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Roof Prop

Two types of roof props will exist: fixed length or variable length

Fixed length:

• Standard rod

  • Essentially a metal or composite rod of a fixed length

Variable Length:

• “Snap Lock”

  • Telescoping rod with a snap on lock, very similar mechanism to those found on telescoping tripod legs

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    • Once the lock is “snapped on”, it induces a compressive force onto the outer tube

      • Which then induces a compressive force onto the inner tube

      • This causes the two tubes to be in contact with one another and therefore frictional force prevents movement of the inner tube

    • Quite user friendly

      • Does not require a lot of input

    • Making the locking mechanism may be quite complicated

      • Need to research applicable manufacturing processes' as well as materials

      • Note: locking mechanisms can be purchased separately and this may allow us to circumnavigate the potential manufacturing issues of this

• Spring Loaded Pin

  • Pin that is attached to an internal spring

    • In the spring’s unstretched position the pin protrudes out

    • User depresses pin and then moves inner rod to desired length

      • Spring will naturally extend back to its unstretched position and pin will protrude out into holes drilled into outer rod, thus locking it in place

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    • Assembly may be quite intricate

      • Making sure the spring and pin are properly assembled within inner rod

    • Restricted to set positions

      • Based on holes drilled into outer rod

    • Not user friendly

      • Sometimes is hard to depress the pin enough while moving the inner rod

• Internal CAM Lock

  • A cam is attached to the inner rod, it is shaped such that when the inner rod is twisted a certain number of degrees, it will push out on a set of plastic/metal halves

  • These plastic/metal halves contact the outer rod

    • Frictional force prevents movement of the outer and inner rods

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  • Assembly of this may be quite complicated

    • Ensuring plastic/metal halves are positioned properly

    • Needing to ensure cam is mounted/positioned properly

    • May be more efficient to purchase this item

  • Quite user friendly

    • Locking/unlocking motion is done by twisting one of the rods

  • NOTE: This may be require additional features to be compatible with some of the mounting methods discussed below

Prop Mounting

The roof prop will need to be mounted to both the roof and chassis of the car in order to properly support the roof

It is also important to note that as the roof prop may need to be removed, the mounting hardware should allow for this as well

Roof Mount:

• Eye bolt

  • The prop itself will have an “eye bolt” on its end while the roof will have an mounting brackets with threaded holes for the bolt to run through

    • The “eye bolt” will be placed such that the bolt runs through it as well (see picture below)

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    • NOTE: To be compatible with the twisting motion of the internal cam lock system, the prop would have to be able to ROTATE INDEPENDENTLY of the fish eye hook

      • For the other prop mechanisms discussed above, this mounting method works directly as is

    • This system is generally quite simple and straightforward

      • Which should make manufacturing and design easier/faster

• J Bolt

  • The prop will have a “J Bolt” while a shoulder bolt that runs through two brackets will be mounted to the roof

    • The “J bolt” will then latch onto the shoulder bolt (see below)

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    • NOTE: To be compatible with the twisting motion of the internal cam lock system, the prop would have to be able to ROTATE INDEPENDENTLY of the fish eye hook

      • For the other prop mechanisms discussed above, this mounting method works directly as is

    • System is easier to use than the “Eye bolt” as the prop only needs to be lifted up to unlock, as opposed to sliding out

    • The flanges on the mounting brackets must be sufficiently long enough to allow for enough clearance space to engage and disengage the “J Bolt” from the shoulder bolt

      • These flanges are essentially cantilevered beams so the longer they are the greater potential they have to deflect / deform

Chassis Mount:

• Hook to Chassis Tube

  • A hook on the end of the prop would rest directly on the chassis bar in the previously mentioned blue highlighted area

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  • No additional mounting hardware needed, so this theoretically simplifies manufacturing process

  • However, will need to manufacture a hook/integrate a purchased solution such that it will be in this orientation

• Hook and Pin

  • General concept remains the same as how it is applied in the roof mounting scenario

  • Due to the geometry in the mounting area, a pin would potentially be press-fit into a block which would then be adhered onto the bulkhead panel (see below)

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  • This concept requires more mounting hardware

    • Overall more manufacturing work and also adds a bit more weight to the car

  • In addition the concern with how to press-fit the pin/dowel remains

  • May be easier to integrate the end piece (hook) onto a rod than the “Hook to Chassis Tube” method

• Hook and Pin (C-Bracket Variant)

  • Same general concept as above, but instead of a dowel press-fitted within a block, it is placed within a C-bracket

