RU2542470C2 - Testing method and unit of ageing processes of motor oils - Google Patents

Abstract

FIELD: test equipment.

SUBSTANCE: group of inventions relates to test of motor oils and is used for testing their ageing processes. During the test, oil is heated, cooled and mixed, circulated under pressure, centrifuged, aerated by humid air and waste gases, compressed and sprayed under pressure to perform hydromechanical, thermochemical and thermodynamic destruction, thus providing simulation of operation of oil both in a motor lubrication system and in its cylinder-and-piston group, sliding bearings of a crank shaft and in a gas-distributing mechanism. Oil quality is assessed by testing of physical and chemical properties of samples taken during the test as per a special formula. The unit includes a temperature control tank with a mechanical mixer, thermometers, pressure gauges, control valves, heaters, a cooler, oil lines, an oil pump, a centrifuge, regulating valves, a hydraulic accumulator, a high pressure injector, a brazing fuel-burning lamp, a compressor, a storage tank, a receiver and valves that allow performing processes of hydromechanical, thermodynamic and thermochemical destruction during cyclic tests performed as per certain modes.

EFFECT: improvement of test informativity and reliability.

2 cl, 1 tbl, 4 dwg

Description

The group of inventions relates to mechanical engineering, and in particular to installations for studying the aging processes of motor oils that mimic their working conditions in internal combustion engines.

It is known that engine oil is used to lubricate the rubbing parts of an internal combustion engine. The main function that engine oil performs is to reduce friction and wear on the friction surfaces of parts by creating an oil film on their surface. Modern motor oils are base oils with the addition of various functional additives that improve the base of the oil, or give the oil the required performance properties. Reliability and durability of the engine to a large extent depends on the quality of engine oil. However, during operation, engine oil under the influence of various factors (high temperature and pressure, contamination by mechanical impurities and water, ingress of fuel and coolant into the oil, oxidation of oil hydrocarbons and accumulation of oxidation products) changes its properties. The process of changing physico-chemical and operational properties is called the aging process.

Aging of engine oil during operation is an inevitable phenomenon, therefore, the study of these processes and monitoring the dynamics of their development is an important scientific and practical task.

A known installation for testing motor oils (AS SU 1587442 A1), comprising a crankcase with an oil bath, a varnish former, a heating element and an oil intake in the form of a movable ring for supplying oil to the wall of the varnish former. The disadvantage of this installation is the lack of devices to produce mechanical and chemical degradation of oil.

A known friction machine (patent RU 2290622 C1) for testing materials and lubricants with dynamic control of loading parameters and reverse motion at low relative speeds. The friction machine contains a base, a counter-sample holder mounted on it, a horizontal movement carriage and a test sample holder, a loading device and a loading drive. The disadvantage of the machine is another design purpose. It serves to study the effect of oil on the friction and wear of a sample and does not establish how the loss of working capacity of the oil itself occurs.

The closest (prototype) to the claimed invention is a method for the study of lubricants and a device for its implementation (patent RU 2285918 C1). A device for implementing a method for the study of lubricants contains an oil tank-thermostat with a mechanical stirrer, a heat heater with a thermometer and a pipeline with a valve, and is also equipped with a pump, a throttle valve and a degassing device. The disadvantage of this installation is the lack of real elements of lubricating systems and ICE components that allow more accurately simulate the operation of motor oil in the engine.

The aim of the invention is to develop an installation and a method for studying the aging processes of motor oil and determining the longevity of its work.

The developed facility for studying the aging processes of engine oil in ICE is a physical model that allows you to simulate the oil in the engine lubrication system and determine the process statics and kinetics based on changes in the physicochemical properties of the oil.

