Group 4 - Toro Snowblower 1 - Gate 3

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Contents

Introduction

Below is group four’s gate three, product analysis. In this section of the project, we studied the Toro Snowblower on a component and subsystem level. The report is detailed as follows: cause for corrective action (including problems we faced, and solutions we propose to those problems), a component summary (brief overview of all the parts of the Toro Snowblower), a product analysis (an in-depth look at the components that make up the engine), an engineering analysis (looks at a way to make design decisions), and design revisions (changes that would make the Toro Snowblower more marketable from our perspective, backed up with solid modeling to serve as a reference). The objective of this gate is to outlay an analysis of our product in a more detailed manner, along with a reflection on problems that we faced and solutions to those problems.

Product Management

Cause For Corrective Action

Thus far in the project, our group has worked well together with little conflict. One of the toughest challenges we have encountered though, is scheduling a time that everyone can meet. As the semester has progressed, it appears everyone has gotten busier with classes and work. To address this problem, we have worked to find times when the majority of the group members can meet. Normally for short meetings (problems we have encountered, deadlines that are approaching, and general concerns), we have found that meeting right after Introduction to Mechanical Engineering in the lecture hall, Knox 104, works quite well because everyone is in one place. For longer meetings, we have been meeting at night during lab times. Sometimes, conflicts arise with the longer meetings. To solve this we plan to use Google Calendar so all of us are aware of when everyone can meet outside of class. Another challenge we have faced is revisions. No one person is specifically designated to double check that all the information that was requested is posted on the wiki and that all the information makes sense. To solve this problem, we set one group member in charge of re-reading each assignment and double check that everything is posted that is required. All work was received on time, and posting to the wiki has been an ongoing process. Last minute posting has been a problem in the past because formatting the wiki takes a large chunk of time. To address this problem, when we were finished a section, we directly posted it to the wiki, instead of waiting until the night before. This also has lead to better internal deadlines. But as a whole, our group has worked fairly well together.

