US20190338710A1

US20190338710A1 - Air flow management strategies for a diesel engine

Info

Publication number: US20190338710A1
Application number: US16/071,142
Authority: US
Inventors: James E. McCarthy, Jr.; Douglas J. Nielsen
Original assignee: Eaton Intelligent Power Ltd
Current assignee: Eaton Intelligent Power Ltd
Priority date: 2016-01-19
Filing date: 2017-01-19
Publication date: 2019-11-07
Also published as: WO2017127587A1; US20180106204A1; DE112017000256T5; DE112017000250T5; WO2017127585A1; US10801430B2; CN108474308A; CN108474308B

Abstract

A multiple cylinder diesel engine comprising an intake valve and an exhaust valve for each of the cylinders; an intake manifold for distributing intake gases across the cylinders; an exhaust manifold; intake gas control devices configured to adjust the contents of the intake manifold; a valve control system connected to deactivate the intake and exhaust valves for a selected cylinder of the diesel engine; and a fuel injection control system connected to selectively deactivate fuel injection to the selected cylinder while increasing fuel to firing cylinders, wherein the diesel engine enters a cylinder deactivation mode in a selected cylinder whereby the valve control system deactivates the respective intake valve and the respective exhaust valve for the selected cylinder while continuing to fire other cylinders of the multiple cylinders, and the fuel injection control system deactivates fuel injection to the selected cylinder while adjusting fuel to the firing other cylinders.

Description

FIELD

This application relates to air flow management strategies for a diesel engine in cylinder deactivation mode.

BACKGROUND

Cylinder deactivation (“CDA”) comprises the deactivation of intake valve, exhaust valve, and fueling for a given cylinder. CDA improves fuel economy at low load and idle by reducing losses affiliated with the otherwise low use cylinders. When using CDA on come cylinders, the normally operating combustion cylinders can have their fuel adjusted to make up for the torque missing from the CDA cylinders.

SUMMARY

The methods disclosed herein overcome the above disadvantages and improves the art by way of providing systems and techniques to adjust the air to fuel ratio (“AFR”) of intake gas supplied to a diesel engine. A diesel engine cylinder deactivation system can comprise a multiple cylinder diesel engine comprising a respective intake valve and a respective exhaust valve for each of the multiple cylinders; an intake manifold for distributing intake gases across the cylinders; an exhaust manifold for receiving exhaust gases from the cylinders; a first intake gas control device coupled to the intake manifold and configured to adjust the contents of the intake manifold; a second intake gas control device coupled to the intake manifold and configured to adjust the contents of the intake manifold; a valve control system connected to selectively deactivate a respective intake valve and a respective exhaust valve for a selected cylinder of the multiple cylinder diesel engine; and a fuel injection control system connected to selectively deactivate fuel injection to the selected cylinder while increasing fuel to firing cylinders, wherein the multiple cylinder diesel engine is configured to enter a cylinder deactivation mode in a selected cylinder of the multiple cylinders whereby the valve control system deactivates the respective intake valve and the respective exhaust valve for the selected cylinder while continuing to fire other cylinders of the multiple cylinders, and the fuel injection control system deactivates fuel injection to the selected cylinder while adjusting fuel to the firing other cylinders.
Additional objects and advantages will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the disclosure. The objects and advantages will also be realized and attained by means of the elements and combinations particularly pointed out in the appended claims.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the claimed invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a schematic for an engine system.

FIG. 2 shows a schematic for a variable valve actuator.

FIG. 3 shows a computer control network for the engine system.

FIG. 4 shows a six-cylinder engine comprising a turbine linked to a compressor to form a turbocharger.

FIGS. 5-8 show two boost devices attached to a 6 cylinder engine.

FIGS. 9-14 show flow charts with examples of engine operation.

