© Strojni{ki vestnik 47(2001)11,662-671 © Journal of Mechanical Engineering 47(2001)11,662-671 ISSN 0039-2480 ISSN 0039-2480 UDK 629.33:629.3.018 UDC 629.33:629.3.018 Pregledni znanstveni ~lanek (1.02) Review scientific paper (1.02) Dolo~itev imenske mo~i motorja s poskusom pospe{evanja vozila Determining an Engine’s WOT Performance from a Vehicle Speed-Up Test Vladimir Medica - Branko Imper - Zoran Imper V prispevku so prikazani rezultati novo razvite metode, potrebnih naprav in postopka za določitev imenske moči motorja s preskušanjem pospeševanja vozila. Preverjanje karakteristike motorja navadno zahteva demontiranje pogonskega motorja iz vozila pred meritvijo na preskusni zavori, ali pa je treba med motor in preostali del pogonskega sistema vozila vgraditi ustrezen dajalnik vrtilnega momenta. V prispevku predstavljena metoda je preprosta in zanesljiva. Vgraditev merilnih naprav je zelo preprosta, za uspešno meritev pa ni treba odstraniti nobenega sestavnega dela vozila. Metoda omogoča, da izmerimo imensko moč motorja s tremi preskusi: ene meritve pri zaviranju in dveh meritev pospeševanja vozila. Pri tem potrebujemo za izračun moči motorja le omejeno število vhodnih - izmerjenih podatkov. © 2001 Strojniški vestnik. Vse pravice pridržane. (Ključne besede: motorji avtomobilski, karakteristike motorjev, modeli matematični, meritve) We present a newly developed method, devices and a procedure for determining an engine’s wide-open throttle (WOT) performance from a vehicle speed-up test. The control of an engine’s performance often requires that the engine is dismantled from the vehicle in order to be able to conduct engine braking test on a bench, or it is necessary to build a torque meter into the drive train of the vehicle. The presented method is very simple and reliable. The mounting of the devices is also very simple, with no need to dismantle any part from the vehicle. The method enables us to derive the WOT performance from three probes, one vehicle deceleration test and two vehicle acceleration tests. The collected test data are processed together with only limited vehicle input data to derive accurate engine-performance figures. © 2001 Journal of Mechanical Engineering. All rights reserved. (Keywords: automotive engines, engine performance, mathematical models, measurements) 0 UVOD Meritev moči motorja navadno opravimo z meritvami na preskuševališču z uporabo ustreznih preskusnih zavor. Motor je treba pred meritvijo odstraniti iz vozila in ga šele potem pritrditi na merilno zavoro. Omenjeni postopek nas omejuje pri izvajanju meritev na motorju v pogostejših oziroma zaradi vzdrževanja zaželenih in predpisanih časovnih korakih. Poznavanje trenutne moči motorja lahko izdatno pomaga pri ugotavljanju stanja motorja. Poleg meritev moči motorja na zavori je mogoče moment motorja ugotoviti tudi z uporabo merilnika momenta v pogonskem sklopu vozila. Ne nazadnje določamo moč motorja tudi na preskuševališču - zavori za vozila z valji Tam seveda lahko izmerimo moč na kolesih vozila. Pri tem postopku se vozilo ne premika, kolesa pa poganjajo valje merilne naprave. Z izmerjenim navorom pri zaviranju in hitrosti vozila lahko izračunamo pogonsko moč vozila. Preskuševališče z valji je po izmerah zelo veliko in zelo drago. 