Product Archaeology

Component Summary

Table 1: Component List
Component Number Image Name Function Material Manufacturing Process Used Model/Part Number Quantity
1
Muffler
Figure 1: The muffler.
Muffler Muffle sounds from the engine. Steel because it is magnetic. Die cast because there is a seam underneath the fold. 801250 1
2
Muffler Screws
Figure 2: The two screws for the muffler.
Screw Hold muffler in place. Steel because it is magnetic. Die cast because there are riser marks. 801251 2
3
Cylinder Assembly
Figure 3: The cylinder assembly.
Cylinder Assembly Acts as a housing for the crankshaft and piston. Aluminum because it is not magnetic and aluminum is typically used for cylinder assemblies. Die cast because it has draft angles. 801322 1
4
Cylinder Head
Figure 4: Cylinder Head.
Cylinder Head House the combustion chamber. Aluminum because it is not magnetic and aluminum is typically used for this part. Die cast because it has draft angles. 801283 1
5
Stud
Figure 5: Stud that holds the cylinder head in place.
Stud Hold the cylinder head in place. Steel because it is magnetic. Die cast because it has riser marks. 801265 2
6
Piston Assembly
Figure 6: Picture of the Piston Assembly.
Piston Assembly Provide mechanical energy to the crank shaft. Aluminum because it is not magnetic and aluminum is typically used for this part. Turned because it is radially symmetrical and has horizontal striations. 801279 1
7
Crankshaft
Figure 7: Crankshaft.
Crankshaft Convert linear mechanical energy from the piston into rotational mechanical energy. Steel because it is magnetic Turned because it is radially symmetrical and has horizontal striations. 801220 1
8
Flywheel
Figure 8: Flywheel.
Flywheel Conserve the momentum of the engine and steadies the rotation of the crankshaft during the combustion process. Steel because it is magnetic. Die cast because it has draft marks. 801246 1
9
Cup-Flywheel
Figure 9: Cup for the flywheel.
Cup-Flywheel Help start the engine. Steel because it is magnetic Die cast because it has riser marks. 801235 1
10
Housing-Blower
Figure 10: Housing for the flywheel.
Housing-Blower Shields the flywheel. Steel because it is magnetic Die casting because there are gate marks. 801236 1
11
Starter-Rewind
Figure 11: Starter-Rewind for the manual start.
Starter-Rewind To help start the engine and rewind the starter cord. Steel because it is magnetic. Die casting because there are gate marks. 801242 1
12
Starter-Motor
Figure 12: Starter motor for the electric start.
Starter-Motor Starts the engine using electrical power. ABS Plastic because it is durable and impact resistant. Injection molding because there is a parting line. 801247 1
13
Upper Handle
Figure 13: Upper Handle.
Upper Handle Handle for the user to grasp onto while using the product. Steel because it is magnetic. Extruded because it is a bent pipe. 95-2667 1
14
Lower Handle
Figure 14: Lower Handle.
Lower Handle Connects to the upper handle and the main body of the snowblower. Steel because it is magnetic. Extruded because it is a bent pipe. 55-9121-01 1
15
Bail
Figure 15: The Bail.
Bail Used to engage the engine. Steel because it is magnetic. Drawn because it is a metal wire bent into shape. 71-5120-01 1
16
Cable Clutch
Figure 16: Cable Clutch.
Cable-Clutch Connects the Bail to the clutch. Steel because it is magnetic. Drawn because it is a steel cable. 94-9922 1
17
Screw
Figure 17: Screw to fasten the upper and lower handles together.
Screw Fasten the upper handle to the lower handle. Steel because it is magnetic. Die cast because it has riser marks. 17-9424 3
18
Fuel Tank
Figure 18: Holds the fuel mixture.
Fuel Tank Hold the gas-oil mixture used in combustion. Polyethylene because it is durable and resistant to gasoline and corrosion. Injection molding because it has parting lines. 94-9920 1
19
Frame
Figure 19: Frame of the snowblower.
Frame Attaches the whelks to the rest of the body and supports the other components. Steel because it is magnetic. Die cast on the brackets because they have have parting lines, the smaller cylinder rod is drawn and the larger cylinder pipe is extruded. 95-1892 1
20
Wheel
Figure 20: Wheels of the snowblower.
Wheel Allows the snowblower to be easy moved. ABS plastic because it is durable and has to support some of the weight of the snowblower and rubber for the tire to provide traction in slippery winter conditions. Injection molding because there are parting lines. 66-6510 2
21
Nut-Push
Figure 21: Nut-push to hold the wheel onto the frame.
Nut-Push Holds the wheels onto the frame without restricting their ability to spin. Steel because it is magnetic. Die cast because it has riser marks. 32112-14 2
22
Righthand Sideplate
Figure 22: Righthand Sideplate.
Righthand Sideplate Cover the right side of the assembly. Steel because it is magnetic. Shaped because it is too thin to be die cast. 55-8840-01 1
23
Housing
Figure 23: Snowblower Housing.
Housing Contains the rotor and helps direct snow through the chute. ABS plastic because it is durable. Injection molding because it has parting lines. 55-8700 1
24
Ring-Chute Support
Figure 24: Ring-Chute Support.
Ring-Chute Support Supports the chute and connects the chute to the housing. Steel because it is magnetic. Die cast because it has riser marks. 55-8921-01 1
25
Chute Gear-Ring
Figure 25: Chute Gear-Ring.
Chute Gear-Ring Locks the chute in place so it does not move from side to side while snow is running though it and supports the chute. ABS plastic because it is durale and strong enough to be rotated. Injection molding because there are parting lines. 71-4950 1
26
Chute Handle-Control
Figure 26: Handle control for the chute.
Chute Handle-Control Allows the user to turn the chute. ABS plastic because it is durable to resist the moment provided by the user. Injection molding because there are riser marks. 94-9914 1
27
Chute-Discharge
Figure 27: Chute-Discharge.
Chute-Discharge Direct snow flow up into the chute deflector from the rotors. Steel because it is magnetic. Sheet of metal that was shaped into a rounded shape with holes stamped out and the sides crimped. 60-8690-01 1
28
Chute-Deflector
Figure 28: Chute-Deflector.
Chute-Deflector Changes the direction of the snow from straight up to at an angle with the ground. ABS plastic because it needs to be strong enough to withstand the snow hitting it. Injection molding because there are parting lines. 56-2680 1
29
Rotor
Figure 29: Rotor.
Rotor Connects to and spins the rotor blades. Steel because it is magnetic. The cylinder is extruded and the two end brackets are stamped. 55-9202-01 1
30
Rotor-Blade
Figure 30: Rotor blade.
Rotor-Blade Scoops the snow into the chute and provides some propulsion to the snowblower. Rubber for hardness and fabric to help hold it together. The rubber and fabric are either glued together with an adhesive or the rubber is melted and impregnated into the fabric. 88-0771 2
31
Wa-Housing
Figure 31: Wa-Housing.
Wa-Housing Connects to the scraper to help get all of the snow up and onto the rotor blades. Steel because it is magnetic. Shaped and crimped from a sheet into its final form 55-9220-01 1
32
Scraper
Figure 32: Scraper.
Scraper Allows the snowblower to pick up as much of the snow off the ground as possible. ABS plastic because it needs to be durable and strong since it is scraping against the ground. Injection molded because it has a parting line. 55-8760 1
33
Lefthand Sideplate
Figure 33: Lefthand Sideplate.
Lefthand Sideplate Cover the left side of the assembly. Steel because it is magnetic. Shaped because it is too thin to be die cast. 55-8851-01 1
34
Rotor Pulley Asy
Figure 34: Rotor Pulley Asy.
Rotor Pulley Asy Connected to the crankshaft and rotates the rotor by transferring rotational energy coming from the engine to the rotor via a belt and pulley. ABS plastic because it is strong enough to rotate fast and a steel center because it is magnetic. Injection molding because it has riser marks. 60-9320 1
35
Belt-Drive
Figure 35: Belt-Drive.
Belt-Drive Transmit energy from the engine to the rotor pulley. Rubber for friction and hardness and fabric to hold it together. Fabric was impregnated with melted rubber and the rubber was molded into the correct shape. 55-9300 1
36
Engine Pulley
Figure 36: Engine Pulley.
Engine Pulley Connects the crankshaft to the pulley. Steel because it is magnetic. Die cast because it has gate marks. 55-9180 1
37
Mudflap
Figure 37: Mudflap.
Mudflap Prevent mud and debris from shooting back and hitting the user. Plastic Injection molding because there are riser marks. Unknown 1
38
Shield-Heat
Figure 38: Heat shield that covers the engine.
Shield-Heat Covers the engine and allows for airflow. Steel because it is magnetic. Stamped into its shape because the part is too thin to be die cast. 94-9924-01 1
39
Upper Shroud
Figure 39: Upper Shroud.
Upper Shroud Covers all of the components to protect them from the elements and the user from hurting him/herself. ABS plastic because it is durable. Injection molding because there are gate marks. 94-9925 1
40
Lower Shroud
Figure 40: Lower Shroud.
Lower Shroud Covers the components to protect them from the elements and the user from hurting him/herself. ABS plastic because it is durable. Injection molding because there are gate marks. 94-9919 1
41
Plate
Figure 41: The user interface plate.
Plate Provides a place for the user interface functions. ABS plastic because it is durable. Injection molded because there are gate marks. 94-2569 1
42
Armature-Magneto
Figure 42: Armature-Magneto.
Armature-Magneto Generates a current which it provides to the spark plug. Rubber outside and steel inside because it is magnetic. The steel appears to be a number of thin stamped sheets stacked together and the rubber acts as a casing and may be molded around it. 801268 1
43
Fuel-Line
Figure 43: Fuel Line.
Fuel-Line Provides a path for the fuel to flow from the fuel tank to the engine. Rubber because it is flexible. Extruded because it is a hollow hose. 49-2482 1

Product Analysis

Interaction Scale

Simple: A simple interaction consists of a single physical interaction between two components to perform a single function.
Semi-complex: A semi-complex interaction consists of one or more physical, electrical, etc… interactions between two or more components, may help to perform one to a few functions.
Complex: A Complex interaction consists of one or more physical, electrical, chemical, etc… interactions between two or more components in which require specific component detail for the interaction(s) to work and perform the desired function(s). This interaction may help to perform several functions. (ex: inner workings of the muffler interacting with the sound and exhaust from the engine.)

