Design Overview
FutureTruck 2000
The FutureTruck 2000 project is a collegiate competition organized by the U.S. Department of Energy and General Motors Corporation. The primary objective is to modify a 2000 Suburban to increase the fuel economy (energy efficiency) as measured by the total greenhouse gas impact. The University of Idaho approach is to convert the vehicle to a series hybrid while maintaining vehicle functionality without compromising the safety, convenience and performance consumers expect. Gear Engineering And Reduction Systems (GEARS) is a senior design team whose primary focus is to develop a drivetrain for the University of Idaho FutureTruck.
Speed Reducer Concept
The high electric motor speed (7000-12000rpm) is converted to a low transmission input speed (1000-3000rpm) through a star speed reducer. This reduction multiplies the electric motor torque by 2.5. With input speeds and torque similar to that of the stock gasoline engine, the rest of the drivetrian was left unchanged. The Suburban then operates and shifts much like a standard vehicle.
Pro/Engineer Model
Design Overview
The design goals for the FutureTruck drivetrain are to accelerate 0-60 mph in less than 12 seconds and to maintain a minimum speed of 55 mph pulling a 7000 lb trailer up a 5% grade. GEARS developed an acceleration model to determine the gear ratio necessary to meet the performance goals. Universal Technical Systems software was used to size the gear set based on the determined gear ratio, required torque, and electric motor speeds. Pro/Engineer models were then developed to support fabrication of the design. Although the gear set was manufactured professionally, the rest of the system was machined in the University of Idaho Mechanical Engineering Shop.
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GEARS members Klaus Johnson (left) and Eric Clarke (right) with the converted drivetrain
Performance Modeling Results
• 0-60 mph acceleration in 10.79 sec
• Top speed of 60 mph while towing a 7000 lb trailer up a 5% grade
0-60mph acceleration showing shift points Pulling a Trailer up a 5% Grade
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Acceleration model results for the Future Truck used to optimize gear ratios and transmission shift points.
Road Load model results for the Future Truck towing a 7000 lb trailer. Where the two curves intersect is the predicted top speed.
Drive Train Specifications
|Transmission |Speed Reduction |
|GM 4L60E |2.5 : 1 Total |
|Gear Ratios |Gear Design Standards |
|1st gear 3.06 |10 inch pitch |
|2nd gear 1.63 |20 degree pressure angle |
|3rd gear 1.0 |1.75 face width |
|4th gear 0.7 |Ring Gear Teeth |
| |60 |
|Electrical Isolation |Planet Gear Teeth |
|Phenolic Disk |18 |
|Transfer Case NGB246 |Sun Gear Teeth |
| |24 |
|Transmission Control |Max Input Speed |
|TCI Computer |8000 rpm |
| |Max Output Speed |
| |3200 rpm |
| |Max Input Torque |
| |165 lb*ft |
| |Max Output Torque |
| |412.5 lb*ft |
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