U.S. patent application number 15/009025 was filed with the patent office on 2017-08-03 for system and method for purging reductant in a reductant dosing system.
This patent application is currently assigned to Caterpillar Inc.. The applicant listed for this patent is Caterpillar Inc.. Invention is credited to Dustin Landwehr, Satya Ramakrishna Manda Venkata Naga.
Application Number | 20170218819 15/009025 |
Document ID | / |
Family ID | 59387501 |
Filed Date | 2017-08-03 |
United States Patent
Application |
20170218819 |
Kind Code |
A1 |
Landwehr; Dustin ; et
al. |
August 3, 2017 |
System and Method for Purging Reductant in a Reductant Dosing
System
Abstract
A reductant supply system includes a pump having a suction side
and a discharge side, and a tank that holds a reductant therein. A
reductant supply passageway extends from the tank to the suction
side of the pump so as to supply the reductant from the tank to the
pump. Further, a reductant discharge passageway extends from the
discharge side of the pump and is configured to supply the
reductant to a reductant injection assembly that injects the
reductant into an exhaust stream of an engine. The system further
includes purge componentry that connects the reductant supply
passageway to an ambient air source during a purging operation such
that the reductant supply system draws air from the air source
sequentially through the purge passageway, the reductant supply
passageway, and the pump assembly to purge at least the reductant
supply passageway and the pump assembly during the purging
operation.
Inventors: |
Landwehr; Dustin; (Kewanee,
IL) ; Manda Venkata Naga; Satya Ramakrishna; (Dunlap,
IL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Caterpillar Inc. |
Peoria |
IL |
US |
|
|
Assignee: |
Caterpillar Inc.
Peoria
IL
|
Family ID: |
59387501 |
Appl. No.: |
15/009025 |
Filed: |
January 28, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
Y02T 10/24 20130101;
F01N 2610/1413 20130101; F01N 3/2066 20130101; F01N 2610/1406
20130101; F01N 2610/02 20130101; F01N 2610/1453 20130101; F01N
2610/1493 20130101; F01N 2610/1433 20130101 |
International
Class: |
F01N 3/20 20060101
F01N003/20 |
Claims
1. A reductant supply system, comprising: a tank defining a cavity,
the cavity configured to hold a reductant; a pump assembly having a
suction side that is fluidly coupled to the tank, and having a
suction side that is configured to fluidly couple to a reductant
injection assembly, the reductant injection assembly configured to
inject the reductant into an exhaust stream of an engine; a
reductant supply passageway that extends from the tank to the
suction side of the pump assembly so as to fluidly couple the tank
to the pump assembly; and a purge passageway connected to the
reductant supply passageway between an inlet of the reductant
supply passageway and the pump assembly, the purge passageway
configured to selectively couple the pump assembly to an ambient
air source during a purging operation such that the pump assembly
is configured to draw air from the ambient air source through both
the reductant supply passageway and the pump assembly during the
purging operation to purge the reductant from the reductant supply
passageway and the pump assembly.
2. The reductant supply system of claim 1, wherein the purge
passageway includes a valve that selectively couples the reductant
supply passageway to the ambient air source during the purging
operation, wherein the ambient air source is an environment outside
of the tank.
3. The reductant supply system of claim 1, further comprising a
reductant return passageway that is selectively configurable to
return reductant from the suction side of the pump assembly back to
the tank during the purge operation.
4. The reductant supply system of claim 3, further comprising a
reductant discharge passageway fluidly coupled to the suction side
of the pump assembly, wherein the reductant return passageway is
selectively connectable to the reductant discharge passageway
between the pump assembly and the reductant injection assembly.
5. The reductant supply system of claim 1, comprising a cabinet
that houses the tank, the pump assembly, the reductant supply
passageway, and the purge passageway.
6. The reductant supply system of claim 5, wherein the cabinet
further houses a reductant discharge passageway fluidly coupled to
the suction side of the pump assembly, and the reductant discharge
passageway includes a port that extends through a wall of the
cabinet so as to removably couple the reductant discharge
passageway to the reductant injection assembly.
7. The reductant supply system of claim 5, further comprising a
reductant replenishment passageway configured to removably couple
the tank to a second tank that is spaced from the cabinet so as to
replenish the reductant in the tank.
8. The reductant supply system of claim 1, further comprising a
compressed gas passageway configured to selectively connect a
compressed gas source to the reductant injection assembly.
9. A reductant supply system comprising a reductant dosing cabinet,
the reductant dosing cabinet comprising: a tank that defines a
cavity, the cavity configured to hold a reductant; a pump assembly
having a suction side that is fluidly coupled to the tank and a
suction side that is configured to fluidly couple to a reductant
injection assembly that injects the reductant into an exhaust
stream of an engine; a reductant replenishment passageway
configured to fluidly couple the tank to a reductant replenishment
assembly so as to replenish the reductant in the tank, wherein the
reductant replenishment assembly is spaced from, and external to,
the reductant dosing cabinet; and a purge passageway configured to
selectively couple the suction side of the pump assembly to the
reductant replenishment assembly during a purge operation so as to
return the reductant from both the tank and the pump assembly to
the reductant replenishment assembly during the purge
operation.
10. The reductant supply system of claim 9, wherein the reductant
dosing cabinet includes a reductant discharge passageway fluidly
coupled to the suction side of the pump assembly, and the reductant
dosing cabinet includes at least one valve that is selectively
configurable to supply the reductant to the reductant injection
assembly during a dosing operation and divert the reductant to the
purge passageway during the purge operation.
