GB2396885A - Turbocharged diesel engine with means for rapidly reducing EGR flow - Google Patents

Turbocharged diesel engine with means for rapidly reducing EGR flow Download PDF

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Publication number
GB2396885A
GB2396885A GB0300059A GB0300059A GB2396885A GB 2396885 A GB2396885 A GB 2396885A GB 0300059 A GB0300059 A GB 0300059A GB 0300059 A GB0300059 A GB 0300059A GB 2396885 A GB2396885 A GB 2396885A
Authority
GB
United Kingdom
Prior art keywords
valve
egr
actuator
diesel engine
turbocharged diesel
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Withdrawn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
GB0300059A
Other versions
GB0300059D0 (en
Inventor
Timothy Mark Lancefield
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.)
Mechadyne PLC
Original Assignee
Mechadyne PLC
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 Mechadyne PLC filed Critical Mechadyne PLC
Priority to GB0300059A priority Critical patent/GB2396885A/en
Publication of GB0300059D0 publication Critical patent/GB0300059D0/en
Priority to EP03104550A priority patent/EP1435451A3/en
Publication of GB2396885A publication Critical patent/GB2396885A/en
Withdrawn legal-status Critical Current

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Classifications

    • 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
    • F02M26/52—Systems for actuating EGR valves
    • F02M26/55—Systems for actuating EGR valves using vacuum actuators
    • 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
    • F02M26/65—Constructional details of EGR valves
    • F02M26/66—Lift valves, e.g. poppet valves
    • F02M26/67—Pintles; Spindles; Springs; Bearings; Sealings; Connections to actuators
    • 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
    • F02M26/65—Constructional details of EGR valves
    • F02M26/70—Flap valves; Rotary valves; Sliding valves; Resilient valves
    • 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
    • F02M26/02—EGR systems specially adapted for supercharged engines
    • F02M26/04—EGR systems specially adapted for supercharged engines with a single turbocharger
    • 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
    • F02M26/13—Arrangement or layout of EGR passages, e.g. in relation to specific engine parts or for incorporation of accessories
    • F02M26/40—Arrangement or layout of EGR passages, e.g. in relation to specific engine parts or for incorporation of accessories with timing means in the recirculation passage, e.g. cyclically operating valves or regenerators; with arrangements involving pressure pulsations
    • 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
    • F02M26/52—Systems for actuating EGR valves
    • F02M26/53—Systems for actuating EGR valves using electric actuators, e.g. solenoids
    • F02M26/54—Rotary actuators, e.g. step motors

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Exhaust-Gas Circulating Devices (AREA)

Abstract

The engine has an EGR valve 12,14 with an actuator 16, eg vacuum operated, to enable the valve opening to be varied continuously and means separate from the actuator 16 for reducing the EGR flow significantly faster than can be achieved by that actuator 16 alone. The means for rapidly reducing the EGR flow may be a second actuator 18, fig. 1, eg having a larger diaphragm and a stronger spring, acting on the closure element 12 of the EGR valve. Alternatively, fig.2, the means for rapidly reducing the EGR flow may be a second valve 20 in series with the EGR valve 12,14 and operated by its own actuator 22. The EGR valve may have a hollow rotary closure member (12', fig.3) into which a second closure member (24) may be inserted rapidly by a linear actuator (26) regardless of the angular position of the closure member (12'). In a modification, fig.4, a valve (32) is provided for bypassing the vacuum modulator (30) of the EGR valve to cause it to close rapidly. The rapid reduction of EGR flow enables the mass flow through the compressor and turbine to be increased to improve eg transient torque rise rate.

