An Investigation of Tire Inflation Pressure on Fuel Consumption for Off-Road Vehicles

This paper presents a comprehensive investigation aimed to assess the effect of tire inflation pressure on the fuel consumption of a typical 4×4 off-road vehicle over unprepared soft terrains. For this purpose, a fourteen-degrees-of-freedom (14-DOF) full parametrized vehicle model is employed and numerically simulated in MATLAB/Simulink™ environment. This model is intended to consider all the rotational dynamics and compliances of all-wheel-drivetrain aggregates using SimDriveline™ toolbox including engine, transmission, differentials, shafts and wheels. Numerous simulations are carried out to examine both the tractive efficiency and fuel consumption considering all power losses in transmission, terrains and tire slippage over different operating conditions such as terrain’s mechanical properties, tire weight distribution and drivetrain configurations (open or locked center differential). Furthermore, the fuel consumption is evaluated during two separate driving scenarios namely; maximum drawbar-pull and Heavy Heavy-Duty Diesel Truck (HHDDT) drive cycle. Simulation results showed that, tire inflation pressure is significantly affecting both the tractive efficiency and fuel economy of the vehicle over unprepared terrains. As a conclusion, tire inflation pressure is controlling both the shape and the forces of tire-terrain contact area and accordingly is dominating the dynamic balance between the applied driving torque from engine and the resisting moments from terrain which in turn affecting engine fuel consumption.