CN109252972A - A kind of combustion chamber for natural gas engine - Google Patents
A kind of combustion chamber for natural gas engine Download PDFInfo
- Publication number
- CN109252972A CN109252972A CN201810921735.6A CN201810921735A CN109252972A CN 109252972 A CN109252972 A CN 109252972A CN 201810921735 A CN201810921735 A CN 201810921735A CN 109252972 A CN109252972 A CN 109252972A
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- China
- Prior art keywords
- throat
- piston
- tapered portion
- cylinder head
- combustion chamber
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Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02F—CYLINDERS, PISTONS OR CASINGS, FOR COMBUSTION ENGINES; ARRANGEMENTS OF SEALINGS IN COMBUSTION ENGINES
- F02F3/00—Pistons
- F02F3/26—Pistons having combustion chamber in piston head
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02F—CYLINDERS, PISTONS OR CASINGS, FOR COMBUSTION ENGINES; ARRANGEMENTS OF SEALINGS IN COMBUSTION ENGINES
- F02F3/00—Pistons
- F02F3/24—Pistons having means for guiding gases in cylinders, e.g. for guiding scavenging charge in two-stroke engines
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02F—CYLINDERS, PISTONS OR CASINGS, FOR COMBUSTION ENGINES; ARRANGEMENTS OF SEALINGS IN COMBUSTION ENGINES
- F02F3/00—Pistons
- F02F3/28—Other pistons with specially-shaped head
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- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Combustion Methods Of Internal-Combustion Engines (AREA)
Abstract
The present invention relates to a kind of combustion chambers for natural gas engine, for the closed area being made of cylinder jacket, piston and cylinder head, spark plug is arranged in the cylinder head of combustion chamber medium position, and cylinder head bottom is flat, it is characterised in that, rough shape is presented in top land, top land includes tapered portion, throat and expansion, is extended from piston centreline along piston radial to outside from inside to outside using piston centreline as symmetry axis, sectional area is gradually reduced, and is tapered portion；Tapered portion is ended to throat, and throat section product is minimum, is extended from throat along piston radial to outside, and sectional area becomes larger as expansion, and the cross section curve of tapered portion is designed according to Vito Xin Siji formula.
Description
Technical field
The present invention is a kind of chamber structure for natural gas engine, is related to technical field of engines, specifically relates to
And the design of engine chamber.
Background technique
In recent years, increasingly serious with the increasingly consumption of petroleum and environmental problem, many countries are all in search for oil
Alternate resources.Due to the good thermodynamic property of natural gas, natural gas is increasingly valued by people.Major part day at present
Right gas engine is all that can not sufficiently adapt to natural gas from existing petrol engine and diesel engine simple refit
Fuel, and natural gas squish flow intensity in cylinder is little, flowing velocity is lower, to generate some abnormal burnings, shortens
Service life of engine.To be advanced optimized to natural gas engine, it is necessary to make and targetedly design, can especially close
The design for managing tissue burning is adapted natural gas and engine structure.
The burning of engine internal fuel carries out in the combustion chamber, is the most important part of engine.And engine
The planform of combustion chamber has been largely affected by the flowing and flame transmission of fuel mixture.Therefore, designing one has
The combustion chamber for helping fuel flowing and burning is of crucial importance.And the combustion chamber of engine is by cylinder jacket, piston and cylinder head group
At closed area, not only can change the geomery of cylinder head, can also by change piston crown, to change air-flow
Movement, to optimize flowing and the combustion position of combustion chamber fuel.
In the movement of fluid, convergent nozzle can accelerate the flow velocity of fluid.Some sides by Nozzle Design combustion chamber
Case, most of is the pre-burning in premixed combustion room, then is sprayed into main chamber by high-pressure pump, to optimize combustion position, in this way
Pressure, which is provided, by the external world also consumes additional energy.Therefore, if burning by fuel itself and making to achieve the effect that injection,
It can be further improved the utilization rate of fuel.
