Subsystem Evaluations -(Group 10)
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In this section we take the major subsystems of our Snow Blower and analyze them explaining the connection of each subsystems using, Gate 2 table 1. Also we explain some of the GSEE factors and Give a Functional model of our engines system connections.
Linear Drive Assembly:
The snow blower is driven by a 9 hp horizontal combustion engine. The power from this engine is transferred to two separate systems, one being the front blades and the second being the drive train. The drive train consists of a vertical disk that is then moved over a horizontal disk that is then rotated from the friction between the two. The vertical disk receives its rotational power from the engine and the horizontal disk and connects to the chain system to turn the drive wheels. The way in which speed and torque is altered is by moving the vertical disk closer or father from the center of the horizontal disk. The closer to the center of the horizontal disk the higher the rpm’s but the lower the torque. This moving of the disk is made possible from the use of a clutch system that lifts the disk and allows it to slide to the left or right on a centrally connected shaft without causing any frictional movement between the vertical and horizontal disk. When the vertical disk is moved to the middle of the horizontal disk it encounters little to no rotational friction and therefore the system is now in neutral. Since the horizontal disk always turns in the same direction, if the vertical disk is moved to the opposite side and the allowed to touch the horizontal disk, the resulting rotation will put the system into reverse. This is because the vertical disk will rotate in the opposite direction then it would if it was in the forward drive area. These alterations of drive performance and function are performed by the use of external controls that include a lever for the clutch and a lever that moves the vertical disk from side to side. These controls are mounted near the handles of the snow blower.
Connections: There is a pulley belt that is connected to the horizontal shaft leading into the rear enclosure and linear drive. The shaft turns the horizontal disk. The horizontal disk turns the vertical disk(when they are touching) which rotates a small gear. The small gear then rotates a larger disk that’s corresponding shaft is connected to the chain and sprocket system. This chain turns its second sprocket which is connected to the drive axle and in turn turns the wheels. The Vertical disk is connected to a clutch system. The clutch is connected to a cable that is pulled to be engaged. The clutch system is connected to the vertical disk shaft and raises it off of the horizontal disk to allow the vertical disk to slide left or right, which is also controlled by the operator.
Physically: The clutch system is connected with pins to the vertical disk assembly and to the side of the drive enclosure with 2 bolts. The Chain and Sprocket assembly is connected to the vertical disk assembly by corresponding gears and is connected to the side of the drive enclosure with nuts and bolts. The idler pulley shaft is connected to the enclosure with pins and keyed shafts. The horizontal disk assembly is connected to both the bottom and internal wall of the enclosure with large steel nuts and bolts. The drive axle is connected to the enclosure by being run through both sides and having each end sealed in order to not be removed.
Signals: When the operator starts the engine it tells the horizontal shaft to turn chain drive. The chain drive tells the vertical disk to spin and turn the horizontal disk. The horizontal disk then tells the drive shaft to turn the drive axle which finally tells the wheels to turn. The operator tells the drive to move in reverse by pulling the clutch lever which tells the clutch to engage and lift the vertical disk. The operator then tells the vertical disk to slide over by pulling its control lever which engages its spring and moves it, allowing the disk to tell the horizontal disk to spin in the opposite direction by touching it on the opposite side.
Mass: There is rotational kinetic energy acting upon the system in both horizontal and vertical directions. This turns all of the components of the system.
Energy: Energy from the engine is transferred to a horizontal shaft. Energy from the shaft is transferred to a shaft connected to the chain drive in the rear enclosure. The sprocket being rotated by the chain is connected to a shaft that transfers rotational energy to the vertical disk. The vertical disk when toughing the horizontal disk transfers frictional-rotational energy which turns the horizontal disk. The horizontal disk turns a shaft that is connected to the drive axel and in turn, turns the drive wheels, thus moving the snow blower.
The auger is the part of the snow blower that actually picks up the snow and throws it. It is located is located in the front of the snow blower. The auger is composed of an auger fan, auger fan shaft, auger shaft and two auger blades. The auger fan shaft is connected to the pulley-belt system which provides the rotational energy needed to pick up snow. The auger shaft has a gear and worm gear in the center which transfers the rotational energy from the auger fan shaft to the blades which are attached to the auger shaft. The auger shaft is also connected to the front housing of the snow blower which is responsible for directing the snow into the snow blower and serves a safety barrier between the blades of the auger. The two auger blades are spiral/curved metal blades that are attached to hollow tubes that slide on to each end of the auger shaft. Washers and bolts are used to keep the blades attached to the auger shaft with minimum side to side movement and the auger shaft securely connected to the front housing. The auger fan is responsible for sending the collected snow up and out of the chute.
Connections: Connections in the auger system consist of the connection between the pulley belt system to the auger fan shaft, the auger fan shaft to the auger shaft, auger blades to the auger shaft and auger shaft to auger housing.
