GB2372537A - Engine with controlled auto-ignition - Google Patents

Engine with controlled auto-ignition Download PDF

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Publication number
GB2372537A
GB2372537A GB0104336A GB0104336A GB2372537A GB 2372537 A GB2372537 A GB 2372537A GB 0104336 A GB0104336 A GB 0104336A GB 0104336 A GB0104336 A GB 0104336A GB 2372537 A GB2372537 A GB 2372537A
Authority
GB
United Kingdom
Prior art keywords
engine
charge
intake
phase
exhaust
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
GB0104336A
Other versions
GB0104336D0 (en
Inventor
Thomas Tsoi-Hei Ma
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Ford Global Technologies LLC
Original Assignee
Ford Global Technologies LLC
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Ford Global Technologies LLC filed Critical Ford Global Technologies LLC
Priority to GB0104336A priority Critical patent/GB2372537A/en
Publication of GB0104336D0 publication Critical patent/GB0104336D0/en
Publication of GB2372537A publication Critical patent/GB2372537A/en
Withdrawn legal-status Critical Current

Links

Classifications

    • 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
    • F02D13/0203—Variable control of intake and exhaust valves
    • F02D13/0207—Variable control of intake and exhaust valves changing valve lift or valve lift and timing
    • F02D13/0211—Variable control of intake and exhaust valves changing valve lift or valve lift and timing the change of valve timing is caused by the change in valve lift, i.e. both valve lift and timing are functionally related
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B1/00—Engines characterised by fuel-air mixture compression
    • F02B1/12—Engines characterised by fuel-air mixture compression with compression ignition
    • F02B1/14—Methods of operating
    • 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
    • F02D13/0261—Controlling the valve overlap
    • F02D13/0265—Negative valve overlap for temporarily storing residual gas in the cylinder
    • 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
    • F02D41/0002—Controlling intake air
    • 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
    • F02D41/30—Controlling fuel injection
    • F02D41/3011—Controlling fuel injection according to or using specific or several modes of combustion
    • F02D41/3017—Controlling fuel injection according to or using specific or several modes of combustion characterised by the mode(s) being used
    • F02D41/3035—Controlling fuel injection according to or using specific or several modes of combustion characterised by the mode(s) being used a mode being the premixed charge compression-ignition mode
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D9/00—Controlling engines by throttling air or fuel-and-air induction conduits or exhaust conduits
    • F02D9/04—Controlling engines by throttling air or fuel-and-air induction conduits or exhaust conduits concerning exhaust conduits
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M26/00—Engine-pertinent apparatus for adding exhaust gases to combustion-air, main fuel or fuel-air mixture, e.g. by exhaust gas recirculation [EGR] systems
    • F02M26/01—Internal exhaust gas recirculation, i.e. wherein the residual exhaust gases are trapped in the cylinder or pushed back from the intake or the exhaust manifold into the combustion chamber without the use of additional passages
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B1/00—Engines characterised by fuel-air mixture compression
    • F02B1/12—Engines characterised by fuel-air mixture compression with compression ignition
    • 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
    • F02D13/0203—Variable control of intake and exhaust valves
    • F02D13/0215—Variable control of intake and exhaust valves changing the valve timing only
    • F02D13/0219—Variable control of intake and exhaust valves changing the valve timing only by shifting the phase, i.e. the opening periods of the valves are constant
    • 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]
    • F02D41/006—Controlling exhaust gas recirculation [EGR] using internal EGR
    • 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

Landscapes

  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Output Control And Ontrol Of Special Type Engine (AREA)

