RU2458330C1 - Method of diagnosing ice valve timing gear - Google Patents

Abstract

FIELD: engines and pumps.

SUBSTANCE: invention relates to testing ICE valve timing gear. Proposed method comprises decompressing engine cylinders, cranking engine crankshaft, registering crankshaft angular speed variation, defining amplitudes and phases of crankshaft angular acceleration extremums. Deviation from the latter is used to decide on the state of valve timing gear. Crankshaft is cranked in idling at preset rpm. Cranking is carried by one operating cylinder with other cylinders being decompressed. Angular speed variation is registered within complete kinematic cycle for periods corresponding to expansion strokes in decompressed cylinders.

EFFECT: ruled out extra errors in measurements.

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Description

The invention relates to engine building, in particular to methods for testing and diagnosing an internal combustion engine, and can be used to determine the technical condition of the gas distribution mechanism during manufacturing, operation, maintenance and repair of an internal combustion engine.

Known vibroacoustic methods for diagnosing the gas distribution mechanism of an internal combustion engine by determining the values of the amplitudes of vibration pulses and phase shifts by the angle of rotation of the crankshaft relative to the positions of the top dead points of the pistons of the cylinders. Vibroacoustic pulses are recorded at the moments of landing of the intake and exhaust valves when the engine is running at a steady high-speed idle mode [1] or when the engine speed changes from 800 ... 1000 min ^-1 to maximum revolutions [2]. Comparing the obtained values of the diagnostic parameters with their nominal values, a conclusion is drawn about the technical condition of the gas distribution mechanism, mainly, the thermal clearance of the “valve stem - rocker” interface.

The disadvantages of the vibro-acoustic method are low accuracy and not the universality of the use of diagnostic tools, which implements it, for the whole variety of ICE designs. When diagnosing the gas distribution mechanism by this method, serious difficulties arise with determining the place and method of installing the vibration sensor. The signals coming from individual valves pass to the sensor in a different way and through different media in the engine housing, so their energy will be different, which makes it difficult to decrypt the information received and reduces the accuracy of diagnosis. Due to the significant spread in the frequencies of natural vibrations of the main elements in various engine models, it is almost impossible to create a universal device for diagnosing the gas distribution mechanism using a vibroacoustic method. The use of a number of specialized diagnostic tools for each engine modification is economically and technically unjustified.

There are also methods for diagnosing the gas distribution mechanism, based on measuring the linear displacement of its various elements using magnetoelectric converters [3].

Their main disadvantage is that the material of the valve covers must be made of non-magnetic materials (aluminum alloys or plastics) and preferably transparent, since the installation of the sensors should be strictly oriented with respect to positions, for example, the rocker arm of the valve mechanism. The accuracy of diagnosis by these methods is insufficient due to a violation of the alignment of the installed sensor relative to the element being monitored, which changes as the timing mechanism wears out during engine operation.

The closest in technical essence and the achieved effect to the claimed method is the method of diagnosing valve springs of the gas distribution mechanism of an internal combustion engine selected as a prototype by evaluating their stiffness at a given speed, which consists in the fact that the engine is decompressed, scrolled from an external drive at a given speed , record the change in the angular velocity of the camshaft (crankshaft) within the full kinematic cycle, and v springs evaluated by the change of amplitudes and phases of the extrema of the angular velocity [4].

For the values of the phases of the extrema of the angular velocity, we take the intervals of the crankshaft rotation angle from the positions corresponding to the location of the piston of a particular cylinder at top dead center (TDC) to the positions corresponding to the minimum or maximum angular velocities of the crankshaft determined in the areas of its change during a full cycle expansion in this cylinder.