0 INTRODUCTION The performance of an engine can be measured on an engine test bed using an appropriate engine-braking device. To carry out these measurements it is necessary to dismantle the engine from the vehicle. This puts some limits on the practicality of performing these measurements at regular intervals or during regular servicing periods. A knowledge of the engine’s performance could be very useful in evaluating the health of the engine. Instead of measuring an engine’s performance on an engine test bed it is also possible to use a torque meter to determine the engine’s torque in the vehicle drive train, however, this procedure necessitates dismantling the drivetrain parts. There is also the possibility of using a vehicle-brake-test stand with rollers, which is adapted for measuring the driving power on the vehicle’s wheels. The vehicle is fixed to the building’s structure and vehicle’s wheels drive braking rollers. The drive 1 BnnBjfokJ][p)l]Olf|ifrSO | | ^SSfiflMlGC | stran 662 V. Medica - B. Imper - Z. Imper: Dolo~itev imenske mo~i - Determining a WOT Performance Omenjenih merilnih naprav ne srečujemo pogosto v manjših ali celo večjih servisnih delavnicah. V prispevku je opisana nova merilna naprava, ki omogoča določitev imenske moči motorja pri polnem plinu (v nadaljevanju PPP - WOT) s testom pospeševanja vozila. Naprava je zelo preprosta tako po zgradbi kakor tudi pri uporabi. Pri meritvah ni treba izgraditi iz vozila niti motorja, niti katerega koli drugega sestavnega dela vozila. S tem ohranimo tudi jamstvo izdelovalca vozila in izključimo možnosti za okvare delov zaradi nestrokovnega posega. Predstavljena naprava sestoji iz prenosnega osebnega računalnika (laptop, notebook ipd.), naprave z zaznavalom za merejenje vrtilne frekvence koles, električnih kablov in ustreznih računalniških programov V računalnik je treba poprej vnesti osnovne tehnične podatke o vozilu in prenosu. Poleg tega potrebujemo še vodoraven, vsaj 1 km dolg odsek preskusnega cestišča, ki ni obremenjen s prometom. Preskuse lahko opravimo v lepem, suhem vremenu brez vetra. Preskus sestavljajo tri faze: en del s prostim zaustavljanjem vozila in dveh meritev s prostim pospeševanjem vozila (v drugi in tretji prestavi). Programska oprema omogoča pobiranje in obdelavo zbranih podatkov do končnega poročila. Zbrani podatki ostanejo spravljeni v računalniku za kasnejše primerjave oziroma ponovljene preskuse. Pri zasnovi metode je bilo predpostavljeno, da doseže pogonski motor med testom pospeševanja vozila navidezno ustaljeno stanje hitreje kakor se spremeni njegova vrtilna frekvenca. Ta predpostavka je upravičena le pri uporabi sesalnih motorjev. Merilna metoda je le delno uporabna za tlačno polnjene motorje zaradi značilnega “časovnega zaostajanja” teh motorjev Uporabimo jo lahko pogojno tudi za težja gospodarska vozila s tlačno polnjenimi motorji (s turbopolnilnikom na izpušne pline), vendar mora biti preskus pospeševanja znatno daljši, vozilo pa moramo voziti v višjih prestavah. 1 OPIS MATEMATIČNEGA MODELA Povezavo med hitrostjo vozila in vrtilno frekvenco vozila podaja enačba: Do vrtilne frekvence motorja lahko pridemo prek prestavnega razmerja prenosnika moči in vrtilne frekvence koles: Kadar se motor pospešuje pri določeni vrtilni frekvenci koles vozila, potrebujemo za pospeševanje vozila in za premagovanje uporov (aerodinamičnega, hidrodinamičnega kotalnega in drsnega) ustrezno moč: power is calculated from the braking torque and the vehicle’s speed. This type of test stand is usually large and expensive, and these devices are not usually found in small servicing facilities. This paper presents a new device that can determine the wide-open throttle (WOT) performance of an engine from a vehicle speed-up test. This device is very simple and easy to use and the procedure does not involve the dismantling of the engine or the vehicle’s parts. The vehicle’s warranty is preserved and there is no intervening in any vital part of the vehicle’s engine. The device consists of a portable computer (laptop, notebook or similar), a sensing device for the wheel’s rotation, wiring and software. It is neces-sary to input basic vehicle data and drive train parameters. It is also necessary to find an approximately horizontal and straight section of road with a length of 1 km or more. These