Gate 2 - Group 12 - 2012

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Preliminary Project Review

Work Plan

The disassembly plan functioned exactly as it was supposed to.

The following are highlights of it\'s successes:

  • Each individual part was documented as it was removed and photographed.
  • The tools needed were as expected, including allen keys, socket wrenches and screw drivers, with the addition of star keys.
  • Group members having experience working with combustion engines and landscaping equipment aided in the dissection immensely.

The following are highlights of its shortcomings:

  • Certain tools did not provide enough torque to loosen the screws, so makeshift tools were used (i.e. attaching a wrench to a screw driver).

Management Plan

The management did not go exactly according to plan, however, necessary changes were made as needed and functioned well.

The following are highlights of it\'s successes:

  • Our group meets in Capen Library every Tuesday and Thursday at 3:30, which turned out to be ideal because we all have the same class prior to that time.
  • We planned for more days in the lab than were actually necessary, which provided extra time for out-of-lab meetings.

The following are highlights of it\'s shortcomings:

  • Our planned time for lab dissection was originally Thursdays at 3:30, which turned out to not be a time at which the lab was open. This was corrected by agreeing upon Wednesday nights from 6 to 9 to be our designated lab time.
  • Communication was originally not going well, because all of our group members could not communicate with each other equally. Similarly we had no mechanism to share documents with the whole group. This was corrected by creating a private Facebook group in which we can all communicate in an open forum as well as share documents and pictures.
  • We had originally planned on meeting on the 3rd floor of Capen Library in private group rooms, which turned out to not be ideal because the group rooms were often all full. We got around this by changing our meeting location to the basement floor of Capen Library which is open for group study, and has plenty of table-space for our group to meet.

Product Dissection


Every part of this leaf blower was meant to be disassembled. Most components were held together by allen and star keys of the same size.

Components were also designed to be disassembled for ease of repair.

\'\'\'Difficulty Scale (Unscrewing):\'\'\'

\'\'\'(1)\'\'\' A loosely closed jar.

\'\'\'(2)\'\'\' A brand new unopened jar.

\'\'\'(3)\'\'\' A tightly sealed jar.

Step1.png \'\'\'Step one:\'\'\' Remove Turbine cover with a 4mm allen key (2)

Step2.png \'\'\'Step two:\'\'\' Remove the handle with a 4 mm allen key (2)

Step3.png \'\'\'Step Three:\'\'\' Remove the exhaust cover with a 3mm allen key (2)

Step4.png \'\'\'Step Four:\'\'\' Remove green front cover with 3mm allen key (2)

Step5.png \'\'\'Step Five:\'\'\' Remove fuel tank with 4 mm allen key, also pull fuel lines from carburetor (2)

Step6.png \'\'\'Step Six:\'\'\' Remove turbine blade with ½ inch ratchet (3)

Step7.png \'\'\'Step Seven:\'\'\' Remove turbine housing with 4mm allen key (2)

Step8.png \'\'\'Step Eight:\'\'\' Remove pull chord assembly with 4mm allen key (2)

Step9.png \'\'\'Step Nine:\'\'\' Remove crank shaft cover with star key (3)

Step10.png \'\'\'Step Ten:\'\'\' Remove air filter held in by clips (1)

Step11group12.png \'\'\'Step Eleven:\'\'\' Remove carburetor with 4mm allen key (2)

Step12.png \'\'\'Step Twelve:\'\'\' Remove exhaust/muffler with 4mm allen key (3)

Step13.png \'\'\'Step Thirteen:\'\'\' Remove piston with 4mm allen key (3)

Connection of Subsystems

Functional Model


Physical Subsystems:


\'\'\'All components together\'\'\'

  • Almost all subsystems are physically held together by either a Philips screw, hex bolt or Allen screw.
  • A minor percentage of the subsystems were held together by friction and/or clips.


\'\'\'This picture includes all subsystems almost completely disassembled.\'\'\'

  • For our group it was possible to dissect our product without the use of better tools in the machine shop. The subsystems were connected by tubes, channels, wires, and hoses.



\'\'\'This picture shows the carburetor while assembled attached the engine.\'\'\'

  • The operator turns the yellow knob to signal to the engine what speed they would like it to operate at.
  • The knob does so by controlling the amount of fuel allowed into the engine.
  • This also lets the user signal to the engine when to shut off. To shut the engine off the user turns the yellow know clockwise all of the way. This cuts off the fuel to the engine, thus shutting it off.


\'\'\'This is a picture of the carburetor off of the engine block.\'\'\'

  • The blue knob is used to allow the user to signal how much air should be allowed into the engine. This is also known as the choke. It helps the user start the engine while the engine block is cold.


