PROCEDURE AND DEVICE FOR THE INVESTIGATION OF FRICTION SYSTEMS IN ENGINES.

METHOD AND ARRANGEMENT FOR DIAGNOSTICS OF FRICTION SYSTEMS OF MOTORS

This invention relates to the method for diagnostic of friction systems of motors based on analysis of unused and used lubricant and to an arrangement for carrying out this method.

The analyses of used motor oils, especially by largescale users of oil combustion engines, have been practiced since many years. With the development of more efficient motors and better lubricants some of the old-fashioned and inconvenient methods based above all on the classical chemical analysis had to be abondoned. It happened in recent years when the results of analyses began to be widely used for estimating and control of the functioning state of motors and kinetic mechanisms. This use is based on the fact that while the motor or the mechanism is on microparticles of metals of which the mechanism consists get transferred into the oil or the lubricant.From concentrations of individual metals and from their time changes it is possible to estimate objectively the degree of wear and the technical state of the motor, to detect in time an imminent damage atc., provided certain standard conditions for the analysis are maintained.

For carrying out these analyses two methods have proved best suited so for: the atomic emission spectrography /AES/ and the atomic absorption flame spectrometry /AAS/. Lately the latter one is mostly preferred; in it the sample of oil after filtering and dilution by an appropriate solvent is burnt in a special burner while the absorption spectrum is measured by a highly sensitive apparatus. In spite of high cost, operation complications, unfitness for current workshop conditions and other limitations /see below/ the spectral tribodiagnostics is at present the most successful and widely applied method of objective triboanalysis, used especially in USA, Canada and western Europe. There exist other methods of technical diagnostics like vibration and acoustic method and methods based on estimation of combustion products.Their main disadvantage is that they indicate as a rule only the critical states of the motors being not sufficiently sensitive and exact. For the lack of relatively cheap, sensitive and simple methods and arrangements for objective tribodiagnostics without dismantling motors the prevailing methods in majority of countries are costly and laborious methods requiring dismantling.

One of the limitations and drawbacks of the above spectral tribodiagnostic methods is the circumstance that the informations they provide concern the total concentration of the elements and not the form in which they occur, like their oxidation states. They do not allow determination of organic components of the samples or detection of changes in lubricants, for some non-primary metals like lead their sensitivity is limited, restricted or impossible is their direct applicability for analysis of dispersed abraded particles larger than 10 mu m. Disadvantageous is their relatively high cost, restricted use in current workshop conditions, limited precision, bulkiness, etc.

These disadvantages are absent in the method of diagnostics of friction systems of motors and an arrangement for carrying out this method, according to the present invention.

Basic point is the experience that the diagnostic information obtained from AAS or AES and from technical check-up of oil combustion engines is in agreement with the intensity and the changes of current signal in the current-voltage dependences measured according to the described method under maintenance of certain experimental conditions. To the necessary experimental conditions belong, besides an appropriote apparatus and equipment, especially strict following of a certain working procedure in preparing the sample of the solution for analysis, in preparing the detection mercury electrode or microelectrode and in recording the current-voltage dependence or its function. The modern voltammetric methods are used with advantage for this purpose.The utilization of small-size mercury electrodes, the so-called mini- and microelectrodes, proved especially convenient from the point of view of economy of space and simplicity of service, as well as of high reproducibility and advantageous electrochemical properties of the electrode.

The method of diagnostics of motors according to the present invention widens considerably the scope of objective tests of the state of combustion engines and other motors in view of detection and timely repair of minor defects, timely planned major repairs and avoiding unexpected break-downs. Providing that the diagnostic system is manufactured in a high standard new possibilities will open for the repair and maintenance practice, as the financial accessibility of the present method is more than 10 times more favourable than the spectral methods.

