US20200191077A1 - Control system for variable displacement engine - Google Patents
Control system for variable displacement engine Download PDFInfo
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- US20200191077A1 US20200191077A1 US16/218,093 US201816218093A US2020191077A1 US 20200191077 A1 US20200191077 A1 US 20200191077A1 US 201816218093 A US201816218093 A US 201816218093A US 2020191077 A1 US2020191077 A1 US 2020191077A1
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Images
Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D41/00—Electrical control of supply of combustible mixture or its constituents
- F02D41/008—Controlling each cylinder individually
- F02D41/0087—Selective cylinder activation, i.e. partial cylinder operation
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
- F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
- F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
- F01N3/18—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control
- F01N3/20—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control specially adapted for catalytic conversion ; Methods of operation or control of catalytic converters
- F01N3/2006—Periodically heating or cooling catalytic reactors, e.g. at cold starting or overheating
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N9/00—Electrical control of exhaust gas treating apparatus
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D13/00—Controlling the engine output power by varying inlet or exhaust valve operating characteristics, e.g. timing
- F02D13/02—Controlling the engine output power by varying inlet or exhaust valve operating characteristics, e.g. timing during engine operation
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D13/00—Controlling the engine output power by varying inlet or exhaust valve operating characteristics, e.g. timing
- F02D13/02—Controlling the engine output power by varying inlet or exhaust valve operating characteristics, e.g. timing during engine operation
- F02D13/06—Cutting-out cylinders
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D17/00—Controlling engines by cutting out individual cylinders; Rendering engines inoperative or idling
- F02D17/02—Cutting-out
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D41/00—Electrical control of supply of combustible mixture or its constituents
- F02D41/0025—Controlling engines characterised by use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures
- F02D41/0047—Controlling exhaust gas recirculation [EGR]
- F02D41/005—Controlling exhaust gas recirculation [EGR] according to engine operating conditions
- F02D41/0055—Special engine operating conditions, e.g. for regeneration of exhaust gas treatment apparatus
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D41/00—Electrical control of supply of combustible mixture or its constituents
- F02D41/02—Circuit arrangements for generating control signals
- F02D41/021—Introducing corrections for particular conditions exterior to the engine
- F02D41/0235—Introducing corrections for particular conditions exterior to the engine in relation with the state of the exhaust gas treating apparatus
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D41/00—Electrical control of supply of combustible mixture or its constituents
- F02D41/02—Circuit arrangements for generating control signals
- F02D41/021—Introducing corrections for particular conditions exterior to the engine
- F02D41/0235—Introducing corrections for particular conditions exterior to the engine in relation with the state of the exhaust gas treating apparatus
- F02D41/024—Introducing corrections for particular conditions exterior to the engine in relation with the state of the exhaust gas treating apparatus to increase temperature of the exhaust gas treating apparatus
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D41/00—Electrical control of supply of combustible mixture or its constituents
- F02D41/02—Circuit arrangements for generating control signals
- F02D41/021—Introducing corrections for particular conditions exterior to the engine
- F02D41/0235—Introducing corrections for particular conditions exterior to the engine in relation with the state of the exhaust gas treating apparatus
- F02D41/024—Introducing corrections for particular conditions exterior to the engine in relation with the state of the exhaust gas treating apparatus to increase temperature of the exhaust gas treating apparatus
- F02D41/0255—Introducing corrections for particular conditions exterior to the engine in relation with the state of the exhaust gas treating apparatus to increase temperature of the exhaust gas treating apparatus to accelerate the warming-up of the exhaust gas treating apparatus at engine start
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N2340/00—Dimensional characteristics of the exhaust system, e.g. length, diameter or volume of the apparatus; Spatial arrangements of exhaust apparatuses
- F01N2340/02—Dimensional characteristics of the exhaust system, e.g. length, diameter or volume of the apparatus; Spatial arrangements of exhaust apparatuses characterised by the distance of the apparatus to the engine, or the distance between two exhaust treating apparatuses
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
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- F01N2430/00—Influencing exhaust purification, e.g. starting of catalytic reaction, filter regeneration, or the like, by controlling engine operating characteristics
- F01N2430/02—Influencing exhaust purification, e.g. starting of catalytic reaction, filter regeneration, or the like, by controlling engine operating characteristics by cutting out a part of engine cylinders
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N2900/00—Details of electrical control or of the monitoring of the exhaust gas treating apparatus
- F01N2900/06—Parameters used for exhaust control or diagnosing
- F01N2900/08—Parameters used for exhaust control or diagnosing said parameters being related to the engine
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N2900/00—Details of electrical control or of the monitoring of the exhaust gas treating apparatus
- F01N2900/06—Parameters used for exhaust control or diagnosing
- F01N2900/16—Parameters used for exhaust control or diagnosing said parameters being related to the exhaust apparatus, e.g. particulate filter or catalyst
- F01N2900/1602—Temperature of exhaust gas apparatus
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N2900/00—Details of electrical control or of the monitoring of the exhaust gas treating apparatus
- F01N2900/06—Parameters used for exhaust control or diagnosing
- F01N2900/16—Parameters used for exhaust control or diagnosing said parameters being related to the exhaust apparatus, e.g. particulate filter or catalyst
- F01N2900/1626—Catalyst activation temperature
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
- F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
- F01N3/0807—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by using absorbents or adsorbents
- F01N3/0814—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by using absorbents or adsorbents combined with catalytic converters, e.g. NOx absorption/storage reduction catalysts
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D2200/00—Input parameters for engine control
- F02D2200/02—Input parameters for engine control the parameters being related to the engine
- F02D2200/08—Exhaust gas treatment apparatus parameters
- F02D2200/0802—Temperature of the exhaust gas treatment apparatus
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
- Y02A50/20—Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/10—Internal combustion engine [ICE] based vehicles
- Y02T10/12—Improving ICE efficiencies
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/10—Internal combustion engine [ICE] based vehicles
- Y02T10/40—Engine management systems
Definitions
- the present disclosure relates to control systems for variable displacement or skip-fire internal combustion engines.
- One or more cylinders in a variable displacement internal combustion engine may be shut down or deactivated while the engine is operating, which results in the engine being powered by less than all the cylinders.
- a vehicle includes an internal combustion engine, a conduit, and a controller.
- the internal combustion engine has a plurality of cylinders.
- the conduit is configured to channel exhaust gas away from the cylinders and to a catalyst.
- the controller is programmed to, in response to starting the engine and a temperature of the catalyst being less than a threshold, operate a first of the plurality of cylinders alone followed by operating the first and a second of the plurality of cylinders alone to increase the temperature of the catalyst toward the threshold.
- a method of heating a catalyst in a vehicle includes, in response to starting an engine and a temperature of the catalyst being less than a threshold, operating a first of a plurality of cylinders in the engine alone to produce exhaust gas to increase the temperature of the catalyst toward the threshold, and operating the first and a second of the plurality of cylinders in the engine alone, after operating the first cylinder alone, to produce exhaust gas to increase the temperature of the catalyst toward the threshold, wherein the second cylinder is adjacent to the first cylinder.
- a vehicle includes an internal combustion engine, an exhaust pipe, and a controller.
- the internal combustion engine has first and second banks of cylinders.
- the exhaust pipe is configured to channel exhaust gas away from the first bank of cylinders and to a catalytic converter.
- the controller is programmed to, in response to starting the engine and a temperature of the catalyst being less than a threshold, operate a first cylinder from the first bank of cylinders alone followed by operating the first cylinder and a second cylinder from first bank of cylinders alone to increase the temperature of the catalytic converter toward the threshold.
- FIG. 1 is a schematic illustration of a vehicle including a single cylinder of an internal combustion engine that has multiple cylinders, an air intake system, a fuel delivery system, and an exhaust system;
- FIG. 2 is a schematic illustration of the multiple cylinders of the internal combustion engine and the exhaust system
- FIGS. 3A-3C illustrate a mechanism that is configured to disable the valves in a variable displacement engine
- FIGS. 4A-4B illustrate a flowchart of a control method for controlling a variable displacement engine
- FIG. 5 is a graph comparing the difference between the total emissions produced when a single cylinder of an engine is utilized to heat the catalyst to the light-off temperature and the total emissions produced when all of the cylinders of the engine are utilized to heat the catalyst to the light-off temperature is illustrated;
- FIG. 6 illustrates an exhaust gas distribution over a front face of a catalyst.
- FIGS. 1 and 2 a vehicle 10 and an internal combustion engine 12 that includes multiple cylinders are illustrated.
- the schematic of FIG. 1 illustrates a single cylinder 14 of the internal combustion engine 12 , an air intake system 16 , a fuel delivery system 18 , and an exhaust system 20 .
- the schematic of FIG. 2 illustrates the multiple cylinders 14 of the engine 12 and the exhaust system of the engine 12 .
- the single cylinder 14 illustrated in FIG. 1 may be representative of one or all of the cylinders 14 of the engine 12 .
- the air intake system 16 and fuel delivery system 18 illustrated in FIG. 1 are representative of the systems that deliver air and fuel, respectively, to all of the cylinders 14 of the engine 12
- the exhaust system 20 illustrated in FIG. 1 is representative of the system that channels exhaust gas away from all of the cylinders 14 of the engine 12 .
- the engine 12 includes an engine block 22 that defines each of the cylinders 14 .
- a piston 24 is disposed within each of the cylinders 14 .
- the pistons 24 are configured to transfer the energy that results from combusting fuel within each cylinder 14 into kinetic energy, which is utilized to rotate a crankshaft 26 .
- Each piston 24 is connected to the crankshaft 26 via a connecting rod 28 .
- the crankshaft 26 then transfers the rotational energy to one or more drive wheels (not shown) of the vehicle 10 in order to propel the vehicle 10 .
- Intermediate components such as driveshafts, a torque converter, a transmission gearbox, universal joints, differentials, etc. may be disposed between the crankshaft 26 and the drive wheels.
- the intermediate components are configured to transfer the rotational power of the crankshaft 26 to the drive wheels.
- the air intake system 16 includes one or more manifolds, pipes, ducts, or conduits 30 that are configured to channel air from the ambient surroundings and into the cylinders 14 .
- the amount of air that is being channeled into the cylinders 14 may be controlled by the throttle valve 32 .
- An air filter 34 may be disposed proximate to the intake of the air intake system 16 .
- Each of the cylinders 14 includes an air intake valve 36 is that is configured to establish fluid communication between the cylinder 14 and the air intake system 16 when in an opened position and isolate the cylinder 14 from the air intake system 16 when in a closed position.
- the air intake valve 36 of each cylinder 14 will be in an opened position during the intake stroke of the respective piston 24 and closed during the compression, combustion, and exhaust strokes of the respective piston 24 .
- the exhaust system 20 includes one or more manifolds, pipes, ducts, or conduits 38 there configured to channel exhaust gas away from the cylinders 14 and to the ambient surroundings.
- the exhaust system 20 includes a first catalyst 40 (or first catalytic converter) that is configured to reduce the amount of emissions (e.g., NO x gases or unspent hydrocarbons) in the exhaust gas that is channeled to the ambient air or surroundings.
