U.S. patent application number 11/236486 was filed with the patent office on 2007-03-29 for exhaust treatment system having hydraulically-actuated air valve.
This patent application is currently assigned to Caterpillar Inc.. Invention is credited to Manoj H. Baweja, John D. Gierszewski, Rodney L. Rolffs.
Application Number | 20070068146 11/236486 |
Document ID | / |
Family ID | 37394391 |
Filed Date | 2007-03-29 |
United States Patent
Application |
20070068146 |
Kind Code |
A1 |
Rolffs; Rodney L. ; et
al. |
March 29, 2007 |
Exhaust treatment system having hydraulically-actuated air
valve
Abstract
An exhaust treatment system for a power source is disclosed. The
exhaust treatment system has an inlet configured to receive an
exhaust flow from the power source, a filtering medium configured
to remove particulate matter from the exhaust flow, and an outlet
configured to direct the exhaust flow from the filtering medium to
the atmosphere. The exhaust treatment system also has a heating
device configured to raise the temperature of the particulate
matter entrained within the filtering medium, a supply of
pressurized air, and a pilot-operated valve configured to
selectively direct the pressurized air to the heated particulate
matter.
Inventors: |
Rolffs; Rodney L.; (East
Peoria, IL) ; Baweja; Manoj H.; (Dunlap, IL) ;
Gierszewski; John D.; (Creve Coeur, IL) |
Correspondence
Address: |
CATERPILLAR/FINNEGAN, HENDERSON, L.L.P.
901 New York Avenue, NW
WASHINGTON
DC
20001-4413
US
|
Assignee: |
Caterpillar Inc.
|
Family ID: |
37394391 |
Appl. No.: |
11/236486 |
Filed: |
September 28, 2005 |
Current U.S.
Class: |
60/297 ; 60/285;
60/295; 60/301 |
Current CPC
Class: |
F01N 2370/04 20130101;
F01N 2260/14 20130101; F01N 3/36 20130101; F02B 37/00 20130101;
F01N 2270/04 20130101; F01N 13/017 20140601; F02D 41/029 20130101;
F01N 3/0253 20130101; F01N 3/34 20130101; F01N 3/32 20130101; F01N
2390/02 20130101 |
Class at
Publication: |
060/297 ;
060/295; 060/285; 060/301 |
International
Class: |
F01N 3/00 20060101
F01N003/00; F01N 3/10 20060101 F01N003/10 |
Claims
1. An exhaust treatment system for a power source, comprising: an
inlet configured to receive an exhaust flow from the power source;
a filtering medium configured to remove particulate matter from the
exhaust flow; an outlet configured to direct the exhaust flow from
the filtering medium to the atmosphere; a heating device configured
to raise the temperature of the particulate matter entrained within
the filtering medium; a supply of pressurized air; and a
pilot-operated valve configured to selectively direct the
pressurized air to the heated particulate matter.
2. The exhaust treatment system of claim 1, further including a
supply of pilot fluid, wherein the pilot operated valve includes a
valve element movable by the pilot fluid.
3. The exhaust treatment system of claim 2, wherein the pilot fluid
includes a lubricant of the power source.
4. The exhaust treatment system of claim 2, wherein the pilot fluid
includes a fuel of the power source.
5. The exhaust treatment system of claim 1, wherein the
pilot-operated valve is solenoid-actuated.
6. The exhaust treatment system of claim 1, wherein the heating
device is a fuel-powered burner.
7. The exhaust treatment system of claim 5, further including a
single power source controller in communication with the power
source and a solenoid of the pilot operated valve, the single power
source controller configured to control operation of the power
source and the pilot-operated valve.
8. A method of treating an exhaust flow of a power source,
comprising: directing the exhaust flow from the power source to a
filtering medium to remove particulate matter from the exhaust
flow; directing the exhaust flow from the filtering medium to the
atmosphere; raising the temperature of the particulate matter
entrained within the filtering medium; and regulating a flow of
pilot fluid to an air valve to selectively pass pressurized air to
the heated particulate matter.
9. The method of claim 8, wherein the pilot fluid includes a
lubricant of the power source.
10. The method of claim 8, wherein the pilot fluid includes a fuel
of the power source.
