CN111102068B - Engine lean combustion device, control method, engine and automobile - Google Patents
Engine lean combustion device, control method, engine and automobile Download PDFInfo
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- CN111102068B CN111102068B CN201811267607.0A CN201811267607A CN111102068B CN 111102068 B CN111102068 B CN 111102068B CN 201811267607 A CN201811267607 A CN 201811267607A CN 111102068 B CN111102068 B CN 111102068B
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- 238000002485 combustion reaction Methods 0.000 title claims abstract description 72
- 238000000034 method Methods 0.000 title claims abstract description 15
- 239000003054 catalyst Substances 0.000 claims abstract description 14
- 238000004519 manufacturing process Methods 0.000 claims abstract description 5
- 239000007789 gas Substances 0.000 claims description 105
- 239000000446 fuel Substances 0.000 claims description 37
- 238000002347 injection Methods 0.000 claims description 27
- 239000007924 injection Substances 0.000 claims description 27
- 239000001257 hydrogen Substances 0.000 claims description 25
- 229910052739 hydrogen Inorganic materials 0.000 claims description 25
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims description 24
- 239000000126 substance Substances 0.000 claims description 16
- 239000002912 waste gas Substances 0.000 claims description 16
- 239000000203 mixture Substances 0.000 claims description 14
- 238000005192 partition Methods 0.000 claims description 11
- 238000007906 compression Methods 0.000 claims description 7
- 230000007246 mechanism Effects 0.000 claims description 7
- 238000000926 separation method Methods 0.000 claims description 5
- 230000003197 catalytic effect Effects 0.000 claims description 4
- 230000006835 compression Effects 0.000 claims description 4
- 238000010992 reflux Methods 0.000 claims description 4
- 239000000463 material Substances 0.000 claims description 3
- 230000008569 process Effects 0.000 claims description 3
- 230000003647 oxidation Effects 0.000 abstract description 3
- 238000007254 oxidation reaction Methods 0.000 abstract description 3
- 238000005516 engineering process Methods 0.000 description 11
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 6
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 6
- 230000001276 controlling effect Effects 0.000 description 5
- 238000006243 chemical reaction Methods 0.000 description 4
- ORQBXQOJMQIAOY-UHFFFAOYSA-N nobelium Chemical compound [No] ORQBXQOJMQIAOY-UHFFFAOYSA-N 0.000 description 4
- 238000012546 transfer Methods 0.000 description 4
- 238000009413 insulation Methods 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 2
- 230000007797 corrosion Effects 0.000 description 2
- 238000005260 corrosion Methods 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 230000002349 favourable effect Effects 0.000 description 2
- 230000035515 penetration Effects 0.000 description 2
- 239000000047 product Substances 0.000 description 2
- 230000001105 regulatory effect Effects 0.000 description 2
- 239000007921 spray Substances 0.000 description 2
- 230000009471 action Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000006555 catalytic reaction Methods 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 239000000567 combustion gas Substances 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 150000002431 hydrogen Chemical class 0.000 description 1
- 230000002401 inhibitory effect Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000002407 reforming Methods 0.000 description 1
- 238000005096 rolling process Methods 0.000 description 1
- 238000013517 stratification Methods 0.000 description 1
- 239000013589 supplement Substances 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 230000001052 transient effect Effects 0.000 description 1
Classifications
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- 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
- F02B47/00—Methods of operating engines involving adding non-fuel substances or anti-knock agents to combustion air, fuel, or fuel-air mixtures of engines
- F02B47/04—Methods of operating engines involving adding non-fuel substances or anti-knock agents to combustion air, fuel, or fuel-air mixtures of engines the substances being other than water or steam only
- F02B47/08—Methods of operating engines involving adding non-fuel substances or anti-knock agents to combustion air, fuel, or fuel-air mixtures of engines the substances being other than water or steam only the substances including exhaust gas
-
- 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
- F02M25/00—Engine-pertinent apparatus for adding non-fuel substances or small quantities of secondary fuel to combustion-air, main fuel or fuel-air mixture
- F02M25/10—Engine-pertinent apparatus for adding non-fuel substances or small quantities of secondary fuel to combustion-air, main fuel or fuel-air mixture adding acetylene, non-waterborne hydrogen, non-airborne oxygen, or ozone
- F02M25/12—Engine-pertinent apparatus for adding non-fuel substances or small quantities of secondary fuel to combustion-air, main fuel or fuel-air mixture adding acetylene, non-waterborne hydrogen, non-airborne oxygen, or ozone the apparatus having means for generating such gases
-
- 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
-
- 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
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)
- Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)
Abstract
The application belongs to the technical field of engines, and relates to an engine lean combustion device, a control method, an engine and an automobile. According to the lean combustion device of the engine, the oxidation catalyst can be used for replacing the three-way catalyst in the post-treatment, and an additional lean-burn exhaust gas post-treatment device is not required to be added, so that the structural complexity and the manufacturing cost of the engine are reduced.