Physically: The pulley belt system is connected to the auger fan shaft with the auger drive belt. The auger fan shaft is connected to the auger shaft through a gear box consisting of a gear and worm gear. The auger blades are connected to the auger shaft and held in place with a large bolt on each side of the shaft. The auger shaft is connected to the auger housing (front housing) with a steel plate and there bolts on each side.
Energy: Rotational mechanical energy is transferred from the pulley belt system to the auger fan shaft to the auger blade shaft and finally to the blades.
Reason For Connection: The pulley belt system is connected to the auger fan shaft in order to provide it with the rotational energy needed to rotate the shaft. The rotation of this shaft is used to rotate the auger shaft which is why these two shafts are connected. The auger blades are connected to the auger shaft so the blades themselves receive the rotation needed to pick up snow. The shaft is connected to the front housing in order to keep the auger system secure and in place with the snow blower as a whole.
Signals: The user is presented with the ability to control the auger via a rod with a handle that extends to the control panel. The two options are “on” and “off”.
The chute of the snow blower is used to control and direct the displacement of snow. It enables the user to easily change the direction that the snow is being blown in with the simple rotation of a handle. The chute is composed of a simple piece of curved metal that is welded on to a gear base and is turned by a worm gear that is attached to a handle that receives manual mechanical energy from the user.
Connections The connections that go into the cute system include the chute rotation handle to the chute, and the chute to the frame.
Physically The chute rotation handle is connected to the chute with a steel pin and washer. At the end of the handle is a worm gear that turns the gear base that the actual chute is welded on to. The chute itself is attached to the frame of the snow blower with 6 nuts, bolts and washers each.
Reasons For Connection The reason for the connection of the rotation handle to the chute is to provide the user with the ability to rotate the chute and throw the snow in a desired direction. The chute itself is attached to the frame so it remains as one part of the snow blower.
Energy Rotational Energy provided by the turning of the rod by the user is transferred to the chute in order for it to turn to desired direction.
Signals The chute rotation handle is a signal for the user to use that handle to control where the snow will be displaced once it comes out of the chute.
Connection 1- Pull Start
-Physical Connection: Connected to the side of the engine by 4- 12mm bolts equally spaced apart equally. The pull start contains a handle on the outside and a string on the inside with a spring that allows it to retract after it’s pulled.
-Energy Involved: The Pull Start receives energy from the user, when the user pulls on the pull start. The pull start then rotates creating rotational energy which is used to spin the crankshaft.
-Why it's Connected: The pull start exists because it allows energy to enter the engine which needs an energy source to work and run.
Connection 2- Fly Wheel
-Physical Connection: Connected on the crankshaft by a press fit with a key-stock. The flywheel moves in a circular motion causing the crankshaft to move.
-Energy Involved: The flywheel gets rotational energy from the user pulling the pulley and converts it to mechanical energy to spin the crankshaft. -Why it's Connected: The flywheel is connected because the mass of the flywheel uses inertia to keep the crankshaft turning, and also keeps the rotation constant allowing the engine to run smoothly.
Connection 3- Crankshaft
-Physical Connection: Held on tightly by the main engine and the main engine block when together. The crankshaft sits inside the engine, with its rods sticking out on the outside.
-Energy Involved: The crankshaft uses the mechanical energy gained from the flywheel to spin and push the piston up and down the piston chamber.
-Why it's Connected: The crankshaft is connected because it’s shape allows for the piston which is attached to it, to move up and down, and with a gear being able to be placed on the crankshaft also allows to camshaft to operate and allow to the valves to operate properly. The crankshaft serves as the main part for everything to go together and function properly.
Connection 4- Camshaft
-Physical Connection: The camshaft is also fit on the inside of the engine. A piece of metal which is screwed on by two bolts holds the camshaft in place which sits in a hole. The gear on the camshaft is also connected to the gear on the crankshaft.
-Energy Involved: Since the camshaft is connected to the crankshaft by a gear it shares the mechanical energy that that crankshaft gains. It uses this energy to open and close the valves at precise times to allow for combustion to occur.
-Why it's Connected: The camshaft is connected to the crankshaft because the crankshaft controls the piston which is used for combustion. In order for combustion to occur, air and gas is needed which comes in through the valves and the camshaft serves as the tool for opening and closing the valves. The size gear on the camshaft is made just right so the RPM is just right to allow for the valves to open and close at appropriate times to let in air and gas, allow combustion to occur, and then let the exhaust out. This cycle is repeated without failure if the appropriate gear size on the camshaft is used.
Connection 5- Piston
-Physical Connection: The piston is connected to an arm which on one end is connected to the piston by a pin and on the other end is a half circle opening. The other half circle piece wraps around the crankshaft and is fastened to the piston arm using two bolts.
-Energy Involved: The piston is attached to the crankshaft so it shares the mechanical energy which the crankshaft gains and uses it to move up and down the piston chamber which allows for combustion to occur.
