Investigation on the Effect of Lubricating-Oil Temperature on Deceleration Process of the Diesel Eng

JOURNAL OF CHINA ORDNANCEInvestigation on the Effect of Lubricating-OilTemperature on Deceleration Process of the Diesel EngineZHANG Geng-yun(张更云), WANG Xu-dong(王旭东), CHEN Man-qing(陈曼青),HE Lai-long(何来龙), WANG Pu-kai(王普凯)(Department of Mechanical Engineering, Academy of Armored Forces Eninering, Bejing 100072, China)oil temperature. To improve the evaluating accuracy of the diesel engine technical condition by using no-load decelerationprocess, the investigation on the deceleration process curve under various lubricating-oil tenperatures of a special-type ve-hicular diesel engine is conducted and the no-load deceleration curve tested under various lubricating-oil temperatures isnormalized. The normalied calculation method is searched. As a resut, the repeatability of the no-load deceleration curveis improved and the absolute time error of no load deceleration under various lubricaing oil temperatures is reduced.Key Words: deceleration time; diesel engine; lubricating-oil temperature; technical conditionCLC Number: TK421* .1Document Code: AArticle D: 1673-002X(2009)04-0251-05cal condition of the diesel engine.Introduction1 Analysis of Curve of DecelerationOwing to the limitation of the specialty of theProcess of Diesel Engine with Vari-maintenance system and the operation user of a specialpurpose vehicle, how to test and evaluate the techni-ous Lubricating Oil Temperaturescal condition of the main body of the diesel engine ofThe curves of the on- the- spot no load decelera-this vehicle is the problem needed to be solved urgent-tion process of the diesel engine with various lubricat-ly by the maintenance personnel of the vehicle.ing oil temperatures for a specal purpose vehicle areThe time of no-load deceleration of the diesel en-shown in Fig. 1. The registered motor-hour of thisgine was used to valuate the technical condition of thediesel engine is 261 h and the lubricating oil tempera-diesel engine, which was proposed in Ref.[1]. Itisaturesare51C，55C,60C，67Cand69Cre-practical testing method, but the repeatability of thespectivety. It can be seen from Fig.1 that, with thecurve of the deceleration process of the diesel engine isrise of the lubricating-oil temperature, the corrspond-strictly restricted under the condition of the same lu-ing deceleration time is elongated and the curve of thebricating oil temperature at the deceleration instancedeceleration process is flattened.of the diesel engine. However, in different areas orThe deceleration times corresponding to variousdifferent seasons, it is difficult to ensure the tempera-lubricating- oil temperatures are listed in Table 1 andture of the lubricating oil to be kept perfectly consis-Fig.2. The viscosity of the lubricating oil will be var-tent at the actual testing time. Therefore it is neces-ied with the variation of the lubricating-oil tempera-sary to adopt the method of temperature modificationture, and the variation of the viscosity of the lubricat-to modify the curve of the no load deceleration processing oil will affect directly the frictional force betweenof the diesel engine for determining the actual techni-the中国煤化工)f the diesel engineTHCNMHGReeired 2009. 04-20Biograpbies ZHANG Geng-yun(1966- -), professor, zgy718@sina. comJOURNAL OF CHINA ORDNANCE, 2009, Vol.5, No.4oil temperature.公1300-T:5IC- 69C2 Method to Modify the Lubricating-Oil Temperature1 00-The lubricating -oil temperature of the special900purpose vehicle in normal operation is above 50C. In700-the experiment of the on- the-spot no-load decelerationprocess of the diesel engine the average lubricating -oil5005temperature measured every time is also about 50 C .Therefore, 50 C is taken as the correction value forFig.1 Effeet of the lubricatigoll temperature on thethe lubricating-oil temperature.deceleration process under the on-the spot no-loadIn the on-the spot no-load deceleration process,conditionand the transmission system of the vehicle. Under thewhen the rotating speed is decreased from n1 to n2,condition of plenty lubrication, the viscosity of the lu-the variation of the corresponding energy isOE=(P:+ P1+ P.)Xt12,(1)bricating oil will be lowered with the rise of the lubri-cating-oil temperature, the friction forces between allwhere P; is the average friction power loss, which isfriction pairs will be lowered, and thus, the time ofdetermired only by the technical condition of theon the spot no-load deceleration process of the dieseldiesel engine delivered from the factory, composed ofthe average friction power losses in the main body ofengine will be increased.the diesel engine and in the parts or components mov-Table 1 Deceleration times for various temperaturesing together with the engine during n1 decreasing tolubricating- oil temperture/C 51 55 60 67 65n2, except the friction power loss increased due todeceleration time/s3.548 3.596 3.681 3.810 3.872the increase of motor hour; Pi is the average powerloss caused by the gas leakage equivalent through thegap between cylinder wall and piston and the friction3.9-power increased with the increase of the motor hour,of which the value has relation with operating intensi-ty and motor hour of the diesel engine; P。 