Group 12 - Leaf Blower
Contents |
Executive Summary
The objective project was for our group, twelve, to look into the assembly, function, manufacturing, and materials of a leafblower. The leafblower is a common device used by lawn care companies and some household owners. We analyzed the product, disassembeled it while taking careful notes and then reassembled the leafblower. We took pictures for the disection processes, recorded the level of difficulty for each step and analyzed each part of the product with great detail. The group worked well together as a team to complete this goal.
GATE 1: REQUEST FOR PROPOSAL
The link below is a detailed description of our request for proposal that includes the following:
Purpose
Work Proposal
Time Management
Group Assesment
Management Proposal
Inititial Product Assesment
Functionality and Complexity
Alternatives
GATE 2: PRELIMINARY DESIGN REVIEW
The link below is a detailed description of our preliminary design review that includes the following:
Causes for Corrective Action
Product Dissection Plan
GATE 3: COORDINATION REVIEW
Introduction
This is the second major project review. To complete this stage we analyzed the product and its assorted components. Design revisions, a detailed chart of components, solid modeling and eningeering analysis are given below.
Causes for Corrective Action
As group twelve progresses in this disection process, we need to evalute our progress. There have been minimal problems with the group and tasks assigned. One problem is a malfunction with GICL, preventing us from uploading images to enrich our component summary. A solution to this is to explain the lack of images and upload them when able. Otherwise, our group has been communicating very well, and working together as a strong team.
Design Revisions
1. Adding a strap to the base of the handle and to the beginning of the nozzle. This would reduce the strain on the hands of the user by deferring part of the weight of the user’s shoulder. This would be an ergonomic change. Consequently this would also increase the price of the product. This product is targeted towards lawn care business who would frequently use the product. The product is most commonly used by young to middle aged people. Extended periods of use could cause strain on the uses hands. The strap revision would accommodate this problem. With this change in orientation would cause the exhaust fan to rest on the user’s body. This problem would cause discomfort.
2. To cope with the problem caused by the strap, an additional revision to the exhaust outlet would need to be made. The exhaust fan currently blows at the user, our change would redirect the exhaust heat to the rear of the leaf blower, away from the user. This change would increase the cost, but the benefit of this ergonomic change would outweigh price increase.
3. After long term use, the current design of the handle can create unwanted pressure points on the user’s hand. The reshaping of the handle into the contour of a human hand will disperse the pressure across a larger area. This change would benefit users who regularly use the leaf blower for extended periods of time. This modification could be done with little to no increase in the price.
4. Moving the blower nozzle to the top of the body of the leaf blower and changing the angle of the nozzle from horizontal to a downward angle, would allow someone to operate the leaf blower without tilting it downward. This change would require the redesigning of the leaf blower’s body to accommodate for redirection of the airflow. The redesigning process would have a large frontal cost but a low change in price thereafter.
5. To make the leaf blower lighter, the engine compartment could be reduced in size. This would increase the heat of the engine, because the main method of cooling is convection. To counteract the heating, a part or all of the air could be sent through the engine compartment to the nozzle. This would require the engine compartment to be air tight. However, this would solve the problem of the exhaust by making the nozzle double as the exhaust exit.
6. To increase the exit velocity, the area of the exiting end of the nozzle could be reduced. The ideal shape is still a horizontal ellipse, because the goal is still to move as many leaves at once. A small circle would have the most power output but would only be able to move a small amount of leaves a small distance because of the air resistance on of a leaf. A slightly thinner ellipse would increase the exit velocity while maintaining a large area of effect. This change would have a low increase in price of the product.
Solid Model Assembly
The CAD package chosen to make the model was Autodesk Inventor. This software was chosen because the designer of the group, James, had prior experience using it and had access to the program. It was the easiest to use based on these reasons.
The main parts modeled were the carburetor, the fan, and block engine. These components were selected because these were the parts we into the most depth about. The carburetor shows the on/off switch, the choke, and primer. The on/off switch and choke move up and down in the model to show their primary functions. The valves open and close according to the switch’s position. Next is the fan and block engine. They are assembled together and move in order to display their functions. The magneto spins as the rip chord is pulled and it sparks and starts the fan. The fan spins as it would when the leaf blower is running. Due to the time constraint, the piece of metal the magneto hits was left out.
Below is a 3D model of the carburetor.
Due to technical problems with GICL, not all of the solid modeling was able to be uploaded directly to the Wikipedia page. We also used an external web page, youtube.
Click for a solid modeling of the seven blade fan: [1]
Component Summary
Due to technical problems with GICL, pictures the group has taken of each individual component can not be uploaded for clarification.
For aesthetic purposes of the chart, materials is abbreviated to mtrl.
