Gate 3 - Group 12 - 2012

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Contents

Introduction

In the previous gate the group dissected the Weed Eater Variable Speed Handheld Blower and documented the process. The group performed an analysis of each part and subsystem. From this the group discovered how each subsystem and component interacted together. Each subsystem has a specific job to do in order to contribute to the overall function of the product. Gate 3 will allow the group to take a further more detail oriented look at specific subsystems. The GSEE (global, societal, economic, an environmental) factors that impact the design of the Weed Eater Variable Speed Handheld Blower will be examined. This analysis will also provide design revisions to the original product to improve it.

Coordination Review

Cause for Corrective Action

This gate compared to gate 2 required less hands-on work and more analysis work. Gate 2 helped the group to more fully understand how the product works, this has made the work needed to be done for this gate a lot easier. However, our main issue for the last gate was time management.

Prior to gate 2, the group would send all of the work to one group member. That member would then upload and format everything on the wiki page by himself. Midway through the second gate, we realized that uploading to the wiki page was very time consuming and just too much work for only one person to complete. So the decision was made to have another person learn the wiki language and have them simultaneously put up the group work for the gates. The work was more easily divided, which aided in completing this assignment.

Now since the group is in a steady groove of meetings, everything seems to be coming together which has, in turn, made these assignments less stressful. This gate, however, coincided with a high number of exams for each group member. With that as an obstacle, some group members had an issue for getting their work completed at an acceptable time. Though the group is meeting and discussing what needs to get done each week, some still have a problem of actually completing and handing in quality work for his section. To fix this we, as a group, will need to push harder for deadlines to be met, and for it to be made clear that we are all affected by each members individual performance.

After this gate is completed the group goes home for Thanksgiving break, which means that there won\'t be a meeting next week. To stay on track for gate 4, the group has created Facebook group page where we are able to post pictures, documents, keep in contact with each other, and continue our work without missing a beat.

Product Evaluation

Component Summary

The following is a list of the product\'s components.

Each component is described with its material, how it was manufactured, the number of times it is used, and some other important information.


\'\'\'Turbine Cover\'\'\' (Fig. 3-1)

\'\'\'Fig. 3-1\'\'\' Turbine Cover

Material:

  • Plastic

Manufacturing Process:

  • Injection Molding

Number of Times Used:

  • Once

Other Information:

  • Made to house the turbine.


\'\'\'Handle\'\'\' (Fig. 3-2)

\'\'\'Fig. 3-2\'\'\' Handle

Material:

  • Plastic

Manufacturing Process:

  • Injection Molding

Number of Times Used:

  • Once

Other Information:

  • Assists users in holding the device


\'\'\'Exhaust Cover\'\'\' (Fig. 3-3)

\'\'\'Fig. 3-3\'\'\' Exhaust Cover

Material:

  • Plastic

Manufacturing Process:

  • Injection Molding

Number of Times Used:

  • Once

Other Information:

  • Made to house the exhaust and engine


\'\'\'Green Front Cover\'\'\' (Fig. 3-4)

\'\'\'Fig. 3-4\'\'\' Green Front Cover

Material:

  • Plastic

Manufacturing Process:

  • Injection Molding

Number of Times Used:

  • Once

Other Information:

  • Houses the engine, exhaust, and all other inner components


\'\'\'Fuel Tank\'\'\' (Fig. 3-5)

\'\'\'Fig. 3-5\'\'\' Fuel Tank

Material:

  • Plastic

Manufacturing Process:

  • Injection Molding

Number of Times Used:

  • Twice
  • to store the fuel
  • pump the fuel into the engine

Other Information:

  • Made to hold and transport the fuel


\'\'\'Turbine Blade\'\'\' (Fig. 3-6)

\'\'\'Fig. 3-6\'\'\' Turbine Blade

Material:

  • Plastic

Manufacturing Process:

  • Injection Molding

Number of Times Used:

  • Once

Other Information:

  • Converts energy into useful work


\'\'\'Turbine Housing\'\'\' (Fig. 3-7)

\'\'\'Fig. 3-7\'\'\' Turbine Housing

Material:

  • Plastic

Manufacturing Process:

  • Injection Molding

Number of Times Used:

  • Once

Other Information:

  • Holds the turbine in place


\'\'\'Pull Cord\'\'\' (Fig. 3-8)