Complexity Scale

Simple: A simple component is described as a component that performs a single function or trivial functions and has little detail in design (including, but not limited to components geometry, features, etc.). A simple component also does not require any special material property to function properly. A simple component may have also been manufactured using a simpler process such as a shaping.
Moderate: A moderately complex component is described as a component with one or more functions in the scheme of the engine, moderate detail in design (including, but not limited to component geometry, features, etc.). A moderately complex component also does not require any special material to function properly but may be manufactured using a more “complex” process such as casting/molding, but it does not necessarily have to be.
Complex: A complex component is described as a component that performs one or more essential functions in the engine. They are also are of a more complex geometry than other components and possibly required a manufacturing process unique to those of other, simpler, components. A complex component may also have required a special material for it to perform its function properly.

How This Scale Was Defined

In determining the complexity of each part, factors such as material, detail, manufacturing method, shape, and functionality were all taken into consideration. Setting the scale as simple, moderate, and complex helps to easily portray how complex a given part was without being too general. In reading the definition of each level of complexity and then comparing it to a corresponding part, one can easily see what causes the scale to increase from simple to moderate to complex.

Muffler

Muffler
Figure 44: The muffler.
Component Function

To muffle the sound coming from the motor. Muffler is not necessary for the rest of the engine to run. Exhaust and sound waves move through it and exit the machine through the muffler. It functions in the outside environment (mainly cold, snow, wet environment) and also in the exhaust environment (hot, steamy environment).

Component Form

The general shape is a rectangular prism. It is not symmetrical. It has two main holes and 2 small screw holes on the side that go all the way through to the other side (two holes are also located there that the screw would go through. There is a center seam linking the right and left together. There are ridges along one side running along the top. It is 6.75 inches by 3.25 inches by 4.75 inches. The outer shape has a couple of functions that help the muffler perform its main task of muffling noise produced by the engine. First it holds the mufflers inner workings which usually consist of two or more pipes that have perforations, a resonator chamber and an intake and outtake system. It also ensures that the sound and exhaust are put through the perforations and resonator chamber before being expelled through the outlet. It is box shaped because it is the appropriate shape to house the inner workings. It weighs approximately 6 lbs. It is made of steel because it is magnetic and slightly rusted. It is made of steel because it is cheap and weight is not a factor. A metal is needed to muffle the sound because the body of the muffler has to absorb some of the pressure pulses of the sound. The factors that went into making it out of steel are that steel is cheap and widely available. A global factor concerning steel is that it is widely available in most geographical locations. A global factor is that the laws for steel production regulation concerning air pollution and emissions vary from region to region. The laws concerning emissions specific to the production of steel in the United States is a societal factor because it pertains to the health and environmental concerns caused by these emissions. Another societal as well as an environmental factor of steel is the pollution generated from the creation of steel which can be detrimental to ones health and to the surrounding environment and ecosystems. Another environment factor concerning steel would be that it is made from iron which involves mining and the depletion of the earth of its natural resources. An economic factor concerning steel is that it is very cheap to manufacture; modern mining and melting are fairly cheap and efficient processes. The component has no aesthetic purpose. The muffler is polished and coated to help prevent rust and decay (functional). The color of the component is grey and not colored because the snowblower is not meant to be taken apart and viewed for aesthetics.

Manufacturing Methods

The muffler was die cast because there is a lip which hides a seam. Steel is easy to die cast. The shape of the muffler is simple and therefore, die casting would be ideal. Because the part is medium sized, produced on a massive scale, and has a good surface finish, die casting would be the cheapest method and therefore, both societally and economically efficient. An economic factor of die casting is that it is fairly reasonably priced for mass produced parts, the only high cost is the initial capital cost in making the die.

Component Complexity

The component is not very complex on the outside. It is simple because it is a basic shape with very few features. With die-casting you can only make simple components. The material choice has nothing to do with complexity. The appearance and geometry of the part, make the part very simple. Overall the complexity of the outer shell of the muffler is not drastically impacted by its inner workings as they mainly just determine the size of the outer shell needed to hold in all of the inner workings. The inner workings of the muffler are quite complex for the sound waves, but not very complex for the exhaust. The sound wave interaction is complex because the sound waves enter the muffler and get bounced around in various tubes to decrease the noise of the snowblower. The exhaust interaction is not very complex because it flows through the system steadily. The interactions are complex because sound bounces around in the perforations and resonator chamber, and the exhaust flows through it.

Cup-Flywheel

Cup-Flywheel
Figure 45: The Cup-Flywheel.
Component Function

The purpose of the cup to rotate. The manual start is connected to the cup and starts rotating the fly wheel which gets the piston moving. The component helps to perform multiple functions because the manual start is connected to the cup which starts the flywheel and starts the engine. The flows that are associated with the cup are kinetic energy flow because the cup transfers the manual start turning into the rotating of the flywheel. The cup functions in an isolated environment inside the snow blower; it will heat up with the engine and the heat that is transferred between the metals, but the outside air does not have contact with the cup.

