The accelerated laboratory test of biodegradable fluid type ertto

Transcription

1 Vol. 56, 00, No. : 8 5 Res. Agr. Eg. The accelerated laboratory test of biodegradable fluid type ertto Z. Tkáč, R. Majda, Š. Drabat, J. Jabloický, R. Abrahám, P. Cvíčela Departmet of Trasport ad Hadlig, Faculty of Egieerig, Slovak Agriculture Uiversity i Nitra, Nitra, Slovak Republic Abstract Tkáč Z., Majda R., Drabat Š., Jabloický J., Abrahám R., Cvíčela P., 00. The accelerated laboratory test of biodegradable fluid type ertto. Res. Agr. Eg., 56: 8 5. The accelerated laboratory tests ca evaluate the properties of ew biodegradable fluids uder relatively short time. These test results are the groud for the cotiuity of the tests uder operatio coditios i machie. The paper presets the test of ew biodegradable hydraulic fluid type Evirometally resposible tractor trasmissio oil by desiged special test device. The test evaluatio was realized by techical state of cocrete hydrostatic pump UD 5 which is used i tractors Zetor Forterra. This pump was loaded by cyclic pressure loadig durig the test with tested fluid. The evaluated parameter was flow efficiecy of hydrostatic pump which reached the value 7.3% after the test. The reached value hits a high quality of the tested fluid (the limit value per stadard is the flow efficiecy decrease 0%). Keywords: hydrostatic pump; cyclic pressure loadig; testig device; flow characteristics The hydraulic fluid has to provide various additioal fuctios besides its mai fuctio to trasmit the pressure eergy (Kučera, Rousek 005). The most commo fuctios result from activities of hydrostatic circuits. These fuctios relate to the lubricatio of the movig compoets, the rust protectio etc. (Mihalčová 004). The chemical ad oxidative stability is coessetial as the properties metioed above because of their ifluece o ecoomical operatio of fluid ad all system. At preset, the most perspective productio is aimed at the fluids made from the reewable atural resources. The fossil resources for the fluid productio are limited ad also the eviromet protectio is a very importat factor (Wager et al. 00). The biodegradable fluids are the solutio of both aspects. As was metioed above, the hydraulic fluids have to meet challegig criteria. Just, the high degree of biodegradatio differetiates these biodegradable fluids from fluids made of the crude oil. The evaluatio of properties of ewly desiged biodegradable fluids is based o various test methods to be progressed. This paper is aimed at the evaluatio of a ew biodegradable fluid made by the Slovaft compay o the groud of accelerated laboratory test. Material ad Methods The test descriptio The fudametal criterio for fluid evaluatio i the case of accelerated test is the fluid ifluece o the durability of cocrete type of hydrostatic pump (UD 5). Therefore, the fluid is evaluated o the Supported by the Scietific Grat Agecy of the Miistry of Educatio of the Slovak Republic ad Slovak Academy of Scieces VEGA, Grat No. /046/09. 8

2 Res. Agr. Eg. Vol. 56, 00, No. : 8 5 Fig.. The hydrostatic pump type UD 5 coected to testig device groud of techical state of the parts (hydrostatic pump) which is placed i every hydraulic circuits of every machie. The hydrostatic pump is most loaded by fluid uder operatio coditios. Durig the test (test takes the time of 0 6 cycles) the hydrostatic pump is loaded by cyclic pressure loadig which simulates the hydraulic circuit load uder operatig coditios. The techical state evaluatio of hydrostatic pump accordig to the flow characteristic ad calculatio of the flow efficiecy are doe by fluid evaluatio, too. The flow characteristic Q = f (p) depeds o iteral leakages of hydrostatic pump. The ew hydrostatic pump has the miimal iteral leakages ad durig the operatio it icreases. The chage of iteral leakages affects the chage of flow efficiecy ad flow characteristic. The flow efficiecy is calculated o the groud of measured flow uder omial parameters of hydrostatic pump, i.e. pressure of 0 MPa ad rotatio speed of,500 revolutios per mi. The maximal flow efficiecy decrease is limited by the value of 0% (STN 987). The flow characteristics were measured durig the test (0 6 cycles of pressure loadig) i regular itervals every 50,000 cycles. Every measuremet was repeated o the groud of the statistical calculatios. The characteristics are result of regressio aalysis doe by the MS Excel software. Fig.. Testig device for realizatio of laboratory durability test of hydrostatic pumps (Tkáč et al. 008): M electric motor, rpm sesor, HG tested hydrostatic pump, TV two stage pressure relief valve, TV two stage sequece valve for adjust omial pressure i the outlet of hydrostatic pump, p pressure gauge of pressure i the ilet, p pressure gauge of pressure i the outlet, K spherical plug valve, PR gear box, OB cotrol block, T tak, RV tree-positios, four-port slide valve with closed ceter which is operated electro-hydraulically, CH, CH, CH 3 coolers, V, V, V 3 fas, HG hydrostatic pump for cooler, t temperature sesor for tak, R thermostatic regulator which cotrol switchig o of coolig fas 9

