RU2626611C2 - Two-stroke internal combustion engine with highest technical-economical and environmental criterial parameters and electronic control of accumulated fuel injection system of large fraction composition - Google Patents

Abstract

FIELD: engines and pumps.

SUBSTANCE: engine contains a housing with a cylinder - 1, with tangential outlet windows-slots - 2 around its diameter, a gas collector annular cavity - 3, a piston-slide valve - 4, a cylinder head - 5, a combustion chamber - 6, an air-fuel supply channel - 7, a swirler - 8, nozzles 9, an intake valve - 10 and a candle - 11. The engine provides the best criterial, resource-saving, technical-economic and environmental parameters, reliability and durability of all components.

EFFECT: higher efficiency of engine operation.

5 dwg

Description

The invention relates to the problem of improving the criteria for piston internal combustion engines (ICE) and may find use in engine building.

The criteria for ICE are:

1. Resource saving:

- specific mass power - N _m , kg / kW;

- effective specific fuel consumption - g _e , g / kW⋅h;

2. Dynamic - adaptability and throttle response;

3. Environmental - according to the content of standardized toxic components of exhaust gases:

- nitrogen oxides - NO _x ;

- carbon monoxide - CO;

- unburned fuel - CH;

- carbon black - C.

Currently, there is no piston engine with all the best criteria parameters at the same time. The toxicity of all of them is significantly higher than the standards even when installing neutralizers.

Engines with the best resource-saving specific mass power are gas two-stroke engines, which are discontinued due to high toxicity and high fuel consumption.

A technical solution is known in which an attempt is made in a carbureted two-stroke gasoline engine with the best N _m to improve the second resource-saving parameter - g _e , the worst among piston ICEs (up to 600 g / kW⋅h) by the separate supply of fuel and air and replacing the carburetor power system of a two-stroke engine, electronically controlled injection system (two-stroke carburetor internal combustion engines. / V.M. Kondratov, Yu.S. Grigoryev, V.V. Tupov et al. - Mechanical Engineering, 1990, p. 47-48).

The engine comprises a cylinder, a piston installed therein, a cylinder head with a combustion chamber and spark plugs, a fuel injector mounted obliquely in the cylinder wall, in which the inlet and outlet purge windows are made. In this engine, instead of a carburetor, an injector is installed in the inlet tract (window), the fuel supply through which is carried out by the electronic ECM control unit before the inlet window is blocked by a spool-piston. This solution reduces the resistance of the intake tract (there is no carburetor diffuser that creates resistance). This leads to an increase in the filling coefficient η _v , and therefore to the possibility of increasing the specific mass power, but does not solve economic and environmental problems, because does not exclude the release of fuel into the exhaust windows during purging.

Known two-stroke engine with an ECM with the installation of the nozzle in the combustion chamber and the formation of a recess in the piston bottom (US patent 6338327, IPC F02B 23/10, publ. 15.01.2002), containing the block head, housing, nozzle, connecting rod, piston, intake and exhaust windows, spark plug. This engine provides separate air and fuel supply, fuel injection after closing the exhaust window into a spherical recess in the piston crown. With these constructive measures, an increase in efficiency is achieved by eliminating fuel emissions during purging and an attempt is made to increase efficiency due to the layered method of mixture formation (hereinafter referred to as PSO).

The main disadvantage of the known engine is the high heterogeneity of the air-fuel mixture during PSSO and fuel combustion, in which the local values of the coefficient of excess air - α _l during loop blowing ranges from α _l = 0.95 ÷ 2.0, predetermining a large range of working fluid temperature T _RT = 2500 ÷ 1400 K, and the high formation of nitrogen oxides at T _{RT is} higher than the activation temperature of the oxidation reaction of N ₂ with atmospheric oxygen (T _act ≈ 1500 K). Another disadvantage of installing the nozzle in the combustion chamber is that it is located in the zone of high temperatures (up to 2500 K) and pressures (up to 7 MPa). This reduces its reliability and durability.

In addition, the installation of the nozzle in the high pressure zone determines the need to increase the fuel pressure in front of the nozzle nozzle openings by 0.3 ÷ 0.4 MPa more than the maximum pressure of the working fluid in the combustion chamber - P _m max.

This requires the creation of a new battery system for supplying a high constant pressure engine (P _m = 8.3 ÷ 8.5 MPa) and units designed for this pressure.

Known two-stroke gasoline engine with a crank-chamber air purge, a battery fuel supply system, electronic control of the separate supply of fuel and air into the cylinder and microprocessor spark ignition (RU 2344299 C1, publ. 20.01.2009).

The engine comprises a cylinder, in the wall of which inlet and outlet windows are made, a fuel nozzle mounted obliquely in the cylinder wall, a piston (with a cylindrical recess in the bottom) that acts as a spool, a cylinder head and a candle.

Such a technical solution to increase fuel economy and improve environmental performance, reliability of ignition and sustainable combustion, as well as to protect the nozzle from high temperature and pressure is achieved by separate supply of fuel and air to the cylinder during loop (loop) purging by means of a constructive forced turbulent air flow twisted structurally in the inlet windows, providing volume-film mixture formation (hereinafter OPSSO) and combustion of the fuel-air mixture.

