U.S. patent application number 14/492694 was filed with the patent office on 2016-03-24 for catalyst protection against hydrocarbon exposure.
This patent application is currently assigned to Caterpillar Inc.. The applicant listed for this patent is Caterpillar Inc.. Invention is credited to Brandon Abel, Aaron Harmon, Adwait Joshi, Joshua Ratts, Wilce Williams.
Application Number | 20160084135 14/492694 |
Document ID | / |
Family ID | 55525326 |
Filed Date | 2016-03-24 |
United States Patent
Application |
20160084135 |
Kind Code |
A1 |
Harmon; Aaron ; et
al. |
March 24, 2016 |
Catalyst Protection Against Hydrocarbon Exposure
Abstract
A system to protect an after treatment system from the effects
of hydrocarbon accumulation on a catalyst. An engine system
microprocessor using software estimates the amount of hydrocarbon
accumulation on the after treatment system based on engine system
parameters and other parameters. The accumulated hydrocarbons can
cause an exothermic event if the catalyst temperature is allowed to
ramp up too quickly. Similarly, accumulated hydrocarbon can
temporarily reduce after treatment system performance. In the case
of SCR, the microprocessor can control a reductant injector to
modulate the amount of reductant being injected into the after
treatment system to control the amount of ammonia slip.
Alternatively or in addition to, the microprocessor can communicate
with proper electronic control modules to modulate the engine
system parameters such as engine speed, fuel, and back pressure to
control engine exhaust flow temperature during operation of the
engine system.
Inventors: |
Harmon; Aaron; (Dunlap,
IL) ; Ratts; Joshua; (East Peoria, IL) ;
Williams; Wilce; (Peoria, IL) ; Joshi; Adwait;
(Dunlap, IL) ; Abel; Brandon; (Peoria,
IL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Caterpillar Inc. |
Peoria |
IL |
US |
|
|
Assignee: |
Caterpillar Inc.
Peoria
IL
|
Family ID: |
55525326 |
Appl. No.: |
14/492694 |
Filed: |
September 22, 2014 |
Current U.S.
Class: |
701/102 |
Current CPC
Class: |
F01N 2610/02 20130101;
F01N 2590/08 20130101; F01N 13/009 20140601; Y02T 10/24 20130101;
F02D 2200/021 20130101; F02D 2200/0802 20130101; F02D 2200/0404
20130101; F02D 41/1459 20130101; F02D 41/064 20130101; F02D 41/025
20130101; Y02T 10/47 20130101; F01N 2900/0412 20130101; F01N
13/0097 20140603; Y02T 10/40 20130101; F02D 41/068 20130101; F01N
2900/0416 20130101; F01N 3/208 20130101; F01N 2900/1616 20130101;
F01N 2900/1402 20130101; F01N 9/005 20130101; F01N 3/103 20130101;
F01N 13/017 20140601; F01N 2900/1602 20130101; F01N 2900/1618
20130101; F01N 2900/1621 20130101; F02D 41/0235 20130101; Y02A
50/2325 20180101; Y02T 10/26 20130101; F01N 13/011 20140603; F01N
3/2066 20130101; Y02T 10/12 20130101 |
International
Class: |
F01N 9/00 20060101
F01N009/00; F01N 3/20 20060101 F01N003/20 |
Claims
1. A method of protecting an after treatment system from effects of
hydrocarbon accumulation, comprising the steps of: receiving, at a
microprocessor of an engine system, engine system parameters from a
plurality of electronic control modules of the engine system;
estimating, with the microprocessor of the engine system, an amount
of engine out hydrocarbon based on the engine system parameters;
receiving, from a memory, a correction factor that adjusts the
estimated amount of engine out hydrocarbon; estimating, with the
microprocessor of the engine system, a hydrocarbon mass on the
after treatment system of the engine system with the adjusted
estimated amount of engine out hydrocarbon; and modulating, with
the microprocessor of the engine system, a reductant that is
applied to the after treatment system of the engine system based on
the estimated hydrocarbon mass.
2. The method of protecting of claim 1 further comprising the step
of controlling a gradual engine ramp up, with the microprocessor of
the engine system that is communicating with a first electronic
control module of the plurality of electronic control modules,
based on the estimated hydrocarbon mass.
3. The method of protecting of claim 2 further comprising
preventing an exothermic event in the after treatment system by
controlling the gradual engine ramp up.
4. The method of protecting of claim 1, wherein the correction
factor is a manifold correction factor.
5. The method of protecting claim 1, wherein the engine system
parameters are selected from an amount of fuel, an engine speed, an
engine timing, a total mass exhaust flow, a crank mode, an
injection amount, an inlet manifold pressure, an inlet manifold
temperature, a coolant temperature, an ambient temperature and an
ambient pressure.
6. The method of protecting of claim 1, wherein the estimated
amount of engine out hydrocarbon includes a mass rate for engine
hydrocarbon at startup or various engine hydrocarbon run mode.
7. The method of protecting of claim 1, wherein the microprocessor
communicates with a reductant injector to modulate the applied
reductant.
8. The method of protecting of claim 2 further comprising the step
of receiving, with the microprocessor, sensor information from a
sensor.
9. The method of protecting of claim 8, wherein the sensor is a
throttle position sensor.
10. The method of protecting of claim 9, wherein the step of
controlling the gradual engine ramp up allows the engine to
gradually warm up regardless of a position of a throttle sensed by
the throttle position sensor.
11. The method of protecting of claim 1, wherein the step of
controlling engine ramp up includes controlling an amount of fuel
being injected into the engine.