11. The reductant supply system of claim 9, wherein the reductant
replenishment passageway includes a port that extends through a
wall of the cabinet so as to removably couple the reductant
replenishment assembly to the tank.
12. The reductant supply system of claim 11, wherein the reductant
replenishment assembly includes a second tank, spaced from the
reductant dosing cabinet, the second tank defining a second cavity
that has a maximum volume configured to hold the reductant, wherein
the maximum volume of the second tank is greater than a maximum
volume of the tank.
13. The reductant supply system of claim 12, wherein the reductant
replenishment assembly includes a pump that is configured to flow
the reductant from the second tank to the tank.
14. The reductant supply system of claim 9, wherein the reductant
dosing cabinet further comprises a reductant discharge passageway
fluidly coupled to the suction side of the pump assembly, and the
reductant discharge passageway includes a port that extends through
a wall of the reductant dosing cabinet so as to removably couple
the reductant discharge passageway to the reductant injection
assembly.
15. The reductant supply system of claim 9, further comprising a
compressed gas passageway configured to fluidly couple a compressed
gas source to the reductant injection assembly.
16. A method of purging reductant from a reductant dosing cabinet,
the method comprising steps of: coupling the reductant dosing
cabinet to a reductant injection assembly that injects the
reductant into an exhaust stream of an engine and to a reductant
replenishment assembly that is spaced from, and external to, the
reductant dosing cabinet; fluidly coupling a suction side of a pump
assembly of the reductant dosing cabinet to the reductant
replenishment assembly; and operating the pump assembly so as purge
the reductant in both a tank of the reductant dosing cabinet that
is coupled to a suction side of the pump assembly and the pump
assembly to the reductant replenishment assembly.
17. The method of claim 16, wherein: coupling the reductant dosing
cabinet includes coupling a reductant discharge passageway between
the suction side of the pump assembly and the reductant injection
assembly; and fluidly coupling the suction side of the pump
assembly includes selectively configuring at least one valve of the
reductant dosing cabinet to divert the reductant away from the
reductant injection assembly and to the purge passageway during the
purge operation.
18. The method of claim 16, wherein: coupling the reductant dosing
cabinet includes coupling a reductant discharge passageway between
the suction side of the pump assembly and the reductant injection
assembly; and the method further comprises steps of: fluidly
coupling the reductant discharge passageway to a reductant return
passageway between the pump assembly and the reductant injection
assembly; and flowing compressed gas from the reductant injection
assembly through the reductant discharge passageway and the
reductant return passageway so as to force reductant in the
reductant discharge passageway and the reductant return passageway
back to the tank.
19. The method of claim 16, wherein operating the pump assembly
includes flowing air in the tank through the pump assembly so as to
force the reductant in the pump assembly to flow to the reductant
replenishment assembly.
20. The method of claim 19, comprising drawing air into a vent of
the tank so as to fill a space in the cavity of the tank that was
previously occupied by the reductant.
Description
TECHNICAL FIELD
[0001] The present disclosure relates to the treatment of exhaust
gases generated by internal combustion engines, and more
specifically to reductant dosing systems and methods.
BACKGROUND
[0002] Reductant dosing systems are typically used to reduce
nitrogen oxide (NO.sub.x) emissions in large machines where space
and weight considerations are not a concern, such as, for example,
in locomotives and stationary power generation applications. The
reductant is stored in a tank located on the machine and, as the
machine operates and produces exhaust, the reductant is pumped from
the tank into the machine's exhaust system. The reductant reacts
with exhaust at high temperatures to affect a selective catalytic
reduction (SCR) of NOx within the exhaust.
[0003] A possible shortcoming of dosing systems relates to the
ambient temperatures at which some reductants freeze (about
12.degree. F.). When the reductant freezes, it may expand within
the dosing system, possibly causing damage to and/or clogging of
intricate components such as injector nozzles. One way to inhibit
freezing is to purge the system after use.
[0004] U.S. Pat. No. 8,291,926 (the '926 patent) by Thiagarajan et
al. discloses an exemplary reductant dosing system. Specifically,
the '926 patent discloses a reductant storage tank that is
connected to an exhaust system via a pump and a passageway.
Reductant is injected into the exhaust system via an injection
device located on the passageway. The '926 patent also discloses a
purging system that purges reductant from at least a portion of the
passageway using compressed air.
SUMMARY
[0005] In one aspect, a reductant supply system comprises a tank
and a pump assembly. The tank defines a cavity configured to hold a
reductant therein. The pump assembly has a suction side that is
fluidly coupled to the tank, and has a discharge side that is
configured to fluidly couple to a reductant injection assembly that
injects the reductant into an exhaust stream of an engine. The
reductant supply system further comprises a reductant supply
passageway and a purge passageway. The reductant supply passageway
extends from the tank to the suction side of the pump assembly so
as to fluidly couple the tank to the pump assembly. The purge
passageway is connected to the reductant supply passageway between
an inlet of the reductant supply passageway and the pump assembly.
Further, the purge passageway is configured to selectively couple
the pump assembly to an ambient air source during a purging
operation such that the pump assembly draws air from the ambient
air source through the reductant supply passageway and the pump
assembly during the purging operation to purge the reductant supply
passageway and the pump assembly.
