature sensor 52 by more than a predetermined amount for more
than a predetermined amount of time, controller 28 may initiate
steps to scale back or terminate the regeneration process. For
example, in such a case, controller 28 may reduce the intensity of
the flame produced by burner assembly 26. In some circumstances,
controller 28 may terminate the regeneration process if the
regeneration process is significantly unstable. For example, if the
downstream exhaust temperature exceeds a predetermined value or it
exceeds the upstream exhaust temperature by more than a
predetermined amount, then controller 28 may terminate the
regeneration process.
[0066] Controller 28 may be configured to log faults when the
downstream exhaust temperature exceeds a predetermined temperature
or when the downstream exhaust temperature exceeds the upstream
exhaust temperature by more than a predetermined amount. Controller
28 may also be configured to terminate the regeneration process if
the number of faults reaches a predetermined value (e.g., when
three faults have occurred).
[0067] System 16 may include a display 72. Display 72 may be
located at any suitable location on machine 10, such as, for
example, in operator station 11. Display 72 may be any kind of
display, including screen displays, such as, for example, cathode
ray tubes (CRTs), liquid crystal displays (LCDs), plasma screens,
and the like. Display 72 may be configured to display information
about operating parameters of system 16. In one embodiment, display
72 may include a warning indicator 74 (e.g., a warning lamp,
warning message, etc.). Controller 28 may be configured to
illuminate warning indicator 74 upon detection of the predetermined
amount of faults. As an alternative or in addition to display 72,
system 16 may include one or more audible alerts for conveying
information about operating parameters of system 16 to an operator.
In addition to providing visual feedback regarding operating
parameters of system 16, display 72 may also be configured to
display other information regarding system 16 or any other device
and/or system associated with machine 10. Display 72 may also be
configured to indicate when a regeneration event is occurring or
about to occur. Alternatively or additionally, display 72 may be
configured to display information regarding particulate loading
monitoring system 44.
[0068] FIG. 3 illustrates an exemplary schematic of particulate
loading monitoring system 44. Particulate loading monitoring system
44 may include a controller unit 76, which may include multiple
components, such as an A/D converter 78 and a synthesizer interface
80. In some embodiments, the functions and components of controller
unit 76 may be incorporated into controller 28. In other
embodiments, controller unit 76 may be separate from controller 28.
In such embodiments, controller unit 76 may include a Controller
Area Network (CAN) interface 82 configured to enable communication
with one or more other components, such as controller 28, via a CAN
datalink or any other suitable datalink or communication
format.
[0069] Synthesizer interface 80 may be configured to enable
communication with and thereby control of frequency synthesizer 46.
Synthesizer 46 may be configured to deliver RF signals to
particulate trap 19, as discussed above, along an interconnect 86,
such as a wire, cable, etc. Particulate loading monitoring system
44 may include a directional coupler 88 configured to monitor RF
signals traveling in both directions along interconnect 86. As
such, directional coupler 88 may be configured to measure the
amount of RF power delivered to transmitting probe 48 ("Forward
Power" 90). Particulate loading monitoring system 44 may be further
configured to relay this measurement of forward power back to
controller unit 76. Directional coupler 88 may also be configured
to measure the amount of RF power reflected by transmitting probe
48 ("Reflected Power" 92). Particulate loading monitoring system 44
may be further configured to relay this measurement of reflected
power back to controller unit 76. Particulate loading monitoring
system 44 may also be configured to measure the amount of RF power
received by receiving probe 50 ("Received Power" 94) and relay this
measurement back to controller unit 76. From these measurements of
forward power and received power, controller unit 76 may determine
the amount of power loss (i.e., RF signal loss) across filter
medium 24 of particulate trap 19.
[0070] Other aspects of system 16 may also be measured, such as
upstream pressure (96), downstream pressure (98), upstream
temperature (100), and downstream temperature (102). These and/or
other measurements may also be forwarded to controller unit 76 to
provide further information from which to assess the amount of
particulate matter accumulated in particulate trap 19.
