Güç Aktarma Organları -Giriş- Yrd. Doç. Dr. Abdullah DEMİR HAZIRLAYAN: Yrd. Doç. Dr. Abdullah DEMİR
Araçlarda Enerji Yönetimi Kaynak: Dr. Athanasios Vikas, Automotive Technology Individual Mobility 2020, Robert Bosch GmbH 2009.
Drivetrain Loses Energy flow in a typical present day car (8.9 litres/100 km, 26.4 mpg) (left) and advanced vehicle (4.0 litres/100 km, 58.4 mpg) (right) Energy and the New Reality, Volume 1: Energy Efficiency and the Demand for Energy Services Chapter 5: Transportation Energy Use, L. D. Danny Harvey
Drivetrain Loses A vehicle s drivetrain loses energy mainly through friction in the transmission and bearings. Passenger car powertrain losses Bernd Heißing Metin Ersoy (Eds.), Chassis Handbook Fundamentals, Driving Dynamics, Components,Mechatronics, Perspectives, 1st Edition 2011.
Enerji Dağılımı Kaynak: Mak. Müh. Tayfur Kerem DEMİRCİOĞLU, Bir Araç Modelinin Aerodinamik Analizi ve Sonlu Elemanlar Yöntemi İle Simülasyonu, Balıkesir Üniversitesi Fen Bilimleri Enstitüsü Makine Mühendisliği Anabilim Dalı, Yüksek Lisans Tezi, Balıkesir, Ağustos 2007 Benzin motorlu 1200 kg'lık bir otomobilde 90 km/h hızda yakıt enerjisinin % (yüzde) olarak kullanımı [14]
Taşıt direnç ve tahrik kuvvetleri As shown in Figure 1, vehicle resistances opposing its movement include rolling resistance of the tires, appearing in Figure 1 as rolling resistance torques Trf and Trr, aerodynamic drag, Fw, and hill climbing resistance (the term Mg sin α in Figure 1). FIGURE 1 Forces acting on a vehicle moving uphill. Kaynak: Modern Electric, Hybrid Electric and Fuel Cell Vehicles - Fundamentals, Theory and Design 2nd by Ehsani, 2010
Taşıt direnç ve tahrik kuvvetleri Consider the first three of these that occur during steady-state conditions steady-state: Kararlı/Daimi durum, sürekli rejim, kararlı hal. Headwind: karşıdan esen rüzgar Edited by David A. Crolla, Automotive Engineering Powertrain, Chassis System and Vehicle Body; Butterworth-Heinemann, 2009
Yuvarlanma Direnci Güç, sınırlayıcı kuvvetlerin üstesinden gelmek için sarfedilmek zorundadır. Bunlardan bir tanesi de yuvarlanma direncidir. Yuvarlanma direnci; aracın yüklü ağırlığına, yol yüzeyinin türüne ve lastik üretiminde kullanılan malzemelere, yapı ve dizaynlara bağlı olarak değişir. Yuvarlanma direncini oluşturan ikincil nedenler olarak; tekerlek yatağı, yağ keçesi sürtünmesi ve transmisyon sistemindeki yağın çalkalanmasıdır. Yuvarlanma direnci, tekerlek yuvarlanırken zeminle temas bölgesinin ezilmesi, bu bölgeye giren lastik elemanlarının sıkışması, çıkan elemanların uzaması, bu olayın zeminde asimetrik bir basınç doğurması ve sıkışıp uzama olayının kayıplı olmasından kaynaklanmaktadır. Yuvarlanma direnç katsayısı R ile gösterilir ve R = a/r olarak formüle edilir. Burada; a= Tekerlek yükünün etkime noktasının eksenden kaçıklığı, r= Tekerlek statik yarıçapı olarak tanımlanır. Yuvarlanma direnci, yuvarlanma direnç katsayısı ile tekerlek yükünün çarpılması neticesinde bulunur. F R = R F z şeklinde formüle edilir. FR = fr (FzÖ + Abdullah Demir,Y.L.Tezi
Composed primarily of Yuvarlanma Direnci Resistance from tire deformation ( 90%) Tire penetration and surface compression ( 4%) Tire slippage and air circulation around wheel ( 6%) Wide range of factors affect total rolling resistance
