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Single Sliding Bar Mechanism

  • As seen in the image above, there is (at a minimum), 5mm of clearance between the top of the chassis tube and the bottom of the roof panel

    • This does not provide sufficient space for the single bar sliding mechanism

      • Unless an unconventional, super low-profile design is utilized

        • This may present manufacturing issues however

  • Instead of having a mechanism that is placed within the car even when the roof is closed, an “add-on” roof prop mechanism was chosen

Logic for above decision is as follows:

  • Roof would/should never open while car is travelling, thus there does not need to be a roof prop mechanism that is integrated within the roof/chassis

    • Where (as seen above) there was not enough space

  • An “add-on” roof prop mechanism can achieve the same goal (propping up the roof when the car is stationary) while avoiding the limited space issue

    • However, some components of this mechanism/system will have to remain integrated within the car

      • (potential) roof hinges

      • Roof to prop connector/connection

    • Roof prop itself will be removable

The rest of this section will now cover the concepting and researching behind the following components of this “add-on” roof prop mechanism:

  • Roof prop

  • Roof hinge

  • Roof to prop connection

Selected Concepts

Trunk

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  • Selected concept based on further research and feasibility analysis: Compressed air struts

Main reasons:

  1. Ease of use

  2. Ease of implementation

  3. Manufacturing time

Ease of Use (1)

Based on the research done in the previous section, it was evident that the user interaction would be much easier and streamlined with the compressed air struts compared to the 2 bar linkage system.

Compressed Air Strut:

  • Opening the trunk: User unlocks trunk latch and lifts trunk. Compressed air struts prop trunk and keep it open (no user interaction needed beyond lifting of trunk)

  • Closing of trunk: User pulls down to close trunk panel, locks trunk latch

2 Bar Linkage System:

  • Opening the trunk: User unlocks trunk latch and must lift trunk for entirety of its range of motion. User then needs to slightly lower the trunk to engage the “Bird’s Mouth” Lock

  • Closing the trunk: User needs to raise the trunk panel slightly to disengage the “Bird’s Mouth” Lock. User then pulls down to close trunk panel, locks trunk latch

2 Bar linkage system’s process is: lengthy, not intuitive and cumbersome

Ease of Implementation (2)

As can be seen in the previous section, there were notable concerns with the 2 bar linkage system.

2 Bar Linkage system - Locking (to keep Trunk open):

  • Basic assembly did not account for gravity. Therefore hard to verify if the “Bird’s Mouth” Lock could easilybe engaged.

    • There were some cases where the top bar may not translate diagonally and could instead rotate. This would not properly engage the “Bird’s Mouth” lock

    • In the end more testing would be required

2 Bar Linkage system - Unlocking (to close Trunk):

  • Basic assembly did not account for gravity. Hard to verify if gravity would pull bottom bar down and for the entire assembly to fold into itself (like how it was shown in the video)

    • Again more testing would be required if this would happen in real life

2 Bar Linkage system - Summary:

  • Need to conduct more testing, making design process longer

    • Could use SolidWorks motion study to account for gravity

      • But the slot mate used to connect top and bottom bars was not compatible with motion study

    • Could build scaled down model

Compressed Air strut - Summary:

  • Used hand calculations to verify struts could keep the trunk open

    • To be safe, each one of the struts can keep the trunk open

      • Therefore even if one fails, the other will be enough to ensure trunk stays open

  • Used hand calculations to verify user could easily close trunk

    • In accordance with OSHA guidelines for allowable pulling forces one can exert

  • Overall more confident that it can work as intended as opposed to 2 Bar Linkage system which still had major uncertainties

Manufacturing Time (3)

2 Bar Linkage system:

  • Simple geometry but would still require manufacturing and assembly time

  • Would also take up manufacturing resources

    • Regardless of if we do it in-house or outsource it, it is a manufacturing resource that is being used

Compressed Air strut:

  • Would not need to be manufactured

    • Only the mounts need to be manufactured

      • But those need to be manufactured for 2 Bar Linkage system as well

  • Frees up manufacturing resources

  • Was reasonably priced (approximately $63.00 CAD for a set of two from McMaster-Carr)

    • Therefore price was not an issue

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