tests should be made when the traffic is light and when the weather is dry and without wind. The measurement procedure consists of three parts: a single vehicle free-decelerating test and two vehicle accelerating tests (in 2nd and 3rd gears). The software collects and processes the sampled data and then produces a final report. Sampled data are saved for later use or further processing. During the development of the device it was assumed that the engine driving the vehicle during the speed-up test reached the quasi-steady state faster than the engine speed changes. This assump-tion holds for naturally aspirated engines but is of limited use for turbocharged engines due to turbo-charger lag. Nevertheless, the device could be used even for turbocharged engines in long-term vehicle speed-up tests in higher gears and on long straight tracks. 1 MATHEMATICAL MODEL The relation between the vehicle’s speed and the wheel’s rotation frequency is: v = aR = 2%Rn (1). The drive train transmission ratio relates the engine’s rotation frequency to the wheel’s rotation frequency: (2). When the engine accelerates the vehicle at a given wheel-rotation frequency, the engine’s power is needed to accelerate the vehicle and to overcome all friction losses due to the aerodynamic, hydrodynamic, rolling and sliding frictions. Pen (nw )hdt = Pacc (nw )+Pfr (nw (3). stran 663 01-11 firTNEK V. Medica - B. Imper - Z. Imper: Dolo~itev imenske mo~i - Determining a WOT Performance Moč za pospeševanje vozila se porablja za The power for the vehicle’s acceleration premagovanje vozila s potniki oziroma tovorom, za consists of the parts required to increase the povečanje kinetične energije pri premočrtnem gibanju translational kinetic energy of the vehicle (with vozila in tistega dela, ki povečuje kinetično energijo passengers and payload) and the rotational kinetic vrtečih se delov prenosnika moči. energy of the drive train. Pacc (nw mvvv d Jw2 ef w dt mvvv d 2 dt Jw2 dt mvRw2nw dt dt 4J 2 dnw ef w dt Pacc ( nw )=^2nw(mvRw2+Jef) dnw dt (4), (5), (6), (7). Celotni dejanski masni vztrajnostni moment vrtenja prenosnika moči sestavljajo posamezni vztrajnostni momenti pogonskih koles vozila, vrtečih se delov prenosnika in vrtečih se delov pogonskega motorja z vztrajnikom: The drivetrain’s effective moment of inertia is the sum of the vehicle’s wheels’ moments, the drive train’s parts’ moments and the engine with flywheel and coupling, which are all related to the vehicle’s wheels: J ef 2-1 w,i + 2-1 dt,j + J encidt j (8). V večini primerov zgoraj omenjenih treh posameznih masnih vztrajnostnih momentov vnaprej ne poznamo. Ta nepoznani podatek lahko dobimo s pomočjo dveh preskusov pospeševanja vozila v različnih prestavah (v tem primeru v drugi in tretji prestavi). V prikazanem merilnem postopku ni treba analizirati posameznih uporov oziroma izgub in njihovih deležev, ampak le skupno vsoto izgub. Potrebna moč za premagovanje tornih izgub je določena s preskusi ustavljanja (zaviranja) vozila. Vozilo poženemo - v določeni prestavi - do hitrosti, pri kateri dosežemo imensko vrtilno frekvenco motorja. Nato ob sproščeni sklopki pustimo, da se vozilu zaradi tornih izgub zmanjša hitrost. Moč trenja lahko izračunamo z enačbo (3): In most of cases, the moment of inertia of the drivetrain’s components, the wheels and the engine are not known. These unknown values are determined by using two acceleration tests in different gears (in this case 2nd and 3rd). In the presented measurement procedure it is not necessary to analyze various parts of friction losses while only the summary losses are accounted for. The power needed to overcome the friction losses was determined from the vehicle’s deceleration test. The vehicle is driven to a speed that corresponds to the maximum engine rotation