howdoesacarwork.ppt
TRANSCRIPT
![Page 1: HowDoesACarWork.ppt](https://reader035.vdocuments.mx/reader035/viewer/2022070412/55cf905b550346703ba524b6/html5/thumbnails/1.jpg)
Systems Realization Laboratory
How Does A Car Work?
Chris Paredis
G.W. Woodruff School of Mechanical Engineering
Georgia Institute of Technology
![Page 2: HowDoesACarWork.ppt](https://reader035.vdocuments.mx/reader035/viewer/2022070412/55cf905b550346703ba524b6/html5/thumbnails/2.jpg)
Systems Realization Laboratory
Learn More about Cars
The graphical material in this lecture is copied from www.howstuffworks.com
You can find much additional information at this web-site
![Page 3: HowDoesACarWork.ppt](https://reader035.vdocuments.mx/reader035/viewer/2022070412/55cf905b550346703ba524b6/html5/thumbnails/3.jpg)
Systems Realization Laboratory
Car Sub-Systems of Interest
Torque Converter
Engine
Transmission
Differential
Tires
CarBody
![Page 4: HowDoesACarWork.ppt](https://reader035.vdocuments.mx/reader035/viewer/2022070412/55cf905b550346703ba524b6/html5/thumbnails/4.jpg)
Systems Realization Laboratory
Engine
![Page 5: HowDoesACarWork.ppt](https://reader035.vdocuments.mx/reader035/viewer/2022070412/55cf905b550346703ba524b6/html5/thumbnails/5.jpg)
Systems Realization Laboratory
Four Cycles
Intake Compression Combustion Exhaust
![Page 6: HowDoesACarWork.ppt](https://reader035.vdocuments.mx/reader035/viewer/2022070412/55cf905b550346703ba524b6/html5/thumbnails/6.jpg)
Systems Realization Laboratory
Simplified Engine Model
1000 2000 3000 4000 5000 6000 7000 80000
50
100
150
200
250
300
350
400
450
Speed [RPM]P
ower
[kW
]
Engine Power as a function of Engine Speed
Chevy 4-cyl 1.8LFord 6cyl 3LPorsche 8cyl 5.4L
1000 2000 3000 4000 5000 6000 7000 80000
50
100
150
200
250
300
350
400
450
Speed [RPM]
Pow
er [
kW]
Engine Power as a function of Engine Speed
Chevy 4-cyl 1.8LFord 6cyl 3LPorsche 8cyl 5.4L
1000 2000 3000 4000 5000 6000 7000 80000
50
100
150
200
250
300
350
400
450
Speed [RPM]
Pow
er [
kW]
Engine Power as a function of Engine Speed
Chevy 4-cyl 1.8LFord 6cyl 3LPorsche 8cyl 5.4L
1000 2000 3000 4000 5000 6000 7000 80000
200
400
600
800
1000
1200
1400
Speed [RPM]
Tor
que
[Nm
]
Engine Torque as a function of Engine Speed
Chevy 4-cyl 1.8LFord 6cyl 3LPorsche 8cyl 5.4L
1000 2000 3000 4000 5000 6000 7000 80000
50
100
150
200
250
300
350
400
450
Speed [RPM]
Pow
er [
kW]
Engine Power as a function of Engine Speed
Chevy 4-cyl 1.8LFord 6cyl 3LPorsche 8cyl 5.4L
1000 2000 3000 4000 5000 6000 7000 80000
50
100
150
200
250
300
350
400
450
Speed [RPM]
Pow
er [
kW]
Engine Power as a function of Engine Speed
Chevy 4-cyl 1.8LFord 6cyl 3LPorsche 8cyl 5.4L
1000 2000 3000 4000 5000 6000 7000 80000
200
400
600
800
1000
1200
1400
Speed [RPM]
Tor
que
[Nm
]
Engine Torque as a function of Engine Speed
Chevy 4-cyl 1.8LFord 6cyl 3LPorsche 8cyl 5.4L
1000 2000 3000 4000 5000 6000 7000 80000
200
400
600
800
1000
1200
1400
Speed [RPM]
Tor
que
[Nm
]Engine Torque as a function of Engine Speed
Chevy 4-cyl 1.8LFord 6cyl 3LPorsche 8cyl 5.4L
1000 2000 3000 4000 5000 6000 7000 80000
200
400
600
800
1000
1200
1400
Speed [RPM]
Tor
que
[Nm
]
Engine Torque as a function of Engine Speed
Chevy 4-cyl 1.8LFord 6cyl 3LPorsche 8cyl 5.4L
1000 2000 3000 4000 5000 6000 7000 80000
200
400
600
800
1000
1200
1400
Speed [RPM]
Tor
que
[Nm
]
Engine Torque as a function of Engine Speed
Chevy 4-cyl 1.8LFord 6cyl 3LPorsche 8cyl 5.4L
1000 2000 3000 4000 5000 6000 7000 80000
200
400
600
800
1000
1200
1400
Speed [RPM]
Tor
que
[Nm
]
Engine Torque as a function of Engine Speed
Chevy 4-cyl 1.8LFord 6cyl 3LPorsche 8cyl 5.4L
( )f P
Use SI units! Torque in [Nm], velocity in [rad/s] and Power in [W]
![Page 7: HowDoesACarWork.ppt](https://reader035.vdocuments.mx/reader035/viewer/2022070412/55cf905b550346703ba524b6/html5/thumbnails/7.jpg)
Systems Realization Laboratory
Car Sub-Systems of Interest
Torque Converter
Engine
Transmission
Differential
Tires
CarBody
![Page 8: HowDoesACarWork.ppt](https://reader035.vdocuments.mx/reader035/viewer/2022070412/55cf905b550346703ba524b6/html5/thumbnails/8.jpg)
Systems Realization Laboratory
Torque Converter
![Page 9: HowDoesACarWork.ppt](https://reader035.vdocuments.mx/reader035/viewer/2022070412/55cf905b550346703ba524b6/html5/thumbnails/9.jpg)
Systems Realization Laboratory
Torque Converter
The model of a torque converter is fairly complex and highly nonlinearWe will not consider it in this class.