\'\'\'Fig. 3-8\'\'\' Pull Cord

Material:

  • Plastic
  • Rope

Manufacturing Process:

  • Injection Molding

Number of Times Used:

  • Once

Other Information:

  • Used to manually start the engine


\'\'\'Crankshaft Cover\'\'\' (Fig. 3-9)

\'\'\'Fig. 3-9\'\'\' Crankshaft Cover

Material:

  • Plastic

Manufacturing Process:

  • Injection Molding

Number of Times Used:

  • Once

Other Information:

  • Contains the crankshaft
  • Prevents foreign objects from entering


\'\'\'Air Filter\'\'\' (Fig. 3-10)

\'\'\'Fig. 3-10\'\'\' Air Filter

Material:

  • Foam

Manufacturing Process:

  • Cut from a larger piece of foam

Number of Times Used:

  • Once

Other Information:

  • Made to improve the quality of air entering the engine


\'\'\'Carburetor\'\'\' (Fig. 3-11)

\'\'\'Fig. 3-11\'\'\' Carburetor

Material:

  • Plastic

Manufacturing Process:

  • Injection Molding

Number of Times Used:

  • Once

Other Information:

  • Controls the air inlet


\'\'\'Exhaust/Muffler\'\'\' (Fig. 3-12)

\'\'\'Fig. 3-12\'\'\' Exhaust/Muffler

Material:

  • Steel

Manufacturing Process:

  • Extrusion
  • Sawing
  • Rolling

Number of Times Used:

  • Three times
  • Filter air
  • Remove air
  • Reduce noise

Other Information:

  • Removes unwanted air from the engine, filtering it, and reducing the noise output


\'\'\'Cylinder\'\'\' (Fig. 3-13)

\'\'\'Fig. 3-13\'\'\' Cylinder

Material:

  • Steel

Manufacturing Process:

  • Extrusion
  • Sawing

Number of Times Used:

  • Once

Other Information:

  • Made to contain the crankshaft, and keep it in place

Product Analysis

The following components\' complexities are based on a scale from 1-3:

\'\'\'1\'\'\' - three or less governing equations
\'\'\'2\'\'\' - three to six governing equations
\'\'\'3\'\'\' - six or more governing equations

The scale was determined based on the number of governing equations the specific component has.

Piston

Piston1-12.jpg Piston2-12.jpg


\'\'\'Component Function:\'\'\'

The piston was chosen for its relevance to the overall function of the leaf blower. That is, the leaf blower’s purpose is to blow leaves for landscaping necessities. This function is achieved through the energy produced in a 2-stroke combustion cycle. The piston is the component that directly receives the boundary work of this cycle and converts it into translational motion. This translational motion is then converted into rotational motion by the crankshaft in the bottom end of the piston, which is then used to spin the turbine and thus create airflow. The component functions in a sealed internal chamber known as the combustion chamber, which is located inside the cylinder of the engine. In general, the flows associated with this part are as follows: Air, fuel and heat (in the form of the spark ignition) are inputs; exhaust and work (translational motion) are outputs.

\'\'\'Component Form:\'\'\'

The general shape of this component is cylindrical. Like most cylinders, this component is axially symmetric around its z-axis. It is primarily a three-dimensional object with the following dimensions in centimeters: 3.5x3.5x3.3. The component weighs around 48 grams (this weight includes the piston and rod together, because they were not separable during the disassembly process). The overall shape of this component is directly correlated to its function because a combustion engine employs a piston-cylinder system.
This component is made from aluminum. This is the most common material for internal engine parts because of the factors that influence internal engine parts. Aluminum is a lightweight and relatively cheap metal, thus making it economically ideal for use in an internal combustion engine. This represents an economic factor of this component’s design. These facts also help increase the engine’s efficiency. Aesthetically, the component has a very fine surface finish on all of its exterior surfaces. This is due to the fact that the least amount of friction is needed within a piston-cylinder system as to maximize the work out.

