RU2475717C2 - Diagnostics method of internal combustion engine, and diagnostics system for its implementation - Google Patents

Abstract

FIELD: measurement equipment.

SUBSTANCE: diagnostics method of internal combustion engine consists in the fact that a number of the most informative diagnostic parameters is measured on an automobile of a certain make at certain failures; diagnostic parameters are determined, the values of which lie within normative limits specified by the manufacturer, as well as those that exceeded the limits of maximum and minimum normative values, on the basis of which a ternary measurement system is introduced (0, +1 and -1 respectively) for each measured parameter; the value of each parameter (in the introduced measurement system) is multiplied by an arithmetic mean from its limit values; values of the obtained products are summed; an integral index of failures, the numerical value of which corresponds to a certain value, is determined.

EFFECT: detection of certain failures of all systems and sub-systems of the engine, including an electronic engine control system owing to determining integral indices of certain failures and their being introduced to the database of software of the system.

1 tbl, 1 dwg

Description

The invention relates to the field of technical diagnostics, in particular to the diagnosis of internal combustion engines, and can be used to determine the technical condition of the electronic control system and engine elements with distributed fuel injection during their manufacture, maintenance and repair.

A known method for diagnosing an internal combustion engine by continuously measuring time intervals corresponding to rotation of the crankshaft at equal and adjacent angular intervals of a given value per engine cycle with synchronization of the start of measurements with the top dead center of the first cylinder, in the process of processing the measurement results, the dependence of the angular velocity of the crankshaft by the angle of its rotation within the cycle of the engine, which determine the dependence of the angular acceleration by the angle of rotation from the crankshaft within the same limits, after which, in the section corresponding to the first half of the period of change in torque on the expansion stroke of the diagnosed cylinder, the change in angular acceleration is presented in the form of a harmonic with a period equal to the period of change in torque, the phase of this harmonic, which varies depending on compression, compare its value with a reference value and make a conclusion about the technical condition of the engine [1]. The disadvantage of this method is the lack of accuracy in assessing the technical condition of the engine, since the adopted diagnostic parameter allows you to determine the general condition of only the cylinder-piston group as a whole and does not indicate specific malfunctions of the engine systems.

There is also a method of assessing the technical condition of an internal combustion engine by measuring the crankshaft speed, which consists in continuously measuring the time intervals corresponding to the rotation of the crankshaft at adjacent and equal angular intervals of a given value, per engine cycle at any steady-state speed mode with synchronization start of measurement with the same cycle cycle of a specific cylinder, determine the value of the crankshaft speed within each angle of the new interval, the dependence of the rotational speed on the angle of rotation of the crankshaft is obtained, the coefficients of unevenness of rotation of the crankshaft within the cycle of the engine and the period of change in torque are determined and the technical condition of the engine is determined from the results [2]. The disadvantage of this method is also the lack of accuracy in assessing the technical condition of the engine, since the adopted diagnostic parameters make it possible to determine the general condition of the cylinder-piston group, the gas distribution mechanism, and the ignition and power systems for a specific cylinder, but do not indicate specific malfunctions.

The closest in technical essence and the achieved effect to the claimed invention is the universal diagnostic complex selected as a prototype, operating according to the method consisting in measuring at a certain operating mode of the engine and its control system diagnostic parameters (content of unburned hydrocarbons, carbon monoxide, carbon dioxide and oxygen in exhaust gases; excess air coefficient; on-board network voltage; ignition timing; closed loop angle Tob breakdown voltage at the spark plug, the spark burning voltage and time); assessment of the measured parameters for compliance with the standards established by the manufacturer for a working vehicle and available in the database; identifying a set of parameters that do not meet established standards; analysis of possible malfunctions of the engine and engine management system (SUD), leading to deviation of parameters from the norm; the formation of a technological map of repair work according to the manufacturer’s documentation and calculation of the cost of repair [3]. The disadvantage of this method is that as the diagnostic parameters of the electronic engine management system (ECM), only the ignition timing and the closed contact angle of the contacts are taken, not taking into account a number of other important parameters that can more accurately determine the technical condition of the ECM. In addition, this method allows you to identify only a list of subsystems, and not specific faulty elements, which leads to a lengthy procedure for sequentially checking all elements of each subsystem.