Description
Technical Field
The invention belongs to the technical field of engines, and particularly relates to an engine lean-burn device, a control method, an engine and an automobile.
Background
Lean burn and EGR (exhaust gas recirculation) technologies have become a new trend in the current engine technology development due to their advantages of high thermal efficiency and low fuel consumption, low NOx emissions, etc.
The existing lean combustion is a technology for realizing stratified combustion by sucking excessive air and forming rich and surrounding lean fuel layers near a spark plug by adopting multiple fuel injections, and the lean combustion technology can greatly improve the thermal efficiency on the premise of ensuring stable combustion. However, the total excess air coefficient in the cylinder is larger than 1, so that the traditional three-way catalyst cannot be used for catalytic conversion of exhaust, complex post-treatment equipment is required to be added, the structural complexity and cost of the engine are increased, and the difficulty of exhaust treatment is increased.
The existing low-pressure EGR is a technology for mixing and pressurizing the exhaust gas with fresh air before the exhaust gas is cooled and introduced into a compressor, and injecting the exhaust gas into a cylinder to perform mixed combustion with fuel. The low-pressure EGR is characterized in that the position for introducing the EGR is in front of the compressor, cooled EGR waste gas has a corrosion effect on the compressor, and higher requirements are put on the materials and corrosion resistance of the compressor.
The existing high-pressure EGR is a technology of injecting exhaust gas into a cylinder together with fresh air after passing the exhaust gas into a compressor to perform mixed combustion with fuel. The high-pressure EGR is introduced into the compressor, so that the defect of low-pressure EGR can be avoided, but the operation condition is greatly narrowed, and the wide popularization is not facilitated.
Disclosure of Invention
The technical problems to be solved by the invention are as follows: aiming at the problems that the existing lean combustion technology of the engine cannot use the traditional three-way catalyst to carry out catalytic conversion on exhaust, complex post-treatment equipment is required to be added, and the structural complexity and cost of the engine are increased, the lean combustion device of the engine, the control method, the engine and the automobile are provided.