- the exhaust system 20 may include a second catalyst 42 (or second catalytic converter) that is configured to further reduce the amount of emissions in the exhaust gas that are channeled to the ambient air or surroundings.
- the second catalyst 42 may be a redundant catalyst that only further reduces the emissions in the exhaust when the first catalyst 40 is not operating at full capacity or has some malfunction.
- the exhaust system 20 may further include a particulate filter 44 that is configured to reduce particulate matter in the exhaust and a muffler 46 that is configured to reduce noise.
- the particulate filter 44 and the muffler 46 may each be downstream of the first catalyst 40 and the second catalyst 42 .
- Each of the cylinders 14 includes an exhaust valve 48 is that is configured to establish fluid communication between the cylinder 14 and the exhaust system 20 when in an opened position and isolate the cylinder 14 from the exhaust system 20 when in a closed position.
- the exhaust valve 48 of each cylinder 14 will be in an opened position during the exhaust stroke of the respective piston 24 and closed during the intake, compression, and combustion strokes of the respective piston 24 .
- One or more camshafts may be configured to open and close the air intake valve 36 and exhaust valve 48 of each cylinder 14 .
- the camshafts may be connected to the crankshaft 26 by a gearing arrangement, belted arrangement, or some other arrangement to ensure that the air intake valves 36 and exhaust valves 48 are opening and closing when necessary. More specifically, the connection between the crankshaft 26 and the one or more camshafts will ensure that the air intake valve 36 of each cylinder 14 is in the opened position during the intake stroke of the respective piston 24 and closed during the compression, combustion, and exhaust strokes of the respective piston 24 . The connection between the crankshaft 26 and the one or more camshafts will also ensure that the exhaust valve 48 of each cylinder 14 is in the opened position during the exhaust stroke of the respective piston 24 and closed during the intake, compression, and combustion strokes of the respective piston 24 .
- the first catalyst 40 and second catalyst 42 each may consist of a brick that is coated in alumina.
- the alumina in turn is coated with rhodium, cerium, and platinum or palladium.
- the rhodium is configured to reduce the amount NO x gases (combinations of nitrogen and oxygen such NO, NO 2 , etc.) that are present within the exhaust. More specifically, the rhodium is configured to convert the NO x gases into nitrogen (N 2 ) and oxygen (O 2 ) by reacting the NO x gases with oxygen.
- the platinum or palladium is configured to reduce the amount of unspent hydrocarbons (e.g., C 8 H 18 or C 1 H 4 ) that are present within the exhaust.
- the platinum or palladium is configured to convert the hydrocarbons into carbon dioxide (CO 2 ) and water (H 2 O) by reacting the hydrocarbons with oxygen.
- the rhodium may also reduce the amount of unspent hydrocarbons within the exhaust, however, the rhodium is primarily utilized to reduce the amount of amount NO x gases that are present within the exhaust.
- the platinum or palladium may also reduce the amount of amount NO x gases that are present within the exhaust, however, the platinum or palladium is primarily utilized to reduce the amount of unspent hydrocarbons that are present within the exhaust.
- the cerium acts to store oxygen, which is then supplied to the rhodium and the platinum or palladium to effect the reactions described above to convert NO x gases into nitrogen (N 2 ) and oxygen (O 2 ) and to convert the unspent hydrocarbons into carbon dioxide (CO 2 ) and water (H 2 O).
- the particulate filter 44 is configured to filter any particulate matter out of the exhaust gas in order to prevent the particulate matter from being channeled to the ambient air or surroundings.
- Particulate matter may refer to any particle within the exhaust guest including rust, oil mixed with any solid material (e.g., metal shavings), simply oil by itself, carbon particles, suspended particulate matter (SPM), thoracic and respirable particles, inhalable coarse particles, which are coarse particles with a diameter between 2.5 and 10 micrometers ( ⁇ m), fine particles with a diameter of 2.5 ⁇ m or less, ultrafine particles, soot (i.e., a mass of impure carbon particles resulting from the incomplete combustion of hydrocarbons), etc.
- the fuel delivery system 18 is configured to deliver fuel to each of the cylinders 14 . More specifically, the fuel delivery system may include a fuel tank for storing fuel, conduits that establish fluid communication between the fuel tank and fuel injectors 50 , and a fuel pump that is configured to direct the fuel from the fuel tank, through the conduits, and to each of the fuel injectors 50 . Each cylinder 14 also includes a spark plug 52 that is configured to ignite the air and fuel mixture that is within the cylinder 14 and push down on the respective piston 24 during the power stroke of the cylinder 14 .
- the vehicle 10 includes a controller 54 , which may be a powertrain control unit (PCU). While illustrated as one controller, the controller 54 may be part of a larger control system and may be controlled by various other controllers throughout the vehicle 10 , such as a vehicle system controller (VSC). It should therefore be understood that the controller 54 and one or more other controllers can collectively be referred to as a “controller” that controls various components of the vehicle 10 in response to signals from various sensors to control functions such as, shutting down one or more of the cylinders 14 of the engine 12 during a skip-fire mode, selecting or scheduling shifts of a vehicle transmission, adjusting the air-fuel mixture being delivered to the engine 12 , etc.
- PCU powertrain control unit
- VSC vehicle system controller
- the controller 54 may include a microprocessor or central processing unit (CPU) that is in communication with various types of computer readable storage devices or media.
- Computer readable storage devices or media may include volatile and nonvolatile storage in read-only memory (ROM), random-access memory (RAM), and keep-alive memory (KAM), for example.
- KAM is a persistent or non-volatile memory that may be used to store various operating variables while the CPU is powered down.
- Computer-readable storage devices or media may be implemented using any of a number of known memory devices such as PROMs (programmable read-only memory), EPROMs (electrically PROM), EEPROMs (electrically erasable PROM), flash memory, or any other electric, magnetic, optical, or combination memory devices capable of storing data, some of which represent executable instructions, used by the controller 54 in controlling the engine 12 or subcomponents of the vehicle 10 .
- PROMs programmable read-only memory
- EPROMs electrically PROM
- EEPROMs electrically erasable PROM
- flash memory or any other electric, magnetic, optical, or combination memory devices capable of storing data, some of which represent executable instructions, used by the controller 54 in controlling the engine 12 or subcomponents of the vehicle 10 .
- the controller 54 may be configured to increase or decrease the power output of the engine 12 . More specifically, the controller 54 may be configured to increase or decrease the power output of the engine 12 by increasing or decreasing the airflow and fuel flow into each cylinder 14 .
- the airflow may be increased by adjusting the throttle valve 32 towards a fully open position or decreased by adjusting the throttle valve towards a fully closed position.
- the fuel flow may be increased by opening the fuel injectors 50 for longer periods of time during each injection of fuel into the cylinder 14 or decreased by opening the fuel injectors 50 for shorter periods of time during each injection of fuel into the cylinder 14 .
- the controller 54 may also increase or decrease the power output of the engine 12 by either retarding or advancing the spark timing of the spark plugs 52 .
- a mass airflow sensor 56 may be configured to measure the amount of air flowing into the air intake system 16 , which is eventually delivered to the cylinders 14 , and communicate the amount of air flowing into the air intake system 16 to the controller 54 .
- a throttle position sensor 58 may be configured to communicate the position of the throttle valve 32 to the controller 54 .
- the controller 54 may also be in communication with each of the spark plugs 52 , the fuel system 18 , and each of the fuel injectors 50 .
- the controller may adjust the throttle valve 32 position to increase or decrease airflow into the cylinders 14 , adjust the timing of the spark plugs 52 , and/or adjust the amount of fuel being delivered into the cylinders 14 to either increase or decrease the power output of the engine 12 to meet the power demand.
- the power demand may be input into the controller 54 by an operator of the vehicle 10 when the operator engages an accelerator pedal 60 . Under certain circumstances the power demand may be based on a presetting that is stored as control logic within the controller 54 . For example, if the vehicle operator is not depressing the accelerator pedal 60 and the engine 12 is on, the amount of power the engine 12 is producing may be adjusted to a preset idle value.
- the engine 12 may be configured to operate at a stoichiometric air-fuel mass ratio, a lean air-fuel mass ratio, or a rich air-fuel mass ratio.
- the air-fuel mass ratio may simply be referred to as the air-fuel ratio.
- Stoichiometric air-fuel mass ratio has a value of 14.7 to 1.
- a rich air-fuel mass ratio will be less than 14.7 to 1 and a lean air-fuel mass ration will be greater than 14.7 to 1.
- An air-fuel equivalence ratio has an air-fuel mass ratio that is stoichiometric when ⁇ is equal to 1, an air-fuel mass ratio that is rich when ⁇ is less than 1, and an air-fuel mass ratio that is lean when ⁇ is greater than 1.
- the air-fuel mass ratio may be controlled, via the controller 54 , by adjusting the amount of air and fuel flowing into the cylinders 14 .
- a first lambda or oxygen sensor 62 may be disposed within the conduits 38 of the exhaust system 20 between the cylinders 14 and the first catalyst 40 .
- the first oxygen sensor 62 may be a universal heated exhaust gas oxygen sensor.
- the first oxygen sensor 62 is configured to measure the amount of oxygen (O 2 ) that is within the exhaust gas exiting the cylinder 14 . Based on the measured amount oxygen in the exhaust gas, the first oxygen sensor 62 generates a signal (e.g., a voltage or current) that correlates with the current air-fuel equivalence ratio ( ⁇ ) that the engine 12 is operating at.
- the signal generated by the first oxygen sensor 62 may indicative of a lean, stoichiometric, or rich current air-fuel equivalence ratio ( ⁇ ).
- the first oxygen sensor 62 communicates the air-fuel ratio or air-fuel equivalence ratio ( ⁇ ) measurement to the controller 54 , which provides a feedback control to the controller 54 .
- the feedback control may include adjusting the air and/or fuel flowing (i.e., flow rates) into the cylinders 14 via the controller 54 if the air-fuel equivalence ratio ( ⁇ ) measured by the first oxygen sensor 62 is different than the air-fuel equivalence ratio ( ⁇ ) that is being commanded to the engine 12 .
- the feedback control may include adjusting the air and/or fuel flowing into the cylinders 14 to drive the air-fuel equivalence ratio ( ⁇ ) that is being measured by the first oxygen sensor 62 toward the air-fuel equivalence ratio ( ⁇ ) that is being commanded to the engine 12 .
- a second lambda or oxygen sensor 64 which has the same functionality as the first oxygen sensor 62 , may be disposed within the conduits 38 of the exhaust system 20 between the first catalyst 40 and the second catalyst 42 .
- the second oxygen sensor 64 is utilized to determine the efficiency at which the first catalyst 40 reduces the amount of emissions within the exhaust gas.
- the second oxygen sensor 64 is configured to communicate a signal that correlates with the measured air-fuel equivalence ratio ( ⁇ ) of the exhaust gas back to the controller 54 , after the exhaust gas has passed through the first catalyst 40 .
- a particulate sensor 66 may be disposed within the conduits 38 of the exhaust system 20 between the second catalyst 42 and the particulate filter 44 .