[0006] In another aspect, a reductant supply system comprises a
reductant dosing cabinet. The reductant dosing cabinet comprises a
local tank and a pump assembly. The local tank defines a cavity
that is configured to hold a reductant therein. The pump assembly
has a suction side and a discharge side. The suction side that is
fluidly coupled to the local tank, and the discharge side is
configured to fluidly couple to a reductant injection assembly that
injects the reductant into an exhaust stream of an engine. The
reductant dosing cabinet further comprises a reductant
replenishment passageway configured to fluidly couple the local
tank to a reductant replenishment assembly so as to replenish the
reductant in the local tank, wherein the reductant replenishment
assembly is spaced from, and external to, the reductant dosing
cabinet. The reductant dosing cabinet yet further comprises a
reductant return passageway that is configured to selectively
couple the discharge side of the pump to the reductant
replenishment assembly during a purge operation so as to return the
reductant from both the local tank and the pump to the reductant
replenishment assembly during the purge operation.
[0007] Yet another aspect is a method of purging reductant from a
reductant dosing cabinet. The method comprises coupling the
reductant dosing cabinet to a reductant injection assembly that
injects the reductant into an exhaust stream of an engine and to a
reductant replenishment assembly that is spaced from, and external
to, the reductant dosing cabinet. The reductant dosing cabinet
comprises a local tank and a pump assembly. The local tank defines
a cavity configured to hold a reductant therein. The pump assembly
has a suction side that is fluidly coupled to the local tank, and
has a discharge side that is selectively connectable to the
reductant injection assembly. The method further comprises fluidly
coupling the discharge side of the pump assembly to the reductant
replenishment assembly, and operating the pump assembly so as purge
the reductant in the local tank and the pump assembly to the
reductant replenishment assembly.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] The foregoing summary, as well as the following detailed
description of embodiments of the application, will be better
understood when read in conjunction with the appended drawings. For
the purposes of illustrating the methods and apparatuses of the
present application, there is shown in the drawings representative
embodiments. It should be understood, however, that the application
is not limited to the precise methods and apparatuses shown. In the
drawings:
[0009] FIG. 1 shows a simplified schematic diagram of a reductant
supply system according to one embodiment;
[0010] FIG. 2 shows a simplified schematic diagram of a reductant
supply system according to another embodiment;
[0011] FIG. 3 shows a simplified schematic diagram of a reductant
supply system according to yet another embodiment; and
[0012] FIG. 4 shows a simplified schematic diagram of an engine
system including a reductant supply system according to one
embodiment.
DETAILED DESCRIPTION
[0013] Certain terminology is used in the following description for
convenience only and is not limiting. The words "right", "left",
"lower" and "upper" designate directions in the drawings to which
reference is made. The words "inner" or "distal" and "outer" or
"proximal" refer to directions toward and away from, respectively,
the engine and related parts thereof. The terminology includes the
above-listed words, derivatives thereof and words of similar
import.
[0014] As a general overview, reductant supply systems and methods
of operating the same are disclosed herein. Each reductant supply
system includes dosing componentry and is selectively configurable
to perform dosing operations, whereby the dosing componentry
supplies the reductant to an engine exhaust stream. For example,
the dosing componentry can include a local tank configured to store
reductant, reductant passageways fluidly coupling the local tank to
a reductant injection assembly that injects the reductant into an
engine exhaust stream, and a pump assembly configured to draw the
reductant from the local tank and supply the reductant to the
reductant injection assembly via the reductant passageways.
Further, each reductant supply system includes purge componentry
and is selectively configurable perform purging operations, whereby
the purge componentry is used to purge reductant from the dosing
componentry.
[0015] Referring to FIGS. 1 to 3, simplified schematic diagrams of
reductant supply system 100, 100', and 100'' according to various
embodiments are shown. Each reductant supply system 100, 100', and
100'' is configured to supply reductant, such as (without
limitation) liquid urea or ammonia, to an exhaust stream of an
engine. Each reductant supply system 100, 100', and 100'' includes
a reductant dosing assembly 102, 102', and 102''. Further, each
reductant supply system 100, 100', and 100'' can include one or
more of a reductant injection assembly 104, a compressed gas
assembly 106, and a reductant replenishment assembly 108, each in
fluid communication with the reductant dosing assembly 102, 102',
and 102''.
[0016] It will be understood that, in some embodiments, the
reductant supply system 100, 100', and 100'' can include only the
reductant dosing assembly 102, 102', and 102'', while in other
embodiments, the reductant supply system 100, 100', and 100'' can
include the reductant dosing assembly 102, 102', and 102'' and one
or more of the reductant injection assembly 104, the compressed gas
assembly 106, and the reductant replenishment assembly 108. As will
be described in further detail below, reductant supply systems 100,
100', and 100'' are generally similar to one another. However, each
reductant supply system 100, 100', and 100'' includes different
reductant purge componentry configured to purge reductant within
the reductant dosing assembly 102, 102', and 102'' to prevent
freezing of the reductant.
