MAE7030-B Efficiency of the BEV Vehicle Assignment Sample

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• Subject Code : MAE7030-B
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Vehicle Powertrain and Dynamics

Executive summary of Vehicle Powertrain and Dynamics

The retail price of the battery operated vehicle is higher as compare with the ICV vehicle. The mechanical efficiency of the of BEV is higher as compare with the ICV engine. In his paper the some parameters are taken into consideration for calculation of gear ratio, Load transfer, Acceleration performance and some other performance parameter. The efficiency of the BEV vehicle is higher as compare to the ICV Vehicle.

Aims & objectives of Vehicle Powertrain and Dynamics

Electric car was there in their heyday beck in 1900.But sudden rise in petrol engine cars accompanied by battery technology inefficiencies killed cars by 1920. We will compare these totally different technologies scientifically, and come to understand which is superior

This research paper gives view the current scenario regarding the usage of the IC engine operated vehicle and what are the effect of the IC engine operated vehicle on the environment.

In this paper some performance parameter is been found that are used for the calculation of dynamic stability of the car.

The parameter that are incudes are Gear ratio, Rolling force ,Torque on wheels, Maximum speed of wheel, Acceleration Performance, load transfer on front and rear wheel And gradeability.

Calculations, Results and Analysis of Vehicle Powertrain and Dynamics

Force acting on vehicles:-

Taking some base line values for table :

Vehicle type:	2-seater sportscar
Top Speed	322 km/h
Desirable properties:	High performance
Peak Lateral acceleration	1.3 g
Peak longitudinal deceleration/deceleration	1.3 g
Target sales price:	£100,000
Baseline vehicle mass excluding powertrain:	1000 kg
Number of seats:	2
Vehicle CoG height:	400 mm (excl. powertrain, fuel & driver)
Vehicle CoG behind front axle:	1100 mm (excl. powertrain, fuel & driver)
Brake ratio (front:rear)	70:30
Front wheel rate	67000 N/m
Rear wheel rate	88000 N/m
Trackwidth	1800 mm
Wheelbase:	2400 mm
Prime mover:	Type (ICE/Hybrid/EV), mass & CoG position determined from research & engineering judgement
Energy source:	Type, mass & CoG position determined from research & engineering judgement
Wheel dia	30 Inches
Consider efficiency of gear ratio	= 80 %
Frontal area of car	2.28

 Calculate the Gear ratio :-

• Top speed 302 Km/h = 302*1000/60 = 5033.33 m/min
• Circumference of wheel = 2 * pi * r = 2* 3.14 * 0.381 = 2.39 meters
• Revolutions per minute = speed in meters per minute / circumference in meters.

= 5033.33/ 2.39 = 2106 Rpm

Considering max Rpm at wheel is 2106 Rpm and Minimum Rpm 800 rpm.

Min RPM = 800 RPM

Max RPM = 2106 RPM

Suppose our gearbox is having 6 speed Gear box

Follow the R 10 series

N1 = Nmin = 800 RPM

N2 = N1 x φ ^ 1 = 800 x 1.22^ 1 = 976 RPM

N3 = N1 x φ ^ 2 = 800 x 1.22 ^ 2 = 1190.72 RPM

N4 =N1 x φ ^ 3= 800 x 1.22 ^ 3 = 1452.678 RPM

N5 = N1 x φ ^ 4= 800 x 1.22 ^ 4 = 1772.2676 RPM

N6 = Nmax = 2106 RPM

Gear ratio = 2106 / 800 = 2.63

In first stage

 i1 = 976 / 800 = 1.22

i2 =1772.267 /800 = 2.21

In second stage

i3= 800 / 976 = 0.82

i4= 1452.678 / 976 =1.5

Final drive gear ratio = 2.1

• Torque on the wheel which is transmitted by engine and gear box.