- the particulate sensor 66 is configured to measure the amount of particulate matter within the exhaust gas and communicate the measurement to the controller 54 in the form of a signal (e.g., a voltage or current).
- One or more temperature sensors 63 may be configured to measure the temperature of the first catalyst 40 and/or the second catalyst 42 .
- the temperature sensors 63 are configured to communicate a signal that correlates with a measured temperature of the first catalyst 40 and/or the second catalyst 42 back to the controller 54 .
- the engine 12 also includes an oil pan or sump 68 .
- An oil pump 70 is configured to direct oil out of the sump 68 and towards various lubrication points 72 , such as any of the bearings, journals, valve stems, or any of the other moving parts within the engine 12 .
- a pressure sensor 74 may be configured to measure the pressure of the oil that is being output from the oil pump 70 . The pressure sensor 74 may then communicate the oil pressure to the controller 54 .
- An oil level sensor 76 may be configured to measure the level of the oil within the pan or sump 68 . The oil level sensor 76 may then communicate the level of the oil to the controller 54 .
- the engine 12 is illustrated as an eight-cylinder engine that includes a first bank 78 of four cylinders 14 and a second bank 80 of four cylinders 14 .
- the first bank 78 of cylinders includes an exhaust system 20 that is configured to channel the exhaust gas away from the first bank 78 of cylinders only.
- the second bank 80 of cylinders includes an exhaust system 20 that is configured to channel the exhaust gas away from the second bank 80 of cylinders only.
- FIG. 2 illustrates an eight-cylinder engine that includes two banks of cylinders where each bank has its own exhaust system 20 , it should be understood that the engine 12 may include two or more cylinders that comprise of one or more banks of cylinders where each bank of cylinders may include a separate exhaust system.
- the engine 12 may be a variable displacement engine or a skip-fire engine that may be controlled to shut down or deactivate one or more cylinders 14 while the engine 12 is operating, resulting in the engine 12 being powered by less than all the cylinders 14 .
- Shutting down or deactivating a specific cylinder 14 a during skip-fire mode requires shutting down or deactivating the air intake valve 36 , exhaust valve 48 , spark plug 52 , and the fuel injector 50 .
- the engine 12 may be referred to as operating in a skip-fire mode when being powered by less than all of the cylinders 14 .
- the cylinders 14 may be shut down or deactivated in any known pattern to increase the fuel efficiency when conditions are such that the engine 12 may effectively operate in the skip-fire mode to increase fuel efficiency without disturbing the driving requirements of the vehicle operator (e.g., when the number of cylinders can be reduced without reducing the speed of the vehicle). However, it may be desirable to shut down or deactivate the cylinders 14 based on the position of the cylinders 14 in order to directionally equalize the forces that are being transferred to the crankshaft 26 from the pistons 24 .
- which of the cylinders 14 are shut down or deactivated and which of the cylinders 14 are operating may always be changing or rotating when in the skip-fire mode, which may also help to directionally equalize the forces that are being transferred to the crankshaft 26 from the pistons 24 .
- a mechanism 82 that is configured to deactivate the air intake valves 36 and exhaust valves 48 in the variable displacement/skip-fire engine 12 is illustrated.
- the mechanism 82 includes a deactivation arm 84 and a locking pin 86 .
- the locking pin 86 is configured to advance and engage a protrusion 88 that extends outward from the deactivation arm 84 .
- the locking pin 86 is also configured to retract and disengage from the protrusion 88 that extends outward from the deactivation arm 84 .
- a stem valve 90 is secured to an opposing side of the deactivation arm 84 relative to the protrusion 88 .
- the stem valve 90 may be representative of both the air intake valves 36 and the exhaust valves 48 .
- the deactivation arm 84 will rotate about a first pivot 92 when engaged by a camshaft 94 while the locking pin 86 is engaging the protrusion 88 .
- Rotation of the deactivation arm 84 about the first pivot 92 allows the stem valve 90 to transition between a closed position (see FIG. 3A ) and an opened position (see FIG. 3B ).
- the stem valve 90 as depicted in FIGS. 3A and 3B has not been deactivated (i.e., the stem valve 90 will transition between the opened and closed positions in response to rotation of the camshaft 94 ).
- the deactivation arm 84 will rotate about a second pivot 96 , which rotatably secures the deactivation arm 84 to the stem valve 90 , when engaged by the camshaft 94 while the locking pin 86 is disengaged from the protrusion 88 .
- Rotation of the deactivation arm 84 about the second pivot 96 results in the stem valve 90 remaining in the closed position regardless of the position of the camshaft 94 and the position of the deactivation arm 84 (see FIG. 3C ).
- the stem valve 90 as depicted in FIG. 3C has been deactivated (i.e., the stem valve 90 will remain in the closed position and will not transition between the opened and closed positions in response to engagement between the deactivation arm and the camshaft 94 ).
- the locking pin 86 may be advanced and retracted by a pressurized fluid.
- the oil pump 70 may be configured to deliver pressurized oil to a first chamber 98 that is located on a first side of the locking pin 86 in order to advance the locking pin 86 such that the locking pin 86 engages the protrusion 88 .
- the oil pump 70 may also be configured to deliver pressurized oil to a second chamber 100 that is located on a second side of the locking pin 86 in order to retract the locking pin 86 such that the locking pin 86 disengages from the protrusion 88 .
- a first fluid valve 102 may be disposed within a conduit between the oil pump 70 and the first chamber 98 .
- a second valve 104 may be disposed within a conduit between the oil pump in the second chamber 100 .
- the pressurized fluid is delivered to the first chamber 98 when the first valve 102 is open and the second valve 104 is closed.
- the pressurized fluid is delivered to the second chamber 100 and when the first valve 102 is closed and the second valve 104 is open.
- the locking pin 86 is advanced (see FIGS. 3A and 3B ) and the stem valve 90 may transition between the opened and closed positions (i.e., the stem valve 90 has not been deactivated).
- the locking pin 86 is retracted (see FIG. 3C ), the stem valve 90 remains in the closed position, and the stem valve 90 cannot transition to the opened position (i.e., the stem valve 90 has been deactivated).
- the controller 54 may be configured to open and close the first valve 102 and the second valve 104 to either advance or retract the locking to pin 86 to respectivley activate or deactivate the stem valve 90 . More specifically, the controller 54 may be configured to activate or deactivate the air intake valve 36 and the exhaust valve 48 of a particular cylinder 14 by utilizing the mechanism 82 depicted in FIGS. 3A-3C , depending on whether the engine 12 is operating in a mode where the particular cylinder 14 is activated or operating in a skip-fire mode that requires the particular cylinder 14 to be shut down or deactivated. When the air intake valve 36 and the exhaust valve 48 of a particular cylinder 14 are deactivated, the particular cylinder 14 is also deactivated.
- Each valve (air intake valve 36 and exhaust valve 48 ) for each cylinder 14 may include an associated mechanism 82 for disabling the particular valve.
- the mechanism 82 depicted in FIGS. 3A-3C is not intended to be limiting.
- the engine 12 may be a variable displacement/skip-fire engine where the valves of a particular cylinder (and therefore the cylinder itself) may be deactivated by any method known in the art.
- the method 200 may be stored as control logic and/or an algorithm within the controller 54 .
- the controller 54 may be programmed to implement the method 200 by controlling the various components of the vehicle 10 .
- the method 200 begins at block 202 where it is determined if the engine 12 has been started. If the engine has not been started, the method 200 recycles back to the beginning of block 202 . If the engine 12 has been started, the method 200 moves on to block 204 where it is determined if a temperature of a catalyst (e.g., the first catalyst 40 and/or the second catalyst 42 ) is less than a first threshold.
- the first threshold may be a light-off temperature of the catalyst.
- the catalyst operates most efficiently (i.e., reduces the maximum amount of emissions within the exhaust gas of the engine 12 ) at temperatures that are at or above the light-off temperature.
- the method 200 moves on to block 206 where the engine 12 is operated according to normal operating conditions. Normal operating conditions may include operating all of the cylinders 14 of the engine 12 or operating the engine 12 in the skip-fire mode if conditions are such that it is desirable to operate in the skip-fire mode.
- the method 200 moves on to block 208 where a first of the cylinders 14 is operated alone (i.e., the first of the cylinders 14 is operated while the remainder of the cylinders 14 are shut down or deactivated) to increase the temperature of the catalyst toward the first threshold.
- the method 200 moves on to block 210 where it is determined if the temperature of the catalyst has increased to a value that is greater than or equal to the first threshold while the first of the cylinders 14 is operated alone. If the temperature of the catalyst has increased to a value that is greater than or equal to the first threshold while the first of the cylinders 14 is operated alone, the method 200 moves on to block 206 where the engine 12 is operated according to the normal operating conditions, which may entail initiating operation of all of the remainder of the cylinders 14 or a portion of the remainder of the cylinders 14 if conditions are such that it is desirable to operate in the skip-fire mode.
- the method 200 moves on to block 212 .
- the temperature of a second of the cylinders 14 of the engine 12 has increased to a value that is greater than a second threshold, while the first of the cylinders 14 is being operated alone.
- the second threshold may correspond to a temperature at which initiating operation of the second of the cylinders 14 will decrease the time required to the heat the catalyst to the first threshold without increasing emissions or without increasing emissions to by value that is greater than a tolerable range.
- the second of the cylinders 14 may become heated via conduction through the engine block 22 while the first of the cylinders 14 is being operated alone.
- the second of the cylinders 14 may be adjacent or next to the first of the of cylinders 14 such that heat transfer via conduction through the engine block 22 is increased or maximized.
- the temperature of the second of the cylinders 14 may be determined by a temperature sensor that is in contact with the second of the cylinders 14 . The temperature sensor may then communicate the temperature of the second of the cylinders 14 to the controller 54 . Alternatively, the temperature of the second of the cylinders 14 may be estimated based on a known or an estimated heat transfer between the first of the cylinders 14 and the second of the cylinders 14 that occurs over a period to time to heat the second cylinder 14 to a temperature that is greater than the second threshold while the first of the cylinders 14 is operating alone. The processes that are occurring in blocks 208 , 210 , and 212 may occur simultaneously.
- the method recycles back to block 208 and eventually to block 210 and/or block 212 . If the temperature of the second of the cylinders 14 has increased to a value that is greater than the second threshold, the method 200 moves on to block 214 , where operation of the second of the cylinders 14 is initiated such that the first and the second of the cylinders 14 of the engine 12 are operated alone (i.e., the first and the second of the cylinders 14 are operated while the remainder of the cylinders 14 are shut down or deactivated) to increase the temperature of the catalyst toward the first threshold.
- the method 200 moves on to block 216 where it is determined if the temperature of the catalyst has increased to a value that is greater than or equal to the first threshold while the first and the second of the cylinders 14 are operated alone. If the temperature of the catalyst has increased to a value that is greater than or equal to the first threshold while the first and the second of the cylinders 14 are operated alone, the method 200 moves on to block 206 where the engine 12 is operated according to the normal operating conditions, which may entail initiating operation of all of the remainder of the cylinders 14 or a portion of the remainder of the cylinders 14 if conditions are such that it is desirable to operate in the skip-fire mode.