[0017] Each reductant dosing assembly 102, 102', and 102'' includes
a reductant dosing cabinet 110 that houses or otherwise supports
the components of the reductant dosing assembly 102, 102', and
102''. Thus, each reductant dosing assembly 102, 102', and 102''
can be referred to as a reductant dosing cabinet, although
alternative embodiments are not limited to cabinets. Each reductant
dosing cabinet 110 includes at least one wall 112 having an
interior surface 112a and an exterior surface 112b. The interior
surface 112a defines a cavity 113 in which the components of the
reductant dosing assembly 102, 102', and 102'' are housed. Each
reductant dosing assembly 102, 102', and 102'' includes at least
one, such as a plurality of ports 150, 164, 170, and 178, each of
which provides a passageway through the at least one wall 112 from
an interior of the reductant dosing cabinet 110 to an exterior of
the reductant dosing cabinet 110. The ports 150, 164, 170, and 178
may be supported by, or otherwise mounted to, at least one of the
interior surface 112a, the exterior surface 112b, and an inner
surface of the at least one wall 112 that extends between the
internal and exterior surfaces 112a and 112b and defines an opening
through the at least one wall 112. Each port can include a coupling
that is configured so as to enable the reductant dosing assembly
102, 102', and 102'' to be removably connectable to, and placed in
fluid communication with, one of the reductant injection assembly
104, the compressed gas assembly 106, and the reductant
replenishment assembly 108. Thus, the reductant dosing assembly
102, 102', and 102'' can be a separable, self-contained unit that
can be installed in various engines and various reductant supply
systems.
[0018] Each reductant dosing assembly 102, 102', and 102'' includes
the local tank 114 and a dosing pump assembly 138 housed within, or
otherwise supported by, the reductant dosing cabinet 110. Each
reductant dosing assembly 102, 102', and 102'' can further include
a reductant supply passageway 132, a reductant discharge passageway
162, a reductant replenishment passageway 146, and a compressed gas
supply passageway 172 housed within, or otherwise supported by, the
reductant dosing cabinet 110. However, in alternative embodiments,
one or more of these components may be omitted (e.g., when one or
both of the compressed gas assembly 106 and the reductant
replenishment assembly 108 is omitted).
[0019] The local tank 114 of each reductant dosing assembly 102,
102', and 102'' defines a local tank cavity 116 having a maximum
volume that is configured to hold the reductant. The local tank 114
can also include a tank manifold 120 that supports or defines a
reductant supply port 124 and a reductant replenishment inlet port
126 (in embodiments that employ the reductant replenishment
assembly 108). In at least some embodiments, the tank manifold 120
is supported by an upper, exterior surface 112b of the local tank
114. The local tank 114 can also include a vent 118, a level sensor
122, a heater 128, and a manual fill port 130, although one or more
of these components can be omitted.
[0020] In each reductant dosing assembly 102, 102', and 102'', the
reductant supply passageway 132 fluidly couples the local tank 114
to the dosing pump assembly 138 such that the reductant supply
passageway 132 supplies reductant from the local tank 114 to the
dosing pump assembly 138. The reductant supply passageway 132
extends between the local tank 114 and the dosing pump assembly
138, and in at least some embodiments, the reductant supply
passageway 132 can extend from the reductant supply port 124 of the
local tank 114 to a suction side 138a of the dosing pump assembly
138. Further, in at least some embodiments, the reductant supply
passageway 132 can extend through the reductant supply port 124 on
the tank manifold 120 into the local tank 114, and terminate at a
bottom portion of the local tank cavity 116.
[0021] The dosing pump assembly 138 of each reductant dosing
assembly 102, 102' pumps the reductant from the local tank 114 in a
first direction that extends from the local tank 114 to the
reductant injection assembly 104. The dosing pump assembly 138 has
an inlet or suction side 138a and an outlet or discharge side 138b.
The suction side 138a is fluidly coupled to the local tank 114, and
the discharge side 13b is configured to fluidly couple to the
reductant injection assembly 104. Further, the dosing pump assembly
138 includes a pump 140 and first and second check valves 142 and
144 in fluid communication with the pump 140, although in
alternative embodiments, one or both of the first and second check
valves 142 and 144 can be omitted. Each of the first and second
check valves 142 and 144 permits flow of reductant in the first
direction and limits or prevents flow of the reductant in a second
direction, opposite the first direction. The first check valve 142
is fluidly coupled to the pump 140 at the suction side 138a of the
dosing pump assembly 138, between the local tank 114 and the pump
140, so as to limit or prevent flow of the reductant in the second
direction from the pump 140 back toward the local tank 114. The
second check valve 144 is connected to the pump 140 at the
discharge side 138b of the dosing pump assembly 138, between the
pump 140 and the reductant injection assembly 104, so as to limit
or prevent flow of the reductant in the second direction from the
reductant injection assembly 104 back toward the pump 140.
[0022] The reductant discharge passageway 162 of each reductant
dosing assembly 102, 102', and 102'' extends from the discharge
side 138b of the dosing pump assembly 138 to a terminal end of the
reductant discharge passageway 162 that includes or terminates at
the port 164. The port 164 can include a coupling configured to
removably connect the reductant dosing assembly 102, 102', and
102'' to the reductant injection assembly 104. Thus, when the
reductant dosing assembly 102, 102', and 102'' is connected to the
reductant injection assembly 104, the reductant discharge
passageway 162 supplies reductant in the first direction to the
reductant injection assembly 104. The reductant injection assembly
104 includes an injector 186 and can include a reductant passageway
184 that is removably connectable to the port 164 so as to place
the injector 186 in fluid communication with the port 164, the
reductant discharge passageway 162, and the reductant dosing
assembly 102, 102', and 102''.
[0023] In addition to reductant, compressed gas can also be
supplied to the reductant injection assembly 104, where the
injector 186 can combine the reductant and compressed gas into a
mixture and inject the mixture into the engine exhaust stream.
