CN113217233A - Engine exhaust gas circulation system and engine misfire judging method - Google Patents
Engine exhaust gas circulation system and engine misfire judging methodDownload PDFInfo
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- CN113217233A CN113217233ACN202110499829.0ACN202110499829ACN113217233ACN 113217233 ACN113217233 ACN 113217233ACN 202110499829 ACN202110499829 ACN 202110499829ACN 113217233 ACN113217233 ACN 113217233A
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- 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
- 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
- F02B77/00—Component parts, details or accessories, not otherwise provided for
- F02B77/08—Safety, indicating, or supervising devices
- F02B77/083—Safety, indicating, or supervising devices relating to maintenance, e.g. diagnostic device
- 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
- F02M26/17—Arrangement or layout of EGR passages, e.g. in relation to specific engine parts or for incorporation of accessories in relation to the intake system
- F02M26/19—Means for improving the mixing of air and recirculated exhaust gases, e.g. venturis or multiple openings to the intake system
- 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
- F02M26/45—Sensors specially adapted for EGR systems
- F02M26/46—Sensors specially adapted for EGR systems for determining the characteristics of gases, e.g. composition
- F02M26/47—Sensors specially adapted for EGR systems for determining the characteristics of gases, e.g. composition the characteristics being temperatures, pressures or flow rates
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- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Fluid Mechanics (AREA)
- Analytical Chemistry (AREA)
- Exhaust-Gas Circulating Devices (AREA)
Abstract
Description
Technical Field
The invention relates to the technical field of engines, in particular to an engine exhaust gas circulation system and an engine misfire judging method.
Background
With the upgrading of emission regulations, the requirement on the limit value of engine emission is lower, and the requirement on the original emission of the engine is lower in order to balance the aftertreatment cost and the engine performance comprehensively despite the exhaust aftertreatment system. EGR (exhaust gas recirculation) systems, are recognized by the industry to reduce engine emissions, particularly NOx(nitrogen oxide) emissions. However, the EGR rate is lower in the prior art, so how to improve the EGR rate is a problem to be solved urgently at present.
Disclosure of Invention
The invention discloses an engine exhaust gas circulating system and an engine fire judging method, which are used for effectively reducing the original emission of an engine.
In order to achieve the purpose, the invention provides the following technical scheme:
in a first aspect, the present invention provides an engine exhaust gas recirculation system comprising: a plurality of cylinders;
a first exhaust manifold and a second exhaust manifold for receiving exhaust from at least two of the plurality of cylinders;
an intake manifold in communication with at least one intake port of the plurality of cylinders;
a mixer comprising a first inlet, a second inlet, and a mixer outlet;
said first and second exhaust manifolds connected to said intake manifold by a mixer for supplying exhaust gas from said first and second exhaust manifolds to said intake manifold;
wherein the first exhaust manifold comprises a first outlet and a second outlet connected to the mixer first inlet; the second exhaust manifold includes a third outlet and a fourth outlet connected to the mixer second inlet; the mixer outlet is selectively in communication with the intake manifold or intercooler;
the mixer includes: the air inlet section comprises a first air distribution path and a second air distribution path, and the pipe diameter of at least one air distribution path in the pipe diameter of the first air distribution path and the pipe diameter of the second air distribution path along the exhaust flowing direction is gradually reduced; the pipe diameter of the mixing section is gradually increased along the exhaust flowing direction;
a pressure sensor disposed at an outlet of the mixer.