In order to solve the technical problems, in one aspect, an embodiment of the present invention provides an engine lean combustion device, which includes a cylinder liner, a piston, an intake channel, an intake valve, an exhaust channel, an exhaust valve, an injector, a direct injection gasoline injector, a spark plug, an exhaust gas recirculation mechanism and an electronic control unit;
A combustion chamber is formed in the cylinder sleeve, an air inlet is formed at the position where the air inlet channel is connected with the combustion chamber, the air inlet can be opened or closed, an air outlet is formed at the position where the air outlet channel is connected with the combustion chamber, the air outlet can be opened or closed, and the electronic control unit is used for controlling the opening time and the opening duration of the air outlet;
The direct injection gasoline injector is used for injecting fuel into the cylinder, and the injected fuel is ignited by the spark plug after being mixed with air flowing through the air inlet channel;
The exhaust gas recirculation mechanism comprises a separation element and a unidirectional flow element, the separation element separates the exhaust passage into a first flow passage and a second flow passage, the unidirectional flow element is arranged on the first flow passage, and the injector is used for injecting substances capable of catalyzing and generating hydrogen into the second flow passage;
In the exhaust stroke of the engine, the electronic control unit controls the exhaust valve to keep the whole stroke open, the unidirectional flow element allows the exhaust gas discharged by the combustion chamber to pass through, and the exhaust gas discharged by the combustion chamber flows to the exhaust gas discharge device through the first flow passage and the second flow passage;
In the air inlet stroke of the engine, the electronic control unit controls the exhaust valve to be kept open in a preset time period so as to enable the exhaust gas with the required flow to flow back to the combustion chamber; during the process of the exhaust gas flowing back to the combustion chamber, the one-way flow element blocks the exhaust gas flowing back to the combustion chamber, and the exhaust gas flowing back to the combustion chamber flows into the combustion chamber through the second flow passage.
Optionally, the injector is mounted on a cylinder head of the engine and extends into the second flow passage.
Optionally, the separation element is a partition plate, and the partition plate is consistent with the trend of the exhaust passage;
the one-way flow element is a one-way valve which allows only exhaust gases in the first flow passage to flow from the combustion chamber to the exhaust gas discharge device.
Optionally, an air guide surface is arranged at the top of the piston.
Optionally, a surface of the exhaust valve facing away from the piston is coated with a catalyst that facilitates the catalytic production of hydrogen from the substance injected by the injector.
According to the lean combustion device of the engine, in the air inlet stroke of the engine, the electronic control unit controls the exhaust valve to be kept open in a preset time period, so that the exhaust gas with the required flow flows back to the combustion chamber. The unidirectional flow element blocks the exhaust gas flowing back to the combustion chamber from flowing into the combustion chamber through the second flow passage during the backflow of the exhaust gas to the combustion chamber. Therefore, in the air intake stroke of the engine, the opening time and the opening duration of the exhaust valve are controlled by the electronic control unit, and the reflux quantity of the exhaust gas introduced into the cylinder from the second flow passage of the exhaust passage can be freely regulated so as to be matched with different engine working conditions. The substance capable of catalyzing and generating hydrogen is injected into the second flow passage through the injector, and the returned exhaust gas in the second flow passage is mixed with the hydrogen generated by the substance to generate reformed exhaust gas and flows into the cylinder. The hydrogen in the reformed exhaust gas helps to accelerate the rate of the combustion reaction and the recirculated exhaust gas in the reformed exhaust gas helps to reduce the maximum temperature of the combustion process to reduce NOx emissions. In this way, the content of the easily oxidized products such as HC and CO in the exhaust gas is higher, NOx is greatly reduced, the oxidation catalyst can be directly adopted for the aftertreatment to replace the three-way catalyst, and an additional lean-burn exhaust gas aftertreatment device is not required to be added, so that the structural complexity and the manufacturing cost of the engine are reduced.
In another aspect, an embodiment of the present invention provides an engine including the engine lean burn device described above.
In yet another aspect, an embodiment of the present invention provides an automobile including the engine lean burn device described above.
In still another aspect, an embodiment of the present invention provides a control method of the lean-burn engine device described above, including:
mixing fresh air introduced into the cylinder from the air inlet passage with fuel injected into the cylinder by the direct injection gasoline injector to form a combustible mixture;
In the air intake stroke of the engine, the electric control unit controls the exhaust valve to be opened in a preset time period so as to enable the waste gas with the required flow to flow back to the combustion chamber;
injecting a substance capable of catalyzing and generating hydrogen into the second flow passage through the injector, so that the backflow waste gas in the second flow passage is mixed with the hydrogen generated by the substance to generate reformed waste gas;
Fresh air introduced into the cylinder through the air inlet channel is wrapped and clamped with reformed waste gas flowing back into the cylinder, so that in-cylinder hot EGR layering of internal combustible mixed gas and external reformed waste gas is realized;
The piston moves to the upper dead center, and the spark plug is controlled to spark to ignite the combustible mixture in the cylinder.