Yuvarlanma Direnci The rolling resistance of tires on hard surfaces is primarily caused by hysteresis in the tire materials. Figure shows a tire at standstill, on which a force, P, is acting at its center. The pressure in the contact area between the tire and ground is distributed symmetrically to the central line and the resultant reaction force, Pz, is aligned to P. The deformation, z, versus the load, P, in the loading and unloading process is shown in Figure 2.3. To keep the wheel rolling, a force, F, acting on the center of the wheel is required to balance this rolling resistant moment. This force is expressed as. Pressure distribution in contact area. Kaynak: Modern Electric, Hybrid Electric and Fuel Cell Vehicles - Fundamentals, Theory and Design 2nd by Ehsani, 2010
Yuvarlanma Direnci FIGURE 2.3 Force acting on a tire versus tire deformation in loading and unloading. Kaynak: Modern Electric, Hybrid Electric and Fuel Cell Vehicles - Fundamentals, Theory and Design 2nd by Ehsani, 2010
Yuvarlanma Direnci where rd is the effective radius of the tire and fr = a/rd is called the rolling resistance coefficient. In this way, the rolling resistant moment can be equivalently replaced by a horizontal force acting on the wheel center in the opposite movement direction of the wheel. This equivalent force is called rolling resistance with a magnitude of FIGURE 2.4 Tire deflection and rolling resistance on a (a) hard and (b) soft road surface. Kaynak: Modern Electric, Hybrid Electric and Fuel Cell Vehicles - Fundamentals, Theory and Design 2nd by Ehsani, 2010
Yuvarlanma Direnci A.G. GÖKTAN, A. GÜNEY, M. EREKE, TAŞIT FRENLERİ Kaynak: Modern Electric, Hybrid Electric and Fuel Cell Vehicles - Fundamentals, Theory and Design 2nd by Ehsani, 2010
Eğim Direnci Eğim direnci, araç eğik düzlemde çıkış yaparken yenilmesi gereken yerçekimi kuvvetidir. Eğim genellikle % olarak ifade edilir. Yokuş tırmanırken arka dingil basıncı artacağından arkadan itişli araçlar avantajlı bir durumuna gelir. Meyiller ufak olduğunda (yani p %20 den küçük olunca, diğer bir küçük açılarda -%2 den daha az hata olacak şekilde- sin = tan dır.) sin α = tg α = p kullanılır Fcl = m g p Ağırlık/güç oranı: Araç performansının ve ivmelenme kabiliyetinin bir ölçüsü ağırlık/güç oranıdır. Bir aracın ağırlık/güç oranı ne kadar küçük olursa, o aracın ivmelenme ve tırmanma kabiliyeti o oranda büyük olur. Her araç için optimum ağırlık/güç oranı vardır. Aracın tırmanma yeteneği: Motorlu taşıtın azami yüklü ağırlığı ile tırmanabildiği en yüksek eğimin yataya göre tanjant cinsinden yaptığı açının yüzde (%) olarak ifade edilen değeridir. Bir aracın ağırlık/güç oranı ne kadar küçük olursa, o aracın ivmelenme ve tırmanma kabiliyeti de o oranda büyük olur. Örnek: 2002 model Toyota Corolla 1.6 Sol Sedan otomatik araç için tırmanma açısı dizayn değeri, yaklaşık 18 derece (%33 eğim) olacak şekilde üretilmiştir. Bu değer; aracın yük durumu, elektrik yükü, motor ve şanzıman, vs. durumu gibi etkenlerle oldukça etkilenmektedir. Şanzıman tipi: A246E - Otomatik şanzıman Vites oranları: 1. Vites: 4,005 2. Vites: 2,208 3. Vites: 1,425 4. Vites: 0,981 Geri Vites: 3,272 Diferansiyel oranı: 2,962
Eğim Direnci Reading Text: Grading Resistance When a vehicle goes up or down a slope, its weight produces a component that is always directed in the downward direction, as shown in Figure. This component either opposes the forward motion (grade climbing) or helps the forward motion (grade descending). In vehicle performance analysis, only uphill operation is considered. This grading force is usually called grading resistance. Grading resistance, referring to Figure, can be expressed as Fg = Mg sin α. To simplify the calculation, the road angle, α, is usually replaced by the grade value, when the road angle is small. As shown in Figure, grade is defined as p =H/L = tan α sin α In some literature, the tire rolling resistance and grading resistance together are called road resistance, which is expressed as Frd = Ff + Fg = Mg(fr cos α + sin α).