12. A method of protecting an after treatment system from effects
of hydrocarbon accumulation, comprising the steps of: receiving, at
a microprocessor of an engine system, engine system parameters from
a plurality of electronic control modules of the engine system;
estimating, with the microprocessor of the engine system, an amount
of engine out hydrocarbon based on the engine system parameters;
receiving, from a memory, a correction factor that adjusts the
estimated amount of engine out hydrocarbon; estimating, with the
microprocessor of the engine system, a hydrocarbon mass on the
after treatment system of the engine system with the adjusted
estimated amount of engine out hydrocarbon; and controlling gradual
exhaust temperature ramp up, with the microprocessor of the engine
system that is communicating with a first electronic control module
of the plurality of electronic control modules, based on the
estimated hydrocarbon mass.
13. The method of protecting of claim 12 further comprising
modulating, with the microprocessor of the engine system
communicating with a reductant injector, a reductant that is
applied to the after treatment system of the engine system.
14. The method of protecting of claim 12 further comprising
preventing an exothermic event in the after treatment system by
controlling step.
15. The method of protecting of claim 12, wherein the correction
factor is a manifold correction factor.
16. The method of protecting of claim 12, wherein the estimated
amount of engine out hydrocarbon includes a mass rate for engine
hydrocarbon at startup or various engine hydrocarbon run mode.
17. The method of protecting of claim 12 further comprising the
step of receiving, with the microprocessor of the engine system,
sensor information from a throttle position sensor.
18. The method of protecting of claim 17, wherein the step of
controlling the gradual engine ramp up allows the engine to
gradually warm up regardless of a position of a throttle sensed by
the throttle position sensor.
19. A system that protects an after treatment system of a vehicle
from the effects of hydrocarbon accumulation, comprising: means for
processing that communicates with a hydrocarbon estimation software
stored on means for storing of an engine system computer; means for
injecting configured to inject a reductant into the after treatment
system; and means for interfacing that allows the means for
processing to communicate with the means for injecting, wherein the
means for processing executes the hydrocarbon estimation software
to perform the steps of: receiving, at the means for processing,
engine system parameters from a plurality of electronic control
modules of the engine systems; estimating, with the means for
processing, an amount of engine out hydrocarbon based on the engine
system parameters; receiving, from the means for storing, a
correction factor that adjusts the estimated amount of engine out
hydrocarbon; estimating, with the means for processing, a
hydrocarbon mass on the after treatment system of the engine system
with the adjusted estimated amount of engine out hydrocarbon; and
modulating, with the means for processing controlling the means for
injecting, the reductant that is applied to the after treatment
system of the engine system.
20. The system of claim 19, wherein the estimated amount of engine
out hydrocarbon includes a mass rate for engine hydrocarbon at
startup or various engine hydrocarbon run mode.
Description
TECHNICAL FIELD
[0001] The disclosure relates generally to protecting after
treatment systems in an engine system (Marine, Locomotive, Electric
Power, Machine, etc.), and more particularly, to protecting the
after treatment systems due to accumulation of hydrocarbon on
catalysts.
BACKGROUND
[0002] Engines such as diesel or other lean burning engines
generally provide more complete fuel combustion and better fuel
efficiency but require higher operating pressures and temperatures
compared to non-lean burning engines. With the higher pressures and
temperatures, oxides of nitrogen (NO.sub.x) emissions including
nitric oxide (NO) and nitrogen dioxide (NO.sub.2) are typically
higher as oxygen and nitrogen tend to combine more easily at higher
temperatures. NO.sub.x emissions cause a number of environmental
issues such as smog, acid rain, excess aqueous nutrients and so on.
Thus, emissions control regulations limit the amount of NO.sub.x
emissions of engines and necessitate the use of reduction devices
in the exhaust systems in order to reduce the NO.sub.x emissions to
an acceptable level.
[0003] An after treatment system, such as a selective catalytic
reduction (SCR) device is typically used to control the NO.sub.x
emissions of engines. The catalyst converts NO.sub.x gases into
nitrogen gases and water with the aid of a reducing agent. The
reducing agent typically contains hydrogen or the like, which is
capable of removing oxygen from NO.sub.x gases. Commonly used
reducing agents are ammonia, Diesel Exhaust Fluid (DEF), urea,
hydrocarbon-containing compounds and the like. The introduction of
the reducing agent to the after treatment system allows for it to
be adsorbed onto the catalyst to facilitate the reduction process.
Typically, a solution of the reducing agent is internally or
externally carried by an engine, and a supplying system injects the
reducing agent into the exhaust gas stream entering the SCR
system.
[0004] During engine operations, the unburned hydrocarbons in the
exhaust stream enters the SCR system and can adsorb onto the
catalyst. The hydrocarbons can be in liquid phase or can condense
into the liquid phase upon contacting the catalyst surface. Once in
the liquid phase, the hydrocarbons can adsorb and accumulate on the
catalyst pores and void volumes. Rapid heating of the catalyst
after prolonged idle or low temperature operations suitable for
accumulation of hydrocarbons can ignite the hydrocarbons and cause
an exothermic event that could potentially damage the catalyst.
Alternatively, if the accumulated hydrocarbons don't ignite, they
can inhibit the catalyst performance by blocking the active
catalyst sites used for oxidation of hydrocarbons and carbon
monoxide (diesel oxidation catalyst) and conversion of NO.sub.x
gases into nitrogen gases and water (selective catalytic
reduction).
