Course Project: Transmission Gearbox Design

Project Description

Choose one of the following gearbox design problems

  1. Design a conventional 2-speed gearbox for best 0-60 acceleration performance
  2. Design a gearbox for a hybrid bus with a parallel architecture for the best fuel economy on FTP-75.

To preview, Prob. 1 involves more complicated gearbox design, and Prob. 2 requires you to learn more about HEV powertrain design and optimal control.

Specifications

The list of design specifications will be the following. You will need to fill in the bold parts through your preliminary report.

  1. Weight and size - As small as possible
  2. Material - Please study materials used for vehicle transmissions elements: gears, shafts, keys, and bearings
  3. Gear ratio - Gear ratios should be set to optimize the objectives (acceleration for Prob. 1 or fuel economy of Prob. 2)
  4. Weak link - Design the keys as the weak link of the gearbox, i.e., if anything would fail, it would be the keys in order to protect other parts
  5. Engine/Motor inputs - For Prob. 1, define the engine max. torque curve and speed range; for Prob. 2, define both the engine and motor max. torque curves, efficiency maps, and speed ranges.
  6. Life - 10 years continuous operation
  7. Reliability - 99% for all parts
  8. Factor of safety - Keys and shafts: n = 2; Bearing fatigue and static: n = 1; Gears surface fatigue: n = 1.2; Gears bending fatigue: n = 1.5; Others: n = 2.

Project Deliverables

Preliminary report (due on April 4)

In the preliminary report, please include the following information.

Prob. 1:

  1. A schematic of a 2-speed gear box, with all elements included and numbered (gears, shafts, bearings, and keys)
  2. A chosen engine represented by the max. torque curve and the rpm range
  3. A chosen vehicle model represented by all necessary parameters for calculating the 0-60 acceleration performance. This may include wheel radius, ground friction, and vehicle weight.
  4. A free body diagram and the analysis that converts an engine torque into a vehicle acceleration value.
  5. An initial program for calculating 0-60 based on settings from 2, 3, and 4. This post might be helpful.

Prob. 2:

  1. A schematic of a parallel architecture for HEV, with all elements included and numbered (gears, shafts, bearings, and keys)
  2. A chosen engine represented by the max. torque curve, the rpm range, and the efficiency map
  3. A chosen motor represented by the max. torque curve, the rpm range, and the efficiency map
  4. A chosen vehicle model represented by all necessary parameters for calculating the 0-60 acceleration performance. This may include wheel radius, ground friction, vehicle weight, coefficient of drag, etc.
  5. A description on how the control strategy (engage and disengage of the motor) is determined. Please read the following paper for reference: Paganelli (2002)

Note: I will upload data and model files (engine, motor, optimal control module) after your preliminary report is due. However, using your own data and writing your own code will be strongly encouraged.

Instructions on Submissions

  1. Please submit a single PDF with the exact title MEE342 %project% where %project% is “Preliminary” or “Final” to Canvas.

  2. I will only grade the final report.