RU2158845C2 - Diesel engine fuel system with injection pump and projectors connected by hp pipes - Google Patents

Abstract

FIELD: mechanical engineering; diesel engine fuel systems. SUBSTANCE: proposed invention can be used in designing new fuel feed systems, particularly in developing methods of fuel-air mixture supply, and devices implementing such methods. System has diesel engine with installed main injectors connected by means of high pressure fuel pipes and T-pipes. Additional injector is installed on air pipe. This injector is hydraulically coupled through high pressure fuel pipe, non-return valve unit, fuel accumulator and control unit with pumping units of high-pressure fuel-injection pump through-pipes. Fuel injection pump is coupled with fuel tank through valve, coarse fuel filter and fuel feed pump, fine fuel filter and fuel heater (heat exchanger) by means of low-pressure fuel pipe and high-pressure fuel pipe. Fuel leaks from main injectors and additional injector return into tank along leak fuel pipes. Spring and piston are installed in fuel accumulator. EFFECT: improved quality of fuel mixing in diesel engine. 3 cl, 2 dwg

Description

 The invention relates to engine building and can be used both when creating new fuel supply systems at engine-building plants, and in various organizations using diesel engines as power plants.

 A known diesel fuel supply system containing cylinder nozzles for injecting fuel into the combustion chamber (cylinder) of the engine, a high pressure fuel pump (TNVD), fuel filters, a low pressure fuel pump (0.2 ... 0.3 MPa), a fuel tank and low and high pressure fuel pipelines ("Fuel equipment of automotive diesel engines": Handbook, - 2nd ed. revised and add. - L.: Mechanical engineering. Leningrad., 1990 - 352 p.).

Each fuel injection pump section delivers a cyclic dose of fuel to one diesel cylinder in accordance with the operating mode of the engine and the operation of its cylinders. In this case, the cyclic fuel supply by the high-pressure pump is performed at the end of the compression stroke for a very "short" period of "time" (20 ... 45 ^o p.c.c.).

 The disadvantage of this system is insufficient mixture formation during operation at low and medium crankshaft speeds, as well as deterioration of mixture formation and fuel combustion at rated load, which reduces the efficiency of the engine, the content of soot particles increases in exhaust gases (exhaust smoke), toxic and carcinogenic substances (oxides of nitrogen, carbon, hydrocarbons, aldehydes, benz (a) pyrene, etc.), the environmental reliability of a diesel engine is low.

 A known system of two-phase (separate) fuel supply of a diesel engine, which is a prototype, which is characterized by the fact that increasing the fuel supply efficiency is achieved by organizing the supply of liquid fuel to the cylinder (s) through the nozzle (s) (I stage), and partly into the inlet (air) valve area by means of annular grooves on the valve guide sleeve and a longitudinal recess on the valve stem.

 The fuel supply system provides during suction (suction stroke) the fuel is supplied to the intake valve through a special jet through drilling in the cylinder head and the low pressure pipe from the fuel priming pump, and then at the end of the compression stroke, the main dose of fuel is fed through the nozzle to the engine cylinder in the usual way . The amount of pre-supplied fuel is determined by the diameter of the nozzle passage and the connection time of the annular grooves with the low-pressure fuel line (AS USSR N 953249, MKI F 02 M 45/00, 1980, prototype).

The disadvantage of this system is the difficulty of dispensing fuel depending on the operating modes of the diesel engine, as well as insufficient spraying of the preliminary part of the fuel supplied to the intake valve, deterioration of the mixture formation due to the ingress of large drops of fuel on the piston bottom and cylinder wall (combustion chamber), which is fraught smoke exhaust due to incomplete burning of fuel at the expansion stroke, but even in this case, for example, on the D-240 engine, the fuel supply system allows to quantitatively reduce ¹ :
- nitrogen oxides - almost 40%;
- carbon oxides - about 20%;
- carbon - by 10%.

 Also known is a diesel fuel supply system according to the USSR patent N 990087, MKI F 02 N 17/04, F 02 17/53, 1978, close to the claimed one (prototype).

 The disadvantage of this system is a decrease in the quality of mixture formation due to the complexity of the fuel supply to the diesel cylinders (a three-way valve is located in the main pipeline, etc.).

