CN113482762A - Combustion chamber and combustion system of medium-heavy diesel engine - Google Patents
Combustion chamber and combustion system of medium-heavy diesel engine Download PDFInfo
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- CN113482762A CN113482762A CN202110871908.XA CN202110871908A CN113482762A CN 113482762 A CN113482762 A CN 113482762A CN 202110871908 A CN202110871908 A CN 202110871908A CN 113482762 A CN113482762 A CN 113482762A
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- 238000002485 combustion reaction Methods 0.000 title claims abstract description 157
- 238000002347 injection Methods 0.000 claims abstract description 54
- 239000007924 injection Substances 0.000 claims abstract description 54
- 230000007704 transition Effects 0.000 abstract description 3
- 239000003921 oil Substances 0.000 description 33
- 239000004071 soot Substances 0.000 description 22
- 239000000446 fuel Substances 0.000 description 14
- 239000000295 fuel oil Substances 0.000 description 14
- 238000000034 method Methods 0.000 description 12
- 230000008569 process Effects 0.000 description 9
- 239000000203 mixture Substances 0.000 description 8
- 239000010705 motor oil Substances 0.000 description 8
- 238000002156 mixing Methods 0.000 description 6
- 239000012895 dilution Substances 0.000 description 5
- 238000010790 dilution Methods 0.000 description 5
- 230000015572 biosynthetic process Effects 0.000 description 4
- 238000013461 design Methods 0.000 description 4
- 238000010586 diagram Methods 0.000 description 4
- 230000009471 action Effects 0.000 description 3
- 238000011010 flushing procedure Methods 0.000 description 3
- 230000006872 improvement Effects 0.000 description 3
- 238000012545 processing Methods 0.000 description 3
- 239000000243 solution Substances 0.000 description 3
- 230000000903 blocking effect Effects 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 238000009792 diffusion process Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000003344 environmental pollutant Substances 0.000 description 2
- 238000001125 extrusion Methods 0.000 description 2
- 239000010687 lubricating oil Substances 0.000 description 2
- 238000003754 machining Methods 0.000 description 2
- 230000008520 organization Effects 0.000 description 2
- 231100000719 pollutant Toxicity 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 239000007921 spray Substances 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000017525 heat dissipation Effects 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- RJIWZDNTCBHXAL-UHFFFAOYSA-N nitroxoline Chemical compound C1=CN=C2C(O)=CC=C([N+]([O-])=O)C2=C1 RJIWZDNTCBHXAL-UHFFFAOYSA-N 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
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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
- F02B23/00—Other engines characterised by special shape or construction of combustion chambers to improve operation
- F02B23/08—Other engines characterised by special shape or construction of combustion chambers to improve operation with positive ignition
- F02B23/10—Other engines characterised by special shape or construction of combustion chambers to improve operation with positive ignition with separate admission of air and fuel into cylinder
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- 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
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- General Engineering & Computer Science (AREA)
- Combustion Methods Of Internal-Combustion Engines (AREA)
Abstract
The application relates to a combustion chamber and a combustion system of a medium-heavy diesel engine, and relates to the technical field of automobile engines and related systems. This heavy diesel engine's combustion chamber in includes first throat structure and second throat structure, wherein, first throat structure is the annular structure, the axial cross-section of first throat structure is from last to including first step circular arc section, step straightway and second step circular arc section down, first step circular arc section is outside protrusion, second step circular arc section is inboard protrusion towards, step straightway slope sets up in order to connect first step circular arc section and second step circular arc section, the second throat structure is located the below of first throat structure, the second throat structure is the cylinder of vertical setting, and with the bottom of second step circular arc section passes through the circular arc and connects the transition. The combustion chamber that this application provided has solved among the relevant art combustion chamber and has leaded to towards the problem of cylinder liner and incomplete combustion to the injection contained angle adaptability is low.
Description
Technical Field
The application relates to the technical field of automobile engines and related systems, in particular to a combustion chamber and a combustion system of a medium-heavy diesel engine.
Background
At present, diesel engines have the advantages of low oil consumption, high thermal efficiency, low pollutant emission, good economy and the like, so that the diesel engines are more and more accepted and used by the market, and the market is extremely wide in both the automotive field and the non-automotive field. The combustion chamber of the diesel engine is a part where fuel oil and air of the diesel engine are mixed to form combustible mixed gas and are combusted, and has important influence on the power, the economy, the reliability and the pollutant discharge of the diesel engine.