The aim of the invention is to identify specific malfunctions of all engine systems and subsystems, including electronic engine control systems by determining the integral indicators of specific malfunctions and including them in the complex software database.

This goal is achieved by the fact that on a car of a certain brand, in addition to the diagnostic parameters indicated in the prototype, the fuel injection time by the nozzle, the mass air flow of the engine, the voltage of the oxygen sensor, the voltage of the knock sensor, the coefficient of correction of the injection time and the discharge in the intake manifold are measured, diagnostic parameters, values which are within the regulatory limits established by the manufacturer, and also went beyond the maximum and minimum regulatory values , on the basis of which a ternary system of measurements (0, +1 and -1) of diagnostic parameters is introduced, the value of each parameter (in the introduced measurement system) is multiplied by the arithmetic mean value of its limiting values, the values of the resulting products are summed up and the integral indicator of malfunctions is determined, the numerical value which, together with the name of the malfunction, is entered into the software database of the complex. Having a database with a number of the maximum possible malfunctions, it is possible to accurately identify a specific malfunction, which significantly reduces the complexity of diagnostic work and their cost. In the absence of the numerical value of the calculated integral indicator of the malfunction in the database, the name of the malfunction is identified during the repair work and added to the database.

The invention is illustrated by drawings. Figure 1 shows a diagram of the translation of the values of the diagnostic parameters in the ternary measurement system; figure 2 - the algorithm of the diagnostic complex.

The claimed method for diagnosing an internal combustion engine is as follows.

On a car of a particular brand with certain malfunctions D ₁ , D ₂ , D ₃ , ..., D _{m, a} number of diagnostic parameters x ₁ , x ₂ , x ₃ , ..., x _n are measured, which most fully characterize the operation of the engine and its systems.

The obtained absolute values of the parameters x ₁ , x ₂ , x ₃ , ..., x _{n are} translated into the ternary measurement system (Fig. 1) as follows.

. Если абсолютное значение параметра х_i соответствует условию x_i<x_imin, то в троичной системе измерений оно обозначается как

. Если же x_i>x_imах, то

. На основании нормативных предельных значений диагностических параметров x_mах и x_min, установленных производителем, подсчитывается среднеарифметическое из предельных значений каждого параметра по формулеIf the measured value of the diagnostic parameter x _i corresponds to the condition x _imax ≥h _i ≥x _imin, i.e. it is inside the allowable limit, then this value in the ternary system of measurements takes a value equal to 0

. If the absolute value of the parameter x _i corresponds to the condition x _i <x _imin , then in the ternary measurement system it is denoted as

. If x _i > x _imax , then

. Based on the standard limit values of the diagnostic parameters x _max and x _min established by the manufacturer, the arithmetic mean of the limit values of each parameter is calculated by the formula

и x_н.cp.i и сложения полученных произведений подсчитывается предлагаемый интегральный показатель неисправностиAfter multiplying the values

and x _n.cp.i and the addition of the resulting works, the proposed integral indicator of malfunction is calculated

,

,

, …,

равны нулю и, как следствие, равен нулю интегральный показатель неисправности. При наличии любой неисправности, вызывающей отклонения параметров x_i за их нормативные пределы, показатель H_D принимает отличающееся для каждой неисправности значение. Вычисленные для каждой неисправности интегральные показатели вместе с именем неисправности вносятся в соответствующую базу данных.If a healthy vehicle is diagnosed, then the values

,

,

, ...,

are equal to zero and, as a result, the integral indicator of malfunction is equal to zero. In the presence of any malfunction causing deviations of the parameters x _i beyond their standard limits, the indicator H _D assumes a different value for each malfunction. The integrated indicators calculated for each fault along with the name of the fault are entered into the corresponding database.

An example of the calculation of integral indicators of malfunctions. We have the values of 12 diagnostic parameters x _i obtained experimentally with 5 malfunctions of VAZ engines with distributed fuel injection (table 1).