11. The method of claim 8, wherein regulating a flow of pilot fluid
includes pressurizing the pilot fluid and supplying the pilot fluid
to a first valve element to move the first valve element.
12. The method of claim 11, wherein regulating further includes
directing a current to a solenoid mechanism to move a second valve
element.
13. The method of claim 8, further including heating the entrained
particulate matter.
14. A work machine, comprising: a power source configured to
produce a power output and an exhaust flow; and an exhaust
treatment system configured to remove particulate matter from the
exhaust flow, the exhaust treatment system including: an inlet
configured to receive the exhaust flow; a filtering medium
configured to remove particulate matter from the exhaust flow; an
outlet configured to direct the exhaust flow from the filtering
medium to the atmosphere; a heating device configured to raise the
temperature of the particulate matter entrained within the
filtering medium; a supply of pressurized air; and a pilot-operated
valve configured to selectively direct the pressurized air to the
heated particulate matter.
15. The work machine of claim 14, further including a supply of
pilot fluid, wherein the pilot operated valve includes a valve
element movable by the pilot fluid.
16. The work machine of claim 15, wherein the pilot fluid includes
a lubricant of the power source.
17. The work machine of claim 15, wherein the pilot fluid includes
a fuel of the power source.
18. The work machine of claim 14, wherein the pilot-operated valve
is solenoid-actuated.
19. The work machine of claim 14, wherein the heating device is a
fuel-powered burner.
20. The work machine of claim 19, further including a single power
source controller in communication with the power source and a
solenoid of the pilot operated valve, the single power source
controller configured to control operation of the power source and
the pilot-operated valve.
Description
TECHNICAL FIELD
[0001] The present disclosure relates generally to an exhaust
treatment system and, more particularly, to an exhaust treatment
system having a hydraulically-actuated air valve.
BACKGROUND
[0002] Internal combustion 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 gaseous compounds and solid
particulate matter, which may include unburned carbon particulates
called soot. Due to increased attention on the environment, exhaust
emission standards have become more stringent and the amount of
particulate matter emitted from an engine may be regulated
depending on the type of engine, size of engine, and/or class of
engine. One method that has been implemented by engine
manufacturers to comply with the regulation of particulate matter
exhausted to the environment has been to remove the particulate
matter from the exhaust flow of an engine using a particulate trap.
A particulate trap is a filter designed to trap particulate matter
in, for example, a wire mesh or ceramic honeycomb filtering media.
Over time, the particulate matter may accumulate in the filtering
media, thereby reducing filter functionality and engine
performance.
[0003] Various regeneration techniques may be employed to manage
the accumulated particulate matter. For example, U.S. Pat. No.
5,090,200 (the U.S. Pat. No. '200 patent) issued to Arai on Feb.
25, 1992, describes a regeneration system for a particulate trap
provided in an exhaust pipe of an engine. The regeneration system
includes a heater provided on a front face of the particulate trap,
a blower to pressurize regeneration air, a solenoid-operated air
valve, and a bypass valve. When the particulate trap is saturated
with particulate matter, the bypass valve is opened and the heater
is turned on to initiate combustion. To facilitate the combustion
of the particulate matter, the blower is turned on and the air
valve is electronically controlled according to various input to
allow the pressurized regeneration air to blow toward the
operational heater.
[0004] Although the regeneration system of the U.S. Pat. No. '200
patent may sufficiently regenerate the particulate trap, the system
may be expensive and costly to operate. In particular, because the
solenoid directly opens the air valve against pressurized air, the
solenoid must be large to overcome the force of the high pressure
regeneration air. The large solenoid may increase the component
cost of the regeneration system, require complex and expensive
control systems, and require high currents that add to the
operating cost of the system and reduce efficiency of the machine
employing the system.
[0005] The disclosed exhaust treatment system is directed to
overcoming one or more of the problems set forth above.
SUMMARY OF THE INVENTION
[0006] In one aspect, the present disclosure is directed to an
exhaust treatment system. The exhaust treatment system includes an
inlet configured to receive an exhaust flow from the power source,
a filtering medium configured to remove particulate matter from the
exhaust flow, and an outlet configured to direct the exhaust flow
from the filtering medium to the atmosphere. The exhaust treatment
system also includes a heating device configured to raise the
temperature of the particulate matter entrained within the
filtering medium, a supply of pressurized air, and a pilot-operated
valve configured to selectively direct the pressurized air to the
heated particulate matter.
