新能源新世代 new energy new generation
TRANSCRIPT
新能源新世代
Inspiring Young Minds,
striving for a Greener Hong Kong
New Energy New Generation
”可載人太陽能車”工作坊(二) 車輛動力ABC
28Apr2018
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1) What are the key factors of a rideable solar car ? 2) Are you designing for speed or endurance?
Recap: Essential Question
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a) Rolling Resistance
b) Wind Resistance
c) Acceleration
d) Climbing(Gradient)
Driving forces
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Reducing car power needs
Rolling resistance:
Low weight
Axle bearings
Skinny tires
Winding resistance:
Small frontal area
Smooth shape
Acceleration:
Low weight
Which body shape is fastest?
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Reducing car power needs
Tips on Designing your solar car
52. Reduce friction
1. Reduce frontal area
3. Make the shape smooth
4. Minimize weight
5. Face the sun
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1) Vehicle driving force2) Introduction of Chassis/Rollbar3) Braking system design4) Solar panels development
Contents
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Item Essential Component
1 Bodyshell
2 Chassis and Rollbar
3 Wheels and tires
4 Braking system
5 Safety belts
6 Motor
7 Solar Panel
8 Battery pack
9 Lighting
10 Horn
11 Radio
12 Fire Extinguisher
Before building up the solar car,What have to do first?
Next steps
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Mechanical system
Tires and Rims
Suspension system
Ventilation System
Chassis and
Rollbar
Steering system
Braking system
Mechanical system layout
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Chassis and Rollbar
- Chassis is the significant structure of a car
- A frame with various mechanical parts, like braking , steering, and wheels
- Made of light metal or composite which provides strength needed for supporting vehicle components and load on it
Mechanical system – Chassis and Rollbar
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Monique Chassis
Mechanical system – Chassis and Rollbar
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Recumbent Trike
Braking System
Seat Steering control rod
Remove the pedal and chain
Tires and rims
Mechanical system – Chassis and Rollbar
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SOPHIE SEM
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Dimensions (I)
Total Length
Total Height
WheelbaseGround Clearance
Clearance between the roll bar and helmet
Mechanical system – Chassis and Rollbar
Dimensions (II)
Total Width
Track Width
804
500
Mechanical system – Chassis and Rollbar
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Driver Compartment (w/ Fire Extinguisher)
Wheel Compartment
Battery Compartment
Wheel Bulkhead
Joule meter Compartment
Bulkhead
Mechanical system – Chassis and Rollbar
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CFD Analysis: Wind tunnel
Free app: Wind Tunnel FreeApple Store : https://itunes.apple.com/hk/app/wind-tunnel-free/id381971296?platform=iphone&preserveScrollPosition=true#platform/iphoneGooglePlay:https://play.google.com/store/apps/details?id=com.algorizk.windtunnellite&hl=zh_TW
Mechanical system – Wind tunnel testing
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CFD Analysis: Wind tunnel
Steps: Result:
1) Select ”Draw”
2) Choose effect
3) Calculate
4) Show Result
Mechanical system – Wind tunnel testing
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Dimension requirement
Dimension Limits
Height 100-130cm
Width 120-130cm
Length 220-350cm
Track width 50% of Width
Wheelbase >100cm
Ground clearance
>10cm
Vehicle weight Between 100 and 200 kg
Driver compartment
Height >88cm
Width >70cm
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• Chassis / Monocoque• Must be solid• Wide and long
enough to protect driver
• Roll bar• >50mm above
helmet• extend beyond
shoulders• withstand 70kgf
Roll bar70kgf
Mechanical system – Chassis/Monocoque Stability
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Worksheet 1
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Braking system
- Brake is a mechanical device that inhibits motion by absorbing energy from a moving system.
- It is used for slowing or stopping a moving vehicle, wheel, axle, or to prevent its motion, most often accomplished by means of friction
Mechanical system – Braking system
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Braking System Layout
IndependentBraking System
2Primary Braking
Parking Braking
Ensure the car can STOPmoving! Even one of them FAIL!