[0071] Particulate loading monitoring system 44 may include other
signal processing components, as shown in an exemplary fashion in
FIG. 3. For example, particulate loading monitoring system 44 may
include a bandpass filter 104, one or more attenuators 106, one or
more short circuit protection devices 108, one or more amplifiers
109, and/or one or more log amps 110.
[0072] In some embodiments, particulate loading monitoring system
44 may be further configured to filter out all received RF signals
except for signals within a predetermined band of frequencies that
correspond with the frequencies of the signals transmitted by
transmitting probe 48. FIG. 4 illustrates an exemplary schematic of
a narrowband particulate loading monitoring system 112. Filtering
of the received RF signals may prevent interference from other RF
signals from external sources that may be detected by receiving
probe 50 but fall outside the predetermined range of frequencies
within which particulate loading monitoring system 44 is designed
to operate.
[0073] Narrowband system 112 may include many or all of the
components of particulate loading monitoring system 44 shown in
FIG. 3, and may further include additional signal processing and/or
filtering components. For example, narrowband system 112 may
include one or more tunable bandpass filters 114, one or more
frequency mixers 116, one or more narrow bandpass filters 118, and
an injection oscillator 120.
[0074] Tunable bandpass filters 114 may be employed to filter out
at least a portion of received RF signals that are outside of the
desired frequency band. Frequency mixers 116 may be employed to
convert a frequency swept RF signal to a single frequency, e.g.,
10.7 MHz. Such conversion may facilitate further signal processing.
Narrow bandpass filters 118 may be employed to filter out signals
that are not within a small margin of error from the single
frequency, for example, within 100-200 KHz of 10.7 MHz.
[0075] Narrowband system 112 may include a tracking signal
generator 122. In such narrowband embodiments, synthesizer 46 may
produce an offset frequency from that to be transmitted by
transmitting probe 48. The offset signal may be directed to
frequency mixers 116 for conversion of the received signal and the
reflected signal. Injection oscillator 120 may be employed to
convert the offset signal to the desired signal before being
delivered to transmitting probe 48. To make such a conversion,
injection oscillator 120 may include an oscillator 124 (e.g., 10.7
MHz), a bandpass filter 126, and a frequency mixer 128. The offset
signal may be mixed with signal from oscillator 124 to produce a
tracking signal to be applied to transmitting probe 48. Narrowband
system 112 may also include various other signal processing
devices, such as bandpass filters 104, attenuators 106, amplifiers
109, log amps 110, etc.
INDUSTRIAL APPLICABILITY
[0076] The disclosed particulate trap regeneration system 16 may be
suitable to enhance exhaust emissions control for engines. System
16 may be used for any application of an engine. Such applications
may include, for example, stationary equipment such as power
generation sets, or mobile equipment, such as vehicles. The
disclosed system may be used for any kind of vehicle, such as, for
example, automobiles, machines (including those for on-road, as
well as off-road use), and other heavy equipment.
[0077] The presently disclosed system may be mounted on board any
type of stationary or mobile equipment. In order for the components
of the disclosed system to be sized appropriately for on board
incorporation, the system may be configured to generate and measure
RF signals only in the specific range of frequencies with which the
system is designed to operate, rather than being configured to
generate a much wider range of frequencies. By focusing the
capabilities of the system components in such a manner, the size of
one or more system components may be scaled down. Focused
capabilities and smaller size of system components may make
particulate loading monitoring by an RF measurement technique
practical in terms of cost and size.
[0078] An exemplary method of regenerating particulate trap 19 may
include determining an amount of particulate matter trapped in
filter medium 24 of particulate trap 19. Such a determination may
be accomplished by transmitting radio frequency signals of
predetermined magnitude and predetermined frequency toward filter
medium 24 and receiving and measuring the magnitude of received
radio frequency signals that pass through filter medium 24. The
method may also include taking a temperature measurement indicative
of a temperature of particulate trap 19 at the time the radio
signals are received and determining, based on the measured
magnitude of received radio frequency signals, a particulate
loading value indicative of the amount of particulate matter
trapped in filter medium 24.