An object of the invention is to improve the quality of mixture formation by installing in the second stage of a split fuel supply system (PCT) a fuel battery acting as a damper-damper and a control unit that automatically or forcibly cuts off the fuel supply to V.T. when starting the engine, as well as when the engine is running at low engine speeds (n≤1000 min ^-1 ).

 The objective is achieved in that the diesel fuel supply system containing a high pressure fuel pump, high pressure fuel lines, main nozzles installed in the cylinders, an additional nozzle (Tareev S.V., Vladimirov N.A. “Reducing the toxicity of exhaust gases of VTZ engines with a two-phase method of fuel supply to the engine cylinder. "Abstracts of the scientific and technical seminar SIMSH. Issue 1, Saratov, publishing house of SSU, 1989, pp. 15-16), installed on the inlet pipe (manifold), according to the invention is equipped with a block of return apanov, fuel battery and control unit.

 In addition, the control unit is made in the form of an electromagnetic or electro-hydraulic valve.

 In addition, a spring and a piston are installed in the fuel accumulator.

 In FIG. 1 is a schematic diagram of a “Diesel split fuel supply system” using the D-240 diesel as an example. In FIG. 2 shows a schematic diagram of a fuel accumulator.

 On diesel 1, the main nozzles 2 are installed (numbers N 1 ... N 4 in one row), connected by means of a high pressure fuel line 3, a tee (adapter) 4, with sections of a high pressure fuel pump 5.

 An additional nozzle 7 is installed on the air pipe 6, which in turn is hydraulically connected by a high pressure fuel pipe 8, a check valve block 9, a fuel accumulator 10 and a control unit 11 with sections of a high pressure fuel pump (TNVD) (via tees 4).

 The high-pressure fuel pump is connected to the fuel tank 12, which contains fuel, a valve 13, a coarse fuel filter 14, a fuel priming pump 15, a fine fuel filter 16 and a fuel heater (heat exchanger) 17, using a low pressure fuel pipe 18 and a high pressure fuel pipe 19. Excess fuel from nozzles 2 and nozzles 7 flows, respectively, through pipelines 20 and 21 to tank 12.

 In the fuel accumulator 10, a spring 22 and a piston 23 are installed.

 A split fuel supply system of a diesel engine operates as follows.

Fuel from the fuel tank 12 is supplied by the fuel pump 15 through filters 14 and 16 with the valve 13 open (at an ambient temperature below +5 ^° C, the fuel can be heated using a heater 17 installed in one of the mains of the fuel supply system) in the high-pressure fuel pump 5.

 In accordance with the order of operation of the engine cylinders (1-3-4-2), the fuel injection pump sections (I ... IV) supply a fuel flow through the high pressure pipe 3, which after the tees 4 flows to the corresponding main nozzles with numbers N 1 ... N 4 (I stage) and through high pressure pipelines 8 to an additional nozzle 7 installed on the air pipe 6 (II stage).

 In the line of high pressure fuel pipelines 8 supplying fuel to the additional nozzle 7, a check valve block 9, a fuel accumulator 10, a control unit 11 are installed.

 The fuel flow from the injection pump sections 5, the check valve block 9 through high pressure pipes enters the fuel accumulator 10 and, interacting with the piston 23, compresses the spring 22.

 The spring 22, in turn, acts on the piston 23 and thereby the fluctuations in the pressure of the fuel supplied by each section of the injection pump to the nozzles 2 and 7 are reduced.

The control unit 11, which is an electromagnetic valve, is connected by an electric circuit to a sensor mounted on the flywheel of the crankshaft of the engine. When the engine speed of the crankshaft is n≤1000 min ^{-1, the} electric signal from the sensor installed on the flywheel is sent to the electromagnetic valve and the high-pressure fuel line 8 is shut off, the fuel supply through the nozzle 7 to the air pipe 6 is stopped.

The fuel accumulator makes it possible to obtain a uniform fuel supply from the injection pump sections to the additional nozzle 7, which ensures high-quality atomization of fuel in the air pipeline, increasing the economic and environmental performance of the engine. The control unit 11 allows you to perform both automatic at n≤1000 min ^-1 , and forced shutdown (inclusion) of the second stage, which allows to improve the economic performance of the claimed system.