- the method 200 moves on to block 218 .
- the temperature of a third of the cylinders 14 of the engine 12 has increased to a value that is greater than a third threshold, while the first and the second of the cylinders 14 are being operated alone.
- the third threshold may correspond to a temperature at which initiating operation of the third of the cylinders 14 will decrease the time required to the heat the catalyst to the first threshold without increasing emissions or without increasing emissions by a value that is greater than a tolerable range.
- the third of the cylinders 14 may become heated via conduction through the engine block 22 while the first and the second of the cylinders 14 are being operated alone.
- the third of the cylinders 14 may be adjacent or next to the first and/or the second of the of cylinders 14 such that heat transfer via conduction through the engine block 22 is increased or maximized.
- the temperature of the third of the cylinders 14 may be determined by a temperature sensor that is in contact with the third of the cylinders 14 . The temperature sensor may then communicate the temperature of the third of the cylinders 14 to the controller 54 .
- the temperature of the third of the cylinders 14 may be estimated based on a known or an estimated heat transfer between the first and/or the second of the cylinders 14 and the third of the cylinders 14 that occurs over a period to time to heat the third cylinder 14 to a temperature that is greater than the third threshold while the first and the second of the cylinders 14 are operating alone.
- the processes that are occurring in blocks 214 , 216 , and 218 may occur simultaneously.
- the method 200 recycles back to block 214 and eventually to block 216 and/or block 218 .
- the method 200 moves on to block 220 , where operation of the third of the cylinders 14 is initiated such that the first, the second, and the third of the cylinders 14 of the engine 12 are operated alone (i.e., the first, the second, and the third of the cylinders 14 are operated while the remainder of the cylinders 14 are shut down or deactivated) to increase the temperature of the catalyst toward the first threshold.
- the method 200 moves on to block 222 where it is determined if the temperature of the catalyst has increased to a value that is greater than or equal to the first threshold while the first, the second, and the third of the cylinders 14 are operated alone. If the temperature of the catalyst has increased to a value that is greater than or equal to the first threshold while the first, the second, and the third of the cylinders 14 are operated alone, the method 200 moves on to block 206 where the engine 12 is operated according to the normal operating conditions, which may entail initiating operation of all of the remainder of the cylinders 14 or a portion of the remainder of the cylinders 14 if conditions are such that it is desirable to operate in the skip-fire mode.
- the method 200 may recycle back to block 220 .
- the method 200 may begin operation addition cylinders 14 , similar to the initiating of operation of the second and third of the cylinders 14 (e.g., adjacent cylinders may be brought into operation once they have reach a temperature at which initiating operation of the cylinders 14 will decrease the time required to the heat the catalyst to the first threshold without increasing emissions or without increasing emissions by a value that is greater than a tolerable range).
- the order at which operation of the cylinders 14 is initiated, after starting the engine 12 to heat the catalyst, may be based on several alternative factors. For example, alternatively to initiating the operation of the cylinders 14 in an order that is based on the temperature of the cylinders 14 , as described according to method 200 , the operation of the cylinders 14 may be initiated in an order that ranges from which of cylinders 14 is closest to catalyst 40 along a path of the exhaust conduit 38 to which of the cylinders 14 is furthest from the catalyst 40 along the path of the exhaust conduit 38 (e.g., the first cylinder 14 is closer to the catalyst than the second and third cylinders 14 , while the second cylinder 14 is closer to the catalyst 40 than the third cylinder 40 ).
- a distance from the first of the plurality of cylinders 14 to the catalyst 40 along the exhaust conduit or pipe 38 may be less than a distance from each of a remainder of the plurality of cylinders 14 to the catalyst 40 along the exhaust conduit or pipe 38
- a distance from the second of the plurality of cylinders 14 to the catalyst 40 along the exhaust conduit or pipe 38 may be less than a distance from each of a remainder of the plurality of cylinders 14 to the catalyst 40 along the exhaust conduit or pipe 38 , other than the first of the cylinders 14 .
- the operation of the cylinders 14 may be initiated in an order that ranges from which of cylinders 14 produces a stream of exhaust gas that has an area of distribution on a front face of the catalyst 40 that is largest to which of cylinders 14 produces a stream of exhaust gas that has an area of distribution on the front face of the catalyst 40 that is the smallest. as opposed to initiating the operation of the cylinders 14 in an order that is based on the temperature of the cylinders 14 , as described according to method 200 .
- the first cylinder 14 may produce a stream of exhaust gas that has an area of distribution on the front face of the catalyst 40 that is larger than the areas of distribution on the front face of the catalyst 40 from the streams of exhaust gas produced by the remainder of the cylinders 14
- the second cylinder 14 may produce a stream of exhaust gas that has an area of distribution on the front face of the catalyst 40 that is larger than the areas of distribution on the front face of the catalyst 40 from the streams of exhaust gas produced by the remainder of the cylinders 14 , other than the first of the cylinders 14 .
- the operation of the cylinders 14 may be initiated in method 200 in an order that ranges from which of cylinders 14 produces the least amount of emissions or particulate matter to which of cylinders 14 produces largest amount of emissions or particulate matter, as opposed to initiating the operation of the cylinders 14 in an order that is based on the temperature of the cylinders 14 , as described according to method 200 .
- This may be determined by operating each cylinder 14 separately and recording the emissions produced by each cylinder via the first lambda or oxygen sensor 62 or recording the amount of particulate matter produced by each cylinder via the particulate sensor 66 .
- the method 200 may be employed separately by individual banks of cylinders 14 (e.g., first bank 78 and second bank 80 of cylinders 14 ) if the engine 12 includes multiple banks of cylinders where each bank has a separate exhaust system that includes a separate catalyst or catalytic converter. It should be understood that the flowchart depicted in FIGS. 4A and 4B is for illustrative purposes only and that the method 200 should not be construed as limited to the flowchart in FIGS. 4A and 4B . Some of the steps of the method 200 may be rearranged while others may be omitted entirely.
- a graph 300 comparing the difference between the total emissions produced when a single cylinder 14 of an engine 12 is utilized to heat the catalyst 40 to the light-off temperature and the total emissions produced when all of the cylinders 14 of the engine 12 are utilized to heat the catalyst 40 to the light-off temperature is illustrated.
- Line 302 represents the temperature of the catalyst 40 over time when all of the cylinders 14 of the engine 12 are utilized to heat the catalyst 40 to the light-off temperature after a cold start of the engine 12 and line 304 represents the rate at which emissions are being expelled from the exhaust system 20 into the ambient air when all of the cylinders 14 of the engine 12 are utilized to heat the catalyst 40 to the light-off temperature after a cold start of the engine 12 .
- Line 306 represents the temperature of the catalyst 40 over time when one of the cylinders 14 of the engine 12 is utilized to heat the catalyst 40 to the light-off temperature after a cold start of the engine 12 and line 308 represents the rate at which emissions are being expelled from the exhaust system 20 into the ambient air when one of the cylinders 14 of the engine 12 is utilized to heat the catalyst 40 to the light-off temperature after a cold start of the engine 12 .
- the catalyst 40 When all the cylinders 14 are utilized to heat the catalyst 40 to the light-off temperature T light_off , the catalyst 40 reaches the light-off temperature T light_off at time t 1 . When one of the cylinders 14 is utilized to heat the catalyst 40 to the light-off temperature T light_off , the catalyst reaches the light-off temperature T light_off at time t 2 , which occurs after time t 1 .
- the total amount of emissions produced when all of the cylinders 14 are utilized to heat the catalyst 40 to the light-off temperature T light_off is represented by the area under line 304 between times t 0 and t 1 .
- the total amount of emissions produced when one of the cylinders 14 is utilized to heat the catalyst 40 to the light-off temperature T light_off is represented by the area under line 308 between times t 0 and t 2 , which is smaller than the area under line 304 between times t 0 and t 1 . Therefore, it can be understood from the graph 300 that decreasing the number of cylinders 14 of the engine 12 to heat the catalyst 40 to the light-off temperature T light_off results in reducing the total number of emissions produced by the engine 12 that are expelled from the exhaust system 20 into the ambient air. However, decreasing the number of cylinders 14 of the engine 12 to heat the catalyst to the light-off temperature T light off also results increasing the time period required to heat the catalyst 40 to the light-off temperature T light_off .
- the number of cylinders 14 that are utilized to heat the catalyst 40 to the light-off temperature T light_off may be adjusted depending on whether or not the goal is to reduce total amount of emissions while heating the catalyst 40 to the light-off temperature T light_off or to reduce the time period required to heat the catalyst 40 to the light-off temperature T light_off .
- FIG. 6 illustrates an exhaust gas distribution over a front face 400 of the catalyst 40 .
- Each stream of exhaust gas from each cylinder 14 has an area of distribution on the front face 400 of the catalyst 40 .
- Area 402 represents the largest area of distribution of exhaust gas, which is produced by a first cylinder
- area 404 represents the second largest area of distribution of exhaust gas, which is produced by a second cylinder
- area 406 represents the third largest and second smallest area of distribution of exhaust gas, which is produced by a third cylinder
- area 408 represents the smallest area of distribution of exhaust gas, which is produced by a fourth cylinder.
- the method 200 may be configured to initiate operation of the cylinders 14 in an order that ranges from which of the cylinders 14 produces a stream of exhaust gas that has an area of distribution on the front face 400 of the catalyst 40 that is largest to which of cylinders 14 produces a stream of exhaust gas that has an area of distribution of exhaust gas on the front face of the catalyst 40 that is the smallest. Therefore, the method 200 may initiate operations of the cylinders 14 in an order that starts with the first cylinder 14 , followed by the second cylinder 14 , followed by the third cylinder 14 , and ending with the fourth cylinder 14 .
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Abstract
A vehicle includes an internal combustion engine, a conduit, and a controller. The internal combustion engine has a plurality of cylinders. The conduit is configured to channel exhaust gas away from the cylinders and to a catalyst. The controller is programmed to, in response to starting the engine and a temperature of the catalyst being less than a threshold, operate a first of the plurality of cylinders alone followed by operating the first and a second of the plurality of cylinders alone to increase the temperature of the catalyst toward the threshold.
Description
- The present disclosure relates to control systems for variable displacement or skip-fire internal combustion engines.
- One or more cylinders in a variable displacement internal combustion engine may be shut down or deactivated while the engine is operating, which results in the engine being powered by less than all the cylinders.
- A vehicle includes an internal combustion engine, a conduit, and a controller. The internal combustion engine has a plurality of cylinders. The conduit is configured to channel exhaust gas away from the cylinders and to a catalyst. The controller is programmed to, in response to starting the engine and a temperature of the catalyst being less than a threshold, operate a first of the plurality of cylinders alone followed by operating the first and a second of the plurality of cylinders alone to increase the temperature of the catalyst toward the threshold.
- A method of heating a catalyst in a vehicle includes, in response to starting an engine and a temperature of the catalyst being less than a threshold, operating a first of a plurality of cylinders in the engine alone to produce exhaust gas to increase the temperature of the catalyst toward the threshold, and operating the first and a second of the plurality of cylinders in the engine alone, after operating the first cylinder alone, to produce exhaust gas to increase the temperature of the catalyst toward the threshold, wherein the second cylinder is adjacent to the first cylinder.
