guc aktarma_gırıs_ıı_2014-2015

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
Benzin motorlu 1200 kg'lık bir otomobilde 90 km/h hızda yakıt enerjisinin %
(yüzde) olarak kullanımı [14]
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
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
sürekli rejim, kararlı hal.
durum,
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. FR=RFz şeklinde formüle edilir.
FR = fR (FzÖ +
Abdullah Demir,Y.L.Tezi
Yuvarlanma Direnci
Composed primarily of

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/m3 hava
yoğunluğu (1.0133 bar ve 15 oC
da)
Cd*: hava direnci katsayısı
Otomobillerde 0,3 - 0,4;
kamyonlarda 0,8
A : kesit alanı. Otomobillerde
1.85 m2 ; kamyonlarda 8 m2
alınabilir.
* Not: Bazı kaynaklarda cd bazı kaynaklarda
cw olarak kullanılmaktadır.
Aerodynamic effects on vehicle functions
Bosch Automotive Handbook
Araç Aerodinamiği
Effect of cw·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
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
Bosch Automotive Handbook
Brake cooling devices
+2...+5
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.
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: 978-0-47097633-3
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: 978-0-47097633-3
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: 978-0-47097633-3
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: 978-0-47097633-3

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