-Why it's Connected: This piston is connected the crankshaft because it allows for perfect motion of the piston. With the crankshaft turning constantly, is allows the piston to continually produce energy though combustion. The piston arm is also an accurate measured piece which allows the piston to go just high enough so that spark plug can send the spark and allow for combustion to occur.
Connection 6- Carburetor
-Physical Connection: The carburetor is connected to the engine on the outside where the intake valve chamber is and the fuel line is connected to the carburetor. The carburetor is connected two Philips head screws to the intake chamber which lets in fuel and air into the combustion chamber. The choke is attached to the carburetor which helps the engine start when it’s cold.
-Mass: The gas and air travel through the carburetor into the piston chamber.
-Why it's Connected: The carburetor is attached to the intake chamber because it allows it to produce the correct fuel and air mixture that travels to the combustion chamber and allows for combustion to occur. The fuel line is connected to the carburetor and the carburetor controls the amount of fuel that it needs to release for each cycle of combustion. The choke which is attached to the carburetor which if used allows more fuel to travel to the combustion chamber. This is needed because at colder temperatures the fuel vaporizes easily which makes combustion harder to occur, so the choke simply allows for more fuel to travel to the combustion chamber to allow for steady reaction of combustion.
Connection 7- Muffler
-Physical Connection: The Muffler is connected to the engine on the outside where the outtake chamber is. The Muffler is attached to the engine by two Philips head screws which hold the Muffler in place.
-Energy Involved: The Muffler releases heat energy that was produced by combustion.
-Mass: The exhaust travels from the combustion chamber to and out the muffler.
-Why it's Connected: The Muffler is connected to the engine because it allows for the exhaust to travel out of the system. Without a muffler the engine could also be louder so the muffler also reduces the sound level the engine produces.
Connection 8- Spark Plug
-Physical Connection: The Spark plug is connected to the engine by it having threads and being able to be screwed into the header. A 21mm socket wrench is used to connect and disconnect the Spark plug.
-Energy Involved: The spark plug releases electric energy that provides a spark for the combustion chamber.
-Signals: Once the piston reaches the top of the chamber, which is the point where the fuel and air mixture is compressed, the spark plug sends the spark, igniting the mixture and causing combustion.
-Why it's Connected: The Spark plug is connected because it gives the fuel and air mixture that goes into the combustion chamber the spark it needs to combust.
Connection 9- Combustion Chamber
-Physical Connection: The combustion chamber which is located under the header is connected by several bolts which hold the combustion chamber in place.
-Energy Involved: The combustion chamber forms chemical energy, by using the fuel and air mixture it receives and then allowing the piston, which is using mechanical energy to compress the fuel and air mixture which receives a spark to combustion. Then the energy is released through the exhaust.
-Mass Involved: The combustion chamber when in use contains fuel and air and after combustion contains the exhaust which later releases and then follows the cycle of obtaining and releasing these three materials.
-Why it’s connected: The combustion chamber needs to be on the engine in order for an energy source to exist. The combustion chamber’s small size allows for the fuel and air to be compressed so that combustion can easily occur and therefore produce energy for the engine.
GSEE Concerns Influencing the Design
The global concerns that come into conflict with the snow blower is that certain bolts are in standard measurement while other are in metric measurement which would require both sets of tools. This may be due to the manufacturer using a collaboration of different companies to put the snow blower together. Another concern is the amount of snow the snow blower is intended to be used in. Since this snow blower has linear drive, it allows for moving through large amounts of snow which would be difficult otherwise for the user to push the snow blower through the snow.
Some societal factor that were considered when manufacturing the snow blower were weather of not the user will be able to push the snow blower. For this reason a drive system was implemented to help the user be able to remove snow without using much force. Another societal factor implemented was the chute turner which allows the user to throw snow in his or her desired direction instead of a single directed direction. This allows for the user to be able to place snow where it can be convenient and cause no trouble. The snow blower also comes with an idle option which allows the user to be able to idle the engine if he wishes to take a break during the time he is removing snow, and not have to worry about pull starting the engine again.
The economic factors that went into designing the snow blower were focused to saving the consumer time and money. One factor was to make the snow blower out of steel, which makes it durable. With a steel snow blower the user doesn't have to worry about it breaking because of ice scraping against it or ice falling on it. A plastic snow blower will be more susceptible to ice breaking it, and therefore the manufacturer made this particular snow blower out of steel to allow the user to be able to use it for a long time.
The environmental factors that went into making the snow blower were deciding what to make the snow blower out of. By using steel and cast iron and aluminum components, these components can be recycled after the snow blower stops functioning. A single cylinder engine was also used so that less exhaust is released into the environment, so that environmental friendly users may also use the snow blower and not be worried about the harm they on putting on the environment.
Influence for Performance
The manufacturers took performance requirements into account when designing the methods in which the engine of the snow blower is started. They implemented an electric start along with a manual start for the engine. This is so that if one method of starting fails, there is a backup method.