According to the different of the mode that working medium formed and the structural style of combustion chamber, the diesel engine combustion chamber can be divided into two main categories: direct injection combustors and divided combustors. The direct injection type combustion chamber is also called as a direct injection type combustion chamber for short, and can be divided into a semi-open type combustion chamber and an open type combustion chamber according to the depth of a pit at the top of a piston. The separated combustion chamber has the structural characteristics that the separated combustion chamber is provided with an auxiliary combustion chamber in the cylinder cover besides a main combustion chamber at the top of the piston, the auxiliary combustion chamber and the main combustion chamber are connected through a channel, and when the separated combustion chamber works, fuel oil is not directly sprayed into the main combustion chamber but is sprayed into the auxiliary combustion chamber, so that the working medium mixing quality is good, the air utilization rate is high, and a perfect combustion process can be achieved. However, the split combustion chamber is much more complicated in structure than the direct injection combustion chamber, the ratio of the surface area to the volume is also large, and the heat dissipation loss is large due to the influence of the strong air movement during operation, and the flow loss due to the channel throttling effect is also large, so that the split combustion diesel engine is generally less efficient and less economical than the direct injection diesel engine, and has been rarely used at present.
With the increase of fuel injection pressure, the use of a deep pit combustion chamber in the direct injection type combustion chamber is gradually reduced, and a shallow-basin type combustion chamber in the direct injection type combustion chamber is commonly used in the most widely-applied combustion chamber scheme, and the shape of the shallow-basin type combustion chamber is a omega combustion chamber in a straight port/reduced port shape. In the related art, the shallow-basin type combustion chamber is continuously improved, the improvement of the combustion chamber mainly emphasizes the effect of the shape of the combustion chamber on the mixture of the mixture, the conditions of a matched oil injection system and a vortex structure are less mentioned, and when the straight-mouth/reduced-mouth combustion chamber is matched with an improper oil nozzle, the fuel oil and the air are insufficiently mixed, so that the thermal efficiency of an engine is reduced, and the economical efficiency and the dynamic performance are reduced; when the included angle of the oil nozzle is too large relative to the combustion chamber, the phenomenon that fuel impacts a cylinder sleeve can occur, part of fuel on the wall is scraped into an oil pan by an oil ring to dilute engine oil, and the fuel still attached to the cylinder wall can obviously increase the quantity of generated Soot due to incomplete combustion.
Disclosure of Invention
The embodiment of the application provides a combustion chamber and a combustion system of a medium and heavy diesel engine, and aims to solve the problems that in the related art, the combustion chamber has low adaptability to an injection included angle, so that a cylinder liner is flushed and incomplete combustion is caused.
In a first aspect, a combustion chamber of a medium and heavy diesel engine is provided, which comprises:
the first necking structure is an annular structure, the axial section of the first necking structure comprises a first step circular arc section, a step straight line section and a second step circular arc section from top to bottom, the first step circular arc section protrudes towards the outer side, the second step circular arc section protrudes towards the inner side, and the step straight line section is obliquely arranged to connect the first step circular arc section and the second step circular arc section;
and the second necking structure is positioned below the first necking structure, is in a vertically arranged cylindrical shape, and is connected and transited with the bottom of the second step circular arc section through an arc.
In some embodiments, the angle of inclination of the straight section of the step ranges from 10 ° to 30 °.
In some embodiments, the length of the straight section of the step ranges from 1 mm to 3 mm.
In some embodiments, the radius of the first step circular arc section and the radius of the second step circular arc section range from 1 mm to 1.5 mm.
In some embodiments, the height of the second necking structure ranges from 1 mm to 4 mm.
In some embodiments, the combustor further comprises a bottom chamber structure, and the axial cross section of the bottom chamber structure is omega-shaped and is in transition with the bottom of the second necking structure through a circular arc connection. The value range of the ratio of the diameter of the second necking structure to the maximum diameter of the bottom cavity structure is 0.95-0.99.
In some embodiments, the height of the first necking structure ranges from 3mm to 6 mm.
In a second aspect, a combustion system for a medium and heavy duty diesel engine is provided, comprising: the combustion system comprises the combustion chamber.
In some embodiments, the combustion system comprises a plurality of oil injection nozzles, the plurality of oil injection nozzles are arranged above the first necking structure and at least partially extend into the first necking structure, and the included angle between the oil injection nozzles and the central axis of the combustion chamber is 73.5-78.5 degrees.