Component Form

It is a three dimensional hollow cylinder with the top cut off. The top lid is flattened to form a brim. Under the brim on the cylindrical part there are slits. There is a rectangular nub/hole along the bottom edge. There is a hole is the center with a raised star burst around the whole in the inside of the cup. It is symmetrical (except for the bottom nub/hole). The cup is 2 inches tall, the brim has diameter of 3 inches, and the bottom has a 2.4 inch diameter. The shape is coupled with the function since it must be able to freely and easily rotate. It weighs roughly 1 pounds. The component is made from steel because it is magnetic. Manufacturing decisions did not influence the material choice. A strong and stable metal is needed for this component to function since it must constantly take the stress and forces involved in the use of the manual start and the initial rotation of the flywheel. A global factor concerning steel is that it is widely available in most geographical locations. A global factor is that the laws for steel production regulation concerning air pollution and emissions vary from region to region. The laws concerning emissions specific to the production of steel in the United States is a societal factor because it pertains to the health and environmental concerns caused by these emissions. Another societal as well as an environmental factor of steel is the pollution generated from the creation of steel which can be detrimental to ones health and to the surrounding environment and ecosystems. Another environment factor concerning steel would be that it is made from iron which involves mining and the depletion of the earth of its natural resources. An economic factor concerning steel is that it is very cheap to manufacture; modern mining and melting are fairly cheap and efficient processes. The component does not have an aesthetic purpose because it is not intended to be seen. It is grey because it is metal and it is not painted because it is not intended to be seen. The component is chromed to reduce erosion and other wear and tear due to constant rotation and stress from the manual start for the initial rotation of the flywheel. The chromed surface finish is for functional reasons because the part is not supposed to be seen.

Manufacturing Methods

It is a shaping operation because of the smooth finish. It appears to be stamped because the side slants and center star appear to be stamped out and then the part appears to be shaped into a circle. Material choice had no impact in being stamped because most materials can be stamped. Shape did impact the method selected because the part is simple and not complex, shaping was the easiest method to get a cup shape with minimal work. Economic factors influenced this decision because stamping is cheap for simple parts. A global factor is that stamping can be preformed anywhere on the globe and is not limited by geography.

Component Complexity

It is not complex because the cup is a simple shape with very little features. The function of the cup makes the part simple because the needs to rotate which in not a very intricate process. Stamping the cup ensures that the component is very simple. The geometry and appearance of the cup makes it simple because it has very few features. The material choice has no impact on the complexity of the object. The interactions are simple because it rotates the flywheel and is rotated by the manual start.

Flywheel

Flywheel
Figure 46: The Flywheel, Part A on the left and Part B on the right.
Component Function

The flywheel locks the engine to the transmission shaft and causes the two pieces to spin at the same speed. It performs multiple functions because it has to turn the transmission shaft which helps make the engine work. Kinetic energy flows and magnetic flows are associated with the flywheel. It functions in inner environment of the snowblower. The environment is hot because the tips of the steel are melted due to friction. It also acts as a way for the spark plug to obtain the energy to form a spark. The flywheel has a magnet on its side, that when rotating, goes by the Armature-Magneto and induces a magnetic field that causes current and eventually voltage that will cause a spark. Therefore the flywheel, along with the Armature-Magneto, acts as an energy source for the spark plug.

Component Form

The component is two three-dimensional cylinders: (a) one that has a smaller diameter, has a key hole, four holes all the way through, nine rivets holes on the top, ten rivet holes on the bottom, more mass, is thicker and magnetic with gears sticking out of it (that are melted); (b) the other is thinner, has a main hole through the center with three smaller holes on the outside frame, has a larger diameter, less mass, and not magnetic (even though it says magnetic). Dimensions of components: (a) 6.75 inch diameter, 2 inches height from top of gear; (b) 7.4 inch overall diameter, 1.25 inch outside frame length, 0.5 inch height. The shape acts as a gear and needs to be circular in order to turn. Weight: (a) roughly 15 pounds; (b) roughly 3 pounds. Material: (a) is made of steel because it is magnetic; (b) is aluminum because it is not magnetic and not rusty. Manufacturing decisions did not influence the choice of aluminum because die casting can be done with most metals. (a) A strong and stable metal is needed for this to function because it must be able to withstand constant rotation and heat. Also, it must have magnetic properties to help hold the magnets in place. (b) This piece must also be made of a strong and stable metal because it must also withstand rotation and heat. It must also have no magnetic properties so it does not interfere with the flywheel-magneto interaction. (a) A global factor concerning steel is that it is widely available in most geographical locations. A global factor is that the laws for steel production regulation concerning air pollution and emissions vary from region to region. The laws concerning emissions specific to the production of steel in the United States is a societal factor because it pertains to the health and environmental concerns caused by these emissions. Another societal as well as an environmental factor of steel is the pollution generated from the creation of steel which can be detrimental to ones health and to the surrounding environment and ecosystems. Another environment factor concerning steel would be that it is made from iron which involves mining and the depletion of the earth of its natural resources. An economic factor concerning steel is that it is very cheap to manufacture; modern mining and melting are fairly cheap and efficient processes.
(b) A global factor concerning aluminum is that it is widely available in most geographical locations. A societal factor of aluminum is that the pollution generated from the creation of aluminum that can be detrimental to ones health. An environment factor concerning aluminum would be that it involves mining and the depletion of the earth's natural resources. An economic factor concerning aluminum is that it is very cheap to manufacture; modern mining and melting are fairly cheap and efficient processes.

There are no aesthetic properties for this component. It has no aesthetic purpose. It is grey because it is not meant to be seen and metal is grey. (b) is chromed to reduce erosion and other wear and tear due to constant rotation and is functional.