Optionally, controlling, by the electronic control unit, the exhaust valve to open for a preset period of time during an intake stroke of the engine includes:
When the engine is in a small-load working condition and the intake stroke of the engine is in the small-load working condition, the electric control unit controls the exhaust valve to be kept open in a time period corresponding to the later period of the intake stroke;
When the engine is in the air intake stroke and the engine is in the heavy load working condition, the electric control unit controls the exhaust valve to be opened in a time period corresponding to the early stage of the air intake stroke.
Optionally, the direct injection gasoline injector injecting fuel into the cylinder includes:
in the air intake stroke of the engine, the direct injection gasoline injector injects 1 or 2 times of fuel into the cylinder according to the current running condition of the engine;
In the middle section of the compression stroke of the engine, the direct injection gasoline injector injects 1 time of fuel into the cylinder.
Drawings
FIG. 1 is a schematic illustration of an engine lean burn device according to an embodiment of the present invention;
FIG. 2 is a flow chart of a method of controlling an engine lean burn device according to an embodiment of the present invention.
Reference numerals in the specification are as follows:
1. Cylinder sleeve; 2. a piston; 201. an air guide surface; 3. a spark plug; 4. an air inlet channel; 5. an intake valve; 6. an exhaust passage; 601. a first flow passage; 602. a second flow passage; 7. an exhaust valve; 8. a direct injection gasoline injector; 9. an ejector; 10. an exhaust gas recirculation mechanism; 101. a partition member; 102. a unidirectional flow element.
Detailed Description
In order to make the technical problems, technical schemes and beneficial effects solved by the invention more clear, the invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.
As shown in fig. 1, the lean-burn engine device provided by the embodiment of the invention comprises a cylinder sleeve 1, a piston 2, a spark plug 3, an air inlet channel 4, an air inlet valve 5, an air outlet channel 6, an air outlet valve 7, a direct injection gasoline injector 8, an injector 9, an exhaust gas recirculation mechanism 10 and an electric control unit.
The piston 2 can reciprocate in the cylinder liner 1, and a combustion chamber is formed in the cylinder liner 1. The exhaust passage 6 forms an exhaust port at a position where it meets the combustion chamber. The exhaust valve 7 may open or close the exhaust port. The electronic control unit is used for controlling the opening time and the opening duration of the exhaust valve 7.
The position of the air inlet channel 4 connected with the combustion chamber forms an air inlet. The intake valve 5 may open or close the intake port. The air inlet 4 is a high-tumble air inlet.
The direct injection gasoline injector 8 is used for injecting fuel into a cylinder, and the injected fuel is ignited by the spark plug 3 after being mixed with air flowing through the air inlet passage 4.
The exhaust gas recirculation mechanism 10 includes a partition member 101 and a one-way flow member 102. The partition member 101 partitions the exhaust passage into a first flow passage 601 and a second flow passage 602, and the unidirectional flow element 102 is disposed on the first flow passage 601.
The injector 9 is mounted on a cylinder cover of the engine and extends into the second flow passage 602, and the injector 9 is used for injecting substances capable of generating hydrogen in a catalysis way into the second flow passage 602. Such materials may be, for example, water or alcohol fuels.
During the exhaust stroke of the engine, the electronic control unit controls the exhaust valve 7 to keep open for the whole stroke, the unidirectional flow element 102 allows the exhaust gas discharged from the combustion chamber to pass through, and the exhaust gas discharged from the combustion chamber passes through the first flow passage 601 and the second flow passage 602 to the exhaust gas discharge device.