The disadvantages of this method of diagnosis are narrow specialization aimed at determining the technical condition of only valve springs, and lack of accuracy. The low accuracy of the method is due to the following reasons. Due to the presence of the operation of scrolling the crankshaft of the decompressed engine by the starter due to the dynamic interaction (collisions) of the teeth of the driving gear of the starter with the flywheel crown, the diagram of changes in the angular velocity of the crankshaft by the angle of rotation obtained by the electronic tachometer is a chain of high-frequency peak-like oscillations of the angular velocity relative to their actual values . The superposition of the high-frequency component on the low-frequency component of the change in the angular velocity of the crankshaft distorts the real law of its change. During engine operation, the technical condition of the “starter - flywheel crown” gearing is constantly deteriorating, therefore, the error in determining the values of the amplitudes and phases of the extrema of the angular velocity will also increase with increasing engine life. Experimental data indicate that in the engine scrolling modes, even with permissible gear wear, the individual sequential values of the instantaneous angular velocities of the crankshaft along the angle of rotation in some sections of its change have an oscillation amplitude that contradicts the physical meaning. Existing mathematical algorithms for smoothing the obtained dependences of the instantaneous angular velocities (accelerations) of the crankshaft on the angle of rotation using the methods of moving medians, least squares [5], and their other analogues do not allow satisfactory accuracy in determining the values of the amplitudes and phases of the extrema of the angular velocity of the crankshaft. An additional difficulty in creating algorithms for accounting and reducing the influence of errors on the high-frequency component of the angular velocity is introduced by the unsystematic nature of the change in the clearances in the gear teeth of the starter gear and the flywheel, since their gear ratio is selected so that repeated interaction of the same teeth in the gear is as low as possible (not less than 100 revolutions of the crankshaft). The combination of these causes leads to a decrease in the accuracy and reliability of the known method of diagnosis.

The task of the invention is to improve the accuracy of diagnosing the technical condition of the gas distribution mechanism of an internal combustion engine by eliminating the operation of scrolling the crankshaft of the engine by an external drive device (starter).

The problem is solved in that in the method for diagnosing the gas distribution mechanism of an internal combustion engine, namely, that the engine cylinders are decompressed, the crankshaft is scrolled at a given speed, the change in the angular velocity of the crankshaft is recorded within the full kinematic cycle, according to the proposed technical solution, the crankshaft scroll shaft is carried out when the engine is idling on one cylinder with decompressed others, according to changes the angular velocity, determine the dependence of the angular acceleration of the crankshaft on the angle of rotation for periods corresponding to the expansion strokes in the decompressed cylinders, determine the values of the amplitudes and phases of the extrema of the angular accelerations of the crankshaft in these periods and make a conclusion about the technical state of the gas distribution mechanism .

The difference between this technical solution and the prototype is that, to maximize the consideration of all factors affecting the accuracy of determining the technical condition of the gas distribution mechanism of an internal combustion engine, the values of the angular velocity and acceleration of the crankshaft when it is scrolled are determined without errors introduced by the dynamic interaction of an external drive device - starter - with a gear ring of a flywheel of the engine. As a result of the natural rotation of the crankshaft due to the stored kinetic energy from the operation of the internal combustion engine on one cylinder, the measured values of the instantaneous angular velocities of the crankshaft in the angle of its rotation are most consistent with their real values. Consequently, the values of the amplitudes and phases of the extrema of the angular acceleration of the crankshaft determined by them at the studied intervals, their changes will be more accurate and independent of the technical condition of the gearing “starter - flywheel crown”.

The combination of these features allows you to achieve the necessary technical result, which consists in increasing the accuracy of determining the technical condition of the engine timing mechanism.

The essence of the invention is illustrated by graphs, where figure 1 shows the dependence of the in-cycle angular velocity ω of the crankshaft on the angle of rotation φ when the engine is 4 × 9.2 / 9.2 on one, the first (I) cylinder in order of operation, with decompressed other cylinders (II, IV and III) in idle mode with an average angular velocity ϖ = 50.7 rad / s; figure 2 shows the dependence of the angular acceleration ε of the crankshaft on the angle of rotation φ in the angular interval π ... 2π, corresponding to the dependence ω = f (φ) when implementing the expansion stroke in the decompressed II cylinder (figure 1); figure 3 - dependence of the angular acceleration ε of the crankshaft on the angle of rotation φ in the angular interval 2π ... 3π, corresponding to the dependence ω = f (φ) when implementing the expansion stroke in the decompressed IV cylinder (figure 1):

I, II, IV and III - angular intervals of rotation of the crankshaft corresponding to the expansion strokes in the first, second, fourth and third cylinders (in the order of their work);

1, 2 - respectively, the dependence ε = f (φ) according to experimental data and approximating them by the least squares method;

A _εII , A _εIV are the values of the amplitudes of the angular acceleration of the crankshaft within the angular intervals corresponding to the expansion strokes in the second and fourth decompressed engine cylinders;

φ _εIImax , φ _εIVmax - phase values of the extrema of the maximum values of the angular acceleration of the crankshaft in the angular intervals corresponding to the expansion strokes in the second and fourth decompressed engine cylinders;

φ _εIImin , φ _εIVmin - phase values of the extrema of the minimum values of the angular acceleration of the crankshaft in the same angular intervals.