[0005] A system for coordinated engine and emissions control is
described in U.S. Pat. App. No. 2013/0067894 (the '894 application)
published on Mar. 21, 2013. The '894 application discloses a
selective catalytic reduction control system that may incorporate a
diesel engine or a model of the engine, a selective catalytic
reduction exhaust after-treatment mechanism for connection to the
engine, an engine controller, and a selective catalytic reduction
controller connected to the selective catalytic reduction exhaust
after treatment mechanism and to the engine controller. The engine
controller and the selective catalytic reduction controller may
provide coordinated control of the engine and selective catalytic
reduction exhaust after-treatment mechanism to control an amount of
pollutants in an exhaust emission from the engine. However, this
system does not determine based on engine parameter inputs, the
amount of hydrocarbons accumulation on the catalyst. The amount of
hydrocarbon accumulation affects the efficiency of the catalyst in
the SCR system and has the potential for an undesired exothermic
event. Without determining the amount of hydrocarbon accumulation,
the inlet temperature cannot be properly controlled to prevent the
exothermic event and the reducing agent dosing cannot be properly
modulated in order to not exceed ammonia slip targets.
[0006] Accordingly, there is a need for a system that efficiently
utilizes an after treatment system that includes SCR to minimizes
NH.sub.3 slip past the catalyst and/or prevents exothermic events
due to accumulation of hydrocarbons on the catalyst.
SUMMARY
[0007] In one aspect, the disclosure is directed to a method for
protecting an after treatment system from effects of hydrocarbon
accumulation, the steps include receiving, at a microprocessor of
an engine system, engine system parameters from a plurality of
electronic control modules of the engine system, estimating, with
the microprocessor of the engine system, an amount of engine out
hydrocarbon based on the engine system parameters, receiving, from
a memory, a correction factor that adjusts the estimated amount of
engine out hydrocarbon, estimating, with the microprocessor of the
engine system, a hydrocarbon mass on the after treatment system of
the engine system with the adjusted estimated amount of engine out
hydrocarbon, and modulating, with the microprocessor of the engine
system, a reductant that is applied to the after treatment system
of the engine system based on the estimated hydrocarbon mass.
[0008] In another aspect, a method of protecting an after treatment
system from effects of hydrocarbon accumulation is disclosed and
includes the steps of receiving, at a microprocessor of an engine
system, engine system parameters from a plurality of electronic
control modules of the engine system, estimating, with the
microprocessor of the engine system, an amount of engine out
hydrocarbon based on the engine system parameters, receiving, from
a memory, a correction factor that adjusts the estimated amount of
engine out hydrocarbon, estimating, with the microprocessor of the
engine system, a hydrocarbon mass on the after treatment system of
the engine system with the adjusted estimated amount of engine out
hydrocarbon, and controlling gradual exhaust temperature ramp up,
with the microprocessor of the engine system that is communicating
with a first electronic control module of the plurality of
electronic control modules, based on the estimated hydrocarbon
mass.
[0009] In still another aspect, a system that protects an after
treatment system of a vehicle from the effects of hydrocarbon
accumulation that includes means for processing that communicates
with a hydrocarbon estimation software stored on means for storing
of an engine system computer, means for injecting configured to
inject a reductant into the after treatment system, and means for
interfacing that allows the means for processing to communicate
with the means for injecting, wherein the means for processing
executes the hydrocarbon estimation software to perform the steps
of: receiving, at the means for processing, engine system
parameters from a plurality of electronic control modules of the
engine systems, estimating, with the means for processing, an
amount of engine out hydrocarbon based on the engine system
parameters, receiving, from the means for storing, a correction
factor that adjusts the estimated amount of engine out hydrocarbon,
estimating, with the means for processing, a hydrocarbon mass on
the after treatment system of the engine system with the adjusted
estimated amount of engine out hydrocarbon, and modulating, with
the means for processing controlling the means for injecting, the
reductant that is applied to the after treatment system of the
engine system.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is an illustration of an exemplary vehicle that
utilizes an after treatment process according to the
disclosure.
[0011] FIG. 2 is a perspective view of the after treatment system
with the top removed to illustrate the components, and exhaust flow
according to the disclosure.
[0012] FIG. 3 is a flow diagram of a method of protecting against
hydrocarbon damage to the after treatment system according to the
disclosure.
[0013] FIG. 4 illustrates components of an engine system computer
according to the disclosure.
[0014] FIG. 5 is a diagram of steps to protect the after treatment
from the effects of hydrocarbon accumulation according to the
disclosure.
DETAILED DESCRIPTION
[0015] The disclosure sets forth a process and system to compensate
for hydrocarbon accumulation in after treatment systems. The
process and system set forth in the disclosure estimate or
calculate the amount of hydrocarbon that is expected to accumulate
on the after treatment system, such as the SCR and then proceeds to
control the engine to gradually ramp-up the temperature in order to
prevent the exothermic reaction that could damage the catalyst. In
addition to or alternatively, the process and system can modulate
the amount of reductant being added to the after treatment system
in order to optimize the SCR catalyst performance based on the
estimated or calculated hydrocarbon accumulation on the after
treatment system. The process and system disclosed herein can be
used not only on vehicles but all engine systems including marine,
locomotive, electronic power, machines, etc.
[0016] FIG. 1 is an illustration of an engine system in an
exemplary vehicle 100 that utilizes the after treatment process
according to the disclosure. The vehicle 100 can be a wheeled dump
truck or any off-highway vehicle being used in any manner or
operation. The vehicle 100 is shown to include a chassis 112. The
chassis 112 may be supported by wheels 113 (or tracks on other
locomotion devices), and itself support an operator cabin 114 and
an engine 115. A dump body 118 may be positioned above an actuator
system 119, with both being supported by the chassis 112, as well.