DETAILED DESCRIPTION

Reference will now be made in detail to the examples which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. Directional references such as “left” and “right” are for ease of reference to the figures. Fluids in this disclosure can comprise a variety of compositions, including fresh or ambient air, exhaust gas, other combustion gases, vaporized fuel, among others. This disclosure primarily focusses on diesel engine operation, but aspects of the disclosure can be applied to other fueled engines and engine systems, including those fueled by biofuels and other petroleum products such as gasoline, and including hybrid-electric vehicles. Heavy-duty, light-duty, and medium-duty vehicles can benefit from the techniques disclosed herein. Hybrid vehicles and vehicles such as buses that have start/stop/load duty cycles can also benefit from the disclosure.
Turning to FIG. 1, a schematic for an engine system 10 is shown. An engine 100 comprises 6 cylinders 1-6. Other numbers of cylinders can be used, but for discussion, 6 cylinders are illustrated. The cylinders 1-6 receive intake fluid, which is combustion gas, such as air, or air mixed with exhaust gas (exhaust gas recirculation “EGR”), from the intake manifold 103. An intake manifold sensor 173 can monitor the pressure, flow rate, oxygen content, exhaust gas content or other qualities of the intake fluid. The intake manifold 103 connects to intake ports 133 in the engine block to provide intake fluid to the cylinders 1-6. In a diesel engine, the intake manifold has a vacuum except when the intake manifold is boosted. CDA is beneficial, because the cylinder can be closed. Fuel efficiency is gained by not drawing the piston down against the manifold vacuum. When the cylinder is deactivated, the crankshaft 101 has less resistance from the piston, and the crankshaft can output more torque from the firing cylinders.
Fuel is injected to individual cylinders via a fuel injection controller 300. The fuel injection controller 300 can adjust the amount and timing of fuel injected in to each cylinder and can shut off and resume fuel injection to each cylinder. The fuel injection for each cylinder 1-6 can be the same or unique for each cylinder 106, such that one cylinder can have more fuel than another, and one cylinder can have no fuel injection, while others have fuel.
A user input sensor 900 can be linked to the engine system 10 to sense user inputs such as braking, acceleration, start-up mode selection, shut-down mode selection, auxiliary device activation, among others. The user selections can impact the load requirements for the engine system 10, and the power settings for the cylinders 1-6 can be adjusted in response to the user selections. The valve control by VVA controller 200 and fuel injection from fuel injection controller 300 can be tailored based on the user selections sensed by user input sensor 900.
A variable valve actuator (VVA) 200, as shown in more detail in FIG. 2, also couples to the cylinders 1-6 to actuate intake valves 130 and exhaust valves 150. The VVA 200 can change the actuation of the intake valves 130 and exhaust valves 150 so as to open or close the valves normally, early, or late, or combinations thereof, or cease operation of the valves. VVA 200 can cooperate with a valve actuator 185, such as a hydraulic, electric, or electric solenoid system to control the intake and exhaust valves 130, 150. The engine 100 can be cam or camless, or a hybrid “cam-camless VVA.” So, the intake and exhaust valves 130, 150 can either couple to a cam system for actuation, a hydraulic rail, a latched rocker arm, other rocker arm, an electro hydraulic actuator, etc. Or a camless direct acting mechanism can selectively operate the individual valves to open and close the cylinders. The crankshaft 101 can be coupled to transfer energy between the crankshaft 101 and camshafts as by a torque transfer mechanism 115, which can comprise gear sets, belts, or other transfer mechanisms. FIG. 1 shows one intake valve 130 and one exhaust valve 150, it is possible to have two intake valves 130 and two exhaust valves 150 per each cylinder.
A computer control network is outlined in FIG. 3, and is connected to fuel injector 310 of fuel injection system and valve actuators 185 for respective intake valves and respective exhaust valves. When included, the computer control system is connected to optional EGR valve 410, variable geometry turbine 510, and intake assist device 601. The network can comprise a BUS for collecting data from various sensors, such as crankshaft sensor 107, intake manifold sensor 173, exhaust manifold sensor 175, exhaust sensor 807, catalyst sensor 809, user input sensor 900, etc. The sensors can be used for making real-time adjustments to the fuel injection timing and quantity and valve opening and closing timing. Additional functionality can be pre-programmed and stored on the memory device 1401. The additional functionality can comprise pre-programmed thresholds, tables, and other comparison and calculation structures for determining power settings for the cylinders, durations for the power settings and number and distribution cylinders at particular power settings. For example, a sensed vehicle start up selection, accessory selection, gear selection, load selection or other sensor feedback can indicate that an exhaust temperature is or will be too low. In addition to temperature thresholds for entering and exiting thermal management strategies, it is possible to apply load thresholds. Load thresholds are particularly useful for determining the power setting aspects outlined below, though it is possible to provide real-time calculations via the computer controller 1400.