EXAMPLE No 1

An example of application of the present invention is an estimation of the degree of wear of an oil combustion engine which is done as follows. From the lubrication system of the motor warmed-up to the usual operating temperature a sample of oil is taken. 5 g of this oil after addition of 3 ml of solvent based on chlorinated hydrocarbons is covered by 5 ml of hydrochloric acid diluted in proportion 2:1 and an extraction of the microparticles from oil into the aqueous solution is carried out for 15 minutes. Then after addition of 45 ml of water the extraction is continued for 10 more minutes.After separation of phases to 10 ml of aqueous phase 5 ml of 6M potassium hydroxide are added and after dissolution of 2-3 g of sodium sulphite in the mixture the resulting solution is placed in the cell and after connecting the source of linearly increasing voltage to the measuring mercury electrode and the reference silver chloride electrode a current-voltage curve is recorded in the potential range -0.24 to -1,70 V at the rate of voltage scan of 20 mV/sec. The measuring electrode is realized ba a droplet of mercury of radius about 0.3 mm formed in a given moment at the orifice of a special capillary by delivery of the appropriate micro-amount of mercury from the mercury reservoir. After recording of the above curve 10 ml of 0.1N triethanolamine are added to the solution in the cell and after stirring a current-voltage curve is recorded in the range -0.6 v to -1.2 V.From the course and comparison of both recordings the concentration of copper, lead, zinc and iron in the motor oil is determined and by means of calibration data the extent of wear of the friction system of the oil combustion engine is estimated.

The magnitudes of the measured signals or of the determined concentrations are plotted into graphs, e.g., as a function of mileage covered by the vehicle with the motor which is being followed. An increase of the measured signals or of the determined concentrations over a certain level indicates the accurrence, the cause or even the possible location of a failure. Fig. 1 shows a graph of the dependence of copper / curve 102/, lead / curve 101/ and zinc / curve 103/ concentration in the extraction solution as a function of covered mileage. The exponential increase of concentration of these metals indicates wear of bearings. The position of maxima on the curves corresponds to the state of the motor before its break-down, the steep decrease to the state after repair.

EXAMPLE No 2

A sample of 5 g of used oil is taken from the lubricating system of the motor, after addition of 5 ml of a solvent based on chlorinated hydrocarbons the solution is extracted for 5 minutes by 5 ml of 3M HCl and then a sample of 5 ml of aqueous extract is taken. Into this sample sodium pyrophosphate and triethanolamine are added up to concentration of 0.1 mol/l. Then the acidity of the sample is adjusted by addition of 1M NaOH to pH=9, whereupon the measuring electrode based on mercury drop and the silver chloride reference electrode are dipped into the sample of the extract, on the measuring electrode and reference electrode voltage is applied linearly increasing from -0.1 v to -1.5 V at the rate of 50 mV/s while a current-voltage curve is recorded.From the hights of peaks or waves formed in the region of -0.3 V and -0.9 V the concentration of ions of iron in valency II and III is determined and from the data thus gained and compared with standard samples the abrasive properties of the metal present in the used oil can be determined as well as the total wear of the motor, the cylinder struts, the pistons, etc. The measured signals are plotted in graphs in dependence on covered mileage.

In the drawing are shown some advantageous embodiments of the arrangement according to the invention.

Fig. 1 is a diagram of the metal contents in the lubrication oil in relation to the running operation of the engine. After a driving distance of about 7500 km the concentration of Zn, Pb and Cu in the oil increases suddenly, so that the lubrication oil of the automotive-engine should be changed.

In the arrangement of Fig. 3 a block 1 for setting a program is connected with a block 2 for voltage or current generation. Said block 2 is connected to a block 3 of an electrode detector combined with a measuring system 4 on one hand and a block 5 for sensing, processing and evaluating the signal combined with a block 6 for recording and display on the other hand. According to need, a block 7 for extractor and/or sample treatment is connectable for a determined period with the block 2 for voltage or current generation, with the block 3 of the electrode detector or with a feeding block 9. A block 8 for sample dosing is connected in series or in parallel to said block 7 and to the system 4. The feeding block 9 is connected with the block 2 for voltage or current generation and/or with the block 8 for sample dosing and/or with the block 7 for extractor and/or sample treatment.

