Automated Greenhouse Window Vent- Finalising the Design
Introduction
The past few lab sessions guided you through the different elements of designing a mechanism to control the opening and closing of a greenhouse window to regulate the temperature.
Several assumptions were made to simplify the process and allow you to practice some of what you have learnt in solid mechanics and see how it could be applied to a real-life problem. Another aim was to introduce you to the process of defining tolerances based on specific design requirements.
Summarising your proposed design
This lab session gives you the chance to bring everything back together and come up with a full mechanism design. An important part of the design process is being able to share your designs with others. Below is an example of how you may want to structure your mahara page. It includes a pdf that details different parts of the design. The powerpoint template used to create the pdf summary can be downloaded below, but you are free to structure it however you see fit.
Reflecting on the design
As mentioned earlier, in practice, a mechanism such as this one would likely be designed differently. For example:
- Friction and dynamic forces may be considered in the design, especially if higher loads were used.
- A bimetallic strip was chosen as it links to the content studies in solid mechanics, but other temperature sensors may be cheaper and easier to use.
- A geared DC motor was chosen, instead of a stepper motor, because it does not require digital input and can simply be controlled by the bimetallic strip. Stepper motors are the suitable choice if you require a holding torque. However, the load was considered low enough for the friction in the gears to be considered sufficient to keep the motor from turning.
- A rack and pinion mechanism was suggested, but there are many others that could be used.