1. Systems Realization Laboratory How Does A Car Work? Chris Paredis G.W. Woodruff School of Mechanical Engineering Georgia Institute of Technology

2. Systems Realization Laboratory Learn More about Cars The graphical material in this lecture is copied from www.howstuffworks.com www.howstuffworks.com You can find much additional information at this web-site

3. Systems Realization Laboratory Car Sub-Systems of Interest Torque Converter Engine Transmission Differential Tires Car Body

4. Systems Realization Laboratory Engine

5. Systems Realization Laboratory Four Cycles IntakeCompressionCombustionExhaust

6. Systems Realization Laboratory Simplified Engine Model Use SI units! Torque in [Nm], velocity in [rad/s] and Power in [W]

7. Systems Realization Laboratory Car Sub-Systems of Interest Torque Converter Engine Transmission Differential Tires Car Body

8. Systems Realization Laboratory Torque Converter

9. Systems Realization Laboratory Torque Converter The model of a torque converter is fairly complex and highly nonlinear We will not consider it in this class. If you need it, it will be provided to you as a Matlab function.

10. Systems Realization Laboratory Car Sub-Systems of Interest Torque Converter Engine Transmission Differential Tires Car Body

11. Systems Realization Laboratory Transmission Purpose: provide large power at all vehicle velocities

12. Systems Realization Laboratory Transmission more compact sun planet ring

13. Systems Realization Laboratory Model of a Transmission Assumptions: No friction or other losses No inertia Reduces the rotational velocity: Increases the torque where n is the transmission ratio and subscript in refers to the shaft connected to the torque converter.

14. Systems Realization Laboratory Car Sub-Systems of Interest Torque Converter Engine Transmission Differential Tires Car Body

15. Systems Realization Laboratory Differential

16. Systems Realization Laboratory Model of a Differential – Same as Transmission Assumptions: Car drives in a straight line No friction or other losses; no inertia Reduces the rotational velocity: Increases the torque where n is the transmission ratio and subscript in refers to the shaft connected to the transmission.

17. Systems Realization Laboratory Model of a Wheel Assumptions: Car drives in a straight line No slip; no tire deformation; no friction losses; no inertia Converts rotational velocity into translational velocity: Converts torque into force: where R is the radius of the wheel.

18. Systems Realization Laboratory Model of the Car Body Wind Resistance: Gravitational Force: Tire Resistance:

19. Systems Realization Laboratory Putting It All Together

20. Systems Realization Laboratory Examples of Other Models in Vehicle Design Computational Fluid Dynamics Noise, Vibration, and Harshness Crash TestingThermal Stress Analysis