Memory device 1401 is a tangible readable memory structure, such as RAM, EPROM, mass storage device, removable media drive, DRAM, hard disk drive, etc. Signals per se are excluded. The algorithms necessary for carrying out the methods disclosed herein are stored in the memory device 1401 for execution by the processor 1403. When optional variable geometry turbocharger control is implemented, the VGT control 1415 is transferred from the memory 1401 to the processor for execution, and the computer control system functions as a turbocharger controller. Likewise, the computer control system 1400 implements stored algorithms for EGR control 1414 to implement an EGR controller 400; implements stored algorithms for intake assist device control 1416 to implement intake assist controller 600; and implements stored algorithms for fuel injection control 1413 to implement fuel injection controller 300. When implementing stored algorithms for VVA control 1412, various intake valve controller and exhaust valve controller strategies are possible relating to valve timing and valve lift strategies, as detailed elsewhere in this application, and these strategies can be implemented by VVA controller 200. The processor can combine outputs from the various controllers, for example, the processor can comprise additional functionality to process outputs from VGT controller 500 and intake assist controller 600 to determine a command for valve 516. A controller area network (CAN) can be connected to appropriate actuation mechanisms to implement the commands of the processor 1403 and various controllers.
While the computer control system 1400 is illustrated as a centralized component with a single processor, the computer control system 1400 can be distributed to have multiple processors, or allocation programming to compartmentalize the processor 1403. Or, a distributed computer network can place a computer structure near one or more of the controlled structures. The distributed computer network can communicate with a centralized computer control system or can network between distributed computer structures. For example, a computer structure can be near the turbocharger 501 for VGT control 500, another computer structure can be near the EGR valves 410, 750, 850 for EGR controller 400, another computer structure can be near the intake and exhaust valves for variable valve actuator 200, yet another computer controller can be placed for fuel injection controller 300, and yet another computer controller can be implemented for intake assist controller 600. Subroutines can be stored at the distributed computer structures, with centralized or core processing conducted at computer control system 1400.
The methods disclosed herein can be implemented by a system such as outlined in FIG. 1 comprising a multiple-cylinder engine 100, the engine comprising respective reciprocating pistons 160 in the multiple cylinders 1-6, the respective reciprocating pistons connected to a crankshaft 101 for rotation of the crankshaft. A computer-controllable fuel injection system comprising a fuel controller 300 is configured to inject fuel in to the multiple cylinders. Respective computer-controllable intake valves and exhaust valves linked to VVA controller 200 are configured for opening and closing the multiple cylinders. A computer control system 1400 is part of a computer control network shown in FIG. 3 to connect to the fuel injection system and the respective intake valves and respective exhaust valves. The system comprises a processor 1403, a tangible memory device 1401, and processor-executable control algorithms for implementing the disclosed methods.
A diesel engine works by compressing intake fluid in a selected cylinder 1-6 using a piston 160. Fuel is injected into the selected cylinder, and the high heat and compression ignites the fuel. The combustion moves the piston and the resulting torque is thereby directed to the crankshaft 101. Diesel operation can be referred to as “4 stroke,” though other operation modes such as 2-stroke, 6-stroke, and 8-stroke are possible and known in the art. In 4-stroke combustion mode, the piston moves to fill the cylinder with intake fluid (stroke 1 ). At the end of stroke 1, the selected cylinder is full of intake fluid. The piston rises (stroke 2). Fuel is injected and ignites to push the piston 160 (stroke 3). The piston rises again to expel the exhaust gases out the exhaust valve (stroke 4). The intake valve is open during stroke 1 and closed during strokes 2-4, though the VVA 200 can adjust the timing of opening and closing. The exhaust valve 150 is open during stroke 4 and closed during strokes 2-4, though the VVA 200 can adjust the timing of opening and closing. Compression occurs on the second stroke, and combustion occurs on the third stroke. 6-stroke and 8-stroke techniques include additional aspects of compression and injection after the intake valve has closed and prior to the exhaust valve opening. The application will discuss 4-stroke combustion techniques in detail, but where compatible, the 4-stroke combustion techniques can be applied to augment art-recognized 6-stroke or 8-stroke combustion techniques. 2-stroke engine-braking techniques can be used with 2-, 4-, 6- or 8-stroke combustion techniques.
