Week 13

In today’s lesson, we learn about the operating principle and the mechanism behind the devices. Operating mechanism could be either mechanical, electrical, chemical or magnetism. For example, brewing coffee involves the leaching of coffee soluble.  

 

For our team’s chemical product which is air-to-water machine, the operating principle of the machine is to absorb water from the atmosphere with hydrogel via the absorption process. Afterwards, the water absorbed by the hydrogel is released via desorption process when exposed to high temperature. Hydrogel is a compound that contains thermo-responsive polymer in which water molecules desorb and condenses into liquid water in high temperature condition. 

 

Following, we learned more about the mechanism of devices which is something that transforms forces and movement into a desired set of output forces and movement. Mechanisms refers to the combination of rigid or resistant bodies, formed and connected so that they move with definite relative motions with respect to one another. 

 

There are 6 Essential Mechanism in Function Prototypes. They are actuators, cams, gears, lever, ratchets, and springs. 

 

Actuators 

Actuator converts stored energy into motion. The stored energy is usually in the form of compressed air, electrical potential, or liquid pressure. There are 3 principal types: electric, pneumatic, and hydraulic. 

 

Cams 

Cams convert a rotating shaft into simple or complex reciprocating linear motion. It can be sliding or rotating pieces in a mechanical linkage. For example, cams are usually found in cars because of the moving parts. 

 

Gears 

Gears are used to transmit torque and to adjust rotational velocity. There are many different types of gears such as spurs, helical, worm, planetary and bevel gears. The most common gears that are used in the industry are spurs, rack & pinion and bevel. 

 

Lever 

Lever is used to transmit and amplify force by fixing the input and output about a fulcrum or pivot point. 

 

Ratchets 

Ratchets lock in one direction, allowing them to tighten without fear of literally “going backward”. An example is cable ties. 

 

Spring 

A spring stores energy and dissipate energy. There are many types of spring such as compression, extension torsion, plate and constant force. 

 

Class Activity 

Moving on, we are tasked to design a Ping Pong Ball launcher that can shoot and reload ping pong balls. Thus, we came up with our design and sketch of gun that can launch the Ping Pong Ball. The launcher that we designed make use of mechanism such as spring and rachet to propel the ping pong ball. In this activity, there are 2 types of mechanisms which are propulsion mechanism and reloading mechanism. 

 

Propulsion Mechanism  

The ping pong launcher uses spring to store the energy which propels the ping pong ball. The piston is pulled back against the force of the spring and locked in place, storing potential energy. The chamber’s volume is now larger. A ratchet is used to hold the compressed spring in place. When the trigger is pulled, the piston is released and the spring forces it forward, causing the volume of the chamber to decrease and a rise in pressure. This rise in air pressure exerts a force to all the surface inside the chamber, including the back side of ping pong ball. Since the ping pong ball is relatively movable as compared to other parts, the force exerted on it causes it to move forward. Thereby, the ping pong ball is launched from the gun. 

 

 

Reloading Mechanism 

Reloading of the ball is accompanied by the spring that is compressed. When a ball is launched, the spring extends as there are more space now. In order to reload, the spring is pulled back using a handle on the side. It is to secure in place using the ratchet. Moreover, in the ping pong ball storage compartment, a spring is used to push the next ping pong ball to the firing compartment.