Summary of the invention
The purpose of the present invention is designing a kind of chamber structure for natural gas engine, based on conventional engines
Structure improves engine, and technical method is as follows:
A kind of combustion chamber for natural gas engine, for the closed area being made of cylinder jacket, piston and cylinder head, fire
Hua Sai is arranged in the cylinder head of combustion chamber medium position, and cylinder head bottom is flat, which is characterized in that top land presents concave-convex
Uneven shape, top land include tapered portion, throat and expansion using piston centreline as symmetry axis from inside to outside,
It is extended from piston centreline along piston radial to outside, sectional area is gradually reduced, and is tapered portion；Tapered portion is ended to larynx
Portion, throat section product is minimum, is extended from throat along piston radial to outside, sectional area becomes larger as expansion, tapered portion
The cross section curve divided is designed according to Vito Xin Siji formula.
Preferably, the cross section curve of tapered portion designs according to the following formula:
Wherein, d1Distance for piston centre point to cylinder head bottom, d2For the distance of throat to cylinder head bottom, l is to live
Center line is filled in the distance of throat, and for design position to the distance of throat, d (x) is tapered portion section when x is design section curve
To the distance of cylinder head bottom at the x of Curve Design position.
Distance of the piston centreline to throat:
α is the angle of flare of expansion；
In throat position, piston is d at a distance from cylinder head2=dc+ Δ d, dc are the quenching distance of equivalent proportion gaseous mixture,
Δ d is corrected range.
Expansion uses 6-12 ° of angle of flare α.
Combustion chamber tapered portion and expansion volume ratio V1/V2=25%/75%.
According to above-mentioned design, that is, it can be designed the geomery at a certain axial cross section position of top land, then around piston
Center line rotation can be obtained entire piston crown geomery.In addition, rounded corner is answered in the junction in each face.With the prior art
It compares, the beneficial effects of the present invention are:
The present invention strengthens the squish flow effect in compression process by the shape of tapered portion and expansion.In addition, fortune
With the principle of similar convergent nozzle, the compression of the combustion expansion pressure and expansion of tapered portion is whole in engine combustion process
Pressure generates pressure difference, so that gaseous mixture be made in engine to be ejected into expansion from tapered portion.In addition, due to tapered portion
Divide becoming smaller for gaseous mixture subsonic flow sectional area, accelerate air flow rate and flame propagation velocity, shorten delay period,
To keep fuel combustion more abundant.
Plain combustion chamber's heat liberation rate, heat release rate is substantially increased in 20%-30%, it is desirable to keep air-flow big before heat liberation rate, heat release rate is substantially increased
Amount is ejected into expansion by tapered portion, therefore designs the certain proportion that tapered portion accounts for total combustion chamber volume, puts burning
Heat more occurs in expansion.The present invention, can according to the volume ratio of tapered portion and the design of expansion heat liberation rate, heat release rate rule
To improve the exothermal effect of fuel combustion.
The present invention sprays fuel by jet pipe by energy caused by fuel burning itself, eliminates to external energy
Dependence, more fully improve the utilization rate of fuel.
Detailed description of the invention
Fig. 1 is combustion-chamber shape scale diagrams of the present invention
Fig. 2 is to design tapered portion schematic diagram according to Vito Xin Siji formula
Fig. 3 is compression travel air flow status schematic diagram
Fig. 4 is air-flow flow schematic diagram after spark plug sparking
In figure:
1- inlet valve 2- spark plug 3- exhaust valve 4- cylinder head 5- throat 6- expansion 7- tapered portion 8- is living
Plug
Specific embodiment
The mentality of designing of the chamber structure for natural gas engine of the invention is introduced first, and combustion chamber is by gas
The closed area of cylinder sleeve, piston and cylinder head composition.Spark plug is arranged in the cylinder head of combustion chamber medium position.Cylinder head bottom
Portion is flat, and rough shape is presented in top land.Wherein, top land by about the symmetrical converging transition of piston centre,
Throat and expansion segment composition.It is extended from piston centreline along piston radial to outside, sectional area is gradually reduced, and is converging transition.Gradually
Contracting section is ended to throat, and throat section product is minimum, is extended from throat along piston radial to outside, sectional area becomes larger as expansion
Section.Its various pieces uses following design method:
Converging transition is similar to convergent nozzle, therefore by the design method of convergent nozzle.The curve of converging transition according to Vito it is pungent this
The design of base formula:
Wherein, d1Distance for piston centre point to cylinder head bottom, d2For the distance of throat to cylinder head bottom, l is to live
Center line is filled in the distance of throat, and for design position to the distance of throat, d (x) is converging transition Curve Design position when x is design curve
Set the distance at x to cylinder head bottom.