- A vehicle includes an internal combustion engine, an exhaust pipe, and a controller. The internal combustion engine has first and second banks of cylinders. The exhaust pipe is configured to channel exhaust gas away from the first bank of cylinders and to a catalytic converter. The controller is programmed to, in response to starting the engine and a temperature of the catalyst being less than a threshold, operate a first cylinder from the first bank of cylinders alone followed by operating the first cylinder and a second cylinder from first bank of cylinders alone to increase the temperature of the catalytic converter toward the threshold.
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FIG. 1 is a schematic illustration of a vehicle including a single cylinder of an internal combustion engine that has multiple cylinders, an air intake system, a fuel delivery system, and an exhaust system; -
FIG. 2 is a schematic illustration of the multiple cylinders of the internal combustion engine and the exhaust system; -
FIGS. 3A-3C illustrate a mechanism that is configured to disable the valves in a variable displacement engine; -
FIGS. 4A-4B illustrate a flowchart of a control method for controlling a variable displacement engine; -
FIG. 5 is a graph comparing the difference between the total emissions produced when a single cylinder of an engine is utilized to heat the catalyst to the light-off temperature and the total emissions produced when all of the cylinders of the engine are utilized to heat the catalyst to the light-off temperature is illustrated; and -
FIG. 6 illustrates an exhaust gas distribution over a front face of a catalyst. - Embodiments of the present disclosure are described herein. It is to be understood, however, that the disclosed embodiments are merely examples and other embodiments may take various and alternative forms. The figures are not necessarily to scale; some features could be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the embodiments. As those of ordinary skill in the art will understand, various features illustrated and described with reference to any one of the figures may be combined with features illustrated in one or more other figures to produce embodiments that are not explicitly illustrated or described. The combinations of features illustrated provide representative embodiments for typical applications. Various combinations and modifications of the features consistent with the teachings of this disclosure, however, could be desired for particular applications or implementations.
- Referring to
FIGS. 1 and 2 , avehicle 10 and aninternal combustion engine 12 that includes multiple cylinders are illustrated. The schematic ofFIG. 1 illustrates asingle cylinder 14 of theinternal combustion engine 12, anair intake system 16, afuel delivery system 18, and anexhaust system 20. The schematic ofFIG. 2 illustrates themultiple cylinders 14 of theengine 12 and the exhaust system of theengine 12. It should be understood that thesingle cylinder 14 illustrated inFIG. 1 may be representative of one or all of thecylinders 14 of theengine 12. It should further be understood, that theair intake system 16 andfuel delivery system 18 illustrated inFIG. 1 are representative of the systems that deliver air and fuel, respectively, to all of thecylinders 14 of theengine 12, while theexhaust system 20 illustrated inFIG. 1 is representative of the system that channels exhaust gas away from all of thecylinders 14 of theengine 12. - The
engine 12 includes anengine block 22 that defines each of thecylinders 14. Apiston 24 is disposed within each of thecylinders 14. Thepistons 24 are configured to transfer the energy that results from combusting fuel within eachcylinder 14 into kinetic energy, which is utilized to rotate acrankshaft 26. Eachpiston 24 is connected to thecrankshaft 26 via a connectingrod 28. Thecrankshaft 26 then transfers the rotational energy to one or more drive wheels (not shown) of thevehicle 10 in order to propel thevehicle 10. Intermediate components, such as driveshafts, a torque converter, a transmission gearbox, universal joints, differentials, etc. may be disposed between thecrankshaft 26 and the drive wheels. The intermediate components are configured to transfer the rotational power of thecrankshaft 26 to the drive wheels. - The
air intake system 16 includes one or more manifolds, pipes, ducts, orconduits 30 that are configured to channel air from the ambient surroundings and into thecylinders 14. The amount of air that is being channeled into thecylinders 14 may be controlled by thethrottle valve 32. Anair filter 34 may be disposed proximate to the intake of theair intake system 16. Each of thecylinders 14 includes anair intake valve 36 is that is configured to establish fluid communication between thecylinder 14 and theair intake system 16 when in an opened position and isolate thecylinder 14 from theair intake system 16 when in a closed position. Theair intake valve 36 of eachcylinder 14 will be in an opened position during the intake stroke of therespective piston 24 and closed during the compression, combustion, and exhaust strokes of therespective piston 24. - The
exhaust system 20 includes one or more manifolds, pipes, ducts, orconduits 38 there configured to channel exhaust gas away from thecylinders 14 and to the ambient surroundings. Theexhaust system 20 includes a first catalyst 40 (or first catalytic converter) that is configured to reduce the amount of emissions (e.g., NOx gases or unspent hydrocarbons) in the exhaust gas that is channeled to the ambient air or surroundings. Theexhaust system 20 may include a second catalyst 42 (or second catalytic converter) that is configured to further reduce the amount of emissions in the exhaust gas that are channeled to the ambient air or surroundings. Thesecond catalyst 42 may be a redundant catalyst that only further reduces the emissions in the exhaust when thefirst catalyst 40 is not operating at full capacity or has some malfunction. Theexhaust system 20 may further include aparticulate filter 44 that is configured to reduce particulate matter in the exhaust and amuffler 46 that is configured to reduce noise. Theparticulate filter 44 and themuffler 46 may each be downstream of thefirst catalyst 40 and thesecond catalyst 42. Each of thecylinders 14 includes anexhaust valve 48 is that is configured to establish fluid communication between thecylinder 14 and theexhaust system 20 when in an opened position and isolate thecylinder 14 from theexhaust system 20 when in a closed position. Theexhaust valve 48 of eachcylinder 14 will be in an opened position during the exhaust stroke of therespective piston 24 and closed during the intake, compression, and combustion strokes of therespective piston 24. - One or more camshafts (not shown) may be configured to open and close the
air intake valve 36 andexhaust valve 48 of eachcylinder 14. The camshafts may be connected to thecrankshaft 26 by a gearing arrangement, belted arrangement, or some other arrangement to ensure that theair intake valves 36 andexhaust valves 48 are opening and closing when necessary. More specifically, the connection between thecrankshaft 26 and the one or more camshafts will ensure that theair intake valve 36 of eachcylinder 14 is in the opened position during the intake stroke of therespective piston 24 and closed during the compression, combustion, and exhaust strokes of therespective piston 24. The connection between thecrankshaft 26 and the one or more camshafts will also ensure that theexhaust valve 48 of eachcylinder 14 is in the opened position during the exhaust stroke of therespective piston 24 and closed during the intake, compression, and combustion strokes of therespective piston 24. - The
first catalyst 40 andsecond catalyst 42 each may consist of a brick that is coated in alumina. The alumina in turn is coated with rhodium, cerium, and platinum or palladium. The rhodium is configured to reduce the amount NOx gases (combinations of nitrogen and oxygen such NO, NO2, etc.) that are present within the exhaust. More specifically, the rhodium is configured to convert the NOx gases into nitrogen (N2) and oxygen (O2) by reacting the NOx gases with oxygen. The platinum or palladium is configured to reduce the amount of unspent hydrocarbons (e.g., C8H18 or C1H4) that are present within the exhaust. More specifically, the platinum or palladium is configured to convert the hydrocarbons into carbon dioxide (CO2) and water (H2O) by reacting the hydrocarbons with oxygen. The rhodium may also reduce the amount of unspent hydrocarbons within the exhaust, however, the rhodium is primarily utilized to reduce the amount of amount NOx gases that are present within the exhaust. The platinum or palladium may also reduce the amount of amount NOx gases that are present within the exhaust, however, the platinum or palladium is primarily utilized to reduce the amount of unspent hydrocarbons that are present within the exhaust. The cerium acts to store oxygen, which is then supplied to the rhodium and the platinum or palladium to effect the reactions described above to convert NOx gases into nitrogen (N2) and oxygen (O2) and to convert the unspent hydrocarbons into carbon dioxide (CO2) and water (H2O). - The
particulate filter 44 is configured to filter any particulate matter out of the exhaust gas in order to prevent the particulate matter from being channeled to the ambient air or surroundings. Particulate matter may refer to any particle within the exhaust guest including rust, oil mixed with any solid material (e.g., metal shavings), simply oil by itself, carbon particles, suspended particulate matter (SPM), thoracic and respirable particles, inhalable coarse particles, which are coarse particles with a diameter between 2.5 and 10 micrometers (μm), fine particles with a diameter of 2.5 μm or less, ultrafine particles, soot (i.e., a mass of impure carbon particles resulting from the incomplete combustion of hydrocarbons), etc. - The
fuel delivery system 18 is configured to deliver fuel to each of thecylinders 14. More specifically, the fuel delivery system may include a fuel tank for storing fuel, conduits that establish fluid communication between the fuel tank andfuel injectors 50, and a fuel pump that is configured to direct the fuel from the fuel tank, through the conduits, and to each of thefuel injectors 50. Eachcylinder 14 also includes aspark plug 52 that is configured to ignite the air and fuel mixture that is within thecylinder 14 and push down on therespective piston 24 during the power stroke of thecylinder 14. - The
vehicle 10 includes acontroller 54, which may be a powertrain control unit (PCU). While illustrated as one controller, thecontroller 54 may be part of a larger control system and may be controlled by various other controllers throughout thevehicle 10, such as a vehicle system controller (VSC). It should therefore be understood that thecontroller 54 and one or more other controllers can collectively be referred to as a “controller” that controls various components of thevehicle 10 in response to signals from various sensors to control functions such as, shutting down one or more of thecylinders 14 of theengine 12 during a skip-fire mode, selecting or scheduling shifts of a vehicle transmission, adjusting the air-fuel mixture being delivered to theengine 12, etc. - The
controller 54 may include a microprocessor or central processing unit (CPU) that is in communication with various types of computer readable storage devices or media. Computer readable storage devices or media may include volatile and nonvolatile storage in read-only memory (ROM), random-access memory (RAM), and keep-alive memory (KAM), for example. KAM is a persistent or non-volatile memory that may be used to store various operating variables while the CPU is powered down. Computer-readable storage devices or media may be implemented using any of a number of known memory devices such as PROMs (programmable read-only memory), EPROMs (electrically PROM), EEPROMs (electrically erasable PROM), flash memory, or any other electric, magnetic, optical, or combination memory devices capable of storing data, some of which represent executable instructions, used by thecontroller 54 in controlling theengine 12 or subcomponents of thevehicle 10. - The
controller 54 may be configured to increase or decrease the power output of theengine 12. More specifically, thecontroller 54 may be configured to increase or decrease the power output of theengine 12 by increasing or decreasing the airflow and fuel flow into eachcylinder 14. The airflow may be increased by adjusting thethrottle valve 32 towards a fully open position or decreased by adjusting the throttle valve towards a fully closed position. The fuel flow may be increased by opening thefuel injectors 50 for longer periods of time during each injection of fuel into thecylinder 14 or decreased by opening thefuel injectors 50 for shorter periods of time during each injection of fuel into thecylinder 14. Thecontroller 54 may also increase or decrease the power output of theengine 12 by either retarding or advancing the spark timing of the spark plugs 52. - A
