POWERSHIFT DIFFERENTIAL TRANSMISSION WITH THREE FLOWS OF POWER

Transcription

1 /v POWERSHIFT DIFFERENTIL TRNSMISSION WITH THREE FLOWS OF POWER JROSLV PITOŇÁK, MIROSLV GLBVÝ, JURJ PRODJ University of Žilina, Department of Design and Mechanical Elements, Univerzitná 1, Žilina, Slovakia ZHRNUTIE V súčasnej dobe nachádzajú v stavbe vozidiel najväčšie uplatnenie koncepčne jednoduché hriadeľové a planétové prevodovky. V týchto prevodovkách je na zaradenie konkrétneho prevodového stupňa potrebné zopnúť, resp. rozopnúť jeden alebo viacero radiacich prvkov a konkrétne ozubené súkolesie sa často využíva len pri konkrétnom prevodovom stupni. Naproti tomu diferenciálne prevodovky svojím usporiadaním umožňujú dosiahnuť delenie toku výkonu do viacerých vetiev a ponúkajú tak možnosť pri nižšom počte ozubených záberov a radiacich prvkov dosiahnuť vyšší počet prevodových stupňov. Ich základom je jednoduché planétové súkolesie, ktoré pri konkrétnych prevodových stupňoch pracuje vo funkcii prevodu, pri iných prevodových stupňoch pracuje vo funkcii diferenciálu. Tento princíp je základom prevodovky opisovanej trojtokovej diferenciálnej prevodovky s radením pod zaťažením. KĽÚČOVÉ SLOVÁ: TROJTOKOVÁ DIFERENCIÁLN PREVODOVK, TRNSMISI, POHON, SIMDRIVELINE, SIMULÁCIE PREVODOVIEK BSTRCT Currently simple shaft and planetary transmissions are the most commonly used types of transmissions due to their concept simplicity. In these transmissions it is necessary to engage and disengage one or more control components in order to select the given speed gear, whereby a single gear pair is often used in one speed gear only. On the other hand, differential transmissions enable a power split to more flows due to its design, so they offer a higher number of gear speeds for a lower number of gears and control components. The base of the transmission is a planetary set, which works as a gear at several gear speeds, whilst at other gear speeds as a differential. This principle is the basis of the described powershift differential transmission with three flows of power. KEYWORDS: DIFFERENTIL TRNSMISSION WITH THREE FLOWS OF POWER, TRNSMISSION, DRIVE, SIMDRIVELINE, TRNSMISSION SIMULTIONS 1. INTRODUCTION The basic concept of the powershift differential transmission with three flows of power was described in [1, 2], where the main idea and principle of a transmission based on connection of countershaft gears with a differential were also further explained. The cited contributions also described in detail a methodology for obtaining the main parameters and verification of solution correctness achieved with the aid of simulations. The following contribution deals with the specific designed transmission as a logical unit (Figure 1), inquires into the basic parameters important for power transmission and studies the behavior of the transmission in a lorry drive. 2. TRNSMISSION WORKING PRINCIPLE The described powershift transmission is based on a differential with four shafts combined planetary mechanism, which consists of two simple planetary gears (Figure 1). This differential has three input shafts and one output shaft. By inserting several countershaft gears before the differential it is possible to create a configuration in which the power can be split into three flows and subsequently merged in this four-shaft-differential. This gives rise to the configuration of three flows of power [3, 4]. Situated after the four-shaft-differential is the additional group. This consists of shaft clutch with powershift functioned JROSLV PITOŇÁK, MIROSLV GLBVÝ, JURJ PRODJ MECC PGE 1

