RU2215897C2 - Fuel injection advance angle setting method - Google Patents

Abstract

FIELD: mechanical engineering. SUBSTANCE: invention relates to internal combustion engines, particularly, to methods of setting fuel injection advance angle. According to proposed method taken as injection advance angle is its value at which mean indicated pressure is maximum at preset fuel consumption. Injection advance angle is adjusted to mean indicated pressure within preset range to provide minimum combined index of exhaust gas harmfulness. Analog signals from pressure transmitter and from sensors of gas analyzer pass to inputs of unit calculating combined index of exhaust gas harmfulness and unit calculating mean indicated pressure and further on to comparator unit where control signal is formed which gets to control unit of fuel injection advance angle and to control member of high-pressure fuel pump delivering fuel into combustion chamber through nozzle. In combined index of exhaust gas harmfulness particles of soot, nitrogen oxides, carbon and hydrocarbons are considered. EFFECT: reduced toxicity of exhaust gases at any loads. 2 cl, 1 tbl, 2 dwg

Description

 The invention relates to the field of testing internal combustion engines (ICE), in particular to methods for assessing the technical condition of engines according to their energy, economic and environmental indicators, and can be used, for example, when regulating the fuel equipment of ICE at the points of environmental control of diesel locomotives.

 In engine building, when creating and testing ICEs, there are known methods for determining the optimal lead angles of injection and the duration of fuel supply, at which the maximum average indicator pressure is determined at a given fuel consumption [1]. However, this cannot achieve a reduction in the toxicity of engine emissions; moreover, the search for the optimal angle of fuel start and its correction are not carried out under operating conditions at partial loads [2].

The closest technical solution to the claimed method of adjusting the angle of advance of fuel injection is a method in which the angle of advance of injection φ _{o.pr is} taken to be slightly less than that at which the maximum average pressure is reached at a given fuel consumption, which leads to a significant decrease in the maximum cycle pressure P _z , the rigidity of the process and some reduction in emissions of nitrogen oxides NO _x [1].

However, the known method has several disadvantages. With this method of determining the optimal angle of advance of fuel injection with a relatively small deterioration in indicator indicators, emissions of products of incomplete combustion — hydrocarbons С _n Н _m and carbon dioxide СО, as well as exhaust smoke are noticeably increased. As a result, with an excessive decrease in the angle of advance of the injection, the energy, economic, and environmental performance of the diesel engine substantially deteriorates. In addition, the optimal value of the injection advance angle substantially depends on the operating mode of the heat engine and requires adjustments depending on the actual technical condition of the machine. In idle mode, the relative values of toxic emissions increase, and the initial phase of fuel supply remains the same. It is known that under operating conditions for diesels, the largest gross emissions into the atmosphere are precisely from soot, nitrogen oxides, carbon oxides and hydrocarbons, while these substances have the following aggressiveness factors normalized by CO (A _co = 1): A _PM = 200 .. .300, A _NOx = 41.1 and A _sn = 3.16 depending on the type of fuel [3]. Thus, the known method for determining the optimum angle of advance of the injection φ _o.pr.p. does not take into account the total indicator of the harmfulness of exhaust gases E, which determines the effect of the entire spectrum of harmful substances on the environmental performance of the engine.

 The technical result of the invention is to reduce the toxicity of internal combustion engine emissions over the entire load range through the use of an aggregate indicator of the harmfulness of emissions in the process of adjusting the angle of advance of fuel injection.

 The technical result is achieved by the fact that the method of adjusting the timing of the fuel injection of the internal combustion engine, at which the injection timing is taken to be such a value that the maximum average pressure is reached at a given fuel consumption, characterized in that the value of the timing of the timing of the injection according to the average indicator pressure is adjusted in an acceptable range of regulation so that the total indicator of the harmfulness of exhaust gases is minimal.

 Another difference in the method of controlling the angle of advance of fuel injection is that in the aggregate indicator of the harmfulness of exhaust gases, soot particles, nitrogen oxides, carbon oxides and hydrocarbons are used.