Empirically formula designs the length of converging transition:
α is the angle of flare of expansion segment
In throat position, piston is d at a distance from cylinder head2=dc+ Δ d, dc are the quenching distance of equivalent proportion gaseous mixture,
Δ d is corrected range.
Expansion segment uses 6-12 ° of angle of flare α.According to piston radius and previous designs, expansion segment can be designed that
Key dimension.
In addition, making combustion chamber converging transition and expansion segment volume ratio V1/V2=25%/75%,
Wherein, Rp is piston radius
According to above-mentioned design, that is, it can be designed the geomery at a certain axial cross section position of top land, then around piston
Center line rotation can be obtained entire piston crown geomery.In addition, rounded corner is answered in the junction in each face.
Present invention is further described in detail with reference to the accompanying drawings and detailed description, but the invention is not limited to
This specific embodiment, this description are not intended to limit the invention.
Fig. 1 is chamber structure schematic diagram of the present invention, and spark plug 2 is arranged in the middle part of combustion chamber.4 bottom flat of cylinder head,
Rough shape is presented in top land, and the shape of the two determines the shape of combustion chamber.Top land by tapered portion 7,
Throat 5 and expansion 6 form.Have between throat 5 and 4 bottom of cylinder head or inlet valve 1 and exhaust valve 3 it is certain away from
From, occur to hit to prevent air-stop gate and piston and it is narrow lead to flame quenching, but in the case where meeting aforementioned condition, this distance will be use up can
Can be small, in order to constitute narrow air flow passage.Tapered portion 7 and expansion 6 and cylinder head bottom 4 or valve it
Between distance it is relatively large, be the main positions of fuel combustion.In addition, rounded corner between 8 side disc of expansion 6 and piston.
A kind of design scheme is now provided, is designed according to formula, if piston diameter is 70mm, piston is 3mm with cylinder head distance d,
When angle α is 10 °, d1=7mm in Fig. 1, the tapered curve of l=13mm, tapered portion is determined by Vito Xin Siji formula, according to
Some position substitutes into the design of Vito Xin Siji formula, it can be deduced that the distance of the position to cylinder head bottom to the distance x of throat
D, the distance determine the shape of curve.Fig. 2 is to design tapered portion schematic diagram according to Vito Xin Siji formula.Fig. 3 is piston
Simulation model for mixing gases flows schematic diagram in compression travel middle cylinder.Fig. 4 is gaseous mixture flow schematic diagram in spark plug sparking after-burner.
In engine operation process, after 1 air inlet of inlet valve, compression travel is carried out.When piston 8 moves upwards, due to
Used in the extruding of piston 8, the indoor air-flow that burns flow to tapered portion 7 and enlarged portion since the segmentation of throat 5 is flowed toward both sides
Divide 6 and generates the squish flow of some strength, such as Fig. 3.At this point, fuel is largely focused in tapered portion 7 and expansion 6.
When spark plug 2 is lighted a fire, the gaseous mixture in the tapered portion 7 immediately below spark plug 2 is lighted first, forms one
A fireball increases cylinder temperature and pressure sharply, and pressure is obviously greater than compression end of a period pressure, thus flame forming part
Pressure difference is generated with throat, and due to the flame combustion expansion in tapered portion, forces what is do not burnt in tapered portion 7 to mix
It closes gas and expansion 6 is sprayed to by narrow channel.Gas is from tapered portion 7 toward when the movement of slype throat 5, and sectional area is not
It is disconnected to reduce, it is equivalent to the principle of convergent nozzle, the flowing velocity of air-flow constantly increases.In addition, due to electronic spark advance, spark plug 2
Arcing makes mixture combustion in tapered portion 7, and piston 8 still has fraction distance with top dead centre and continues up at this time, because
This, the effect guided by the air-flow of slype due to throat 5 strengthens the squish flow intensity of expansion 6, such as Fig. 4.Due to
Air-flow velocity increases, the reinforcement of squish flow intensity, therefore can accelerate flame propagation velocity, the indoor combustion case of optimization burning.