Exhaust gases leave cylinders through exhaust ports in the engine block. Exhaust ports communicate with an exhaust manifold 105. An exhaust manifold sensor 175 can monitor the pressure, flow rate, oxygen content, nitrous or nitric oxide (NOx) content, sulphur content, other pollution content or other qualities of the exhaust gas. Exhaust gas can power a turbine 510 of a variable geometry turbocharger (VGT) 501 or other turbocharger. The turbocharger 501 can be controlled via a turbocharger controller 500 to adjust a coupling 514 between the turbine 510 and the compressor 512. The VGT can be adjusted so as to control intake or exhaust flow rate or back pressure in the exhaust gas. A controllable valve 516 can be included to direct timing and quantity of fluid to the turbine 510 and catalyst 800 or to an optional EGR cooler 455 and EGR circuit that returns exhaust gases to the intake manifold for out-of-cylinder exhaust gas recirculation.
Exhaust gas is filtered in an aftertreatment system comprising catalyst 800. At least one exhaust sensor 807 is placed in the aftertreatment system to measure exhaust conditions such as tailpipe emissions, NOx content, exhaust temperature, flow rate, etc. The exhaust sensor 807 can comprise more than one type of sensor, such as chemical, thermal, optical, resistive, velocity, pressure, etc. A sensor linked with the turbocharger 501 can also be included to detect turbine and compressor activity.
Exhaust gas can exit the system after being filtered by the at least one catalyst 800. Or, exhaust gas can be redirected to the intake manifold 103. An optional EGR cooler 455 is included. An EGR controller 400 actuates an EGR valve 410 to selectively control the amount of EGR supplied to the intake manifold 103. EGR controller 400 can be connected to control valve 516, or the intake assist controller 600 can be connected to control the valve 516. The exhaust gas recirculated to the intake manifold 103 impacts the AFR in the cylinder. Exhaust gas dilutes the oxygen content in the intake manifold 103. Unburned fuel from the fuel doser, or unburned fuel remaining after combustion increases the fuel amount in the AFR. Soot and other particulates and pollution gases also reduce the air portion of the AFR. While fresh air brought in through the intake system 700 can raise the AFR, EGR can lower AFR, and fuel injection to the cylinders can lower the AFR further. Thus, the EGR controller 400, fuel injection controller 300 and intake assist controller 600 can tailor the air fuel ratio to the engine operating conditions by respectively operating valve 516, operating EGR valve 410, fuel injector 310, and intake assist device 610. So, adjusting the AFR to a firing cylinder can comprise one of boosting fresh air from intake system 700 to the at least one firing cylinder by controlling an intake air assist device 601, such as a supercharger, or decreasing AFR to a firing cylinder by boosting with exhaust gas recirculation to the firing cylinder. A charge air cooler 650 can optionally be included to regulate intake flow temperature. This can be done with or without augmenting with a turbocharger 501. Numerous alternative arrangements are possible for controlling AFR and other subcombinations and combinations of exhaust gas recirculation, turbocharging and supercharging are possible.
Additionally, terminating fuel injection to one or more cylinders 1-6 adjusts the AFR of exhaust gas, and deactivating a cylinder decreases the quantity of exhaust gas. Cylinder deactivation impacts the ability to power the turbine 510 to run the compressor 512. Implementing auxiliary techniques, such as engine braking, also impacts the quantity and composition of exhaust gases.
For a 6-cylinder engine, such as shown in FIG. 1, the firing order is typically 1, 5, 3, 6, 2, 4. The intake manifold 103 can comprise a shared plenum for each of the cylinders 1-6 as shown in FIGS. 1 & 8. Likewise, the exhaust manifold 105 comprises a shared plenum for each of the cylinders 1-6. Or, as drawn in FIGS. 4-7, there can be provided divisions in the intake manifold 103 and in the exhaust manifold 105 to form multiple plenums for directing gas to or from specific cylinders or sets of cylinders.
In FIG. 4, exhaust gases expelled from the engine 100 spin the turbine 510. The mechanical energy is coupled to the compressor 512. The compressor compresses intake gases 700, which can comprise fresh air, exhaust gases, or a mixture of intake and exhaust gases. The compressor 512 compresses the intake gases provided and directs it to the cylinders 1-6.
Alternative combinations of turbochargers, superchargers and plenums for intake manifold 103 and exhaust manifold 105 are shown in FIGS. 5-8. When CDA mode is implemented, it is convenient to think of the engine as having a first half and a second half. Cylinders 1, 3, 2 could be fired, in that order, or deactivated. Complementary cylinders 5, 6, 4 could be shut down, or fired in that order. Essentially, there are two engines in one block, with the cylinder sets optimized for their intended operation.
It is possible to provide one turbocharger 501 or other boost device to control AFR to one set of cylinders 1-3, and then provide a second boost device, such as supercharger 602, to the second set of cylinders 4-6 as shown in FIG. 6. A pair of turbochargers 501, 502 can be used, as shown in FIG. 5. The intake manifold 103 and the exhaust manifold 105 can comprise plenums to control flow to sets of cylinders. For example, in FIG. 4, the intake manifold has a shared intake gas from compressor 512 and divides the intake gas to individual plenums for each cylinder. Likewise, an individual plenum collects exhaust gas and gathers the exhaust gas and directs it to turbine 510.
In FIG. 5, however, intake plenums 710, 712 are specific to cylinder sets and boost devices, and so are the exhaust plenums 810, 812. The plenums 710, 712, 810, 812 can comprise physical barriers within the intake manifold and exhaust manifold. Controllable valves 750, 850 permit sharing of gases between the otherwise dedicated plenums. Ducting 751, 851 can shunt gas between plenums or the valves 750, 850 can be embedded in a wall between the plenums. Also, controlled leakage paths can be included in the plenums to permit gas to leak between plenums when the plenums are internal to one of the manifolds 103, 105.