Installation for researching the aging processes of motor oil contains (figure 1): oil tank-thermostat 1; heating element 2; stirrer 3, thermometer 4; receiver 5; valve 6; gas blowtorch 7; storage tank for burned gases 8; compressor 9; valves 10 and 11; manometers 12 and 13; electric drive 14; oil pump 15; coarse filter 16; manometer 17; oil line 18; pressure reducing valve 19; centrifuge 20; pressure gauge 21; radiator 22; drain valve 23; safety valve 24; drain line 25; control valves 26, 27 and 28; devices 29, 34 and 39; oil lines 33, 38 and 45; thermometer 46; manometer 47. In addition, the device 29 consists (Fig. 2) of a steel cylinder 30, a heat-insulating layer 31, a heating element (TEN) 32. The device 34 consists (Fig. 3) of a vertical cylinder 35, a heating element 36, and a vertical tube 37 and the device 39 (Fig. 4) is from a hydraulic accumulator 40, a check valve 41, a high-pressure nozzle 42, a high-pressure oil pipe 43, and a chamber 44.

Installation for researching the aging processes of motor oil works as follows.

The preparatory phase of the test. The engine oil is poured into the oil tank thermostat 1. The heating element 2 and the mixer 3 are turned on. The heating element 2 heats the engine oil in the oil tank thermostat 1 to an operating temperature of 100-110 ° C, and the mixer ensures its uniform heating throughout the volume. The oil temperature is controlled by a thermometer 4. Simultaneously with heating the oil to simulate the process of exposure to oil of exhaust gases and moist air in the developed installation, they are prepared for supply to the oil tank-thermostat 1 from receiver 5 through valve 6, which allows you to adjust the required supply of a mixture of exhaust gases and moist air. The process of accumulation of exhaust gases in the receiver 5 occurs in the following sequence. A gasoline blowtorch 7 is ignited and inserted with its ejector into the storage tank of burned gases 8. The gases in the storage tank 8, mixed with air, are accumulated in it and are pumped through valve 9 and 11 to the receiver 5, where they are under pressure before the test. The pressure in the receiver 5 and the storage tank is controlled respectively by pressure gauges 12 and 13. After the gas pressure in the receiver 5 reaches a value of 0.5-0.6 MPa, the blowtorch 7 and the compressor 9 are turned off, and the valves 11 and 10 are closed. The preparatory phase ends there.

The main stage of testing. The electric drive 14 of the oil pump 15 is turned on, which transfers the oil heated to the operating temperature from the oil tank thermostat 1. The oil is pumped by the pump 15 through the coarse filter 16 and supplied under pressure controlled by a manometer 17 through the oil pipes 18 through the pressure reducing valve 19 through the oil pipe in a full-flow centrifuge 20. The pressure at the oil outlet from the centrifuge is controlled by a pressure gauge 21. The maximum allowable oil pressure values at various parts of the installation system are set in accordance with the modes given in the table. If during the test the oil pressure at the outlet of the centrifuge becomes greater than 0.7 MPa, then the oil is bypassed through a pressure reducing valve 19 along the bypass line, bypassing the radiator 22 into the oil line before the drain valve 23. If the pressure in the section of the oil line from the centrifuge 20 to of the radiator 22, controlled by a pressure gauge 21, does not exceed 0.7 MPa, then the oil after the centrifuge 20 passes through the safety valve 24 and enters the radiator 22 for cooling to a temperature 10-20 ° C lower than in the oil tank-thermostat 1. V case e, if there is a large hydraulic resistance in front of the radiator 22 in this section, the bypass valve 24 will release the oil pressure through the drain line 25 to the oil tank thermostat 1. If the oil pressure corresponds to the operating value, the oil will pass through the radiator 22 and valve 23 to the control valves valves 26, 27 and 28, and then the oil flow is divided into three streams.

The first flow through the control valve 26 will enter the device 29, simulating the operation of oil, both in temperature and in pressure, in the sliding bearings of the crankshaft of the engine (see figure 2). The oil enters the device 29, where it flows under pressure through the slotted channel formed by the inner surface of the steel cylinder 30, which is externally covered with a heat-insulating layer 31 and the outer surface of the heating element (TEN) 32. In this annular slotted channel, the oil is heated from the TENA 32 to a temperature of 150 -180 ° C. Leaving the device 29, the oil is freely drained through the oil line 33 into the oil tank thermostat 1.

