Gate 2 - Group 12 - 2012
(→Product Dissection) |
(→Arrangement of Subsystems) |
||
| Line 169: | Line 169: | ||
1. <u>Gas Tank</u> | 1. <u>Gas Tank</u> | ||
| + | |||
Location: | Location: | ||
*Attached to the casing of the turbine | *Attached to the casing of the turbine | ||
| Line 181: | Line 182: | ||
2. <u>Carburetor</u> | 2. <u>Carburetor</u> | ||
| + | |||
Location: | Location: | ||
*Mounted next to the engine | *Mounted next to the engine | ||
| Line 195: | Line 197: | ||
3. <u>Throttle</u> | 3. <u>Throttle</u> | ||
| + | |||
Location: | Location: | ||
*Housed in the yellow casing, on the side above the gas tank | *Housed in the yellow casing, on the side above the gas tank | ||
Revision as of 03:22, 26 October 2012
Contents |
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
Disassembly
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.
Step one: Remove Turbine cover with a 4mm allen key (2)
Step two: Remove the handle with a 4 mm allen key (2)
Step Three: Remove the exhaust cover with a 3mm allen key (2)
Step Four: Remove green front cover with 3mm allen key (2)
Step Five: Remove fuel tank with 4 mm allen key, also pull fuel lines from carburetor (2)
Step Six: Remove turbine blade with ½ inch ratchet (3)
Step Seven: Remove turbine housing with 4mm allen key (2)
Step Eight: Remove pull chord assembly with 4mm allen key (2)
Step Nine: Remove crank shaft cover with star key (3)
Step Ten: Remove air filter held in by clips (1)
Step Eleven: Remove carburetor with 4mm allen key (2)
Step Twelve: Remove exhaust/muffler with 4mm allen key (3)
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.
Signals:
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.
Mass:
- The engine accounts for most of the mass in the leaf blower. It is centralized under the handle to make a more comfortable feel for the operator and enables them control the leaf blower much easier.
- The engine is mostly made of metal.
- The rest of the leaf blower is mostly made of plastic. which is substantially lighter then metal.
Energy:
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.
Torque:
- 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.
Arrangement of Subsystems
1. Gas Tank
Location:
- 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
Purpose of Location:
- Easy access for filling
- Is separated from other systems to avoid any potential due to spillage of the fuel
Restrictions:
- Cannot be located near any subsystems that give off excess heat because the fuel is highly flammable
2. Carburetor
Location:
- 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
Purpose of 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
Restrictions:
- Cannot be located near any subsystem with excess heat because it handles the fuel, which is highly flammable
3. Throttle
Location:
- Housed in the yellow casing, on the side above the gas tank
Required Adjacent Subsystems:
- Carburetor - controls fuel flow to carburetor
