Engine and Vehicle Design and Performance

This document discusses the factors affecting vehicle performance and design, including air resistance, gradient resistance, and rolling resistance. It provides equations and calculations for performance loss terms and explores different gear ratios and their impact on power and fuel consumption. The document also discusses the types of vehicles based on tractive force and speed, as well as engine clutch delivery torque and regenerative braking energy.

Engine and Vehicle Design and
Performance
Done by:
Contents
TASK 8..........................................................................................................................................................1
TASK 9..........................................................................................................................................................4
TASK 10........................................................................................................................................................7
TASK 11.....................................................................................................................................................11
References:................................................................................................................................................13

TASK 8
A. Write an equation for Performance loss terms of a Vehicle:
The Performance of an Automobile depends upon various factors such as vehicle
resistance, coefficient of friction, the contact area of the wheel to the surface, engine
capacity, gearbox ratios, etc.
In this session the Vehicle Resistance characteristic of a vehicle and the terms
associated with it will be explained:
The Vehicle Resistance comes into play while designing a transmission system for
Automobiles. In general, the Vehicle Resistance Characteristics depends upon the four
terms such as (Hooftman, et al, 2018):
1. FL : Air Resistance.
2. Fst : Gradient Resistance.
3. FR : Rolling Resistance of the wheel.
1. FL Air Resistance:
The Air resistance Force can be calculated as:
FL=0.5 ρ Cd A v2
Where,
FL is the Air drag in N
ρ is the Density of the fluid (air) in Kg/m3
Cd is the Coefficient of drag
A is the frontal area of the moving object. In m
V is the Velocity of the car in m/s
2. Fst, Gradient Resistance:

The Gradient Resistance can be mathematically expressed as:
Fst=M v . g .sin Gst
Where,
Mv is the Mass of the Vehicle in Kg
g is the Acceleration due to gravity in m/s2
Gst is the slope of the track in degrees.
3.Rolling Resistance of a vehicle:
Mathematically Rolling resistance can be termed as:
FR =C . Mg
Where,
C is the Rolling resistance coefficient
M is the mass of the vehicle in Kg
g is the Acceleration due to gravity in m/s2
B.
1. Air Resistance:
Whenever an object moves in a fluid medium, the Fluid medium will excert an opposing
friction force on that object. This opposing friction force is known as air resistance or air
drag. The drag force increases the Fuel consumption of a car, it is important to design
the car in a most aerodynamic way (tendency to withstand drag force and to avoid
turbulent end conditions). The air drag of a vehicle must be taken into consideration
while designing the vehicle (Hooftman, et al, 2018).

2. Gradient Resistance:
Whenever an automobile moves uphill or downhill, a resistive force is acted on the
vehicle, which is known as force due to gravity or Gradient Resistance. It occurs due to
the weight acting at the centre of gravity of the vehicle (Bian and Qiu, 2018) (Babu,
2015).
3. Rolling Resistance:
The rolling resistance is the amount of force that resists the motion of a body when it
rolls on a surface. In case of a car rolling resistance acts on the wheel, the tire must be
capable of overcoming the resistance offered by the road surface to set the vehicle in
motion (Hu, et al, 2017) (burns, et al, 2017)
TASK 9
Given data:
First Gear Ratio: 2.95
2nd Gear Ratio: 2.50
3rd Gear Ratio: 1.99
4th Gear ratio: 1.42
5th Gear ratio: 0.9
Differential Ratio: 3.48
Overall Transmission efficiency: 87 %
Wheel Radius: 0.36 m
The different Torque can be found at:

T = P 60
2 πN
T torque in n.m
Power, P in KW
N in RPM
Tf = T/ Reduction ratio
Now,
Considering Various N Rpm of the Engine.
Let Power P of the Engine be 80 KW
The Speed of the engine varies from 1000 to 6600 RPM
Now,
1.
T =80 ( 60 ) /2 π ( 6600 ) ( 2.95 ) ( 0.87)
T =295 Nm
2.
T =80 ( 60 ) /2 π ( 4500 ) ( 2.5 ) ( 0.87 )
T =369 Nm
3.
T =80 ( 60 ) (1.99)(0.87)/2 π ( 3800 )
T =348 Nm

4.
T =80 ( 60 ) /2 π ( 3000 ) (1.42)(0.87)
T =314 Nm
5.
T =80 ( 60 ) /2 π ( 1500 ) ( 0.9 ) ( 0.87 )
T =200 Nm
Calculation of power:
P1 = 2 π N T/60
P1 = 57 KW
P2 = 2 π N T/60
P2 = 115 KW
P3 = 2 π N T/60
P3 = 146 KW
P4 = 2 π N T/60
P4 = 173 KW
P5 = 2 π N T/60
P5 = 255 KW
Tabulation:
S.No Speed N RPM Power in KW Torque in NM
1. 1500 57 295
2. 3000 115 369
3. 3800 146 348

4. 4500 173 314
5. 6600 255 200
Graph:
Torque Vs Power Vs Speed
1500 3000 3800 4500 6600 0
50
100
150
200
250
300
0
50
100
150
200
250
300
350
400
Chart Title
Power Nil Torque
Axis Title
Power in KW
Torque in Nm
As per the Gear ratios and road speed the car is suitable to be serviced as a city cruiser
due to its linear power delivery and high torque at middle Rpm. This car suits best as a
touring / cruising vehicle with medium weight category (Zhao, et al, 2015) (Nefcy, et al,
2016).
TASK 10
Given data:
W, Vehicle weight : 8700[N]
Fd, Coefficient of rolling resistance : 0.02 [-]
R, Wheel Radius : 0.31[m]
Slip, Wheel slippage : 4 [%]