The actuator system 119 may include one or more hydraulic cylinders
(not shown) to raise and lower the dump body 118 at a proximal end
120, and thereby inclining the dump body 118 in order to expel a
payload 121 at a distal end 122.
[0017] In one aspect of the disclosure such as in a cold
environment, the vehicle 100 will be left in idle for an extended
period of time, such as overnight as it is difficult to start the
diesel engine in cold temperatures. During extended low temperature
operation, hydrocarbon can accumulate on the catalyst. Thus, when
the operator operates the engine system within the vehicle 100 from
the idle state to a working state, the after treatment system would
heat up and can cause an exothermic reaction due to the accumulated
hydrocarbons and thereby, potentially damaging the catalyst and
other parts of the after treatment system. It should be noted that
the processes and systems described herein can be applied in all
types of temperature, weather and load conditions.
[0018] FIG. 2 is a perspective view of an after treatment system
220 with the top removed to illustrate the components, and exhaust
flow. The after treatment system 220 can include a housing 222 that
is supported on a base support 224 adapted to mount the after
treatment system to a power system, such as a diesel engine 115 of
the vehicle 100. The housing 222 can include a forward first wall
226, an opposing rearward second wall 228, and respective third and
fourth sidewalls 230, 232. However, it should be appreciated that
terms like forward, rearward and side are used only for
illustrative purposes and should not be construed as a limitation
on the claims. Additionally, extending between the forward first
wall 226 and rearward second wall 228 and located midway between
the third and fourth sidewalls 230, 232 can be an imaginary central
system axis line 234.
[0019] To receive the untreated exhaust gasses into the after
treatment system 220, one or more inlets 240 can be disposed
through the forward first wall 226 of the housing 222 and can be
coupled in fluid communication to the exhaust channel from an
exhaust system. In the aspect illustrated, the after treatment
system 220 includes two inlets 240 arranged generally in parallel
and centrally located between the third and fourth sidewalls 230,
232 on either side of the system axis line 234 so that the entering
exhaust gasses are directed toward the rearward second wall 228.
However, other aspects of the after treatment system 220 may
include different numbers and/or locations for the inlets 240. To
enable the exhaust gasses to exit the after treatment system 220,
two outlets 242 can also be disposed through the forward first wall
226 of the housing 222. Each outlet 242 can be parallel to the
centrally oriented inlets 240.
[0020] To treat or condition the exhaust gasses, the housing 222
can contain various types or kinds of after treatment devices
through which the gasses of the exhaust flow are directed. For
example, and following the arrows indicating exhaust flow through
the after treatment system 220, in order to slow the velocity of
the incoming exhaust gasses for treatment, the inlets 240 can each
be communicatively associated with an expanding, cone-shaped
diffuser 244 mounted exteriorly of the forward first wall 226. Each
cone-shaped diffuser 244 can direct the exhaust gasses to an
associated diesel oxidation catalyst (DOC) 246 located proximate
the forward first wall 226 inside the housing 222 that then directs
the exhaust gasses to a common collector duct 248 centrally aligned
along the system axis line 234. The DOC 246 can contain materials
such as platinum group metals like platinum or palladium, which can
catalyze carbon monoxide and hydrocarbons in the exhaust gasses to
water and carbon dioxide via the following possible reactions:
CO+1/2O.sub.2=CO.sub.2 (1)
[HC]+O.sub.2=CO.sub.2+H.sub.2O (2)
[0021] To further reduce emissions in the exhaust gasses and
particularly to reduce nitrogen oxides such as NO and NO.sub.2,
sometimes referred to as NO.sub.x, the after treatment system 220
may include an SCR system 250. In the SCR process, a liquid or
gaseous reducing agent is introduced to the exhaust system and
directed through an SCR catalyst along with the exhaust gasses. The
SCR catalyst can include materials that cause the exhaust gasses to
react with the reducing agent to convert the NO.sub.x to nitrogen
(N.sub.2) and water (H.sub.2O). A common reducing agent is urea
((NH.sub.2).sub.2CO), though other suitable substances such as
ammonia (NH.sub.3), Diesel Exhaust Fluid (DEF) can be used in the
SCR process. The reaction may occur according to the following
general formula:
NH.sub.3+NO.sub.x=N.sub.2+H.sub.2O (3)
[0022] Referring again to FIG. 2, to introduce the reducing agent,
the SCR system 250 includes a reductant injector 252 located
downstream of the collector duct 248 and upstream of a centrally
aligned mixing duct 254 that channels the exhaust gasses toward the
rearward second wall 228 of the housing 222. The reductant injector
252 can be in fluid communication with a storage tank or reservoir
storing the reducing agent and can periodically, or continuously,
inject a quantity of the reducing agent into the exhaust gas flow
in a process sometimes referred to as dosing. The amount of
reducing agent introduced can be dependent upon the NO.sub.x load
of the exhaust gasses. The mixing duct 254 uniformly intermixes the
reductant agent with the exhaust gasses before they enter the
downstream SCR catalysts. Disposed at the end of the mixing duct
254 proximate the rearward second wall 228 can be a diffuser 256
that redirects the exhaust gas/reductant agent mixture toward the
third and fourth sidewalls 230, 232 of the after treatment system
220. The third and fourth sidewalls 230, 232 can redirect the
exhaust gas/reductant agent mixture generally back towards the
forward first wall 226.