The fuctionality is abbreviated in either F or A. "F" means the part is purely functional. "A" means the part is added for asthetic value. An "F" and an "A" implies the part is designed with both functionality and astehtic qualities considered.
The complexity component is in comparison to other parts, and on a scale of 1 to 10. Ten being the most complex and one being the least complex. A one represents a basic part with little to no complexities, is easy to produce, or has one simple function. A ten represents a part with several subparts that we were not able to remove, is difficult to produce, or has a complex function.
| Part | Quantity | Mtrl | Manuf. Proc. | Function | Mtrl Reason | Mtrl Affects | Shape Affects | Manuf. Reason | Shape reason | Funct. | Complexity & Forces Applied |
|---|---|---|---|---|---|---|---|---|---|---|---|
| ENGINGE BLOCK File:Engine3.jpg |
1 | Aluminum | Cast | Serves as enclosure for piston, crankshaft, and connecting rod | Durable under high heat and vibration, lightweight | Forging or Casting | Difficult to forge: grooves and shapes involved; small part. Casting: molten metal is poured into a mold; accommodates for complexities | Simplicity with respect to forging and inexpensive and easy to mass produce | Maximize surface area, therefore maximzizing heat dissipation | F | 10 Torque from Screws Explosive force from combustion |
| CYLINDER HEAD | 1 | Aluminum | Cast | Holds spark plug. Seals combustion chamber. | Aluminum is durable under high heat and vibration | Forging or Casting | Difficult to forge: grooves and shapes involved; small part. Casting: molten metal is poured into a mold; accommodates for complexities | Simplicity with respect to forging and inexpensive | The inside of the cylinder head has a recessed circular area, which serves as the top of the combustion chamber. This section must be smooth in order to guarantee an even explosion inside the combustion chamber. | F | 9 |
| CRANK SHAFT | 1 | Steel | Cast | Converts reciprocating motion of piston into rotational motion of driveshaft. | Steel is extremely durable under high heat and vibration. | Forging or Casting | Difficult to forge: grooves and shapes involved; small part. Casting: molten metal is poured into a mold; accommodates for complexities | Simplicity with respect to forging and inexpensive | Well balanced, in order to minimize vibration, and increase longevity. | F | 10 |
| CRANK SHAFT BEARINGS | 1 | Steel | Cast | Allows crankshaft to rotate with limited friction. | Steel is extremely durable under high heat and vibration. | Forging or Casting | Casting is easier. Both would work. | Simplicity with respect to forging and inexpensive | Designed to reduce friction by sandwiching several layers of metal between the crankshaft and the engine block. | F | 5 |
| PISTON | 1 | Aluminum | Cast | moves up and down the cylinder, compressing gasses and creating vacuum | Steel is extremely durable under high heat and vibration. | Forging or Casting | Shape would not rule out the use of forging, though this is only used in applications with extreme forces acting on the piston. | Simplicity with respect to forging and inexpensive | Designed to be perfectly round, and match the inside of the cylinder. | F | 10 |
| PISTON RING | 2 | Aluminum | Cast | Seals space between piston and cylinder wall. Allow for compression to be built on compression stroke. | Aluminum is extremely durable under high heat and vibration | Casting would be the only reasonable option | Difficult to forge, because of the delicacy of it. Casting would be much easier and more practical. | Simplicity with respect to forging, its ability to produce delicate parts, as well as for being relatively inexpensive. | Designed to be the exact same circular shape as the cylinder wall, allowing for a perfect seal between the two. | F | 3 |
| CONNECTING ROD BEARING | 2 | Aluminum | Cast | Reduces vibration between the connecting rod and piston, as well as between the connecting rod and crankshaft | Aluminum is extremely durable under high heat and vibration | Forging or Casting | Smaller sub-components are first produced, then later assembled. Because of this, forging is reasonable, though casting is much less expensive. | Simplicity with respect to forging, its ability to produce delicate parts, as well as for being relatively inexpensive. | Designed with rollers inside the bearings, in order to reduce the friction between parts. | F | 6 |
| PULL STARTER | 1 | Aluminum Nylon Plastic |
Cast | Allows user to turn over, and start engine | Aluminum: resistance to wear, and high strength. Nylon: wound into lengths of cord. Plastic: where lightweight parts were necessary, and the strength could be sacrificed. | Forging or Casting | Forging would be unnecessary. Casting would likely be chosen for the method of production. | Casting was chosen because of its simplicity with respect to forging, as well as for being relatively inexpensive. | Designed to be circular, in order to fit around the crankshaft of the engine. | F | 7 |
