Chapter9 Operational Performance Section 1 Dynamic Property 1.Automobiles'Dynamic Property 1.1 Automobiles'Maximum Speed Vamax(km/h) It refers to the highest speed that automobile can reach on roads in good condition(concrete or asphalt roads). 1.2 Automobiles'Acceleration Time t(s) (1)Standing start acceleration time is the required time that gradual changing automobile gears from I gear to high gear with the greatest acceleration and reaching a predetermined distance or speed It usually represent as the time that automobiles cost to travel 400m or reach the speed of 80.5km/h. (2)Overtaking acceleration time is the required time that automobiles reach a certain high speed from a moderate speed at the top gear or second top gear with the highest acceleration. 机械电子工程学度 《汽车拖拉机学》 Northwest A&F University
《汽车拖拉机学》 Northwest A&F University Chapter 9 Operational Performance 1. Automobiles’ Dynamic Property 1.1 Automobiles’ Maximum Speed Vamax(km/h) It refers to the highest speed that automobile can reach on roads in good condition(concrete or asphalt roads). 1.2 Automobiles’ Acceleration Time t(s) (1) Standing start acceleration time is the required time that gradual changing automobile gears from I gear to high gear with the greatest acceleration and reaching a predetermined distance or speed. It usually represent as the time that automobiles cost to travel 400m or reach the speed of 80.5km/h. (2) Overtaking acceleration time is the required time that automobiles reach a certain high speed from a moderate speed at the top gear or second top gear with the highest acceleration. Section 1 Dynamic Property
Chapter 9 Operational Performance Section 1 Dynamic Property It commonly represents as the time that automobiles reach a certain high speed from 30km/h or 40km /h at the top gear or the second top gear with the highest acceleration,or use the acceleration curve to reflect the overall acceleration capability. It is dangerous that the two cars travel abreast for a long time when overtaking,so it is more secure if the time is shorter. 1.3 The Maximum Gradeability imax(%) Automobiles'climbing capacity are represented by the maximum gradeability automobiles can reach at I gear on roads in good condition when fully loaded. 机械电子工程模 《汽车拖拉机学》 Northwest A&F University
《汽车拖拉机学》 Northwest A&F University Chapter 9 Operational Performance It commonly represents as the time that automobiles reach a certain high speed from 30km / h or 40km / h at the top gear or the second top gear with the highest acceleration, or use the acceleration curve to reflect the overall acceleration capability. It is dangerous that the two cars travel abreast for a long time when overtaking, so it is more secure if the time is shorter. 1.3 The Maximum Gradeability imax(%) Automobiles’ climbing capacity are represented by the maximum gradeability automobiles can reach at I gear on roads in good condition when fully loaded. Section 1 Dynamic Property
Chapter 9 Operational Performance Section 1 Dynamic Property 2.The Driving Force and Driving Resistance of Automobiles 2.1 Driving Equations of Automobiles Using P to represent the driving force,Pto represent all kinds of driving resistance,then the balance equation is: P,=∑P 2 or Pa =Pr+Pw +P+P 20 2.2 Driving Force 2.3 Figure of Automobiles'Driving Force 2.4 Automobiles'Driving Resistance 40 6080 Va km/h Figure 9-1 Automobiles'driving force 械电子工程学度 《汽车拖拉机学》 Northwest A&F University
《汽车拖拉机学》 Northwest A&F University Chapter 9 Operational Performance 2. The Driving Force and Driving Resistance of Automobiles Pq = P Pq = Pf + PW + Pi + Pj 2.1 Driving Equations of Automobiles Using Pq to represent the driving force, ΣP to represent all kinds of driving resistance, then the balance equation is: or 2.2 Driving Force 2.3 Figure of Automobiles’ Driving Force 2.4 Automobiles’ Driving Resistance Figure 9-1 Automobiles’ driving force Section 1 Dynamic Property
Chapter 9 Operational Performance Section 1 Dynamic Property 3.Equilibrium Figure of Automobiles'Driving Force and Driving Resistance e1.0 10 Pq P+Pw 、C 20406080100 0 20406080 Va km/h Va km/h Figure 9-2 Equilibrium figure of Figure 9-3 Acceleration curve of automobiles'driving force and driving automobiles resistance 业机械持电子工程膜 《汽车拖拉机学》 Northwest A&F University
《汽车拖拉机学》 Northwest A&F University Chapter 9 Operational Performance 3. Equilibrium Figure of Automobiles’ Driving Force and Driving Resistance Figure 9-2 Equilibrium figure of automobiles’ driving force and driving resistance Figure 9-3 Acceleration curve of automobiles Section 1 Dynamic Property