Thus, each reductant dosing assembly 102, 102', and 102'' can
include a compressed gas passageway 172 that fluidly couples the
compressed gas assembly 106 to the reductant injection assembly
104. In this embodiment, the compressed gas passageway 172 extends
from the port 170 to the port 178 and is defined by, or otherwise
supported by, a compressed gas manifold 180 that can be mounted to
the at least one wall 112 of the reductant dosing cabinet 110.
Thus, the compressed gas passageway 172 can be said to extend to
terminate ends of the compressed gas passageway 172 that terminate
at or include the ports 170 and 178. Further, the compressed gas
passageway 172 includes a gas regulator 174 that regulates the
pressure of the compressed gas, and a shutoff valve 176, both of
which are situated between the ports 170 and 178. However, in
alternative embodiments, one or both of the gas regulator 174 and
shutoff valve 176 can be omitted or moved to the compressed gas
assembly 106 or the reductant injection assembly 104.
[0024] The port 170 can include a coupler that removably connects
the compressed gas passageway 172 to the compressed gas assembly
106 so as to place the compressed gas assembly 106 in fluid
communication with the compressed gas passageway 172. The
compressed gas assembly 106 includes a compressed gas source 190
such as a compressor that pressurizes a gas, and can include a
compressed gas passageway 188 that is removably connectable to the
port 170. Thus, the compressed gas passageway 188 extends from the
compressed gas source 190 to the port 170 so as to supply the
compressed gas from the compressed gas source 190 to the reductant
dosing assembly 102, 102', and 102''.
[0025] Similarly, the port 178 can include a coupler that removably
connects the compressed gas passageway 172 to the reductant
injection assembly 104 so as to place the reductant injection
assembly 104 in fluid communication with the compressed gas
passageway 172. The reductant injection assembly 104 can include a
compressed gas passageway 182 that is removably connectable to the
port 178 and that extends from the port 178 to the injector 186 so
as to supply the compressed gas from the reductant dosing assembly
102, 102', and 102'' to the injector 186.
[0026] As the reductant from the local tank 114 depletes in each
reductant dosing assembly 102, 102', and 102'', the reductant in
the local tank 114 can be replenished by the reductant
replenishment assembly 108. Thus, each reductant dosing assembly
102, 102', and 102'' can include a reductant replenishment
passageway 146 that is configured to fluidly couple the reductant
replenishment assembly 108 to the local tank 114 so as to replenish
the reductant in the local tank 114. As shown, the reductant
replenishment assembly 108 is spaced from, and external to, the
reductant dosing cabinet 110.
[0027] In the embodiments of FIGS. 1 to 3, the reductant
replenishment passageway 146 extends from the port 150 to the
reductant replenishment inlet port 126 of the local tank 114 and
includes a shutoff valve 148. Thus, the reductant replenishment
passageway 146 can be said to extend from the local tank 114 to a
terminal end of the reductant replenishment passageway 146 that
includes or terminates at the port 150. One or more of the port
150, the port 164, the reductant replenishment passageway 146, and
the dosing pump assembly 138 can be defined by, or otherwise
supported by, a reductant manifold 158 that can be mounted to the
at least one wall 112 of the reductant dosing cabinet 110. The
reductant manifold 158 can also include a heater 152 to prevent
freezing of any reductant in the manifold.
[0028] The port 150 can include a coupler that removably connects
the reductant replenishment assembly 108 to the reductant
replenishment passageway 146. The reductant replenishment assembly
108 includes a remote tank 192, a reductant passageway 194, and a
replenishment pump 196. The remote tank 192 is spaced from the
reductant dosing assembly 102, 102', and 102'' and defines a cavity
having a maximum volume that is configured to hold the reductant
therein, wherein the maximum volume of the remote tank 192 is
greater than the maximum volume of the local tank 114 and can
further be greater than a maximum volume of the cavity 113 of the
reductant dosing cabinet 110. The reductant passageway 194 is
removably connectable to the port 150, and extends from the remote
tank 192 to the port 150. The replenishment pump 196, which is
connected to or is a part of the reductant passageway 194, pumps
the reductant from the remote tank 192 to the reductant dosing
assembly 102, 102', and 102'' via the reductant passageway 194 so
as to replenish or refill the local tank 114.
[0029] When the environmental temperature surrounding each
reductant dosing assembly 102, 102', and 102'' drops below the
freezing temperature of the reductant, any reductant remaining in
the reductant dosing assembly 102, 102', and 102'' can freeze.
Freezing of the reductant can inhibit the reductant dosing assembly
102, 102', and 102'' from providing reductant to the reductant
injection assembly 104 and can even result in the cracking of
various components of the reductant dosing assembly 102, 102', and
102'' such as the pump assembly 138. Therefore, to reduce the
likelihood of freezing, each reductant dosing assembly 102, 102',
and 102'' also includes reductant purge componentry that is
configured to purge various components of the reductant dosing
assembly 102, 102', and 102'.
[0030] Referring specifically to FIG. 1, the reductant purge
componentry of the reductant dosing assembly 102 includes a
reductant return passageway 154 and a purge passageway 134. The
reductant return passageway 154, which can be defined by or
otherwise supported by the reductant manifold 158, extends from the
reductant discharge passageway 162 at a location that is between
the dosing pump assembly 138 and the port 164, and extends to the
reductant replenishment passageway 146 at a location that is
between the local tank 114 and the port 150. The reductant return
passageway 154 includes a shutoff valve 156 that selectively
permits and inhibits flow of the reductant from the reductant
discharge passageway 162 to the reductant replenishment passageway
146.
