Title of Invention

A METHOD AND A SYSTEM FOR EMISSIONS CONTROL FOR INTERNAL COMBUSTION ENGINES

Abstract A system may include a hydrocarbon (HC) absorber positioned in an exhaust flow path and an electrically heated catalyst (EHC) positioned in the exhaust flow path downstream of the HC absorber.
Full Text General Motors No. GP-309177-PTH-CD
Attorney Docket No. 8540P-000481
HYBRID HC ABSORBER / EHC PZEV EXHAUST ARCHITECTURE
FIELD
[0001] The present disclosure relates to improved emissions control,
and more particularly to emissions control for internal combustion engines.
BACKGROUND
[0002] The statements in this section merely provide background
information related to the present disclosure and may not constitute prior art.
[0003] A hybrid vehicle includes an internal combustion engine and an
electric motor to provide vehicle propulsion. Vehicles including an internal
combustion engine may also include a catalytic converter to reduce carbon
monoxide, volatile organic compounds (VOCs) and NOx.
[0004] Catalytic converters may generally operate efficiently at fairly
high temperatures. When the engine is first started, the catalytic converter is
typically not effective in removing emissions in the exhaust until the catalytic
converter reaches an operating temperature called the light-off temperature.
Before light-off temperature is reached, HC emissions may not be effectively
processed by the catalytic converter.
SUMMARY
[0005] According to the present disclosure, a system may include a
hydrocarbon (HC) absorber positioned in an exhaust flow path and an electrically
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Attorney Docket No. 8540P-000481
heated catalyst (EHC) positioned in the exhaust flow path downstream of the HC
absorber.
[0006] A method of reducing vehicle emissions includes operating a
combustion engine during a first time period and a second time period after the
first time period, trapping hydrocarbons (HC) from an exhaust gas from the
combustion engine during the first time period in a HC absorber that is in
communication with the exhaust gas and upstream of an electrically heated
catalyst (EHC) that is in communication with the exhaust gas, energizing the
electrically heated catalyst (EHC) during the first time period, and oxidizing HC
from the exhaust gas within the EHC during the second time period.
[0007] Further areas of applicability will become apparent from the
description provided herein. It should be understood that the description and
specific examples are intended for purposes of illustration only and are not
intended to limit the scope of the present disclosure.
DRAWINGS
[0008] The drawings described herein are for illustration purposes only
and are not intended to limit the scope of the present disclosure in any way.
[0009] FIG. 1 is a schematic illustration of a hybrid vehicle according to
the present disclosure;
[0010] FIG. 2 is a schematic illustration of an alternate exhaust
configuration for the hybrid vehicle of FIG. 1; and
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[0011] FIG. 3 is a flow diagram illustrating operation of the hybrid
vehicle of FIG. 1.
DETAILED DESCRIPTION
[0012] The following description is merely exemplary in nature and is
not intended to limit the present disclosure, application, or uses. For purposes of
clarity, the same reference numbers will be used in the drawings to identify
similar elements. As used herein, the term "module" refers to an application
specific integrated circuit (ASIC), an electronic circuit, a processor (shared,
dedicated, or group) and memory that execute one or more software or firmware
programs, a combinational logic circuit, or other suitable components that provide
the described functionality.
[0013] Referring now to FIG. 1, a hybrid vehicle 10 includes an internal
combustion engine 12 with a plurality of cylinders 14 and an electric motor 16.
The engine 12 is connected to an output shaft 18 that provides rotational power
to a transmission 20. A generator 22 is driven by the engine 12 and provides
charging current to a rechargeable battery 24. The motor 16 converts power
from the battery 24 to mechanical power. The mechanical power is applied to an
input shaft of the transmission 20. The transmission 20 combines power from
the engine 12 and motor 16 to provide power to a drive axle 23. The engine 12
and motor 16 may provide propulsion simultaneously or independently.
[0014] The hybrid vehicle 10 may be a plug-in hybrid. "Plug-in" refers
to hybrid vehicles that include a relatively large rechargeable battery 24 providing
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Attorney Docket No. 8540P-000481
an extended time between battery 24 recharges. The result is a corresponding
savings in fuel and a reduction in emissions by allowing the engine 12 to be shut
off for longer periods of time. The plug-in hybrid battery 24 may also be
externally recharged between trips, providing a recharge of the battery 24 without
running the engine 12.
[0015] The engine 12 is connected to an exhaust system 25 including
an exhaust manifold 26, a plurality of catalytic converters 30-1, 30-2, 30-3,
collectively 30, a hydrocarbon (HC) absorber 31, an electrically heated catalyst
(EHC) 32, and a muffler 50. The exhaust manifold 26 directs exhaust gas 28
from the engine 12 to catalytic converters 30, HC absorber 31, and an EHC 32.
The plurality of catalytic converters 30 may be three-way catalytic converters.
Catalytic converters 30-1, 30-2 may be close-mounted to the engine 12 to
promote their efficient heating to light-off.
[0016] HC absorber 31 may be disposed between catalytic converters
30-1, 30-2 and catalytic converter 30-3. EHC 32 may be disposed between HC
absorber 31 and catalytic converter 30-3. EHC 32 provides supplemental