The proposed method is based on the following theoretical premises.

The operation of the internal combustion engine on the same cylinder as the other cylinders decompressed in idle is traditionally characterized by some average values of the rotational speed, indicator moment and the moment of mechanical losses, which are related to its operation cycle. Moreover, the indicator moment M _i from the operation of one cylinder is completely spent on overcoming the moment M _{mech of} mechanical losses in the moving elements of the engine within the cycle of its operation, that is, M _i = M _mech . In the intervals of the angle of rotation of the crankshaft π ... 2π, 2π ... 3π and 3π ... 4π (Fig. 1), corresponding to the expansion strokes in the decompressed second, fourth and third cylinders (in the order of their operation), the crankshaft performs a “run out”. The change (decrease) in the angular velocity of the crankshaft by the angle of rotation during the “run-out” process is carried out due to the consumption of the stored kinetic energy of the rotating and reciprocating moving engine masses to overcome its internal mechanical losses. Since in reality the mechanical moment M _mehφ motor loss by angle φ of rotation of the crankshaft within the expansion stroke of each cylinder is variable, and the angular velocity of the crankshaft varies depending on nonlinear. The relationship of the moment M _{mech φ of} mechanical losses of the engine with the angular velocity from the crankshaft according to the angle of rotation is determined by the dynamics equation of the internal combustion engine in accordance with the d'Alembert principle [6, p.113-115]

where J is the value of the moment of inertia of the rotating and reciprocating moving masses of the engine, reduced to the axis of the crankshaft;

ε is the angular acceleration of the crankshaft.

- определяет переменную по углу φ поворота коленчатого вала составляющую момента М_Пφ инерционных сил от возвратно-поступательно движущихся масс поршней и части массы шатунов, отнесенных к осям поршневых пальцев соответствующих цилиндров.Depending on (1), the polynomial

- determines the component of the moment M _{Пφ of} inertial forces from the reciprocating moving masses of the pistons and part of the mass of the connecting rods assigned to the axes of the piston fingers of the respective cylinders with respect to the angle φ of rotation of the crankshaft.

The instantaneous value of the moment of mechanical losses M _mech φ in the angle φ of rotation of the crankshaft in the _coast areas corresponding to the periods of the expansion stroke in decompressed II and IV cylinders (Fig. 1) is determined by the following components

where M _MGRφ is the moment spent on the timing mechanism drive;

M _{CPG φ} is the moment from the friction forces in the cylinder-piston group (CPG);

M _Tφ is the moment from the action of friction in the bearings of the crankshaft and the drives of auxiliary mechanisms;

M _Pφ - the moment from the reciprocating moving masses of the engine.

The absence in dependence (2) of the total value of the moment M mechanical _{φ of} mechanical losses of the components of mechanical losses from the action of compression forces and pump losses significantly increase the specific gravity of the mechanical losses M _{MGR φ} spent on the timing mechanism drive, which allows the use of indicators of its change in the angle of rotation of the crankshaft in as diagnostic. The analytical and experimental results of the study of many models of automotive engines (Volzhsky Automobile, Zavolzhsky Motor, Altai Motor and Vladimir Tractor Plants) confirmed the possibility of using the amplitudes and phase shifts of the extreme values of the total moment M mechanical _φ mechanical losses as diagnostic in determining the technical state of the gas distribution mechanism, first of all, four-cylinder four-stroke internal combustion engines, in which the period changes in the total moment M _{mech φ} is equal to π and corresponds to the period of the expansion stroke in the cylinders.

A 4 × 9.2 / 9.2 analysis of the absolute values and intra-cycle changes of the individual components of the total moment M mechanical _{φ of} mechanical losses, performed on the example of a gasoline four-cylinder engine of the Zavolzhsky Engine Plant (ZMZ), in accordance with dependence (2) for the mode of small values of the angular speed of crankshaft shaft (ϖ = 40 ... 70 rad / s) in the angular periods corresponding to the implementation of the expansion stroke in decompressed II and IV cylinders (figure 1), showed:

the proportion of the variable moment in the total moment J of inertia of the engine is 1 ... 2.7%. The numerical value of the variable moment from the inertia forces of the reciprocating moving parts of a four-stroke 4-cylinder in-line ICE

where m is the mass of the reciprocating moving parts;

R is the radius of the crank;

λ = R / l is the ratio of the radius of the crank to the length of the connecting rod.

