POWERTRAIN-1

TASK-1

Given –

Brake power = 5.5kW,

Engine Speed = 3500 rpm

Mechanical Efficiency = 75%

BSFC=0.28 kg/kWh

Calorific value of fuel= 43 MJ/kg

Volumetric Efficiency =85%

Intake air temperature = 25°C = 298 K

Intake air pressure =1 atm = 101.325 kPa

Air-Fuel Ratio = 14.7:1

Specific gas constant for air = 287 J/kg·K

a) Mechanical efficiency = brake power/indicated power

Therefore, indicated power = brake power/mechanical efficiency
Indicated power = 5.5/0.75=7.33kW

b) Bsfc=fuel consumption/brake power

Therefore, fuel consumption = bsfc*brake power
Fuel consumption = 0.28*5.5 = 1.54kg/hr

c) Mass flow rate of fuel = 1.54kg/hr= 0.000428 kg/s

Therefore massflow rate of air = 0.000428*14.7=0.00629 kg/s
Density of air = pressure/(R*T)= 101325/(287*298)=1.185kg/m^3
Massflow rate of air = engine displacement*engine speed*volumetric efficiency*density of
air/ (2*60)
Engine displacement = Massflow rate of air*2*60/ engine speed*volumetric
efficiency*density of air
= 0.00629 *120/3500*0.85*1.185
=0.000214 m^3 = 214ml = 214cc

d) Thermal efficiency = 1-(1/(r^(k-1))) where r is compression ratio and k is posion constant

There fore increase thermal efficiency, we can increase r. r = 1+ (swept vol./clearance vol.)
So we can decrease clearance vol.But this can lead to knocking.

We can also increase k by increasing airfuel ratio as k of air > k of petrol(or any other liquid
fuel).
TASK-2

Urban Compact City Car

Goal: Affordability, efficiency, maximum space utilization, frequent stop-and-go traffic, low-to-
moderate average speeds.

System Architecture: Single-Motor, Front-Wheel Drive because a FWD layout is economical to

produce. It combines the motor, inverter, and gearbox into a unit on the front axle and it eliminates
the need for a central transmission tunnel or rear driveshafts, maximizing cabin and luggage space.
FWD also provides sufficient traction and predictable handling.

Motor: single 50-80kW PMSM. Enough power for city driving and maximizes range from a smaller
battery.

Battery pack: 30-40 kWh Lithium Iron Phosphate (LFP) chemistry. Cheap, small in size, offers a higher
cycle life, ideal for vehicle that undergoes frequent shallow charge/discharge.

Cooling: air cooling, sufficient city driving.

Charging: 7.4kW AC charger. Enough for overnight charging.

Transmission: Single-Speed Reduction Gearbox. simple, lightweight, low-cost, efficient.

High-Performance Sports EV

Goal: High power, torque, dynamic capability, good stability and handling.

System Architecture: Dual-Motor, All-Wheel Drive because extreme performance as combined power
output of two motors will be high. This layout allows for instantaneous, precise, and independent
control of torque to the front and rear axles. This active torque vectoring dramatically improves
cornering grip, stability, agility. Also equal weight distribution in front and back for good handling.

Motor: Dual High-Power PMSM(each around 300kW).High torque and power for their size and
weight. Fast acceleration

Battery pack: Nickel Manganese Cobalt (NMC) Chemistry(80-100kWh). high energy and power
density. Hence battery is light and compact for given capacity.

Cooling: High-Capacity Liquid Cooling System. Dissipates enormous amounts of heat during repeated
acceleration runs or track laps to prevent thermal throttling, ensuring that the car can deliver its
peak performance consistently.

Charging: 250kW DC fast charger. Minimize downtime.

Transmission: Two-Speed Gearbox. The first gear provides acceleration from a standstill, while the
second gear allows for higher efficiency at cruising speeds and enables a higher vehicle top speed.
 POWERTRAIN-2

TASK-1

Feature Manual transmission Automatic Continuously variable Dual-Clutch transmission

transmission transmission

Diagram

Working The driver manually A fluid coupling called CVT uses a system of two DCT is two separate manual
principle disengages the engine a torque variable-diameter pulleys gearboxes working as one.
from the transmission converter connects the connected by a steel belt One gearbox controls the
using a clutch pedal. They engine to the or chain. One pulley is odd-numbered gears (1, 3, 5,
then use a gear lever to transmission, allowing connected to the engine etc.) and the other controls
physically select a gear the engine to idle and the other to the the even-numbered gears (2,
pair from a set of fixed while the car is wheels . By changing the 4, 6, etc.). Each gearbox has
ratios on parallel shafts stopped. Planetary effective diameter of the its own clutch. While one
inside the gearbox. gears are used to pulleys, the transmission gear is engaged, the
Synchronizers match the create different fixed can achieve an infinite computer pre-selects the
speeds of the gears gear ratios. A hydraulic number of gear ratios next likely gear on the other
before engagement to system, controlled by between its minimum gearbox. The shift is
ensure a smooth shift. the car's computer, and maximum limits. performed by simply
engages and disengaging one clutch and
disengages clutches engaging the other, resulting
and bands within the in instant gear change.
transmission to select
the appropriate gear
automatically.
Efficiency High cuz direct Moderate to high High cuz it keeps the Very high cuz it functions like
mechanical link between cuz less efficient due engine in its most fuel- a manual with direct
the engine and wheels, to hydraulic slip in the efficient RPM range. mechanical engagement,
results in less power loss. torque converter and However, can suffer from resulting in minimal power
The driver's skill can power needed to run higher frictional losses in loss. The rapid, seamless
influence efficiency. the hydraulic pump. the belt/pulley system shifts ensure power delivery
under heavy load is almost uninterrupted,
compared to a manual. which also contributes to
efficiency.
Use Used where driver control Used for less complex Used in hybrid vehicles Used in high performance
cases is more required like and easier handling and scooters for high cars for the fastest possible
racing. Used in budget like everyday cars since efficiency and ease of gear shifts and maximum
cars, cuz its cheap. it offers comfortability use. performance.
Used in commercial and ease of use
vehicles cuz high
durability and efficiency.
TASK-2

Spur gear- When two spur gears mesh, the entire face of a tooth meshes with the other gear tooth
at once. This sudden contact creates an impact, which creates a lot of vibration and creates a lot of
noise. Also the whole load is on the one tooth which engaging. This can cause breakage in gears.

Helical gear- when two helical gears mesh, engagement starts at one end of the tooth and gradually
progresses across the face as the gears rotate. This smooth engagement avoids the impact shock of
spur gears, resulting in drastically reduced vibration and noise. The operation is much quieter and
feels smoother to the occupants of the vehicle. When helical gears mesh multiple teeth are in
contact at any given moment. This distributes the load over a larger surface area compared to spur
gears, where typically only one or two pairs of teeth carry the entire load.

Given-

Power = 15 kW = 15000W

Rotational Speed = 1500 RPM therefore w = 157.08

Helix Angle (theta) = 20°

Axial thrust = tangential force *tan(theta)

Tangential force = torque *radius

Therefore axial thrust = (power/w)*radius*tan(theta)

= 34.76*R (R=radius of gear)