2 with the help of clutches S 4 and S 5, which enables two gear speeds. The additional group multiplies the number of gear speeds, so the result is fourteen gear speeds [3, 5]. 3. TRNSMISSION REQUIREMENTS The designed differential transmission is suitable for application in the drives of lorries, fire engines, commercial vehicles, military vehicles, industrial machines and generally in machines or vehicles that require high number of powershift gear speeds and that move on hardened or soft surfaces. Its main design includes a definition of the minimum and maximum transmission ratios and the option of all other transmission ratios. To specify the given transmission ratios an understanding is required of the direct requirements for the vehicle, and in particular its operating conditions [3, 4, 5]. ccording to the known definitions it is possible to set the minimum and maximum transmission ratio, but it is also necessary to pay regard to final drives. Between these two boundary numbers the correct differentiation of transmission ratios according to the chosen series is needed. With respect to the cooperation between engine and transmission, and an additional transmission the differentiation between adjacent transmission ratios φ has to be approximately the same [4, 5]. For the mentioned transmission the following equations have been defined [3], whereby all the designations for equation parameters and transmission components are the same as shown in Figure 2 (R 2 = Q 1 ): P1 Q1 V1 ( 1 uv1) ωr1 ω ω u = (1) P 2 Q2 V 2 ( 1 uv 2) ω R2 ω ω u = (2) (3) Q2 P 2 3 (4) P1 1 2 (5) (6) R1 X P The overall transmission ratio i X between input and output shaft is defined: = ω ω = ( 1 uv2) ( 1 uv1) i1 i2 i3 ip ( 1 u ) i i u i ( i u i ) i X X V V1 1 3 V 2 2 If the transmission ratio of first gear is designated i X1, the ratio of second gear is i X2 and the ratio of the n th gear is i Xn, we can set the gear differentiation φ [3,4,5] between two adjacent gear steps: (7) ix( n- 1 ) ( n- 1 ) = ixn φ (8) Gear differentiation is a very important parameter because in many cases (e.g. in lorry transmissions) it is desirable to have approximately the same gear differentiation between all adjacent transmission ratios. So we can talk about an approximately constant-gear-differentiation-condition [4, 5]. However, in car transmissions the gear differentiation varies according to a certain relationship, so a progressive differentiation is required. 4. BSIC TRNSMISSION PRMETERS ND CHIEVED TRNSMISSION PRMETERS The transmission consists of countershaft gears, a four-shaftdifferential and addition group schematically depicted and designated in Figure 2. The transmission ratios of countershaft gears i 1, i 2, i 3, internal transmission ratios of both planetary sets in the differential uv1, uv2 and additional-gears-ratios i P1 a i P2 are: i 1 = 2; i 2 = 3; i 3 = 3,2 u v1 = 3; u v2 = 2,4 i P1 = 1; i P2 = 0,27 The individual clutches and brakes are engaged and disengaged in order to shift the gear speeds exactly according to Table 1. ll the transmission ratios are set out in Table 1 and Figure 3. The gear designated 0 is intended for starting a loaded vehicle in difficult conditions on a soft surface. The other twelve gear speeds can be used in standard operating conditions. 5. KINEMTIC ND MOMENT CONDITIONS OF INDIVIDUL TRNSMISSION COMPONENTS For kinematic and moment analysis calculation of all angular velocities, torque moments for all gear speeds are needed. The methodology from [4, 5] is suitable for this calculation. For calculation of individual velocities and moments we use the well-known relationships between kinematic and moment parameters of spur and planetary gears. In the calculation we can set the transmission efficiency η X = 100%, so all the parameters were investigated with a theoretical lossless power transmission. For simplification it is advisable to calculate using relative parameters. Therefore we apply ω = 1, M = 1, P = 1 and other values ω, M and P of random transmission components are the JROSLV PITOŇÁK, MIROSLV GLBVÝ, JURJ PRODJ MECC PGE 2

3 Speed gear nr. Engaged shifting element S1 S2 S3 B1 B2 B3 S4 S5 Transmission ratio Gear differentiation 0 X X X X 13,6 1,7 1 X X X X 8 1, X X X X 6,0444 1,2 3 X X X X 5,037 1, X X X X 4,1846 1, X X X X 3,443 1, X X X 2,7475 1,272 7 X X X X 2,16 1, X X X X 1,632 1,2 9 X X X X 1,36 1, X X X 1,1298 1, X X X 0,9296 1, X X X X 0,7418 FIGURE 1: The flow diagram of the powershift differential transmission with three flows of power. OBRÁZOK 1: Blokové usporiadanie trojtokovej diferenciálnej prevodovky s radením pod zaťažením. TBLE 1: The gearing diagram for the differential transmission with three flows of power. TBUĽK 1: Plán radenia prevodových stupňov trojtokovej diferenciálnej prevodovky. FIGURE 2: Schematic designation of transmission components, countershaft gears i 1,2,3, internal transmission ratios u v1,2 and additional gears i p1,2. input shaft, X output shaft, S clutch, B brake. OBRÁZOK 2: Schematické označenie členov prevodovky, predradených prevodov i 1,2,3, vnútorných prevodových pomerov u v1,2 a prídavných prevodov i p1,2. vstupný hriadeľ, X výstupný hriadeľ, S spojka, B brzda. FIGURE 3: The diagram of values of transmission ratio i X and gear differentiation φ according to the gearing plan of transmission. OBRÁZOK 3: Grafický priebeh hodnôt prevodového pomeru i X a prevodového skoku φ podľa plánu radenia jednotlivých prevodových stupňov prevodovky. FIGURE 4: Diagram of the solved differential transmission with designation of the angular velocities ω, torque moments M and powers P on all components. OBRÁZOK 4: Schéma riešenej trojtokovej diferenciálnej prevodovky s označením uhlových rýchlostí ω, momentov M a výkonov P na jednotlivých jej členoch. JROSLV PITOŇÁK, MIROSLV GLBVÝ, JURJ PRODJ MECC PGE 3