GRR, Gear reduction ratio : 2,65 [-]
DR, Axle(differential) transfer ratio : 3.4 [-]
A, Maximum cross-sectional area : 1.83[m2]
G, Road grade : 0 [o]
CdDrag coefficient : 0.445 [-]
Sw, Wind speed : 0 [m/s]
p, Density of atmospheric air : 1.22[kg/m3]
1.
To find: Road speed
Given that:
PL = PR: FL = FR
Now,
Power = Force (Velocity)
Drag force:
FL=0.5 ρ Cd A v2
FL is the Air drag in N
ρ is the Density of the fluid (air) in Kg/m3
Cd is the Coefficient of drag
A is the frontal area of the moving object. In m
V is the Velocity of the car in m/s
FL=0.5 ( 1.22 ) ( 0.445 ) ( 1.83 ) (15)2=111.76 N

Rolling Resistance:
FR =C . Mg
Where,
C is the Rolling resistance coefficient
M is the mass of the vehicle in Kg
g is the Acceleration due to gravity in m/s2
FR =0.02 ( 8700 ) =174 N
Let us assume that the power spent is 50 KW
P=FR (V )
V = P
FR
= 50,000
174 =287 m
s =642 Mph
The road speed is calculated as 287 m/s
V = πDN /60
N = 15252 Rpm
2. Engine speed at that particular road speed (Park, 2015):
RPM = Mph ( Transmissionratio ) ( 336 )
Doftire =5398 Rpm
The engine Speed will be 5398 Rpm
3. Power of the Engine:
P = 2 π N T/60
Torque: can be found from Speed as

T =F . r =174 ( 0.36 ) =62.64 Nm
P = 35.408 KW
The power is found to be 35 Kilo watt.
B.
Given:
3rd gear: 1.692
4th gear: 1.294
nD =3.260
D= 0.31 m
P = 50 HP
V = 108 Kmph
From the provided data and the graph, we can see that the gear shifting is done at 50
Hp and it is required to maintain the speed of the vehicle at 10 Km/hr. Now we need to
find the Fuel consumption change upon shifting the gear.

The gear ratio for the Gear 3 is 1.692 and for the gear 4 is 1.294 Now we can
understand that the gear ratio is lowered for the Gear 4 which is to be shifted next as
the velocity of the vehicle is kept constant also assuming all other factor remains the
same (CHIMBE, et al, 2019).
Now Ratio difference:
Dr = 1.692 / 1.294 = 1.3075
So as the gear ratio is improved the fuel consumption will be reduced by the factor
1.3075. Higher the gear lower the fuel consumption.
Be = 130.75 % - 100% = -30.75 %
The fuel consumption will be reduced by 30.75 %
TASK 11
To find: Which curve belong to which type of vehicle.
For the first Yellow curve:
Tractive force at wheel 289 Km/h = 3104 N
Tractive force of engine at 120 Km/h = 500 N
Vehicle Type: Low Torque High Speed

For the Second Curve
Tractive force at wheel 236 Km/h = 33836 N
Vehicle Type: Low torque and High-speed engine.
For the third blue curve:
Tractive force at wheel 190 Km/h = 4708 N
Vehicle Type: Medium torque and medium speed engine.
For the Fourth curve
Tractive force at wheel 142.5 Km/h = 5951 N
Vehicle Type: Medium torque and medium speed engine.
For Fifth curve:
Tractive force at wheel 190 Km/h = 4708 N
Vehicle Type: High torque and low-speed engine.
For 6th curve:
Tractive force at wheel 60 Km/h = 11000 N
Vehicle Type: Very high torque and low-speed engine.

References:
Babu, P.S., 2015. Analysis of Developing New Smart Systems in Automobile
Transmissions. The International Journal of Science and Technoledge, 3(1), p.104.
Bian, J. and Qiu, B., 2018. Effect of road gradient on regenerative braking energy in a
pure electric vehicle. Proceedings of the Institution of Mechanical Engineers, Part D:
Journal of Automobile Engineering, 232(13), pp.1736-1746.
Burns, K.J., Balmforth, N.J. and Hewitt, I.J., 2017. Rolling resistance of shallow granular
deformation. Proceedings of the Royal Society A: Mathematical, Physical and
Engineering Sciences, 473(2207), p.20170375.
CHIMBE, T., Tsukamoto, N., Ota, K., Asami, T., Kajiyama, Y. and Fukuda, D., Toyota
Motor Corp, 2019. Control device of vehicle. U.S. Patent Application 10/167,947.
Hooftman, N., Messagie, M., Van Mierlo, J. and Coosemans, T., 2018. A review of the
European passenger car regulations–Real driving emissions vs local air
quality. Renewable and Sustainable Energy Reviews, 86, pp.1-21.
Hu, X., Guo, H., Qian, H., Ding, X. and Yang, Y., 2017, October. Development of a high-
power-density motor for formula SAE electric race car. In IECON 2017-43rd Annual
Conference of the IEEE Industrial Electronics Society (pp. 6618-6622). IEEE.
Nefcy, B.D., Connolly, F.T., Colvin, D., Ortmann, W.J., Kraska, M.P., Crombez, D.S.
and Yamazaki, M.S., Ford Global Technologies LLC, 2016. Torque modulation in a
hybrid vehicle downshift during regenerative braking. U.S. Patent 9,493,148.
Park, J., Hyundai Motor Co and Kia Motors Corp, 2015. System and method for
detecting engine clutch delivery torque of car. U.S. Patent 9,014,894.
Zhao, Z.G., Chen, H.J., Yang, Y.Y. and He, L., 2015. Torque coordinating robust control
of shifting process for dry dual clutch transmission equipped in a hybrid car. Vehicle
System Dynamics, 53(9), pp.1269-1295.