A first exhaust manifold and a second exhaust manifold for receiving exhaust gases from at least two of the plurality of cylinders, the first exhaust manifold and the second exhaust manifold mixing the two exhaust gas streams into one exhaust gas stream via a mixer, a pressure sensor being provided after an outlet of the mixer to measure a pressure of the mixed exhaust gas stream in real time, the first exhaust manifold and the second exhaust manifold being connected to an intake manifold line via the mixer for supplying exhaust gases from the first exhaust manifold and the second exhaust manifold to the intake manifold; in a particular configuration of the mixer, wherein the first exhaust manifold comprises a first outlet and a second outlet connected to the first inlet of the mixer; the second exhaust manifold comprises a third outlet and a fourth outlet connected with the second inlet of the mixer; the mixer outlet is selectively connectable to an intake manifold or to a intercooler, the first outlet of the first exhaust manifold is connected to the boost system, and the third outlet of the second exhaust manifold is also connected to the boost system. Wherein, the blender includes: the air inlet section comprises a first air distributing channel and a second air distributing channel, and the pipe diameter of at least one air distributing channel in the pipe diameter of the first air distributing channel and the pipe diameter of the second air distributing channel gradually decreases along the exhaust flowing direction; so that the first gas distributing channel and the second gas distributing channel can act as a spray pipe, two exhaust flows with larger difference of thermodynamic states are sprayed, thermodynamic energy converts the two exhaust flows into kinetic energy, the thermodynamic states are closer when the two exhaust flows enter the mixing section and are mixed, and the kinetic energy follows the law of conservation of mechanical energy in the mixing section, so that the two exhaust flows are mixed in the mode, entropy is increased, and the two exhaust flows are mixed,
The loss is small, and the mixing efficiency is high; in the mixing section, the pipe diameter of the mixing section is gradually increased along the exhaust flowing direction; so that the pipe section of the mixing section functions as a diffuser pipe, so that the static pressure of the mixed exhaust flow is increased and the flow speed is reduced after the mixed exhaust flow passes through the mixing section, and the resistance loss in the subsequent flow is reducedThe losses are smaller. When exhaust flows of different states are mixed by a mixer, the entropy increase is smaller,
The loss is lower, and the gas mixing efficiency is improved, so that the EGR rate is improved; moreover, the exhaust flow mixing under different states is carried out through the special pulse mixer, more pulse characteristics of the mixed exhaust flow are kept, the pressure of the exhaust flow in the EGR is measured in real time through the addition of the pressure sensor, and the misfire diagnosis is carried out through algorithm design.
Optionally, an end of the first branch gas channel facing away from the mixing section forms the first inlet; one end of the second gas distribution path, which is far away from the mixing section, forms the second inlet; an end of the mixing section facing away from the air intake section forms the mixer outlet.
Optionally, the first gas distribution path comprises a first circulation area and a second circulation area which are communicated along the gas exhaust direction;
the pipe diameters of the first circulation areas are the same along the exhaust direction, and the pipe diameters of the second circulation areas are gradually reduced along the exhaust direction.
Optionally, the second gas distribution path comprises a third flow-through area and a fourth flow-through area which are communicated along the exhaust direction;
the pipe diameters of the third circulation areas are the same along the exhaust direction, and the pipe diameter of the fourth circulation area gradually decreases along the exhaust direction.
Optionally, the mixing section comprises a fifth flow-through zone, a sixth flow-through zone and a seventh flow-through zone arranged in sequence along the exhaust direction;
the fifth circulation area is communicated with the second circulation area and the fourth circulation area, the pipe diameter of the fifth circulation area is the same along the exhaust direction, the pipe diameter of the sixth circulation area is gradually increased along the exhaust direction, and the pipe diameter of the seventh circulation area is the same along the exhaust direction.
Optionally, a first cooler is provided in the conduit between the second outlet of the first exhaust manifold and the first inlet of the mixer;
a second cooler is disposed in the conduit between the fourth outlet of the second exhaust manifold and the second inlet of the mixer.
Optionally, a third cooler is provided at the mixer outlet.
In a second aspect, the present invention provides a method for determining engine misfire, applied to the engine exhaust gas recirculation system of any one of the first aspect;
collecting the pressure value after passing through the exhaust mixer in real time through a pressure sensor;
determining a current exhaust pulse characteristic value corresponding to each cylinder in the plurality of cylinders according to the pressure value;
and judging whether the exhaust pulse ratio corresponding to the cylinder is smaller than a preset value or not, and judging that the cylinder catches fire when the exhaust pulse ratio corresponding to the cylinder is smaller than the preset value.