\'\'\'Manufacturing Methods:\'\'\'

Investment casting and milling processes were most likely used to manufacture this component. The first evidence of this is the fact that this part is a fine and detailed internal component, which is usually what investment casting is used to make. Also, the component does not show any signs of parting lines, flash, or draft, all of which do not appear on investment casted parts. Finally, it is suspect of milling because of the very fine surface finish that exhibits symmetrical lines in its reflections, hinting at a drill-type milling machine used to shave down the rough surface from its cast. These manufacturing methods represent an environmental factor of the component’s design because the more efficient the cylinder’s interactions are within the combustion chamber, the less gas will be needed, and thus less emissions over the products lifespan.

\'\'\'Component Complexity:\'\'\'

Rating: \'\'\'2\'\'\'

Although this component is part of a rather complex process of interactions (the 2-stroke combustion cycle), it is not a particularly complex component. It is simply a hollow cylinder with a connecting rod going across its center (perpendicular to it’s z-axis) so it can be attached to the piston rod.

Rod

Rod.jpg


\'\'\'Component Function:\'\'\'

This component was chosen for the same reasons as the aforementioned component – its relevance to the overall function of the product. This component’s main function is to connect the translational motion harnessed by the piston to the rotational motion of the crankshaft. It functions in the same operating environment as the piston and is directly attached to the piston, as illustrated in the accompanying picture. In general, the flows associated with this part are as follows: work (translational motion) as an input and work (rotational motion) as an output.

\'\'\'Component Form:\'\'\'

The general shape of the component is linear, very similar to that of a two-sided wrench. It is axially symmetric around two of its axes and is primarily a two-dimensional part. The overall dimensions of the part are as follows in centimeters: 6.5x1.8x0.5. The component weighs around 48 grams (this weight includes the piston and rod together, because they were not separable during the disassembly process). The components shape is directly related to its function. It is primarily linear as to transfer motion in a two-dimensional linear fashion. Its wrench-like features are to accommodate for the connections it makes with the piston on its top end and the crankshaft on its bottom end.
This component is made from aluminum. This is the most common material for internal engine parts because of the factors that influence internal engine parts. Aluminum is a lightweight and relatively cheap metal, thus making it economically ideal for use in an internal combustion engine. This is an example of an economic factor of this component’s design. These facts also help increase the engine’s efficiency. Aesthetically, the component has a very fine surface finish all around. This is so the component can operate freely and balanced when it reaches very high operating speeds.

\'\'\'Manufacturing Methods:\'\'\'

Investment casting and milling processes were most likely used to manufacture this component. The first evidence of this is the fact that this part is a fine and detailed internal component, which is usually what investment casting is used to make. Also, the component does not show any signs of parting lines, flash, or draft, all of which do not appear on investment casted parts. Finally, it is suspect of milling because of the very fine surface finish that exhibits symmetrical lines in its reflections, hinting at a drill-type milling machine used to shave down the rough surface from its cast.

\'\'\'Component Complexity:\'\'\'

Rating: \'\'\'2\'\'\'

This component is not a very complex part at all. Although its interactions are complex (the same as those for the piston), it is essentially just a linear object that acts to transfer motion over a short distance.

Turbine

Turbine1-12.jpg Turbine2-12.jpg


\'\'\'Component Function:\'\'\'

This component was chosen for its direct relation to the product’s overall function – create a concentrated stream of air for landscaping purposes. The main function of this component is to create a concentrated airflow for the leaf blower to output. This is essentially the only function of this component, which is a relatively important function given the overall purpose of the product. The operating environment of this component is in an external housing from the motor, which takes in outside air and increases its velocity. In general, the flows for this component are as follows: air and work (rotational motion) are inputs; air at an increased velocity is the output.

\'\'\'Component Form:\'\'\'

The general shape of the component is circular, with blades coming up off of the circles plane. It is not axially symmetric and is primarily a three-dimensional object with the following dimensions in centimeters: 16.4x16.4x3.6. The component weighs around 138 grams. Its shape is directly related to its function. The turbine acts to physically accelerate airflow therefore it must hold some shape that can achieve uniform revolutions.
The component is made from plastic, a decision most likely based on the greater efficiency being achieved with a lighter turbine. This represents an economic factor because the more efficient the turbine blade is, the less gas is necessary to use the product and the more powerful it can become with the same size engine. Aesthetically, the component is relatively smooth, and black in color. The surface-finish in intended to maximize the airflow produced by the component and allows it to spin as freely and balanced as possible when operating as very high speeds. The overall design of this component represents a societal factor; the more concentrated and efficient the airflow is, the less likely this product is to blow leaves out of the user’s control, which is an essential function given the residential operating environment where consumers do not want to be disturbing neighbors with their landscaping waste.

