(1) Performance Figure 1 shows a small SUV. The vehicle has a mass of 1480 kg,...

Transcribed Image Text:

(1) Performance Figure 1 shows a small SUV. The vehicle has a mass of 1480 kg, drag coefficient of 0.36, approximate frontal area of 2.5 m, wheelbase of 2.615 m, track width of 1.530 m, and tire rolling radius of 0.3 m. The vehicle has all-wheel-drive and a manual transmission having a manual gearbox gear ratio of 2.062 in second gear, 1.448 in third gear, and a final drive ratio of 4.111. The torque and power characteristics of the vehicle's engine are provided in Table 1. The overall driveline efficiency can be taken to be 85%. At the time of interest, the vehicle is climbing a 5% grade, in still air, on dry pavement having a coefficient of road adhesion of 0.90. Consider the case where the vehicle is operating with an engine speed of 4400 rpm in third gear. For simplicity, consider the longitudinal slip to be 4% throughout the problem solution, the coefficient of rolling resistance to be 0.018, the mass factor for acceleration to be 1.06, and the density of air to be 1.23 kg/m. Figure 1: Small SUV. Table 1: Engine characteristics. ne, rpm 1150 1500 2000 2500 3000 Pe, kW 26.0 34.0 46.7 58.8 71.3 Me, Nm 186.3 200.7 213.1 218.5 223.1 3500 4000 4500 5000 5500 6000 6450 84.3 96.5 106.4 117.0 125.9 127.4 125.9 228.7 230.4 230.5 224.3 218.2 199.6 183.9 (a) Determine the forward vehicle speed. (b) Determine the maximum achievable vehicle acceleration. (c) If operating at constant speed, determine the reserve power. (d) Using the geometric progression method, determine appropriate manual gearbox gear ratios for the first, fourth, and overdrive gears. (1) Performance Figure 1 shows a small SUV. The vehicle has a mass of 1480 kg, drag coefficient of 0.36, approximate frontal area of 2.5 m, wheelbase of 2.615 m, track width of 1.530 m, and tire rolling radius of 0.3 m. The vehicle has all-wheel-drive and a manual transmission having a manual gearbox gear ratio of 2.062 in second gear, 1.448 in third gear, and a final drive ratio of 4.111. The torque and power characteristics of the vehicle's engine are provided in Table 1. The overall driveline efficiency can be taken to be 85%. At the time of interest, the vehicle is climbing a 5% grade, in still air, on dry pavement having a coefficient of road adhesion of 0.90. Consider the case where the vehicle is operating with an engine speed of 4400 rpm in third gear. For simplicity, consider the longitudinal slip to be 4% throughout the problem solution, the coefficient of rolling resistance to be 0.018, the mass factor for acceleration to be 1.06, and the density of air to be 1.23 kg/m. Figure 1: Small SUV. Table 1: Engine characteristics. ne, rpm 1150 1500 2000 2500 3000 Pe, kW 26.0 34.0 46.7 58.8 71.3 Me, Nm 186.3 200.7 213.1 218.5 223.1 3500 4000 4500 5000 5500 6000 6450 84.3 96.5 106.4 117.0 125.9 127.4 125.9 228.7 230.4 230.5 224.3 218.2 199.6 183.9 (a) Determine the forward vehicle speed. (b) Determine the maximum achievable vehicle acceleration. (c) If operating at constant speed, determine the reserve power. (d) Using the geometric progression method, determine appropriate manual gearbox gear ratios for the first, fourth, and overdrive gears.

Answer rating: 100% (QA)

a First we need to calculate the forces acting on the vehicle Gravitational force on the slope Fg... View the full answer