mass airflow sensor 56 may be configured to measure the amount of air flowing into theair intake system 16, which is eventually delivered to thecylinders 14, and communicate the amount of air flowing into theair intake system 16 to thecontroller 54. Athrottle position sensor 58 may be configured to communicate the position of thethrottle valve 32 to thecontroller 54. Thecontroller 54 may also be in communication with each of the spark plugs 52, thefuel system 18, and each of thefuel injectors 50. Based on a power demand that is delivered to thecontroller 54, the controller may adjust thethrottle valve 32 position to increase or decrease airflow into thecylinders 14, adjust the timing of the spark plugs 52, and/or adjust the amount of fuel being delivered into thecylinders 14 to either increase or decrease the power output of theengine 12 to meet the power demand. The power demand may be input into thecontroller 54 by an operator of thevehicle 10 when the operator engages anaccelerator pedal 60. Under certain circumstances the power demand may be based on a presetting that is stored as control logic within thecontroller 54. For example, if the vehicle operator is not depressing theaccelerator pedal 60 and theengine 12 is on, the amount of power theengine 12 is producing may be adjusted to a preset idle value. - Also, depending on power demand or for emission control purposes, the
engine 12 may be configured to operate at a stoichiometric air-fuel mass ratio, a lean air-fuel mass ratio, or a rich air-fuel mass ratio. The air-fuel mass ratio may simply be referred to as the air-fuel ratio. Stoichiometric air-fuel mass ratio has a value of 14.7 to 1. A rich air-fuel mass ratio will be less than 14.7 to 1 and a lean air-fuel mass ration will be greater than 14.7 to 1. An air-fuel equivalence ratio (λ) has an air-fuel mass ratio that is stoichiometric when λ is equal to 1, an air-fuel mass ratio that is rich when λ is less than 1, and an air-fuel mass ratio that is lean when λ is greater than 1. The air-fuel mass ratio may be controlled, via thecontroller 54, by adjusting the amount of air and fuel flowing into thecylinders 14. - A first lambda or
oxygen sensor 62 may be disposed within theconduits 38 of theexhaust system 20 between thecylinders 14 and thefirst catalyst 40. Thefirst oxygen sensor 62 may be a universal heated exhaust gas oxygen sensor. Thefirst oxygen sensor 62 is configured to measure the amount of oxygen (O2) that is within the exhaust gas exiting thecylinder 14. Based on the measured amount oxygen in the exhaust gas, thefirst oxygen sensor 62 generates a signal (e.g., a voltage or current) that correlates with the current air-fuel equivalence ratio (λ) that theengine 12 is operating at. The signal generated by thefirst oxygen sensor 62 may indicative of a lean, stoichiometric, or rich current air-fuel equivalence ratio (λ). Thefirst oxygen sensor 62 communicates the air-fuel ratio or air-fuel equivalence ratio (λ) measurement to thecontroller 54, which provides a feedback control to thecontroller 54. The feedback control may include adjusting the air and/or fuel flowing (i.e., flow rates) into thecylinders 14 via thecontroller 54 if the air-fuel equivalence ratio (λ) measured by thefirst oxygen sensor 62 is different than the air-fuel equivalence ratio (λ) that is being commanded to theengine 12. More specifically, the feedback control may include adjusting the air and/or fuel flowing into thecylinders 14 to drive the air-fuel equivalence ratio (λ) that is being measured by thefirst oxygen sensor 62 toward the air-fuel equivalence ratio (λ) that is being commanded to theengine 12. - A second lambda or
oxygen sensor 64, which has the same functionality as thefirst oxygen sensor 62, may be disposed within theconduits 38 of theexhaust system 20 between thefirst catalyst 40 and thesecond catalyst 42. Thesecond oxygen sensor 64 is utilized to determine the efficiency at which thefirst catalyst 40 reduces the amount of emissions within the exhaust gas. Thesecond oxygen sensor 64 is configured to communicate a signal that correlates with the measured air-fuel equivalence ratio (λ) of the exhaust gas back to thecontroller 54, after the exhaust gas has passed through thefirst catalyst 40. Aparticulate sensor 66 may be disposed within theconduits 38 of theexhaust system 20 between thesecond catalyst 42 and theparticulate filter 44. Theparticulate sensor 66 is configured to measure the amount of particulate matter within the exhaust gas and communicate the measurement to thecontroller 54 in the form of a signal (e.g., a voltage or current). - One or
more temperature sensors 63 may configured to measure the temperature of thefirst catalyst 40 and/or thesecond catalyst 42. Thetemperature sensors 63 are configured to communicate a signal that correlates with a measured temperature of thefirst catalyst 40 and/or thesecond catalyst 42 back to thecontroller 54. - The
engine 12 also includes an oil pan orsump 68. Anoil pump 70 is configured to direct oil out of thesump 68 and towards various lubrication points 72, such as any of the bearings, journals, valve stems, or any of the other moving parts within theengine 12. Apressure sensor 74 may be configured to measure the pressure of the oil that is being output from theoil pump 70. Thepressure sensor 74 may then communicate the oil pressure to thecontroller 54. Anoil level sensor 76 may be configured to measure the level of the oil within the pan orsump 68. Theoil level sensor 76 may then communicate the level of the oil to thecontroller 54. - Referring to
FIG. 2 , theengine 12 is illustrated as an eight-cylinder engine that includes a first bank 78 of fourcylinders 14 and a second bank 80 of fourcylinders 14. The first bank 78 of cylinders includes anexhaust system 20 that is configured to channel the exhaust gas away from the first bank 78 of cylinders only. The second bank 80 of cylinders includes anexhaust system 20 that is configured to channel the exhaust gas away from the second bank 80 of cylinders only. AlthoughFIG. 2 illustrates an eight-cylinder engine that includes two banks of cylinders where each bank has itsown exhaust system 20, it should be understood that theengine 12 may include two or more cylinders that comprise of one or more banks of cylinders where each bank of cylinders may include a separate exhaust system. - The
engine 12 may be a variable displacement engine or a skip-fire engine that may be controlled to shut down or deactivate one ormore cylinders 14 while theengine 12 is operating, resulting in theengine 12 being powered by less than all thecylinders 14. Shutting down or deactivating a specific cylinder 14 a during skip-fire mode requires shutting down or deactivating theair intake valve 36,exhaust valve 48,spark plug 52, and thefuel injector 50. Theengine 12 may be referred to as operating in a skip-fire mode when being powered by less than all of thecylinders 14. Thecylinders 14 may be shut down or deactivated in any known pattern to increase the fuel efficiency when conditions are such that theengine 12 may effectively operate in the skip-fire mode to increase fuel efficiency without disturbing the driving requirements of the vehicle operator (e.g., when the number of cylinders can be reduced without reducing the speed of the vehicle). However, it may be desirable to shut down or deactivate thecylinders 14 based on the position of thecylinders 14 in order to directionally equalize the forces that are being transferred to thecrankshaft 26 from thepistons 24. Furthermore, which of thecylinders 14 are shut down or deactivated and which of thecylinders 14 are operating may always be changing or rotating when in the skip-fire mode, which may also help to directionally equalize the forces that are being transferred to thecrankshaft 26 from thepistons 24. - Referring to
FIGS. 3A-3C amechanism 82 that is configured to deactivate theair intake valves 36 andexhaust valves 48 in the variable displacement/skip-fire engine 12 is illustrated. During a skip-fire mode, if aparticular cylinder 14 is shut down or deactivated, both theair intake valve 36 and theexhaust valve 48 of thatparticular cylinder 14 will also be deactivated (i.e., theair intake valve 36 andexhaust valve 48 will be in closed positions and disabled from transitioning to opened positions). Themechanism 82 includes adeactivation arm 84 and alocking pin 86. The lockingpin 86 is configured to advance and engage aprotrusion 88 that extends outward from thedeactivation arm 84. The lockingpin 86 is also configured to retract and disengage from theprotrusion 88 that extends outward from thedeactivation arm 84. Astem valve 90 is secured to an opposing side of thedeactivation arm 84 relative to theprotrusion 88. Thestem valve 90 may be representative of both theair intake valves 36 and theexhaust valves 48. - The
deactivation arm 84 will rotate about afirst pivot 92 when engaged by acamshaft 94 while the lockingpin 86 is engaging theprotrusion 88. Rotation of thedeactivation arm 84 about thefirst pivot 92 allows thestem valve 90 to transition between a closed position (seeFIG. 3A ) and an opened position (seeFIG. 3B ). Thestem valve 90 as depicted inFIGS. 3A and 3B has not been deactivated (i.e., thestem valve 90 will transition between the opened and closed positions in response to rotation of the camshaft 94). Thedeactivation arm 84 will rotate about asecond pivot 96, which rotatably secures thedeactivation arm 84 to thestem valve 90, when engaged by thecamshaft 94 while the lockingpin 86 is disengaged from theprotrusion 88. Rotation of thedeactivation arm 84 about thesecond pivot 96 results in thestem valve 90 remaining in the closed position regardless of the position of thecamshaft 94 and the position of the deactivation arm 84 (seeFIG. 3C ). Thestem valve 90 as depicted inFIG. 3C has been deactivated (i.e., thestem valve 90 will remain in the closed position and will not transition between the opened and closed positions in response to engagement between the deactivation arm and the camshaft 94). - The locking
pin 86 may be advanced and retracted by a pressurized fluid. Theoil pump 70 may be configured to deliver pressurized oil to afirst chamber 98 that is located on a first side of the lockingpin 86 in order to advance the lockingpin 86 such that the lockingpin 86 engages theprotrusion 88. Theoil pump 70 may also be configured to deliver pressurized oil to asecond chamber 100 that is located on a second side of the lockingpin 86 in order to retract the lockingpin 86 such that the lockingpin 86 disengages from theprotrusion 88. A firstfluid valve 102 may be disposed within a conduit between theoil pump 70 and thefirst chamber 98. Asecond valve 104 may be disposed within a conduit between the oil pump in thesecond chamber 100. The pressurized fluid is delivered to thefirst chamber 98 when thefirst valve 102 is open and thesecond valve 104 is closed. The pressurized fluid is delivered to thesecond chamber 100 and when thefirst valve 102 is closed and thesecond valve 104 is open. When thefirst valve 102 is opened and thesecond valve 104 is closed, the lockingpin 86 is advanced (seeFIGS. 3A and 3B ) and thestem valve 90 may transition between the opened and closed positions (i.e., thestem valve 90 has not been deactivated). When thefirst valve 102 is closed and thesecond valve 104 is opened, the lockingpin 86 is retracted (seeFIG. 3C ), thestem valve 90 remains in the closed position, and thestem valve 90 cannot transition to the opened position (i.e., thestem valve 90 has been deactivated). - The
controller 54 may be configured to open and close thefirst valve 102 and thesecond valve 104 to either advance or retract the locking to pin 86 to respectivley activate or deactivate thestem valve 90. More specifically, thecontroller 54 may be configured to activate or deactivate theair intake valve 36 and theexhaust valve 48 of aparticular cylinder 14 by utilizing themechanism 82 depicted inFIGS. 3A-3C , depending on whether theengine 12 is operating in a mode where theparticular cylinder 14 is activated or operating in a skip-fire mode that requires theparticular cylinder 14 to be shut down or deactivated. When theair intake valve 36 and theexhaust valve 48 of aparticular cylinder 14 are deactivated, theparticular cylinder 14 is also deactivated. Each valve (air intake valve 36 and exhaust valve 48) for eachcylinder 14 may include an associatedmechanism 82 for disabling the particular valve. Themechanism 82 depicted inFIGS. 3A-3C is not intended to be limiting. Theengine 12 may be a variable displacement/skip-fire engine where the valves of a particular cylinder (and therefore the cylinder itself) may be deactivated by any method known in the art. - Referring to