The beneficial effect that technical scheme that this application provided brought includes:
the embodiment of the application provides a combustion chamber of medium and heavy diesel engine, this combustion chamber sets up axial cross-section from last to including first step circular arc section down, the first throat structure of step straightway and second step circular arc section, and make first step circular arc section outwards bulge, second step circular arc section inwards bulges, and the slope sets up the step straightway and connects first step circular arc section and second step circular arc section through it, then set up the second throat structure in the below of first throat structure, the second throat structure is the cylinder of vertical setting, it passes through the circular arc with the bottom of second step circular arc section and is connected the transition. Firstly, the combustion chamber is provided with the structure, so that the injection included angle of the combustion chamber before the injection included angle is obviously increased, the structure of the combustion chamber can flow and separate during combustion due to the special shape of the first necking structure, a vortex is generated, after the vortex is generated, a vortex can be generated in air flow, an oil beam can be influenced by the air flow at the moment and can be prevented from rushing towards a cylinder sleeve, the phenomenon of rushing towards the cylinder sleeve can be effectively prevented under the condition of large injection included angle, after the injection included angle is increased, the angle of the combustion chamber can be correspondingly increased in a manner of being matched with an oil sprayer, and the influence of errors generated during processing and assembly on the performance of an engine is reduced; secondly, because the combustion chamber is difficult to impact the cylinder sleeve, the problems of engine oil dilution or high combustion soot can be effectively avoided; in addition, the step straight-line segment can guide the air flow developed from the second necking structure, the mixing of air and fuel oil on the upper portion of the piston is promoted, the utilization rate of air in the cylinder is increased, the performance of the engine is improved, and the emission of soot is reduced.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
FIG. 1 is a schematic structural diagram of an axial cross section of a combustion chamber of a medium and heavy duty diesel engine provided by an embodiment of the application;
FIG. 2 is a partial schematic structural view of an axial cross section of a combustion chamber of a medium and heavy duty diesel engine provided by an embodiment of the present application;
FIG. 3 is an equivalence ratio distribution diagram of a combustion chamber of a medium and heavy diesel engine provided by an embodiment of the application, wherein the fuel injection included angle of the combustion chamber is 150 degrees;
FIG. 4 is a graph comparing soot emissions test results for a combustion chamber of a medium and heavy duty diesel engine provided by embodiments of the present application;
FIG. 5 is an equivalence ratio distribution diagram of a combustion chamber of a medium and heavy diesel engine provided by an embodiment of the application, wherein the fuel injection included angle of the combustion chamber is 157 degrees;
FIG. 6 is an IMEP comparison graph of different oil injection angles of a combustion chamber of a medium and heavy diesel engine provided by the embodiment of the application;
FIG. 7 is a swirl ratio retention comparison diagram of a combustion chamber of a medium and heavy diesel engine provided by an embodiment of the application.
In the figure: 1-a first necking structure, 10-a first step circular arc section, 11-a step straight line section, 12-a second step circular arc section, 2-a second necking structure and 3-a bottom cavity structure.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are some embodiments of the present application, but not all 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 application.
The embodiment of the application provides a combustion chamber of a medium and heavy diesel engine, which can solve the problems of cylinder liner flushing and incomplete combustion caused by low adaptability of the combustion chamber to an injection included angle in the related art.
Referring to fig. 1, the combustion chamber of the medium and heavy diesel engine mainly comprises a first throat structure 1 and a second throat structure 2, wherein the first throat structure 1 is an annular structure, the axial cross section of the first throat structure 1 comprises a first step circular arc section 10, a step straight line section 11 and a second step circular arc section 12 from top to bottom, the first step circular arc section 10 protrudes towards the outside, the second step circular arc section 12 protrudes towards the inside, the step straight line section 11 is obliquely arranged, and the first step circular arc section 10 is connected with the second step circular arc section 12 through the step straight line section 11; the second necking structure 2 is located below the first necking structure 1, and the second necking structure 2 is vertically arranged in a cylindrical shape and is connected and transited with the bottom of the second step circular arc section 12 through an arc.