[0031] The purge passageway 134, which can be defined by or
otherwise supported by the tank manifold 120, extends from the
reductant supply passageway 132 between an inlet of the reductant
supply passageway 132 and the dosing pump assembly 138, and extends
to an ambient air source such as the environment adjacent the purge
passageway 134. In at least some embodiments, the purge passageway
134 can extend from the reductant supply passageway 132 between the
local tank 114 and the dosing pump assembly 138. The purge
passageway 134 includes a shutoff valve 136 that selectively
permits and inhibits flow of ambient air from the environment to
the reductant supply passageway 132. Thus, the purge passageway 134
is configured to selectively couple the pump assembly 138 to the
ambient air source during a purging operation such that the pump
assembly 138 draws air from the ambient air source through the
reductant supply passageway 132 and the pump assembly 138 during
the purging operation to purge the reductant supply passageway 132
and the pump assembly 138. As will be understood, the purge
passageway 134 can include alternative componentry such as a
three-way valve at the junction of the reductant supply passageway
132 and the purge passageway 134.
[0032] Before operating the reductant dosing cabinet 110, the
reductant dosing cabinet 110 is coupled to at least one, such as
all, of the reductant injection assembly 104, the compressed gas
assembly 106, and the reductant replenishment assembly 108. During
dosing operations, the local tank 114 and compressed gas assembly
106 are fluidly coupled to the reductant injection assembly 104. In
particular, the shutoff valve 176 is in an open position such that
compressed gas flows through the shutoff valve 176 to the injector
186, and the shutoff valve 148 can be in an open position so that
reductant can be pumped from the remote tank 192 to the local tank
114 as the reductant in the local tank 114 depletes. Further, the
shutoff valve 156 can be in a closed position so as to prevent
reductant from returning to the local tank 114, and the shutoff
valve 136 can be in a closed position so as to prevent ambient air
from being drawn into the reductant supply passageway 132 via the
purge passageway 134.
[0033] During purging operations, residual reductant in the
reductant dosing assembly 102 can be purged in two stages. In one
stage, which can be for example the first stage, the reductant
discharge passageway 162 is fluidly coupled to the local tank 114
via the reductant return passageway 154. In particular, the shutoff
valves 148 and 136 are in closed positions, the shutoff valves 176
and 156 are in open positions, and the pump 140 is turned off.
Compressed gas from the compressed gas source 190 flows through the
compressed gas passageway 172 to the reductant injection assembly
104, and some or all of the compressed gas flows back into the
reductant discharge passageway 162 toward the pump assembly 140 in
a second direction, opposite the first direction. As the compressed
gas flows into the reductant discharge passageway 162, the
compressed gas forces the reductant out of the reductant discharge
passageway 162 and back to the local tank 114 via the reductant
return passageway 154, thereby leaving the reductant discharge
passageway 162 substantially devoid of residual reductant.
[0034] In the other stage, which can be for example the second
stage, the shutoff valves 148 and 176 are in closed positions, the
pump assembly 138 is fluidly connected to the ambient air source.
In particular, the shutoff valves 136 and 156 are in open
positions, and the pump 140 is turned on. The pump 140 draws
ambient air through the purge passageway 134, through the reductant
supply passageway 132 and the pump assembly 138, and forces the
ambient air out the discharge side 138b of the pump assembly 138
back to the local tank 114 via the reductant return passageway 154.
As the ambient air flows through the reductant supply passageway
132, the pump assembly 138, and the reductant return passageway
154, the ambient air forces the reductant out of the reductant
supply passageway 132, the pump assembly 138, and the reductant
return passageway 154 and back to the local tank 114, thereby
leaving the reductant supply passageway 132, the pump assembly 138,
and the reductant return passageway 154 substantially devoid of
residual reductant.
[0035] Referring now to FIG. 2, the reductant purge componentry of
the reductant dosing assembly 102' includes a reductant return
passageway 154 as described above in relation to FIG. 1, and a
purge passageway 200. The purge passageway 200 extends from the
compressed gas passageway 172 between the port 170 and the port
178, and extends to the reductant supply passageway 132 between an
inlet of the reductant supply passageway 132 and the pump assembly
138. In at least some embodiments, the purge passageway 200 can
extend from the reductant supply passageway 132 between the local
tank 114 and the dosing pump assembly 138. The purge passageway 200
includes a shutoff valve 202 that selectively permits and inhibits
flow of the compressed gas from the compressed gas assembly 106 to
the reductant supply passageway 132. As will be understood, the
purge passageway 200 can include alternative componentry such as a
three-way valve at the junction of the compressed gas passageway
172 and the purge passageway 200.
[0036] Before operating the reductant dosing cabinet 110, the
reductant dosing cabinet 110 is coupled to at least one, such as
all, of the reductant injection assembly 104, the compressed gas
assembly 106, and the reductant replenishment assembly 108. During
dosing operations, the shutoff valve 176 is in an open position and
the shutoff valve 202 is in a closed position such that compressed
gas flows through the shutoff valve 176 to the injector 186. The
shutoff valve 148 can be in an open position so that reductant can
be pumped from the remote tank 192 to the local tank 114 as the
reductant in the local tank 114 depletes. Further, the shutoff
valve 156 can be in a closed position so as to prevent reductant
from returning to the local tank 114.
[0037] During purging operations, residual reductant in the
reductant dosing assembly 102 can be purged in two stages. In one
stage, which can be for example the first stage, the reductant
discharge passageway 162 is fluidly coupled to the local tank 114
via the reductant return passageway 154. In particular, the shutoff
valves 148 and 202 are in closed positions, the shutoff valves 176
and 156 are in open positions, and the pump 140 is turned off.