As shown in Fig. 2 the block 3 of the electrode detector comprises advantageously a block 10 of setting connected with the block 11 of timing and control. To this block 11 are connected in parallel a block 12 for starting, a block 13 for feeding, a memory block 14 and a block of electrodes 15. The block 11 is further boundable in parallel with a block 16 of electro-mechanical accessory, a block 17 of spare voltage or current outputs and a block 18 of signals and control. Said control block 18 is connected also with the block 10 of setting, the block 12 of starting and/or with the block 11 of timing and control. In certain cases the block 12 for starting is bound independently to a block 19 of external control.

Fig. 4 shows some examples of the block 15 of electrodes containing a measuring electrode 26 where a capillary closure 20 of a capillary member 21 includes a constricting spike 22. The size and shape of said spike or needle 22 correspond to the size and shape of a capillary orifice 23 in the capillary closure 20 or to the size and shape of at least one part of the inner space 59 of the capillary member 21. In the upper part of the body of the measuring electrode 26 is adjusted a case 24 in which a spring loaded 63, 66 control mechanism 25 supporting the spike 22 is disposed.

In the arrangements according to Fig. 5 and 6 the block 3 of electrode detector is constructed on the basis of a renewed mercury mini- and microelectrode. As in the example of Fig. 4 in the body 26 of the measuring electrode is adjusted a case 24 with a fixed control mechanism 25 or with its part and with a sliding mechanism 27. A sliding segment 28 of the control mechanism 25 forms a component of the constricting spike 22 which passes through a closure 32 into the inner reservoir of mercury 29. The wall of the case 24 is provided by a lifting lever mechanism 30 with a lock 31.The spike 22 is connected with the sliding segment 28 of the control mechanism 25 or is adjusted into its shape while at least in the passage through the closure 32 the difference between the outer diameter of the constricting spike 22 and the inner diameter of the closure 32 is less than 0.7 mm and the surface coarseness of the constricting spike 22 in the part passing through the closure 32 does not exceed 0.3 mm. The closure 32 is provided with a packing 33, an electric contact 34 to the constricting spike 22 or to the sliding segment 28, an independent electric contact 35 in the wall of the inner reservoir 29 and with an external reservoir 37 connected to the inlet of a mercury 36 and provided with a valve 38 or an overpressure doser 39. A stop 40 is formed in the inner reservoir 29.A reducing piece 41 at the lower part of the body of the measuring electrode 26 is shaped so as to fit its input 42 in a bead or in a wall opening of the arrangement in which the electrode is held. In the lower part of the reducing piece 41 is fixed a packing membrane 43. A mercury drop dislodging device 44 attacks the reducing piece 41, the body of the measuring electrode 26 or the capillary wall 21. For adjusting the amplitude of a hammer 45 an adjustable mechanism 46 is provided which can be shifted along the axis of the hammer 45. The essential parts of the dislodging device 44 are the hammer 45, an elastic element 47, a force element 48 and a case 49 (Fig. 6 right side).

In the arrangements according to Fig. 7, 8 the block 10 of setting, the block 11 of timing and control, the block 12 of starting, the memory block 14, the block 18 of signals and control and, according to need, even the block 13 for feeding are designed and disposed in a screened and encased partable controlling block 50 which is connectable to the block 15 of electrodes on the basis of the measuring electrode 26 to the drop dislodging device 44 and to a disassemblable stand 51. Clamps are provided for connecting the body of the measuring electrode 26, for a reference electrode 52, for an auxiliary electrode 53, for a stirrer 54, for a doser of gas 55 chamically inert towards the material of the used system, for an external reservoir 56 and, according to need, even for the overpressure doser 39, for the measuring system 4, for fixing a waste pan 57 and a stabilizing support 58.

Fig. 9 shows a set of capillaries 21 in which the inner bore 59 in the upper part has the form of a funnel-shaped saddle 60 or of its part, and in the lower part there are, in a given sequence, sections of cylindrical, conically widening and conically narrowing diameters, down to the orifice 61 of the capillaries 21. Other accessories of the arrangement are an evacuation arrangement with an adapter corresponding by its shape and size to the lower end of the capillary 21, the overpressure doser 39, a protective tube for the capillary 21 and a protective case.