In particular, the main emissions NO of a typical diesel enginexAnd soot generation, mainly by a premixed combustion process directly related to the formation conditions and spray quality of the mixture in the combustion chamber and a diffusion combustion process mainly depending on the moving state of the air flow in the combustion chamber. That is to say, for a given injection condition, the state of the gas flow movement in the combustion chamber and its changing behavior play a decisive role in the formation of the gas mixture and its combustion process, so that NO is effectively suppressedxIn view of the emissions such as soot, it is important to control the distribution of the air flow movement in the combustion chamber, and the air flow movement state and its variation in the combustion chamber depend on the structural shapes of the intake system and the combustion chamber, which are critical and include the shape of the throat.
The throat structure of this heavy diesel engine's combustion chamber mainly includes first throat structure 1 and second throat structure 2, wherein, first throat structure 1's axial cross-section is from last to specifically including down first step circular arc section 10 step straightway 11 with second step circular arc section 12. Firstly, the matching structure design of the first reducing structure 1 and the second reducing structure 2 enables the injection included angle to be obviously increased relative to the injection included angle of the combustion chamber before, and after the injection included angle is increased, the angle of the combustion chamber which can be matched with an oil injector is correspondingly increased, so that the influence of errors generated in the process of processing and assembling on the performance of an engine is also reduced; secondly, the first step circular arc section 10, the step straight line section 11 and the second step circular arc section 12 are designed in a matched mode, so that air flow can flow and separate during combustion and generate vortex, after the vortex is generated, the air flow can generate a vortex, and oil bundles can be influenced by the air flow, so that the oil bundles are prevented from rushing to the cylinder sleeve, and the phenomenon of cylinder sleeve rushing is effectively prevented under the condition that an injection included angle is large; finally, because the combustion chamber can be fine avoid taking place the problem of impact cylinder liner, consequently can effectively avoid the engine oil to dilute or the burning soot problem of on the high side, in addition, the step straightway can guide follow the air current of second throat structure development promotes the mixture of piston upper portion air and fuel, makes the increase of in-cylinder air utilization, improves engine performance, further reduction soot discharges.
Further, the range of the inclination angle of the step straight-line segment 11 is 10-30 °.
Further, the length of the step straight line section 11 ranges from 1 mm to 3 mm.
Further, the radius of the first step circular arc section 10 and the radius of the second step circular arc section 12 range from 1 mm to 1.5 mm.
Further, the height range of the first necking structure 1 is 3-6 mm.
Specifically, because the total momentum of high-pressure injection is developed towards the cylinder sleeve, the phenomenon of flushing the cylinder sleeve can easily occur under the condition of no blocking and drainage, and after fuel is attached to the cylinder sleeve, part of the fuel can be scraped into lubricating oil by an oil ring, so that the conditions of engine oil dilution, soot emission increase and the like can be caused. The structure cooperation design among the first step circular arc section 10, the step straight-line section 11 and the second step circular arc section 12 can effectively reduce the risk of cylinder liner impact during combustion, see area A of the marked square frame in figure 3, the area A corresponds to the first necking structure, after fuel oil collides with a wall, the fuel oil can respectively develop upwards and downwards and is separated from the position of the necking, when the fuel oil develops upwards in the combustion process, a relatively obvious vortex can be generated near the first necking structure, the vortex can prevent oil bundles from developing towards the cylinder liner, the maximum injection included angle 157 degrees can be seen from a slice of a 750-degree CA combustion chamber, and the cylinder liner impact condition does not occur at the final stage of combustion.
In addition, after the combustion chamber is structurally optimized and improved compared with the combustion chamber in the related art, because fuel hardly impacts a cylinder sleeve, the problem of dilution of engine oil or high burning soot can be effectively avoided, as shown in fig. 4, two lines which are thicker and located above are soot emission conditions of the combustion chamber which is not optimized, and a thinner line which is located at the lowest is soot emission conditions of the combustion chamber which is optimized in the application, and soot can be obviously reduced according to the line which is optimized and located at the lowest in fig. 4. In addition, the oblique line section of the step can guide the airflow developed from the necking part, promote the mixing of air and fuel oil at the upper part of the piston, increase the utilization rate of air in the cylinder, improve the performance of the engine and reduce the emission of soot.
Further, the height value range of the second necking structure 2 is 1-4 mm.
Further, the value range of the ratio of the diameter of the second necking structure 2 to the maximum diameter of the bottom cavity structure 3 is 0.95-0.99.