There can be mismatch between the boost devices, such that one boost device has higher boost capacity than the other, because one cylinder set will require a different boost amount than the other cylinder set. This limits wasted capacity and wasted energy.
For one example, a first boost device comprises a turbocharger 501 and a second boost device comprises a second turbocharger 502. The compressor 512 of the first turbocharger pushes intake gas to both the second turbine 513 of the second turbocharger and to cylinders 4-6, as shown in FIG. 7A. The second turbine comprises an inner plenum 710 to segregate boost capacity to cylinders 1-3. Likewise, exhaust from cylinders 1-3 is segregated to second compressor of second turbine by plenum 810, but exhaust gas from the second turbine 511 and from cylinders 4-6 spin the first turbine 510 of turbocharger 501. Intake manifold 103 surrounds intake gas from compressor 512 and intake gas for compressor 513. Exhaust manifold 105 surrounds exhaust gas from turbine 511 and cylinders 4-6.
Alternatively, as shown in FIG. 7B, a supercharger 602 is used to boost the compressor 513 and the cylinders 1-6. As discussed more below, when the cylinders 1-3 are deactivated, then the compressor 513 is effectively blocked and intake gas is fed only to cylinders 4-6 without leaking or losses in the turbocharger. Low load and idle modes, as discussed more below are adequately boosted by the supercharger 602. The turbocharger can be spun up and used in higher load operation modes.
When in a low load or idle condition, it is difficult to fully spin up the turbine of the turbocharger, so having two smaller sized turbochargers permits one to capture available exhaust energy, while the other is shut off via a diverter, physically decoupled, or permitted to free-wheel. In low load and idle conditions, it is difficult for a turbocharger to generate enough boost to control AFR, because exhaust output is low, so using a supercharger in low load and idle conditions, to tailor AFR is desirable. It is possible to extend the range of CDA using the supercharger to control both low and high AFR, and to use the supercharger for the full operation range of the engine, while the turbo is sized and designed for cruising mode or high load, only. Such split-use permits more efficient tailoring for the reduced number of modes on the turbo.
During CDA, the captured exhaust energy is directed to the one set of cylinders. EGR can also be diverted to the one set of cylinders. The EGR dilutes the AFR, lowering it, and permits a higher combustion temperature. This reduces NOx and raises the catalyst temperature.
When high load and high boost is needed, both turbines can receive exhaust gas to power both affiliated compressors.
It is also possible to run various modes on the two engine halves, such that one half is shut down(CDA), and the other uses early or late-intake valve opening or closing (or early or late exhaust valve opening or closing) Combinations of LIVO, EIVC, EEVO, LEVC can be run on the separate halves, with the turbochargers controlling AFR appropriately for the respective mode.
Instead of adjusting the turbo map of a single turbocharger, there are now two turbochargers to adjust.
A further modification permits capture of a respective exhaust stream for a respective engine half, so that the turbine for one half captures the exhaust energy for its exhaust output. Otherwise, the turbochargers share the exhaust stream until it is desired to power one or the other of the turbines.
When one set of cylinders is in CDA mode, and the turbocharger is shut off for that set, it is possible to divert flow from the other boost device to spin up the idle turbocharger before exiting CDA. A valve can divert air from the active boost device to the intake manifold of the CDA cylinder set to ramp up the CDA set. The turbine can spin up more quickly because of the boost. Or, a valve can divert exhaust gas from the exhaust manifold to the idle turbine to spin it up and activate its compressor to help exit CDA mode. Or, diversion can be on both the intake and exhaust sides, so intake side boost is diverted to the CDA set, and exhaust gas is shared with the CDA turbine to spin it up.
FIG. 8 shows one implementation. Controllable valves 517, 518, 519, 520 can comprise butterfly or one way valves to prevent backwards leaking of boost air. When one of the boost devices is not running, due to cylinder deactivation mode or load conditions, affiliated valves can be shut to prevent boost air from leaking through the idle boost device. When the active boost device puts EGR or fresh intake air in to the shared plenum of the intake manifold 103, the controllable valves can be closed to prevent the flow from exiting the idle boost device. For example, valve 518 can be controlled to create a back-pressure in exhaust manifold 105. It can also be controlled to permit or prevent supercharger 602 from suctioning exhaust gas from the engine 100 or catalyst 800. When a lean AFR is desired, and it is permissible to introduce exhaust in to the intake manifold, the valve 518 can be controlled suction exhaust for exhaust gas recirculation. It is also possible to control the valve 518 to clean the catalyst, as is done in two-wheel or three-wheel vehicles and light duty 4-wheel vehicles. And, the valve 518 can be controlled to permit the compressor 510 to spin on its own, as by exhaust gas flowing over it, to power turbine 512. When turbine 512 is spinning, it is possible to close valves 519 & 517 to prevent leakage of boost through the supercharger 602. A one way valve 520 can be used for valve 520 so that the supercharger 602 can spin at the same time as compressor 512. Or, a controllable valve can be used, so that when supercharger is spinning, the compressor 512 is blocked.