In the intake stroke of the engine, the electronic control unit controls the exhaust valve 7 to be kept open for a preset period of time so as to enable the exhaust gas with the required flow to flow back to the combustion chamber; during the backflow of the exhaust gas into the combustion chamber, the unidirectional flow element 102 blocks the exhaust gas flowing back into the combustion chamber (the backflow exhaust gas cannot pass through the first flow passage 601), and the exhaust gas flowing back into the combustion chamber flows into the combustion chamber through the second flow passage 602.
According to the lean combustion device of the engine, in the air intake stroke of the engine, the opening time and the opening duration of the exhaust valve 7 are controlled by the electronic control unit, so that the reflux amount of the exhaust gas introduced into the cylinder through the second flow passage 602 of the exhaust passage 6 can be freely regulated to match different engine working conditions. The substance capable of catalyzing the generation of hydrogen is injected into the second flow path 602 by the injector 9, and the recirculated exhaust gas in the second flow path 602 is mixed with the hydrogen generated from the substance to generate reformed exhaust gas and flows into the cylinder. When the engine is in a small load working condition, the electronic control unit controls the exhaust valve 7 to be kept open in a time period corresponding to the later period of the air intake stroke so as to control the reformed exhaust gas to move to the surface of the piston 2 just at the ignition moment to form a heat insulation layer, and heat transfer of combustion gas to the engine body is reduced. When the engine is in a large-load working condition, the electronic control unit controls the exhaust valve 7 to be opened in a period corresponding to the early stage of the intake stroke. The hydrogen in the reformed exhaust gas helps to accelerate the rate of the combustion reaction and the recirculated exhaust gas in the reformed exhaust gas helps to reduce the maximum temperature of the combustion process to reduce NOx emissions. In this way, the content of the easily oxidized products such as HC and CO in the exhaust gas is higher, NOx is greatly reduced, the oxidation catalyst can be directly adopted for the aftertreatment to replace the three-way catalyst, and an additional lean-burn exhaust gas aftertreatment device is not required to be added, so that the structural complexity and the manufacturing cost of the engine are reduced.
In addition, the embodiment of the invention adopts the recirculated reformed exhaust gas, which not only has the advantages of inhibiting knocking, reducing NOx emission, reducing heat transfer loss and the like of the EGR technology, but also makes up the defects of the EGR technology. The special requirements of low-pressure EGR on the compressor are not existed, and the test working condition is not limited like the high-pressure EGR. The opening time and the opening duration of the exhaust valve 7 are controlled by the electronic control unit to control the amount and the position of the reformed exhaust gas entering the cylinder so as to match different engine working conditions, and the method can be theoretically suitable for the full MAP operation of the engine.
In addition, compared with the hysteresis brought by the closed-loop adjustment of the EGR technology, the embodiment of the invention can immediately adjust the flow of the reflux waste gas according to the change of the working condition in the next cycle, and has more advantages in the aspects of transient working condition performance and emission.
In addition, the back flow waste gas is innovatively combined with the waste gas reforming technology, and the water or alcohol fuel is catalyzed and decomposed by the catalyst coated on the surface of the exhaust valve to obtain hydrogen, so that the initial combustion rate in the cylinder is accelerated, the highest temperature in the combustion process is reduced by the waste gas, and the highest temperature in the combustion process is reduced to reduce NOx emission, and the water or alcohol fuel and the catalyst supplement each other.
In one embodiment, as shown in FIG. 1, the dividing element 101 is a partition that is oriented in line with the exhaust passage 6. More preferably, the partition extends along a center line of the exhaust passage 6, the unidirectional flow element 102 is a unidirectional valve, the partition divides the exhaust passage 6 into the first flow passage 601 and the second flow passage 602, and the unidirectional valve is fixedly disposed on an inner wall of the first flow passage 601. The check valve allows only the exhaust gas in the first flow passage 60 to flow from the combustion chamber to the exhaust gas discharge device. The arrangement of the check valve enables the exhaust gas to be smoothly discharged through the first flow channel 601 and the second flow channel 602 in the exhaust stroke, but the exhaust gas in the first flow channel 601 is blocked by the check valve in the backflow process, and the backflow exhaust gas can only flow into the cylinder through the second flow channel 602, so that the layering of the exhaust gas in the cylinder is primarily realized.