| Part | Quantity | Mtrl | Manuf. Proc. | Function | Mtrl Reason | Mtrl Affects | Shape Affects | Manuf. Reason | Shape reason | Funct. | Complexity Forces Applied |
|---|---|---|---|---|---|---|---|---|---|---|---|
| SEVEN BLADE FAN | 1 | Plastic | Injection Molded | Moves surrounding air into leaf blower, and pushes it out of the nozzle | Plastic is lightweight, and impact resistant | Injection Molding | Due to complexity in shape of this design, injection molding, similar to the casting of metal parts, was chosen | Versatility, and ability to create complex shapes | Designed to push the most air possible. Through research and development, designers were able to conclude that this seven blade fan found on the leaf blower met these standards. | F | 3 |
| WASHER | 1 | Grade Five Steel | Hardened Grade Five Steel | Holds the fan onto the drive shaft | Durablilty of steel | Cast | Due to the grade, cast is sufficient | Relative ease of manufacture, and steel was later hardened to ensure added strength. | Designedto fit around the driveshaft, in order to hold the fan securely | F | 2 |
| 9/1" NUT | 1 | Grade Five Steel | Hardened Grade Five Steel | Holds the fan onto the drive shaft | Durablilty of steel | Cast | Due to the grade, cast is sufficient | Relative ease of manufacture, and steel was later hardened to ensure added strength. | Designed to take up as little space possible, in order to reduce bulk | F | 2 |
| FAN GUARD | 1 | Plastic | Injection Molded | Keeps foreign objects out of fan chamber. Also protects operator from injury. | plastic is lightweight, and impact resistant | Injection molding | Due to complexity in shape of this design, injection molding, similar to the casting of metal parts, was chosen | Versatility, and ability to create complex shapes | Designed to allow the maximum amount of air into the fan chamber, while keeping the maximum amount of foreign objects out. | F A |
8 |
| Part | Quantity | Mtrl | Manuf. Proc. | Function | Mtrl Reason | Mtrl Affects | Shape Affects | Manuf. Reason | Shape reason | Funct. | Complexity & Forces Applied |
|---|---|---|---|---|---|---|---|---|---|---|---|
| COIL | 1 | Plastic Ceramic Aluminum |
Injection Molded Cast |
Produces spark for spark plugs. | plastic is lightweight, and impact resistant | Injection molding Casting |
Due to the complexity in shape of this design, injection molding was chosen for the plastic pieces. casting was chosen for the aluminum parts. | Versatility, and ability to create complex shapes | Designed to allow the maximum amount of air into the fan chamber, while keeping the maximum amount of foreign objects out. | F | 4 |
| SPARK PLUG CAP | 1 | Plastic Aluminum |
Cast Injection Molded |
Connects spark plug to spark plug wire. | Plastic is a durable insulator, while aluminum is a durable conductor. | Casting Injection Molding |
Shape was much less relevant than other factors such as cost | Versatility, and relatively low cost of production. | Designed to fit the spark plug tightly | F A |
3 |
| SPARK PLUG WIRE | 1 | Rubber Copper |
Small strands of extruded copper are wound to form a wire | Connects spark plug cap to coil. | Rubber is a durable insulator, while copper is an excellent conductor. | Small strands of extruded copper are wound to form a wire | Copper must be drawn into lengths. | Multiple strands used to ensure maximum efficiency. | Designed so that it was thick enough to be well protected and efficient, but thin enough to not get in the way of other components. | F A |
5 |
| FLYWHEEL MAGNET | 1 | Permanent Magnet | Heating up magnet and then hammering it in the direction of the north/south pole | Creates charge used to power spark plug. | Magnet is required for the forces of attraction | Heating up magnet and then hammering it in the direction of the north/south pole | Very small, so hammering must be done with specialized machines. | Method used has been around for centuries, and is very affordable. | Designed to minimize mass, while maximizing magnetic force. | F | 6 |
| Part | Quantity | Mtrl | Manuf. Proc. | Function | Mtrl Reason | Mtrl Affects | Shape Affects | Manuf. Reason | Shape reason | Funct. | Complexity & Forces Applied |
|---|---|---|---|---|---|---|---|---|---|---|---|
| CARBUREUTOR | 1 | Aluminum | Cast | Supplies engine with fuel and air | aluminum is very durable under heat and vibration | Casting | Casting | Versatility, and relatively low cost of production | Designed to allow the maximum amount of air into the carburetor, while holding the air filter securely | F | 7 |