The arrangement shown in Fig. 10 includes a pen-shaped body of the measuring electrode 26 consisting of an electrode clamp 62 of the capillary 21 connected to the inner reservoir 29 with an independent electric contact 35. Above the inner reservoir 29 is mounted the control mechanism 25 for reproducibel oneway or periodic shifts of the constricting spike 22. Said mechanism 25 is coupled with the starting mechanism 63 on the bsis of a push button, a spring and a limiting stop and a release 64.

As shown in Fig. 11 the control mechanism 25 can include a mechanical system on the basis of the sliding segment 28 with an elastic neck 65. A rod 66 of the starting mechanism 63 is designed in the shape of a pointed cone and disposed above the neck 65. A fixing grip 67 is provided with an elastic segment 68 and an adjustable stop 69.

In the arrangement shown in Fig. 12 the block 7 of extractor and/or sample treatment contains an arrangement in which a closed extraction cell 70 is provided in its upper part near the wall by an inlet neck 71. A shaped segment 72 is fixed inside the closed extraction cell 70. An inlet tube 73 passes through the inlet neck 71 and ends near a channel 74 close to the bottom of the closed extraction cell 70 below a rotating stirrer 75. In the wall of the shaped segment 72 is formed a slit 76 and an outlet line 77 leads from the side wall of the closed extraction cell 70 to a collecting cell 78. An upper reservoir 79 with a stopcock is connected with the inlet neck 71 and the whole arrangement is supplemented, according to the need, by a mineralizing unit for chemical dissolution of the sample or for its incineration.

Another example of a more detailed block scheme of the arrangement of the whole system is shown in Fig. 13 where the block of voltage or current generation 2 is formed by the block of timing pulses 80, block of sum 81, block of scanning ramp 82 and the block of voltmeter 83, further the block of the electrode detector 3 contains the block of electrodes 15, the block of programmed electrode control 84 and the block of manual control 85, the block of sensing,processing and evaluating the signal 5 contains the block of interface 86, block of electronic memories 87 and the block of amplifier and filter output 88 and where the block of recording,evaluation and control of the system 89 includes the block for sensing,processing and evaluating the signal 5 and the block for recording and display 6 while in the given arrangement the output of the block of polarity and setting 90 is connected with the block of scanning ramp 82 the first output of which is led to the input of the block of voltmeter 83 and the second output to the first, input of the block of sum 81,while the outputs from the block of sum 81 are connected to the reference and auxiliary electrodes of the measuring system 4 into which dip in parallel the measuring sensor and the stirrer of the block of electrodes 15,the output of which is led to the input of the block of interface 86,connected further to the input of the block of electronic memories 87 the output of which is led to the input of the block of amplitier and filter output 88 while further the second input of the block of sum 81 is joined with the output of the block of timing pulses 80,its input is connected with the output of the feeding block 9,interconnected further with the block of manual control 85 the first output of which is joined with the input of the block of programmed electrode control 84 led to the input of the block of electrodes 15 and where the second output of the block of manual control 85 is connected to the block for extractor and/or sample treatment 7.

Fig. 14 shows the example of a block scheme of a variant block of the electrode detector 3 where the block of timing and control 11 contains the block of microprocessor 90 and the block of program generator of time pulses 91 while the block of external control 19 is connected with the block for starting 12 which is bonnd to the block of microprocessor 90 and the memory block 14 and where the block for starting 12 is independently connected to the block of setting 10 on basis of a key-board and to the block of electrodes 15,and,at the same time, the block of microprocessor 90 is joined to the block of signals and control 18,and,in parallel, to the block of program generator of time pulses 91.The block of signals and control 18 consists in that case of an optical part and an acoustic part and the block of external control 19 contains an electronic pulse system started automatically or by a mechanical impulse.

References Cited K. J. EISENTRAUT et all.:Anal.Chem. 56,No.9,/1984/ ,pp.1087 E. ROBERTS et all.:Anal.Chem. 54,/1982/,p.975-9 J.R. BROWN et all.:Anal.Chem. 52,/1980/,p.2365-370