In one embodiment, as shown in fig. 1, the top of the piston 2 is provided with an air guiding surface 201. The piston 2 with the air guide surface 201 is used for guiding the working medium in the cylinder to keep a stronger rolling flow state in the compression process, so that the hot EGR layering in the cylinder is realized.
In the exhaust gas recirculation stage, the injector 9 injects a substance (such as water or alcohol fuel) that can catalyze and generate hydrogen into the second flow passage 602, and the substance is decomposed into a gas containing hydrogen under the action of a catalyst smeared on the back surface of the exhaust valve 7, and the gas containing hydrogen is mixed with the recirculated exhaust gas to form reformed exhaust gas into a cylinder, and the reformed exhaust gas is initially stratified.
Fresh air enters the cylinder through the high-tumble air inlet channel 4, and the reformed exhaust gas which is wrapped and refluxed is kept in a stronger tumble state in the compression process under the guidance of the piston 2 with the air guide surface 201, so that in-cylinder hot EGR layering (exhaust gas layering) of the internal combustible mixed gas (mixture of fresh air and fuel) and the external reformed exhaust gas is realized.
In the intake stroke of the engine, in-cylinder direct injection is main injection, aiming at injecting the fuel quantity required by output power torque, wherein the direct injection gasoline injector 8 injects 1 or 2 times of fuel into the cylinder according to different operation conditions of the engine. In the middle of the compression stroke of the engine, the direct injection gasoline injector 8 injects 1 time of fuel (small amount of fuel) into the cylinder. Due to the gradual increase of the in-cylinder pressure, the spray penetration distance is shortened, and more oil gas is concentrated in the area near the spark plug 3, so that the subsequent formation and combustion stability of the fire nuclei are facilitated.
When the piston 2 runs near the top dead center, the ignition plug 3 jumps, and the combustible mixture starts to burn.
When the engine is in a small load working condition, the electric control unit controls the exhaust valve 7 to be kept open in a time period corresponding to the later period of the air intake stroke, and controls the reformed waste gas to be gathered on the surface of the piston 2 at the ignition moment to form a heat insulation layer so as to reduce the heat transfer of the combustion mixed gas to the engine body and improve the heat efficiency.
When the engine is in a large-load working condition, the electric control unit controls the exhaust valve 7 to be kept open in a time period corresponding to the early stage of the air inlet stroke, the reformed exhaust gas is controlled to be gathered near the spark plug 3 at the ignition moment, the hydrogen in the reformed exhaust gas is helpful for accelerating the chemical reaction of the mixed gas, and the exhaust gas part in the reformed exhaust gas is helpful for reducing the highest temperature of the combustion process so as to reduce the NOx emission.
In addition, the embodiment of the invention also provides an engine, which comprises the engine lean combustion device of the embodiment.
In addition, the embodiment of the invention also provides an automobile, which comprises the engine lean combustion device of the embodiment.
In addition, as shown in fig. 2, the embodiment of the invention further provides a lean combustion control method of an engine, which comprises the following steps:
a. Fresh air introduced into the cylinder from the intake passage 4 is mixed with fuel injected into the cylinder by the direct injection gasoline injector 8 to form a combustible mixture.
The direct injection gasoline injector injects fuel into the cylinder in two stages: in the first stage, in the intake stroke of the engine, the direct injection gasoline injector 8 injects 1 or 2 times of fuel into the cylinder according to different operation conditions of the engine, and in this stage, the direct injection in the cylinder is main injection, so as to inject the fuel quantity required by the output power torque. In the second stage, the direct injection gasoline injector 8 injects 1 time of fuel (small amount of fuel) into the cylinder in the middle of the compression stroke of the engine. As the pressure in the cylinder is gradually increased, the spray penetration distance is shortened, more oil gas is concentrated in the area near the spark plug 3, and the oil injection in the second stage is favorable for forming a thicker combustible mixture near the spark plug 3 and is favorable for the subsequent formation and combustion stability of a flame kernel.
