RU2366930C1 - Method for measurement of diesel engine exhaust gases opacity - Google Patents

Abstract

FIELD: physics, measurements.

SUBSTANCE: invention is related to methods of technical diagnostics and may be used for assessment of technical condition of vehicles equipped with diesel engines, by means of exhaust gas opacity control. Video filming of diesel engine exhaust gas flow is carried out at the background near exhaust pipe cut, produced video record is split into serial row of separate pictures (images) according to speed of filming (frame frequency), for every image extent of white background darkening is identified (amount of black soot on white background) and extent of black background lightening (amount of warm grey vapors of oil and other products of incomplete combustion on black background). Produced parametres are reduced to regulated thickness of gas column, for every image total parametre N of "black on white" and "white on black" is identified, and obtained serial row N is used to identify peak (maximum) value of opacity.

EFFECT: improved efficiency of method, possibility to measure opacity in mode of free acceleration and reduced prime cost of realisation.

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Description

The invention relates to methods for technical diagnostics and can be used to assess the technical condition of cars equipped with diesel engines by controlling the smoke of exhaust gases.

A known measurement method based on the transmission of a layer of exhaust gases of a certain thickness and the assessment of light absorption. The requirements for devices that implement this method (and therefore to the method itself) are formulated in Appendix “I” to GOST R 41.24-2003 “Uniform provisions concerning: III Certification of vehicles with compression ignition engines in relation to smoke”.

The disadvantages of this method and devices that implement it are the significant scatter of the measurement results, the complexity and low reliability of the instruments, the effect of ambient temperature and general illumination at the place of measurement on the measurement results.

A known method of measuring the content of soot [Buralev Yu.V. and other device, maintenance and repair of fuel equipment. - M .: 1982, p. 159], based on pumping a fixed volume of exhaust gases through a white paper filter and filtering soot particles from the exhaust gases. It allows you to approximately estimate the smokiness (soot content) of the exhaust gases by comparing the degree of darkening of the initially white filter, on which the soot particles have settled, with standards representing the black scale.

The disadvantage of this method is that it is designed to measure at stationary diesel operation modes and does not allow measurements to be made under free acceleration mode. In addition, it has a significant complexity of measurements, because First, it is necessary to filter the exhaust gases, and then in another functional block measure the degree of blackening of the filter with a photocolorimetric type device.

The objective of the invention is to increase the efficiency of the method, the ability to measure smoke on the free acceleration mode and reduce the cost of implementing the method.

The problem is solved in that in the proposed method for measuring the smoke of diesel exhaust gases, including measuring the degree of change in the background, according to the invention, a screen lined with black and white stripes is used as the background, a video is taken of the diesel exhaust gas flow against the background in the region of the exhaust pipe cut, the video obtained they frame them in a sequential series of individual pictures (images) in accordance with the shooting speed (frame rate), for each image, determine the degree of darker Ia white background (the amount of carbon black on a white background) and the degree of lightening black background (the number of bluish oil vapor and other products of incomplete combustion of fuel on a black background) in the thickness of the analyzed exhaust gas post equal to the diameter of the exhaust outlet, determine the values of parameters N _BW and N _warheads and lead the obtained indicators to the regulated thickness of the gas column, for each i-th image determine the total indicator N _i according to the formula:

N _i = a * N _bb + in * N _bch ,

where N _bw - the component of the smoke "black on white";

N _bch - component of the smokiness "white on black";

a, b - regression coefficients,

from the obtained series N _i , the peak (maximum) smoke value and the maximum integral score of the indicator N _{m are} determined from the set of m consecutive frames received for the regulated time (for example, 0.9-1.1 seconds).

Figure 1 shows the mutual arrangement of the equipment and the diagnosed car, top view, figure 2 shows the relative position of the equipment and the diagnosed car, front view, figure 3 shows a fragment of a sequential series of received frames, figure 4 shows the obtained graph of the formation of the coefficient light attenuation N% in the free acceleration mode of a diesel engine; Fig. 5 shows the obtained graph of the formation of the light absorption coefficient K, m ^-1 in the free acceleration of a diesel engine.