For the ZMZ engine 4 × 9.2 / 9.2, the moment M _Пφ from the reciprocating moving masses along the angle φ of rotation of the crankshaft varies within insignificant limits - from 0 to ± 5 N · m in a sinusoidal manner. During the operation of the internal combustion engine, the maximum and minimum values of the moment M _Пφ and their phase positions with respect to the crankshaft rotation angle relative to the top dead center points (TDC correspond to angles φ equal to 0, π (180 °), 2π (360 °), 3π (540 °) , see figure 1 ... 3) remain unchanged, since the wear of the conjugation of the reciprocating moving masses is negligible;

the moment M _Тφ from the action of friction in the bearings of the crankshaft and on the drive of auxiliary engines and ICE systems (≈25% of M _mechφ ) is considered to be almost constant in the angle of rotation of the crankshaft, which does not affect the intra-cycle changes in the oscillation amplitudes of the total moment M _mechφ , mechanical losses and phase positions of its extremes;

the variable value of M _{CPG φ} from the friction forces in the _mates of the cylinder-piston group has a characteristic regularity, the peculiarity of which is a constant, independent of the technical condition of the CPG, phase position of extreme values in the angle φ of rotation of the crankshaft. The variable component of the moment M _{CPG φ} varies from 0 to 10 N · m with a period equal to the period of change in torque - π. The magnitude of the value of M _{CPG φ} reaches at φ≈0.45π relative to the positions of the crankshaft, at which the pistons in the cylinders are located in the _upper dead center, M _{CPG φ} = 0 at the positions of the crankshaft corresponding to the pistons in the TDC (BDC) of the cylinders. These periodic fluctuations in the moment M of the _{CPG φ} are reflected in the change in the total moment of mechanical losses M _mechφ , but they are identical with respect to the TDC of the pistons of all cylinders, both in the amplitude of the oscillations and in the phase positions of their extrema. It has been established that during the operation of ICE, due to changes in the technical condition of _{CPG mates} , the amplitude of the oscillations of the moment M _{CPG φ} and, accordingly, the total moment of mechanical losses M _mechφ within the period of change in torque may slightly decrease. According to experimental data, when cranking the crankshaft in the range of angular speeds ϖ = 40 ... 70 rad / s of the decompressed ZMZ 4 × 9.2 / 9.2 engine with extremely worn _CPG elements, the values of the amplitude of the oscillations of the moment M _{mechφ of} mechanical losses in periods corresponding to the cycle expansions in decompressed cylinders decreased by 5 ... 7% relative to their nominal values, however, the values of the phase positions of the extrema of the moment M _mechφ remained unchanged;

the magnitude of the normal forces on the profile of each cam of the engine’s camshaft ZMZ 4 × 9.2 / 9.2 from the action of the elastic forces of the valve springs (excluding friction forces) depending on the angle φ of rotation of the crankshaft is 400 ... 1015 N, and the value of the torque M _{MGR φ} spent on the timing mechanism drive periodically varies from -7 to +7 N · m (when the valve is opened, energy is consumed, and when closed, it is returned). In multi-cylinder internal combustion engines, in each angular period corresponding to the implementation of the expansion stroke in any cylinder with the valves closed, the inlet and outlet valves belonging to other cylinders are opened simultaneously. For example, in the angular interval π ... 2π of the crankshaft rotation during the expansion stroke in the decompressed II cylinder (Fig. 1), the exhaust valve I of the cylinder and the intake valve of the III cylinder are opened. For this reason, the current value of the moment M _{MGR φ} is determined by the sum of the running moments on the _{cam cam} from the links of the valve mechanism of the respective cylinders. In the ZMZ engine 4 × 9.2 / 9.2 from the action of the total _rolling moment M _MGRφ on the camshaft cams, taking into account the friction forces in the cam couples, a difference in the total moment M mechanical _{φ of} mechanical losses exceeding 28 N · m occurs on the crankshaft. For comparison, we point out that according to US data in six-cylinder engines of the same dimension, changes in the moment M _mechφ from the action of the incident moment M _MGRφ on the camshaft cams reach 70 N · m [7, Fig. 1].

