Embedded Files
Electromechanical Systems
Total Model Mass
Factor of Safety Weight = 375 lbs
Total Weight = 485.69 lbs
For 1 Full Charge of atleast 25 miles of total riding:
2 x 24V/10Ah batteries in Parallel (keeps voltage same, adds current)
2 x 24V/3.8Ah batteries in Parallel (keeps voltage same, adds current)
1 Hour of usage (24V/20Ah Batteries = 480 Wh) + (24V/7.6Ah Batteries = 182.4 Wh) = Total Battery Capacity = 662.4 Wh
2 x 24V/1 HP DC motors = 750 Watts/ motor, 1500 Wh total
Required Motor Torque Wh = 360.426 Watts
12V/2.91A Bulb = 35 Wh
2 x Bulbs = 70 Wh
12V/2.1A Charger = 25.2 Wh
12V/1.5A Horn = 18 Wh
12V LCD User Interface = 1.3 Wh
Power Usage: 361.767 + 70 + 25.2 + 18+ 1.3 = 476.267 Wh
Battery Capacity > Power Consumption by 186.133 Wh
NOTE: Assuming constant 25 mph velocity on a straight path with constant power consumption for 1 hour.
Suspension Systems
(ASSUME ALL SUSPENSIONS EQUALLY SHARE THE WEIGHT PERPENDICULARLY TO THE GROUND ATTACHED TO THE MIDDLE OF THE WHEELS)
MAX LOAD
MAX Weight = 478.08 lbs
F=MA = -478.08 lbs
F=-4KX
KX = 119.52 lbs
X = 4 inches, 1/3 ft
K = 358.56 lbs/ft
From the results above, the each spring should support 119.52 lbs of force including factor of safety of 1.5. Spring deflection, variable X, is 4 inches to clear obstacles and potholes to support more comfortable ride. Spring constant is 358.56 lbs/ft.
A VIABLE SPRING OPTION FOR THE FRONT WHEEL FOR MAX LOAD
PC137-938-36500-MW-11100-CG-N-IN
Outer Diameter = 0.938 in
Inner Diameter = 0.664 in
Free Length = 11.100 in
Solid Height = 5.001 in
Wire Diameter = 0.137 in
Total Coils = 36.500
Rate = 28.544 lbs/in
Max Load = 121.798 lbs
Max Deflection = 4.267 in
Material Type = MW
PC137-938-36500-MW-11100-CG-N-IN is picked for the front suspensions. The suspensions for the front wheel should have longer and larger free length and max deflection than the back wheels suspensions to support more ground clearance while riding.
A VIABLE SPRING OPTION FOR THE BACK WHEELS FOR MAX LOAD
PC192-1937-10800-SST-5500-CG-N-IN
Outer Diameter = 1.937 in
Inner Diameter = 1.553 in
Free Length = 5.500 in
Solid Height = 2.074 in
Wire Diameter = 0.192 in
Total Coils = 10.800
Rate = 36.145 lbs/in
Max Load = 123.847 lbs
Max Deflection = 3.426 in
Material Type = SST 302
PC192-1937-10800-SST-5500-CG-N-IN is selected for the back suspensions. The suspensions for the back wheels should have shorter free length and max deflection than the front wheel because there is less space in the rear due to components such as: motors, battery, etc. The back suspensions should carry more max load to support the passenger and equipments as well.
Steering
Three Wheeled System Steering With 2 wheels In The Rear Axle
Steering Angle ᵟ remains equal for all wheels
W = Wheelbase = 39 Inches
r1 = Turning Radius of Leftwheel
r2 = Turning Radius of Rightwheel
All Follow Circle Path about the same circular origin
Stability
Tipping Angle of the Vehicle
TR (WB - LG) / 2 (WB) (HG) = F_c
F_c = TAN (tip angle)
TR = 20 in, 1.667 ft
WB = 39 in, 3.25 ft
LG = 25.47 in, 2.1225 ft
HG = 12.46 in, 1.03833 ft
F_c = 0.278429
Tip Angle = 15.5587 degrees
The vehicle should have an tip angle of less than 15.5587 degrees in order to be statically stable while making turns.
Braking System
The vehicle will have a total of 3 wheels with 1 in the front and 2 in the rear.
All of the wheels will be identical and the brakes will be applied in the same way on each wheel.
Attached to each wheel is a brake disc which will have a caliper on each disc.
The calipers will be applied to the disc by brake cables and the rear two wheels will be connected as shown in the diagram.
The front wheel will also have a caliper connected to brake cables and will be independent from the rear brakes.
Page updated
Report abuse