is the oth-er power loss except the friction power loss and thegas leakage power loss, which contains the powerlosses from driving accessories, a small amount in3:5055606570proportion, has no great deviation, and is assumed tolubricating-oil temperauerCbea constant in the deceleration process; t12 is theFig.2 Relationship between the on-the-spot no load decel-deceleration time in the process from n1 to n2 witheration time and the lubricating-oil temperaturethe unit of s.Indicated by the experimental data, by the riseThe effect of P。on each diesel engine in on-the-of lubricating-oil temperature of 18 C, the decelera-spot no-load deceleration process is the same. Let ktion time from 1 500 r/ min to 500 r/ min will be elon-be the portion of energy loss accounting for OE,gated by 0.324 s, that is the relative error of 9.13% .caused by P。(wherek is a constant and k<1), fromOwing to the large deviation of error, the lubricating-expre中国煤化工oil temperature measured every time in the experi-CNMH G)t2.ment of the on-the-spot no-load deceleration processLet SE12=(1- k)OE,it n1 and n2 are deter-must be modified to be the corresponding lubricating-mined, then OE12 is a constant and we get:一252-ZHANG Geng-yun, et al. / Investigation on the Effet of Lubricating-Oil Temperature on Deeleration Process of the Diesel En-gineOE12 =(P;+ P)tn.(2)the diesel engine relevant to other lubricating-oil tem-If the total displacement of the special purposeperatures can be obtained, as shown in Fig.3, the av-vehicular diesel engine is 38.8 L，the number oferage friction power loss is lowered with the rise ofcylinder is 12, the working volume of the cylinder V。=the lubricating -oil temperature.3.233 L, and the piston stroke S=0.18 m, then, in4543-the on-the-spot no-load deceleration process of theE 41diesel engine from 1 500 r/ min decreased to 500 r/min, the average speed up of the piston can be calcu-lated, assuming the average rotating speed of thediesel engine is 1 000 r/ min:31up= sx100/30=0.18X1 000/30=6 (m/s)29From Ref. [2]:230一4050&0lubricatingoil temperatuecInv= -9.344 7+ 2. 9006ln@ -0.939 7(In@)2+ + 0.048 44(n0)'，(3)Fig.3 Relationship of the lubricating-oil temperature andthe relevant friction power of the diesel enginewhere V is the kinetic viscosity of the lubricating-oilUnder the condition that there is no combustion(m2/s)，日is the temperature of the lubricating-oiland n=1 600 r/min, when this type engine is justand the range of @:is 10~ 100 C.delivered from the factory, the maximum pressure inBased on expression (3), the calculated kine-the cylinder is pmax2, and the lubricating-oil tempera-matical viscosity of the lubricating-oil of a certain typeture is日. Then, without the combustion in theat temperature 90C is vgo, and U90= 18.341 7xcylinder, the average friction power of the diesel en10-6 m2/s, the kinematical viscosity of the lubricat-gine Pf,driven can be calculated from expression (4)ing-oil at temperature 50 C is U50， and U50 =and (5):76.4775x10-6 m2/s.P, drven =(34.5+0.011pmxe2+ 1.36up)XFrom Ref.[3-4], we get(vg/ v0).24x v.xixn/120x10-3. (6)Pf,dive =From expressions (4)~ (6), we also have(v/90)9.2*(34.5+0.011pmxa+ 1.36up), (4)P, diven= (P, divw/Pp, diven)X Pr, drven, (7)P,dim= pf,dinX V.XiXn/120x10-3，(5)where Pt, diven,n is the average friction power losswhere ve is the kinematical viscosity (m2/s) of the(kW) under the condition that the lubricating-oillubricating oil at temperature日; pmx is the maxi-temperature is 50 C and there is no combustion in themum pressure of the combustion gas in the cylindercylinder.(when the rotating speed of the diesel engine is 1 600Letr/ min and gas leakage equivalent is zero (no leak),m=Pr, dive/Pt, dive,(8)its value may reach 3 174.5 kPa);i is the number ofwhere m is the ratio of the average friction power losscylinder, n is the rotating speed of the diesel engineof the diesel engine when the lubricating- oil tempera-(t/ min), Prdive is the friction loss pressure (kPa) intureis日to the average friction power loss of thethe warm-up period, Pf,drive is the friction power lossdiesel engine when the lubricating-oil temperature is(kW) in the warm- up period.50 C. From Fig.3 and expression (8), the value ofWhen the temperature of the lubricating-oil is 50tn, varine Ihrirating oil tempera-C，calculated from expression (4) and (5), the av-tures中国煤化工ig.4.erage friction power loss of the diesel engine Pudive,n .TYHCNMHGrittenasis 35.328 kW.Pi, diven= mX Pi, diven.