\'\'\'The detached part in the picture above is known as the handle.\'\'\'

  • The operator holds this control the direction of the blower and signal which way they want the air output to go.


  • The black plastic pipe controls the direction of the air output.
  • The operator uses the handle to control which way the air output from the hose goes.



  • The mass in consists of fuel and air (for both the engine and in the turbine inlet).
  • The mass out consists of exhaust from the engine and air from the turbine.



\'\'\'This subsystem in known as the turbine.\'\'\'

  • The engine rotates the turbine to pull in air through the screen (that is currently disconnected in the picture) and force it out through the hose at speeds of up to 170 miles per hour.


  • Human energy is required to start this leaf blower.
  • The operator needs to pull this cord in order to start this engine.
  • Pulling on the chord turns the cranks shaft to create electrical energy (with the generator). The electrical energy creates the spark that ignites fuel in the combustion chamber.



  • The output of the engine crankshaft is torque. This is what spins the turbine, which results in the final output of an airstream.


\'\'\'This component is called a generator.\'\'\'

  • The generator uses the spinning crankshaft to extract electricity, which keeps the spark plug sparking.
  • Without this generator the engine could not run because it would not have a way to produce the spark that combusts the fuel.
  • Unlike automobile 4 stroke engines, this 2 stroke engine does not have a battery or an alternator to charge a battery.


  • The components shown in this subsystem include the crankshaft, piston and combustion chamber.
  • The carburetor controls the speed that these components run at by adjusting the air to fuel ratio and how much air and fuel enter the engine.
  • The fuel “explodes” in the combustion chamber due to a spark created by the spark plug.
  • The combustion then forces the piston down and sends the crankshaft into a rotation.
  • The energy that comes from the crankshaft is then converted into multiple types of energy such as torque and electrical energy.


  • The fuel tank is where the fuel gets stored.
  • It is entered through the hole that is covered by the screw on gas cap (in this picture it is being held).
  • From the fuel tank it is pulled into the carburetor through a hose and then from the carburetor it enters the combustion chamber.


  • Gaskets were used to prevent the loss of energy and keep subsystems and components leak proof. A leak could result in a huge energy loss.

Influential Subsystem Factors

Why Are They Connected?

The subsystems within the blower are connected for transfer of energy and signals. Almost all of the signals and physical components require human interaction which makes the product easier to maintain.

How Are They Implemented?

  • the lever for the choke is connected to the choke as a transfer between user input signal and the mass of air use for combustion in the engine.  :*the piston is connected to the rotary so that after the combustion process takes place it converts the energy from the combustibles to mechanical energy into the shaft and turbine.
  • The connections of air and gas are implemented in a liquid-tight seal, such as tubing, while most of the internal mechanics are through direct physical transfer.

All of the subsystems have been designed in a way that keeps a sufficient level of both functionality and usability while maintaining a level of simplicity that allows the consumer to be able to perform maintenance on the machine without requiring professional assistance.

GSEE Influences:

  • the product is most heavily influenced by societal and environmental concerns
Global Factors
  • materials used are common and easy to find, for example, plastic and metal
Societal Factors
  • society determined the need for this type of blower
  • designed for a middle-class consumer and home-owner
  • the handle provides a more ergonomic way to control the overall system
  • the muffler dampens the noise made by the engine, as to not bother or affect any third party users
Economic Factors
  • the gas tank holds a good amount of fuel, so it requires few refills, which means less money spent
  • because the parts are made from common materials, they are relatively cheap
  • the parts are easily replaceable
Environmental Factors
  • the yellow knob on the throttle controls the amount of gas that is drawn in to the system, using less gas means lower emissions
  • the blue knob controls the air intake of the turbine
  • the muffler catches some of the emissions due to combustion before it leaves the system, preventing it from escaping into the air

Arrangement of Subsystems

\'\'\'1. Gas Tank\'\'\'

  • Attached to the casing of the turbine
  • Off to the side, outside of the housing for the engine and other subsystems for easy access
Required Adjacent Subsystems:
  • Carburetor - Connected to the carburetor via fuel lines
Reason for Location:
  • Easy access for filling
  • Is separated from other systems to avoid any potential due to spillage of the fuel
  • Cannot be located near any subsystems that give off excess heat because the fuel is highly flammable

\'\'\'2. Carburetor\'\'\'