Abstract

An internal combustion engine is disclosed that is operable under low and part load conditions in a controlled auto-ignition mode. The engine has means for independently varying the phase of the exhaust and intake valve events in relation to the crankshaft. When the engine is operating in the controlled auto-ignition mode, the means for adjusting the phase of the exhaust event act to close the exhaust valve at a variable instant (34 - 34') during the engine exhaust stroke so as to trap a variable proportion of the residual gases of one cycle in the cylinder. This varies the engine load by determining the quantity of fresh charge that may be admitted into the cylinder in a subsequent cycle. In the present invention, the means for adjusting the phase of the intake event (36' - 36'') act to allow a variable proportion of the charge in the cylinder to be expelled into the intake port at the commencement or termination of the intake event. This causes a variable amount of the cylinder charge to mix with the fresh air charge in the intake port and thereby controls the auto-ignition combustion properties of the trapped charge, allowing in particular the peak combustion pressure to be reduced.

Description

ENGINE WITH CONTROLLED AUTO-IGNITION Field of the invention The present invention relates to an internal combustion engine operable under low and part load conditions in a controlled auto-ignition mode, the engine having means for independently varying the phase of the exhaust and intake valve events in relation to the crankshaft.
Background of the invention It is known to use valve timing to control engine load and to create the conditions necessary under low and part load operating conditions to cause controlled auto-ignition.
As is known, controlled auto-ignition is advantageous under certain conditions as it yields very low NOx emission, and permits complete combustion even with very low mixture strengths. Auto-ignition is also characterised by very rapid burn causing rapid pressure increases and high pressure peaks. It is because of these high pressure peaks that autoignition needs to be avoided at all cost when operating with high loads (it is the cause of engine knocking) but even with moderate loads steps may be required to limit the rate of burn during auto-ignition.
When valve timing is used to control the load in autoignition mode, the exhaust event is chosen to have a shorter duration than the exhaust stroke and the valve lift may also be reduced as compared with full load operation. By adjusting the phase of the exhaust event to close the exhaust valve at a variable instant before TDC during the engine exhaust stroke, a variable high proportion of the residual gases of one cycle is trapped in the cylinder to trigger auto-ignition in the next engine operating cycle.
The proportion of trapped residual gases also determines the engine load by limiting the quantity of fresh charge that
may be admitted into the cylinder in a subsequent cycle.
The timing of the intake event does not directly affect the mass of the intake charge and it has little or no effect on engine load.
Object of the invention The present invention recognises that the timing of the intake event does affect the engine in other ways and seeks to optimise the setting of the intake valve timing when the engine is operating in controlled auto-ignition mode.
Summary of the invention According to the present invention, the means for adjusting the phase of the intake event are operative to allow a variable proportion of the charge in the cylinder to be expelled into the intake port at the commencement or termination of the intake event so as to cause a variable amount of the charge to mix with the fresh air charge in the intake port and thereby control the auto-ignition combustion properties of the trapped charge.
The invention is predicated upon the discovery that within a large window the intake valve timing can be altered at will without affecting the engine performance. However, when the timing is advanced or retarded from a mean position, the peak pressure occurring during auto-ignition is reduced. In both cases, the reason is believed to be the effect that the intake valve timing has on the mixing of the fresh charge with residual gases within the intake port.
If the intake valve opens early, the cylinder pressure is greater than ambient pressure and some of the residual gas could expand into the intake port to mix there with the fresh charge in the same engine operating cycle. Conversely, if the intake valve is allowed to remain open after BDC,
some of the charge is expelled by the piston into the intake port where it will mix with the fresh charge for the next operating cycle.
The mixing of the fresh charge with residual gases before it is admitted into the combustion chamber reduces the rate of auto-ignition and thus provides a degree of control over the peak combustion pressure.