frequency, with regard to the transmission ratio. The coupling is then disengaged and the vehicle decelerates only as a result of frictional forces. The friction power is determined from equation (3) to be: Pfr ( nw ) = -Pacc ( nw ) = -4^2nw (mvRw2 + Jef ) dnw dt (9). Iz dosedaj omenjenih enačb lahko povzamemo, da je mogoče določiti moč motorja z uporabo osnovnih podatkov o vozilu in z uporabo časovne spremembe izmerjene vrtilne frekvence koles. Tako izračunano moč motorja, ki temelji na poznavanju vrtilne frekvence koles vozila, lahko preračunamo na vrtilno frekvenco motorja. Iz te vrednosti moči pa lahko določimo tudi moment motorja. Opisani preračun je tudi jedro opisane metode. Iz treh prej omenjenih preskusov lahko določimo naslednje neznanke: - celotno moč trenja vozila, Using this equation we have the possibility to determine the engine’s power from given vehicle parameters and by measuring the rate of the wheel’s rotation frequency with time. The derived engine power, which is related to the rotation frequency of the vehicle’s wheel, is recalculated to the engine’s rotation frequency. From the derived engine power, the engine torque is determined. This is the basis of the device’s operation. From three tests the following unknowns were determined: - vehicle friction power, 1 BnnBjfokJ][p)l]Olf|ifrSO | | ^SsFÜWEIK | stran 664 d V. Medica - B. Imper - Z. Imper: Dolo~itev imenske mo~i - Determining a WOT Performance - dejansko moč motorja, - skupni masni vztrajnostni moment vrtenja pogonskega dela vozila. Pri tem so bili predpostavljeni, oziroma poznani: - podatki o motorju in vozilu (skupaj z nosilnostjo - tovorom oziroma težo potnikov), prehodni režim delovanja motorja se izvede v zelo kratkem času, izkoristek prenosa je poznan, med cesto in pogonskimi kolesi ni zdrsa, prav tako tudi ni zdrsa na sklopki motorja, preskusna steza - cestišče je vodoravno, v okolici ni vetra. Meritev časovnega poteka vrtilne frekvence koles vozila je opravljena z meritvami časa, ki je potreben, da se kolo enkrat zavrti. Od časa odvisne podatke shranimo v ustrezno datoteko. Po meritvah so podatki obdelani glede izračuna neznank in za pripravo končnega poročila. V začetni fazi so izmerjeni podatki pregledani, napačni podatki pa izločeni iz nadaljnje obdelave. Izbrani podatki so potem ustrezno zglajeni (da se izognemo kasnejšim posledicam numeričnega šuma pri določanju sprememb vrtilne frekvence) in nato še računalniško obdelani. Iz časovne vrste podatkov za pretečeni čas enega vrtjaja na merjenem kolesu vozila lahko izračunamo časovni potek prevožene poti vozila v posamezni (od treh) meritvi. Opravljeno pot vozila izračunamo iz enačbe: - engine power, - sum of the engaged moment of inertia. The following assumptions were made: - the engine and vehicle data are known (also the mass of passengers and payload), - the engine transient is very fast, - the drive train efficiency is known, - there is no slip in the engine coupling or between the wheels and the road, - the road is horizontal and there is no strong influence from the wind. The wheel’s rotation frequency was taken from measurements of the time elapsed for one revolution of the wheel. During the tests, these time-related data were sampled to a data file. After the tests the data were processed to determine the un-knowns and the final report was prepared. Data processing of the first sequence data was used to detect and to eliminate false data. The supervised data set is then processed, together with data smoothing to avoid numerical noise amplified by determining the change rate of the rotation fre-quency. From the sampled data for the elapsed times for each revolution of the wheel, the time history of the vehicle’s travel is determined for one of the ve-hicle tests. The traveled distance is calculated from the equation: Lv=^RwNt (10). Vrtilna frekvenca kolesa v poljubnem/-tem vrtljaju je določna z izrazom: Časovno spremembo vrtilne frekvence lahko izračunamo iz enačbe: The wheel’s rotation frequency for the i-th turn is derived from: 1 Dti (11). The rate of rotation frequency change is calculated from the equation: i ) dt Dti+1 + Dti (12). 