[0079] The method may also involve performing a temperature
compensation including modifying, based on the temperature
measurement, at least one of the following: the measured magnitude
of the received radio frequency signals that pass through filter
medium 24 or the particulate loading value. The temperature
compensation may involve a function based on the temperature
measurement and at least one of the measured magnitude of the
received radio frequency signals that pass through the filter
medium or the particulate loading value. An example of such a
function may be a third order polynomial. Alternatively, the
temperature compensation may include referring to a look-up table
based on the temperature measurement and at least one of the
following: the measured magnitude of the received radio frequency
signals that pass through the filter medium or the particulate
loading value.
[0080] The radio frequency signals that are transmitted toward, or
within, the filter medium 24 may greatly vary depending on the
distance the radio frequency signals may have to travel. For
particulate loading monitoring systems 44 having a transmitting
probe 48 and a receiving probe 50 located within the filter medium
24 and spaced relatively close together, frequencies of less than
about 500 MHz may be used. An exemplary band of frequencies that
may be transmitted may be about 100-400 MHz. In other systems 44
where the transmitting probe 48 may be sending radio frequency
signals to the receiving probe 50 through the entire distance of
the filter medium 24, the radio frequency signals may be between
700 MHz to 900 MHz. It is also anticipated that higher or lower
radio frequency signals may used depending on the application and
the distance of travel that may be required by the radio frequency
signals.
[0081] The particulate loading monitoring system 44 may also be
configured to wirelessly communicate sensor data from the
particulate trap 19 to a remotely located device, such as the
engine controller 15 and the like. These radio frequency signals
may utilize the exhaust conduit 20 as a waveguide, and the
frequencies of the radio frequency signals may be different for
each type of transmission. For example, a first radio frequency
across the filter medium 24 may occur between 700 MHz to 900 MHz,
while a second radio frequency signal may be sent along the exhaust
conduit 20 at a frequency of greater than 1.5 GHz. In an exemplary
embodiment, this may be 2.4 GHz. Alternatively, the transmitting
probe 48 could be located downstream of the filter medium 24 and
transmit a radio frequency signal across the filter medium 24 and
through the exhaust conduit 20 to be received by the receiving
probe 50 that may be connected to the engine controller 15. The
transmitting probe 48 and receiving probe 50 may be configured to
transmit and detect the magnitude of the radio frequencies across
the filter medium 24 in addition to transmitting and receiving
sensor data from sensors 52, 54, 56, 58. All of this data may be
transmitted at the same frequency, such as 2.4 GHz. The engine
controller 15 may take this data generated from the system 44 to
determine a value indicative of particulate loading of the filter
medium. Based upon this value, the engine controller may control
the regeneration process.
[0082] In a system 44 configured to use passive radio frequency
technology, the radio frequency reader 47 may emit a radio
frequency signal on the order of 2.4 GHz to be propagated along the
exhaust conduit 20 and into the particulate trap 19. The passive
sensors 52,54,56,58 and probe 50 may be polled by the reader 47 to
gather various data and emit a response. The response from the
sensors 52,54,56,58 and probe 50 may consist of modifying the
incoming signal to transmit information back to the reader 47.
Alternatively, it is contemplated the response from the sensors
52,54,56,58 and probe 50 may consist of a second radio frequency
signal, on the order of 2.4 GHz, such that the response is
propagated along the exhaust conduit 20 back to the reader 47.
[0083] In choosing the range of radio frequencies to be used
herein, a number of considerations may be evaluated. For example,
the amount of transmission loss over the selected frequency range
should provide for, among other things, suitable measurement
sensitivity (i.e., attenuation per unit of particulate matter
present) and a more linear response as a function of radio
frequency signal attenuation than is possible at a single
frequency. In instances where the radio frequency signals may be
transmitted wirelessly to remote devices, such as the engine
controller 15, it may be necessary to select a range of radio
frequencies with suitable measurement sensitivity and an adequate
signal to noise ratio. The selected range of frequencies should
also avoid problems associated with power source frequency drift
with time. Further, averaging reduces the effects of temperature on
accumulated particulate matter and filter permittivity, which would
otherwise require temperature compensation in single or narrow band
frequency methods. In addition, lower frequencies mean lower signal
attenuation (i.e., less signal loss) and lower device costs.