FIGS. 4A and 4B , a flowchart of acontrol method 200 for controlling the variable displacement or skip-fireinternal combustion engine 12 is illustrated. Themethod 200 may be stored as control logic and/or an algorithm within thecontroller 54. Thecontroller 54 may be programmed to implement themethod 200 by controlling the various components of thevehicle 10. Themethod 200 begins atblock 202 where it is determined if theengine 12 has been started. If the engine has not been started, themethod 200 recycles back to the beginning ofblock 202. If theengine 12 has been started, themethod 200 moves on to block 204 where it is determined if a temperature of a catalyst (e.g., thefirst catalyst 40 and/or the second catalyst 42) is less than a first threshold. The first threshold may be a light-off temperature of the catalyst. The catalyst operates most efficiently (i.e., reduces the maximum amount of emissions within the exhaust gas of the engine 12) at temperatures that are at or above the light-off temperature. - If the temperature the catalyst is not less than the first threshold (i.e., if the temperature of the catalyst is greater than or equal to the first threshold) the
method 200 moves on to block 206 where theengine 12 is operated according to normal operating conditions. Normal operating conditions may include operating all of thecylinders 14 of theengine 12 or operating theengine 12 in the skip-fire mode if conditions are such that it is desirable to operate in the skip-fire mode. Returning to block 204, if the temperature of the catalyst is less than the first threshold, themethod 200 moves on to block 208 where a first of thecylinders 14 is operated alone (i.e., the first of thecylinders 14 is operated while the remainder of thecylinders 14 are shut down or deactivated) to increase the temperature of the catalyst toward the first threshold. - Next, the
method 200 moves on to block 210 where it is determined if the temperature of the catalyst has increased to a value that is greater than or equal to the first threshold while the first of thecylinders 14 is operated alone. If the temperature of the catalyst has increased to a value that is greater than or equal to the first threshold while the first of thecylinders 14 is operated alone, themethod 200 moves on to block 206 where theengine 12 is operated according to the normal operating conditions, which may entail initiating operation of all of the remainder of thecylinders 14 or a portion of the remainder of thecylinders 14 if conditions are such that it is desirable to operate in the skip-fire mode. If the temperature of the catalyst has not increased to a value that is greater than or equal to the first threshold while the first of thecylinders 14 is operated alone (i.e., if the temperature the catalyst remains less than the first threshold), themethod 200 moves on to block 212. - At
block 212, it is determined if the temperature of a second of thecylinders 14 of theengine 12 has increased to a value that is greater than a second threshold, while the first of thecylinders 14 is being operated alone. The second threshold may correspond to a temperature at which initiating operation of the second of thecylinders 14 will decrease the time required to the heat the catalyst to the first threshold without increasing emissions or without increasing emissions to by value that is greater than a tolerable range. The second of thecylinders 14 may become heated via conduction through theengine block 22 while the first of thecylinders 14 is being operated alone. The second of thecylinders 14 may be adjacent or next to the first of the ofcylinders 14 such that heat transfer via conduction through theengine block 22 is increased or maximized. The temperature of the second of thecylinders 14 may be determined by a temperature sensor that is in contact with the second of thecylinders 14. The temperature sensor may then communicate the temperature of the second of thecylinders 14 to thecontroller 54. Alternatively, the temperature of the second of thecylinders 14 may be estimated based on a known or an estimated heat transfer between the first of thecylinders 14 and the second of thecylinders 14 that occurs over a period to time to heat thesecond cylinder 14 to a temperature that is greater than the second threshold while the first of thecylinders 14 is operating alone. The processes that are occurring inblocks - If the temperature of the second of the
cylinders 14 has not increased to a value that is greater than the second threshold, while the first of thecylinders 14 is being operated alone, the method recycles back to block 208 and eventually to block 210 and/or block 212. If the temperature of the second of thecylinders 14 has increased to a value that is greater than the second threshold, themethod 200 moves on to block 214, where operation of the second of thecylinders 14 is initiated such that the first and the second of thecylinders 14 of theengine 12 are operated alone (i.e., the first and the second of thecylinders 14 are operated while the remainder of thecylinders 14 are shut down or deactivated) to increase the temperature of the catalyst toward the first threshold. - Next, the
method 200 moves on to block 216 where it is determined if the temperature of the catalyst has increased to a value that is greater than or equal to the first threshold while the first and the second of thecylinders 14 are operated alone. If the temperature of the catalyst has increased to a value that is greater than or equal to the first threshold while the first and the second of thecylinders 14 are operated alone, themethod 200 moves on to block 206 where theengine 12 is operated according to the normal operating conditions, which may entail initiating operation of all of the remainder of thecylinders 14 or a portion of the remainder of thecylinders 14 if conditions are such that it is desirable to operate in the skip-fire mode. If the temperature of the catalyst has not increased to a value that is greater than or equal to the first threshold while the first of thecylinders 14 is operated alone (i.e., if the temperature the catalyst is less than the first threshold), themethod 200 moves on to block 218. - At
block 218, it is determined if the temperature of a third of thecylinders 14 of theengine 12 has increased to a value that is greater than a third threshold, while the first and the second of thecylinders 14 are being operated alone. The third threshold may correspond to a temperature at which initiating operation of the third of thecylinders 14 will decrease the time required to the heat the catalyst to the first threshold without increasing emissions or without increasing emissions by a value that is greater than a tolerable range. The third of thecylinders 14 may become heated via conduction through theengine block 22 while the first and the second of thecylinders 14 are being operated alone. The third of thecylinders 14 may be adjacent or next to the first and/or the second of the ofcylinders 14 such that heat transfer via conduction through theengine block 22 is increased or maximized. The temperature of the third of thecylinders 14 may be determined by a temperature sensor that is in contact with the third of thecylinders 14. The temperature sensor may then communicate the temperature of the third of thecylinders 14 to thecontroller 54. Alternatively, the temperature of the third of thecylinders 14 may be estimated based on a known or an estimated heat transfer between the first and/or the second of thecylinders 14 and the third of thecylinders 14 that occurs over a period to time to heat thethird cylinder 14 to a temperature that is greater than the third threshold while the first and the second of thecylinders 14 are operating alone. The processes that are occurring inblocks - If the temperature of the third of the
cylinders 14 has not increased to a value that is greater than the third threshold, while the first and the second of thecylinders 14 are being operated alone, themethod 200 recycles back to block 214 and eventually to block 216 and/or block 218. If the temperature of the third of thecylinders 14 has increased to a value that is greater than the third threshold, themethod 200 moves on to block 220, where operation of the third of thecylinders 14 is initiated such that the first, the second, and the third of thecylinders 14 of theengine 12 are operated alone (i.e., the first, the second, and the third of thecylinders 14 are operated while the remainder of thecylinders 14 are shut down or deactivated) to increase the temperature of the catalyst toward the first threshold. - Next, the
method 200 moves on to block 222 where it is determined if the temperature of the catalyst has increased to a value that is greater than or equal to the first threshold while the first, the second, and the third of thecylinders 14 are operated alone. If the temperature of the catalyst has increased to a value that is greater than or equal to the first threshold while the first, the second, and the third of thecylinders 14 are operated alone, themethod 200 moves on to block 206 where theengine 12 is operated according to the normal operating conditions, which may entail initiating operation of all of the remainder of thecylinders 14 or a portion of the remainder of thecylinders 14 if conditions are such that it is desirable to operate in the skip-fire mode. If the temperature of the catalyst has not increased to a value that is greater than or equal to the first threshold while the first, second, and third of thecylinders 14 are operated alone, themethod 200 may recycle back to block 220. Alternative, if the temperature of the catalyst has not increased to a value that is greater than or equal to the first threshold while the first, second, and third of thecylinders 14 are operated alone, themethod 200 may beginoperation addition cylinders 14, similar to the initiating of operation of the second and third of the cylinders 14 (e.g., adjacent cylinders may be brought into operation once they have reach a temperature at which initiating operation of thecylinders 14 will decrease the time required to the heat the catalyst to the first threshold without increasing emissions or without increasing emissions by a value that is greater than a tolerable range). - The order at which operation of the
cylinders 14 is initiated, after starting theengine 12 to heat the catalyst, may be based on several alternative factors. For example, alternatively to initiating the operation of thecylinders 14 in an order that is based on the temperature of thecylinders 14, as described according tomethod 200, the operation of thecylinders 14 may be initiated in an order that ranges from which ofcylinders 14 is closest tocatalyst 40 along a path of theexhaust conduit 38 to which of thecylinders 14 is furthest from thecatalyst 40 along the path of the exhaust conduit 38 (e.g., thefirst cylinder 14 is closer to the catalyst than the second andthird cylinders 14, while thesecond cylinder 14 is closer to thecatalyst 40 than the third cylinder 40). Stated in other terms, a distance from the first of the plurality ofcylinders 14 to thecatalyst 40 along the exhaust conduit orpipe 38 may be less than a distance from each of a remainder of the plurality ofcylinders 14 to thecatalyst 40 along the exhaust conduit orpipe 38, and a distance from the second of the plurality ofcylinders 14 to thecatalyst 40 along the exhaust conduit orpipe 38 may be less than a distance from each of a remainder of the plurality ofcylinders 14 to thecatalyst 40 along the exhaust conduit orpipe 38, other than the first of thecylinders 14. - In another alternative, the operation of the
cylinders 14 may be initiated in an order that ranges from which ofcylinders 14 produces a stream of exhaust gas that has an area of distribution on a front face of thecatalyst 40 that is largest to which ofcylinders 14 produces a stream of exhaust gas that has an area of distribution on the front face of thecatalyst 40 that is the smallest. as opposed to initiating the operation of thecylinders 14 in an order that is based on the temperature of thecylinders 14, as described according tomethod 200. For example, thefirst cylinder 14 may produce a stream of exhaust gas that has an area of distribution on the front face of thecatalyst 40 that is larger than the areas of distribution on the front face of thecatalyst 40 from the streams of exhaust gas produced by the remainder of thecylinders 14, while thesecond cylinder 14 may produce a stream of exhaust gas that has an area of distribution on the front face of thecatalyst 40 that is larger than the areas of distribution on the front face of thecatalyst 40 from the streams of exhaust gas produced by the remainder of thecylinders 14, other than the first of thecylinders 14. - In yet another alternative, the operation of the
cylinders 14 may be initiated inmethod 200 in an order that ranges from which ofcylinders 14 produces the least amount of emissions or particulate matter to which ofcylinders 14 produces largest amount of emissions or particulate matter, as opposed to initiating the operation of thecylinders 14 in an order that is based on the temperature of thecylinders 14, as described according tomethod 200. This may be determined by operating eachcylinder 14 separately and recording the emissions produced by each cylinder via the first lambda oroxygen sensor 62 or recording the amount of particulate matter produced by each cylinder via theparticulate sensor 66. - The