B. In the intake stroke of the engine, the exhaust valve 7 is controlled to be opened in a preset time period by the electronic control unit so as to enable the exhaust gas with the required flow to flow back to the combustion chamber.
Preferably, controlling the exhaust valve 7 to open for a preset period of time by the electronic control unit during an intake stroke of the engine includes:
when the engine is in the air intake stroke and the engine is in a small load working condition, the electric control unit controls the exhaust valve 7 to be opened in a period corresponding to the later stage of the air intake stroke. Therefore, the reformed exhaust gas is controlled to be gathered on the surface of the piston 2 at the ignition moment to form a heat insulation layer, so that the heat transfer of the combustion mixture gas to the engine body is reduced, and the heat efficiency is improved.
When the engine is in the air intake stroke and the engine is in the heavy load working condition, the electric control unit controls the exhaust valve to be opened in a time period corresponding to the early stage of the air intake stroke. In this way, the reformed exhaust gas is controlled to accumulate near the ignition plug 3 at the time of ignition, the hydrogen in the reformed exhaust gas contributes to accelerating the chemical reaction of the mixture, and the exhaust gas portion in the reformed exhaust gas contributes to lowering the highest temperature of the combustion process to reduce NOx emissions.
C. The substance capable of catalyzing the generation of hydrogen is injected into the second flow path 602 through the injector 9, and the recirculated exhaust gas in the second flow path 602 is mixed with the hydrogen generated from the substance to generate reformed exhaust gas.
For example, during the exhaust gas recirculation phase, the injector 9 injects water or alcohol fuel into the second flow passage 602, the water or alcohol fuel is decomposed into hydrogen by the catalyst coated on the surface of the exhaust valve 7 facing away from the piston 2, and the hydrogen is mixed with the recirculated exhaust gas to form reformed exhaust gas into the cylinder, and the reformed exhaust gas is stratified primarily.
D. Fresh air introduced into the cylinder through the air inlet passage 4 is wrapped with reformed exhaust gas flowing back into the cylinder, so that in-cylinder hot EGR stratification of the internal combustible mixture and the external reformed exhaust gas is realized.
Specifically, fresh air enters the cylinder through the high-tumble inlet channel 4, and the reformed exhaust gas which is wrapped and reflowed maintains a strong tumble state in the compression process under the guidance of the piston 2 with the air guide surface 201, so that in-cylinder hot EGR layering (exhaust gas layering) of the internal combustible mixture (mixture of fresh air and fuel) and the external reformed exhaust gas is realized.
E. The piston 2 runs to the upper dead center, and the spark plug 3 is controlled to spark to ignite the combustible mixture in the cylinder.
The foregoing description of the preferred embodiments of the invention is not intended to be limiting, but rather is intended to cover all modifications, equivalents, and alternatives falling within the spirit and principles of the invention.
Claims (10)
1. The lean combustion device of the engine is characterized by comprising a cylinder sleeve, a piston, a spark plug, an air inlet channel, an air inlet valve, an exhaust channel, an exhaust valve, an ejector, a direct injection gasoline injector, an exhaust gas reflux mechanism and an electric control unit;
A combustion chamber is formed in the cylinder sleeve, an air inlet is formed at the position where the air inlet channel is connected with the combustion chamber, the air inlet can be opened or closed, an air outlet is formed at the position where the air outlet channel is connected with the combustion chamber, the air outlet can be opened or closed, and the electronic control unit is used for controlling the opening time and the opening duration of the air outlet;
The direct injection gasoline injector is used for injecting fuel into the cylinder, and the injected fuel is ignited by the spark plug after being mixed with air flowing through the air inlet channel;
The exhaust gas recirculation mechanism comprises a separation element and a unidirectional flow element, the separation element separates the exhaust passage into a first flow passage and a second flow passage, the unidirectional flow element is arranged on the first flow passage, and the injector is used for injecting substances capable of catalyzing and generating hydrogen into the second flow passage;
In the exhaust stroke of the engine, the electronic control unit controls the exhaust valve to keep the whole stroke open, the unidirectional flow element allows the exhaust gas discharged by the combustion chamber to pass through, and the exhaust gas discharged by the combustion chamber flows to the exhaust gas discharge device through the first flow passage and the second flow passage;
In the air inlet stroke of the engine, the electronic control unit controls the exhaust valve to be kept open in a preset time period so as to enable the exhaust gas with the required flow to flow back to the combustion chamber; during the process of the exhaust gas flowing back to the combustion chamber, the one-way flow element blocks the exhaust gas flowing back to the combustion chamber, and the exhaust gas flowing back to the combustion chamber flows into the combustion chamber through the second flow passage.