3 Vol. 56, 00, No. : 8 5 Res. Agr. Eg. The descriptio of hydrostatic pump of UD 5 type The hydrostatic pump of UD 5 type (Fig. ) is oe-directio hydraulic gear pump made by the Jihostroj Aero Techology ad Hydraulics compay. This gear pump is equipped with the hydraulic balacig of axial clearace, which is doe by sealig i the ed face bearigs. It is used i smaller ad medium agriculture ad costructio machies. The UD hydrostatic pumps types are used i Zetor tractors ad i Tatra commercial vehicles (Jihostroj, Ltd., 007; Tkáč et al. 008). The descriptio of hydraulic fluid type ERTTO The hydraulic fluid ERTTO (Evirometally resposible tractor trasmissio oil) is biodegradable tractor oil. The oil is made of atural vegetable oil ad special additives. The oil is aimed to use i gearbox ad hydraulic circuit of agricultural ad costructio machies. Primary biodegradatio per CEC L-33-A-93 is 90% withi 8 days, ad by OECD 30 B test method it is 65%. The value of kiematic viscosity uder 40 C is mm /s; viscosity idex is 3; pour poit is 39 C (Slovaft, Ltd., 008). The test device desiged for tests of hydrostatic fluids The desiged test device (Fig. shows the schema) eables to test the hydraulic fluids o the groud of 5 evaluatio of techical state of hydrostatic pump which is tested with the fluid. I this case, the load of hydrostatic pump ad fluid is realized by cyclic pressure loadig uder pressure chage from p = 0 MPa to omial pressure p = 0 MPa, frequecy f =. Hz ad velocity of pressure icrease v = 340 MPa/s. The cyclic pressure loadig is techically realized by cyclic chage of slide valve positio RV. This valve chages its state from cetral positio to left positio. The omial pressure o the outlet of pump is limited by pressure sequece valve TV. The test device was desiged accordig to the works published by Drabat et al. (005) ad Petraský et al. (004). The test device burdes hydrostatic pump by the cyclic pressure. The characteristic of cyclic pressure loadig is show i Fig. 3 (Radhakrisha 003). The device dedicated to flow characteristic measuremet The Fig. 4 shows the schema of desiged device dedicated to measuremet of flow characteristic. Before every measuremet the hydrostatic pump (marked as HG ), which is used durig the test, was dismouted from the test device (Fig. ) ad mouted to device for flow characteristic measuremet (Fig. 4). The circuit with the tak T serves for drive of measured hydrostatic pump HG. The pressure sesor (s.p.), flow sesor (s.q.) ad temperature sesor (s.t.) are coected to the output of hydrostatic pump which is placed i secod circuit with tak T. Durig the measuremet the pressure sequece valve adjusts the pressure i rage from p = 0 MPa to omial p = 0 MPa. Durig the cotiuous pressure chage the flow is measured for characteristic Q = f (p). All parameters are recorded by digital device HMG 00. pressure p (MPa) time t (s) Fig. 3. The characteristic of cyclic pressure loadig: p pressure, t time (Radhakrisha 003) The cout of flow characteristic measuremets repetitio The measuremet chai is oscillatig durig the flow characteristic measuremet. I cosequece, the flow value must be processed from measured values. The required cout of flow values ca be stated o the groud of the calculatio per equatio as follows (Rataj 003): 0