Though the optimum timing of the intake event can be chosen during engine calibration to achieve the desired maximum peak pressures in the combustion chamber, it is also possible to provide peak pressure sensors and to vary the intake event timing in response to a threshold pressure being exceeded so as to increase the dilution of the fresh charge with residual gases in the intake port.
The intake valve timing may be controlled either by phase shifting cams of fixed profile in relation to the crankshaft phase or by the use of independent camless actuators, such as electro-magnetic electro-hydraulic and piezoelectric actuators.
Brief description of the drawings The invention will now be described further, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a block diagram of an engine having a variable valve timing control system for operating the engine in a controlled auto-ignition mode, and Figure 2 is a phase diagram showing the timing of the intake and exhaust events both during full load operation and during operation in the controlled auto-ignition mode.
Detailed description of the preferred embodiments Figure 1 shows an engine 10 fitted with a variable valve timing system (not shown). Variable valve timing systems of various types are known in the prior art and the invention is not restricted to any particularly kind of system. For the purposes of example only, it is assumed that the engine is fitted with two cams for each valve, one having a fixed profile corresponding to the event 30 or 32 in Figure 2 and the other having a fixed profile corresponding to the valve events 34 or 36 in Figure 2. One cam at a time is selected by the use of a switchable tappet depending on the operating mode of the engine.
When the engine is operating under high load and idling conditions, which require conventional ignition, the cams with full lift and maximum duration events 30 and 32 are selected and these events can be further controlled by phase shifting if desired though such control is not of particular relevance to the present invention. The invention is instead concerned with operation in the controlled auto-ignition mode under low and part load conditions, using the second set of cams having lower lift and shorter event duration 34 and 36.
During controlled auto-ignition operation, the engine load is controlled by varying the timing of the exhaust event. In the position shown by the solid line 34, the exhaust valve closes early in the exhaust stroke and traps a high proportion of the residual gases in the combustion chamber. By contrast, in the position represented by the dotted line 34', the exhaust valve closes later in the exhaust stroke to trap enough residual gases to trigger auto-ignition but the mass of the residual gases is reduced resulting in an increase in the fresh charge that may be admitted in the subsequent intake stroke, resulting in a corresponding increase in engine load and power output.
During controlled auto-ignition, the intake throttle is left wide open and only the exhaust valve timing is used to regulate the engine load. Because of the open throttle, adjustment of the intake valve timing event from its means position represented by the solid line 36 to either of its limit positions represented by the dotted lines 36'and 36" has no appreciable effect on engine performance. It has been found however that the intake valve timing does reduce peak combustion pressure if advanced or retarded significantly from its mean setting represented by the solid line 36.
The reason for the drop in peak pressure is believed to be that the burn rate of the charge is moderated by mixing residual gases with the fresh charge in the intake port. In the case of the timing being advanced to the position represented by the dotted line 36', the intake valve opens while the pressure in the combustion chamber is above ambient pressure so that some residual gases expand into the intake port when the intake valve first opens and are later readmitted into the combustion chamber in the same engine operating cycle. In the case of the intake valve timing being retarded to the position represented by the dotted line 36''on the other hand, the intake valve remains open after BDC so that some residual gases are pushed out by the piston into the intake port where they mix with the fresh charge to be admitted into the combustion chamber in the next engine cycle.
It is possible to set the intake valve by calibration so that the peak pressure during controlled auto-ignition always remains within acceptable limits. Alternatively, sensors 14 may detect peak pressure and when a maximum threshold is exceeded the control system 12 may act to vary the intake valve timing in such as a manner as to reduce the peak pressure.