  • Mounted next to the engine
  • Sits on top of the gas tank
Required Adjacent Subsystems:
  • Gas Tank - Receives gas from the gas tank
  • Throttle - controls the amount of fuel going into the carburetor
  • Air Filter - Receives clean air from the air filter
Reason for Location:
  • Sits on top of the gas tank so it could be flush with the engine
  • Allows more accessibility to the yellow and blue knobs that control the gas and air flow, respectfully
  • Cannot be located near any subsystem with excess heat because it handles the fuel, which is highly flammable

\'\'\'3. Throttle\'\'\'

  • Housed in the yellow casing, on the side above the gas tank
Required Adjacent Subsystems:
  • Carburetor - controls fuel flow to carburetor
  • Engine - connected to the engine to communicate efficient fuel flow
Reason for Location:
  • Adjacent to all necessary subsystems
  • Must be placed in a closed/protected area

\'\'\'4. Generator\'\'\'

  • On top of the engine block
Required Adjacent Subsystems:
  • Crankshaft - extracts electricity form the crankshaft
  • Engine - Connected to the engine via the spark plug, where a spark is created by the electricity provided by the generator
Reason for Location:
  • Allows for the best connection to the engine
  • Needs to be kept away from heat sensitive subsystems, such as the gas tank, because it produces heat from the generation of electricity

\'\'\'5. Air Filter\'\'\'

  • Located beneath the carburetor
Required Adjacent Subsystems:
  • Carburetor - Provides clean air to the carburetor
Reason for Location:
  • Allows for clean air to be used in throughout the system
  • Needs access to clean air, so it cannot be located near the muffler

\'\'\'6. Muffler\'\'\'

  • The opposite side of the gas tank and carburetor, the other side of the engine
  • Over the exhaust
Required Adjacent Subsystems:
  • Engine - reduces the sound of the engine
  • Engine - exhaust is removed from the engine through the exhaust, then released through the muffler
Reason for Location:
  • Located away from the gas tank
  • Does not interfere with the user since the handle is in the middle of the system, right over the engine
  • Needs to be away from heat-sensitive subsystems because it releases heat

\'\'\'7. Pull Chord\'\'\'

  • Underneath the muffler
  • Outside of the turbine
Required Adjacent Subsystems:
  • Turbine - the chord turns the turbine blade
  • Crankshaft - chord turns the crankshaft to create electricity to start the engine
  • Engine - starts up the engine
Reason for Location:
  • Ergonomically located so it\'s easy to use by the operator
  • On the same rotational axis as the turbine blade so it could allow for easier pulling
  • Cannot be put in a difficult to access spot

\'\'\'8. Turbine\'\'\'

  • directly underneath the engine and all other subsystems
Required Adjacent Subsystems:
  • Pull Chord - turns the turbine blade
  • Crankshaft - turns when the turbine is started, and then kept going by the engine once the electricity is generated
  • Hose - pulls in air through the screen and forces it out through the hose at high speeds
Reason for Location:
  • Underneath the engine so the turbine can pull in air without any interference from other subsystems
  • On the same axis as the crankshaft and turbine for efficient rotational energy
  • Must have the screen exposed to the air because it needs to draw it in to the system to then force out through the hose
  • Must be in line with the crankshaft to start the entire system

\'\'\'9. Crankshaft\'\'\'

  • Located on top of the engine block
Required Adjacent Subsystems:
  • Generator - the crankshaft produces electricity which is provided to the generator
  • Turbine - the turbine is located underneath the crankshaft and is what starts the engine
  • Pull Chord - starts the system
  • Engine - the crankshaft is mounted on top of the engine, and is required in order for the engine to start
Reason for Location:
  • The crankshaft is set in line with the turbine for efficient rotational energy
  • Cannot be placed near a heat-sensitive subsystem, because the crankshaft gives off excess heat due to the electric current it\'s creating

\'\'\'10. Engine\'\'\'

  • Underneath the green front cover
  • Mounted on top of the turbine and its housing
Required Adjacent Subsystems:
  • Crankshaft - the engine is started from the electricity created by the crankshaft, which is mounted on top of the engine block
  • Generator - the fuel is ignited in the engine due to the spark created by the spark plug which is produced by the electricity from the generator
  • Muffler - the engine gives off post-combustion exhaust which is released through the muffler, the muffler also silences the engine
  • Carburetor - the carburetor injects the fuel into the combustion chamber which is located in the engine
  • Pull Chord - starts the entire combustion process in the engine
Reason for Location:
  • Centrally located in the system because of its importance
  • The central location allows the engine to be attached to all other necessary subsystems
  • Connected to the crankshaft and turbine for efficient rotational energy
  • Cannot be located around heat-sensitive subsystems, such as the gas tank, to avoid them from melting, or catching fire
  • the engine must be enclosed to avoid damage from outside elements