[0084] The method may further include determining a signal loss
value by comparing the measured magnitude of the received signals
of one or more frequencies to the magnitude of the transmitted
signals of the same one or more frequencies. Where a signal loss
value is determined, performing the temperature compensation may
include modifying the signal loss value based on the temperature
measurement.
[0085] The method may include delivering radio frequency signals to
transmitting probe 48 and detecting magnitudes of radio frequency
signals reflected by transmitting probe 48. The method may further
include determining the amount of particulate matter trapped in
filter medium 24 based on the detected magnitudes of radio
frequency signals reflected by transmitting probe 48.
[0086] The method may include filtering out all received radio
frequency signals except for signals within a predetermined band of
frequencies that correspond with the frequencies of the signals
transmitted by transmitting probe 48. The method may also include
communicating between controller 28 and at least one other
component of particulate trap regeneration system 16, such as the
engine controller 15, via a datalink. This datalink may be
wireless.
[0087] The method may also include activating regeneration device
25 in response to a determination that more than a predetermined
amount of particulate matter is trapped in filter medium 24 to
thereby reduce an amount of particulate matter in particulate trap
19. The method may further include activating regeneration device
25 in response to one or more other trigger conditions.
[0088] In some embodiments, the system may be configured to
activate regeneration device 25 when more than one trigger
condition is met. For example, the system may wait until both a
particulate loading threshold and a time-based trigger condition
are met before initiating a regeneration event. In other
embodiments, the system may be configured to initiate a
regeneration event when the first of multiple possible trigger
conditions is met.
[0089] The following is a description of an exemplary system that
is configured to initiate a regeneration event when the first of
multiple possible trigger conditions is met. In such a system, for
example, a simple time trigger (e.g., engine operation time) may
provide the utmost reliability as no physical characteristics need
to be sensed to monitor such a trigger condition. However,
depending on other factors, particulate loading in particulate trap
19 may reach a level warranting regeneration at an earlier time
than the interval at which the time trigger is set. In order to
prevent damage that could result from such a situation, a
backpressure or pressure differential trigger may be configured to
monitor for relatively higher levels of particulate loading. Thus,
in such cases where particulate loading has prematurely reached a
high level, a backpressure or pressure differential trigger may
trigger regeneration to remedy excessive particulate loading even
before a time trigger condition is met.
[0090] If, for whatever reason, particulate loading has prematurely
reached a high level, but has not caused a significant increase in
backpressure, an actual particulate loading monitoring system may
detect the actual amount of particulate matter accumulated in
filter medium 24. That is, system 16 may, in some embodiments, be
configured to measure the amount of particulates accumulated in
particulate trap 19 and initiate a regeneration event if the amount
of particulates accumulated in particulate trap 19 is above a
predetermined threshold level.
[0091] If, however, neither the backpressure trigger, nor the
particulate loading monitoring system successfully detect excessive
particulate loading in a given circumstance, then the time trigger
may serve to insure that regeneration occurs at relatively
conservative intervals. Further, regeneration may be triggered
manually if, for whatever reason, no other trigger conditions are
determined to be met, but an operator, owner, service technician,
etc. deems that a regeneration may be appropriate based on their
own observations.
[0092] It will be apparent to those having ordinary skill in the
art that various modifications and variations can be made in the
system and method of the present invention without departing from
the scope or spirit of the invention. Other embodiments of the
invention will be apparent to those having ordinary skill in the
art from consideration of the specification and practice of the
invention disclosed herein. It is intended that the specification
and examples be considered as exemplary only, with a true scope and
spirit of the invention being indicated by the following claims and
their equivalents.
* * * * *