Furthermore, the straight line segment of the second necking structure 2 can effectively improve the robustness of the combustion chamber to the injection included angle. Specifically, the drop point of the oil beam of the oil nozzle matched with the common combustion chamber needs to be close to the necking structure, so that the drop point requirement of the injection included angle which can be accepted by the conventional necking combustion chamber is very limited, and after the straight line segment of the second necking structure 2 is added to the necking part of the combustion chamber, the second necking structure 2 can be used as the drop point position of the oil beam, the acceptable range of the injection included angle is obviously enlarged, the angle of the adaptable oil injection nozzle is enlarged, and the influence of errors generated in the process of machining and assembling on the performance of the engine is reduced. In addition, as can be seen from fig. 3, 5 and 6, the injection included angle is from 150 ° to 157 °, and it can be seen that under a large included angle variation, the overall distribution is very similar, the average indicated pressure IMEP variation is also small, and the robustness of the combustion chamber to the injection included angle is good.
Further, referring to fig. 7, in comparison with most of the straight-port combustion chambers in the related art, due to the existence of the throat structure formed by the first throat structure 1 and the second throat structure 2, during combustion, in the downward process of the piston, the air flow in the cylinder can be separated, and the reverse extrusion flow is generated, so that the vortex retentivity is ensured, generally, the maximum value of the vortex occurs 10 ° CA after the top dead center, and the maximum vortex ratio is 1, the comparison between 40 ° CA and 60 ° CA after the top dead center can be seen, and the retentivity of the throat position is better. The vortex retentivity of the necking structure is good, the mixing of fuel oil and air can be better promoted, the combustion organization is better, and the engine performance is benefited. At the same time, a certain necking ratio, which is the ratio of the diameter of the second necking structure 2 to the maximum diameter of the bottom chamber structure 3, also contributes to the improvement of the holding capacity of the vortex in the cylinder.
Further, as shown in fig. 1, the combustion chamber further includes a bottom chamber structure 3, and an axial cross section of the bottom chamber structure 3 is in an omega shape, and is connected and transited with the bottom of the second throat structure 2 through an arc.
The application also provides a combustion system of the medium and heavy diesel engine, which comprises the combustion chamber. Furthermore, the combustion system further comprises a plurality of oil injection nozzles, the plurality of oil injection nozzles are arranged above the first necking structure 1 and at least partially extend into the first necking structure 1, and an included angle between each oil injection nozzle and the central axis of the combustion chamber is 73.5-78.5 degrees.
Further, the combustion chamber mainly comprises a first throat structure 1 and a second throat structure 2, wherein the first throat structure 1 is an annular structure, the axial cross section of the first throat structure 1 comprises a first step circular arc section 10, a step straight-line section 11 and a second step circular arc section 12 from top to bottom, the first step circular arc section 10 protrudes towards the outer side, the second step circular arc section 12 protrudes towards the inner side, the step straight-line section 11 is obliquely arranged, and the first step circular arc section 10 is connected with the second step circular arc section 12 through the step straight-line section 11; the second necking structure 2 is located below the first necking structure 1, and the second necking structure 2 is vertically arranged in a cylindrical shape and is connected and transited with the bottom of the second step circular arc section 12 through an arc.
In particular, the main emissions NO of a typical diesel enginexAnd soot generation, mainly by a premixed combustion process directly related to the formation conditions and spray quality of the mixture in the combustion chamber and a diffusion combustion process mainly depending on the moving state of the air flow in the combustion chamber. That is to say, for a given injection condition, the air flow movement state in the combustion chamber and its variation characteristics are pairedPlays a decisive role in the formation of the mixture and in the combustion process thereof, and therefore, in order to effectively suppress NOxIn view of the emissions such as soot, it is important to control the distribution of the air flow movement in the combustion chamber, and the air flow movement state and its variation in the combustion chamber depend on the structural shapes of the intake system and the combustion chamber, which are critical and include the shape of the throat.