[0023] To perform the SCR reaction process, the after treatment
system 220 can include a first SCR module 260 disposed proximate
the third sidewall 230 and a second SCR module 262 disposed toward
the fourth sidewall 232. The first and second SCR modules 260, 262
are oriented to receive the redirected exhaust gas/reducing agent
mixture. The first and second SCR modules 260, 262 can accommodate
one or more SCR catalysts 264, sometimes referred to as after
treatment bricks. The term after treatment brick, however, may
refer to a variety of exhaust after treatment devices, which SCR
catalysts are a subset of Moreover, in different aspects, the SCR
modules 260, 262 may be configured to accommodate any different
number of after treatment bricks that may be in different shapes,
sizes and/or configurations and that may operate by the same or
different reaction processes.
[0024] To accommodate the plurality of SCR catalysts 264, the first
and second SCR modules 260, 262 can include one or more sleeves 270
that can slidably receive the catalysts. The sleeves 270 can be
generally elongated, tubular structures having a first end 274 and
an opposing second end 276 aligned along a longitudinal sleeve axis
272. In some aspects, the first end 274 may be designated as an
upstream end and the second end 276 may be designated as the
downstream end thereby establishing the gas flow direction through
the sleeves 270. In other aspects, the flow direction through the
first and second SCR modules 260, 262 may be at least partially
reversible so that either the first end or second end 274, 276 may
function alternatively as the upstream or downstream ends. In those
aspects that include more than one sleeve 270 in the first and
second SCR modules 260, 262, the sleeves can be supported in a
truss or frame 266 made, for example, from formed sheet metal or
cast materials. The frame 266 can be oriented so that the first
ends 274 are directed toward the respective third and fourth
sidewalls 230, 232 and the second ends 276 communicate with a
central region 280 of the after treatment system 220 generally
surrounding but fluidly separated from the mixing duct 254. The
central region 280 can direct the treated exhaust gases forward to
the outlets 242 disposed through the forward first wall 226. In
various aspects, one or more additional exhaust treatment devices
can be disposed in the after treatment system 220 such as diesel
particulate filters 282 for removing soot.
[0025] FIG. 3 is a flow diagram 300 of a method of protecting
against hydrocarbon damage to an after treatment system according
to the disclosure. An engine out hydrocarbon estimator 304 is used
to estimate or calculate the amount of unburnt hydrocarbon that is
present in the exhaust stream of the engine 115. One or more engine
system parameters 302 can be provided to the engine out hydrocarbon
estimator 304 so that it can estimate the unutilized hydrocarbon.
The engine system parameters 302 may include the amount of fuel
being injected into the engine, the engine speed (average speed or
current speed), the engine timing, the total exhaust flow mass, the
crank mode, inject enable, inlet manifold pressure or temperature,
coolant temperature, ambient temperature and pressure, and other
parameters that are stored in the various electronic control
modules or sensors of the engine or vehicle.
[0026] These engine system parameters 302 will affect the amount of
unburnt hydrocarbon that is present in the exhaust stream and
enters the after treatment system 220. The exhaust stream can
include engine slobber, blow by and the like. Once one or more
engine system parameters, such as engine speed and the amount of
fuel being injected are provided to the engine out hydrocarbon
estimator 304, the estimator can include various known Maps or look
up tables for a particular vehicle and or engine type (size) to
estimate the unutilized hydrocarbon in grams/hour. These Maps and
look up tables may be stored in the engine system computer 400 as
discussed in FIG. 4.
[0027] Alternatively, models may be designed to provide such
estimations and are well within the disclosure. One model equation
can be:
C HC adsorbed t = r adsorption - r desorption - r oxidation
##EQU00001## [0028] C.sub.HC.sub.absorbed=Concentration of adsorbed
hydrocarbon [mol volume.sup.-1] [0029] r.sub.1=rate of reaction i
[mol volume.sup.-1 time.sup.-1] This model equation can be used to
estimate the amount of hydrocarbon adsorbed (onto the SCR), which
equal the rate of reaction for adsorption minus the rate of
reaction for desorption minus the rate of reaction for
oxidation.
[0030] The respective vehicle electronic control modules provide
engine system parameters 302. As the engine out hydrocarbon
estimator 304 includes various look up tables and Maps depending on
the vehicle and/or engine type, the engine out hydrocarbon
estimator 304 can provide an estimate or a calculation of engine
hydrocarbon not utilized, such as engine hydrocarbon startup 308.
At engine start up, the engine may produce a great amount of
unburnt hydrocarbon because the engine has not warmed up to peak
operating temperatures, where it is more efficient. Engine
hydrocarbon start up 308 can also include warm and failed starts.
The engine out hydrocarbon estimator 304 can also provide estimates
of unburnt hydrocarbon in the exhaust stream for various engine
hydrocarbon run mode 310, such as idle, fast, slow, coasting
downhill, etc.
[0031] At this point, depending on the operating condition of the
vehicle 100, either the estimate for the unburnt hydrocarbon in the
exhaust stream at engine startup 308 or unburnt hydrocarbon in the
exhaust stream for various engine hydrocarbon run mode 310 is
provided to a catalyst hydrocarbon mass integrator 312, which
determines the amount of hydrocarbon added or removed for each time
step and subsequently calculates an overall hydrocarbon mass
accumulated onto the catalyst 264. Additional after treatment
system information 306 that can also be provided to the catalyst
hydrocarbon mass integrator 312 includes the SCR temperature or any
other catalyst being used in the after treatment system 220, the
total mass exhaust flow, the catalyst volume, and the current
hydrocarbon loading already accumulated on the after treatment
system 220. Based on this information, the catalyst hydrocarbon
mass integrator 312 calculates or estimates the catalyst
hydrocarbon mass 314, which is the amount of hydrocarbon that has
accumulate on the catalyst 264 at any given time.