heating to reduce time to catalytic converter 30-3 light-off. As can be
appreciated, the EHC 32 may be a separate assembly or formed integrally as
part of the catalytic converter 30-3. As seen in FIG. 2, an alternate exhaust
system 125 may be generally similar to exhaust system 25. However, rather
than including a separate catalytic converter 30-3 and HC absorber 31, a
combined HC absorber and catalytic converter 131 may be used. Combined HC
absorber and catalytic converter 131 may be located between an EHC 132 and
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catalytic converters 130-1, 130-2. Combined HC absorber and catalytic
converter 131 may generally provide a reduced package size relative to catalytic
converter 30-3 and HC absorber 31 of exhaust system 25.
[0017] The EHC 32 may be powered by the rechargeable battery 24.
Using rechargeable battery 24 as a power source for EHC 32 may generally
provide for a reduced heating time for EHC 32 relative to traditional, non-hybrid
powertrain systems due to the relatively high power provided by rechargeable
battery 24. For example, EHC 32 may be heated to a temperature of at least 400
degrees Celsius in approximately 15 seconds or less. The catalytic converter 30-
3, HC absorber 31, and EHC 32 may be an integrated "add-on" to an existing
exhaust system architecture.
[0018] An engine control module 40 communicates with the EHC 32,
the engine 12, the motor 16, the battery 24 and receives inputs from a number of
sensors. The sensors may include an engine coolant temperature sensor 42, a
first plurality of oxygen sensors 46-1, 46-2, collectively 46, a second plurality of
oxygen sensors 48-1, 48-2, collectively 48, and an EHC temperature sensor 54.
Oxygen sensors 46 may be located between the engine 12 and the catalytic
converters 30-1, 30-2. The oxygen sensors 46 sense oxygen content in the
exhaust gas to properly adjust the air-fuel ratio for proper stoichiometry. As can
be appreciated, the oxygen sensors 46 may be located in other positions or
omitted. Oxygen sensors 48 provide diagnostic information relating to catalytic
converters 30-1, 30-2 and may be located downstream from the plurality of
catalytic converters 30-1, 30-2.
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Attorney Docket No. 8540P-000481
[0019] The temperature of EHC 32 may be directly measured via a
temperature sensor 54 or the engine control module 40 may estimate the EHC
temperature. Various data, including current passing through EHC 32, the
voltage supplied to EHC 32, the volume flow rate of exhaust gas 28 passing
through EHC 32 and the time elapsed for each of these parameters may be
provided to engine control module 40 to estimate the temperature.
[0020] With reference to FIG. 3, operation of hybrid vehicle 10 during a
cold start condition is generally illustrated at flow diagram 200 and may generally
include operating engine 12 during first and second time periods. A
determination of an engine cold start condition may be made in a number of
ways including monitoring an engine coolant temperature provided by engine
coolant temperature sensor 42. For simplicity, operation with respect to exhaust
system 25 will be discussed with the understanding that the discussion applies
equally to exhaust system 125. The first time period may generally correspond
to an initial period after engine 12 has been started and the second time period
may include the period immediately thereafter. EHC 32 may be energized at a
time generally corresponding to the starting of engine 12 at step 202.
Alternatively, EHC 32 may be energized slightly before or after engine 12 has
been started.
[0021] As indicated above, operation of engine 12 results in an exhaust
gas 28 being supplied to exhaust system 25. Exhaust gas travels from catalytic
converters 30-1, 30-2 to HC absorber 31, to EHC 32, and finally to catalytic
converter 30-3. During operation of engine 12 during the first time period, engine
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12 may be operated at a first set of operating conditions, as indicated at step
204, and catalytic converters 30 may be at a temperature below a light-off
temperature needed to oxidize hydrocarbons present in the exhaust gas 28.
However, HC absorber 31 is able to trap HC in the exhaust gas 28 during
operation in the first time period, as indicated at step 206. The HC may remain
trapped by HC absorber 31 during operation at temperatures below
approximately 100 degrees Celsius. The temperature of HC absorber 31 may
generally be at or below 100 degrees Celsius during the first time period.
[0022] To minimize emissions during the first time period, operation of
engine 12 at the first set of operating conditions may include operation at an air-
fuel ratio that is less than a stoichiometric ratio (rich operation). Rich operation of
engine 12 generally provides a reduced NOx emission level, but increases HC
emissions. As previously described, HC absorber 31 traps HC emissions of
engine 12 during the first time period. Accordingly, this architecture optimizes
both HC and NOx emissions.
[0023] As indicated above and illustrated at step 202, during the first
time period, EHC 32 is energized and is increasing in temperature. Once EHC
32 reaches a temperature needed for oxidation of HC, the second time period for
engine operation may begin and engine 12 may be operated at a second set of
operating conditions, as indicated at step 208. Oxidation of HC may occur at
temperatures greater than 400 degrees Celsius. During the second time period,
HC absorber 31 may exceed a trapping temperature and release the HC
previously stored therein, as indicated at step 210. For example, HC absorber
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31 may release trapped HC when it reaches temperatures greater than 100
