RU2548236C1 - Method of technical diagnostic of fine filter of diesel engine fuel system - Google Patents

Abstract

FIELD: machine building.

SUBSTANCE: method means fuel pressure measuring in two points of the diesel engine fuel system, first pressure P_"ТН" is measured at fuel fine filter (F) input, the second pressure P_"ТД" is measured at filter output. Series of at least three measurements is made at various rotation speeds of the diesel engine crankshaft. The measurement results are processed, based on their results filter state is estimated, and scheduled maintenance is planned.

EFFECT: simplified diagnostic of the filter state due to use of the minimum number of transmitters, and reduced labour content due to determination of the filter contamination degree during operation and the scheduled maintenance planning.

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Description

The invention relates to the field of engine engineering, in particular to methods for diagnosing the state of a diesel fine filter.

A known filter control method is that the pressure drop Δp on the filter is measured and when the acceptable pressure drop is reached, it is turned off for washing, a Venturi nozzle is installed in series with the filter, on which the pressure drop Δp _sv is measured, the ratio k = Δp _sv / Δp is determined , compare it with a permissible value of k _extra = Δp _sv / Δp _about , where:

Δp _sv - the measured pressure difference at the venturi nozzle;

Δp is the measured pressure drop across the filter;

Δp _{about the} pressure drop across the filter at the maximum allowable contamination and calibration fluid flow rate V _o ,

and turn off the filter for washing when equality k = k _{extra is} reached, provide k _extra = 1, while the filter is turned off for washing when it reaches the equality of the pressure drops Δp _sv / Δp. (RU patent No. 2282481, class B01D 37/04, 2006)

The disadvantages of the method are:

- there is no methodology for determining the degree of wear and depressurization of the filter, which reduces the technical level of the method;

- the number of measurements determining the filter pressure at various frequencies of rotation of the cranked engine in the zone of the pressure threshold at the inlet and outlet of the filter is not indicated.

A known method for determining the state of a fine filter using the KI 4801 device, in which the pressure drop is determined by the results of pressure measurements in front of the filter and behind the filter, at a fuel pressure behind the filter below the regulated limit, the bypass valve is checked, replacing it with a control valve, if the readings do not change, this indicates the extreme pollution of the filter elements and the need to replace them ("Diagnosis of the diesel power system. Fine filter" website: http: //www.avtoinstrume ntarii.ru/remont/21#more-21)

The disadvantages of the method are:

- the inability to diagnose the state of the filter during engine operation;

- the method allows you to determine only the maximum pollution of the filter and does not allow to determine the degree of contamination of the engine filter in operation and plan scheduled maintenance (flushing, replacement) at the next technical inspection or repair.

A known system for monitoring the state of the filter of an internal combustion engine, adopted as a prototype, contains a filter, a pressure meter (pressure sensors), the cavities of which are communicated by channels with the input and output of the filter and which is included in the engine signal circuit, the system is also equipped with an electronic control unit, temperature sensors coolant and engine speed, while one of the inputs of the electronic control unit is connected to a pressure meter (pressure sensors), and the second and the third inputs of the unit are connected respectively to temperature and speed sensors, one of the outputs of the electronic control unit is connected to the signal elements of the engine signal circuit. When the engine is running on the filter, a pressure drop Δp is created, depending on the fuel consumption through the filter, which is taken into account by the engine speed using the engine speed sensor, and the pressure drop Δp depends on the viscosity of the fuel, which in turn depends on the fuel temperature and is taken into account temperature sensor. The pressure drop Δp for a given speed and temperature conditions of the engine must be in a certain range from Δp _min to Δp _max , the pressure drop Δp is less than the minimum allowable pressure drop Δp min, due to the resistance of the new filter element, indicates the depressurization of the filter element. As a result, unfiltered fuel will start to enter the engine, causing increased abrasive wear of the engine, the electronic unit gives a signal about the depressurization of the filter and gives a signal to stop the engine. An increase in the pressure drop Δp above the maximum allowable Δp _max indicates a clogged filter element, and the electronic unit gives a signal about the need to clean or replace the filter.

(RU patent No. 2252811, class B01D 35/14, B01D 37/04, publ. 2005)

The disadvantages of the method are:

- the complexity of its implementation, because it is required to have dependences of the minimum and maximum pressure drops on the filter in the entire range of operating frequencies of the engine crankshaft and in the entire range of operating temperatures of the coolant;

- the method allows to determine only the maximum pollution of the filter and does not allow to determine the degree of contamination of the filtering element of the engine in operation and to plan routine maintenance (flushing, replacement) at the next technical inspection or repair.

The technical result of the invention is the simplicity of the implementation of the diagnostic method by using a minimum number of sensors and reducing the complexity of maintenance by determining the degree of contamination of the fine filter of the diesel fuel system during operation and planning routine maintenance.