We calculate the integral indicators of malfunctions presented in table 1, which also includes the necessary initial data.

where CH is the content of unburned hydrocarbons in the exhaust gas, ppm; WITH - the content of carbon monoxide in the exhaust gas,%; СО ₂ - carbon dioxide content in the exhaust gases,%; O ₂ - oxygen content in the exhaust gas,%; T - injector fuel injection time, ms; Q - mass air flow rate of the engine, kg / h; φ _oz - ignition timing, degrees; U _O2 - voltage of the oxygen sensor, V; U _d.d. - voltage of the knock sensor. AT; k is the injection time correction factor; p - vacuum in the intake manifold, kPa; U _CR - breakdown voltage in the high-voltage circuit of the ignition system, kV.

и x_н.ср.i (таблица 1), по формуле (2) рассчитываем значение интегральных показателей Н_D для каждой из отмеченных в таблице 1 неисправностей.Knowing the values

and x _n.sr.i (Table 1), the formula (2) count value of the integral indices N _D for each of the noted in Table 1 malfunctions.

H _D1 = + 1 × 112-1 × 0.4 + 1 × 14.1-1 × 0.9 + 1 × 4.1-1 × 9.2 + 1 × 11.5-1 × 0.35 + 1 × 0.8-1 × 0.88 + 0 × 58 + 1 × 17 = 147.77

H _D2 = + 1 × 112 + 1 × 0.4-1 × 14.1-1 × 0.9 + 1 × 4.1-1 × 9.2 + 1 × 11.5 + 1 × 0.35 + 0 × 0.8 + 1 × 0.88-1 × 58-1 × 17 = 30.03

H _D3 = + 1 × 112 + 1 × 0.4 + 1 × 14.1-1 × 0.9 + 1 × 4.1 + 1 × 9.2-1 × 11.5 + 1 × 0.35- 1 × 0.8-1 × 0.88 + 1 × 58-1 × 17 = 167.87

H _D4 = + 1 × 112-1 × 0.4 + 1 × 14.1 + 1 × 0.9 + 1 × 4.1-1 × 9.2-1 × 11.5-1 × 0.35 + 1 × 0.8 + 1 × 0.88 + 1 × 58 + 0 × 17 = 168.53

H _D5 = + 1 × 112-1 × 0.4 + 1 × 14.1-1 × 0.9 + 1 × 4.1-1 × 9.2 + 1 × 11.5-1 × 0.35 + 1 × 0.8 + 1 × 0.88 + 1 × 58-1 × 17 = 172.73

As you can see, all calculated integral indicators H _D differ in their numerical values.

This method of diagnosing an internal combustion engine and a diagnostic complex for its implementation can accurately identify specific malfunctions and significantly reduce the complexity of diagnostic work and their cost.

Information sources

1. Patent No. 2187792 RU, MKI, cl. G01M 15/00. A method for diagnosing an internal combustion engine. Publ. 08/20/2002.

2. Patent No. 2037803 RU, MKI, cl. G01M 15/00. A method for assessing the technical condition of an internal combustion engine. Publ. 06/19/1995.

3. Universal diagnostic complex DTS-25. Holding DIAMAX. Internet resource http://mosdialab.ru (prototype).

Claims (1)

A method for diagnosing an internal combustion engine by measuring diagnostic parameters and comparing them with standard values, characterized in that on a particular car brand with certain malfunctions, the fuel injection time by the nozzle, mass air flow of the engine, oxygen sensor voltage, knock sensor voltage, time correction coefficient are additionally measured injection and vacuum in the intake manifold, diagnostic parameters are detected, the values of which are in the normative the limits established by the manufacturer, and also went beyond the maximum and minimum standard values, on the basis of which a ternary measurement system is introduced (0, +1 and -1, respectively) for each measured parameter, the value of each parameter (in the introduced measurement system) is multiplied by the arithmetic mean from its limit values, the values of the resulting works are summed up, the integral indicator of malfunctions is determined, the numerical value of which corresponds to a specific malfunction.

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