4 Res. Agr. Eg. Vol. 56, 00, No. : 8 5 Vk t () V k variatio coefficiet t β critical value estimated o the basis of probability δ maximum admissible error The statistical processig of measured values The arithmetical average was used for calculatio of average value from measured values x : x N x i i N file size i sigature i of variable value i file x i value of variable i file () Flow coversio by reaso of rotatio speed chage I the test device the three-phase electromotor was used which caot provide costat rotatio speed durig the measuremet. Therefore, the actual rotatio speed was measured by speedometer. For costructio of flow characteristic the flow values after coversio o,500 per mi were used. Seeig that, the volume losses are costat uder less rotatio speed chage (,500 ± 75) per mi the flow efficiecy η pr is costat, too. Therefore, we ca write equatio (Varchola 99): η pr = η pr Q V G Q Q Q V G Q Q after modificatio: (3) Fig. 4. Testig device for measuremet of flow characteristics of hydrostatic pumps (Tkáč et al. 008): M electric motor,, rpm sesors, HG variable axial pisto pump, TV, TV two stage pressure relief valves, K spherical plug valve, HM agled pisto motor, HG tested hydrostatic pump, TV 3 two stage sequece valve for pressure adjustmet, s.p. pressure sesor, s.q. flow rate sesor, s.t. temperature sesor, R thermostatic regulators of oil temperature, T, T taks, p, p, p 3, p 4 pressure gauges

5 Vol. 56, 00, No. : 8 5 Res. Agr. Eg. Q flow measured at the rotatio speed (dm 3 ) Q flow at required rotatio speed (dm 3 /mi) V G geometric volume of hydrostatic pump (dm 3 /mi) η pr flow efficiecy durig measuremet of flow η pr flow efficiecy at required rotatio speed The calculatio of flow efficiecy decrease The stadard STN 987 dictates the way for the evaluatio of the test. The fluid must be evaluated per flow efficiecy decrease of hydrostatic pump as follows: pr0 prm pr 00 pr0 (%) (4) Δη pr the flow efficiecy decrease (%) η pr0 the flow efficiecy 0 cycles η prm the flow efficiecy after 0 6 cycles The, the flow efficiecy is expressed by equatio: pr Q 00 V G (%) (5) Q coversed flow (dm 3 /mi) V G geometrical volume of hydrostatic pump (dm 3 ) omial rotatio speed of hydrostatic pump (/mi) Results ad Discussio The required cout of measuremet repetitio The cout of repetitio was calculated per Eq. () o the groud of variatio coefficiet V k =.3%. The calculatio was based o maximul error allowed δ = 4% ad o critical value t β =.8 which was stated o the basis of likelihood 90%. This value is adequate for experimets coected to machie costructio (Rataj 003). The calculated value = 43 expresses the cout of measuremet repetitios. The measuremet system composes of digital record device HMG 00 ad sesors. The system records measured values i time iterval 0.05 s. Therefore, the cout of values ( = 43), which was calculated per Eq. () we obtai from 4 measuremets of flow characteristic. The flow characteristics of hydrostatic pump from the test of fluid type ERTTO The characteristics (Fig. 5) were obtaied by regressio aalysis ad regressio model of third degree polyomial type. Fig. 6 shows the values obtaied i the flow measuremets. The two most importat measuremets, 39 ERTTO, Q = f(δp), =,500 /mi 38 Flow Q (dm 3 /mi) Pressure p (MPa) 50, cycles 0 cycles 500, cycles,000,000 cycles 750, cycles Fig. 5. Flow characteristics from the test of fluid type ERTTO

6 Res. Agr. Eg. Vol. 56, 00, No. : ERTTO, Q = f(δp), =,500 /mi Flow Q (dm 3 / mi) Fig. 6. Measured values for flow characteristics Pressure p (MPa) 0 cycles,000,000 cycles amely 0 cycles ad 0 6 cycles, were selected. The flow characteristics were made with MS Excel by regressio aalysis with the use of polyomial model of three degree. The average flow value uder 0 6 cycles Q m = dm 3 /mi (the ed of the test) is arithmetical average of 43 measured flow values (Table ) ad was calculated per Eq. (). The average values of measured flows The average value uder 0 cycles Q 0 = dm 3 per mi (the start of the test) is arithmetical average of 43 measured flow values (Table ) ad was calculated per Eq. (). The calculatio of flow efficiecy decrease The flow efficiecy decrease Δη pr = 7.3% was calculated per Eq. (4) o the groud of flow efficiecy uder 0 cycles η pr0 = 97.4% ad flow efficiecy after 0 6 cycles η prm = 90.5% calculated per Eq. (5). Table. Measured values of flow uder pressure 0 MPa start of the test No. Flow Q 0 (dm 3 /mi) No. Flow Q 0 (dm 3 /mi) No. Flow Q 0 (dm 3 /mi) No. Flow Q 0 (dm 3 /mi)