Manufacturing Methods

Both are die cast because they have draft angles. Steel and aluminum are easy to die cast and die casting is a cheap method for mass production. Material choice impacted this decision because metal is easy to die cast. The shape impacted it because the teeth make the part semi-complex and die cast is the best method to make this feature. Because the part is medium sized, produced on a massive scale, and has a good surface finish, die casting would be the cheapest method and therefore, both societally and economically efficient. An economic factor of die casting is that die casting is fairly reasonable for mass produced parts, the only high cost is the initial cost to make the die. A global factor is that die casting can be done globally.

Component Complexity

(a) The component is complex. It has gears that jut out of the component, and multiple holes and different layers. The component's function makes the part complex because the placement of the magnet, gears, and layers of the product have to be precisely placed since they impact the function of the product. The geometry of the component does not enhance the components complexity since the overall shape is a circle which is not complex, but the geometric features of the component make it complex (the gears, layers, holes, etc.). The material choice makes it complex because the choice of steel, although it is fairly common, has a magnetic property that is essential for the components function. The appearance does not contribute to the complexity because is not aesthetically pleasing because it is not meant to be seen by the consumer. Manufacturing the component by die-casting does not enhance the complexity because the component being die-cast does not change the overall complexity; it does not enhance appearance, material selection, geometry, or function. The interaction is complex because it rotates at a specific speed so it interacts with the magneto to act as a battery to the engine.
(b) The component is not complex. It is a fairly ordinary circle with gear ridges and fastening holes. The components function makes the part simple because it sits on top of the more complex flywheel and turns. The geometry is simple and therefore makes the part simple. The material selection makes the part simple because steel is fairly ordinary. Appearance does not make it complex because it has no added aesthetic properties to factor into the complexity. The manufacturing choice does not make it complex because the part is not complex, and die-casting the part is not going to enhance the complexity. The part has simple interactions because it rotates and causes the rotation of an additional component.

Cylinder Assembly

Cylinder Assembly
Figure 47: The Cylinder Assembly, Part A on the left, Part B on the right.
Component Function

The two parts function to hold the flywheel in place and to house the crankshaft. (b) functions as a heat sink, houses the piston, and also is connected to the exhaust and intake systems. The two parts together help to perform multiple functions because the two house the flywheel that causes the spark which ignites the fuel which causes the piston to move up and down. Also part (b) helps to function with the exhaust and intake systems. Flows: mechanical kinetic energy from the rotational energy of the flywheel which sits on top of the two parts and turns the crank shaft transferring kinetic energy to the piston that moves back and forth; flow of fuel going into the system and exhaust coming out. The two parts function in an isolated environment inside the snow blower; they heat up due to the kinetic energy, but the outside air does not have contact with the two parts.

Component Form

(a) The general shape is a three dimensional triangle. The part is asymmetrical, with nine wholes all the way through, three holes not all the way through, five support cylinders, a hole in the top rim that the flywheel sits in, on the inside: chromed inside housing. The component is: 6.5 inches high, 8.5 inches length at base, 5.25 inch length at middle, 3.25 inch length of top, 4.1 inch depth at base, 1.1 inch depth at top. The shape impacts function because the top has to hold the flywheel, the middle has to house the crankshaft which has to be a certain shape so the shaft fits. Roughly weights three pounds and is made of aluminum because it is lightweight and not magnetic. Manufacturing decisions did affect the material choice because the part cannot be magnetic because it cannot interfere with the flywheel that creates the spark, so it cannot be steel. The material needed to perform the function has to be non-magnetic so the flywheel can easily rotate and create the starter spark. Global factor concerning aluminum is that it is widely available in most geographical locations. Societal factor of aluminum is that the pollution generated from the creation of aluminum that can be detrimental to ones health. An environment factor concerning aluminum is that it involves mining and the depletion of the earth's natural resources. Another environmental factor would be that the production of aluminum is detrimental to the environment. An economic factor concerning aluminum is that it is very cheap to manufacture; modern mining, melting, etc. are fairly cheap and efficient processes. The component has no aesthetic properties or purpose because the component is not suppose to be viewed by the consumer. The component is grey, unpolished except for the chromed crank shaft housing, because it is not meant to be viewed be the consumer and doesn’t have to be flashy. The purpose of the chrome is to help protect the crankshaft housing from corrosion because the housing contains the piston which is vital for the function of the engine.

(b) The general shape of b is a three dimensional square with added features. Notable properties: it has a heat sink, the inside is polished and chromed, the piston hole is polished and chromed, it has 3 black rubber spacers, it has an intake hole that is smaller, it has larger exhaust hole, it has a side wing. The component is asymmetrical. The heat sink has measurements of: 4.75 inch height, 3.75 inch width, 2.4 inch depth. The piston housing has a diameter of 2.5 inches. The inner housing has a length of 5 inches by 5.1 inches at its max width by 1.25 inch radius of larger side, .75 inch radius of smaller side. Height of wing 7.25 inches, width 2.5 inches. The components shape impacts function: the inner housing has to be that shape because it has to house the crank shaft which has a specific shape, the piston housing has to be cylindrical, the heat sink has to look like it does because the increased surface area expels the heat at a faster rate. It weighs about 10 pounds. The component is made of made of aluminum because it is not magnetic. Manufacturing decisions did affect the material choice because the part cannot be magnetic because it cannot interfere with the flywheel that creates the spark, so it cannot be steel. The material needed to perform the function has to be non-magnetic so the flywheel can easily rotate and create the starter spark. A global factor concerning aluminum is that it is widely available in most geographical locations. A societal factor of aluminum is that the pollution generated from the creation of aluminum that can be detrimental to ones health. An environment factor concerning aluminum would be that it is made that involves mining and the depletion of the earth's natural resources. Another environmental factor would be that the production of aluminum is detrimental to the environment. An economic factor concerning aluminum is that it is very cheap to manufacture; modern mining, melting, etc. are fairly cheap and efficient processes. The part has no aesthetic properties, it is not made to be appealing to ones eye because consumers are not suppose to see it. It has no aesthetic purpose because consumers are not meant to see it. The component is grey because it is metal and doesn’t need to be flashy, the chrome protects the crankshaft housing and the piston housing from corrosion. The outside of the component is not finished. All the aesthetic properties the component has are for functional reasons.