Chapter9 Operational Performance Section 1 Dynamic Property △n 1J2 0 Va Va a) b) Figure 9-4 Curve of the reciprocal of acceleration 业机械电子工学度 《汽车拖拉机学》 Northwest A&F University
《汽车拖拉机学》 Northwest A&F University Chapter 9 Operational Performance Figure 9- 4 Curve of the reciprocal of acceleration Section 1 Dynamic Property
Chapter 9 Operational Performance Section 1 Dynamic Property 60 40 20 20 40 60 80 Va,km/h 0 Va,km/h a) b) Figure 9-5 Automobiles'acceleration time graph (a)Top gear (b)Since 1st gear to the top gear 《汽车拖拉机学》 Northwest A&F University
《汽车拖拉机学》 Northwest A&F University Chapter 9 Operational Performance Figure 9- 5 Automobiles’ acceleration time graph (a) Top gear (b) Since 1st gear to the top gear Section 1 Dynamic Property
Chapter9 Operational Performance Section 1 Dynamic Property imax 40 30 20 10 lomax 20 40 6080 V.,km/h Figure 9-6 Figure of automobiles'gradeability 械电子工程学度 《汽车拖拉机学》 Northwest A&F University
《汽车拖拉机学》 Northwest A&F University Chapter 9 Operational Performance Figure 9-6 Figure of automobiles’ gradeability Section 1 Dynamic Property
Chapter 9 Operational Performance Section 1 Dynamic Property 4.Figure of Automobiles'Dynamic Property 25 0.30 20 0.25 0.20 0.15 0.10 0.05 20 406080V.,km/2 20 4060 Vi.km/h Figure 9-7 the driving force figure of Figure 9-8 Figure of dynamic property of two two different total weight automobiles total weight of two different total weight automobiles 4.1 Dynamic Factor D of automobiles D-B-0+=f+i+8. =0+ G g dt g dt 《汽车拖拉机学》 Northwest A&F University
《汽车拖拉机学》 Northwest A&F University Chapter 9 Operational Performance 4. Figure of Automobiles’ Dynamic Property Figure 9-7 the driving force figure of two different total weight automobiles dt dV g f i dt dV G g P P D q W a a = + = + + − = 4.1 Dynamic Factor D of automobiles Figure 9-8 Figure of dynamic property of two total weight of two different total weight automobiles Section 1 Dynamic Property
Chapter9 Operational Performance Section 1 Dynamic Property 4.2 Fixing the Maximum Speed The maximum speed is the highest speed automobiles can reach on level roads in good condition.At the moment: D=f 4.3 Fixing the Climbing Ability Domax am=si D-f·1-D2a+f Vamax Va 1+f2 4.4 Fixing the Accelerating Ability Figure 9-9 Using dynamic property figure to fix automobiles'dynamic property D=f+ 8 dva g dt da=8(D-f） dtδ 械电子工程学 《汽车拖拉机学》 Northwest A&F University
《汽车拖拉机学》 Northwest A&F University Chapter 9 Operational Performance Figure 9-9 Using dynamic property figure to fix automobiles’ dynamic property 4.2 Fixing the Maximum Speed The maximum speed is the highest speed automobiles can reach on level roads in good condition. At the moment: , D=f 4.3 Fixing the Climbing Ability 2 2 2 1 Im Im max 1 1 sin f D f D f a x a x + − − + = − dt dV g D f a = + (D f ) g dt dVa = − 4.4 Fixing the Accelerating Ability Section 1 Dynamic Property
Chapter 9 Operational Performance Section 2 Fuel Economy Fuel economy is one of the most important usability of the automobile.In automobile transportation costs,fuel costs account for about 20 to 30%. 1.Evaluation Indicators of Automobile Fuel Economy Fuel economy is the ability that automobiles complete the unit of transport workload with the least fuel consumption. Fuel economy of the engine usually use effective fuel consumption rate ge or effective rate ne to evaluate.It can not be used to evaluate fuel economy of the entire car directly because it is not reflect the power utilization of the specific car engine and the impact of driving conditions. In order to evaluate the fuel economy,these two factors mentioned above should be taken into account,so it is usually used fuel consumption of the unit distance of travel,or fuel consumption of the unit of transport workload to represent. 械电子工程 《汽车拖拉机学》 Northwest A&F University
《汽车拖拉机学》 Northwest A&F University Chapter 9 Operational Performance Fuel economy is one of the most important usability of the automobile. In automobile transportation costs, fuel costs account for about 20 to 30%. 1. Evaluation Indicators of Automobile Fuel Economy Fuel economy is the ability that automobiles complete the unit of transport workload with the least fuel consumption. Fuel economy of the engine usually use effective fuel consumption rate ge or effective rate ηe to evaluate. It can not be used to evaluate fuel economy of the entire car directly because it is not reflect the power utilization of the specific car engine and the impact of driving conditions. In order to evaluate the fuel economy, these two factors mentioned above should be taken into account, so it is usually used fuel consumption of the unit distance of travel, or fuel consumption of the unit of transport workload to represent. Section 2 Fuel Economy