If you need it, it will be provided to you as a Matlab function.
![Page 10: HowDoesACarWork.ppt](https://reader035.vdocuments.mx/reader035/viewer/2022070412/55cf905b550346703ba524b6/html5/thumbnails/10.jpg)
Systems Realization Laboratory
Car Sub-Systems of Interest
Torque Converter
Engine
Transmission
Differential
Tires
CarBody
![Page 11: HowDoesACarWork.ppt](https://reader035.vdocuments.mx/reader035/viewer/2022070412/55cf905b550346703ba524b6/html5/thumbnails/11.jpg)
Systems Realization Laboratory
Transmission
Purpose: provide large power at all vehicle velocities
0 50 100 150 200 250 300 350 4000
50
100
150
200
250
Velocity [kmh]
Pow
er [
kW]
Power at the drive shaft for different gear ratios
![Page 12: HowDoesACarWork.ppt](https://reader035.vdocuments.mx/reader035/viewer/2022070412/55cf905b550346703ba524b6/html5/thumbnails/12.jpg)
Systems Realization Laboratory
Transmission
morecompact
sunplanet ring
![Page 13: HowDoesACarWork.ppt](https://reader035.vdocuments.mx/reader035/viewer/2022070412/55cf905b550346703ba524b6/html5/thumbnails/13.jpg)
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.
inout n
out in n
![Page 14: HowDoesACarWork.ppt](https://reader035.vdocuments.mx/reader035/viewer/2022070412/55cf905b550346703ba524b6/html5/thumbnails/14.jpg)
Systems Realization Laboratory
Car Sub-Systems of Interest
Torque Converter
Engine
Transmission
Differential
Tires
CarBody
![Page 15: HowDoesACarWork.ppt](https://reader035.vdocuments.mx/reader035/viewer/2022070412/55cf905b550346703ba524b6/html5/thumbnails/15.jpg)
Systems Realization Laboratory
Differential
![Page 16: HowDoesACarWork.ppt](https://reader035.vdocuments.mx/reader035/viewer/2022070412/55cf905b550346703ba524b6/html5/thumbnails/16.jpg)
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.
inout n
out in n
![Page 17: HowDoesACarWork.ppt](https://reader035.vdocuments.mx/reader035/viewer/2022070412/55cf905b550346703ba524b6/html5/thumbnails/17.jpg)
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.
car wheelv R
wheelcarF R
![Page 18: HowDoesACarWork.ppt](https://reader035.vdocuments.mx/reader035/viewer/2022070412/55cf905b550346703ba524b6/html5/thumbnails/18.jpg)
Systems Realization Laboratory
Model of the Car Body
Wind Resistance:
Gravitational Force:
Tire Resistance:
21( )
2drag d carF C A v
sin( )gravF mg
cos( )rolling rF mg
gravF
mg
rollingF
dragF
cos( )mg
![Page 19: HowDoesACarWork.ppt](https://reader035.vdocuments.mx/reader035/viewer/2022070412/55cf905b550346703ba524b6/html5/thumbnails/19.jpg)
Systems Realization Laboratory
Putting It All Together
1000 2000 3000 4000 5000 6000 7000 8000 9000 100000
50
100
150
200
250
300
engine speed in rpm
torq
ue
in [
Nm
]
Engine and Load Torques for a 10% Slope
engine torqueload torque (1st)load torque (2nd)load torque (3rd)load torque (4th)load torque (5th)
![Page 20: HowDoesACarWork.ppt](https://reader035.vdocuments.mx/reader035/viewer/2022070412/55cf905b550346703ba524b6/html5/thumbnails/20.jpg)
Systems Realization Laboratory
Examples of Other Models in Vehicle Design
Computational Fluid Dynamics
Noise, Vibration,and Harshness
Crash TestingThermalStress Analysis