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Braking System Layout
- 2 Independent system
- 4 Wheels (2 Front Left, Right Wheels, and 2 Rear Left , Right Wheels)
- Control : Pedal / Brake lever
- Disc / Drum braking
- Hydraulic /Mechanical method
Brake
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Disc / Drum braking
Mechanical system – Braking system
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Hydraulic method
Mechanical system – Braking system
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Mechanical method (Cable Braking)
Mechanical system – Braking system
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Caution: Each system must NOT act only one side of wheels
Wrong connection
Mechanical system – Braking system
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Mechanical system – Braking system design example
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Braking Distance
Initial Conditions and assumption: - 3 Wheels (2 front wheels brake only)- Weight is supported by 3 Wheels evenly- Under flat road, and claim day- Speed: 30km/h (8.33 𝑚/𝑠)- Friction coefficient of tire: 0.7- Reaction time: 0.2 𝑠- Standard gravity: 9.80665 𝑚/𝑠2
Step 1:• Determine the braking deceleration(𝒂𝒃)
𝜇2
3𝑚𝑔 = 𝑚𝑎𝑏
(0.7)2
3𝑚(9.80665) = 𝑚𝑎𝑏
𝑎𝑏 = 4.578 𝑚/𝑠2
Step 2:• Calculation the braking distance (d)
𝑑 =𝑣2
2𝑎𝑏+ 𝑣𝑡𝑟
𝑑 =8.332
2(4.578)+(8.33)(0.2)
𝑑 = 9.25𝑚
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The function of a steering system is to convert the rotary
movement of the steering wheel in driver’s hand into the
angular turn of the front wheels on road.
Mechanical system – Steering system
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Steering System Layout
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Turning radius
tan 𝑏 =𝐻
𝑅 −𝑊2
tan 𝑎 =𝐻
𝑅 +𝑊2
𝑅 +𝑊
2= 8 𝑚𝑒𝑡𝑒𝑟𝑠
Car H(m) W(m) Angle a (deg) Angle b (deg)
Sophie V 2.35 1.4 16.37 19.60
Sophie VI 2.75 1.4 18.97 22.62
Example:
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TailingArmTailing Arm with steering
Suspension System Layout
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Wheel Alignments
Wheel Alignments
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Wheel Alignments
Target Value:
0 ˚ Front
0 ˚ Rear
Camber
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Target Value:
Less than 0.25˚ Front Toe
In
0mm Rear Toe
Toe in/Out
Wheel Alignments
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• Ventilation?
• Doors?
• Visibility? Rear vision?
• Lighting? e.g. head light, indicator light, rear light, brake light, etc.
• Horn
• Etc.
Refer to NENG Rideable Solar Car Regulation 2018
Other considerations
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新能源新世代
Inspiring Young Minds,
striving for a Greener Hong Kong
New Energy New Generation 2018
小休
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Input
Power
Output
Power
Solar cells →Battery pack →motor
Rolling resistance
Wind resistance
Acceleration
Overview
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On-board charging by using solar energy
Solar Panel
DC-DC converter
Main Bus
Battery
Motor Controller
Motor
Solar electric vehicles (Solar EVs)
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Electrical Energy is the presence and flow of an electrical charge, often stored in a battery and usually delivered through a wire in the form of electrons.Example: Electrical energy is stored in car battery
Electrical energy
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Static ElectromagneticElectrochemical reaction
Electrical energy
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Basic ElectricityElectricity has its own set of units. The three most basic in electrical systems are
1) Voltage(V) is the measure of the "push" of electric current. The higher the voltage, the more force there is to push the current through the wire.
2) Amperage(I) is a measure of the amount of electric charge passing a point per unit time.
3) Wattage (W) gives the rate at which work is done or energy is used.
V x I =W
Electrical energy
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Water Pipe Analogy
Think of electricity like plumbing.
Electricity: Not-VisibleWater: Visible
Electrical energy
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Electrical energy
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Ohm’s Law
Resistance is the opposition that a
substance offers to the flow of
electric current.
Electrical energy
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Input power
a) Solar energy
Solar energy
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Working principle of solar cell
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Solar panel
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Experiment
Getting the most power output from a PV panel
• Tilt towards sun
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Experiment
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Incidence angle
Experiment
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Experiment
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Experiment
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Where is the sun?
Experiment
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On May 20 the sun will rise to around 70 degrees
at solar noon (1 p.m.).
Where is the sun?
Experiment
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Solar Panel Connections
Solar panel
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Solar Cell V-I characteristic curve
Solar panel
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Calculate the Poweroutput from thissolar array.
Example
Solar panel
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Find Solar array voltage:
1 series:
1 cell voltage:
= 0.5V
3 cell on 1 series:
= 3 x 0.5 V
=1.5 V
Example
Solar panel
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Find Solar array current:
3 parallels:
= 5 x 3 A
=15 A
Example
Solar panel
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Find Solar array power:
Voltage x Current
= 1.5 x 15
= 22.5 W
Example
Solar panel
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Time to take action: Design your car and Get the car parts!!!
Chassis, Braking, Solar Panel, Battery pack, Motor…….
Next step
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1) What is the surface of the race like?2) How can you design your car to be aerodynamic?3)What tools might be needed in order to make your design?
Essential Question
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Inspiring Young Minds,
striving for a Greener Hong Kong
完
新能源新世代
New Energy New Generation 2018