Manufacturing Methods

Both parts are die cast because there is a center seam, the part is mass-produced, and its complexity is within the capabilities of the die casting process. Aluminum is easy and cheap to die cast. The shape also impacted the choice of using the die cast process just for the sole reason that the part was complex enough but not too complex to use die casting. An economic factor of die casting is that die casting is fairly reasonable for mass produced parts, the only high cost is the initial capital cost to make the die. A global factor is that die casting is widely used globally. An environmental factor is that the creation of the mold causes pollution. (a) The component is moderately complex. It has gears that jut out of it, and multiple holes and different layers. The component's function makes the part moderately complex because the placement of the magnet, gears, and layers of the product have to be precisely placed since they impact the function of the product. The overall shape of a circle is not complex, but the geometric features of the component make it complex (the gears, layers, holes, etc.). The material choice and appearance do not make it complex because the choice of material of steel is fairly common and the appearance is not aesthetically pleasing because it is not meant to be seen by the consumer. Manufacturing the component by die-casting does not enhance the complexity because of the component being diecast does not change the overall complexity, it does not enhance appearance, material selection, geometry, or function.

Component Complexity

(a) It is very complex because it has numerous features that are extruded from the main frame and has numerous functions. The function does impact complexity because the different features on the main frame help to serve different functions within the engine. Geometry plays into the complexity because many of the features are either extruded from the main frame or imprinted into it which makes the component complex. The material choice does not impact complexity because aluminum is a fairly common metal. Aesthetics do not play into the complexity because the part is not meant to be viewed by the consumer and has no aesthetic features. Manufacturing the component by die casting does not enhance the complexity because of the component being die cast does not change the overall complexity, it does not enhance appearance, material selection, geometry, or function. The interactions are simple because the part houses the crankshaft and supports the flywheel.
(b) It is very complex because it has numerous features that are extruded from the main frame and has numerous functions. The function does impact complexity because the different features on the main frame help to serve different functions within the engine. Geometry plays into the complexity because many of the features are either extruded from the main frame or imprinted into it which makes the component complex. The material choice does not impact complexity because aluminum is a fairly common metal. Aesthetics do not play into the complexity because the part is not meant to be viewed by the consumer and has no aesthetic features. Manufacturing the component by die casting does not enhance the complexity because of the component being die cast does not change the overall complexity, it does not enhance appearance, material selection, geometry, or function. The interactions are semi-complex because it houses the crankshaft and piston and then also serves as a heat sink.

Head-Cylinder

Head-Cylinder
Figure 48: The Head-Cylinder.
Component Function

The component houses the spark plug and the combustion chamber. When the fuel is ignited, the combustion chamber portion forces the piston to move because the gas is expanded. The component helps to perform multiple functions within the engine. It gives the engine the initial spark to start the motion. It also helps to create the motion of the piston. The component is involved in energy and signal flow. The spark plug gets an electrical signal and the combustion chamber is involved in the flow of kinetic energy. The component functions in an isolated environment inside the snow blower; the component heats up due to kinetic energy, but the outside air does not have contact with the two parts.

Component Form

The general shape is a rectangular prism. Notable Properties: It has a heat sink on the top portion that helps to dissipate help from the combustion process. It has four holes for bolts that go all the way through and a hole for the spark plug on the top portion, and then one hole on the side that juts out from the main frame. The bottom side has a semi sphere indent that serves as a combustion chamber. The part is symmetrical except for the side screw hole that juts out of the main frame. The length is 3.75 inches, 3.75 inch width, 1.75 inch height at highest peak, and 1.25 inches at its lowest peak. The shape is coupled with the function because the bottom has to be a semi sphere so the combustion chamber lines up with the piston chamber, the top has to be a heat sink to dissipate heat from the engine. The component weighs roughly 3 pounds. The component is made of aluminum. Manufacturing decisions did affect the material choice because the part cannot be magnetic because it cannot interfere with the flywheel that creates the spark, so it cannot be steel. The material needed to perform the function has to be non-magnetic because the head cylinder is connected to the parts that house the flywheel, and thus, to not cause any chance of interfering magnetic fields the part has to be non-magnetic so the flywheel can easily rotate and create the starter spark. Global factor concerning aluminum is that it is widely available in most geographical locations. Societal factor of aluminum is that the pollution generated from the creation of aluminum that can be detrimental to ones health. An environment factor concerning aluminum would be that it involves mining and the depletion of the earth of it’s natural resources. Another environmental factor would be that the production of aluminum is detrimental to the environment. An economic factor concerning aluminum is that it is very cheap to manufacture; modern mining, melting, etc. are fairly cheap and efficient processes. The component has no aesthetic properties. The component does not have an aesthetic purpose because the consumer is not supposed to see it. The component is grey because it is metal and no one is meant to see it so it does not have to look flashy. There is no surface finish on the product minus the combustion chamber that is lined with excess carbon released from the combustion process. The finishes are functional because they are a result of the product's actual function; the carbon given off during combustion gives the combustion chamber a black finish.

Manufacturing Methods

The part was die cast because there are draft angles and parting lines. Material choice did not impact this selection because aluminum can be easily die cast or easily manufacturing using other methods. The shape is moderately complex which had no impact on the manufacturing choice; the part being medium in size had an impact on the selection because die cast is easy for small to medium parts produced on a large scale. An economic factor of die casting is that die casting is fairly reasonable for mass produced parts, the only high cost is the initial capital cost to make the die. A global factor is that die casting is can be performed globally.