\'\'\'Manufacturing Methods:\'\'\'

This component was most likely manufactured by injection molding. Evidence of this is in the trace amount of parting lines and riser marks visible on the component, as well as the fact that it is plastic, which is primarily injection molded.

\'\'\'Component Complexity\'\'\':

Rating: \'\'\'3\'\'\'

This component is simple at first glance, but in actuality rather complex. The numbers of calculations that factor into the specific dimensions of turbine blades are immense. They must be designed to maximize the components function considering numerous external factors. The component’s interactions, however, are rather simple, taking the rotational motion from the crankshaft and using it to spin turbine blades, thus accelerating airflow.

Cylinder

Cylinder1-12.jpg Cylinder2-12.jpg


\'\'\'Component Function:\'\'\'

This component was chosen for its relevance in the combustion cycle. The cylinder is the other necessary part of the piston-cylinder system. It is the chamber which houses the combustion chamber and within which the combustion process takes place. This component functions in an external environment, with all the relevant processes taking place inside of it. Combining the flows associated with the piston and rod, the cylinder’s flows are as follows: Air, fuel and heat (as the spark ignition) are inputs; work (rotational motion) and exhaust are outputs.

\'\'\'Component Form:\'\'\'

The general shape of this component is a rectangular cube with a cylinder hollowed out within. It has no notable axial symmetries and is primarily a three-dimensional part. Its dimensions are as follows in centimeters: 6.7x5.9x6.4. The components shape is related to its function because it holds the cylindrical piston with which the combustion process employs. Its external shape is used to increase the outside surface area using the rectangular fins as illustrated in the picture. This increase in surface area acts to expel the large amounts of heat that build up within the cylinder as a result of the combustion process. The component weighs around 282 grams.
This component, like most of the other functional combustion components, is made of aluminum. This is for the same manufacturing reasons mentioned for the piston and rod, including the maximization of efficiency and money by using a lightweight and cheap metal. Aesthetically the component has a rough surface finish on its external surfaces, but a very fine finish on its internal surfaces. This is for the same reasons noted for the piston, to decrease friction within the piston-cylinder system and to maximize work out. The same factors that influence the piston and rod design influence the design of this component because of its relevance to the combustion cycle.

\'\'\'Manufacturing Methods:\'\'\'

This part was most likely manufactured by die casting and milling. The evidence of die-casting is seen on the apparent parting line going around the entire middle of the exterior surface. The evidence of milling is seen in the internal surface of the component, which has a very fine surface finish like the exterior of the piston and rod.

\'\'\'Component Complexity:\'\'\'

Rating: \'\'\'3\'\'\'

This component is not that complex. It is a rectangular cube with an internal hollow cylinder. It also has one port on either side going from the external surface to inside the cylinder to be used for the intake and exhaust of the 2-stroke combustion cycle; it also has a port directly on the top for insertion of a spark plug. Other than that, this component does not perform any motion when operating and simply serves as a boundary for the piston-cylinder system.

Fuel Tank

Fueltank.jpg


\'\'\'Component Function:\'\'\'

This component was chosen for its importance in conjunction with the 2-stroke combustion cycle. This fuel tank holds one of the most important inputs of the combustion cycle – fuel – and must be designed to hold a specific amount of fuel for ideal operating time with ideal operating conditions (i.e. a tank too big would impede the users range of motion). This also represents an economic factor because a tank too big would frequently result in unused gas going bad over extended periods of time, which would make the user have to purchase more gas and waste the existing fuel that went bad. This component’s operating environment is external, and it performs no motion. In general, its flows include fuel being stored within it by the user, and being outputted as needed by the engine.

\'\'\'Component Form:\'\'\'

The general shape of this component is an oval, although it is really just a series of curved surfaces. It is axially unsymmetrical and is primarily a three-dimensional object, evident by its sole purpose to store a volume of liquid. It dimensions are as follows in centimeters: 14.8x6.4x7.5. The component’s shape is not exactly related to its function, except in the sense that it is shaped so as to conform to the overall shape of the product. The component weighs around 110 grams (with cap and internal tubing included).
The component is made out of plastic, most likely chosen for its commonality with such components. Also, because there is no reason to make a fuel tank out of metal for this scale motor. Aesthetically, the component has a relatively smooth surface and is a white-transparent color. The surface finish has no significance, however, the transparency of the color allows the user to see how much fuel is in the tank, a useful feature considering there is no fuel gauge on this type of product.