[0007] In another aspect, the present disclosure is directed to a
method of treating an exhaust flow of a power source. The method
includes directing the exhaust flow from the power source to a
filtering medium to remove particulate matter from the exhaust
flow, directing the exhaust flow from the filtering medium to the
atmosphere, and raising the temperature of the particulate matter
entrained within the filtering medium. The method also includes
regulating a flow of pilot fluid to an air valve to selectively
pass pressurized air to the heated particulate matter.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 is a diagrammatic illustration of a work machine
having an exemplary disclosed exhaust treatment system; and
[0009] FIG. 2 is a cross-sectional illustration of an exemplary
disclosed pilot-operated air valve for the exhaust treatment system
of FIG. 1.
DETAILED DESCRIPTION
[0010] FIG. 1 illustrates an exemplary work machine 10 having
multiple systems and components that cooperate to accomplish a
task. Work machine 10 may perform some type of operation associated
with an industry such as mining, construction, farming,
transportation, power generation, or any other industry known in
the art. For example, work machine 10 may embody a mobile work
machine such as an excavator, a dozer, a loader, a backhoe, a motor
grader, a dump truck, or any other earth moving machine. Work
machine 10 may alternatively embody a stationary work machine such
as a generator set, a furnace, or another suitable stationary
machine. Work machine 10 may include a power source 12, an air
induction system 14, and an exhaust treatment system 16.
[0011] Power source 12 may include a combustion engine having
multiple subsystems to produce a mechanical or electrical power
output and a flow of exhaust gas. For example, power source 12 may
include a diesel engine, a gasoline engine, a gaseous fuel-powered
engine, or any other type of combustion engine known in the art.
Power source 12 may also include a lubrication system 18 and a fuel
system 20. It is contemplated that power source 12 may include
additional and different subsystems such as, for example, a cooling
system, a drive system, a guidance system, or any other appropriate
system.
[0012] Lubrication system 18 may include components that circulate
a lubricant throughout portions of power source 12. Specifically,
lubrication system 18 may include a pumping mechanism 22 configured
to draw the lubricant from a sump 24 via a supply line 26 and
pressurize the lubricant to a predetermined pressure level. Pumping
mechanism 22 may embody a variable or fixed displacement pump that
is electrically driven or coupled to power source 12 in a direct or
indirect drive configuration. The lubricant may include, for
example, engine oil. Lubrication system 18 may direct the
pressurized lubricant from pumping mechanism 22 to the components
of power source 12 via a fluid passageway 28, and return the
lubricant to sump 24. A check valve 31 may be disposed within fluid
passageway 28 to provide one-directional flow from pumping
mechanism 22.
[0013] Fuel system 20 may include components that cooperate to
deliver injections of pressurized fuel into combustion chambers
(not shown) of power source 12. Specifically, fuel system 20 may
include a tank 30 configured to hold a supply of fuel, and a fuel
pumping arrangement configured to pressurize the fuel and direct
the pressurized fuel to fuel injector means (not shown) associated
with power source 12.
[0014] Tank 30 may constitute a reservoir configured to hold a
supply of fuel. The fuel may include, for example, diesel fuel,
gasoline, kerosene, a heavy fuel, or any other type of fuel known
in the art. One or more systems within work machine 10 may draw
fuel from and return fuel to tank 30. It is also contemplated that
fuel system 20 may be connected to multiple separate fuel tanks, if
desired.
[0015] The fuel pumping arrangement may include one or more pumping
devices that function to increase the pressure of the fuel. In one
example, the fuel pumping arrangement may include a low pressure
source 32 and a high pressure source 34 disposed in series and
fluidly connected by way of a fuel line 36. Low pressure source 32
may embody a transfer pump configured to provide low pressure feed
to high pressure source 34, while high pressure source 34 may
receive the low pressure feed and increase the pressure of the fuel
to the range of about 40-190 MPa. High pressure source 34 may be
connected to power source 12 by way of a fuel line 37. A check
valve 38 may be disposed within fuel line 37 to provide
one-directional flow of fuel from the fuel pumping arrangement to
power source 12.