Description

TURBOCHARGED DIESEL ENGINE
The present invention relates to a turbocharged Diesel engine and in particular to improving the transient torque rise rate in a turbocharged Diesel engine operating with high levels of exhaust gas re-circulation (EGR).
It is known that modern light-duty diesel engines use high levels of exhaust gas re-circulation. A major consequence of this is that the mass flow rates through the compressor and turbine of the turbocharger are significantly reduced as compared with an engine operating without high levels of EGR. Conventionally, the amount of EGR is managed by controlling the orifice size of an EGR valve and the pressure differential across the EGR valve.
In current, state of the art, diesel engines use variable geometry turbines "VGT" to manage the pressure differential across the EGR valve. Opening the VGT nozzles reduces boost, much as a waste-gate would, but it also reduces the exhaust back pressure on the engine. Conversely closing the turbine nozzles can be used to increase the pressure difference across the engine to increase EGR, a function that would previously have been carried out by an intake throttle.
Modern EGR valves are continuously variable and position controlled, rather than on/off valves, and as a consequence the EGR valve and the VGT interact to provide the required amount of EGR. Because of this, they need relatively sophisticated controllers and control strategies.
The relative priorities and speeds of response of the EGR valve and VGT nozzle controllers are a major constraint on calibration of light duty diesel engines as there is a trade-off between fuel economy and transient drivability through the interaction of the VGT and EGR valve orifice - 2 settings. Fuelling systems can respond on a stroke by stroke basis and will, within measurement system accuracy, follow a prescribed air-fuel ratio trajectory very closely.
Therefore, the limitations on transient operation are imposed by the air/EGR management.
When using AFR fuelling control, as is now common, transient torque rise is a function of how quickly the air flow can be increased. There is initially a problem of lo rapidly reducing the amount of EGR to increase air flow and then of achieving a target boost level, through management of the turbine and, if present, variable valve actuation (VVA), as quickly as possible to maximise volumetric efficiency throughout the transient.
The present invention is only concerned with reducing the EGR flow as quickly as possible to enable the mass flow through the compressor and turbine to be increased.
According to the present invention, there is provided a turbocharged diesel engine including an EGR valve having a first actuator to enable the valve opening to be varied continuously and means separate from said first actuator for reducing the EGR flow significantly faster than can be achieved by said actuator alone.
In a first embodiment of the invention, the means for reducing the EGR flow comprises a second actuator acting upon the closure element of the EGR valve and operative to force the closure element into a fully closed position regardless of the position of the first actuator.
In a second embodiment of the invention, the means for reducing the EGR flow rapidly comprises a second valve, acting in series with the EGR valve and operated by a second valve actuator to shut off the EGR flow independently of the - 3 - position of the first actuator and of the opening of the EGR valve.
The EGR valve may conveniently be a poppet valve connected in series with a butterfly valve acting as a shut- off valve. Alternatively, the two valves may be coincident instead of being connected one downstream of the other. For example, the continuously variable EGR may be a rotary valve having a hollow closure member formed with a metering lo opening whereas the second valve may be a linear valve having a closure member that is slidable axially relative to the hollow closure member of the rotary valve to cover the metering opening of the rotary valve.
In a further embodiment of the invention, the actuator of the EGR valve is vacuum or pressure controlled and the means for rapidly reducing the EGR flow comprises a valve for cutting off the vacuum or pressure supply to the actuator.
In all embodiments of the invention, the means for reducing the EGR flow must be capable of operating rapidly in the closing direction.
The invention will now be described further, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a schematic sectional view of a first embodiment of the present invention, Figure 2 is a similar view to Figure 1 showing a second embodiment of the invention, Figure 3 is also a similar view to Figure 1 showing a third embodiment of the invention, and Figure 4 is a detail of a fourth embodiment of the invention. - 4 -