Compressed gas from the compressed gas source 190 flows through the
compressed gas passageway 172 to the reductant injection assembly
104, and some or all of the compressed gas flows back into the
reductant discharge passageway 162 toward the pump assembly 140 in
a second direction, opposite the first direction. As the compressed
gas flows into the reductant discharge passageway 162, the
compressed gas forces the reductant out of the reductant discharge
passageway 162 and back to the local tank 114 via the reductant
return passageway 154, thereby leaving the reductant discharge
passageway 162 substantially devoid of residual reductant.
[0038] In the other stage, which can be for example the second
stage, the shutoff valves 148 and 176 are in closed positions, the
shutoff valves 156 and 202 are in open positions. Further, the pump
140 is turned off, although in alternative embodiments, the pump
140 can be left on. The compressed gas flows through the purge
passageway 200, through the reductant supply passageway 132 and the
pump assembly 138, and out the discharge side 138b of the pump
assembly 138 back to the local tank 114 via the reductant return
passageway 154. As the compressed gas flows through the reductant
supply passageway 132, the pump assembly 138, and the reductant
return passageway 154, the compressed gas forces the reductant out
of the reductant supply passageway 132, the pump assembly 138, and
the reductant return passageway 154 and back to the local tank 114,
thereby leaving the reductant supply passageway 132, the pump
assembly 138, and the reductant return passageway 154 substantially
devoid of residual reductant.
[0039] Referring now to FIG. 3, the reductant purge componentry of
the reductant dosing assembly 102'' includes a reductant return
passageway 154 as described above in relation to FIG. 1, and a
purge passageway 300. The purge passageway 300 is configured to
selectively couple the discharge side 138b of the pump assembly 138
to the reductant replenishment assembly 108 during a purge
operation so as to return the reductant from both the local tank
114 and the pump assembly 138 to the reductant replenishment
assembly 108 during the purge operation. The purge passageway 300
extends from the reductant discharge passageway 162 between the
pump assembly 138 and the port 164, and extends to a port 306. The
port 306 provides a passageway through the at least one wall 112 of
the reductant dosing cabinet 110 from an interior of the reductant
dosing cabinet 110 to an exterior of the reductant dosing cabinet
110. The port 306 may be supported by, or otherwise mounted to, at
least one of the interior surface 112a of the reductant dosing
cabinet 110, the exterior surface 112b, and an inner surface of the
at least one wall 112 that extends between the internal and
exterior surfaces 112a and 112b and defines an opening through the
at least one wall 112. Further, the port 306 can include a coupling
that is configured so as to enable the reductant dosing assembly
102'' to be removably connectable to, and placed in fluid
communication with the reductant replenishment assembly 108.
[0040] The purge passageway 300 is coupled to the reductant
discharge passageway 162 at a junction 302 between the pump
assembly 138 and the port 164. The junction 302 includes a diverter
valve 304 that is coupled to both the reductant discharge
passageway 162 and the purge passageway 300. The diverter valve 304
is selectively configurable to operate in a first or pass-through
position that permits flow of the reductant to the reductant
injection assembly 104, while inhibiting flow of the reductant to
the purge passageway 300, and a second or diverting position that
permits flow of the reductant to the purge passageway 300, while
inhibiting flow of the reductant to the reductant injection
assembly 104. As will be understood, the purge componentry can
include devices other than the diverter valve 304 such as a first
shutoff valve coupled to the reductant discharge passageway 162
between the junction 302 and the port 164, and a second shutoff
valve coupled to the purge passageway 300 between the junction 302
and the port 306.
[0041] Before operating the reductant dosing cabinet 110, the
reductant dosing cabinet 110 is coupled to at least one, such as
all, of the reductant injection assembly 104, the compressed gas
assembly 106, and the reductant replenishment assembly 108. During
dosing operations, the shutoff valve 176 is in an open position
such that compressed gas flows through the shutoff valve 176 to the
reductant injection assembly 104, and the diverter valve 304 is in
the pass-through position so as to permit flow of the reductant to
the reductant injection assembly 104. The shutoff valve 148 can be
in an open position so that reductant can be pumped from the remote
tank 192 to the local tank 114 as the reductant in the local tank
114 depletes. Further, the shutoff valve 156 can be in a closed
position so as to prevent reductant from returning to the local
tank 114.
[0042] During purging operations, residual reductant in the
reductant dosing assembly 102'' can be purged in two or more
stages. In one stage, which can be for example the first stage, the
reductant discharge passageway 162 is fluidly coupled to the local
tank 114 via the reductant return passageway 154. In particular,
the shutoff valve 148 is in a closed position, the diverter valve
304 is in the pass-through position, the shutoff valves 156 and 176
are in open positions, and the pump 140 is turned off. Compressed
gas from the compressed gas source 190 flows through the compressed
gas passageway 172 to the reductant injection assembly 104, and
some or all of the compressed gas flows back into the reductant
discharge passageway 162 toward the pump assembly 140 in a second
direction, opposite the first direction. As the compressed gas
flows into the reductant discharge passageway 162, the compressed
gas forces the reductant out of the reductant discharge passageway
162 and back to the local tank 114 via the reductant return
passageway 154, thereby leaving the reductant discharge passageway
162 substantially devoid of residual reductant.