4 TBLE 2: The relative values ω, M a P on individual transmission components. TBUĽK 2: Pomerné hodnoty ω, M a P na jednotlivých členoch prevodovky. multiples of input shaft parameters. Table 2 lists all relative values of ω, M and P for individual transmission components at all gear speeds. The values in Table 2 were verified with the aid of the simulation software SimDriveline (Figure 5). SimDriveline is an expansion package for Matlab software which adds tools intended for designing and simulating vehicle-drive-mechanics [6,7]. The blocks we work with describe the preferences of individual transmission components directly, so it is not necessary to define the preferences and relative relationships mathematically. In this environment it is possible to input all the data into the block preferences. lso, the relationship between blocks is not defined as a signal transmission, but as a mechanical coupling. The mathematical relationships are not entered into the software, because it generates them automatically. This means that the software can be used to verify all the solutions and can be considered a reliable tool for solution verification. 6. TRNSMISSION POWER FLOWS From the calculated theoretical values of moments and velocities on a specific component it is easy to define the power transmitted by this component [4,5]: P = M ω (9) For a clear overview Table 2 offers all the values of transmitted power by all transmission components. Figure 6 explains the power distribution (if it appears) between the branches. These parameters were also examined under the theoretical condition of a lossless power transmission. JROSLV PITOŇÁK, MIROSLV GLBVÝ, JURJ PRODJ MECC PGE 4

5 FIGURE 5: The physical model of the transmission used for calculation verification of values of ω, M a P. OBRÁZOK 5: Fyzikálny simulačný model diferenciálnej prevodovky na overenie hodnôt ω, M a P získaných výpočtom. FIGURE 7: The physical model of transmission used for calculation verification of transmission efficiency. OBRÁZOK 7: Fyzikálny simulačný model trojtokovej diferenciálnej prevodovky na overenie účinnosti prevodovky získanej výpočtom. 7. TRNSMISSION EFFICIENCY The algorithm for parameter calculation also solves the theoretical transmission efficiency [1, 2]. The efficiency of the outer gear mesh was set at 0.98 (efficiency of countershaft gears and additional gears), the internal efficiency of the planetary set was considered to be 0.97 and all other power losses were ignored. Table 3 shows the overall transmission efficiency at each gear speed. The computed values were also verified using SimDriveline (Figure 7). 8. CONCLUSION Differential transmissions offer the ability to accommodate the requirements for large numbers of gear speeds. For example, the combination of two planetary sets provides 36 possible structures Speed gear nr. Transmission ratio Transmission efficiency 0 13,6 0, , ,0444 0, ,037 0, ,1846 0, ,443 0,95 6 2,7475 0, ,16 0, ,632 0, ,36 0, ,1298 0, ,9296 0, ,7418 0,9187 TBLE 3: The transmission efficiency at individual gear speeds. TBUĽK 3: Účinnosť prevodovky na jednotlivých prevodových stupňoch. JROSLV PITOŇÁK, MIROSLV GLBVÝ, JURJ PRODJ MECC PGE 5

6 and every structure enables a different gear speed redistribution. The chosen concept seems suitable for exploitation in freightvehicle-drives because of its number of available gear speeds and their differentiation. The described transmission enables a powershift meeting the actual requirements for vehicle transmissions. To achieve thirteen gear speeds, eight control components are needed. The advantage of this type of transmission is the fact that as opposed to a countershaft transmission, it does not need the same number of gear meshes as the achieved number of gear speeds. The result is that the transmission efficiency of a differential transmission is higher. Theoretically computed kinematic and moment characteristics are in accordance with the values achieved by simulations, and this also applies to the theoretical efficiency of individual gear speeds. There is no power circulation in the transmission; at several gear speeds a power split appears only. It would be appropriate to focus on engine and transmission cooperation within the overall drive function and also on the design of the control system. CKNOWLEDGEMENTS This contribution has been elaborated with the support of the project PVV Intelligent diagnostic systems of transmissions and their components. REFERENCES [1] Pitoňák J. & Galbavý M. (2011). Metodika návrhu parametrov diferenciálnych prevodoviek s využitím algoritmov. Technical computing Prague 2011, sborník příspěvků 19. ročníku konference. ISBN [2] Pitoňák J. & Galbavý M. (2011). Design of differential transmission with higher number of gear ratios. 52. konference kateder částí a mechanismů strojů s mezinárodní účastí: sborník referátů. ISBN [3] Málik L., Chrzová J. & Šoška M. (2007). Konštruovanie III. Žilina, EDIS vydavateľstvo ŽU. ISBN [4] Ikrinský. (2003). Mechanické a hydraulické prevody. Vydavateľstvo STU Bratislava, 2003, ISBN [5] Naunheimer H., Bertsche B. & Ryborz J. (2011). utomotive transmissions Fundamentals, Selection, Design a pplication. Springer Verlag Berlin Heidelberg. ISBN [6] SimDriveline 1 User s Guide. (2010). Mathworks Documentation, The MathWorks Inc. [7] The Humusoft materials: Matlab a Simulink. FIGURE 6: The power flows in the examined transmission with percentage of power at each branch for all gear speeds. OBRÁZOK 6: Toky výkonu v riešenej trojtokovej diferenciálnej prevodovke s percentuálnym podielom prenášaného výkonu konkrétnou vetvou na jednotlivých prevodových stupňoch. JROSLV PITOŇÁK, MIROSLV GLBVÝ, JURJ PRODJ MECC PGE 6