degrees Celsius. Since EHC 32 is heated independently of exhaust gas 28 and
is disposed downstream of HC absorber 31, EHC 32 may oxidize HC released
from HC absorber 31, as indicated at step 212, prior to catalytic converter 30-3
reaching the light-off temperature.
[0024] The second set of operating conditions may include an air-fuel
ratio of engine 12 generally at a stoichiometric ratio. The second time period
may generally correspond to HC absorber 31 exceeding the trapping
temperature and EHC 32 exceeding the oxidation or light-off temperature. EHC
32 may continue to be energized during the second time period until engine 12 is
out of a cold start condition. More specifically, the second time period may
terminate once exhaust system 25 is capable of processing exhaust gas 28
without the use of HC absorber 31 or EHC 32, such as when catalytic converters
30 reach light-off temperature.
[0025] In an alternate operation or in addition to the operation of engine
12 during a cold start condition, as discussed above, engine 12 may be operated
initially using motor 16 as indicated at step 214. More specifically, before
injecting fuel into cylinders 14 and firing engine 12, motor 16 may rotate the
crankshaft for a predetermined period. The crankshaft of engine 12 may be
initially rotated to a speed of greater than or equal to 350 RPM by motor 16.
Engine 12 may be operated using motor 16 until a predetermined operating
condition is reached. Additional steps may also be taken to reduce a warm-up
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Attorney Docket No. 8540P-000481
time for operation of exhaust system 25. For example, operation of engine 12 at
the first set of operating conditions may include retarding the spark of engine 12.
[0026] Furthermore, the foregoing discussion discloses and describes
merely exemplary embodiments of the present disclosure. One skilled in the art
will readily recognize from such discussion, and from the accompanying
drawings and claims, that various changes, modifications and variations may be
made therein without departing from the spirit and scope of the disclosure as
defined in the following claims.
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General Motors No. GP-309177-PTH-CD
Attorney Docket No. 8540P-000481
CLAIMS
What is claimed is:
1. A method, comprising:
operating a combustion engine during a first time period and a
second time period after the first time period;
trapping hydrocarbons (HC) from an exhaust gas from the
combustion engine during the first time period in a HC absorber that is in
communication with the exhaust gas and upstream of an electrically heated
catalyst (EHC) that is in communication with the exhaust gas;
energizing the EHC during the first time period; and
oxidizing HC from the exhaust gas within the EHC during the
second time period.
2. The method of claim 1 further comprising operating the combustion
engine at an air-fuel ratio that is less than a stoichiometric air-fuel ratio during the
first time period.
3. The method of claim 1 further comprising operating the combustion
engine at a generally stoichiometric air-fuel ratio during the second time period.
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General Motors No. GP-309177-PTH-CD
Attorney Docket No. 8540P-000481
4. The method of claim 1 wherein said operating includes operating
the combustion engine in a hybrid vehicle including the combustion engine and
an electric motor powered by a battery.
5. The method of claim 4 wherein said energizing includes energizing
the EHC with the battery.
6. The method of claim 4 further comprising rotating a crankshaft of
the combustion engine using the electric motor when the combustion engine is
not in an operating state.
7. The method of claim 1 further comprising determining if the engine
is operating at a cold start condition.
8. The method of claim 7 wherein operation of the combustion engine
during the first time period corresponds to a cold start condition.
9. The method of claim 1 wherein said trapping includes operating the
HC absorber at a temperature less than 100 degrees Celsius.
10. The method of claim 1 wherein said oxidizing includes operating
the EHC at a temperature greater than 400 degrees Celsius.
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General Motors No. GP-309177-PTH-CD
Attorney Docket No. 8540P-000481
11. The method of claim 10 wherein the EHC reaches a temperature of
400 degrees Celsius before the HC absorber reaches a temperature of 100
degrees Celsius.
12. The method of claim 1 further comprising releasing the trapped HC
from the HC absorber to the exhaust gas during the second time period.
13. The method of claim 12 wherein said releasing occurs during or
after said oxidizing.
14. The method of claim 1 wherein said energizing occurs
simultaneously with or before said operating.
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General Motors No. GP-309177-PTH-CD
Attorney Docket No. 8540P-000481
15. A system, comprising:
a hydrocarbon (HC) absorber positioned in an exhaust flow path;
and
an electrically heated catalyst (EHC) positioned in said exhaust flow
path downstream of the HC absorber.
16. The system of claim 15 further comprising a control module in
communication with a battery to selectively supply power to said EHC based on
operating conditions of a combustion engine.
17. The system of claim 16 further comprising an electric power system
including an electric motor to provide powered propulsion.
18. The system of claim 17 wherein said electric motor is in
communication with said combustion engine to provide initial rotation of a
crankshaft of said combustion engine when said combustion engine is in a non-
operating state.
19. The system of claim 15 further including a catalytic converter
disposed downstream of said HC absorber.