2 OPIS MERILNE NAPRAVE 2 MEASURING DEVICES Merilni sistem z vsemi sestavnimi deli je shematično prikazan na sliki 1. Zaznavalo za merjenje vrtilne frekvence kolesa sestavlja majhen magnet (pritrjen je na notranji rob platišča kolesa). Za merjeneje vrtilne frekvence pogonskega dizelskega motorja je uporabljen elektromagnetni rele, ta ga pred mehanskimi poškodbami, ki bi lahko nastale zaradi neustrezne medsebojne lege z vzbujevalnim magnetom, varuje okrov iz plastične mase. Medsebojno lego releja in magneta lahko nastavimo z vmesnikom za prilagoditev, s katerim pritrdimo rele na nosilec blažilnika udarcev (sl. 1). The complete measuring set-up is presented in Fig. 1. The revolution sensor consists of a small magnet (cemented to the inner part of the wheel hub) and a small reed-relay (Fig. 2). The reed-relay is from a setup for measuring the revolution frequency of an automotive Diesel engine. A plas-tic housing protects the reed-relay from any dam-age caused by a misalignment of the magnet. To keep the reed-relay in the same postion with re-spect to the magnet an adapter for mounting the reed-relay to the shock-absorber leg was used (Fig. 1). stran 665 01-11 ilTMDDC V. Medica - B. Imper - Z. Imper: Dolo~itev imenske mo~i - Determining a WOT Performance platišče kolesa wheel hub \ magnet zaznavalo sensor D25 vzporedni podatkovni vhod D25 parallel data port vmestnik za prilagoditev lege adaptor blažilnik udarcev shock absorber nosilnik holder pritrdilne^objemke fixators električni kabli wiring računalnik computer Sl. 1. Shema merilne verige in zbiranja podatkov Fig. 1 Measuring set-up for data sampling Sl. 2. Magnet in rele za merjenje vrtilne frekvence kolesa Fig. 2 Magnet and the reed-relay used for sensing the rotation of the wheel Signal, ki prihaja iz releja, se odvaja prek vodnika do vzporednega vhoda osebnega računalnika. Krmilni del vzporednega vhoda vsebuje povezavo prekinitvene zveze (PZ - IRQ) (sl.3) in omogoča samodejno zaznavanje sprememb vhodnih podatkov. Ta signal sporoča informacijo mikroprocesorju o začasni zaustavitvi delovanja in sproži želeno funkcijo. Ko je ta funkcija opravljena, procesor nadaljuje svojo prejšnjo dejavnost. Kadar je signal PZ v vklopljeni legi, je prekinitev dokazana vsakič, ko je potrditveni (POT - ACK) vhodni signal na položajnem vhodu preklopljen iz lege “pravilen“ v lego “napačen“ (ali izklop napetosti). Nastanek in prenos signala k POT vhodu je prikazan na sliki 4. The signal from the reed-relay switches is fed by wiring to the parallel port of the laptop computer. The control part of the parallel port contains an IRQ Enable connection (Fig. 3) to allow the automatic registration of any change in the input data. This signal is a hardware event giving the information to the micropro-cessor to interrupt the operation temporary and acti-vate the desired function. When this function is per-formed, the processor continues with its normal operation. When the IRQ signal is set to the logical “True” (or voltage “ON”), the interrupt is seen each time the ACK input on the status port is switched from logical “True” to logical “False” (or voltage “OFF”). The generation of the signal to the ACK input is shown in Fig. 4. 