[0043] In another stage, which can be for example the second stage,
the discharge side 138b of the pump assembly 138 is fluidly coupled
to the reductant replenishment assembly 108. In particular, the
shutoff valves 148 and 176 are in closed positions, the diverter
valve 304 is the diverting position, and the shutoff valves 156 is
in an open position. Further, the pump 140 is operated such that
the reductant in the local tank 114 is drawn through the reductant
supply passageway 132 and the pump assembly 138, and is forced out
the discharge side 138b of the pump assembly 138 back to the remote
tank 192 via the purge passageway 300. As the local tank 114
empties, ambient air flows into the local tank 114 through the vent
118 to fill the space in the local tank cavity 116 of the local
tank 114 that was previously occupied by the reductant.
[0044] When most, if not all, of the reductant is purged from the
local tank 114, the pump 140 draws the ambient air in the local
tank 114 through the reductant supply passageway 132 and the pump
assembly 138, and forces the ambient air out of the discharge side
138b of the pump assembly 138 to the remote tank 192 via the purge
passageway 300. As the ambient air flows through the reductant
supply passageway 132, the pump assembly 138, the reductant return
passageway 154, and the purge passageway 300, the ambient air
forces the reductant out of the reductant supply passageway 132,
the pump assembly 138, the reductant return passageway 154, and the
purge passageway 300, thereby leaving the local tank 114, the
reductant supply passageway 132, the pump assembly 138, the
reductant return passageway 154, and the purge passageway 300
substantially devoid of reductant. Thus, the entire reductant
dosing assembly 102'', including the local tank 114, can be
substantially purged of reductant. In at least some embodiments,
the first stage of the purge operation can be repeated to further
ensure that the entire reductant dosing assembly 102'' is
substantially purged of reductant.
INDUSTRIAL APPLICABILITY
[0045] Referring to FIG. 4, a simplified schematic diagram of an
off-vehicle engine system 400 according to one embodiment is shown
that can implement any of the reductant dosing assemblies 102,
102', and 102'' of FIGS. 1 to 3. The engine system 400 has an
engine 402 and an exhaust treatment system. The engine 402 may be,
for example, a diesel engine that generates an exhaust stream
including gaseous pollutants and solid particulate matter such as
soot. The engine 402 has an exhaust outlet, which provides the
exhaust stream to the exhaust treatment system. The exhaust
treatment system can include various modules that operate to reduce
the pollutants in the exhaust stream such as (without limitation)
one or more of a diesel oxidation catalyst (DOC) module 404, a
diesel particulate filter (DPF) module 406, and a selective
catalytic reduction (SCR) module 408.
[0046] During operation of the engine 402, the exhaust stream flows
from the exhaust outlet of the engine 402 to the DOC module 404,
which may include an oxidation catalyst. The oxidation catalyst
converts the nitrogen monoxide (NO) components in the exhaust
stream to nitrogen dioxide (NO.sub.2) as the exhaust stream passes
from the inlet of the DOC module 404 to the outlet of the DOC
module 404. The exhaust stream with the converted NO2 flows from
the DOC module 404 to the DPF module 406. The DPF module 406 may
trap solid particulate matter such as soot, while allowing the
gaseous components of the exhaust stream to pass to the outlet of
the DPF module 406. The gaseous components of the exhaust stream
output from the DPF module 406 are combined with a mixture of
reductant and air, which is injected into the exhaust stream by the
reductant supply system 100, 100', and 100'', which includes the
reductant injection assembly 104. The exhaust stream with reductant
flows to the SCR module 408, which includes an SCR catalyst. The
SCR catalyst promotes a reaction between the reductant and nitrogen
oxides (NO.sub.x) in the exhaust stream to form diatomic nitrogen
(N.sub.2) and water (H.sub.2O).
[0047] The reductant injection assembly 104 works in tandem with
the reductant dosing assembly 102, 102', and 102'', the compressed
gas assembly 106, and the reductant replenishment assembly 108
during operation of the engine 402 to supply the mixture of
reductant and air. As described above, the reductant dosing
assembly 102, 102', and 102'' provides compressed gas from the
compressed gas assembly 106 to the reductant injection assembly 104
via compressed gas passageway 182 and reductant from the local tank
114 (see FIGS. 1 to 3) to the reductant injection assembly 104 via
reductant passageway 184. As the reductant in the local tank 114
depletes, the reductant replenishment assembly 108 supplies the
reductant to the local tank 114 of the reductant dosing assembly
102, 102', and 102'' via the reductant replenishment passageway
146.
[0048] When the environmental temperature surrounding each
reductant dosing assembly 102, 102', and 102'' drops below the
freezing temperature of the reductant, the reductant dosing
assembly 102, 102', and 102'' performs a purging operation, whereby
reductant in the reductant passageways of the reductant dosing
assembly 102, 102', and 102'' is purged to either the local tank
114 of the reductant dosing assembly 102, 102', and 102'' as
described above in relation to FIGS. 1 and 2, or to the reductant
replenishment assembly 108 via reductant purge passageway 308 as
described above in relation to FIG. 3.
[0049] It will be appreciated by those skilled in the art that
changes could be made to the embodiments described above without
departing from the broad inventive concept thereof. Furthermore, it
should be appreciated that the structure, features, and methods as
described above with respect to any of the embodiments described
herein can be incorporated into any of the other embodiments
described herein unless otherwise indicated. It is understood,
therefore, that this invention is not limited to the particular
embodiments disclosed, but it is intended to cover modifications
within the spirit and scope of the present disclosure.
* * * * *