\'\'\'Manufacturing Methods:\'\'\'

This component is most likely manufactured by injection molding. The evidence of this manufacturing process is in the component’s parting lines, draft and the fact that it is plastic, which is primarily injection molded.

\'\'\'Component Complexity:\'\'\'

Rating: \'\'\'1\'\'\'

This component is probably one of the least-complex components of the product. It mounts onto the side of the product, has a threaded cap, and tubes for the retrieval of fuel by the motor through suction. The interactions of this component are also limited in complexity, being primarily from the motor drawing fuel through tubing and the user refueling.

Throttle Body

Throttle1-12.jpg Throttle2-12.jpg Throttle3-12.jpg


\'\'\'Component Function:\'\'\'

This component was chosen for its pivotal role in the combustion process. The two main inputs to the combustion cycle are air and fuel, which must be mixed according to specific ratios in order to achieve varying levels of engine output. The throttle body is the component that mixes these two inputs. Its operating environment is external, attached directly to the intake port of the cylinder. It features two levers, the choke and throttle, which control the air flow into the engine. It also features two nozzles that retrieve gas from the fuel tank through tubes. In general, its flows are as follows: Human signals, fuel and air are inputs; a fuel-air mixture is the output. The overall function and design of this component represents and environmental factor because air/fuel ratio’s too lean or too rich would result in increased emissions and decreased engine efficiency.

\'\'\'Component Form:\'\'\'

The overall shape of this component is a rectangular cube, although its surfaces feature various curves and openings. It is not axially symmetric, and is primarily a three-dimensional object with the following dimensions in centimeters: 4.5x2.9x3.8. The component’s shape is ideal for its functions because it acts as an intermediary between the cylinder and the cylinder’s inputs. Therefore, two flat surfaces on a generally rectangular cube shape allow it to sit flush between the cylinder and the air intake manifold. The component weighs around 109 grams.
The component is made from aluminum, once again, the most ideal choice for an engine component due to its relative low cost and light weight. Aesthetically, the component has very fine surface finishes on two of its sides, and a relatively rough surface finish on the remaining sides. The fine surface finishes are intentionally designed to allow the component to make flush contact with the cylinder and intake manifold, so as to keep the system air tight.

\'\'\'Manufacturing Methods:\'\'\'

The most probable manufacturing process for this component is die-casting and milling. The evidence of die-casting is seen on an external surface, as illustrated in the accompanying pictures, where a clear parting line runs down the middle of the side. Milling is evidenced by the very fine surface finishes apparent on two of the components external sides, and the fine tolerance holes made throughout the component to be used as ports for air and fuel, as well as component holes for the levers and tubes which also run through the component.

\'\'\'Component Complexity:\'\'\'

Rating: \'\'\'3\'\'\'

This component in and of itself is one of the most complicated components of the product. The air-fuel mixture of a combustion cycle must be very specific, and this component must be designed with very fine calibrations. Furthermore, the choke and throttle levers have very specific diameters and ranges of motion relative to each other, in order to allow the engine to run properly and efficiently during operation. Other than the components overall function, its interactions are rather simple – the input of two substances and then the output of one mixture.

Muffler

Muffler1-12.jpg Muffler2-12.jpg Muffler3-12.jpg


\'\'\'Component Function:\'\'\'

This component was chosen for its function relative to the product’s operation with regard to societal factors. The main function of this component is to expel the exhaust gases from the combustion chamber and decrease the noise level as much as possible. Furthermore, the components operating environment is external, attached directly to the exhaust port of the cylinder. This is a societal factor because a quieter product is more acceptable to be used in residential landscaping scenarios, and can be used at more times than a loud product. The flows associated with this product are exhaust gases going in and exhaust gases going out. It really only acts on the sounds waves that exit the combustion chamber as very high frequencies. The function and design of this component also represents an environmental factor, because the muffler acts to filter out emissions before the exhaust gases get expelled into the environment.