[0032] If the accumulated hydrocarbon on the after treatment system
220 is not properly addressed, then an exothermic event may occur
and damage the catalyst 264 and/or the catalyst active sites that
may be covered by the accumulated hydrocarbon are not available to
the reductant, thereby, increasing slip of exhaust gases and
reductant derivatives, such as ammonia, into the environment.
Various methods and systems are disclosed herein that can be
implemented to mitigate the effects caused by accumulated
hydrocarbon on the catalyst 264 including maximizing catalyst
conversion capability 316 and catalyst inlet temperature protection
318.
[0033] Maximizing catalyst conversion capability 316 involves
fluctuating the amount of reductant added to the after treatment
system 220 by the reductant injector 252. As more hydrocarbon
accumulates on the catalyst 264, the active sites available on the
catalyst are decreased and thus, the reductant used to convert the
NO.sub.x to nitrogen (N.sub.2) and water (H.sub.2O) are not being
utilized and are eventually exhausted into the environment and may
exceed the allowable amount of ammonia slip in the case of ammonia
producing reducing agents. Engine system computer 400 (discussed in
FIG. 4 below) can control the reductant injector 252 so that the
amount of reductant is fluctuated depending on the amount of
calculated or estimated catalyst hydrocarbon mass 314 accumulation
on the after treatment system 220. The more hydrocarbon
accumulation on the catalyst 264 and thus, more blocked active
sites on the catalyst 264 may require the engine system computer
400 to decrease the amount of reductant introduced into the exhaust
stream in order to have more efficient conversion of the NOx.
Alternatively, if the amount of calculated or estimated catalyst
hydrocarbon mass 314 accumulation on the after treatment system 220
is less or more active sites on the catalyst 264 are available,
then the engine system computer 400 can increase the amount of
reductant introduced into the exhaust stream for more efficient
conversion of the NOx.
[0034] In addition or alternatively to optimizing catalyst
performance, the catalyst inlet temperature protection 318 can also
be used. In this aspect, in order to prevent or reduce the
possibility of an exothermic event occurring within the catalyst
264, the engine 115 exhaust flow and engine exhaust temperatures
are controlled by controlling multiple aspects of the engine
operation including, but not limited to, the engine speed, fueling,
and backpressure of the engine system within the vehicle 100. In
cold environments, the diesel engine 115 is often left in idle for
an extended period of time, including overnight, as diesel engines
are difficult to start up in cold temperatures. By only allowing
the engine to slowly warm up to operating temperatures, the
exothermic event may be avoided. The engine system computer 400
(discussed in FIG. 4) can be utilized to control various electronic
control modules including modules that control engine speed and
fuel injection. In one aspect, the electronic control modules can
throttle or limit the amount of fuel that is injected into the
engine in order to control the engine load and thus, can allow the
exhaust temperatures to slowly increase regardless of the throttle
position of the fuel pedal being operated by the operator. An
estimated or measured temperature sensor located on or near the
catalyst or in or near the after treatment system 220 can provided
feedback to the engine system computer 400. In another aspect, the
engine system computer 400 can control the electronic control
modules to perform an automated engine warm up program based upon
the calculated or estimated catalyst hydrocarbon mass 314. The
engine warm up program can take into account the type of engine,
the current engine temperature, the ambient temperature, the
catalyst hydrocarbon mass 314 and the like in order to prevent a
rapid increase in temperature of the engine 115 during
operation.
[0035] FIG. 4 illustrates components of an engine system computer
400 according to the disclosure. The engine system computer 400 can
include a microprocessor 402, a main memory 404, a network
interface 406, a storage device 408, a display 414, a wireless
interface 416, a user interface 418 and bus line 420. The
microprocessor 402 may be a single microprocessor or multiple
microprocessors, multiple core microprocessors, a field
programmable gate array (FPGA), application-specific integrated
circuit (ASIC), controllers and the like. It is contemplated that
microprocessor 402 may communicate with other machine sensors (not
shown), such as gas sensors, NO.sub.x sensors, NH.sub.3 sensors,
throttle position sensors, mass flow, rate sensors, pressure
sensors, temperature sensors, intake manifold sensors, throttle
position sensors, and/or any other system sensors that may provide
information related to the operational characteristics of the
engine.
[0036] Main memory 404 may contain certain software needed for the
microprocessor 402, such as the bios and the like. In addition to
or alternatively, there is a storage device 408 that includes an
operating system 410 for the engine system computer 400 and
programs 412, such as software programs (discussed herein) to
protect the after treatment system 220 from the effects of
hydrocarbon accumulation. The storage device 408 may be a hard
drive, optical drive, a flash memory and the like. The operating
system 410 can be any system such as Windows.RTM., Mac O/S.RTM.,
Linux, Android.RTM. and the like. Storage device 408 can also store
one or more multi-dimensional Maps. Multi-dimensional Maps may be
generated from steady-state simulations and/or empirical data and
may include equations, graphs and/or tables related to the
operational characteristics of after treatment system 220 and other
information including hydrocarbon accumulation. For example, Maps
may include equations, graphs and/or tables that relate a SCR
device temperature (either measured or predicted) to an ability of
SCR device to store reducing agent and to convert emissions gases.