An alternative solution divides the intake manifold 103 in two, as in FIG. 5. Each cylinder set has a dedicated plenum. Optional valves 750, 850 between the plenums 710 & 712 and 810 & 812 permit the active boost device to ramp up the idle boost device. In this situation, closing the valve 850 permits dedicated flow to power a dedicated turbine. But opening the valve 850 permits the exhaust from one cylinder set to power the turbine affiliated with the other cylinder set. Such a valve can be included in FIG. 6, also, as a way to permit the supercharger 602 to spin up the turbine 510. Controlling the valve 750 permits the compressor 513 or supercharger 602 to provide intake gas to the plenum 710 for valves 1-3 during periods of turbo-lag or when an initial spin-up of the turbine 510 is in process. Opening and closing the valves 750, 850 becomes part of the algorithms stored in EGR control 1414 and intake assist device control 1413 for execution by EGR controller 400 and intake assist controller 600. Because of the overlapping activity of these devices in this instance, the controller can be consolidated in to a single processor or subordinate processor and affiliated stored program.
Cylinder deactivation mode is very complementary to this low-leakage arrangement. When a cylinder set is deactivated, the intake valves 130 and exhaust valves 150 are closed. The cylinders block leakage between the intake manifold 103 and the exhaust manifold 105. Blocking this leakage helps spin up the turbines 510 when controlling the valve 850 in FIGS. 5 & 6. So, in FIG. 6, supercharged cylinders 4-6 can exhaust a high volume of exhaust gas and valve 850 can direct that exhaust gas to spin up turbine 510. Deactivated cylinders 1-3 block leakage of exhaust gas to plenum 710. In FIG. 5, if cylinders 1-3 are deactivated, then exhaust from cylinders 4-6 can be used through valve 850 to spin up turbine 510. Controlling the valve 850 controls how much exhaust is used for turbine 511 or for other purposes such as external EGR or aftertreatment.
In one embodiment, a multiple cylinder diesel engine comprising a respective intake valve 130 and a respective exhaust valve 150 for each of the multiple cylinders 1-6, an intake manifold 103 for distributing intake gases across the cylinders 1-6, an exhaust manifold 105 for receiving exhaust gases from the cylinders, a first intake gas control device 601 coupled to the intake manifold and configured to adjust the contents of the intake manifold 103, a second intake gas control device 601 coupled to the intake manifold 103 and configured to adjust the contents of the intake manifold 103, a valve control system connected to selectively deactivate a respective intake valve 130 and a respective exhaust valve 150 for a selected cylinder of the multiple cylinder diesel engine, and a fuel injection control system connected to selectively deactivate fuel injection to the selected cylinder while increasing fuel to firing cylinders, wherein the multiple cylinder diesel engine is configured to enter a cylinder deactivation mode in a selected cylinder of the multiple cylinders whereby the valve control system deactivates the respective intake valve 130 and the respective exhaust valve 150 for the selected cylinder while continuing to fire other cylinders of the multiple cylinders, and the fuel injection control system deactivates fuel injection to the selected cylinder while adjusting fuel to the firing other cylinders.
It is possible to use a supercharger (SC) as a low level EGR pump. EGR is pumped to the intake manifold during low level operation. Displacing intake air with EGR increases combustion temperature.
In order to meet current FTP cycles for a heavy duty engine coming up to speed, it is possible to inject more fuel to increase torque output, but this increases the exhaust output and uses too much fuel.
When using EGR in a diesel, fresh intake air is replaced with EGR during low load and idle conditions. This reduces the air-fuel ratio (AFR), which increases the heat of combustion. A small supercharger 602 can be used to direct EGR in to the intake manifold, as shown in FIG. 8. So rather than compressing fresh air for a fresh air boost, which would increase AFR, the supercharger 602 directs exhaust gas to the intake manifold to lower the AFR to make the after-treatment hotter. Combustion heat is increased, which is beneficial to the after-treatment system.
As shown in the method 1001 of FIG. 9, engine system 10 lowers AFR by spinning a turbine at block 1000 by using exhaust gases expelled from the engine to generate mechanical energy, and coupling the mechanical energy to a compressor to compress intake gases in block 1005. The intake gases are directed through an intake manifold to a plurality of cylinders in block 1010, and a cylinder is selected from the plurality of cylinders and deactivates fuel injection to the selected cylinder in block 1030, which increasing fuel injection to the firing other cylinders in block 1035 CDA is entered for the selected cylinder while continuing to fire the firing other cylinders, and expelling the exhaust gases through an exhaust manifold in block 1040.