7 Vol. 56, 00, No. : 8 5 Res. Agr. Eg. Table. Measured values of flow uder pressure 0 MPa ed of the test No. Flow Q m (dm 3 /mi) No. Flow Q m (dm 3 /mi) No. Flow Q m (dm 3 /mi) No. Flow Q m (dm 3 /mi) Coclusio The biodegradable fluid type ERTTO was tested with special test device usig hydrostatic pump type UD 5 of a cocrete type of agricultural tractor, Zetor Forterra. The test device was desiged i order to test fluid loads i the hydrostatic pump by cyclic pressure loadig. The cyclic pressure loadig has the form as give i Fig. 3 ad it fulfils limit stated i the stadard STN 987. O the groud of this stadard all the test was evaluated. The flow efficiecy decrease reaches the value Δη pr = 7.3%. The stadard reports maximal flow efficiecy decrease as 0%. The value of tested fluid is thus greatly below this value. O the groud of the test results we ca say that the tested biodegradable fluid is a high quality product. The comparative results were published i papers of Petraský et al. (995). The object of his research was gear pump PZ--8-KS- used i tractors ZTS UR II i that time. I the test accordig the same stadard STN 987 the ruig-up fiished after 600,000 cycles. Drabat et al. (005) evaluated the techical durability of gear pump type UN 0L. used i tractors ZTS UR IV. This test was characterized by flow efficiecy decrease Δη pr = 3.77% after 0 6 cycles. The test was realized i cooperatio with compay Slovaft, Ltd., a member of MOL (Hugary s oil compay) group. The petroleum compay will use the results i this research i the area of applicatio of ew biodegradable hydraulic fluids. I the ear future the last test of this fluid uder operatio coditios i hydraulic circuit of tractor Zetor Forterra will be carried out. R e f e r e c e s Drabat Š., Tkáč Z., Žikla A., 005. Laboratory test of techical life of the tractor hydrogeerator with biodegradable fluid eko uiverzal. Acta hydraulica et peumatica, : Jihostroj, Ltd., 008. Katalog produktů (Product catalogue). Available at: (accessed Jue 4, 009) Kučera M., Rousek M., 005. Evirometally compatible hydraulic oils for hydraulic compoets of mobile machiery. I: Iteratioal Sciece Coferece Hydraulic Mechaisms of Vehicles, October, 005. Dudice: Mihalčová J., 004. Global evaluatio of quality oils by selected aalytical methods. I: Proceedigs Trasactios of the Uiversities of Košice Research reports from the Uiversities of Košice, Jauary 5 7, 004. Košice: Petraský I., Drabat Š., Tkáč Z., Žikla A., Bolla M., Kleiedler P., 004. Skúšobé stavy pre životosté skúšky hydrostatických prevodíkov (Test Devices for Durability Tests of Hydrostatic Drives). Nitra, Slovak Agricultural Uiversity i Nitra. Petraský I., Drabat Š., Zgebura Š., Moravčík J., 995. Skúšky traktorových hydrogeerátorov s biologicky odbúrateľou kvapaliou (Tests of Tractor Hydrostatic Pumps with Biodegradable Fluid). Agriculture, : Radhakrisha M., 003. Hydraulic Fluids. New York, America Society of Mechaical Egieers: Rataj V., 003. Tvorba vedeckého a odborého textu (The Creatio of Scietific ad Techical Text). Nitra, Slovak Agricultural Uiversity i Nitra: 4. Slovaft, Ltd., 008. Katalog produktů (Product catalogue). Available at: 4

8 Res. Agr. Eg. Vol. 56, 00, No. : 8 5 obchodi_parteri/vyrobky/maziva_a_autochemikalie/ automobilove_maziva/uiverzale_traktorove_oleje/ mol_traktol_h_ultra_traktorov hydraulick a_prevodov olej_/ (accessed Jue, 009) STN 987 Hydrostatické zubové geerátory a motory (Hydrostatic Gear Pumps ad Motors). Bratislava, SÚTN. Tkáč Z., Drabat Š., Majda R., Cvíčela P., 008. Testig stads for laboratory tests of hydrostatic pump of agricul- tural machiery. Research i Agricultural Egieerig, 54: Wager H., Luther R., Mag T., 00. Lubricat base fluids based o reewable raw materials. Applied Catalysis A: Geeral, : Varchola M. 99. Hydrostatické čerpadlá (Hydrostatic Pumps). d Ed. Bratislava, Sloveská techická uiverzita v Bratislavě: 9. Received for publicatio Jue 9, 009 Accepted after correctios October 4, 009 Correspodig author: Ig. Radoslav Majda, Slovak Agriculture Uiversity i Nitra, Faculty of Egieerig, Departmet of Trasport ad Hadlig, Tr. A. Hliku, Nitra , Slovak Republic phoe: , fax: , radoslav.majda@gmail.com 5