| CARBUREUTOR SWITCHES | 2 | Plastic | Injection Molding | Richens carburetor/adjusts engine speed | Plastic is durable yet light | Injection Molding | Injection Molding can create intricate shapes | Versatility, and relatively low cost of production | Designed so that they have minimal weight, but are easy to use | F | 3 |
| AIR FILTER | 1 | Foam | Polymer Injected | Protects foreign objects from entering the carburetor | Foam is porous, which allows air to pass, while trapping dust, and other harmful particles. | Polymer Injection | Polyurethane foam is very versatile, so shape affects manufacturing process very little. | Polyurethane is often generally created through polymer injection. | Designed so that it fit inside the air filter cover. | F | 2 |
| AIR FILTER COVER | 1 | Plastic | Injection Molded | Holds air filter | Lightweight and impact resistant | Injection Molding | Injection Molding | Versitilty and ability to create complex shapes | Designed so that it fit inside the air filter cover. | F A |
3 |
| FUEL TANK | 1 | Plastic | Blow Molded | Holds fuel | Lightweight and impact resistant | Injection Molding Blow Molding |
Because the fuel tank is hollow, blow molding would most efficiently create a bubble shape | Ability to make large hollow containers | Designed so that it holds a maximum amount of fuel, while not being excessively large so that it is impractical for the user to carry it | F A |
5 |
| Part | Quantity | Mtrl | Manuf. Proc. | Function | Mtrl Reason | Mtrl Affects | Shape Affects | Manuf. Reason | Shape reason | Funct. | Complexity & Forces Applied |
|---|---|---|---|---|---|---|---|---|---|---|---|
| MAIN ENGINER ENCLOSER | 1 | Plastic | Injection Molded | Protects engine, and makes overall unit aesthetically pleasing | Lightweight and impact resistant | Injection Molding | Injection Molding | Versatility | Designed to protect the engine well, by being durable, while also looking attractive to buyers. | F A |
5 |
| HANDLE | 1 | Plastic | Injection Molded | Allows user to grip the unit | Lightweight and impact resistant | Injection Molding | Injection Molding | Versatility | Designed to allow the user to have a secure, yet ergonomic hand hold on the unit. | F A |
5 |
| CARBURETUR COVER | 1 | Plastic | Injection Molded | Protects the carburetor | Lightweight and impact resistant | Injection Molding | Injection Molding | Versatility | Designed to be lightweight, yet protective of the carburetor | F A |
5 |
| EXHAUST COVER | 1 | Plastic | Force Molded | Protects the carburetor | Lightweight and impact resistant | Force Molding | Force Molding | Excellent heat resistance | allows the exhaust to cool, and exhaust gasses to escape, while protecting the user from coming in contact with the exhaust. | F A |
5 |
| AIR TUBE | 1 | Plastic | Extrusion Molding | Channels high velocity air from fan to the ground | Lightweight and impact resistant | Extrusion Molding | Extruson Molding | Excellent durability | Designed to allow a maximum volume of air flow through it, while maintaining a high velocity. | F A |
5 |
Engineering Analysis
Problem: Solve the analysis problem defined by my group members. Our problem was our spark plug fouled over time.
Assumptions:
• The magneto is working correctly.
• The circuit is completed when the spark plug is working correctly and allows electron flow.
• The spark plug is fouled to the degree to which it no longer allows electron flow.
• The amount of voltage needed by a spark plug to fire is 5000 Volts up to 10000 Volts.
• The minimum amount of ohms required to fire off a spark plug normally is 10 Ohms. At 0 Ohms the spark plug will not fire.
Governing equations:
V=I*R
Solution:
V = I * R => 5000 V = I * 10 ohm => I = 500 A
V = I * R => 10000 V = I * 10 ohm => I = 1000 A
V = I * R => 5000 V = I * 5 ohm => I = 1000 A
V = I * R => 10000 V = I * 5 ohm => I = 2000 A
V = I * R => 5000 V = I * 1 ohm => I = 5000 A
V = I * R => 10000 V = I * 1 ohm => I = 10000 A
Discussion:
From the calculations, the spark plug requires at most 1000 A to run normally. The spark plug has a varying range of voltages so at times even when the spark plug’s resistance is decaying the spark plug still has a chance to fire normally. However most of the time the lower resistances will have misfires and function abnormally. When the resistance drops to 0 then the spark plug does not have any energy to create a spark. This is not the only way that a spark plug can foul. More commonly, the spark plug can foul by having the gap grow to such a distance that a spark cannot be created, or the spark plug erodes, corrodes, or physically breaks to a point where it can no longer complete the circuit. When the damage is to that degree, electrons can no longer flow and create a spark.
Sources: The assumptions of voltage and Ohms were gathered from the website: http://www.jackssmallengines.com/reading_sparkplugs.cfm
Contact Us
Group 12 (Leader: Michael Ciambella) mjc65@buffalo.edu