The equations may relate to calculating or estimating the engine
out hydrocarbon estimator 304 and/or the catalyst hydrocarbon mass
314. The inputs fed into Maps may include engine air mass flow
rate, manifold correction factor, inlet gas ratio, inlet NO.sub.2
over NO.sub.x ratio, inlet pressure, and inlet temperature of SCR
device, ambient temperature, a total fuel quantity and/or engine
speed. It is contemplated that Maps may further include other
formulations and weighting and may include further inputs, such as,
a space velocity and the like.
[0037] A display 414 can be provided and be placed at any
convenient place in the vehicle 100 including a heads up display
(HUD), a built-in display on the console of the vehicle, a remote
and movable display and the like. The display 414 can be LED, VGA,
OLED, plasma, touch screen and the like. Network interface 406 can
connect the engine system computer 400 to other devices, such as a
diagnostic tool, the after treatment system 220, reductant injector
252, sensors, electronic control modules, and the like. The network
interface 406 can be USB, Fire wire, Thunderbolt, Ethernet, and the
like. The wireless interface 416 can communicate with external
devices, sensors, electronic control modules, networks, computers,
diagnostic tools, tablets, and the like via various communication
protocols, such as Wi-Fi, LAN, WAN, Bluetooth, wireless Ethernet,
infrared, cellular, satellite and the like. A user interface 418
allows a user or an operator to interact with the engine system
computer 400. The user interface 418 may be the touchscreen display
414. The components of the engine system computer may communicate
with each other on the bus line 420.
[0038] FIG. 5 is a diagram 500 of steps to protect the after
treatment system from the effects of hydrocarbon accumulation
according to the disclosure. The protection starts at step 502. At
step 504, engine system parameters 302 received from various
electronic control modules of the vehicle 100 may be received at
the microprocessor 402, which may be running the after treatment
protection software. Engine system parameters 302 may include the
amount of fuel being injected into the engine, the engine speed
(average speed or current speed), the engine timing or idle
rotation per minute, the total mass exhaust flow, the crank mode,
inject enable, inlet manifold pressure or temperature, coolant
temperature, ambient temperature and pressure, and other
parameters. At step 506, microprocessor 402 estimates or calculates
the engine out hydrocarbon in parts per million (PPM) using the
engine out hydrocarbon estimator 304, which may also be a software
module and includes various Maps, equations, or look up tables.
Additionally, at step 508, a correction factor, such as a manifold
correction factor, which may include intake manifold temperature
may also be inputted into the engine out hydrocarbon estimator 304.
At step 510, the microprocessor 402 converts to mass rate in
grams/hour and then alternatively to grams/per second. Total mass
exhaust flow from an electronic control module can also be used to
convert to mass rate. The engine out hydrocarbon estimator 304 can
provide mass rate for engine hydrocarbon at startup 308 and various
engine hydrocarbon run mode 310. At step 512, the microprocessor
402 can use the catalyst hydrocarbon mass integrator 312, which can
be a software module, to calculate the catalyst hydrocarbon mass
314 using the mass rate for engine hydrocarbon at startup 308
and/or various engine hydrocarbon run mode 310. Also inputted into
the catalyst hydrocarbon mass integrator 312 are one or more of the
following SCR in temperature, total mass exhaust flow, catalyst
volume and current HC loading. Once the catalyst hydrocarbon mass
is calculated various methods disclosed herein may be utilized to
protect the after treatment system.
[0039] The methods may include one or both of steps 514 and 516. At
step 514, the microprocessor 402 using the network interface 406
that is in communication with the reductant injector 252 controls
the amount of reductant being injected into the after treatment
system 220. If there is too much hydrocarbon accumulating on the
after treatment system, such as the SCR, then the catalyst sites
are covered and then excess reductant not being utilized will flow
out of the exhaust stream into the environment causing excess
ammonia slip beyond the acceptable range. Depending on the
operating conditions of the engine 115, size of engine and other
factors, the amount of reductant being injected can vary from about
0 to about 40 kg/hr. and normal operating conditions can be about
1-30 kg/hr. The amount of reductant being injected will be
modulated by the microprocessor 402 depending on the amount of
estimated or calculated hydrocarbon mass 314 on the after treatment
system 220. Thus, the more hydrocarbon mass 314 on the after
treatment system 220 that is beyond a predetermined level, the
amount of reductant being injected will be modulated accordingly.
Conversely, if the amount of hydrocarbon mass 314 is less than the
predetermined level, then the amount of reductant being injected
will be adjusted. The microprocessor 402 can continuously monitor
and estimate or calculate the catalyst hydrocarbon mass 314 and
adjust the reductant being injected accordingly.
[0040] At step 516, the microprocessor 402 through the network
interface 406 communicates with the electronic control modules to
modulate the engine operation due to the accumulation of the
hydrocarbon on the after treatment system 220. At idle, the engine
temperature may be around 50-150.degree. C. depending on the
ambient temperature. If the engine is allowed to increase to higher
operating temperatures such as 300.degree. C. or higher in a short
amount of time, an exothermic event may occur due to the
accumulated hydrocarbon on the after treatment system 220. Thus,
the microprocessor 402 will control the engine temperature to
gradually ramp up regardless of fuel throttle's position. In one
aspect, the microprocessor 402 may modulate the amount of fuel that
is being injected into the engine 115 regardless of the throttle
position.
[0041] The steps outlined in FIG. 5 do not have to be performed in
any particular order and any or all of the engine parameters need
not be used to calculate the catalyst hydrocarbon mass. The steps
may be performed automatically via software, processor, and
electronic control modules without operator intervention or
direction. Additionally, the processes and systems described herein
are constantly and automatically estimating, calculating,
adjusting, modulating, etc., due to different operating parameters
of the engine system.