After combustion expansion process, exhaust gas is discharged by exhaust valve 3, and engine completes a circulation.
To sum up, the present invention is a kind of chamber structure for natural gas engine, main to consider to burning indoor air flow
The influence of flowing and law of heat release are to design piston crown geomery.With the chamber structure, can reinforce squeezing
Effect is flowed, air flow rate and flame propagation velocity, the indoor combustion case of optimization burning are accelerated.
Claims (5)
1. a kind of combustion chamber for natural gas engine, for the closed area being made of cylinder jacket, piston and cylinder head, spark
Plug is arranged in the cylinder head of combustion chamber medium position, and cylinder head bottom is flat, which is characterized in that bumps are presented not in top land
Flat shape, top land using piston centreline as symmetry axis, from inside to outside include tapered portion, throat and expansion, by
Piston centreline is extended along piston radial to outside, and sectional area is gradually reduced, and is tapered portion；Tapered portion is ended to throat,
Throat section product is minimum, is extended from throat along piston radial to outside, and sectional area becomes larger as expansion, tapered portion
Cross section curve is designed according to Vito Xin Siji formula.
2. combustion chamber according to claim 1, which is characterized in that the cross section curve of tapered portion is set according to the following formula
Meter:
Wherein, d1Distance for piston centre point to cylinder head bottom, d2For the distance of throat to cylinder head bottom, l is in piston
Heart line is to the distance of throat, and for design position to the distance of throat, d (x) is tapered portion cross section curve when x is design section curve
To the distance of cylinder head bottom at design position x.
3. combustion chamber according to claim 1, which is characterized in that the distance of piston centreline to throat:
α is the angle of flare of expansion；
In throat position, piston is d at a distance from cylinder head2=dc+ Δ d, dc are the quenching distance of equivalent proportion gaseous mixture, and Δ d is
Corrected range.
4. combustion chamber according to claim 1, which is characterized in that expansion uses 6-12 ° of angle of flare α.
5. combustion chamber according to claim 1, which is characterized in that combustion chamber tapered portion and expansion volume ratio V1/V2
=25%/75%.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810921735.6A CN109252972A (en) | 2018-08-14 | 2018-08-14 | A kind of combustion chamber for natural gas engine |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810921735.6A CN109252972A (en) | 2018-08-14 | 2018-08-14 | A kind of combustion chamber for natural gas engine |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN109252972A true CN109252972A (en) | 2019-01-22 |
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ID=65050136
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201810921735.6A Pending CN109252972A (en) | 2018-08-14 | 2018-08-14 | A kind of combustion chamber for natural gas engine |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN109252972A (en) |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1932256A (en) * | 2005-09-15 | 2007-03-21 | 马自达汽车株式会社 | Combustion chamber structure for sparkignition engine |
| JP2007162631A (en) * | 2005-12-15 | 2007-06-28 | Toyota Motor Corp | Control device of internal combustion engine |
| JP2011214557A (en) * | 2010-04-02 | 2011-10-27 | Mitsubishi Electric Corp | Cylinder injection type spark ignition internal combustion engine |
| CN103835803A (en) * | 2014-02-24 | 2014-06-04 | 大连理工大学 | Collision shunt combustion chamber of diesel engine |
-
2018
- 2018-08-14 CN CN201810921735.6A patent/CN109252972A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1932256A (en) * | 2005-09-15 | 2007-03-21 | 马自达汽车株式会社 | Combustion chamber structure for sparkignition engine |
| JP2007162631A (en) * | 2005-12-15 | 2007-06-28 | Toyota Motor Corp | Control device of internal combustion engine |
| JP2011214557A (en) * | 2010-04-02 | 2011-10-27 | Mitsubishi Electric Corp | Cylinder injection type spark ignition internal combustion engine |
| CN103835803A (en) * | 2014-02-24 | 2014-06-04 | 大连理工大学 | Collision shunt combustion chamber of diesel engine |
Non-Patent Citations (1)
| Title |
|---|
| 王新月等: "《热力学与气体动力学基础》", 31 August 2004 * |
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| PB01 | Publication | ||
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Application publication date: 20190122 |