Claims (5)

  1. CLAIMS 1. An internal combustion engine operable under low and part load conditions in a controlled auto-ignition mode, the engine having means for independently varying the phase of the exhaust and intake valve events in relation to the crankshaft, wherein, when the engine is operating in the controlled auto-ignition mode, the means for adjusting the phase of the exhaust event are operative to close the exhaust valve at a variable instant during the engine exhaust stroke so as to trap a variable proportion of the residual gases of one cycle in the cylinder and thereby vary the engine load by determining the quantity of fresh charge that may be admitted into the cylinder in a subsequent cycle, characterised in that the means for adjusting the phase of the intake event are operative to allow a variable proportion of the charge in the cylinder to be expelled into the intake port at the commencement or termination of the intake event so as to cause a variable amount of the charge to mix with the fresh air charge in the intake port and thereby control the auto-ignition combustion properties of the trapped charge.
  2. 2. An internal combustion engine as claimed in claim 1, wherein a sensors is provided to measure peak combustion pressure and the intake event timing is varied in response to a threshold pressure being exceeded so as to increase the dilution of the fresh charge with residual gases in the intake port.
  3. 3. An internal combustion engine as claimed in claim 1 or claim 2, wherein the engine intake valve is operated by a cam of fixed profile and the valve timing is effected by altering the phase of the cam in relation to the phase of the engine crankshaft.
  4. 4. An internal combustion engine as claimed in claim 1 or claim 2, wherein the engine intake valve is operated by an independent camless actuator.
  5. 5. An internal combustion engine substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.
GB0104336A 2001-02-22 2001-02-22 Engine with controlled auto-ignition Withdrawn GB2372537A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB0104336A GB2372537A (en) 2001-02-22 2001-02-22 Engine with controlled auto-ignition

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GB0104336A GB2372537A (en) 2001-02-22 2001-02-22 Engine with controlled auto-ignition

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GB0104336D0 GB0104336D0 (en) 2001-04-11
GB2372537A true GB2372537A (en) 2002-08-28

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1519016A1 (en) * 2003-09-24 2005-03-30 Isuzu Motors Limited Internal combustion engine of premixed charge compression self-ignition type

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2134596A (en) * 1983-02-04 1984-08-15 Fev Forsch Energietech Verbr Fresh charge intake quantity control in an internal combustion engine
US5367990A (en) * 1993-12-27 1994-11-29 Ford Motor Company Part load gas exchange strategy for an engine with variable lift camless valvetrain
JPH10252512A (en) * 1997-03-13 1998-09-22 Toyota Motor Corp Compressed ignition internal combustion engine
WO2000028197A1 (en) * 1998-10-26 2000-05-18 Ab Volvo Method of controlling the process of combustion in an internal combustion engine, and engine with means for controlling the engine valves
US6082342A (en) * 1997-03-07 2000-07-04 Institut Francais Du Petrole Process for controlling self-ignition in a 4-stroke engine
GB2349419A (en) * 1999-04-30 2000-11-01 Ford Global Tech Inc An internal combustion engine with internal egr to thermally condition fuel
EP1085191A2 (en) * 1999-09-17 2001-03-21 Nissan Motor Co., Ltd. Compression self-ignition gasoline internal combustion engine

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2134596A (en) * 1983-02-04 1984-08-15 Fev Forsch Energietech Verbr Fresh charge intake quantity control in an internal combustion engine
US5367990A (en) * 1993-12-27 1994-11-29 Ford Motor Company Part load gas exchange strategy for an engine with variable lift camless valvetrain
US6082342A (en) * 1997-03-07 2000-07-04 Institut Francais Du Petrole Process for controlling self-ignition in a 4-stroke engine
JPH10252512A (en) * 1997-03-13 1998-09-22 Toyota Motor Corp Compressed ignition internal combustion engine
WO2000028197A1 (en) * 1998-10-26 2000-05-18 Ab Volvo Method of controlling the process of combustion in an internal combustion engine, and engine with means for controlling the engine valves
GB2349419A (en) * 1999-04-30 2000-11-01 Ford Global Tech Inc An internal combustion engine with internal egr to thermally condition fuel
EP1085191A2 (en) * 1999-09-17 2001-03-21 Nissan Motor Co., Ltd. Compression self-ignition gasoline internal combustion engine

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1519016A1 (en) * 2003-09-24 2005-03-30 Isuzu Motors Limited Internal combustion engine of premixed charge compression self-ignition type
US6925984B2 (en) 2003-09-24 2005-08-09 Isuzu Motors Limited Internal combustion engine of premixed charge compression self-ignition type

Also Published As

Publication number Publication date
GB0104336D0 (en) 2001-04-11

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