[0042] The present disclosure can be realized as
computer-executable instructions on computer-readable media. The
computer-readable media includes all possible kinds of media in
which computer-readable data is stored or included or can include
any type of data that can be read by a computer or a processing
unit. The computer-readable media include for example and not
limited to storing media, such as magnetic storing media (e.g.,
ROMs, floppy disks, hard disk, and the like), optical reading media
(e.g., CD-ROMs (compact disc-read-only memory), DVDs (digital
versatile discs), re-writable versions of the optical discs, and
the like), hybrid magnetic optical disks, organic disks, system
memory (read-only memory, random access memory), non-volatile
memory such as flash memory or any other volatile or non-volatile
memory, other semiconductor media, electronic media,
electromagnetic media, infrared, and other communication media such
as carrier waves (e.g., transmission via the Internet or another
computer). Communication media generally embodies computer-readable
instructions, data structures, program modules or other data in a
modulated signal such as the carrier waves or other transportable
mechanism including any information delivery media.
Computer-readable media such as communication media may include
wireless media such as radio frequency, infrared microwaves, and
wired media such as a wired network. Also, the computer-readable
media can store and execute computer-readable codes that are
distributed in computers connected via a network. The computer
readable medium also includes cooperating or interconnected
computer readable media that are in the processing system or are
distributed among multiple processing systems that may be local or
remote to the processing system. The present disclosure can include
the computer-readable medium having stored thereon a data structure
including a plurality of fields containing data representing the
techniques of the present disclosure.
INDUSTRIAL APPLICABILITY
[0043] The disclosure may be applicable to any after treatment
systems including the catalyst therein that need protection from
the effects of hydrocarbon accumulation. Accumulation of
hydrocarbon on the catalyst can cause an exothermic event or
blocking of the catalyst's active site leading to deteriorated
catalyst performance. Specifically, the disclosure may include a
controller with software modules that calculates or estimates the
amount of hydrocarbon that accumulates on a catalyst of the after
treatment system. Based on the amount of accumulation the
controller can prevent the exothermic event by controlling the
ramp-up temperature of the engine and/or fluctuate the amount of
reductant being injected to decrease the amount of reductant
slip.
[0044] The engine system computer 400 can include a microprocessor
402, a main memory 404, a network interface 406, a storage device
408, a display 414, a wireless interface 416, a user interface 418
and bus line 420. The microprocessor 402 may communicate with
sensors, such as gas sensors, NOx sensors, NH3 sensors, throttle
position sensors, mass flow rate sensors, pressure sensors,
temperature sensors, intake manifold sensors, throttle position
sensors, and/or any other system sensors that may provide
information related to the operational characteristics of the
engine. Storage device 408 can also store one or more
multi-dimensional Maps, models or governing equations.
Multi-dimensional Maps, models or equations may be generated from
steady-state simulations and/or empirical data and may include
equations, graphs and/or tables related to the operational
characteristics of after treatment system and other information
including hydrocarbon accumulation. The microprocessor 402 can
estimate or calculate the engine out hydrocarbon in parts per
million (PPM) using the engine out hydrocarbon estimator 304, which
may also be a software module and includes various Maps, equations
and/or look up tables. Engine parameters received from various
electronic control modules of the vehicle 100 may be received at
the microprocessor 402. The engine out hydrocarbon estimator 304
can provide mass rate for engine hydrocarbon at startup 308 and/or
various engine hydrocarbon run mode 310. The microprocessor 402 can
use the catalyst hydrocarbon mass integrator 312, which can be a
software module, to calculate the catalyst hydrocarbon mass 314
using the mass rate for engine hydrocarbon at startup 308 and/or
various engine hydrocarbon run mode 310. Also inputted into the
catalyst hydrocarbon mass integrator 312 are one or more of the
following SCR in temperature, total mass exhaust flow, catalyst
volume and current HC loading. Once the catalyst hydrocarbon mass
is calculated various methods disclosed herein may be utilized to
protect the after treatment system.
[0045] Network interface 406 can connect the engine system computer
400 to other devices, such as a diagnostic tool, the after
treatment system 220, reductant injector 252, sensors, electronic
control modules, and the like. The microprocessor 402 using the
network interface 406 that is in communication with the reductant
injector 252 to control the amount of reductant being injected into
the after treatment system. The amount of reductant being injected
will be modulated by the microprocessor 402 depending on the amount
of estimated or calculated hydrocarbon mass 314 on the after
treatment system. The microprocessor 402 can control how the engine
temperature ramps up regardless of how much throttle that the
operator is giving the engine. In one aspect, the microprocessor
402 may control the amount of fuel that is being injected into the
engine regardless of the throttle position.
[0046] Although specific exemplary aspects of the disclosure have
been described, internal and external components and configurations
may be implemented in reverse to provide the same benefits provided
by the inventive aspects described. In addition, it will be
appreciated by one skilled in the art that other related items can
be incorporated and used along with aspects derived from the
disclosure.
[0047] The many features and advantages of the disclosure are
apparent from the detailed specification, and thus, it is intended
by the appended claims to case all such features and advantages of
the disclosure which fall within the true spirit and scope of the
disclosure. Further, since numerous modifications and variations
will readily occur to those skilled in the art, it is not desired
to limit the disclosure to the exact construction and operation
illustrated and described, and accordingly, all suitable
modifications and equivalents may be resorted to, falling within
the scope of the disclosure.
* * * * *