\'\'\'Component Form:\'\'\'

The general shape of this component is a rectangular cube. It is not axially symmetric and is primarily a three-dimensional object, with the following dimensions in centimeters: 6.7x6.4x4.0. The components shape is mostly due to its location relative to the overall design of the product. It must sit in a very tight space, directly attached to the cylinder. For this reason, the rectangular shape is ideal given the general shape of the products various other components. The component weighs around 172 grams.
This component is made out of aluminum, which as mentioned several times is the ideal material for use on engines. Aesthetically, the component has a relatively smooth surface finish, although this does not seem to be intentionally designed this way. Aside from the need for the component to sit flush against the cylinder on only one side, the surface finish appears to be a result of the manufacturing process used.

\'\'\'Manufacturing Methods:\'\'\'

This component was most likely manufactured by the process of drawing. This is evidenced by the smooth surface finish compared to the die-casted parts, without any indication of milling. Also, there is a punched out section, as illustrated in the accompanying pictures, that appears to have been made by stretching of the aluminum over a mold. The final evidence of drawing is in the folded over lip that connects the two sides of this component, as illustrated in the accompanying pictures, which is usually found in drawing processes.

\'\'\'Component Complexity:\'\'\'

Rating: \'\'\'2\'\'\'

This component performs a relatively simple task, and likewise, has relatively simple interactions. However, the components internal components are more complex than it appears, because they must be designed to filter out the noise pollution of the combustion chamber while not hindering the exhaust flow.

Solid Modeled Assembly

The CAD program used to create these 3D models was Solid Works. The group chose this program because one member already had extensive experience with it and is taking a course on it. The group picked the piston assembly because the parts are small and well-defined. The piston assembly is also a very important component in the overall system.

Individual Piston Assembly Components

Solid Models of the Piston Assembly
Part Name 3D-Model of Part
Piston
Pistonmodel.jpg
Piston Bottom
Pistonmodel2.jpg
Pin
Pin1-12.jpg
Connecting Rod
Rod1-12.jpg
Piston-Rod Assembly
Pistonrod2.jpg
Crankshaft
Crankshaftmodel.jpg

Finished Piston Assembly:

Assembly1-12.jpg Assembly2-12.jpg


Engineering Analysis

Design Revisions

Revision 1

\'\'\'Fig. 3-14\'\'\'
\'\'\'Fig. 3-14\'\'\' The handle sits in a nonuser-friendly place
The handle of the leaf blower could be upgraded in design by changing the shape and angle at which it sits when in the user’s hand. The weight of the leaf blower doesn\'t sit evenly in the user’s hand as the pressure sits in mostly the back part of the hand, making it somewhat uncomfortable. It also isn\'t shaped to fit in the user’s hand as well as it should be. More contours would probably make this handle more comfortable for the user and more easily usable for longer periods of time. Also by counterbalancing the product, it wouldn\'t feel as awkward to hold and again would be easier to use for longer periods of time. These ergonomic changes would be a societal factor design change to better improve the usage by the user.

Revision 2

\'\'\'Fig. 3-15\'\'\'
\'\'\'Fig. 3-15\'\'\' The plastic used on the casing could be upgraded
The plastic casing around the engine is used to protect the engine and control components from events such as bumps and drops. The plastic casing is a sturdy material made from a thick and dense type of plastic. This casing could be upgraded in design by changing the material or type of plastic used. The current material could be changed to a plastic or a synthetic that provides the same strength required for drops or bumps but uses less material. This design change would be an Environmental factor design change to reduce the amount of waste or thinking about the end life of the plastic and the leaf blower. This could be less cost efficient and would have to be considered as what would be a better trade off in the design goals.

Revision 3

\'\'\'Fig. 3-16\'\'\'
\'\'\'Fig. 3-16\'\'\' The engine could be changed to become a multi-source product
The engine could be modified to allow an adapter that would let the user plug the device into and electrical source to allow the user to have a choice of which energy source they would like to use. This would allow the user to be more environmentally friendly. The exhaust would be heat instead of other more harmful pollutants. This would also allow the user easier access of power during gas shortages. This design change would have global, environmental and economic factors, allowing for many users in many different places with access to different energy sources to use it, allow users to be more environmentally friendly with no harmful emissions, and allow for a use of a cheaper source of energy.