Week 13: Operating Principles & Mechanism Designs

In week 13's lesson, we were being introduced to the relationship between products' operating principles and their mechanisms. Mechanisms are essentially required for identified operating principles to work efficiently. These mechanisms include but not limited to actuators, cams, gears, lever, ratchets and springs. An example given to show the relationship was the control valve. The operating principle of a control valve is such that the valve stem needs to move away from the valve seat to allow passage of medium. To do so, an actuator will be needed to convert the stored energy such as compressed air, electrical potential or liquid pressure to rotation motion where the valve stem will then be lifted to open the valve. Another example would be springs, where they will store energy when being compressed or stretched, and dissipate the energy when being released.

To apply the knowledge that we had just learned, we were assigned to design a ping pong launcher and be able to explain its principles and mechanisms as a group. We started off with brainstorming the kinds of ping pong launchers on the market and finalised that it will be one that is easy to reload the ping pong balls and simple to use. The ping pong ball launcher we designed will make use of propulsion principle which allows the players to use rubber band as the energy storage mechanism to propel the ping pong ball. The scenario would be: The user manually pull the rubber band and let go to fire the ping pong ball. After a ball is fired, pull the plunger to the back for another ball to fall into the chamber ready for the next shoot. Once all balls are fired, the user then reload the ping pong balls via gravity to a tube where balls are held. Figure 1 shows a sketch of the designed ping pong ball launcher.

Figure 1: Sketch of Ping Pong Launcher

After the activity, we were tasked to relate the concepts with the chemical products that we were doing, i.e. phone disinfection device via chemical vapour. The two major principles that the disinfection device will be relying on would be pressure and diffusion. Pressure is required to force the disinfectant i.e. chemical vapour into the tubes connected to the nozzle. Pressure is also used by the nozzle itself to convert the high pressure of cartridge with chemicals to high amounts of velocity and hence turning the chemicals into chemical vapour mists to disinfect the phone. As for diffusion, it is applied when the disinfectant converts to mist comes out from the nozzle, diffuses and lands onto the phone and proceeds to disinfect the phone surface. To enhance the effects of these principles, a motor i.e. piston pump is used to turn a cam system which is what drives the discharging of chemical disinfectant to disinfect phones placed inside. Figure 2 shows the sketch of the designed phone disinfection device.

Figure 2: Sketch of Phone Disinfection Device

In general, it was a fun lesson as we got to think of practical ways to make everything in life functional and usable.

Blogged by:

Zhi Ying