The specified technical result is achieved by the fact that in the method of technical diagnosis of the fine filter of the diesel fuel system, which consists in the fact that pressure sensors continuously measure the fuel pressure at two points of the diesel fuel system, the first pressure P _TN is measured at the inlet to the fuel fine filter , the second pressure P _ТД - at the outlet of the filter, the measurement data are transmitted to the electronic unit, and a series of at least three measurements of the fuel pressure at the inlet to the filter P _ТН and the output e from the filter P _TD at various frequencies of rotation of the crankshaft of a diesel engine, calculate the coefficient k by the formula:

where P _THi is the pressure at the inlet to the fine filter for the i-th measurement,

P _TDi is the pressure at the outlet of the fine filter for the i-th measurement,

n is the number of measurements in the series,

the k coefficient is compared with a k ₀ value corresponding to a clean fuel fine filter, and in the case when the k coefficient is less than the k ₀ value, a filter depressurization message is generated and the degree of pollution is not determined, the k coefficient is compared with a k _max value corresponding to the maximum allowable pollution fine fuel filter, and when the coefficient k is greater than k _max, a message is formed on the limit contamination of the filter and the degree of contamination do not determine if the coefficient k is in the range from k ₀ to k _max, determining the degree of contamination of the filter Z the formula:

and based on the amount of pollution Z they plan to carry out routine maintenance of the fine fuel filter.

Below the present method is illustrated in the drawing.

The method is implemented using a device in which to measure the fuel pressure in the fuel system 1 of a diesel engine 2, a pressure sensor 3 is used, installed after the fuel pump 4 at the inlet of the fuel fine filter 5, at the outlet of the filter 5, a pressure sensor 6 is installed to control the frequency a sensor 7 is installed for rotation of the crankshaft of diesel engine 2, the measured pressure values from the pressure sensors 3, 6 and 7 are transmitted to the electronic unit 8, where the information received from the sensors is processed.

The method is as follows. A method for the technical diagnosis of the filter 5 for fine cleaning the fuel system 1 of diesel 2 is based on a linear dependence of the pressure P _TD at the outlet of the filter 5 on the pressure P _TH at the inlet to the filter 5, which is described by an equation of the form:

where k is the pressure coefficient of the system;

b is a free term of the equation.

The coefficient k does not depend on the viscosity and fuel consumption in the system, but depends only on the total area of passage openings in the fine fuel filter and can be determined by the least squares formula. When the filter 3 fine filter of the fuel system 1 is contaminated, the total area of the through holes in the filter 3 decreases, which leads to an increase in the coefficient k. When depressurization of the filter 3 is an increase in the flow cross sections and a decrease in the coefficient k.

The rotational speed of the diesel engine crankshaft 2, measured by the rotational speed sensor 7, the pressure value P _ТН at the inlet to the fuel filter 5, measured by the sensor 3, and the pressure value P _ТД at the outlet of the filter 5, measured by the sensor 6, are transmitted to the electronic unit 8 , where, provided that the rotation speed changes relative to the previous measurement, the pressures P _THi and P _{TDi are summed} . When the number of measurements n in the series exceeded three, in the electronic unit 8 the calculation of the coefficient k is carried out:

The calculated coefficient k is compared with a value of k ₀ corresponding to a clean fuel fine filter, and in the case when the coefficient k is less than the value of k ₀ , a message about the filter depressurization is generated and the degree of pollution is not determined. Otherwise, the coefficient k is compared with the value of k _max corresponding to the maximum allowable pollution of the fine fuel filter, and in the case when the coefficient k is greater than the value of k _max , a message about the maximum pollution of the filter is generated and the degree of pollution is not determined. If the coefficient k is in the range from k ₀ to k _max , the degree of pollution Z of the filter is determined by the formula:

and based on the amount of pollution Z they plan to carry out routine maintenance of the fine fuel filter.

Claims (1)

The method of technical diagnosis of the fine filter of the diesel fuel system, which consists in the fact that pressure sensors continuously measure the fuel pressure at two points of the diesel fuel system, the first pressure P _ТН is measured at the inlet of the fuel fine filter, the second pressure Р _ТД is at the output from the filter, the measurement data is transmitted to the electronic unit, characterized in that produce a series of at least three measurements of the fuel pressure upstream of the filter F _TH and outlet of the filter F _TH at different frequencies rot scheniya engine crankshaft, the coefficient k is calculated by the formula:
$$k=\frac{n{\displaystyle \sum _{i=\mathrm{one}}^n{P}_{TNi}{P}_{TDi}-{\displaystyle \sum _{i=\mathrm{one}}^n{P}_{TNi}{\displaystyle \sum _{i=\mathrm{one}}^n{P}_{TDi}}}}}{n{\displaystyle \sum _{i=\mathrm{one}}^n{P}_{TDi}^2-{\left({\displaystyle \sum _{i=\mathrm{one}}^n{P}_{TDi}}\right)}^2}}$$

Where
P _THi is the pressure at the inlet to the fine filter for the i-th measurement,
P _TDi is the pressure at the outlet of the fine filter for the i-th measurement,
n is the number of measurements in the series, compare the coefficient k with a value of k ₀ corresponding to a clean filter for fine fuel refinement, and in the case when the coefficient k is less than the value of k ₀ , a message about the depressurization of the filter is generated and the degree of pollution is not determined, compare the coefficient k with the value k _max, corresponding to the maximum allowable contamination fine fuel filter, and when the coefficient k is greater than k _max, a message is formed on the limit contamination of the filter and the degree of contamination do not determine if the factor itsient k is in the range of from k ₀ to k _max, determining the degree of contamination of the filter according to the formula Z:
$$Z=\mathrm{one\; hundred}\times \frac{\left(k-k_0\right)}{k_{\max }-k_0},\%$$

and based on the amount of pollution Z they plan to carry out routine maintenance of the fine fuel filter.