1 BnnBjfokJ][p)l]Olf|ifrSO | | ^SsFÜWEIK | stran 666 V. Medica - B. Imper - Z. Imper: Dolo~itev imenske mo~i - Determining a WOT Performance Podatkovni vhod Date Port Stanjski vhod Status Port Krmilni vhod Control Port D7 D6 D5 D4 D3 D2 Dl DO Data 7 Data 6 Data 5 Data 4 Data 3 Data 2 Datal DataO D7 D6 D5 D4 D3 D2 Dl DO ^ ~m Busy SCK PE Select Error mo Reserved Reserved D7 D6 D5 D4 D3 D2 Dl DO Reserved Reserved Direction IRQ Enable Select_In INIT Autofeed Strooe Sl. 3. Posnetek vzporednih podatkovnih in krmilnih vhodov na merilni napravi Fig. 3 Parallel ports and port’s controls F N POT /. /ACK 10 IS OZ / CND +5V K Sl. 4. Povezava zaznavala z vzporednim vhodom Fig. 4 Connection of the sensing device to the parallel port Razvita je bila tudi posebna programska oprema, ki omogoča pobiranje podatkov med meritvijo. Čas med dvema zaporednima zaustavitvama, ki ustreza času enega vrtljaja kolesa vozila se tudi vnaša v podatkovno bazo. Raven natančnosti merjenja tega časa ustreza eni mikrosekundi. Del programa za zbiranje podatkov je bil uporabljen za kalibracijo merilnika hitrosti vozila. Ustrezni program je omogočil tudi prikaz natančne hitrosti vozila in vrtilne frekvence motorja v vrt/min na zaslonu računalnika. Omenjena podatka sta namenjena za vodenje poteka meritve in preprečevanje morebitne prekoračitve vrtilne frekvence motorja med meritvijo. Računalniški program za obdelavo izmerjenih podatkov je razdeljen na prvi del, ki preverja in izloča prave in napačne podatke. Napačni podatki nastanejo zaradi neželenega nihanja stikala releja, ali pa merilni podatek včasih tudi izostane. Če je pri meritvi veliko napak, se vsi podatki zavrnejo in meritev je treba ponoviti. Primer vrste popačenih podatkov lahko vidimo na sliki 5. Preverjeni podatki so potem urejeni, zglajeni in ob koncu prirejeni za končno poročilo o izračunani moči motorja. Program omogoča tudi prikaz vseh podatkov, njihovo obdelavo in prikaz končne oblike To enable the data sampling during the measurement we developed software. The time elapsed between two successive interrupts, which corresponds to the time of one full revolution of the wheel is written to the data file. The precision of the measurement was at the microsecond level. One part of the data-sampling software was used to calibrate the vehicle’s speed indicator. The software indicates the accurate vehicle speed and engine revolution frequency in rpm on the laptop screen. These data are used to control the test procedure and to avoid engine overspeed during the tests. The software for sampled-data processing contains the first part for data supervision to detect and to eliminate false data. False data are the result of erroneous reed-relay switch vibrations or due to missing data. If there are a lot of errors, the sampled data are discarded and a new measurement has to be performed. Examples of erroneous data are presented in Fig. 5. The supervised data set is then processed and smoothed to give a final report on the engine’s performance. The software enables sampled-data visualization, processing and presentation of the final stran 667 01-11 ilTMDDC V. Medica - B. Imper - Z. Imper: Dolo~itev imenske mo~i - Determining a WOT Performance 140,203294 140,743865 141,441164 4,010286 138,052741 142,701352 143,513778 73,840134 73,852941 73,863457 148,088236 74,081291 74,175382 74,317489 Sl. 5. Primer vrste napačnih podatkov; levi stolpec - vzrok je v nihanju stikala, desni stolpec - vzrok je v nesklenjenem stikalu Fig. 5. Examples of erroneous data. Left - due to the switch vibrations, Right - due to missing the switch closure končnega poročila. Matematični model, ki je bil prikazan v drugem poglavju je uporabljen v opisanem računalniškem programu skupaj z nadzorom in obdelavo podatkov. Celoten merilni sistem je bil pred uporabo skrbno preverjen. Preverjen in določen je bil pravilen razmik med magnetom in zaznavalom. Ugotovljeni razmik naj ne bi presegel 10 mm. Signal zaznavala, ki je bil priključen na vzporedni vhod, in program za zbiranje podatkov