Tw = ig . i0 . η . Tp

= 1.2 X 2.1 x 0.8 x 88000

= 199584 N.m

• The tractive effort on the driven wheels : -

FT = ig . i0 . η . Tp / rd

= 199584 / 0.35

= 570240 N

• Aerodynamic drag can be solved by ;-

Fw= (1/2) ρa x Cd x Af x V ^ 2

= ½ x 1.2 x 0.3 x 2.28 x 322 ^ 2

= 42551.91 N

• Rolling resistance can be could by

Ff = Mv x g x Fr

= 1000 x 9.81 x 0.13

= 1257.3 N

• Angular momentum of wheel = 0.5 m r^2 x w

= 0.5 x 15 x (0.3)^2 x 83.73

= 56.52 kg*m^2*s^-1

• δ is called the mass factor = 1+ ( Iw /Mv x rd^2)

= 1 + (56.52 / 1000 x 0.3 ^2)

= 1.63

• Acceleration Performance = Ft – Ff - FW / δ Mv

= 570542 – 42551.91 – 1257. 3 / 1000* 1.19 * 9.81

= 48.73 km / hr

• The normal load on the front axle Wf can be determined as

Wf = 1.8 / 2.4 x 1000 x 9.81 x cos 0 - 1.1/3( 42551.91 +1000 x 9.81 sin 90 + 1000 * 9.81 * 0.13+1000* (0.3/1.1) / 2.4

= 7357.5-3772.93

= 3584.57 N

• The normal load on the front axle Wr can be determined as

Wr = 0.6/2.4 x 1000 x 9.81 x cos0 + 1.1 /3 ( 132 +1000 x 9.81 sin 90 + 1000 * 9.81 * 0.13 + 1000 * ( 0.3 / 1.1 )

= 2452.5 + 3772.93

= 6225.93 N

• Grade ability

d = 570240 – 42551.91 / 1000*9.81 = 53.79

I = d-f = 53.79 - 0.013 = 58.77

Discussion of Vehicle Powertrain and Dynamics

After doing the calculation following result were obtain:-

The first and second stage gear ratio is Gear ratio = 2106 / 800 = 2.63

In first stage

 i1 = 1.22

i2 =2.21

In second stage

i3= 800 / 976 = 0.82

i4= 1.5

The Rolling resistance is found after doing the calculation of given data is we got result Ff = 1257.3 N .The aerodynamics drag is 42551.91 N and values of tractive effort is FT = 570240 N.

The acceleration performance is a = 48.73 km / hr. The normal load on the front axle Wf is 3587.57 N and at the rear axle is 6225.95N.The values of gradably is found as 53.78.

Conclusion on Vehicle Powertrain and Dynamics

After doing the above calculation we got the result. In this experiment the efficiency of transmission is taken as 80% but if we increase the values then the traction force is increase as well as the torque which is available at the wheels. If the values of gear ratio can increase the acceleration performance the engine if the ratio is higher than the acceleration value is also higher. The maintenance cost is also less in Battery vehicles.

References for Vehicle Powertrain and Dynamics

Long, G. (2000). Acceleration Characteristics of Starting Vehicles. Transportation Research Record, 1737(1), 58–70. https://doi.org/10.3141/1737-08

Velenis, Efstathios & Frazzoli, Emilio & Tsiotras, Panagiotis. (2010). Steady-state cornering equilibria and stabilisation for a vehicle during extreme operating conditions. Int. J. of Vehicle Autonomous Systems. 8. 10.1504/IJVAS.2010.035797.

Bakker, Battery Electric Vehicles, D.P. (2010) Faculty of Geosciences Theses,(Master thesis), Utrecht University Repository

Elnozahy, Ahmed & Abdel-Rahman, Ali Kamel & Ali, Prof. Dr. Eng, Ahmed Hamza H. & Abdel-Salam, Mazen. (2014). A Cost Comparison between Fuel Cell, Hybrid and Conventional Vehicles.

MacKenzie, D., & Heywood, J. (2012). Acceleration Performance Trends and Evolving Relationship between Power, Weight, and Acceleration in U.S. Light-Duty Vehicles: Linear Regression Analysis. Transportation Research Record, 2287(1), 122–131. https://doi.org/10.3141/2287-15

Sugawara, Y., Akasaka, Y., and Kagami, M., "Effects of Gasoline Properties on Acceleration Performance of Commercial Vehicles," SAE Technical Paper 971725, 1997, https://doi.org/10.4271/971725

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