 Figure 1 shows the block diagram of the implementation of the method.

 As follows from figure 1, the analog signals from the pressure sensor 2 in the cylinder of the engine 1 and from the sensors of the gas analyzer 6 installed on the exhaust manifold 5, are fed to the inputs respectively of the calculation unit of the total exhaust gas hazard indicator 7 and the average indicator pressure calculation unit 8. The outputs of the blocks 7 and 8 go to the comparison unit 9, where a control signal is generated, which is fed to the block for adjusting the angle of advance of the fuel injection 10, then to the regulatory body of the high-pressure fuel pump 4, tvlyayuschego feeding fuel into the combustion chamber through the nozzle 3. The functions of blocks 7, 8 and 9 can perform the personal computer. In addition, the specifications of the engine under test and a fuel passport can be entered into the PC. As a result, all critical parameters are calculated, according to which the search of the optimum angle of advance of fuel injection is carried out. Namely, the average pressure and the cumulative indicator of the harmfulness of exhaust gases E at a given fuel consumption. As a result of solving the optimization problem on the computer, the required fuel injection advance angle is automatically determined and adjusted.

Figure 2 presents the calculated graphs of the dependence of the average indicator pressure P _i and the cumulative indicator of the harmfulness of exhaust gases E on the value of the timing of the fuel injection φ _o.vpr for a diesel diesel engine.

A slight increase in the lead angle of the fuel injection leads to a significant decrease in the toxicity of harmful emissions of soot, carbon monoxide and hydrocarbons (according to indicator E) with a slight increase in NO _x emissions, a decrease in the average indicator pressure and an increase in P _z . The shaded area of the graph is the zone of regulation of the angle of advance of fuel injection.

 The table shows the values of the relative changes in the cumulative hazard indicator and the average indicator pressure of the engine.

Change (decrease or increase) in the angle of advance of fuel injection by one degree. p.c. leads to a relative change in the specific gross emission E by 30 - 35%, while the losses in the average indicator pressure P _i do not exceed 0.5%. Indicator E in conventional gr / kg fuel determined from the formula:
E = ΣA _i e _i ,
where A _i is the relative aggressiveness of the substance,
e _i - specific emission of chemical components (g / kg fuel) in the exhaust gases of the engine.

 The proposed method of adjusting the angle of advance of fuel injection can be implemented for any operating conditions of the engine, other than nominal.

 The method is applicable to carburetor engines, especially since in their exhaust gases the highest volumetric content of harmful substances falls on CO (about 6%).

Sources of information
1. Internal combustion engines / Khachiyan A.S. et al. - M.: Higher. school, 1985 .-- 311 p. (prototype).

 2. Astvatsaturov A.E., Bulygin Yu.I. et al. // Computer model of thermogasdynamics and chemical transformations in a piston engine // Izv. universities. North -Cav. region. Tech. Science, 2001. - N 1.

 3. Kutenev V. F., Zvonov G. A., Kornilov G. S. // Standards and quality, 1998. - N 5. - S. 96-101.

Claims (2)

 1. The method of adjusting the timing of the injection timing of the internal combustion engine fuel, at which the angle of timing of the injection is taken to be such a value that the maximum average indicator pressure is reached at a given fuel consumption, characterized in that the value of the angle of timing of the injection according to the average pressure is adjusted in the allowable control range so that the total indicator of the harmfulness of the exhaust gases is minimal, for this the analog signals from the pressure sensor and from the sensors of the gas analyzer they get stuck at the inputs of the unit for calculating the total indicator of harmfulness of exhaust gases and the unit for calculating the average indicator pressure, then for the comparison unit, where a control signal is generated, which is fed to the unit for adjusting the angle of advance of fuel injection, then to the regulating body of the high-pressure fuel pump that delivers fuel into the combustion chamber through the nozzle.  2. The method of controlling the timing of the fuel injection of the engine according to claim 1, characterized in that soot particles, nitrogen oxides, carbon oxides and hydrocarbons are used in the total exhaust gas hazard index.

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