sta bila preverjena z generatorjem, ki je dajal pravokotne signale z nastavljivimi frekvencami signala. Signal je bil nato ojačen in posredovan tuljavi, ki je vklopila rele (sl.6). To preverjanje je bilo namenjeno določitvi uporabnega področja delovnih frekvenc uporabljenega releja. Odzivnost releja se je izkazala za ustrezno; delovne frekvence so močno presegle pričakovane vrtilne frekvence koles vozila. report. The mathematical model presented in section 2 is implemented into the software, together with the data supervision and the data smoothing procedures. The complete measuring system was carefully tested before use. This testing was performed to determine the allowable distance between the magnet and the sensing device, which was found to be up to 10 mm. The sensing device, connected to the parallel port and the software for data sampling, was tested using a rectangular signal generator with a controllable signal frequency. The signal was amplified and applied to the wire coil activating the reed-relay (Fig. 6). This control was performed to determine the applicable reed-relay frequency domain, which was found to be much higher than the expected wheel rotation frequency. generator signala signal generator _TL elektromagnet V coil i&r/lrele R R OZ / GND Sl. 6. Shema preverjanja merilne opreme Fig. 6 Test setup for the measuring device 3 PRIMERI MERITEV MOČI MOTORJA Vzorčno preskušanje metode je bilo v praksi preverjeno na različnih osebnih avtomobilih in opravljeno na vzletni letalski stezi z dolžino 1800 m. Meritve so bile opravljene s tridelnim preskusnim postopkom. V prvem delu se je vozilo ob izklopu pogonskega agregata prosto zaustavljalo; ta del je bil uporabljen za določitev voznih uporov vozila. V drugem 3 MEASUREMENT EXAMPLES Sample measurements on various passenger cars were performed at a local airport runway with a length of 1800 m. Measurements were per-formed in three succesive tests. The first test was performed using free vehicle deceleration to determine the vehicle’s driving resistance. The second and third tests were performed using the vehicle’s 1 BnnBjfokJ][p)l]Olf|ifrSO | | ^SSfiflMlGC | stran 668 V. Medica - B. Imper - Z. Imper: Dolo~itev imenske mo~i - Determining a WOT Performance in tretjem delu je bilo vozilo pospešeno v drugi oziroma tretji prestavi. Na slikah 7, 8, in 9 so prikazani rezultati meritev na treh različnih osebnih avtomobilih. acceleration with an engaged engine in 2nd and 3rd gears. Three examples of the results are presented in Fig. 7, 8 and 9. ^ moment motor engine torque a ^ ------ «V moč motorja ~ ™«inpnnwpr ¦< - *1fW vehicle acceleration power Lmr^trmiisi vrwilsi H vehicle friction — i 0 500 1000 1500 2000 2500 3000 3500 4 000 4500 5000 5500 5000 6SO0 7000 Vrtilna frekvenca, min-1 Engine speed, rpm Sl. 7. Rezultati meritev karakteristik motorja PPP na osebnem vozilu Citroen BX 1.6 Fig. 7. WOT performance for a Citroen BX 1.6 100-1 85^ 9fr 85^ 8fr 75^ 7CH 65^ 60-55-i 50^ 45-40: 3& 30 ¦: 25-20^ 15^ 5: oo moment moto engine torq! >rja ue ^ k, \ moč motorja engine power m oč med pospeševanjem hicle acceleration power V " m ottrenja vozila vel vehicle friction power —i—t- i I ) 500 1000 1500 2000 2500 3000 3500 4000 4,500 5000 5500 6000 6500 7C Vrtilna frekvenca motorja, min-1 Engine speed, rpm Sl. 8 Rezultati določanja PPP karakteristike motorja na osebnem avtomobilu Renault Clio 1.2 Fig. 8 WOT performance for a Renault Clio 1.2 4 SKLEP V prispevku je prikazana cenena in praktična naprava za merjenje karakteristike pogonskega motorja vozila PPP. Naprava omogoča hitro določanje moči motorja brez odstranitve katerega koli sestavnega dela v pogonskem sklopu vozila. Takšen postopek določanja moči je cenen in primeren tudi za manjše servisne delavnice; pri tem ni prizadeta nedotakljivost pogonskega sklopa ali njegovih delov in s tem ogrožena veljavnost jamstva izdelovalca vozila. Za izvedbo meritev moči je, v nasprotju z obširno in zelo zahtevno in drago merilno opremo, potrebna le skromna in cenena merilna oprema. 