A kind of CNG engine combustion chamber structure and fuel injection method thereofTechnical field
The present invention relates to the CNG engine combustion chamber structure, also relate in addition a kind of CNG engine fuel injection method, belong to the CNG field of engine combustion.
Background technique
Reduce discharging and improve the emphasis that combustion efficiency is the present engine development; The following Europe 5 that will implement, Europe 6 emission standards all need to develop new technology and meet the demands; And fuel fully rapid combustion in motor for reducing discharging, improves the combustion efficiency important in inhibiting; Meanwhile, lean combustion and the strategy that adopts CNG to act as a fuel, it reduces discharging, improves the combustion efficiency effect and has caused people's attention.
Traditional CNG motor, CNG and air are mixed into the firing chamber in intake manifold, and by plug ignition, this CNG fuel and air Mixture need higher concentration can realize igniting, need simultaneously higher ignition energy, and remaining CNG easily forms tempering phenomenon in the air flue; Meanwhile, the combustion flame propagation speed of CNG is lower, and then affects mechanical efficiency.
Summary of the invention
The object of the present invention is to provide a kind of CNG engine combustion chamber structure and fuel injection method thereof, the combustion swirl that forms when entering main combustion chamber at a high speed by the precombustion chamber air-flow improves velocity of propagation of flame and combustion efficiency greatly; Form denseer CNG-air Mixture by the CNG sparger at precombustion chamber, and by plug ignition, the high-speed and high-temperature combustion-gas flow that forms has enough energy main combustion chamber lean combustion gas that ignites, can reduce the concentration of the CNG-air Mixture of main combustion chamber, reduce discharging, improve combustion efficiency, and can prevent tempering phenomenon.
Concrete technological scheme is as follows:
A kind of CNG engine combustion chamber structure comprises the CNG sparger, and spark plug, aperture, precombustion chamber, main combustion chamber and intake duct, described precombustion chamber are arranged at the main combustion chamber top, and precombustion chamber links to each other by several apertures with main combustion chamber; Described spark plug is arranged at the main combustion chamber top, and described precombustion chamber is positioned at the spark plug next door; Described CNG sparger is arranged at the precombustion chamber top, and it is used for forming the CNG-air Mixture at precombustion chamber, and described spark plug is for the CNG-air Mixture of lighting precombustion chamber, and combustion gas spray into main combustion chamber through small holes; Described intake duct connects main combustion chamber, and for air inlet in the firing chamber.
Further, described precombustion chamber is a Small Combustion chamber, and volume is about 1% of main combustion chamber.
Further, described a plurality of apertures are in a certain angle, make combustion gas form combustion swirl when small holes enters main combustion chamber.
Further, described CNG sparger is a low-pressure CNG sparger, and it is used for spraying into a small amount of CNG to precombustion chamber, forms the CNG-air Mixture at precombustion chamber.
The fuel injection method of above-mentioned CNG engine combustion chamber structure, adopt following steps:
(1) aspirating stroke: IO Intake Valve Opens, thin CNG-air Mixture enters main combustion chamber by intake duct, and enters precombustion chamber by aperture;
Precombustion chamber little residue part waste gas mixes with thin gas-air mixture because suction function enters main combustion chamber;
(2) compression stroke: IC Intake Valve Closes, piston stroking upward, in compression stroke latter stage, ECU control CNG sparger sprays into an amount of combustion gas to precombustion chamber, increases precombustion chamber combination gas concentration;
(3) expansion stroke: when piston moved to top dead center, the precombustion chamber plug ignition was lighted precombustion chamber CNG-air Mixture;
The high-temperature gas of burning expands rapidly, enters at a high speed main combustion chamber through aperture, forms eddy current at main combustion chamber, drives the thin CNG-air Mixture of main combustion chamber and burns rapidly, the acting of expanding;
(4) exhaust stroke: exhauxt valve opens, piston stroking upward, waste gas is discharged.
Further, in the step (2), control CNG jet pressure prevents that a large amount of CNG jet pressures are excessive, and denseer CNG-air Mixture enters main combustion chamber too early in a large number in a large amount of precombustion chambers.
Compare with present prior art, the present invention designs a small-sized precombustion chamber in spark plug place above main combustion chamber, design simultaneously a low-pressure CNG sparger and spray into a small amount of CNG to precombustion chamber, form denseer CNG-air Mixture at precombustion chamber, designing simultaneously several apertures in a certain angle links to each other with main combustion chamber, light precombustion chamber mixed combustible gas body, the high-speed and high-temperature combustion gas that form enter at a high speed main combustion chamber through aperture, and form a large amount of combustion swirls, driving the thin CNG-air Mixture of main combustion chamber burns rapidly, thereby realize reducing discharging, improve combustion efficiency.
1. precombustion chamber high-speed and high-temperature combustion gas enter at a high speed main combustion chamber through aperture, and form a large amount of combustion swirls, the main combustion chamber flame propagation speed, and then improve combustion efficiency, improved the slow shortcoming of CNG fuel flame velocity of propagation;
2. because precombustion chamber high-speed and high-temperature combustion gas energy is enough, high-speed high-temperature gas can form a large amount of combustion swirls when aperture enters main combustion chamber simultaneously, main combustion chamber CNG-air Mixture concentration can reduce, can realize lean combustion at main combustion chamber, reduce discharging, improve combustion efficiency, can prevent the air flue tempering phenomenon simultaneously.