2. The lean-burn engine apparatus of claim 1 wherein said injector is mounted to a cylinder head of the engine and extends into said second flow passage.
3. The lean-burn engine apparatus of claim 1 wherein said partition member is a partition plate that is oriented in line with said exhaust passage;
the one-way flow element is a one-way valve which allows only exhaust gases in the first flow passage to flow from the combustion chamber to the exhaust gas discharge device.
4. The lean-burn engine apparatus of claim 1 wherein the top of the piston is provided with an air-guiding surface.
5. The lean-burn engine apparatus of claim 1 wherein a surface of said exhaust valve facing away from said piston is coated with a catalyst that facilitates the catalytic production of hydrogen from material injected by said injector.
6. A control method of the engine lean-burn apparatus according to any one of claims 1 to 5, characterized by comprising:
mixing fresh air introduced into the cylinder from the air inlet passage with fuel injected into the cylinder by the direct injection gasoline injector to form a combustible mixture;
In the air intake stroke of the engine, the electric control unit controls the exhaust valve to be opened in a preset time period so as to enable the waste gas with the required flow to flow back to the combustion chamber;
injecting a substance capable of catalyzing and generating hydrogen into the second flow passage through the injector, so that the backflow waste gas in the second flow passage is mixed with the hydrogen generated by the substance to generate reformed waste gas;
Fresh air introduced into the cylinder through the air inlet channel is wrapped and clamped with reformed waste gas flowing back into the cylinder, so that in-cylinder hot EGR layering of internal combustible mixed gas and external reformed waste gas is realized;
The piston moves to the upper dead center, and the spark plug is controlled to spark to ignite the combustible mixture in the cylinder.
7. The control method according to claim 6, wherein controlling the exhaust valve to open for a preset period of time by the electronic control unit during an intake stroke of the engine includes:
When the engine is in a small-load working condition and the intake stroke of the engine is in the small-load working condition, the electric control unit controls the exhaust valve to be kept open in a time period corresponding to the later period of the intake stroke;
When the engine is in the air intake stroke and the engine is in the heavy load working condition, the electric control unit controls the exhaust valve to be opened in a time period corresponding to the early stage of the air intake stroke.
8. The control method according to claim 7, characterized in that the direct injection gasoline injector injects fuel into the cylinder includes:
in the air intake stroke of the engine, the direct injection gasoline injector injects 1 or 2 times of fuel into the cylinder according to the current running condition of the engine;
In the middle section of the compression stroke of the engine, the direct injection gasoline injector injects 1 time of fuel into the cylinder.
9. An engine comprising the lean-burn engine apparatus of any one of claims 1-5.
10. An automobile comprising the engine lean burn device of any one of claims 1 to 5.
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| CN113914974B (en) * | 2020-07-08 | 2023-02-03 | 长城汽车股份有限公司 | Method and device for reducing emission of nitrogen oxides and automobile |
| CN114810336A (en) * | 2022-05-05 | 2022-07-29 | 中国第一汽车股份有限公司 | Lean-burn internal combustion engine system and vehicle with same |
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