Optionally, the pressure value is acquired in real time by a pressure sensor with a crank angle as a scale.
Optionally, the exhaust pulse characteristic value of each cylinder is scaled by a crank angle, and the exhaust pressure is integrated, wherein the integration interval is from the exhaust start of the cylinder to the exhaust start of the next cylinder.
Drawings
FIG. 1 is a pressure pulse diagram of a first exhaust manifold and a second exhaust manifold of the prior art;
FIG. 2 is a schematic diagram of an engine exhaust gas recirculation system according to an embodiment of the present disclosure;
fig. 3 is a schematic diagram of an internal structure of a mixer according to an embodiment of the present invention;
FIG. 4 is a graph comparing EGR rates with and without a mixer, provided by an embodiment of the present invention;
FIG. 5 is a graph of pressure pulses measured by the pressure sensor in the absence of a misfire in the cylinder provided in accordance with an embodiment of the present invention;
FIG. 6 is a graph of pressure pulses measured by the pressure sensor in the event of a cylinder misfire as provided by an embodiment of the present invention;
FIG. 7 is a schematic diagram of an exhaust pulse feature value extraction according to an embodiment of the present invention;
fig. 8 is a schematic diagram illustrating the engine misfire determination method according to the embodiment of the present invention.
Icon: 1-a supercharging system; 100-cylinder body; 200-a first exhaust manifold; 210-a first outlet; 220-a second outlet; 300-a second exhaust manifold; 310-a third outlet; 320-a fourth outlet; 400-a mixer; 410-a first gas distribution path; 411-first flow-through zone; 412-a second flow-through zone; 420-a second gas distributing channel; 421-third flow-through zone; 422-a fourth flow-through zone; 430-a mixing section; 431-a fifth flow-through zone; 432-a sixth flow-through zone; 500-a pressure sensor; 600-an EGR valve; 700-an intake manifold; 800-intercooler; 900-a first cooler; 1000-second cooler.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
When an exhaust valve of a cylinder of the engine is opened, high-temperature and high-pressure gas in the cylinder immediately enters an exhaust manifold, the initial pressure is very high, and the pressure is gradually reduced along with the progress of an exhaust process to form a complete exhaust pulse. To utilize this exhaust pulse energy, a pulse exhaust system is commonly used, taking a six-cylinder engine as an example, with the first to third cylinders sharing afirst exhaust manifold 200 and the fourth to sixth cylinders sharing asecond exhaust manifold 300. Significant exhaust pulsing was observed on either thefirst exhaust manifold 200 or thesecond exhaust manifold 300, as shown in fig. 1.
As can be seen from fig. 1, the thermodynamic state of both exhaust streams is at most times very different. In the prior art, the two air streams are typically mixed directly and then introduced intointake manifold 700, or each is mixed after passing through a single valve and then introduced intointake manifold 700. For a system directly mixing these two gas flows, the mixing process of the gases is typical as can be seen from the second law of thermodynamicsThe larger the difference of thermodynamic states of the exhaust streams before mixing is, the larger the irreversible degree is, namely the larger the entropy increase is,
the larger the (available energy) loss is, the more the EGR rate is, the higher the EGR rate is, only the exhaust back pressure can be increased if the EGR rate is increased, and the increase of the exhaust back pressure can increase the pumping work, so that the fuel consumption is deteriorated; for the systems which respectively pass through the single valve and then are mixed, due to the high temperature and pulse characteristics of the air flow, the high-frequency switching of the one-way valve can be caused, so that although the EGR rate is improved, the one-way valve is easy to damage, and the serious reliability problem is caused.
In order to solve the problems in the prior art, themixer 400 is added to the engine exhaust gas circulation system provided in the embodiment of the present invention to reduce the mixing of the two air flows
Therefore, the EGR rate is improved, and the influence on the pumping work is small.