The advantages of a loop (contour) gas exchange scheme are:

- simplicity of engine design, lack of valves and their drive.

- Organization of crank-chamber filling of the engine cylinder with air when purging without an external supercharger.

The disadvantages of this engine are:

- low quality of cylinder cleaning in a loop (contour) gas exchange scheme;

- the appearance of a stagnant zone above the piston with a large angle of inclination of the axes of the inlet windows - 45 ÷ 50 °, which makes the forced intensification of mass transfer ineffective;

- a separate supply of purge air (instead of the fuel-air-oil mixture), through the ICE pan creates the problem of lubricating the crankshaft bearings;

- the organization of the OPSSO, due to the presence of windproof zones and a large heterogeneity of the fuel-air mixture due to two-stage combustion of the mixture with a large range of local values α _l = 0.95 ÷ 2.0, which determines a high range T _cr = 2500-1400 K and the formation nitrogen oxides;

- high consumption of "clean" air when filling the cylinder during a crank-chamber loop (loop) purge through transversely arranged inlet and outlet windows due to its large removal in the mixture with exhaust gases (hereinafter referred to as exhaust gas) when cleaning the cylinder.

This design is the closest to the proposed technical essence and is taken as the closest analogue.

The invention is based on the technical task of developing a single-cycle engine workflow with all the best criteria, resource-saving, technical, economic and environmental parameters, reliability and durability of all nodes.

The solution to this problem is achieved by the fact that in a single-cycle engine with electronic control of separate supply of the fuel-air mixture and cleaning the cylinder from exhaust gas, the fuel supply nozzle is installed in the air-fuel supply channel of the cylinder head, and the air-fuel supply channel is located at an angle β = 75 ÷ 80 ° to the valve axis and tangential inlet to the swirl.

The location of the nozzle in the zone of low temperature (≈ 300 ÷ 350 K) and boost pressure P _a ≈0.15 ÷ 0.2 MPa in the air-fuel supply channel improves the reliability and durability of the nozzle.

The low level of pressure in the air-fuel supply channel and low requirements for the quality of the sprayed fuel predetermine the use of an accumulator power supply system for low-pressure fuel, close to the pressure in the injection system Pm = 0.3 ÷ 0.5 MPa, which reduces the cost of units (pump, nozzles, pipelines, etc.) and determines the simplicity of their design.

An electromagnetic valve controlled by the controller with a bevel β ₁ = 10 ÷ 15 ° to its axis forms a film-vortex method of intensification of mixture formation and heat and mass transfer in the combustion chamber. The small swirl angle of the swirl and the equal chamfer angle β ₁ ≈ 10 ÷ l5 ° creates a tangential air flow, which, when expanding at the inlet of the combustion chamber, is almost perpendicular to the cylinder axis, which creates a layered air flow at axial velocity V _x → 0 (without mixing with displaced combustion products) displacement of combustion products.

An increase in the resource-saving criterion parameter - specific mass power N _{m is} achieved due to the intensification of heat and mass transfer during the film-vortex method of burning a poor mixture with α = 1.5-2, dissipation of radiant energy into the heat energy of the working fluid and reduction of heat transfer to the cooling system.

Outlet windows-slots (hereinafter outlet windows) are made along the entire perimeter (diameter) of the cylinder with a window height h equal to ≈0.063 of the piston stroke S, tangentially to the circumference of the cylinder circumference and at an angle of faces β ₂ = 75 ÷ 80 ° to the cylinder axis.

Improving fuel economy is ensured by the separate supply of the air-fuel lean mixture swirling in a swirl through the inlet valve to the engine cylinder and cleaning it of combustion products with electronic control of the fuel supply by the nozzle and the moment the valve opens and closes at various high-speed engine operation modes ensuring maximum filling (η _v ) and the minimum amount of residual gases (η _og ) in a fresh charge with valve-slot direct-flow blowing.

Improving environmental performance (reducing the formation of nitrogen oxides NO _x ) is achieved through structurally organized forced turbulent / kg and T _act = 1500 K excess coefficient

air not lower than α = 1.5. This, with a large excess of oxygen, predetermines a decrease in the content of other toxic normalized components: CO, CH and soot to the level of Euro-5.

Reducing the maximum temperature of the combustion products to T _cr = l500 K reduces the proportion of radiant energy transmitted to the wall of the COP and the cylinder, and a high degree of blackness fuel film vapor deposition at a film-vortex method of mixing, increase the dissipation of radiant energy in the working fluid, increasing the heat stake energy transferred to it by heat transfer with the characteristics of turbulent heat and mass transfer (λ _t , μ _t , α _t ), many times greater than diffusion heat and mass transfer (λ _t , μ _t , α _t ). This leads to a decrease in wall temperature and heat dissipation into the environment.

The use of a gasoline fraction of fuel with a wide fractional composition due to a reduction in the ignition delay period reaching δ = 0.2 to δ → 0 with spark ignition regulated by the ECM controller improves the technical (stiffness, maximum pressure, etc.) engine performance.