The throat structure of this heavy diesel engine's combustion chamber mainly includes first throat structure 1 and second throat structure 2, wherein, first throat structure 1's axial cross-section is from last to specifically including down first step circular arc section 10 step straightway 11 with second step circular arc section 12. Firstly, the matching structure design of the first reducing structure 1 and the second reducing structure 2 enables the injection included angle to be obviously increased relative to the injection included angle of the combustion chamber before, and after the injection included angle is increased, the angle of the combustion chamber which can be matched with an oil injector is correspondingly increased, so that the influence of errors generated in the process of processing and assembling on the performance of an engine is also reduced; secondly, the first step circular arc section 10, the step straight line section 11 and the second step circular arc section 12 are designed in a matched mode, so that air flow can flow and separate during combustion and generate vortex, after the vortex is generated, the air flow can generate a vortex, and oil bundles can be influenced by the air flow, so that the oil bundles are prevented from rushing to the cylinder sleeve, and the phenomenon of cylinder sleeve rushing is effectively prevented under the condition that an injection included angle is large; finally, because the combustion chamber can be fine avoid taking place the problem of impact cylinder liner, consequently can effectively avoid the engine oil to dilute or the burning soot problem of on the high side, in addition, the step straightway can guide follow the air current of second throat structure development promotes the mixture of piston upper portion air and fuel, makes the increase of in-cylinder air utilization, improves engine performance, further reduction soot discharges.
Further, the range of the inclination angle of the step straight-line segment 11 is 10-30 °.
Further, the length of the step straight line section 11 ranges from 1 mm to 3 mm.
Further, the radius of the first step circular arc section 10 and the radius of the second step circular arc section 12 range from 1 mm to 1.5 mm.
Further, the height range of the first necking structure 1 is 3-6 mm.
Specifically, because the total momentum of high-pressure injection is developed towards the cylinder sleeve, the phenomenon of flushing the cylinder sleeve can easily occur under the condition of no blocking and drainage, and after fuel is attached to the cylinder sleeve, part of the fuel can be scraped into lubricating oil by an oil ring, so that the conditions of engine oil dilution, soot emission increase and the like can be caused. The structure cooperation design among the first step circular arc section 10, the step straight-line section 11 and the second step circular arc section 12 can effectively reduce the risk of cylinder liner impact during combustion, see area A of the marked square frame in figure 3, the area A corresponds to the first necking structure, after fuel oil collides with a wall, the fuel oil can respectively develop upwards and downwards and is separated from the position of the necking, when the fuel oil develops upwards in the combustion process, a relatively obvious vortex can be generated near the first necking structure, the vortex can prevent oil bundles from developing towards the cylinder liner, the maximum injection included angle 157 degrees can be seen from a slice of a 750-degree CA combustion chamber, and the cylinder liner impact condition does not occur at the final stage of combustion.
In addition, after the structure of the combustion chamber is optimized and improved compared with the combustion chamber in the related art, the problem of dilution of engine oil or higher burning soot can be effectively avoided because fuel hardly impacts a cylinder sleeve, and the optimized line in fig. 4 shows that the soot is obviously reduced. In addition, the oblique line section of the step can guide the airflow developed from the necking part, promote the mixing of air and fuel oil at the upper part of the piston, increase the utilization rate of air in the cylinder, improve the performance of the engine and reduce the emission of soot.
Further, the height value range of the second necking structure 2 is 1-4 mm.
Further, the value range of the ratio of the diameter of the second necking structure 2 to the maximum diameter of the bottom cavity structure 3 is 0.95-0.99.
Furthermore, the straight line segment of the second necking structure 2 can effectively improve the robustness of the combustion chamber to the injection included angle. Specifically, the drop point of the oil beam of the oil nozzle matched with the common combustion chamber needs to be close to the necking structure, so that the drop point requirement of the injection included angle which can be accepted by the conventional necking combustion chamber is very limited, and after the straight line segment of the second necking structure 2 is added to the necking part of the combustion chamber, the second necking structure 2 can be used as the drop point position of the oil beam, the acceptable range of the injection included angle is obviously enlarged, the angle of the adaptable oil injection nozzle is enlarged, and the influence of errors generated in the process of machining and assembling on the performance of the engine is reduced. In addition, as can be seen from fig. 3, 5 and 6, the injection included angle is from 150 ° to 157 °, and it can be seen that under a large included angle variation, the overall distribution is very similar, the average indicated pressure IMEP variation is also small, and the robustness of the combustion chamber to the injection included angle is good.