A system may include a hydrocarbon (HC) absorber positioned in an
exhaust flow path and an electrically heated catalyst (EHC) positioned in the
exhaust flow path downstream of the HC absorber.

Documents:

00467-kol-2008-abstract.pdf

00467-kol-2008-claims.pdf

00467-kol-2008-correspondence others.pdf

00467-kol-2008-description complete.pdf

00467-kol-2008-drawings.pdf

00467-kol-2008-form 1.pdf

00467-kol-2008-form 2.pdf

00467-kol-2008-form 3.pdf

00467-kol-2008-form 5.pdf

467-KOL-2008-(02-05-2014)-ABSTRACT.pdf

467-KOL-2008-(02-05-2014)-CLAIMS.pdf

467-KOL-2008-(02-05-2014)-CORRESPONDENCE.pdf

467-KOL-2008-(02-05-2014)-DESCRIPTION (COMPLETE).pdf

467-KOL-2008-(02-05-2014)-DRAWINGS.pdf

467-KOL-2008-(02-05-2014)-FORM-1.pdf

467-KOL-2008-(02-05-2014)-FORM-2.pdf

467-KOL-2008-(02-05-2014)-OTHERS.pdf

467-KOL-2008-(21-10-2013)-ANNEXURE TO FORM 3.pdf

467-KOL-2008-(21-10-2013)-CORRESPONDENCE.pdf

467-KOL-2008-(21-10-2013)-DESCRIPTION (COMPLETE).pdf

467-KOL-2008-(21-10-2013)-FORM-1.pdf

467-KOL-2008-(21-10-2013)-FORM-2.pdf

467-KOL-2008-(21-10-2013)-OTHERS.pdf

467-KOL-2008-(21-10-2013)-PA.pdf

467-KOL-2008-(21-10-2013)-PETITION UNDER RULE 137.pdf

467-KOL-2008-ASSIGNMENT.pdf

467-KOL-2008-CORRESPONDENCE OTHERS 1.1.pdf

467-KOL-2008-CORRESPONDENCE OTHERS-1.1.pdf

467-kol-2008-form 18.pdf

467-KOL-2008-PRIORITY DOCUMENT.pdf


Patent Number 262919
Indian Patent Application Number 467/KOL/2008
PG Journal Number 39/2014
Publication Date 26-Sep-2014
Grant Date 24-Sep-2014
Date of Filing 06-Mar-2008
Name of Patentee GM GLOBAL TECHNOLOGY OPERATIONS, INC.
Applicant Address 300 GM RENAISSANCE CENTER DETROIT, MICHIGAN
Inventors:
# Inventor's Name Inventor's Address
1 EUGENE V. GONZE 9103 ANACAPA BAY PINCKNEY, MICHIGAN 48169
2 FRANK AMENT 1681 ROLLING WOODS DRIVE TROY, MICHIGAN 48098
3 HALIM G SANTOSO 30969 STONE RIDGE DRIVE APT. 3307 WIXOM, MICHIGAN 48393
PCT International Classification Number F01N9/00; F01N3/08; F01N11/00
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 11/803,683 2007-05-15 U.S.A.