In other embodiments, the intake gases may be directed through an intake manifold comprising one or many gas intake control devices. Expanding on block 1010, FIG. 10 comprises block 1011 where intake gases are directed to one or more gas intake control devices and then directed over the cylinders in block 1012. The gas intake control devices may be superchargers, turbochargers, or any combination of gas intake control devices, as shown for example in FIGS. 11-13. In FIG. 11, which expands on block 1010, intake gases are directed to two turbochargers in block 1013. The first turbocharger directs intake gases over the certain cylinders in block 1014 while the second turbocharger concurrently directs intake gases over certain other cylinders in block 1015. For further example, FIG. 12 expands on block 1010. Intake gases are directed to a turbocharger and a supercharger in block 1016. In block 1017, the turbocharger directs intake gases over certain cylinders, and in block 1018, the supercharger concurrently directs intake gases over certain other cylinders. Each gas intake control device may direct the intake gases over connected cylinders.
When combined with CDA, greater gains are achieved because the deactivated cylinders do not intake either fresh or EGR fluids, which increases the amount of EGR available to the active cylinders. Heat of combustion is further increased in the active cylinders as AFR decreases. The catalyst can be heated even in low load and idle conditions. This is beneficial to the lowest load conditions where the lowest AFR is applicable, because the EGR can dilute the fresh air, and the CDA can avoid intaking fresh air. For example, an expanded block 1010 from FIG. 9 is shown in FIG. 13. Intake gases are directed to a first gas intake control device in block 1019. The first gas intake control device directs intake gases over certain cylinders in block 1020. Then, the first gas intake control device directs intake gases to a second gas intake control device in block 1021.
The transition period also benefits, when the engine transitions from low load to a load that can power the turbocharger, because the supercharger can make up for the turbo-lag. Contrary to prior art, cold fresh air can be avoided even during the transition period, and hot exhaust gas can be used instead. At some point in acceleration, the CDA must be discontinued to meet load requirements, but the catalyst is heated and the turbo is spun up and ready to supply compressed air for the higher load condition.
When the engine is moved from low load to higher load conditions, a valve in the supercharger (SC) can be reversed to intake fresh air for higher AFR and higher torque output, as shown in FIG. 8. This spins up the turbocharger system for high load operation. It is possible to use the supercharger during the operation point that the turbocharger is inefficient and to use the supercharger to ramp up the output necessary to power the turbocharger.
The supercharger has dual functionality: pumping EGR and pumping fresh intake air. So, the supercharger can reduce the air pulled through the engine in EGR pump mode, but bring AFR back up quickly for high load conditions in fresh air pump mode.
Additional emissions gains are achieved by reducing AFR using EGR: instead of injecting more fuel to increase the AFR, the air is diluted via EGR. As shown in FIG. 14, which shows an expanded block 1040 from FIG. 9. Exhaust gases are directed to a gas intake control device in block 1041. Additional exhaust gases may be expelled from the engine in block 1042. Less fuel is used to meet mandatory cycle time tests, resulting in lower emissions.
Diesels have inefficient operation zones where a turbocharger is not sufficiently excited to provide boost. Transitional areas suffer turbo lag, and low load and idle conditions suffer poor air-fuel ratio (AFR).
FIGS. 1, 6 & 7B show schematics for extending the range of CDA using the supercharger 602 to control both low and high AFR, and to use the supercharger for the full operation range of the engine. A supercharger 602 is better suited for low load and idle conditions, where many heavy machinery diesels spend a majority of their operation. On-demand boosting, via an electric motor or belt driven or other CVT (continuously variable transmission), makes the supercharger the best choice for the transitional area between low load and higher loads.
When combined with cylinder deactivation (CDA), both the boost amount and the fuel amount can be tailored to the torque demand. The supercharger can be powered to lower the AFR, and reversed or ramped up or valved off EGR suction to provide boost to raise the AFR.
The turbocharger can be eliminated because the AFR tailoring by the supercharger is so efficient, that the amount of exhaust gas to power the turbocharger is limited for most of the turbo operating range. So, what exhaust gas does come out, is the correct temperature for the catalyst, and is lower in NOx due to the highly controlled AFR by the supercharger.
The CDA operation can be further combined with Late Intake Valve Closure (LIVC) or Early Intake Valve Closure (EIVC) to facilitate use of a smaller-sized engine. Without the supercharger, the fluid is compressed less, but expanded more, and the exhaust gas temperature and pressure is insufficient to power a turbo. The supercharger can boost the cylinder for high load, and keep AFR low for low load. Because the turbocharger is useless without the support of the supercharger, and the supercharger can otherwise cover the airflow demands, it is beneficial to remove the turbo altogether.
Other implementations will be apparent to those skilled in the art from consideration of the specification and practice of the examples disclosed herein. It is intended that the specification and examples be considered as exemplary only, with the true scope of the invention being indicated by the following claims.