4 CONCLUSIONS An inexpensive and easy-to-use device for determining a vehicle’s engine’s WOT performance is presented. The device enables fast measurements of engine performance without any dismantling or disconnecting of the engine or any of the drive train parts. This enables cheap and easy tests for small servicing enterprises without breaking any vehicle warranty condi-tions and without investing in expensive mea-suring equipment. stran 669 01-11 ilTMDDC V. Medica - B. Imper - Z. Imper: Dolo~itev imenske mo~i - Determining a WOT Performance 1Mh mom engine torque ------ \ ™nH „.„<—:- • ower _ "^ ----- \ \_ moč med pospeševanjem """"moč trenja vozila vehicle accelerate ™ ¦ ^*~ vehicle friction power, (^ T^T-,,[,,, j 0 500 1000 1500 2000 2 500 3000 3500 4000 4500 5000 5500 6000 6500 7000 Vrtilna frekvenca motorja, min-1 Engine speed, rpm Sl. 9. Rezultati določanja PPP karakteristike motorja na osebnem avtomobilu Opel Kadett 1.6D Fig. 9 WOT performance for a Opel Kadett 1.6D Predstavljena metoda in postopek zahtevata osebni prenosni računalnik z ustrezno programsko opremo, zaznavalo za določanje vrtilne frekvence koles in ožičenje. Z opisanim sistemom je mogoče zelo natančno določiti karakteristiko moči sesalnega motorja, ki “opravi” prehod na nov režim delovanja v sorazmerno kratkem času. The presented device consists of a laptop computer, software, a sensor for wheel rotation and wiring. This measurement setup determines very ac-curate performance figures for naturally aspirated engines due to the very fast transient response of the vehicle’s transient. This method is, under certain conditions, also applicable to turbocharged engines. 5 SIMBOLI 5 SYMBOLS prestavno razmerje prenosnika moči i transmission ratio masni vztrajnostni moment J kg-m2 moment of inertia L m travelled distance masa m kg mass vrtilna frekvenca n s-1 rotation frequency število vrtljajev kolesa N number of wheel revolutions moč P W power polmer R m radius čas t s time hitrost vožnje po ravnem v m/s linear velocity časovni korak Dt s elapsed time step izkoristek h efficiency kotna hitrost w s-1 angular velocity Indeksi Indices pospeševanje acc acceleration prenosnik moči dt drivetrain upor pri trenju fr friction, resistance dejanski ef effective motor en engine motor z vztrajnikom in sklopko enc engine with flywheel and coupling indeks i index indeks j index celoten t total vozilo v vehicle kolo w wheel 1 Sg"ins(5)[J)[M]! ma stran 670 V. Medica - B. Imper - Z. Imper: Dolo~itev imenske mo~i - Determining a WOT Performance [1] [2] [3] [4] [5] 6 LITERATURA 6 REFERENCES Imper, B. (2000) Project of the device for determination of the engine WOT performance (in Croatian), BSc degree thesis, Faculty of Engineering, University of Rijeka. Imper, Z. (2000) Project of the changes in the intake system of the spark ignition engine (in Croatian), BSc degree thesis, Faculty of Engineering, University of Rijeka. Heywood, J. B. (1988) Internal combustion engine fundamentals, McGraw Hill Book Co., ISBN 0-07-028637-X. Anderson, P. H. (1996) Use of a PC printer port for control and data acquisition. Malmstadt, H. V. , C.G. Enke (1969) Digital electronics for scientists, W. A. Benjamin, Inc. Naslov avtorjev: prof. dr. Vladimir Medica Branko Imper Zoran Imper Tehnički fakultet Sveučilište u Rijeci Vukovarska 58 HR-51000 RIJEKA Authors’ Address: Prof. Dr. Vladimir Medica Branko Imper Zoran Imper Faculty of Engineering University of Rijeka Vukovarska 58 HR-51000 RIJEKA, Croatia Prejeto: Received: 19.10.2001 Sprejeto: Accepted: 7.12.2001 stran 671 01-11 firTNEK