The presented constructive solutions ensure the achievement of the goal:

1. Creation of an engine with all the best criteria parameters:

- specific mass power - N _m (kg / kW);

- specific effective fuel consumption of a wide fractional composition (g _e , g / kW⋅h);

- specific content of standardized components in the exhaust gas up to Euro - 5 (g / kW⋅h).

2. Improving the reliability and durability of the nozzle, spark plug and parts of the cylinder-piston group.

3. The use of fuel of a wide fractional composition will reduce the requirements for physicochemical (antiknock and other) properties, production technology and expand the fuel base of hydrocarbon fuel, including gas condensates.

The essence of the invention is illustrated by drawings:

FIG. 1 is a general diagram of a single cycle engine;

FIG. 2 - horizontal section AA along the air-fuel supply channel;

FIG. 3 - vertical section of the fuel - air channel;

FIG. 4 - section of the cylinder at the outlet windows;

FIG. 5 is a section along the outlet window.

A single-cycle two-stroke engine contains a housing with a cylinder - 1, along the entire diameter of which there are tangential exhaust windows - 2 with a slope in height h of the faces (equal to half the height of the windows with a crank chamber purge) equal to the swirl angle of the exhaust gas flow to reduce hydraulic losses at the inlet in the annular cavity of the gas collector - 3, connected to the purge pump (not shown in Fig.), the piston-spool - 4 and the cylinder head - 5 with the combustion chamber - 6, structurally formed in the air-fuel supply channel - 7 swirler - 8 and nozzles - 9, as well as the inlet valve - 10 and the candle -11.

The engine operates as follows.

When the piston-spool - 4 is moved from the top dead center (hereinafter TDC) to the bottom dead center (hereinafter BDC), exhaust ports open at the stroke of the stroke (expansion) - 2 and combustion products under pressure begin to enter the annular cavity of the gas collector - 3 and further to the turbine of the boost unit (turbocharger).

The location of the purge windows in the BDC with valve-slotted straight-through purge allows to increase the total area of the bore sections of the exhaust windows and reduce the height of the slots, and hence the proportion of the lost piston stroke - S, which does not impair the cleaning of the cylinder from exhaust gases. When the pressure in the cylinder - 1 is reduced to a pressure lower than the air pressure in front of the inlet valve - 10 in the swirler - 8, the inlet valve - 10 opens, through which the air enters through the air-fuel supply channel - 7 and swirls in the swirl - 8 through the air-fuel supply channel - 7 in the cylinder - 1, displacing combustion products.

The cylinder cleaning ends after the piston-spool shuts off - windows - 2 on the compression stroke (movement from BDC to TDC) with the intake valve open - 10. The electronic control unit injects fuel with the nozzle - 9 into the air-fuel supply channel - 7. The mixture is twisted with a swirl - 8 and through the valve - 10 due to centrifugal forces, fuel is applied to the surface of the combustion chamber and the upper part of the cylinder (approximately to the TDC of the first piston ring), forming a strong film on them. The moment of cutoff of the fuel supply and then closing of the intake valve is determined by the electronic control unit depending on the load and high-speed operation of the internal combustion engine.

During turbulent (vortex) movement of the air stream washing the surface of the fuel film, with which evaporation and vapor formation begins, mass transfer between fuel and air is intensified - mixture formation with a mass transfer coefficient of μ _t , many times higher than molecular μ, which ensures (in the absence of stagnant zones) high homogeneity of the mixture and α≈const - over the entire volume of the combustion chamber.

After ignition spark - 11 μ _m when the highly> μ-phase vapor-air mixture, and a heat exchange coefficient λt >> λ ensures lowering combustion temperature when α> 1,5 - T _c to a value not exceeding T _act NO _x formation reactions and low content of CO, CH and soot.

At the end of the combustion process and the piston-spool opens - 4 exhaust ports - 2, the exhaust starts under exhaust pressure, and after reducing it to the purge pressure, the pressure created by the compressor in front of the valve is 10.

As a result of such a constructive organization of the film-vortex method of mixture formation and combustion, the technical and economic resource-saving and environmental criteria parameters are increased to the best world-class parameters.

Claims (1)

A two-stroke internal combustion engine with electronic control of a wide fractional fractional fuel injection system comprising a cylinder, in the wall of which there are exhaust slots, a fuel nozzle, a spool piston, a plug, a cylinder head, characterized in that it contains a fuel-air channel, located in the cylinder head at an angle β = 75 ÷ 80 ° to the axis of the cylinder and passing into the swirl, the axis of which coincides with the axis of the cylinder, an inlet valve with a bevel angle β ₁ = 10-15 °, installed in the cylinder head so that its axis coincides with the axis of the swirl, while the fuel-supply nozzle is installed in the fuel-air channel parallel to the axis of the cylinder, the candle is installed in the cylinder head, and the outlet-slots are located tangentially at an angle β ₂ = 75 ÷ 80 ° to the cylinder axis and connect the cavity cylinder with an annular cavity of the gas collector.

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