The second stream through the control valve 27 (Fig. 1) enters a device 34 simulating the operation of oil, both in temperature and pressure, in the cylinder-piston group of the engine (see Fig. 3). The oil flow supplied to the device 34 is sprayed into a vertical cylinder 35, the inner surface of which is heated by a heating element 36 to a temperature of 250-350 ° C, through a vertical tube 37 located inside the vertical cylinder 35, which is connected to a control valve 27 and has holes located both around the circumference and along the height of the tube. After spraying onto the hot wall of the vertical cylinder 35, the oil flows by gravity from it through the oil pipe 38 into the oil tank-thermostat 1.

The third stream through the control valve 28 (Fig. 1) enters a device 39 simulating the operation of oil, both in temperature and pressure, in the friction pairs of the engine gas distribution mechanism (see Fig. 4). The oil is supplied to the device 39, which is a combination of several elements, namely: through the valve 28, the oil enters the accumulator 40 through the check valve 41. The accumulator 40 is charged to the pressure at which the oil is supplied to the nozzle 42 through the high pressure oil pipe 43. Nozzle 43, installed in the chamber 44, under a pressure of 20 MPa periodically injects oil onto the walls of the chamber 44, which flows by gravity through the oil pipe 45 into the oil tank-thermostat 1.

The oil temperature in the installation before the separation of flows is controlled using a thermometer 46, and the pressure according to the manometer 47.

To ensure the effect on the engine oil circulating in the laboratory installation of moist air and exhaust gases, they are supplied in the form of a free outlet through the control valve 6 (Fig. 1) from the receiver 5 to the bottom of the oil tank-thermostat 1, resulting in wet oil bubbling air and exhaust gases.

Changing the simulation operating conditions of the laboratory installation is carried out by changing the performance of the oil pump, for which the rotational speed of the rotor of the drive induction motor of the electric drive 14 is changed by changing the frequency of the supply voltage. The pressure in the system of the laboratory installation is changed using control valves 26, 27 and 28. The amount of air and gases passing through the oil is controlled by valve 6, and the temperature of the oil in the installation is controlled by heating elements 2, 32 and 36 and a radiator 22.

The main stage is carried out within 7 hours, simulating the operation of oil in the engine during the working day. After 7 hours of testing, the electric drive 14 is turned off, and an oil sample in the volume of 500 ml is taken from the oil tank for physicochemical analysis, and fresh oil in the volume of 500 ml is added to the tank. At this, the main stage of the test ends. Tests are repeated daily. The number of test cycles depends on the speed of the oil aging process, which is controlled by an estimate or determined by the test program and the estimated number of cycles.

The oil selected for analysis is subjected to standard performance evaluation methods. During standard tests, it is determined: oil density, kinematic viscosity, alkaline number, flash point, pour point, corrosion, thermo-oxidative stability. Oil quality assessment in the process of its analysis is carried out according to the generalized criterion E _about , the value of which for a healthy oil should be in the range from 0.7 to 1.3.

Indicator E _{about is} determined by the results of the analysis of each oil sample taken from the installation, according to the formula:

E _about = (ν _n / ν _m ) · (ρ _n / ρ _m ) · (K _n / K _m ) · (LV _n / LV _m ) · (TV _n / TV _m ) · (Tn _n / T _m ) · (Tc _n / Tc _m ), (1)

where ν _n , ν _m - respectively, the kinematic viscosity of the new and used oil, mm ² / s;

ρ _n , ρ _m - respectively, the density of the new and working oil, kg / m ³ ;

To _n , To _m - respectively, the corrosivity of the new and working oil, g;

RN _n , RN _m - respectively, the alkaline number of new and used oil, mg KOH / g;

Tv _n , Tv _m - respectively, the flash point of the new and used oil, ° С;

Tz _n , Tz _m - respectively, the pour point of the new and used oil, ° C;

TS _n , TS _m - respectively, the thermo-oxidative stability of the new and used oil,%.