As shown in fig. 2 to 4, an embodiment of the present invention provides an engine exhaust gas circulation system including: acylinder block 100, wherein thecylinder block 100 includes a plurality of cylinders;
afirst exhaust manifold 200 and asecond exhaust manifold 300 for receiving exhaust gases from at least two of the plurality of cylinders;
anintake manifold 700 in communication with at least one intake port of the plurality of cylinders;
amixer 400, themixer 400 including a first inlet, a second inlet, and amixer 400 outlet;
wherein thefirst exhaust manifold 200 includes afirst outlet 210 and asecond outlet 220 connected to a first inlet of themixer 400; thesecond exhaust manifold 300 includes athird outlet 310 and afourth outlet 320 connected to the second inlet of themixer 400; themixer 400 outlet may optionally be in communication with theintake manifold 700 orintercooler 800;
themixer 400 includes: the air inlet section comprises a firstair distributing path 410 and a secondair distributing path 420, and the pipe diameter of at least one air distributing path in the pipe diameter of the firstair distributing path 410 and the pipe diameter of the secondair distributing path 420 along the exhaust flowing direction is gradually reduced; the pipe diameter of themixing section 430 gradually becomes larger in the exhaust gas flow direction;
apressure sensor 500 disposed at the outlet of themixer 400.
It should be noted that, the exhaust gas flow from the first exhaust manifold 200 and the second exhaust manifold 300 for receiving the exhaust gas from at least two cylinders of the plurality of cylinders, the two exhaust gas flows from the first exhaust manifold 200 and the second exhaust manifold 300 are mixed into one exhaust gas flow by the mixer 400, the pressure sensor 500 is arranged behind the outlet of the mixer 400 to measure the pressure of the mixed exhaust gas flow in real time, and the first exhaust manifold 200 and the second exhaust manifold 300 are connected with the intake manifold 700 by the mixer 400 for supplying the exhaust gas from the first exhaust manifold 200 and the second exhaust manifold 300 to the intake manifold 700; in the specific structure of the mixer 400, among others, the first exhaust manifold 200 includes a first outlet 210 and a second outlet 220 connected to a first inlet of the mixer 400; the second exhaust manifold 300 includes a third outlet 310 and a fourth outlet 320 connected to the second inlet of the mixer 400; the outlet of the mixer 400 is selectively in communication with the intake manifold 700 or the intercooler 800, the first outlet 210 of the first exhaust manifold 200 is connected to the supercharging system 1, and the third outlet 310 of the second exhaust manifold 300 is also connected to the supercharging system 1. Wherein themixer 400 includes: the air inlet section comprises a firstair distributing path 410 and a secondair distributing path 420, and the pipe diameter of at least one air distributing path in the pipe diameter of the firstair distributing path 410 and the pipe diameter of the secondair distributing path 420 along the exhaust flowing direction is gradually reduced; such that the firstbranch gas path 410 and the secondbranch gas path 420 function as a nozzle, such that the two exhaust streams with large difference in thermodynamic state are injected, the thermodynamic energy converts them into kinetic energy, and the thermodynamic state is closer when they are mixed after entering themixing section 430, and the kinetic energy follows the conservation of mechanical energy in the mixing section 430Law, so this way mixes, entropy increases little,
The loss is small, and the mixing efficiency is high; and in themixing section 430, the pipe diameter of themixing section 430 becomes gradually larger in the exhaust gas flow direction; such that the section of themixing section 430 acts as a diffuser, such that the mixed exhaust stream, after passing through themixing section 430, has an increased static pressure, a reduced flow rate, and a lower drag loss in the subsequent flow. When exhaust flows of different states are mixed by themixer 400, the entropy increase is smaller,
The loss is lower, and the gas mixing efficiency is improved, so that the EGR rate is improved; moreover, the exhaust gas flows in different states are mixed through thespecial pulse mixer 400, more pulse characteristics of the mixed exhaust gas flows are reserved, the pressure of the exhaust gas flows in the EGR is measured in real time through the addition of thepressure sensor 500, and misfire diagnosis is performed through algorithm design.
Specifically, anEGR valve 600 is provided at a rear portion of thepressure sensor 500 connected at an outlet of themixer 400 in an exhaust direction, and the outlet of themixer 400 is selectively communicated with theintake manifold 700 or theintercooler 800 through theEGR valve 600.