The measurement of exhaust smoke by the proposed method is as follows. Have a set of equipment (screen-background with lined stripes, tripod, video camera) relative to the test vehicle as shown in Fig.1 and Fig.2, that is, with the possibility of video recording of exhaust gas from the exhaust pipe against a black and white screen. They start the engine, turn on the camcorder and implement the free acceleration mode, in accordance with GOST R 52160-2003. The resulting videos are transferred to a personal computer (PC), frame up and receive a sequential series of frames (images), see figure 3. On the received frames, select the scene of the region of cut of the exhaust pipe. Using the program Adobe Photoshop, determine the basic assessment of whiteness (%) of the white strip and blackness (%) of the black strip. Next, on the selected scene, for each frame, the degree of darkening of the white background and the degree of lightening of the black background are determined as the differences between the current values and the basic estimates of the white and black bars, respectively. The values of these estimates N _bb (%) and N _bch (%) obtained at the exhaust gas layer thickness equal to the cut-off diameter of the exhaust pipe lead to a gas column thickness of 0.43 meters, regulated by GOST, as follows. It is known that the light absorption coefficient K and the light attenuation coefficient N are interconnected by a logarithmic dependence:

where L is the thickness of the translucent layer of exhaust gases (effective base of the smoke meter), m;

N - linear scale readings,%;

K is the corresponding value of the absorption coefficient, m ^-1 .

Then, if you make the conversion,

light attenuation coefficient will be equal to:

Find the value of the indicator K over a length L equal to the diameter of the pipe cut (formula 1). Next, substitute the found value of the indicator K and the length L = 0.43 meters in the formula for finding the indicator N (formula 2), thereby bringing the light attenuation coefficient to the set gas column thickness of 0.43 m. The total smokiness N is determined by the equation:

N = a · N _bb + in · N _bch ,

where N _bw - the component of the smoke "black on white",%;

N _bch - component of the smoke “white on black”,%;

a and c are the regression coefficients obtained from experimental data with an exemplary smoke meter.

The considered procedure is applied to each frame of a sequential series and a series of estimates of the current exhaust smoke of a test vehicle is obtained at free acceleration with a frequency corresponding to the video recording speed of 30 frames per second, 60 frames per second, 100 frames per second, etc. depending on the capabilities of the camcorder. From the obtained series of values, the peak (maximum) value of the exhaust smoke is determined for each cycle of diesel free acceleration.

Example

In accordance with the proposed method, a video was taken of the exhaust gas of a diesel engine. The camcorder provided a shooting speed of 60 frames per second. The resulting video was uploaded and processed using Adobe Photoshop. Got a number of estimates of the total smoke (black on white + white on black) of diesel exhaust gases under free acceleration. The data led to a state standardized gas layer thickness of 0.43 meters. The video processing results are presented in the table.

According to the data obtained, graphs are constructed, which are presented in figure 4 and figure 5. From the obtained graphs, the peak (maximum) for the free acceleration cycle was determined for the exhaust smoke. As can be seen from figure 4 in terms of N, it is N = 80.89%, from figure 5 it is seen that in terms of indicator K it is K = 3.849 m ^-1 .

It is also possible to determine the maximum integral score of the N indicator from the totality of consecutive frames obtained in a regulated time (for example, in 0.5 seconds). For the case under consideration, it is N = 47.1%.

Thus, using the proposed method, it is possible to measure the smoke of the exhaust gas of a diesel engine in any mode, including the free acceleration mode.

The proposed method for measuring the smoke of diesel exhaust gas is based on the use of mass-produced household video cameras, which makes it possible to lower the cost of implementing the proposed method. (We do not take into account the cost of the PC, because at any modern point of PC diagnostics, there is always a need and there is no need to purchase it additionally.) It is only necessary to develop and install specialized software on the PC for the automated processing of the resulting video.

In the proposed method, the contact of the exhaust gases with the measuring equipment is excluded, which will ensure the possibility of its long-term operation. Given the constant progress in the production of video cameras, namely the improvement of their sensitivity characteristics, the ability to shoot the process from a considerable distance and reduce the cost of video cameras, the proposed method has significant prospects.

Claims (1)

A method for measuring the smoke of diesel exhaust gases, including measuring the degree of change in background, characterized in that the screen is lined with black and white stripes as a background, a video is taken of the diesel exhaust gas flow in the background in the region of the exhaust pipe cut, the resulting video is shot into a series of separate shots (images) in accordance with the shooting speed (frame rate), for each image, determine the degree of darkening of the white background (the amount of black soot on a white background) and the degree of clarification of the black background (the number of bluish vapors of oil and other products of incomplete combustion of the fuel against a black background) at the thickness of the analyzed exhaust gas column equal to the cut-off diameter of the exhaust pipe, the values of _Nbb and _Nbch are _determined and the obtained values are brought to the regulated thickness of the gas column, for each i-th image, the total indicator N _i is determined by the formula
N _i = a · N _bb + in · N _bch ,
where N _bw - the component of the smoke "black on white";
N _bch - component of the smokiness "white on black";
a, b - regression coefficients,
from the obtained series N _i , the peak (maximum) smoke value is determined, and the maximum integral estimate of the Nm indicator from the set of m consecutive frames obtained for the regulated time.

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