If the generalized indicator E _about goes beyond the specified limits, then the oil must be completely replaced, i.e. his resource has been exhausted. In this case, the oil test is stopped and the time of its operation in the engine is determined according to the formulas below.

Calculation of the oil test time and the number of oil test cycles in the laboratory setup is carried out according to the formulas below. The engine oil test time is determined from the relationship:

$$T_{\mathrm{at}\mathrm{from}t}=T_{R.m.}/{\mathrm{TO}}_{\mathrm{at}\mathrm{from}\mathrm{to}},h\mathrm{but}\mathrm{from},(2)$$

where T _r.m. - the operating time of the oil in the engine, hour, defined as

$$T_{R.m.}=L/V_{\mathrm{but}},h\mathrm{but}\mathrm{from},(3)$$

where L is the vehicle mileage recommended by the manufacturer before changing the oil, km;

V _a - average operational speed of the car, km / h;

K _accele - coefficient of acceleration of oil tests in a laboratory setup, which is defined as

$$K_{\mathrm{at}\mathrm{from}\mathrm{to}}=(K_{c.\mathrm{at}.}\cdot E_m)/(N_{\mathrm{uh}}\cdot K_{c.d\mathrm{at}.}),(\mathrm{four})$$

here To _c.u. - the frequency of circulation of oil in the installation, h ^-1 ,

$$K_{c.\mathrm{at}.}=V_{n.\mathrm{at}.}/V_{m.b.},h^{-\mathrm{one}},(5)$$

where V _n.o. - volumetric oil supply by the pump of the laboratory setup, l / h;

V _m. - the volume of the oil tank installation, l;

To the _{central door} - the frequency of oil circulation in the engine, h ^-1 ;

$$K_{c.d\mathrm{at}.}=V_{n.d\mathrm{at}.}/V_{m.\mathrm{to}.},h^{-\mathrm{one}},(6)$$

where V _n.dv. - volumetric oil supply by the internal combustion engine pump, l / h;

V _m.k. - engine oil sump volume, l;

N _e - electric power of the installation, kW;

E _m - power destructive effects acting on the oil in the engine, kW, which can be roughly estimated as

$$E_m=8,34\cdot {10}^{-9}\cdot g_e\cdot N_e\cdot H_u,\mathrm{to}\mathrm{AT}t,(7)$$

where g _e - passport specific effective fuel consumption in the engine, g / (kW · h);

N _e - passport effective engine power, kW;

H _u - net calorific value of fuel, kJ / kg. For gasoline, H _u = 43500-44000 kJ / kg, and for diesel fuels H _u = 41500-42500 kJ / kg.

The number of test cycles is defined as

$$N=T_{\mathrm{at}\mathrm{from}t}/7,ed.(8)$$

Table 1 Installation Modes No. p / p the name of the operation Equipment, materials, tools Lead time Installation Modes one Testing the laboratory setup Visually Before turning on the unit, check the grounding. 0.01 2 Preparatory stage AC 220 V, electric heater TEN, mechanical stirrer with electric. driven, gas blowtorch, compressor To heat the oil to a temperature of 110 ° C, the heating time - 30 minutes, power el. heater - 4 kW. Pump exhaust gases into the receiver until a pressure of 0.6 MPa is reached, then turn off the compressor and close valves 10 and 11. 0.5 Switch on the electric heater and mixer in the thermostat tank, light the gas blowtorch, switch on the compressor 3 The main stage of testing 380 V AC mains, engine oil test rig 7.0 Turn on the electric drive of the pump, at a constant oil temperature, change the pressure in the system with control valves for 7 hours. Operating modes -P = 0.1 MPa, t = 23, T = 110 ° C -P = 0.2 MPa, t = 23, T = 110 ° C -P = 0.3 MPa, t = 23, T = 110 ° C four The final stage After shutting down the unit, the oil should be cooled for 30 minutes at ambient temperature 0.5 Turn off the electric drive of the pump and the mechanical mixer, turn off the electric oil heater, shut off the exhaust gas to the thermostat tank 5 Take a sample of oil for analysis Sampler 0.01 The amount of oil for analysis - 500 ml 6 Add fresh oil to the thermostat Beaker 0.01 To compensate for the loss of oil taken for analysis 7 Perform engine oil quality control A set of necessary equipment for monitoring the quality of oil products Oil quality control is not included in the scope of testing 8 Visual inspection. If necessary, wipe with a cotton cloth possible leaks of oil Carry out monitoring of the state of the installation after a test cycle Rags, cotton fabric 0.1 9 Cooling oil at ambient temperature for 16 hours In the laboratory room before the next test cycle