Specifically, the end of the firstbranch gas path 410 facing away from themixing section 430 forms a first inlet; the end of the secondbranch gas circuit 420 departing from themixing section 430 forms a second inlet; the end of themixing section 430 facing away from the air intake section forms the outlet of themixer 400.
Optionally, the firstgas distribution path 410 includes a first flow-througharea 411 and a second flow-througharea 412 that communicate in the exhaust direction;
the pipe diameters of the first flow-throughareas 411 are the same in the exhaust direction, and the pipe diameters of the second flow-throughareas 412 are gradually smaller in the exhaust direction. I.e., d1 is greater thand 2.
Thesecond flow area 412 acts as a nozzle as the pipe diameter of thesecond flow area 412 decreases in the direction of the exhaust gas, so that the exhaust gas flow with a large difference in thermodynamic state is injected and the thermodynamic energy converts it into kinetic energy.
Optionally, secondgas diversion circuit 420 includes a third flow-throughzone 421 and a fourth flow-throughzone 422 in communication in the exhaust direction;
the pipe diameters of thethird flow area 421 are the same in the exhaust direction, and the pipe diameter of thefourth flow area 422 is gradually reduced in the exhaust direction.
Thesecond flow area 412 functions as a nozzle as the diameter of the pipe of thefourth flow area 422 decreases in the direction of the exhaust gas, so that the exhaust gas flow with a large difference in thermodynamic state is injected and thermodynamic energy converts it into kinetic energy.
Optionally, themixing section 430 comprises a fifth flow-throughzone 431, a sixth flow-throughzone 432 and a seventh flow-through zone arranged in sequence along the exhaust direction;
thefifth circulation area 431 is communicated with thesecond circulation area 412 and thefourth circulation area 422, the pipe diameter of thefifth circulation area 431 is the same along the exhaust direction, the pipe diameter of thesixth circulation area 432 is gradually increased along the exhaust direction, and the pipe diameter of the seventh circulation area is the same along the exhaust direction. I.e., d3 is less thand 4.
Specifically, thesixth flow area 432 in themixing section 430 functions as a diffuser, such that the mixed exhaust flow, after passing through themixing section 430, has an increased static pressure, a decreased flow rate, and a lower drag loss in the subsequent flow. When exhaust flows of different states are mixed by themixer 400, the entropy increase is smaller,
The loss is lower, and the gas mixing efficiency is improved, so that the EGR rate is improved.
Since themixer 400 is based on reducing the entropy increase when two air streams are mixed, there are several ways in which the arrangement of the cooler can be:
in the first mode, afirst cooler 900 is provided in a pipe between thesecond outlet 220 of thefirst exhaust manifold 200 and the first inlet of themixer 400; asecond cooler 1000 is provided in a pipe between thefourth outlet 320 of thesecond exhaust manifold 300 and the second inlet of themixer 400.
In the second mode, a third cooler is provided at the outlet of themixer 400.
Whether the engine adopts themixer 400 or not is subjected to simulation analysis, and the result is shown in fig. 4, so that the EGR rate is greatly improved after the technical scheme is adopted.
The two exhaust streams fromfirst exhaust manifold 200 andsecond exhaust manifold 300 are mixed bymixer 400 and still retain good pulse characteristics. At thepressure sensor 500, a pressure pulse waveform as shown in fig. 5 can be measured when the engine is normally operated, and if a misfire occurs in one of the cylinders in the engine, a pressure pulse waveform as shown in fig. 6 can be measured at the sensor. By contrast, it is apparent that when a misfire occurs in a cylinder, the discharge pressure pulse of the corresponding cylinder is very weak, and is significantly different from that of the non-misfired cylinder.