Further, referring to fig. 7, in comparison with most of the straight-port combustion chambers in the related art, due to the existence of the throat structure formed by the first throat structure 1 and the second throat structure 2, during combustion, in the downward process of the piston, the air flow in the cylinder can be separated, and the reverse extrusion flow is generated, so that the vortex retentivity is ensured, generally, the maximum value of the vortex occurs 10 ° CA after the top dead center, and the maximum vortex ratio is 1, the comparison between 40 ° CA and 60 ° CA after the top dead center can be seen, and the retentivity of the throat position is better. The vortex retentivity of the necking structure is good, the mixing of fuel oil and air can be better promoted, the combustion organization is better, and the engine performance is benefited. At the same time, a certain necking ratio, which is the ratio of the diameter of the second necking structure 2 to the maximum diameter of the bottom chamber structure 3, also contributes to the improvement of the holding capacity of the vortex in the cylinder.
Further, as shown in fig. 1, the combustion chamber further includes a bottom chamber structure 3, and an axial cross section of the bottom chamber structure 3 is in an omega shape, and is connected and transited with the bottom of the second throat structure 2 through an arc.
In the description of the present application, it should be noted that the terms "upper", "lower", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, which are only for convenience in describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and operate, and thus, should not be construed as limiting the present application. Unless expressly stated or limited otherwise, the terms "mounted," "connected," and "connected" are intended to be inclusive and mean, for example, that they may be fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present application can be understood by those of ordinary skill in the art as appropriate.
It is noted that, in the present application, relational terms such as "first" and "second", and the like, are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
The above description is merely exemplary of the present application and is presented to enable those skilled in the art to understand and practice the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the application. Thus, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (10)
1. A combustion chamber of a medium and heavy diesel engine, the axial section of which is omega-shaped, is characterized in that the combustion chamber comprises:
the first necking structure (1) is an annular structure, the axial section of the first necking structure (1) comprises a first step circular arc section (10), a step straight line section (11) and a second step circular arc section (12) from top to bottom, the first step circular arc section (10) protrudes towards the outer side, the second step circular arc section (12) protrudes towards the inner side, and the step straight line section (11) is obliquely arranged to connect the first step circular arc section (10) and the second step circular arc section (12);
and the second necking structure (2) is positioned below the first necking structure (1), and the second necking structure (2) is in a vertically-arranged cylindrical shape and is connected and transited with the bottom of the second step circular arc section (12) through an arc.
2. The combustion chamber of a medium and heavy duty diesel engine as set forth in claim 1 wherein: the range of the inclination angle of the step straight-line segment (11) is 10-30 degrees.
3. The combustion chamber of a medium and heavy duty diesel engine as set forth in claim 1 wherein: the length of the step straight line section (11) ranges from 1 mm to 3 mm.
4. The combustion chamber of a medium and heavy duty diesel engine as set forth in claim 1 wherein: the radius of the first step circular arc section (10) and the radius of the second step circular arc section (12) range from 1 mm to 1.5 mm.
5. The combustion chamber of a medium and heavy duty diesel engine as set forth in claim 1 wherein: the height range of the second necking structure (2) is 1-4 mm.
6. The combustion chamber of a medium and heavy duty diesel engine as set forth in claim 1 wherein: the combustor further comprises a bottom cavity structure (3), the axial section of the bottom cavity structure (3) is omega-shaped, and the bottom of the bottom cavity structure (3) is connected and transited through an arc.
7. The combustion chamber of a medium and heavy duty diesel engine as set forth in claim 6, wherein: the value range of the ratio of the diameter of the second necking structure (2) to the maximum diameter of the bottom cavity structure (3) is 0.95-0.99.
8. The combustion chamber of a medium and heavy duty diesel engine as set forth in claim 1 wherein: the height range of the first necking structure (1) is 3-6 mm.
9. A combustion system of a medium and heavy diesel engine, characterized in that it comprises: the combustion system comprising a combustion chamber according to any one of claims 1 to 9.
10. The combustion system of a medium and heavy duty diesel engine as set forth in claim 9, wherein: the combustion system comprises a plurality of oil injection nozzles, the oil injection nozzles are arranged above the first necking structure (1) and at least partially extend into the first necking structure (1), and an included angle between each oil injection nozzle and the central axis of the combustion chamber ranges from 73.5 degrees to 78.5 degrees.
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| CN202110871908.XA CN113482762A (en) | 2021-07-30 | 2021-07-30 | Combustion chamber and combustion system of medium-heavy diesel engine |
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| CN204344261U (en) * | 2014-12-18 | 2015-05-20 | 北汽福田汽车股份有限公司 | A kind of burning chamber of diesel engine |
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Application publication date: 20211008 |