Description of drawings
Fig. 1 is the chamber structure schematic diagram
Embodiment
The below describes the present invention with reference to the accompanying drawings, and it is a kind of preferred embodiment in the numerous embodiments of the present invention.
With reference to accompanying drawing 1, this system is mainly by 1. gas injector; 2. spark plug; 3. aperture; 4. precombustion chamber; 5. main combustion chamber; 6. intake duct forms.
(1) precombustion chamber is a Small Combustion chamber, is positioned at by the spark plug of main combustion chamber top, and small volume, volume are about 1% of main combustion chamber;
(2) precombustion chamber links to each other by several apertures with main combustion chamber, and aperture is in a certain angle, is convenient to form eddy current;
(3) precombustion chamber is designed with low-pressure CNG sparger, by the CNG sparger a small amount of CNG is sprayed into precombustion chamber, around the precombustion chamber spark plug, form denseer gas-air mixture, control CNG jet pressure, prevent that a large amount of CNG jet pressures are excessive, denseer CNG-air Mixture enters main combustion chamber too early in a large number in a large amount of precombustion chambers;
(4) a part of CNG combustion gas forms thin CNG-air Mixture and enters main combustion chamber by intake duct by spraying into intake manifold, and burns rapidly by precombustion chamber high-speed and high-temperature combustion-gas flow drive main combustion chamber lean combustion gas;
(5) precombustion chamber is designed with spark plug, by the denseer CNG gas-air mixture of spark ignitor precombustion chamber, and by aperture the high-speed and high-temperature combustion gas are sprayed into main combustion chamber, by setting little hole number and angle, in main combustion chamber, form combustion swirl, drive the burning of main combustion chamber lean mixture CNG combustion gas rapid diffusion, the pushing piston acting.
By above the CNG engine chamber, designing precombustion chamber, and design several apertures in a certain angle and link to each other with main combustion chamber, precombustion chamber is designed with the CNG sparger simultaneously, form denseer CNG-air Mixture by the CNG sparger at precombustion chamber, by spark ignitor precombustion chamber inflammable mixture, through small holes the high-speed and high-temperature combustion gas are sprayed into main combustion chamber, and form a large amount of combustion swirls, because the high temperature and high speed combustion-gas flow energy that precombustion chamber forms enough drives the rapid combustion of main combustion chamber lean combustion mixed gas, improved velocity of propagation of flame, thereby can realize lean combustion at main combustion chamber, reduce discharging, improve combustion efficiency, and can prevent tempering phenomenon.
The combustion jet process is preferably as follows:
1, aspirating stroke: IO Intake Valve Opens; thin CNG-air Mixture enters main combustion chamber 5 by intake duct 6; and enter precombustion chamber 4 by aperture 3; simultaneously because suction function; precombustion chamber 4 little residue part waste gas enter main combustion chamber 5; mixes with thin gas-air mixture, owing to the precombustion chamber volume is about main combustion chamber volume about 1%, affect also very little;
2, compression stroke: IC Intake Valve Closes, piston stroking upward, in compression stroke latter stage, ECU control CNG sparger 1 sprays into an amount of combustion gas to precombustion chamber 4, increases precombustion chamber combination gas concentration;
3, expansion stroke: when piston moves to top dead center, 2 igniting of precombustion chamber spark plug, light precombustion chamber CNG-air Mixture, the high-temperature gas of burning expands rapidly, enter at a high speed main combustion chamber through aperture 3, form violent eddy current at main combustion chamber 5, drive the thin CNG-air Mixture of main combustion chamber and burn rapidly, the acting of expanding;
4, exhaust stroke: exhauxt valve opens, piston stroking upward, waste gas is discharged;
CNG-air Mixture that the spark ignitor precombustion chamber is flammable, precombustion chamber flame expands rapidly, the high-temp combustion air-flow enters main combustion chamber through several apertures in a certain angle at a high speed, and form a large amount of combustion swirls at main combustion chamber, drive the thin CNG-air gas mixture of main combustion chamber and burn rapidly, the acting of expanding.Compare with conventional engines, this scheme has advantages of flame propagation speed, simultaneously by the little hole number of design and angle, guiding precombustion chamber high-temperature high-speed airflow can form strong combustion swirl when entering main combustion chamber, fuel is better mixed with air, fuel combustion is got more complete, reduce discharging and improve fuel efficiency.
In addition can be enough owing to precombustion chamber high temperature and high speed gas energy, main combustion chamber CNG-air combination gas concentration can reduce, thereby realizes lean combustion, thereby reduces discharging, improves combustion efficiency, and can avoid occurring the backfiring in intake manifold phenomenon.
The above has carried out exemplary description to the present invention by reference to the accompanying drawings; obviously specific implementation of the present invention is not subjected to the restriction of aforesaid way; as long as the various improvement of having adopted method design of the present invention and technological scheme to carry out; or directly apply to other occasion without improvement, all within protection scope of the present invention.