Therefore, whether an engine cylinder is in fire or not is judged by the following method, and in a second aspect, the invention provides a method for judging the engine fire, which is applied to the engine exhaust gas circulating system in any one of the first aspect;
the pressure value after passing through theexhaust mixer 400 is collected in real time by thepressure sensor 500;
determining an exhaust pulse characteristic value corresponding to each of the plurality of cylinders according to the pressure value;
and judging whether the exhaust pulse ratio corresponding to the cylinder is smaller than a preset value or not, and judging that the cylinder catches fire when the exhaust pulse ratio corresponding to the cylinder is smaller than the preset value.
Specifically, the exhaust pulse ratio is determined by:
selecting the ratio of the current exhaust pulse characteristic value of the cylinder to the historical exhaust pulse characteristic value of the selected cylinder under the working condition;
and the ratio of the current exhaust pulse characteristic value of the selected cylinder to the average value of the historical exhaust pulse characteristic values of other cylinders except the selected cylinder under the working condition.
Thepressure sensor 500 is used for collecting pressure change behind themixer 400 in real time by taking a crank angle as a scale, then extracting exhaust pulse characteristic values corresponding to all cylinders, judging whether the exhaust pulse characteristic values corresponding to the cylinders are smaller than a preset value or not, and judging that the cylinders fire when the exhaust pulse characteristic values corresponding to the cylinders are smaller than the preset value.
Alternatively, the pressure value is collected in real time by thepressure sensor 500 with the crank angle as a scale.
Specifically, the exhaust pulse characteristic value of each cylinder is divided by the crank angle, and the exhaust pressure is integrated, wherein the integration interval is from the exhaust start of the cylinder to the exhaust start of the next cylinder.
The method for extracting the exhaust pulse characteristic value of each cylinder comprises the steps of integrating the exhaust pressure of the interval from the opening of the exhaust valve of the cylinder to the opening of the exhaust valve of the next cylinder, taking a crank angle as a scale, and taking an integrated value as the exhaust pulse characteristic value of the cylinder. Taking a six-cylinder machine as an example (assuming that the firing sequence is one cylinder-five cylinders-three cylinders-six cylinders-two cylinders-four cylinders), the exhaust pulse characteristic value of each cylinder is as shown in fig. 7, i.e. the area under the curve in the figure is the corresponding pulse characteristic value.
The ECU (Electronic Control Unit) extracts the exhaust pulse characteristic value for each cylinder, and then performs misfire determination and history characteristic value storage, and the specific determination method is shown in fig. 8.
S801: acquiring an exhaust pulse characteristic value of a selected cylinder;
s802: determining whether misfires occur in cylinders other than the selected cylinder; if misfiring occurs in the other cylinders, S803 is executed; otherwise, executing S806;
s803: acquiring a current exhaust pulse characteristic value of the selected cylinder, and extracting a historical exhaust pulse characteristic value of the selected cylinder under the working condition;
s804: judging whether the ratio of the current exhaust pulse characteristic value of the selected cylinder to the historical exhaust pulse characteristic value of the selected cylinder under the working condition is smaller than a preset value or not; if the ratio of the current exhaust pulse characteristic value of the selected cylinder to the historical exhaust pulse characteristic value of the selected cylinder under the working condition is smaller than the preset value, S807 is executed; otherwise, executing S805;
s805: storing the current exhaust pulse characteristic value as the historical pulse characteristic value of the selected cylinder under the working condition;
s806: judging whether the ratio of the current exhaust pulse characteristic value of the selected cylinder to the mean value of the historical exhaust pulse characteristic values of other cylinders except the selected cylinder under the working condition is smaller than a preset value or not; if the ratio of the current exhaust pulse characteristic value of the selected cylinder to the mean value of the historical exhaust pulse characteristic values of other cylinders except the selected cylinder under the working condition is smaller than the preset value, executing S807; otherwise, S805 is performed.
For example, the working condition of the diesel engine can be determined by the rotating speed and the fuel injection quantity; for gas engines, the operating conditions can be determined by the rotational speed and the intake pressure, while the preset values for misfire detection can be determined by experimental calibration.
It will be apparent to those skilled in the art that various changes and modifications may be made in the embodiments of the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.