[0016] One or both of low and high pressure sources 32, 34 may be
operably connected to and driven by power source 12. In particular,
low and/or high pressure sources 32, 34 may be connected with power
source 12 in any manner readily apparent to one skilled in the art
where an output rotation of power source 12 will result in a
corresponding rotation of a drive shaft of low pressure source 32
and high pressure source 34. It is contemplated, however, that one
or both of low and high pressure sources 32, 34 may alternatively
be driven electrically, hydraulically, pneumatically, or in any
other appropriate manner.
[0017] Air induction system 14 may include components configured to
introduce compressed air into a combustion chamber (not shown) of
power source 12. For example, air induction system 14 may include
an air filter 40 and a compressor 42. It is contemplated that air
induction system 14 may include different or additional components
than described above such as, for example, inlet bypass components,
venturis, after and/or inter-stage air coolers, exhaust gas
recirculation components, and other known components.
[0018] Air filter 40 may be configured to remove or trap debris
from air flowing into power source 12. For example, air filter 40
may include a full-flow filter, a self-cleaning filter, a
centrifuge filter, an electrostatic precipitator, or any other type
of air filtering device known in the art. It is contemplated that
more than one air filter 40 may be included within air induction
system 14 and disposed in a series or parallel arrangement.
[0019] Compressor 42 may be configured to compress the air flowing
into power source 12 to a predetermined pressure. In particular,
compressor 42 may include a fixed geometry type compressor, a
variable geometry type compressor, or any other type of compressor
known in the art disposed downstream of air filter 40. Compressor
42 may be connected to air filter 40 by way of an inlet passageway
44 and to power source 12 by way of an inlet manifold 46. It is
contemplated that more than one compressor 42 may be included and
disposed in parallel or in series relationship. It is further
contemplated that compressor 42 may be omitted, for example, when a
non-compressed air induction system is desired.
[0020] Exhaust treatment system 16 may include a means for
directing the flow of exhaust gases from power source 12 to the
atmosphere, and for treating the exhaust flow. For example, exhaust
treatment system 16 may include a turbine 48 connected to receive
exhaust from power source 12, a particulate trap 50 disposed
downstream of turbine 48, and a regeneration subsystem 52 located
therebetween. It is contemplated that exhaust treatment system 16
may include additional and/or different components such as, for
example, NOx absorbers or other catalytic devices, attenuation
devices, recirculation systems, and other means known in the art
for directing exhaust flow from power source 12 and/or for treating
the flow of exhaust.
[0021] Turbine 48 may be connected to drive compressor 42. In
particular, as the hot exhaust gases from power source 12 expand
against blades (not shown) of turbine 48, turbine 48 may rotate and
drive compressor 42. It is contemplated that more than one turbine
48 may alternatively be included within exhaust treatment system 16
and disposed in a parallel or series relationship, if desired. It
is also contemplated that turbine 48 may be omitted and compressor
42 driven directly by power source 12 mechanically, hydraulically,
electrically, or in any other manner known in the art, if
desired.
[0022] Particulate trap 50 may include one or more filtering
elements 54 configured to remove particulate matter from the
exhaust flow. Specifically, filtering elements 54 may embody deep
bed ceramic-type elements configured to accumulate particulate
matter throughout a thickness of the element, shallow bed type
elements such as impingement type metallic or ceramic meshes
configured to accumulate particulate matter at a surface of the
element, or any other suitable type of filtering element know in
the art. The size of the pore and/or mesh openings of filtering
elements 54 may vary and be selected depending on a particular
application. It is contemplated that filtering elements 54 may
include pleats to increase a filtration area, may be catalyzed to
reduce an oxidation temperature, may include an electrostatic
device, and/or may be electrically conductive to facilitate a
regeneration process, if desired.
[0023] Regeneration subsystem 52 may include components configured
to regenerate, particulate trap 50. Specifically, regeneration
subsystem 52 may include a regeneration initiation device 56, a
venturi 58, and an air valve 60. It is contemplated that
regeneration subsystem 52 may include additional and different
components such as, for example, blocking or bypass elements,
catalytic devices, or any other appropriate regeneration
components. It is further contemplated that venturi 58 may be
omitted, if desired.