The first part of the cyclic dose of fuel preliminarily fed into the pipeline 5 by an additional nozzle 7 at the suction stroke is sprayed into small droplets, evaporates and intensively mixed with air at the suction and compression strokes, which improves the uniformity (homogeneity) of the air-fuel mixture (premature self-ignition is not allowed from due to the large coefficient of excess air α = 3 ... 10). The second part of the cyclic dose is injected into the well-prepared air-fuel mixture with the help of cylinder nozzles at an injection advance angle of Θ _forward . In this case, complete combustion of the fuel occurs without a significant emission of soot from the exhaust gases, as well as toxic and carcinogenic substances.

 An example of the implementation of the "split fuel supply".

As the initial data for the calculation, we accept the following:
engine type - four-stroke four-cylinder in-line diesel with the order of operation of the cylinders 1-3-4-2;
diesel fuel in accordance with GOST 305-82;
nominal diesel power N _en = 55.2 kW;
rated speed n _n = 2100 min ^-1 ;
compression ratio ε = 16; the tact factor τ _dv = 4; the total coefficient of excess air α = 1.7;
specific effective fuel consumption g _e = (220 ... 280) g / kWh; fuel density ρ _t = 0.842 g / cm ³ .

= 320•16^1.37-1 = 892 K.Temperature at end of compression stroke
T _c = T _a •

= 320 • 16 ^1.37-1 = 892 K.

At the same time fuel consumption
G _T = N _e g _e = 55.2 (220 ... 280) / 10 ³ = 15.3 kg / h.

где α_ц - коэффициент избытка воздуха в цилиндре

При этом соотношение топлива, впрыскиваемого в цилиндр (G_тц) и во впускной трубопровод (G_твт), составляет

.From the condition T _c = 892 K, we take the value of the coefficient of excess air in the inlet pipe α _w = 5, at which the ignition temperature (self-ignition) of diesel fuel T _{s is} less than T _s , i.e. T _s <T _s Then, for a given general α = 1.7, we can find α _c .

where α _C is the coefficient of excess air in the cylinder

In this case, the ratio of fuel injected into the cylinder (G _TC ) and into the inlet pipe (G _TW ) is

.

Общая цикловая подача топлива:

где i - число цилиндров.Thus, a smaller amount of fuel is injected into the intake pipe or of the total (G _t = 15.3) this proportion will be:

Total Cycle Fuel Supply:

where i is the number of cylinders.

.

.

We accept ΔV _C = 72 mm ³ .

From this fuel stream, it is injected into the intake pipe
ΔV _color = 72 / 2.94 = 24.5 mm ³ .

Injected into the cylinder
ΔV _CC = 72-24.5 = 47.5 mm ³ .

The use of a divided fuel supply according to the proposed method will allow, with a relatively small and uncomplicated refinement of the fuel equipment, to significantly improve the processes of mixture formation and combustion, resulting in reduced exhaust toxicity and emission of soot particles (soot) adhering to carcinogens (benz (a) pyrene, etc. ), on the:
- nitrogen oxides - 60 ... 80%;
- soot - 10 ... 50%.

 Due to the above, an environmental effect is achieved. The most significant is the decrease in the concentration of nitrogen oxides in the exhaust gas during the operation of mobile agricultural equipment working in direct contact with people and animals.

Claims (3)

1. A diesel fuel supply system comprising a high pressure fuel pump, high pressure fuel lines, main nozzles installed in cylinders, an additional nozzle mounted on an air (intake) pipe (manifold), connected to a high pressure fuel pump through a check valve block, characterized in that in the second stage of the divided fuel supply system a fuel accumulator is installed, which acts as a damper-damper, and the control unit automatically or manually, turning off the feed opliva into the air duct when the engine is started and when the engine is running at low speeds of the engine crankshaft (n ≤ 1000 min ^-1).  2. The diesel fuel supply system according to claim 1, characterized in that the control unit is made in the form of an electromagnetic valve.  3. The diesel fuel supply system according to claim 1, characterized in that a spring and a piston are installed in the fuel accumulator.

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