In Figure 1, there is shown an EGR duct 10 which is connected at one end to the intake system of an engine and at its other end to the engine exhaust system. The flow of EGR gases along the duct 10 is controlled by an EGR valve which comprises a closure member 12 moved towards and away from a valve seat 14 defined within the EGR duct 10 by means of a vacuum operated actuator 16.
The actuator is generally conventional and need not lo therefore be described in detail. The illustrated actuator 16 comprises a diaphragm biased by a spring in a direction to close the EGR valve. By applying a vacuum to the working chamber above the diaphragm, the closure member 12 is raised off its seat 14 to open the EGR valve. The valve opening defined between the closure member 12 and the seat 14 is continuously variable by appropriately modulating the applied vacuum.
The actuator 16 is not in itself capable of closing the EGR valve rapidly and for this purpose the embodiment shown in Figure 1 is provided with a second actuator 18. The actuator 18 has a larger diaphragm and a stronger spring than the first actuator 16. The spring is normally held compressed by a vacuum so that the actuator 18 is normally ineffective. When the EGR flow is to be cut off rapidly, the working chamber of the actuator 18 is connected to atmosphere whereupon the strong spring within the actuator 18 extends its output rod and moves the whole of the first actuator 16 in a direction to close the EGR valve. Because of the strength of the spring in the second actuator the EGR valve will be closed quickly regardless of the position of the diaphragm of the actuator 16.
In the embodiment of Figure 2, the EGR valve is the same as has been described with reference to Figure 1 and it will not be described a second time. In this embodiment, a butterfly 20 arranged in series with the EGR valve and operated by its own actuator 22 is provided to achieve a rapid shut off of the EGR flow. The butterfly 20 is normally held in a fully open position and the EGR flow is regulated by the EGR valve in the normal manner. To shut the EGR flow off rapidly, the actuator 22 is connected to atmosphere and its spring acts on the butterfly to move is rapidly to its closed position.
The embodiment of Figure 3 operates on the same lo principle as that of Figure 2 in that two separate valves are provided. In this embodiment, the EGR valve is a rotary valve having a closure member 12' mounted in an EGR duct 10' and rotated by a rotary actuator 16'. The closure member 12', which is also shown separately in perspective in the drawing, has an opening which is covered to a greater or lesser extent as the closure member 12' is rotated to regulate the flow of EGR gases along the duct 10'. To shut the EGR flow off rapidly, a linear actuator 26 acts on a second closure member 24 which is movable into the hollow closure member 12' of the rotary valve to cover the valve opening completely regardless of the angular position of the closure member 12'.
The position of the closure members 12 and 12' in the previously described embodiments is determined by the level of vacuum applied to their actuators and this is typically set by a vacuum modulator having a slow response time making it unsuitable for closing the EGR valve rapidly.
In the embodiment of Figure 4, a valve 32 is provided for bypassing the vacuum modulator 30 that sets the level of the vacuum applied to the actuator of the EGR valve, for example the actuator 16 in Figures 1 and 2. The illustrated valve 32 has a spool 34 movable by a suitable electrical or vacuum actuator between two positions. The valve 32 has four ports namely, a port 36 connected to a vacuum source, a port vented to atmosphere, a port 38 for supplying a vacuum to - 6 - the vacuum modulator 30 and a port 42 connected to the line joining the vacuum modulator to the EGR valve actuator.
In the normal position illustrated, the valve 32 connects the ports 36 and 38 to one another so that the vacuum source is connected to the vacuum modulator 30. When the EGR flow is to be shut off rapidly, the spool 34 is moved to its other end position, where the ports 36 and 38 are isolated from one another and the ports 40 and 42 are lo connected to one another. The vacuum supply to the vacuum modulator 30 is therefore shut off and the EGR actuator is connected to atmosphere so that the EGR is closed by the spring of the actuator.
It will be noted that in all the described embodiments, the opening of the EGR valve need only occur at its normal rate as determined by the speed at which the actuator 16 or 16' can move the closure member 12 or 12' of the EGR valve.