[0024] Regeneration initiation device 56 may be configured to
initiate regeneration of filtering elements 54 in response to one
or more input. In one example, regeneration initiation device 56
may embody a fuel injector mechanism having a fuel valve connected
to high pressure source 34 by way of an auxiliary supply line 62.
In response to the one or more input, the fuel valve may direct a
pressurized stream of fuel into venturi 58 and toward filtering
elements 54. As the pressurized stream of fuel ignites, the
temperature of the particulate matter entrained within filtering
elements 54 may be elevated to combustion. The one or more input
may include, for example, an elapsed time period, an exhaust
temperature, a pressure differential across filtering elements 54,
an exhaust back pressure, or any other suitable condition. It is
contemplated that regeneration initiation device 56 may
alternatively embody an electrical heating element, an engine valve
timing controller, a catalyst injection device, or any other
initiation device known in the art.
[0025] Venturi 58 may be configured to constrict the flow of
exhaust within exhaust treatment system 16, thereby increasing a
speed of the exhaust gasses passing through venturi 58 and, in
turn, reducing a pressure of the flow of exhaust through the
constriction. Venturi 58 may be fluidly disposed between turbine 48
and particulate trap 50 where the reduced pressure may function to
draw the pressurized stream of fuel from regeneration initiation
device 56 and pressurized air from air valve 60.
[0026] Air valve 60 may be configured to selectively allow
pressurized air to flow from compressor 42 toward filtering
elements 54 in response to an electrical input and a fluid
pressure. In particular, air valve 60 may be fluidly connected to
compressor 42 by way of a fluid passageway 64 and fluidly connected
to pumping mechanism 22 by way a pilot passageway 65. As
illustrated in FIG. 2, air valve 60 may embody a solenoid-actuated,
pilot-operated valve having a solenoid mechanism 66, a pilot valve
element 68, and a main poppet element 70. Solenoid mechanism 66 may
electrically actuate air valve 60 to regulate a flow of pilot fluid
through pilot passageway 65 such that pressurized air is allowed to
flow from compressor 42 through fluid passageway 64 and air valve
60 to filtering elements 54. It is contemplated that air valve 60
may include additional components known in the art such as, for
example, a common housing, sealing elements, guide elements,
fasteners, check valves, relief valve elements, makeup valve
elements, pressure balancing passageways, and other such
components.
[0027] Solenoid mechanism 66 may be electrically connected to a
controller (not shown) and include an armature 72 with a connected
pin 74, both movable against the bias of a pilot return spring 76
from a neutral state to an energized state. Armature 72 and
connected pin 74 may move from the neutral state to the energized
state in response to an applied current.
[0028] Pilot valve element 68 may engage pin 74 to follow the
movement of armature 72 and pin 74, thereby selectively causing an
increase or decrease in pilot fluid pressure within air valve 60.
In particular, pilot valve element 68 may include a central bore
78, a set of radial passageways 80, and a centrally-located
external annular groove 82. The pilot fluid may enter air valve 60
from pilot passageway 65 via an inlet port 84, flow from annular
groove 82 to central bore 78 via the set of radial passageways 80,
and exit both ends of pilot valve element 68. When armature 72 and
connected pin 74 are in the neutral position, pilot valve element
68 may be biased by a main return spring 86 toward a closed
position at which the lubricant may be blocked from exiting air
valve 60 resulting in a buildup of pressure within air valve 60.
However, when armature 72 and connected pin 74 are urged toward the
energized position, pilot valve element 68 may be likewise moved
against the bias of main return spring 86 toward an open position
at which the pilot fluid within air valve 60 is allowed to drain to
sump 24 via an outlet port 83, thereby reducing the pressure within
air valve 60.
[0029] Main poppet element 70 may include a nose portion 88
pivotally connected to a piston portion 90 that is movable in
response to the pressure changes within air valve 60. Specifically,
nose portion 88 may be connected to piston portion 90 by way of a
pivot pin 92, and may be configured to selectively engage a valve
seat 94. When nose portion 88 is engaged with valve seat 94, air
from fluid passageway 64 may be substantially prevented from
flowing toward filter elements 54 via venturi 58. However, when
nose portion 88 is moved away from valve seat 94, pressurized air
may freely flow through fluid passageway 64 and venturi 58 to aid
in the regeneration of filtering elements 54. When the pilot fluid
pressure acting on piston portion 90 exceeds the closing forces of
the pressurized air acting on nose portion 88, nose portion 88 may
remain engaged with valve seat 94. However, when the pilot fluid
pressure within air valve 60 drops below the opening forces acting
on nose portion 88, nose and piston portions 88, 90 may together be
moved toward the open position to allow the pressurized air to flow
from fluid passageway 64 through venturi 58 toward filtering
elements 54. A sealing device 96 disposed between nose portion 88
and piston portion 90 may maintain separation between the
pressurized air and the pressurized lubricant.