Eğim Direnci When the road angle is small, the road resistance can be simplified as Frd = Ff + Fg = Mg(fr + p). FIGURE: Vehicle climbing a grade
Araç Aerodinamiği Composed of: 1. Turbulent air flow around vehicle body (85%) 2. Friction of air over vehicle body (12%) 3. Vehicle component resistance, from radiators and air vents (3%)
Araç Aerodinamiği Aerodynamic drag is calculated as ρ = 1.226 kg/m 3 hava yoğunluğu (1.0133 bar ve 15 o C da) C d *: hava direnci katsayısı Otomobillerde 0,3-0,4; kamyonlarda 0,8 A : kesit alanı. Otomobillerde 1.85 m 2 ; kamyonlarda 8 m 2 alınabilir. * Not: Bazı kaynaklarda c d bazı kaynaklarda c w olarak kullanılmaktadır. Aerodynamic effects on vehicle functions Bosch Automotive Handbook
Araç Aerodinamiği Effect of c w A on fuel consumption (mid-sized vehicle) Effect of Δcd in % Lowering vehicle height by 30 mm approx. 5 Smooth wheel covers 1... 3 Wide tires +2...+4 Windows flush with exterior approx. 1 Sealing body gaps 2... 5 Underbody panels 1... 7 Concealed headlamps +3...+10 Outside rear-view mirrors +2...+5 Airflow through radiator and engine compartment +4...+14 Brake cooling devices +2...+5 Table 1. cw values for various vehicles Vehicle (Examples) cd A / m2 Audi A8 0,29 2,25 Porsche 911 0,29 1,95 Mercedes C 200 D 0,30 2,05 Interior ventilation approx. +1 Open windows approx. +5 Open sunroof approx. +2 Roof-mounted surfboard rack approx. +40 Note: During the early stages in the design and development process most testing is performed using small scale models where ¼ scale is the most popular. Bosch Automotive Handbook
Araç Aerodinamiği α cd Δcd in % 50 0.345 55 0.342 0.8 65 0.340 1.4 40 0.349 + 1.1 30 0.349 + 1.1 0 0.369 + 7.0 Effect of windshield slope α on the cd value see Table ( = better, + = worse) Bosch Automotive Handbook
The performance of a vehicle is usually described by its maximum cruising speed, gradeability, and acceleration.
EKLER
The vehicle s main components and sub - systems can be categorically listed as: Power - train, chassis, exterior and interior trims, and the body in white (BiW) or vehicle body - shell. Mohammed A. Omar, The Automotive Body Manufacturing Systems and Processes, 2011 John Wiley & Sons Ltd. ISBN: 978-0-470-97633-3
The power - train is composed of the prime - mover (the internal combustion engine, or electric motor), the gear system, and the propulsion and drive shafts, while the chassis includes the suspension and steering components, in addition to the wheel, tires, and axles. The interior and exterior trims compose the front and rear ends, the door system, and the cockpit trim. Finally, the body in white is made up of the closures (doors, hood, tail - gate) and the frame, see Figure 1 ). Mohammed A. Omar, The Automotive Body Manufacturing Systems and Processes, 2011 John Wiley & Sons Ltd. ISBN: 978-0-470-97633-3
The frame can be of a uni - body design (Figure 1.1 (a) uni - body), a body - on - frame (Figure 1.1 (b)), or a space - frame (Figure 1.1 (c)). The uni - body design features stamped panels, while the space - frame is made up of extrusions and cast parts. The BiW closures are selected based on the vehicle s constituent material dent - resistance properties (i.e. yield strength) while the frame is designed to provide specific torsional and bending stiffness. Figure 1.1: Top left: (a) a uni - body design, top, right: (b) truck platform; and bottom right: (c) space - frame design Mohammed A. Omar, The Automotive Body Manufacturing Systems and Processes, 2011 John Wiley & Sons Ltd. ISBN: 978-0-470-97633-3
A typical BiW consists of about 300 400 stamped pieces, however, only a few main panels affect the overall geometry, fit and finish. These panels are the roof, the trunk (inner, outer, and pan), the hood (inner and outer), the under - body, the wheel - house, the body - side, A and B pillars, the floor pan, the front module (engine cradle, crush zones, shock towers), the quarter panels, and doors (inner, outer). A-pillar A-direği/sütunu, A-dikmesi. Figure 1.3 The different panels of the vehicle structure Mohammed A. Omar, The Automotive Body Manufacturing Systems and Processes, 2011 John Wiley & Sons Ltd. ISBN: 978-0-470-97633-3