Claims (2)

1. A method for studying the aging processes of motor oil by performing hydromechanical, thermodynamic and thermochemical destruction, including heating to a predetermined temperature, mixing, aeration, circulation through the pipeline, characterized in that aeration and thermochemical destruction of the oil is carried out by feeding to the tank thermostat from the receiver through valves with a compressor of humid air and exhaust gases ignited by a blowtorch in a storage tank, hydromechanical destruction is carried out by changing the pressure in the device by changing the speed of the oil pump, the capacity of the control valves, compressing the oil in the accumulator, centrifuging and spraying from the nozzle under high pressure, thermodynamic destruction is carried out by heating the oil in the thermostat tank and devices that simulate the operation of oil in the cylinder-piston group of the internal combustion engine and the bearings of the crankshaft, in the process of testing the oil, it is monitored temperature and pressure, the power of electric heaters and electric laboratory equipment, oil quality assessment is carried out after sampling through a certain number of test cycles by laboratory analysis and calculation of the generalized criterion by the formula
E _about = (ν _n / ν _m ) · (ρ _n / ρ _m ) · (K _n / K _m ) · (LV _n / LV _m ) · (TV _n / TV _m ) · (Tn _n / T _m ) · (Tc _n / Tc _m ),
where ν _n , ν _m - respectively, the kinematic viscosity of the new and used oil, mm ² / s;
ρ _n , ρ _m - respectively, the density of the new and working oil, kg / m ³ ;
To _n , To _m - respectively, the corrosivity of the new and working oil, g;
RN _n , RN _m - respectively, the alkaline number of new and used oil, mg KOH / g;
Tv _n , Tv _m - respectively, the flash point of the new and used oil, ° С;
Тз _н , Тз _м - respectively, pour point of new and used oil, ° C;
TS _n , TS _m - respectively, the thermo-oxidative stability of the new and used oil,%.
Moreover, the value of E _about for a healthy oil is in the range from 0.7 to 1.3, and when the value of E _about beyond the specified limits, the oil must be completely replaced. 2. Installation for researching the aging processes of engine oil, containing a tank-thermostat with a mechanical stirrer, thermometers, heaters, a coarse filter, oil lines and a pump, characterized in that it includes a series-connected pressure reducing valve 19, a centrifuge 20, a safety valve 24, radiator 22, drain valve 23, temperature sensors 46 and pressure 17, 21, 47 and connected in parallel through valves 26, 27, 28 of the device: 29 to simulate the operation of oil in the bearings of the crankshaft, consisting of steel core 30, insulation layer 31, heating element 32; 34 to simulate the operation of oil in a piston-cylinder group, including a vertical cylinder 35, a heating element 36, a vertical tube 37; 39 to simulate the operation of oil in friction couples of a gas distribution mechanism, comprising a hydraulic accumulator 40, a check valve 41, a high pressure nozzle 42, a high pressure oil pipe 43, as well as a set of devices for supplying atmospheric moist air and exhaust gases to a motor oil, including a gas blowtorch 7 for igniting these gases, which is inserted with its ejector into the storage tank 8 of burned gases, a compressor 9 for pumping gases mixed with air through valves 10 and 11 from the storage tank 8 into the receiver 5, pressure gauges 12 and 13 for measuring pressure, respectively, in the receiver 5 and in the storage tank 8, valve 6 for regulating the flow into the oil from the receiver 5 of a mixture of exhaust gases and moist air.

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