INDUSTRIAL APPLICABILITY
[0030] The disclosed exhaust treatment system may be applicable to
any combustion-type device such as, for example, an engine, a
furnace, or any other combustion device known in the art where the
removal of particulate matter from an exhaust flow is desired.
Exhaust treatment system 16 may be a simple, inexpensive, and
efficient solution for reducing the amount of particulate matter
exhausted to the environment without adversely affecting back
pressure within the exhaust system. The operation of exhaust
treatment system 16 will now be explained.
[0031] Atmospheric air may be drawn into air induction system 14
via compressor 42 where it may be pressurized to a predetermined
level before entering the combustion chamber of power source 12.
Fuel may be mixed with the pressurized air before or after entering
the combustion chamber. This fuel-air mixture may then be combusted
by power source 12 to produce mechanical work and an exhaust flow
containing gaseous compounds and solid particulate matter. The
exhaust flow may be directed via turbine 48 from power source 12
through filtering elements 54, where a substantial portion of the
particulate matter entrained with the exhaust may be filtered from
the exhaust flow. Over time, the particulate matter will build up
within filtering elements 54 and, if left unchecked, could be
significant enough to partially or even fully restrict the flow of
exhaust through filtering elements 54, allowing for pressure within
exhaust treatment system 16 to increase. An increase in the back
pressure of power source 12 could reduce the ability to draw in
fresh air, resulting in decreased performance of power source
12.
[0032] To accommodate the buildup of particulate matter within
particulate trap 50, filtering elements 54 may be regenerated.
Regeneration may be based on a triggering condition such as for
example, a lapsed time of power source operation, a pressure
differential measured across particulate trap 50, a temperature or
pressure of the exhaust flow from power source 12, or any other
condition known in the art.
[0033] To regenerate filtering elements 54, a stream of fuel from
regeneration initiation device 56 and a flow of pressurized air
from air valve 60 may be directed toward filtering elements 54.
Under the high temperature environment within exhaust treatment
system 16, the fuel/air mixture directed toward filtering elements
54 may ignite and increase the temperature of the entrained
particulate matter to combustion.
[0034] To direct the flow of pressurized air toward filtering
elements 54, a current may be applied to solenoid mechanism 66 that
urges armature 72 and connected pin 74 downward toward main poppet
element 70. As armature 72 and pin 74 move downward, pilot element
68 may be forced to the open position to drain the pressurized
lubricant from air valve 60. As the pressure of the lubricant
within air valve 60 decreases, the force exerted by the decreasing
pressure on piston portion 90 may drop below the opening forces
acting on nose portion 88, thereby causing nose portion 88 to move
away from valve seat 94. As nose portion 88 moves away from valve
seat 94, pressurized air may be allowed to flow from fluid
passageway 64 toward filtering elements 54 via venturi 58.
[0035] Because air valve 60 is pilot-operated, the component and
operating costs of exhaust treatment system 16 may be minimal.
Specifically, because the force required to operate air valve 60 is
derived from lubricant already pressurized for use within power
source 12, the size of the solenoid utilized to actuate air valve
60 may be reduced, as compared to systems where the solenoid must
exert the opening and closing forces. In addition, because the
solenoid may be small, it may require little current to operate air
valve 60. The reduced current requirements of air valve 60 may
reduce the operating cost associated with exhaust treatment system
16 and, thereby, improve efficiency of work machine 10.
[0036] It will be apparent to those skilled in the art that various
modifications and variations can be made to the disclosed exhaust
treatment system. Other embodiments will be apparent to those
skilled in the art from consideration of the specification and
practice of the disclosed exhaust treatment system. It is intended
that the specification and examples be considered as exemplary
only, with a true scope being indicated by the following claims and
their equivalents.
* * * * *