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Master Document

Automating the Bedroom Window

Concepts:

Using a linear actuator:

This is an attempt to use a linear actuator (self-contained unit) to solve the problem. While these can be expensive, the tradeoff will potentially be in time spent engineering, proving, and troubleshooting a custom solution. Therefore, this can also be thought of as an "easy-button" to solve the problem, which is not inherently an easy problem.

Considerations:

Drive type:

    • Ball-screws vs. lead screws
      • Ball screws  ~90% efficient - > can backdrive
      • lead screws ~ 40% efficient - > usually can't backdrive do to inefficiencies
      • Ball screws are more precise and expensive
      • lead screws sometimes use a plastic carriage rather than a steel
    • Belt drive seems more oriented towards horizontal applications, whereas ours is vertical
    • Ball screw is most likely the most appropriate for our application

Lubrication:

    • Screw drives and linear bearings usually require periodic lubrication
    • Lubricate using grease rather than oil for vertical applications
    • Some ball screws will advertise that they are maintenance and lubrication free (internally lubricated)
      • These products have a finite lifespan. Once the internal lubrication runs out, the product may fail.
      • Depending on our intended # of cycles and lifetime, such a product may still be appropriate.
    • Some lead screws advertise lubrication free
      • plastic on metal
      • Likely not suitable for our heavy-lift application

Linear guides:

    • will help align the window pane and resist the overhanging moment loads
    • therefore, these must be robust due to the high pitch and yaw moments (366 Nm)
    • a counterweighted system would be unable to counterbalance these moments, so we need robust guide rails to do so.

Travel life:

    • Travel life seems to be an important factor:
    • Assumptions for travel life. Raised/lowered once per day, everyday for 100 years
    • 650 mm of travel (1300 mm per open/close)
    • 48 KM traveled in 100 years worst case - on the very low side for these sorts of applications

Electronic Brake:

 

 

 

 

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