The above analytical and experimental data allow us to draw the following conclusions:

the absolute values of the moment M _{MGR φ} spent on the drive of the gas distribution mechanism, in comparison with other components M _Pφ , M _Tφ and M _CPGφ 65 ... 70% determine the total instantaneous value of mechanical losses, forming the amplitude of the variable moment M mechanical _φ mechanical losses on the crankshaft of the decompressed engine when it scrolls, and 100% - phase shifts of the extrema of the moment M _mechφ ;

taking into account that 90% of mechanical losses from the value of the moment M _{MGR φ are} due to losses from the action of friction forces in cam pairs [7, p.13], then the rates of change in the moment M mechanical _{φ of} mechanical losses of the engine along the angle of rotation of the crankshaft corresponding to the period of the expansion stroke in a decompressed cylinder, the cam wear values of individual parts of the gas distribution mechanism — pairs of intake and exhaust valves operating in these intervals of the crankshaft rotation angle — are characterized. Since according to statistics it is known that during operation of an internal combustion engine, one or two camshaft cams reaches their maximum wear limit, when diagnosing a gas distribution mechanism in the case of determining an unacceptable change in the amplitude of oscillations of the moment M _mechφ and phase shifts of its extrema in individual periods of the crankshaft rotation angle, corresponding to the implementation of the expansion stroke in a particular decompressed cylinder, make a conclusion about the inoperability of the links of the gas distribution mechanism richinam wear of the cams of the camshaft, the enlarged thermal gap between the valve tappets and the rocker arm, loss of stiffness valve springs;

changes if the diagram total moment M _mehφ mechanical losses of crank angle for the kinematic loop has a characteristic feature manifestations - the same values for the increment phase shift relative extrema their nominal values during all periods of change, the conclusion is drawn about the mechanism of disturbed phases valve. During operation, a change in the gas distribution phases is possible for reasons of broken kinematic relationships in the elements of the camshaft drive mechanism, errors in the manufacture of its parts during production, or due to an unqualified routine repair of the internal combustion engine. In this case, the position of the camshaft is shifted by a certain angle, the value of which is the same for all its cams. The state of the gas distribution phases according to the diagnostic results is carried out according to the measured values of the increments of the angular intervals Δφ of the phase shifts of the extrema relative to their normative values in each period of change M _mechφ corresponding to the implementation of the expansion stroke in the decompressed ICE cylinders.

Thus, it is proved that the deviation of the technical state elements timing indicators from normative their values when scrolling engine crankshaft to decompress cylinder leads to adequate change quantities amplitudes A _Mmehφ and phase shifts φ _Mmehφ extreme values in the diagram of the moment M _mehφ mechanical losses in the ranges the angle of rotation of the crankshaft related to faulty valve links of the gas distribution mechanism.

However, the direct measurement of the instantaneous values of the moment M _{mechφ of} mechanical losses of the internal combustion engine by the angle of rotation of the crankshaft by operational methods is difficult. Considering that with the engine running at idle on one cylinder with decompressed other cylinders change in moment M _mehφ mechanical losses of crank angle operatively interconnected with intracyclic changes in angular velocity and acceleration relation (2), in practice the method of diagnosing the timing more conveniently and more accurately implemented using electronic means of measuring the angular velocity of the crankshaft with high accuracy, noise immunity and efficiency.

- переменный момент от возвратно-поступательно движущихся масс ДВС при малых частотах вращения коленчатого вала составляет незначительную величину относительно первого, независимого от угла поворота φ, то функциональная связь между моментом М_мехφ механических потерь и ускорением ε_φ по углу поворота коленчатого вала представляется линейной зависимостьюSince in formula (2) the second polynomial

- the variable moment from the reciprocating moving masses of the internal combustion engine at low frequencies of rotation of the crankshaft is insignificant with respect to the first one independent of the angle of rotation φ, then the functional relationship between the moment M of mechanical losses _φφ and the acceleration ε _φ of the angle of rotation of the crankshaft is a linear dependence

Type of relation (4) means that the technical state of the timing adequately moment M _mehφ mechanical loss can be judged in terms of the amplitudes and phases of the extrema ε _φ angular acceleration of the crankshaft at successive angular intervals of rotation of its corresponding decompressed in the expansion stroke cylinder.

Diagnosing the gas distribution mechanism of an internal combustion engine by the proposed method is carried out in the following sequence (for example, a four-cylinder four-stroke engine ZMZ 4 × 9.2 / 9.2).