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  • If an adhesive is being used to connect the C-bracket to the bulkhead, then the contact area between the two must be sufficient to allow the bracket to stay in place

    • Would need to calculate this area based on the adhesive and specific material of the C-bracket

• Hook and Pin (Platform Variant)

  • If the required contact area between the bracket and bulkhead is too large, an oversize C-bracket would have to be used, which may take up an unnecessary amount of space

  • In this case an L-bracket (or just an L-shaped piece of sheet metal) is used to obtain whatever necessary contact area is needed

    • On the flange of this L-bracket is a smaller L-bracket with a dowel/shoulder bolt through it that runs through it and to a hole into the larger L-bracket (see image below)

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    • Compared to other methods this is more cumbersome and utilizes more parts

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

• Roof Prop

  • One acts as a hinge replacement

  • Other retains the same functionality as before (changes length to alter angle of roof)

• Prop Mounting (to Roof and Chassis)

See video below for clarification

• Top rectangle represents the roof

• “Hinge replacement” prop is the one on the right

Note: For clarity the the areas highlighted in red are where the roof props could potentially be mounted on the B Panel Bulkhead

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Pros of this architecture:

• No hinge design is required, this simplifies both the operation and manufacturing

• This would be an entirely closed system, and would not require the prop to be removable

• Roof could be opened while remaining within the vehicle

Cons of this architecture:

• The “hinge replacement” prop must be restricted from rotating

• May be issues with ensuring the roof’s motion is purely vertical in the beginning stages

• Will need to create an enclosure for the props so that the occupants will not come into contact with them in the event of an impact

• The mounts to the chassis will need to have flanges long enough such that the prop will not interfere with the motion of the roof

  • The longer these flanges are, the greater the potential for them to yield/fail (essentially a cantilever beam)

Expand
The Google Doc linked below contains all the following content for this section. This was done as doing it within Confluence’s built-in word processing was getting messy and unorganized. Google drive docs width 720 showLink true url https://docs.google.com/document/d/1CCwGOWY7R8nmJOKmoRsVYOPtctsRLJMWH11a8YYiBiw/edit?usp=sharing height 960 Single Sliding Bar Mechanism Image Removed 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 There are different system architectures to achieve this and these will be discussed below The following will now cover the concepting and researching behind the specified architecture of this “add-on” roof prop mechanism: Roof Prop Roof Hinge Prop Mounting (to Roof and Chassis) Note: For clarity the the areas highlighted in red and yellow are the potential Roof Hinge mounting areas, while the areas highlighted in blue and green are the potential areas where the Prop Mount (to the chassis) could be located Image Removed Because the B-Panel bulkhead does not extend to the top of the chassis, some ideas for the Roof Hinge will require an additional panel (made of an appropriate material) to be attached to the chassis tubes for the highlighted area in Red For the same reason as above (B-Panel bulkhead not extending to the top) some ideas for the Prop to Chassis mount will require an additional panel to be attached to the chassis tubes for the highlighted area in Green This will be denoted in the title of the idea
Roof Hinge It is important to note that the top of the roof panel will be flush with the tops/edges of the side panels Thus, any hinge design considered must be able to lift the roof panel to be cleared/above the side panels. (i.e. the roof panel does not collide/interfere with the side panels during opening and closing) Four Bar Multi-point Hinge Similar to https://www.youtube.com/watch?v=O8gBLLizI3s Or https://www.youtube.com/watch?v=6bMMZq0X29E Assembly process may be more intricate and time consuming Quite a few moving parts, but this is a proven system that has many applications Mounting may be an issue as there does not seem to be space for this in the interior cabin area Pop up Hinge (requires additional panel) Similar to https://www.youtube.com/watch?v=kh252HOZrqc Seems like this will take up more mounting room Concern with the top peg being constantly forced against the top of the slot Would need to ensure the mounting plate (that has the slot) is adhered on properly to provide a sufficient reaction force to the peg’s upward force Motion is also not necessarily smooth and continuous, could be a cause for concern Will have to mount this system flush against the bulkhead Four Bar Hinge (requires additional panel) This design seems to be utilized in other solar cars as well Four Bar Linkage Roof Hinge.wmv Simpler than the multi-point hinge variant Mounting space is larger than multi-point hinge but less than pop up In MSXIV would have to mount this against the bulkhead panels in order to be feasible Block with two threaded holes could be adhered to the bulkhead panel Shoulder bolts threaded into those holes would then support the moving linkages seen in video above

Selected Concepts

Trunk

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