Component Complexity

The component is moderately complex. The component performs multiple functions, and has some interesting features due to the functions it performs. The components function is the main impact of complexity here. The function makes the shape moderately complex because of the semi sphere indent on the bottom used for the combustion process, and the spark plug casing that gives the fuel the energy to run. The geometry of the part is fairly basic and simple, there is not jutting out, or at weird angles. The material choice is fairly common so material selection does not impact complexity. The aesthetics of the part do not play a role in the complexity because there are no aesthetic features because the consumer is not supposed to see the part. The interaction is semi complex because it interacts with the combustion chamber and then also interacts with the spark plug.

Piston Assembly

Piston Assembly
Figure 49: The Piston Assembly.
Component Function

The piston moves up and down to convert the chemical energy from the combustion chamber to mechanical energy. The piston does not serve any other function, its only purpose is to convert energy from one form to another through the expanding of the combustion chamber. The component is associated with energy flow; it takes one form of energy and converts it to another form. The component functions in an isolated environment inside the snow blower; the component heats up due to friction, the heat from the combustion chamber and the conversion of energy, but the outside air does not have contact with the part.

Component Form

The piston is a three dimensional cylinder with the top cut off. The component has two holes on each side of the main shaft that have a bar that runs through them that connects the piston the crank shaft. The piston is symmetrical. The component has a diameter of 2.5 inches, and a height of 2 inches. The component’s shape is coupled with its function because the piston has to be round so it can move and fit in the piston chamber at a constant rate. It is round because being round decreases surface area and allows the piston to move up and down smoothly without any barriers in design. It roughly weighs less than a pound. The component is made of steel because it is magnetic. The manufacturing decisions that went into making it were that it needs to be strong because it needs to pump really fast, it needs to be able to withstand the heat of combustion, and it has to be able to be produced within certain tolerances. A global factor concerning steel is that it is widely available in most geographical locations. A global factor is that the laws for steel production regulation concerning air pollution and emissions vary from region to region. The laws concerning emissions specific to the production of steel in the United States is a societal factor because it pertains to the health and environmental concerns caused by these emissions. Another societal as well as an environmental factor of steel is the pollution generated from the creation of steel which can be detrimental to ones health and to the surrounding environment and ecosystems. Another environment factor concerning steel would be that it is made from iron which involves mining and the depletion of the earth of its natural resources. An economic factor concerning steel is that it is very cheap to manufacture; modern mining and melting are fairly cheap and efficient processes. The metal also has to be able to have a relatively smooth surface finish so that it creates little friction when it goes up and down within the cylinder. The component has no aesthetic purpose because the component is not meant to be viewed by the consumer. The component has no aesthetic properties because it is not viewed by the consumer. The component is grey because it is metal and does not need to be colored because it is not seen by the consumer. The surface finish on the piston smooth with very slight ridges due to the turning manufacturing process. This is for functional reasons, the part has to be smooth, but the ridges are due to how it is manufactured.

Manufacturing Methods

The component is turned so it could be perfectly symmetrical. It appears to be turned because there are slight ridges along the main cylinder and because it is perfectly round. Material choice has some impact on turning the product because some products cannot be turned. Shape did impact the manufacturing selection because the part needed to be turned to ensure that the piston is perfectly round and symmetrical. A economic factor of turning is that turning is not expensive. Global factor is that turning can be done globally.

Component Complexity

The part is fairly simple. It is basically a hollow cylinder with only one function. The function of the component impacts complexity because the part has to be smooth and cylindrical, it has to be simple to ensure that it is symmetrical and perfectly balanced to ensure that it works with efficiency. Geometry makes this part simple because it is a simple shape in order to ensure that the component functions properly. The material choice makes the component simple because steel is a fairly common material. Since there are no aesthetic properties, appearance has no impact on complexity. The manufacturing method selected does not make the part complex because it ensures that the part is symmetrical. The interaction is semi complex because it involves the interaction between the crankshaft and the combustion chamber.

Solid Modeled Assembly

The three components of the chute were chosen to be modeled because they are essential to the use of the snowblower. Without them the snow would not be redirected and could not be cleared from the desired area. There are also design revisions that pertain to the chute in order to improve the snowblower.


Chute Handle
Figure 50: Chute Handle.


Chute Discharge
Figure 51: Chute Discharge.


Chute Deflector
Figure 52: Chute Deflector.


Exploded View of Chute Subsystem
Figure 53: Exploded View of Chute Subsystem.


Chute Assembly
Figure 54: Chute Assembly.


Click this link for Video 1: A video of the chute assembly.

The parts were modeled using Autodesk Inventor 2010. This program was used because it is a user friendly 3D modeling program. It has the ability to create assembly files and exploded views of the components and can create animations. Along with this, one of our group members has experience with the program.

Engineering Analysis

In choosing how large of a fuel tank to include with the snowblower, an engineer might use analysis to set a goal of how many average sized driveways one can clear on a single tank of gas.
Some design implications of an optimum tank size include how large a cavity there is inside of the casing for a fuel tank which provides a maximum volume, as well as what an optimal size for the snow blowers market segment is. A fuel tank that is too large may lead to wasted fuel at the end of the snowblowing season and a fuel tank that is too small will not allow the consumer to effectively clear their driveway without refueling.

Problem Statement

Determine how many times one can snow blow an average sized driveway starting with a full tank of gas when the snowblower is running at maximum power output.

Diagrams

Gas Tank and Motor
Figure 55: Model of Gas Tank and Motor.
Typical Driveway
Figure 56: Diagram of Typical Driveway.