The engine is heated to a temperature of T = 320 ... 360K coolant and engine oil. A photoelectric sensor BE-178A of the device for measuring the unevenness of the angular velocity of the crankshaft, made, for example, according to A.S., is connected to the crankshaft. USSR №832480, allowing continuous measurement of its instantaneous angular velocity through adjacent angular intervals of 0.5 ... 1 ⁰ within kinematic engine cycle (two revolutions of the crankshaft or camshaft rotation). The start of measuring the instantaneous values of the angular velocity of the crankshaft by the angle of rotation is synchronized with the position of the piston at top dead center - the beginning of the expansion stroke in the I cylinder. Measurements are synchronized by the corresponding orientation of the BE-178A sensor relative to the position of the engine crankshaft and by connecting the inductive sensor of the device to the high-voltage wire of the spark plug of cylinder I. The engine cylinders, except the first, are decompressed by twisting the spark plugs.

The engine is started and the minimum crankshaft speed set for a specific engine model is set (for ZMZ 4 × 9.2 / 9.2, the standard value of the minimum angular velocity is ϖ _NOM = 53 ± 3 rad / s; in Fig. 1, the average angular speed of the crankshaft ϖ = 50.7 rad / s) and record the change in the angular velocity of the crankshaft by the angle of rotation within the full kinematic cycle of the engine. According to the obtained dependence ω = f (φ) (Fig. 1), the dependences of the angular acceleration of the crankshaft on the angle of rotation in the angular intervals π ... 2π (Fig. 2) and 2π ... 3π (Fig. 3) corresponding to the sequential implementation of the expansion cycles are determined in decompressed cylinders II and IV. According to the dependences of the angular acceleration of the crankshaft on the angle of rotation in the indicated periods, the corresponding values of the amplitudes A _εII (Fig.2), A _εIV ( _Fig.3 ) and the phases of the extrema φ _εIImax , φ _εIImin (Fig.2), φ _εIVmax , φ _εIVmin (figure 3) of criminal acceleration, which are compared with their reference values. According to the results of the comparison, a conclusion is drawn about the technical condition of the links of the gas distribution mechanism, which work during periods π ... 2π, 2π ... 3π (Fig. 1) of crankshaft rotation, in which expansion strokes are carried out in decompressed II and IV cylinders.

Shown in figure 2 and figure 3, the dependence of the change in the angular acceleration of the crankshaft, corresponding to the implementation of the expansion strokes in decompressed II and IV cylinders, are characterized by the following diagnostic parameters:

amplitude of extrema in absolute value

A _εII = ε _IImax -ε _IImin = 218.0 rad / s ² , A _εIV = E _IVmax -ε _IVmin = 179.5 rad / s ² ;

phase positions of the minimum values of angular accelerations

φ _εIImin = 64.5 °, φ _εIVmin = 56.5 °;

phase positions of the maximum values of angular accelerations

φ _εIImax = 162.5 °, φ _εIVmax = 161.5 °.

For ZMZ 4 × 9.2 / 9.2 engines, the normative values of the diagnostic parameters are:

in amplitude A _εnom 205 ± 15 rad / s ² ;

according to the phase position of the minimum value of angular acceleration

φ _{εmin nom} = 64.0 ± 2.0 °;

by phase position of the maximum value of angular acceleration

φ _{εmax nom} = 162.0 ± 2.0 °.

The results of comparing the numerical values of the diagnostic parameters obtained during the experiment with their normative values allow us to draw the following conclusion about the technical condition of the elements of the gas distribution mechanism:

the values of the amplitude A _εII = 218.0 rad / s ² and the phases of the angular acceleration extrema φ _εIImin = 64.5 °, φ _εIImax = 162.5 ° in the interval of the crankshaft rotation angle corresponding to the implementation of the expansion stroke in the decompressed II cylinder, do not exceed standard values, therefore, the technical condition of the elements of the gas distribution mechanism of the exhaust valve I of the cylinder and the intake valve of the III cylinder working in this period corresponds to their normal functioning;

since there are no angular acceleration extrema with identical phase increments relative to their nominal values (phase positions of the maximum values of angular accelerations φ _εIImax = 162.5 °, φ _εIVmax = 161.5 ° differ by 1 ° and are within acceptable limits, and by minimum extrema - Δ _φεIImin = 64.5-64.0 = 0.5 °, Δφ _εIVmin = 64.0-56.5 = 7.5 °), then the kinematic chain of the mechanism for setting the standard values of the gas distribution phases is in good condition;