(9)For the same reason, the friction power losses ofIn the testing of on-the spot no load decelerationJOURNAL OF CHINA ORDNANCE, 2009, Vol.5, No.4ously, we get the relationship between P and2P;diven,nP,= P.anmn(mnts - mzt2)/(t-t2). (17)叫Substitute expression (17) into (15), we get.9P.anvrmn= AEr2(tτ- tz)/(m1 - m2)/(tt2).(18)05540550 7lubriatingoil temperaueCFrom expression (14), we haveFg.4 Efeet of the lbricatingoii temperaturePi= 0Er2/ts- mPradimn.(19)on the m valueSubstitute expression (19) into (16), thenprocess, the special-purpose vehicular diesel enginest。= OE2/(0E12/tq+(1 - m)Pidiran).with same motor hours are used and two sets of data(20)of on: the -spot no load deceleration process at differentFrom expression (20), the general equation folubricating-oil temperature @1， @r are recorded.calculating on the-spot no-load decleration time ofThen, from expression (9)， the correspondingthe diesel engine can be obtainedP.crvnl and P.airven2 can be obtained.tn = AE12/(OEn2/t+(1 - m)Pi,tinemn), (21)If the lubricating-oil temperatures are θ1 andwhere t(s) is the decelerating time from 1 500 r/ min@2, and the times for deceleration from 1 500 r/ minto 500 r/min at the lubricating oil temperature日into 500 r/min are t1 and t2 respectively, then, fromthe experiment of on-the-spot no load decelerationexpression (2), we can getprocess for the specific purpose vehicle with specified0E12= (P,tiven+ Pr)t1,(10)motor hours, m is the value at the lubricaingoilOEn=(Pt, diven+ P)t2.(11)temperature 0, which can be obtained from Fig.4.Because OE12 is a constant and t1 and t2 are3 Conclusionsknown from the experiment data, then P, divea,To sum up the above stated, the method to mod-P, drven can be obtained from expression (9)P, dnas = mPrdiren'(12)ify the lubricaing oil temperature is described as fol-Pl, drvu = mP,driwen(13)lows.1) When the diesel engine of certain model is 0P-where m1 and m2 are the values of m at oil tempera-erated with definite motor hour, the data of on-the-ture @; and日2.spot no load deceleration process should be measuredSubstitute expression (12) and (13) into expres-under two different lubricatingoil temperatures; thesion (10) and (11) respectively, thendeceleration times from 1 500 r/ min to 500 r/ min canOE12 =(mfP,diven.n+ P)ti,(14)be recorded respectively; then find out m1 and m2 ofOEn= (m2Pusien+ P|)tz.(15)the value m ; fnlly, from expression (18), get theSuppose that the motor hour of the diesel enginevalue of P,drive,n.is ascertained and the lubricating oil temperature is 502) When the diesel engine of certain model is oP-C, and decelerating time in the on- the-spot no-loaderated with other motor hours, the deceleration timedeceleration process from 1 500 r/ min to 500 r/ min ist from 1 500 r/ min to 500 r/ min should be measuredtn, then, from expression (2), we getwhen the lubricating-oil temperature in the experi-OEn2= (Piarvmn,n+ P)tpment中国煤化工tion processis日,thenYHc N M H Gubicatingoil andtn= OE12/(Pr,aiven,n+ P).(16)substitute 1into expression (21) to obtain the decel-Combining xpression (14) and (15) simultane-eration time tn from 1 500 r/ min to 500 r/ min when一254-ZHANG Geng-yun, et al. / Inrestigation on the Effect of Lubricating-Oil Temperature on Deceleration Process of the Diesel En-ginethe lubricating-oil temperature in the diesel engine op-Referenceserated with this motor hour.[1] ZHANG Geng yun, HE lai-long. Method for evaluatingAccording to the above stated method, after thethe actual technical condition of the engine[J]. Journal ofnormalizing the measured experiment data of the lu-Academay of Armored Force Engineeing, 2005, (4):68bricating- oil temperature in the range of 30~65 C,- 69. (in Chinese)the minimum value of the deceleration time from 1[2] YAO Zhong-pong. Vehicle coling heat transfer[M].500 r/ min to 500 r/min of the diesel engine is 3.519Bejing: Bejing Institute of Technology Press, 2001. (inChinese)s, the maximum value is 3.601 s. The maximum ab-3] Mohan K V, AridlO, YangSL, et al. A computer sim-solute error of time is 0.082 s and maximum relativeulation of the turbocharged diesel engine as an enhance-error is 2.33%. It is indicated that when the lubri-ment of the vehicle engine coling system simulation[C].cating- oil temperature is varied in the range of 30~65SAE Paper 971804, 1997:1 -17.C, the repeatability of the curve of the deceleration4] Shayler P J, Chitian SJ, Ma T. A model for the inve-process is raised obviously, which can meet the re-tigation of temperature, heat flow and friction character-quirement for predicting the technical condition of theistics during engine warm-up[C] . SAE Paper 931153,diesel engine of the special-purpose vehicle.1993:1588 - 1597.中国煤化工MYHCNMHG