Claims (10)
1. An engine exhaust gas recirculation system, comprising: a plurality of cylinders;
a first exhaust manifold and a second exhaust manifold for receiving exhaust from at least two of the plurality of cylinders;
an intake manifold in communication with at least one intake port of the plurality of cylinders;
a mixer comprising a first inlet, a second inlet, and a mixer outlet;
said first and second exhaust manifolds connected to said intake manifold by a mixer for supplying exhaust gas from said first and second exhaust manifolds to said intake manifold;
wherein the first exhaust manifold comprises a first outlet and a second outlet connected to the mixer first inlet; the second exhaust manifold includes a third outlet and a fourth outlet connected to the mixer second inlet; the mixer outlet is selectively in communication with the intake manifold or intercooler;
the mixer includes: the air inlet section comprises a first air distribution path and a second air distribution path, and the pipe diameter of at least one air distribution path in the pipe diameter of the first air distribution path and the pipe diameter of the second air distribution path along the exhaust flowing direction is gradually reduced; the pipe diameter of the mixing section is gradually increased along the exhaust flowing direction;
a pressure sensor disposed at an outlet of the mixer.
2. The engine exhaust gas circulation system of claim 1, wherein an end of the first gas bypass path facing away from the mixing section forms the first inlet; one end of the second gas distribution path, which is far away from the mixing section, forms the second inlet; an end of the mixing section facing away from the air intake section forms the mixer outlet.
3. The engine exhaust gas circulation system according to claim 2, wherein the first branch gas passage includes a first flow-through region and a second flow-through region that communicate in an exhaust direction;
the pipe diameters of the first circulation areas are the same along the exhaust direction, and the pipe diameters of the second circulation areas are gradually reduced along the exhaust direction.
4. The engine exhaust gas circulation system according to claim 3, wherein the second branch gas passage includes a third flow-through region and a fourth flow-through region that communicate in the exhaust direction;
the pipe diameters of the third circulation areas are the same along the exhaust direction, and the pipe diameter of the fourth circulation area gradually decreases along the exhaust direction.
5. The engine exhaust gas circulation system according to claim 4, wherein the mixing section includes a fifth flow-through zone, a sixth flow-through zone, and a seventh flow-through zone arranged in this order in the exhaust direction;
the fifth circulation area is communicated with the second circulation area and the fourth circulation area, the pipe diameter of the fifth circulation area is the same along the exhaust direction, the pipe diameter of the sixth circulation area is gradually increased along the exhaust direction, and the pipe diameter of the seventh circulation area is the same along the exhaust direction.
6. The engine exhaust gas circulation system according to claim 5, wherein a first cooler is provided on a conduit between the second outlet of the first exhaust manifold and the first inlet of the mixer;
a second cooler is disposed in the conduit between the fourth outlet of the second exhaust manifold and the second inlet of the mixer.
7. An engine exhaust gas recirculation system according to claim 5, characterized in that a third cooler is provided at the mixer outlet.
8. A method of determining engine misfire, characterized by applying the engine exhaust gas circulation system according to any one of claims 1 to 7;
collecting the pressure value after passing through the exhaust mixer in real time through a pressure sensor;
determining an exhaust pulse characteristic value corresponding to each of the plurality of cylinders according to the pressure value;
and judging whether the exhaust pulse ratio corresponding to the cylinder is smaller than a preset value or not, and judging that the cylinder catches fire when the exhaust pulse ratio corresponding to the cylinder is smaller than the preset value.
9. The engine misfire identification method as recited in claim 8, wherein the pressure value is collected in real time by a pressure sensor with a crank angle as a scale.
10. The engine misfire identification method as recited in claim 9, wherein the exhaust pulse characteristic value for each cylinder is scaled by a crank angle and the exhaust pressure is integrated over an interval from the start of the exhaust for the cylinder to the start of the exhaust for the next cylinder.
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| CN115045758A (en)* | 2022-06-17 | 2022-09-13 | 广西玉柴机器股份有限公司 | Monitoring system and monitoring method |
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| CN113217233B (en) | 2022-04-26 |
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