amplitude values A _εIV = 179.5 rad / s ² > A _{ε nom} = 205 ± 15 rad / s ² and the phase shift of the minimum extremum Δφ _εIVmin = 56.5-64.0 = 7.5 °> φ _{εmin nom} = 64 , 0 ± 2.0 ° of angular acceleration in the interval of the angle of rotation of the crankshaft corresponding to the implementation of the expansion stroke in the decompressed IV cylinder, exceed the permissible standard values of these diagnostic parameters. Therefore, the cause of the malfunction of the gas distribution mechanism is determined by the violated structural parameters in the operation of the drive mechanism of the exhaust valve II of the cylinder or intake valve I of the cylinder. When checking the state of the gas distribution mechanism (removing the cover from the distribution mechanism), the cause of the gas distribution mechanism malfunction was the lack of a thermal gap between the beam and the exhaust valve of cylinder II.

If the results of the first stage of diagnosing the gas distribution mechanism turned out to be positive, then similar operations are repeated when the engine is running at the same idle speed mode with an average angular speed ϖ = 50.7 ± 1 rad / s, but with a fourth (IV) working cylinder and decompressed I , II, and III cylinders. In this case, they diagnose and make a conclusion about the technical condition of the other parts of the gas distribution mechanism, operating during periods of 0 ... π, 3π ... 4π (Fig. 1) of crankshaft rotation, in which expansion strokes are carried out in decompressed I and III cylinders.

The developed method for diagnosing the gas distribution mechanism of an internal combustion engine eliminates the main drawback of the known method, namely, it significantly improves accuracy by eliminating the operation of cranking the engine crankshaft with an external drive device (starter), which introduces an additional error from the dynamic interaction of the starter gear with the ring gear of the engine flywheel. In the proposed method, the crankshaft is rotated due to the stored kinetic energy from the operation of the internal combustion engine on one cylinder. Therefore, the measured values of the instantaneous angular velocities and the values of the amplitudes and phases of the extrema of the angular acceleration of the crankshaft determined by them will be more accurate and independent of the technical condition of the “starter - flywheel crown” gearing. In addition, the method extends the range of diagnosed elements of the gas distribution mechanism, in particular, determines the common cause of its malfunction due to improper installation of parts of the camshaft drive mechanism, which violates the installation angles of the gas distribution phases.

The proposed method for diagnosing the gas distribution mechanism is most expedient to use in systems of built-in (on-board) diagnostics and automatic control of the operation of 2-, 4- and 6-cylinder engines, in which the design provides for the installation of a crankshaft speed sensor.

Information sources

1. USSR Copyright Certificate No. 1307275, cl. G01M 15/00, 1987.

2. USSR copyright certificate No. 1160262, cl. G01M 15/00, 1985.

3. Copyright certificate of the USSR No. 1302163, cl. G01M 15/00, 1987.

4. Copyright certificate of the USSR No. 1437716, cl. G01M 15/00, 1988 (prototype).

5. Lukin A.M., Khavkin V.I., Yarovoy V.K. Algorithmic features of automation of measuring the degree of identity of successive cycles and the stability of the internal combustion engine by the uneven rotation of the crankshaft // Dvigatelestroyenie. 1984, No. 4, S.24-26.

6. Diagnosis of the technical condition of automobiles at automotive enterprises / L.V. Miroshnikov, A.P. Boldin, V.I. Pal and others. - M.: Transport, 1977, - 263 p.

7. Komarova N.I., Korchemny L.V. Power losses in gas distribution mechanisms // Automotive Industry, 1990, No. 9, S.12-13.

Claims (1)

A method for diagnosing a gas distribution mechanism of an internal combustion engine, namely, that the engine cylinders are decompressed, the crankshaft is scrolled at a given speed, a change in the angular velocity of the crankshaft is recorded within the full kinematic cycle, characterized in that the crankshaft is scrolled during engine operation idle on one cylinder while the rest are decompressed, the dependence of angular acceleration is determined by changing the angular velocity I of the crankshaft from the angle of rotation for periods corresponding to the expansion strokes in decompressed cylinders, determine the values of the amplitudes and phases of the extrema of the angular accelerations of the crankshaft in these periods and, based on their deviation from the standard values, draw a conclusion about the technical condition of the gas distribution mechanism.

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