Trunk and Roof Prop and Tilting Project Overview

Owned by Asher L
Last updated: Feb 17, 2021
5 min read

 

Overview

The purpose of this document is to serve as a high level planning and management document for the trunk and roof prop plus tilting project

Introduction

Trunk Prop and Tilting

For MS XIV, it was decided that the trunk panel would open in a conventional manner (as it does on standard production cars).

To allow for tilting of the trunk panel to the side (in order to maximize the amount of solar energy captured when the sun is low / close to the horizon) it was decided that the trunk panel would be detached and placed onto an accessory tilting structure.

Roof Prop and Tilting

For MS XIV, it was decided that the roof panel would be able to tilt to the side for the same reason as the trunk panel.

To achieve this, either an integrated method (where the roof is hinged to the chassis) or a separated method (where the roof would be detached from the chassis before tilting) could be pursued.

It was decided that if a feasible integrated method was possible then it would be preferable due to its ease of use and operation.

Problem - Trunk Prop and Tilting

Functional Requirements

The assembly of components that make up the trunk prop and tilting system must:

  • Support the trunk when it is fully opened

    • Trunk weight plus force of wind on the trunk panel

  • Allow for the trunk panel to be closed by a user

    • Without requiring levels of force that would be harmful to the user or the panel itself

  • Support the ability for the trunk panel to be detachable

  • Tilt the trunk sideways when it has been detached

  • Be compatible with the trunk hinge and latches

Non-functional Requirements

The assembly of components that make up the trunk prop and tilting system should:

  • Be easily manufacturable

    • Preferably in-house, but can also be done by outside suppliers

  • Present low risk and be feasible to implement

  • Be as user friendly as possible

  • Be as lightweight as possible

  • Be as cost-effective as possible

Scope - Trunk Prop and Tilting

Overview

Research

  • Trunk Prop Rods

  • Determining trunk prop mounting locations

    • i.e. How to mount the trunk prop such that it will obtain the desired range of motion for the trunk while being able to support its weight

  • Trunk Prop Mounting Methods / Styles

  • Design for Adhesives for Mounting Brackets

  • Trunk Tilting Structure

    • Methods to do it

    • Placing it inside vs outside the car

 

Concepting and Initial Design

  • Mounting Bracket - to Chassis

  • Mounting Bracket - to Trunk Panel

  • Additional Tilting Structure

  • Trunk Prop

 

Testing and Validation

  • Hand calculations

    • Determine if trunk prop can actually support trunk panel

  • FEA

    • Ensure mounting brackets will be properly attached to chassis / trunk panel

      • More of a concern with adhesive based mounting methods

    • Ensure mounting brackets are designed so that they won’t yield / deform

    • Ensure chassis tube we mount to will not yield / deform

    • Ensure accessory tilting structure can securely hold in place the trunk panel

  • Motion Study

    • Ensure trunk props can account for motion of the trunk panel

      • Ensure the motion is continuous

 

Detailed Design

  • Mounting locations and methods for brackets finalized

  • Additional tilting mechanism placement (inside vs outside the car) finalized

  • Proper trunk prop has been specified

    • Both length and rated force

  • DFM and DFA verification

    • If needed to be made outside, connecting with SI to see if there are available suppliers

  • Manufacturing Drawings

 

Manufacturing

  • Mounting Brackets

  • Additional Tilting Mechanism (may be a sub-assembly - TBD)

 

Integration

  • Mounting brackets to: chassis, trunk panel

  • Fastening trunk prop to mounting brackets

  • Additional tilting mechanism either: mounted to or stored within the car

 

Problem - Roof Prop and Tilting

Functional Requirements

The assembly of components that make up the roof prop and tilting system must:

  • Support the roof when it is fully opened

    • Roof weight plus force of wind on the roof panel

  • Tilt the roof to the side

    • In such a way it does not: collide with other panels, or put undue levels of stress on the roof panel

  • Be compatible with roof panel fastening methods

Non-functional Requirements

The assembly of components that make up the trunk prop and tilting system should:

  • Be easily manufacturable

    • Preferably in-house, but can also be done by outside suppliers

  • Present low risk and be feasible to implement

  • Be as user friendly as possible

  • Be as lightweight as possible

  • Be as cost-effective as possible

 

 

 

 

Scope - Roof Prop and Tilting

Overview

Research

  • Roof Prop Rods

  • General Roof Tilting Methods

    • Hinge and hinge-less designs

  • Roof Hinge Designs and Feasibility

    • Roof Hinge Mounting Locations

  • Roof Hinge Mounting

  • Design for Adhesives for Mounting Brackets

 

Concepting and Initial Design

  • Mounting Bracket - to Chassis

  • Mounting Bracket - to Roof Panel

  • Hinge Mounting

  • Roof Prop

  • Roof Hinge

 

Testing and Validation

  • Hand Calculations

    • For geometry of roof hinge and mounting brackets

    • For roof hinge mounting method

      • Ensuring roof hinge will be securely mounted and stationary as it is expected to be

    • For attachment method for mounting brackets

    • For roof prop to ensure it can withstand bending and compression loads

  • FEA

    • Same scenarios as above

      • May give more accurate results, potentially with attachment method for mounting brackets (fasteners, adhesives)

  • Motion Study

    • Ensure roof hinge will articulate roof panel in the desired motion

      • No collision with other panels

      • Able to tilt to desired angle

  • Scaled Down Prototype

    • Can create a scaled down prototype using scrap materials / 3D Printed parts

      • Go through motion in real life to ensure Motion Study captured all variables

 

Manufacturing

  • Mounting Brackets

  • Roof Hinge

    • Likely a sub-assembly of parts

  • Roof Hinge Mounting

    • Likely be a panel plus other mounting hardware

  • Roof Prop

    • Likely to be largely purchased

 

Integration

  • Mounting brackets to: chassis, trunk panel

  • Attaching hinge to hinge mount

  • Securing hinge mount to chassis

  • Ensuring roof prop can secure to the mounting brackets

Interdependencies

Trunk Prop

Based on the specific trunk hinge design. The trunk panel will have a specific motion. The trunk prop must be compatible with this specific motion, in order to remain in contact with it and to support the trunk panel when it is fully open

Link to trunk hinges:Trunk Hinges

 

As the trunk prop will remain in contact with the trunk panel throughout its range of motion, this also means it is in contact when it is in its closed position. Some trunk props / rods will continue to exert some sort of force even when the trunk panel is in a closed position. This loading must be communicated to the trunk latch DRIs to ensure it is accounted for in their calculations.

Link to trunk latch: See "Trunk Latch Project 2.0 (Current - S21)" for current project info

 

Roof Prop

As the roof panel will be fixed via a fastening method, it must be compatible with the unlocking / detaching of this fastening method in order to be able to tilt after.

Link to roof panel fastening: Roof Panel -- Aero-Chassis Integration