Throttle Pedal + Return Mechanism

High-level Design Goals

· Throttle return - Design the pedal travel and force curve to provide precise control, minimize driver effort, and maximize responsiveness.

· Weight reduction - Optimize for weight while maintaining optimal pedal stiffness and rigidity under heavy loads for precise throttle control and driver confidence.

· Streamlined manufacturing - Implement design and manufacturing techniques to decrease production time and lower associated costs.

· Cost reduction - Utilize cost-effective materials that retain the required strength and stiffness without sacrificing performance.

Concept Testing (First Prototype)

During the concept exploration phase, the parallel plate design emerged as the most promising candidate based on the selection matrix evaluation. To gain further confidence in its viability, a physical prototype was constructed. This prototype utilized a combination of laser-cut plywood for the main structure and 3D-printed sections for the pedal tray itself. The successful creation and testing of this prototype served to validate the parallel plate concept's potential and warranted further exploration in the design process.

2022 (Left) VS 2023 (Right)

B22: The B22 Design was designed for easy manufacturing and assembly using a waterjet. The design incorporated ball bearings for smooth operation and a tension spring return system.

B23: The B23 Design was more optimized for cost and weight while increasing complexity with the parallel plate design. The transition from a ball bearing to a bronze bushing also allowed the incorporation of the torsional spring return system.

Design Validation FEA

Throttle pedal specifications:

Required to take 50lbs of force at the pedal face with a minimum FOS of 2
Required to take 15lbs of force perpendicular to the pivot with a FOS of 1.5

This 50lbf requirement was determined by the measurement of a reasonable force expected to be exerted by a driver during normal operation.

FEA Setup:

50lb force on the pedal face (25lbs since we are simulating one plate)
Remote displacement on the pivot
Frictionless constrain on the hard stop

Torsion Spring Testing Jig

To determine an optimal return force for the pedal, a torsion spring testing jig was designed and fabricated. This jig allowed for the evaluation of different spring strengths, providing valuable data based on driver feedback. The collected data ultimately guided the design of the return mechanism, ensuring it delivers a return force that meets driver preferences.

Manufacturing

Plates were manufactured using a waterjet and holes were post processed using a drill press to the specified tolerance.

Skills Used: Solidworks, Solidworks Simulation, Engineering Drawings with GD&T. Waterjet, Mill, 3D Printing

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