Claims

1. A diesel engine cylinder deactivation system comprising:

a multiple cylinder diesel engine comprising a respective intake valve and a respective exhaust valve for each of the multiple cylinders;

an intake manifold for distributing intake gases across the cylinders;

an exhaust manifold for receiving exhaust gases from the cylinders;

a first intake gas control device coupled to the intake manifold and configured to adjust the contents of the intake manifold;

a second intake gas control device coupled to the intake manifold and configured to adjust the contents of the intake manifold;

a valve control system connected to selectively deactivate a respective intake valve and a respective exhaust valve for a selected cylinder of the multiple cylinder diesel engine; and

a fuel injection control system connected to selectively deactivate fuel injection to the selected cylinder while increasing fuel to firing cylinders,

wherein the multiple cylinder diesel engine is configured to enter a cylinder deactivation mode in the selected cylinder of the multiple cylinders whereby:

the valve control system deactivates the respective intake valve and the respective exhaust valve for the selected cylinder while continuing to fire other cylinders of the multiple cylinders, and

the fuel injection control system deactivates fuel injection to the selected cylinder while adjusting fuel to the firing other cylinders.

2. The system of claim 1, wherein the intake manifold is divided into intake plenums to tailor flow to the deactivated selected cylinder.

3. The system of claim 1, further comprising a first intake plenum coupled to the selected cylinder and a second intake plenum coupled to the other cylinders, wherein the first intake gas control device comprises a first turbocharger coupled to the first intake plenum, and wherein the second intake gas control device comprises a second turbocharger coupled to the second intake plenum.

4. The system of claim 1, further comprising a first intake plenum coupled to the selected cylinder and a second intake plenum coupled to the other cylinders;

wherein the first intake gas control device comprises a first turbocharger coupled to the first intake plenum;

wherein the second intake gas control device comprises a first supercharger coupled to the second intake plenum;

wherein the turbocharger is coupled to tailor fluid flow to a first set of cylinders of the multiple cylinder diesel engine and the supercharger is coupled to tailor fluid flow to a second set of cylinders of the multiple cylinder diesel engine.

5. The system of claim 1 wherein the exhaust manifold is divided in to exhaust plenums to tailor the distribution of exhaust gases from each of the multiple cylinders.

6. The system of claim 1, further comprising exhaust gas recirculation connections between the exhaust manifold and the intake manifold.

7. The system of claim 4, further comprising exhaust gas recirculation connections between the exhaust manifold and the supercharger, wherein the supercharger comprises a valve for selecting fluid flow to the intake manifold, and wherein the valve is controllable to select between exhaust gas recirculation and fresh intake air, or a combination of exhaust gas recirculation and fresh intake air.

8. The system of claim 4, wherein the supercharger is configured to pump intake gases in a first direction to boost the pressure of the intake gases in the intake manifold, and wherein the supercharger is configured to pump the intake gases in a second direction to suction the intake gases out of the intake manifold.

9. The system of claim 7, wherein the supercharger is configured to pump exhaust gas into the intake manifold.

10. The system of claim 1, wherein selected deactivation cylinders are placed with respect to the intake manifold to tailor the fluid flow to the firing cylinders.

11. A method of lowering an air to fuel ratio of a combustion engine, comprising:

spinning a turbine using exhaust gases expelled from an engine to generate mechanical energy;

coupling the mechanical energy to a compressor to compress intake gases;

directing the intake gases through an intake manifold to a plurality of cylinders;

selecting a cylinder of one of the plurality of cylinders;

deactivating fuel injection to the selected cylinder;

increasing fuel injection to firing other cylinders of the plurality of cylinders;

entering cylinder deactivation mode for the selected cylinder while continuing to fire the firing other cylinders; and

expelling the exhaust gases through an exhaust manifold.

12. The method of claim 11, wherein the intake gases comprise the exhaust gases.

13. The method of claim 11, wherein the cylinder deactivation further comprises late intake valve closure.

14. The method of claim 11, wherein the cylinder deactivation further comprises early intake valve closure.

15. The method of claim 12, wherein the intake gases are directed over the other firing cylinders.

16. The method of claim 11, wherein directing the intake gases through the intake manifold further comprises using a gas intake control device.

17. The method of claim 16, wherein directing the intake gases through the intake manifold further comprises using a plurality of gas intake control devices.

18. The method of claim 17, wherein a turbocharger directs the intake gases over certain cylinders and a second turbocharger directs the intake gases over certain other cylinders.

19. The method of claim 17 wherein a turbocharger directs the intake gases over certain cylinders and a supercharger directs the intake gases over certain other cylinders.

20. The method of claim 17 where the intake gases are directed from a first gas intake control device to at least a second gas intake control device.

21. The method of claim 16, wherein the exhaust gases are directed to the gas intake control device.

22. The method of claim 17, wherein the exhaust gases are directed to at least one of the plurality of gas intake control devices.