method 200 may be employed separately by individual banks of cylinders 14 (e.g., first bank 78 and second bank 80 of cylinders 14) if theengine 12 includes multiple banks of cylinders where each bank has a separate exhaust system that includes a separate catalyst or catalytic converter. It should be understood that the flowchart depicted inFIGS. 4A and 4B is for illustrative purposes only and that themethod 200 should not be construed as limited to the flowchart inFIGS. 4A and 4B . Some of the steps of themethod 200 may be rearranged while others may be omitted entirely. - Referring to
FIG. 5 , agraph 300 comparing the difference between the total emissions produced when asingle cylinder 14 of anengine 12 is utilized to heat thecatalyst 40 to the light-off temperature and the total emissions produced when all of thecylinders 14 of theengine 12 are utilized to heat thecatalyst 40 to the light-off temperature is illustrated.Line 302 represents the temperature of thecatalyst 40 over time when all of thecylinders 14 of theengine 12 are utilized to heat thecatalyst 40 to the light-off temperature after a cold start of theengine 12 andline 304 represents the rate at which emissions are being expelled from theexhaust system 20 into the ambient air when all of thecylinders 14 of theengine 12 are utilized to heat thecatalyst 40 to the light-off temperature after a cold start of theengine 12.Line 306 represents the temperature of thecatalyst 40 over time when one of thecylinders 14 of theengine 12 is utilized to heat thecatalyst 40 to the light-off temperature after a cold start of theengine 12 andline 308 represents the rate at which emissions are being expelled from theexhaust system 20 into the ambient air when one of thecylinders 14 of theengine 12 is utilized to heat thecatalyst 40 to the light-off temperature after a cold start of theengine 12. - When all the
cylinders 14 are utilized to heat thecatalyst 40 to the light-off temperature Tlight_off, thecatalyst 40 reaches the light-off temperature Tlight_off at time t1. When one of thecylinders 14 is utilized to heat thecatalyst 40 to the light-off temperature Tlight_off, the catalyst reaches the light-off temperature Tlight_off at time t2, which occurs after time t1. The total amount of emissions produced when all of thecylinders 14 are utilized to heat thecatalyst 40 to the light-off temperature Tlight_off is represented by the area underline 304 between times t0 and t1. The total amount of emissions produced when one of thecylinders 14 is utilized to heat thecatalyst 40 to the light-off temperature Tlight_off is represented by the area underline 308 between times t0 and t2, which is smaller than the area underline 304 between times t0 and t1. Therefore, it can be understood from thegraph 300 that decreasing the number ofcylinders 14 of theengine 12 to heat thecatalyst 40 to the light-off temperature Tlight_off results in reducing the total number of emissions produced by theengine 12 that are expelled from theexhaust system 20 into the ambient air. However, decreasing the number ofcylinders 14 of theengine 12 to heat the catalyst to the light-off temperature Tlight off also results increasing the time period required to heat thecatalyst 40 to the light-off temperature Tlight_off. Therefore, the number ofcylinders 14 that are utilized to heat thecatalyst 40 to the light-off temperature Tlight_off may be adjusted depending on whether or not the goal is to reduce total amount of emissions while heating thecatalyst 40 to the light-off temperature Tlight_off or to reduce the time period required to heat thecatalyst 40 to the light-off temperature Tlight_off. -
FIG. 6 illustrates an exhaust gas distribution over afront face 400 of thecatalyst 40. Each stream of exhaust gas from eachcylinder 14 has an area of distribution on thefront face 400 of thecatalyst 40.Area 402 represents the largest area of distribution of exhaust gas, which is produced by a first cylinder,area 404 represents the second largest area of distribution of exhaust gas, which is produced by a second cylinder,area 406 represents the third largest and second smallest area of distribution of exhaust gas, which is produced by a third cylinder, andarea 408 represents the smallest area of distribution of exhaust gas, which is produced by a fourth cylinder. As previously stated, themethod 200 may be configured to initiate operation of thecylinders 14 in an order that ranges from which of thecylinders 14 produces a stream of exhaust gas that has an area of distribution on thefront face 400 of thecatalyst 40 that is largest to which ofcylinders 14 produces a stream of exhaust gas that has an area of distribution of exhaust gas on the front face of thecatalyst 40 that is the smallest. Therefore, themethod 200 may initiate operations of thecylinders 14 in an order that starts with thefirst cylinder 14, followed by thesecond cylinder 14, followed by thethird cylinder 14, and ending with thefourth cylinder 14. - It should be understood that the designations of first, second, third, fourth, etc. for cylinders, valves, sensors, or any other state, or condition described herein may be rearranged in the claims so that they are in chronological order with respect to the claims.
- The words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the disclosure. As previously described, the features of various embodiments may be combined to form further embodiments that may not be explicitly described or illustrated. While various embodiments could have been described as providing advantages or being preferred over other embodiments or prior art implementations with respect to one or more desired characteristics, those of ordinary skill in the art recognize that one or more features or characteristics may be compromised to achieve desired overall system attributes, which depend on the specific application and implementation. As such, embodiments described as less desirable than other embodiments or prior art implementations with respect to one or more characteristics are not outside the scope of the disclosure and may be desirable for particular applications.
Claims (20)
1. A vehicle comprising:
an internal combustion engine having a plurality of cylinders;
a conduit configured to channel exhaust gas away from the cylinders and to a catalyst; and
a controller programmed to, in response to starting the engine and a temperature of the catalyst being less than a threshold, operate a first of the plurality of cylinders alone followed by operating the first and a second of the plurality of cylinders alone to increase the temperature of the catalyst toward the threshold.
2. The vehicle of claim 1 , wherein the controller is further programmed to, in response to a temperature of the second of the plurality of cylinders exceeding a second threshold while the first of the plurality of cylinders is operating alone, initiate operation of the second of the plurality of cylinders in conjunction with the first of the plurality of cylinders to increase the temperature of the catalyst toward the threshold.
3. The vehicle of claim 2 , wherein the second of the plurality of cylinders is adjacent to the first of the plurality of cylinders.
4. The vehicle of claim 2 , wherein the controller is further programmed to, in response to a temperature of a third of the plurality of cylinders exceeding a third threshold while the first and the second of the plurality of cylinders are operating alone to increase the temperature of the catalyst, initiate operation of the third of the plurality of cylinders in conjunction with the first and the second of the plurality of cylinders to increase the temperature of the catalyst toward the threshold.
5. The vehicle of claim 4 , wherein the third of the plurality of cylinders is adjacent to the first of the plurality of cylinders.
6. The vehicle of claim 1 , wherein the threshold is a light-off temperature of the catalyst.
7. The vehicle of claim 6 , wherein the controller is further programmed to, in response the temperature of the catalyst exceeding the light-off temperature, initiate operation of a remainder of the plurality of cylinders.
8. The vehicle of claim 1 , wherein a distance from the first of the plurality of cylinders to the catalyst along the conduit is less than a distance from each of a remainder of the plurality of cylinders to the catalyst along the conduit, and a distance from the second of the plurality of cylinders to the catalyst along the conduit is less than the distance from each of the remainder of the plurality of cylinders to the catalyst along the conduit other than the distance from the first of the plurality of cylinders to the catalyst along the conduit.
9. The vehicle of claim 1 , wherein an area of distribution of exhaust gas from the first of the plurality of cylinders on a front face of the catalyst is greater than an area of distribution of exhaust gas from each of a remainder of the plurality of cylinders on the front face of the catalyst, an area of distribution of exhaust gas from the second of the plurality of cylinders on the front face of the catalyst is greater than the area of distribution of exhaust gas from each of the remainder of the plurality of cylinders on the front face of the catalyst other than the area of distribution of exhaust gas from the first of the plurality of cylinders on the front face of the catalyst.
10. The vehicle of claim 1 , wherein the emission gases produced by the first of the plurality of cylinders is less than the emission gases produced by each of the remainder of the plurality of cylinders, and the emission gases produced by the second of the plurality of cylinders is less than the emission gases produced by each of the remainder of the plurality of cylinders, other than the emission gases produced by the first of the plurality of cylinders.
11. A method of heating a catalyst in a vehicle comprising:
in response to starting an engine and a temperature of the catalyst being less than a threshold,
operating a first of a plurality of cylinders in the engine alone to produce exhaust gas to increase the temperature of the catalyst toward the threshold, and
operating the first and a second of the plurality of cylinders in the engine alone, after operating the first cylinder alone, to produce exhaust gas to increase the temperature of the catalyst toward the threshold, wherein the second cylinder is adjacent to the first cylinder.
12. The method of claim 11 further comprising:
in response to a temperature of the second of the plurality of cylinders exceeding a second threshold while the first of the plurality of cylinders is operating alone, initiate operating the second of the plurality of cylinders in conjunction with the first of the plurality of cylinders to increase the temperature of the catalyst toward the threshold.
13. The method of claim 12 further comprising:
in response to a temperature of a third of the plurality of cylinders exceeding a third threshold while the first and the second of the plurality of cylinders are operating alone to increase the temperature of the catalyst, initiate operation of the third of the plurality of cylinders in conjunction with the first and the second of the plurality of cylinders to increase the temperature of the catalyst toward the threshold, wherein the third cylinder is adjacent to the first cylinder.
14. The method of claim 11 , wherein the threshold is a light-off temperature of the catalyst.
15. The method of claim 14 further comprising:
in response to the temperature of the catalyst exceeding the light-off temperature, initiate operating a remainder of the plurality of cylinders.
16. A vehicle comprising:
an internal combustion engine having first and second banks of cylinders;
an exhaust pipe configured to channel exhaust gas away from the first bank of cylinders and to a catalytic converter; and
a controller programmed to, in response to starting the engine and a temperature of the catalytic converter being less than a threshold, operate a first cylinder from the first bank of cylinders alone followed by operating the first cylinder and a second cylinder from first bank of cylinders alone to increase the temperature of the catalytic converter toward the threshold.
17. The vehicle of claim 16 , wherein second cylinder is adjacent to the first cylinder.
18. The vehicle of claim 16 further comprising:
a second exhaust pipe configured to channel exhaust gas away from the second bank of cylinders and to a second catalytic converter, and wherein the controller is further programmed to, in response to starting the engine and a temperature of the second catalytic converter being less than the threshold, operate a first cylinder from the second bank of cylinders alone followed by operating the first cylinder and a second cylinder from second bank of cylinders alone to increase the temperature of the second catalytic converter toward the threshold.
19. The vehicle of claim 18 , wherein second cylinder from second bank of cylinders is adjacent to the first cylinder from second bank of cylinders.
20. The vehicle of claim 16 , wherein the threshold is a light-off temperature of the catalytic converter.
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