Claims (7)

1. A turbocharged diesel engine including an EGR valve having a first actuator to enable the valve opening to be varied continuously and means separate from said first actuator for reducing the EGR flow significantly faster than can be achieved by said actuator alone.
2. A turbocharged diesel engine as claimed in claim lo 1, wherein the means for reducing the EGR flow comprises a second actuator acting upon the closure element of the EGR valve and operative to force the closure element into a fully closed position regardless of the position of the first actuator.
3. A turbocharged diesel engine as claimed in claim 1, wherein the means for reducing the EGR flow rapidly comprises a second valve, acting in series with the EGR valve and operated by a second valve actuator to shut off the EGR flow independently of the position of the first actuator and of the opening of the EGR valve.
4. A turbocharged diesel engine as claimed in claim 3, wherein the EGR valve is a poppet valve connected in series with a butterfly valve acting as a rapid shut-off valve.
5. A turbocharged diesel engine as claimed in claim 3, wherein the two valves are coincident, the continuously variable EGR being a rotary valve having a hollow closure member formed with a metering opening and the second valve being a linear valve having a closure member that is slidable axially relative to the hollow closure member of the rotary valve to cover the metering opening of the rotary valve. - 8
6. A turbocharged diesel engine as claimed in claim 1, wherein the actuator of the EGR valve is vacuum or pressure controlled and the means for rapidly reducing the EGR flow comprises a valve for cutting off the vacuum or pressure supply to the actuator.
7. A turbocharged diesel engine having an EGR valve substantially as herein described with reference to and as illustrated in the accompanying drawings.
GB0300059A 2003-01-03 2003-01-03 Turbocharged diesel engine with means for rapidly reducing EGR flow Withdrawn GB2396885A (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
GB0300059A GB2396885A (en) 2003-01-03 2003-01-03 Turbocharged diesel engine with means for rapidly reducing EGR flow
EP03104550A EP1435451A3 (en) 2003-01-03 2003-12-04 EGR valve for a turbocharged diesel engine

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB0300059A GB2396885A (en) 2003-01-03 2003-01-03 Turbocharged diesel engine with means for rapidly reducing EGR flow

Publications (2)

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GB0300059D0 GB0300059D0 (en) 2003-02-05
GB2396885A true GB2396885A (en) 2004-07-07

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GB0300059A Withdrawn GB2396885A (en) 2003-01-03 2003-01-03 Turbocharged diesel engine with means for rapidly reducing EGR flow

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EP (1) EP1435451A3 (en)
GB (1) GB2396885A (en)

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2009103021A (en) * 2007-10-23 2009-05-14 Aisan Ind Co Ltd Passage switching valve
DE102008003177A1 (en) * 2008-01-04 2009-07-09 Continental Automotive Gmbh Exhaust gas recirculation valve for a motor vehicle
US9182047B2 (en) 2013-03-13 2015-11-10 Kohler Mira Limited Valve with fail-safe device
GB2511799A (en) * 2013-03-13 2014-09-17 Kohler Mira Ltd Valve

Citations (2)

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Publication number Priority date Publication date Assignee Title
JPH07166969A (en) * 1993-12-14 1995-06-27 Nissan Motor Co Ltd Exhaust-recycling control device for engine
JPH1061503A (en) * 1996-08-26 1998-03-03 Hino Motors Ltd Exhaust gas recirculation device of multi-cylinder engine with supercharger

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5491619A (en) * 1977-12-29 1979-07-20 Toyota Motor Corp Exhaust gas recirculation apparatus
JPS55156244A (en) * 1979-05-21 1980-12-05 Nissan Motor Co Ltd Device for mitigating influence of speed reduction of internal combustion engine
JPS56159555A (en) * 1980-05-12 1981-12-08 Nissan Motor Co Ltd Exhaust gas recirculation control system
US4398524A (en) * 1981-07-24 1983-08-16 Ford Motor Company Exhaust gas recirculation system
EP0512139A1 (en) * 1991-05-07 1992-11-11 Siemens Aktiengesellschaft Actuator driven by an electric motor
JP3412347B2 (en) * 1995-05-22 2003-06-03 三菱電機株式会社 Exhaust gas recirculation control valve
US5606957A (en) * 1995-12-06 1997-03-04 Caterpillar Inc. Control system for exhaust gas recirculation

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH07166969A (en) * 1993-12-14 1995-06-27 Nissan Motor Co Ltd Exhaust-recycling control device for engine
JPH1061503A (en) * 1996-08-26 1998-03-03 Hino Motors Ltd Exhaust gas recirculation device of multi-cylinder engine with supercharger

Also Published As

Publication number Publication date
GB0300059D0 (en) 2003-02-05
EP1435451A2 (en) 2004-07-07
EP1435451A3 (en) 2006-04-19

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