Statement of Assumptions

  • Assume that the fuel tank starts at full volume.
  • Assume that the maximum power output of the engine is 4 horsepower.
  • Assume the engine is running at full capacity all the time.
  • Neglect the volume of fuel in the fuel tank lines.
  • Assume the fuel has a 50:1 gasoline to oil ratio.
  • Assume the oil content plays no part in the combustion process.
  • Assume the engine is 33% efficient.
  • Assume 1 US Gallon of 87-octane gasoline contains 114,000 BTU.
  • Assume the gas tank has a volume of 1 quart.
  • Assume 1 horsepower equals 42.41666 BTU/min.
  • Assume the average driveway is 20 feet wide by 30 feet long.
  • Assume the average driveway is rectangular.
  • Assume the person follows the path outlined in the above picture.
  • Assume the snowblower is moved at a constant velocity of 1 mph.
  • Assume the clearing width of the snowblower is 20 inches.
  • Assume the time needed to turn the snowblower around and adjust the chute takes 30 seconds.

Equations

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Design Revisions

Chute Redesign

The chute will be redesigned so one does not have to physically move from behind the snow blower, up to the chute assembly, to change the angle of snow projection. The current handle on the base of the chute, as seen in the computer aided design in figures 50 through 54 and Video 1, will be removed, and in its place will be an internal system of cables and pulleys that would span from the chute assembly to a joystick located on the user interface panel.

This design alteration will directly impact the people using the machine, thus making it a societal concern. With the current set up comprising of a short handle used to rotate the chute, the consumer is essentially forced to leave his/her position behind the snow blower to manually rotate the chute every time the direction of snow projection needs to be changed. This particular revision will be advantageous in the areas of safety and time. The consumer would now be able to remain in the safe confine behind the handle assembly at all times. If the person had to keep changing positions, as in the current set up, there would be many opportunities for them to slip and hurt themselves. During the process of their fall, there is a slight chance that a body part could wind up in the path of the rapidly rotating blades. Not only would this revision improve the safety of the overall snow blowing process, but it would also reduce the time taken to complete the job. Instead of making multiple trips from behind the snow blower to the chute handle, one can quickly change the direction of snow flow right from the handle assembly. The overall price change in cost for this revision would be minimal and certainly worth it. The chute’s handle would no longer have to be manufactured and in its place would be two smaller levers atop of the handle, pulleys, and cable.

Uniform Bolt and Screw Size

The use of a uniform size bolt and screw throughout the entire system is another revision we would make. The current system has quite a wide variety of fastener sizes, and shapes, making disassembly and maintenance a hassle.

Throughout the snow blower, there are metric bolt and screw heads that range from sizes 8 mm to 14 mm, as well as a few other very small fasteners. It would be highly beneficial for the consumer, as well as the company, if there was a smaller range of fastener sizes. This design revision would have a direct effect on both economic and societal concerns. Toro would be able to manufacture or purchase a smaller variety of fasteners, which would certainly cut down cost. Also, the consumer who could potentially be disassembling or simply performing routine maintenance on the machine will only have to use a small number of socket/wrench sizes. The target audience for the snowblower will certainly not always be advanced mechanics who can pin point the size of a fastener just by looking at it. Thus, reducing the range of fastener sizes will also reduce stress and time for the user. If there were only two different core sizes of fastener heads, the time taken to figure out the corresponding socket size would be very minimal. Overall, this change to the system will enhance serviceability and lower costs.

Eliminating Rust

Another suggested revision concerns replacing a number of parts that are very prone to rusting and replacing them with identical parts made from a different material that is less likely to rust. This could also include applying a quality rust-proof coating to protect metals such as steel against rusting.

As of now, the majority of the parts making up the snow blower are made out of steel. Steel, being chiefly composed of iron, is highly prone to rusting, which will eventually cause defective parts. The environment plays a significant role in the process of electing particular materials to utilize throughout the snow blower. The climate in which a snow blower is used is obviously cold and wet. After use, the machine is, at best, stored in shelter where melting snow coats many components until it eventually self-dries. To add to the oxidation process that will cause the rusting of iron based parts, many drive ways will also have had salt applied to them at some point to melt away ice. Some smaller parts that do not experience excessive force or torsion, therefore do not have to be as durable as steel/iron, could be replaced with aluminum. The components that have to be durable, especially in very cold weather, can be covered with a highly rust-resistant coating. Though this will possibly increase the cost of production, the snow blower’s extended life cycle will be worth the minimal economic loss. This improvement could slightly increase the initial investment for the consumer, but such improvement in quality would be well worth the extra money. The company could also decide to keep the cost the same, while their reputation would benefit from the happiness of the consumer in the context of both price and quality.

Better Wheels

Another suggested revision would be replacing current wheels with enhanced, rough terrain wheels that have increased tire size and tread depth.

The environment in which a snow blower is used can become very harsh in terms of depth of snow or severity of ice. The means of transporting this machine from its place of storage, to the outdoors, and back into its original position are the wheels. The current set of wheels are very small, both width and height wise, and have very little tread depth. These wheel’s characteristics do not provide the consumer with an effective, easy way of moving this machine to where it needs to go. The design of the wheels needs to be revised so that they are larger, both width and height wise, and have an aggressive terrain tread. It is known that the snow blower claws its way forward by means of the blades grabbing onto the snow. However, with the said revisions, maneuvering the machine from its place of storage to where the actual job needs to be performed will be a much easier task for the consumer. Also, turning the machine to change the direction of travel would be a much more enjoyably task. Finally, if there is not enough depth or density to the snow that is being removed, the blades will not have a lot to grab onto to provide the machine with forward motion. This is where the revised wheels will also aid the consumer by making it easier to turn or simply move forward. There will be an economic concern, as the current wheels are most likely very cheap, based on their size and simplicity. Although, this revision will provide the consumer with a much better handling machine that is able to successfully operate in harsh winter conditions. The overall cost of manufacturing better wheels will be completely worth it as the company’s reputation will be enhanced.