Tire Warmup Relation to Rolling Resistance: Understanding how rolling resistance affects and is affected by tire temperature in realistic driving scenario
Typ
Examensarbete för masterexamen
Master's Thesis
Master's Thesis
Program
Mobility engineering (MPMOB), MSc
Publicerad
2024
Författare
Kolekar, Abhishek Amit
Madhuravasal Narasimhan, Vivekanandan
Modellbyggare
Tidskriftstitel
ISSN
Volymtitel
Utgivare
Sammanfattning
The automotive sector is committed to advancing energy efficiency by providing
customers with sustainable transportation solutions. With the increasing adoption
of electric vehicles with high powertrain efficiency but limited range, reducing other
forms of losses, such as rolling resistance, is important. Rolling Resistance (RR)
typically contributes around 25% of the energy loss in Electric Vehicles (EVs) [1].
The current measurement of the tire’s rolling resistance is obtained at steady state,
which rarely occurs in real-world driving conditions that involve frequent starts and
stops, preventing the tire from reaching a steady state equilibrium.
This thesis focuses on the effect of warmup on the rolling resistance of tires differing
only by their aspect ratios, focusing on measuring and calculating rolling resistance
under realistic conditions. The variation of the tire temperature and rolling resistance is measured during both the warmup (transient) and the steady state on the
tire test rig by varying the inflation pressure, speed, and normal load for different
tires. The rolling resistance showed a negative correlation with the inflation pressure, a positive correlation with the speed, and no correlation to the load.
Using the data obtained in the warmup region, a rolling resistance model is created
that uses temperature and speed as inputs to calculate the instantaneous rolling
resistance. A thermal tire model is also developed that can predict the internal
temperature of the tire based on the rolling resistance and speed. Using drive cycle
tests, the models were validated, and it was observed that the rolling resistance of
the tires varied dramatically through the cycle and rarely matched the ISO standard rolling resistance value. Depending on the tire, it was found that the transient
rolling resistance was 25-30% higher before reaching a steady state value.
Data from the drive cycle test was used to calculate the rolling energy loss using
both the ISO standard rolling resistance coefficient & the rolling resistance model
developed. It was found that the rolling energy loss can vary from 6 to 22% between
the two approaches, which provides a better understanding of the transient behavior
of rolling resistance with respect to a complex drive cycle. This enables better
insights into the contribution of rolling resistance to the overall energy loss, and the
tire selection process can be made more effective.
Beskrivning
Ämne/nyckelord
rolling resistance , tire warmup , modeling , transient rolling energy loss