Group 35 - Leaf Blower Engine
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===Product Reassembly Plan=== | ===Product Reassembly Plan=== | ||
Revision as of 17:33, 8 December 2009
Contents |
Introduction
Group Roles
- Gennady Agapov: Gantt Chart, Wiki Page Editor
- Seth Hughes: Pictures and Charts, Solid Modeling
- Zelu Xu: Wiki Page Editor
- Jeff Scipioni: Assembly/Disassembly, Wiki Page Editor
- Chandrishka J. De Silva: Pictures and Charts Wiki Page Editor
Work Proposal
Our plan for reverse engineering will start with disassembly of the engine. We will first remove all exterior components. Once the engine is broken down to its main components, we can begin complete disassembly. The tools required for this are flathead and Phillips head screw drivers of various sizes, metric sockets and wrench set, needle nose pliers, hex keys, and allen keys, all of various sizes. The whole process of disassembly should not take longer than one to two hours, as it is a small engine. The group has members that are capable of the process, however, the ones that aren’t, will be able to learn as we go. We don’t expect to encounter any shortcomings during the disassembly
Management Proposal
Our group plans to manage our work by meeting regularly, and working consistently. Our planned meeting times thus far are Tuesday at 3:30 pm, Thursday at 4:30 pm, and Wednesdays after 5 pm. All meetings will be held in the dissection lab or the library. Our plan to meet the project requirements are discussed in the Gantt chart provided. The members in charge of assembly and disassembly are Jeff Scipioni and Chandrishka J De Silva. Our group member in charge of the Wikipedia page will be Seth Hughes, and the group leaders in charge of time management and overview are Gennady Agapov and Zelu Xu.
Inital Product Assessment
Causes for Corrective Action
Essentially our work proposal and management proposals have gone according to the plan. All of our group members have contributed evenly, including meeting regularly and working in a timely fashion. The work is divided evenly according to each group members’ strengths. As far as our disassembly process as described in our work proposal, we were mostly accurate. Some of the tools outlined were not required. ” The tools required for this are flathead and Phillips head screw drivers of various sizes, metric sockets and wrench set, needle nose pliers, hex (torx) keys, and allen keys, all of various sizes.” What we used were the metric sockets and wrench set, need nose pliers and torx wrenches, and Phillips head screw driver. We didn’t use the allen keys, or the flat head screwdriver. The time we proposed it would require was a slightly over estimated. “The whole process of disassembly should not take longer than one to two hours, as it is a small engine.” The process was only around 45 minutes, for disassembly and disassembly.
Product Dissection Plan
| System | Parts | Disassembly Description (Est. Time) | Difficulty | Tools Used | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Exhaust System | - Muffler Cover/Body,- Internal Packing,- Exhaust Gasket | The exhaust is held on with two t25 torx bolts. The exhaust system itself was missing the internal packing used for sound muffling. (3 min) | 1 | T25 torx | ||||||
| Gas Tank | Tank and the Cap | Held on by crank case cover (4 short T25 torx bolts) | 1 | T25 torx | ||||||
| Air Filter Assembly | Cover/Body,Air Filter,Gasket | The air filter is directly mounted to the carburetor with two 10mm bolts. No air filter material found inside the casing. (5 min) | 1 | 10mm wrench | ||||||
| Carburetor System | Float Bowl,Primer,Main Body,Spacer | The float bowl of the carburetor is held on with two Phillips head screws, as is the primer bulb. The spacer between the carburetor and the cylinder, and the carburetor itself is held on with two T25 torx bolts. (15 min) | 1 | Phillips head screw driver | ||||||
| Flywheel Cover | Body Cover,Rope,Spring | There was no pull start assembly/flywheel cover present. If it were present, it would be held on with 4 T25 torx bolts that were provided. (5 min) | 1 | T25 torx | ||||||
| Ignition System | Spark Plug,Spark Plug Wire,Solenoid | One T25 torx bolt held the magnetic solenoid to the crank. (3 min) | 1 | T25 torx | ||||||
| Flywheel Assembly | Flywheel,Bushing,Key | The flywheel is held by a large aluminum nut that is easy to unscrew, however a torque wrench is required to tight it back up. The bushing slides of the flywheel with ease.
(5 min) |
1,1,1,5 | |||||||
| Cylinder | The top cylinder block is only held by 3 long screws which must be torque wrenched during assembly process.(5 min) | 1 | T25 torx | |||||||
| Base Gasket | 1 | |||||||||
| Crank Shaft | 1 | |||||||||
| Piston Assembly | Piston,Piston Ring,Connecting Rod,Wrist Pin | To remove the connecting rod from the piston, snap ring pliers are needed, which are not provided in the dissection lab. Also, the piston ring was absent. (10 min) | 1,5,3,5,5 | |||||||
| Block Assembly | Main Block,Open Bearing,Sealed Bearing | We left the crank in the crank case; we needed a small press to remove the bearings to retrieve the crank assembly, without rendering the bearings useless. | 1,1,5,5 |
| Part Name | Quantity | Material | Function | Manufacturing Process | Model/Part Number | Applied Force | Complexity | Functional or Cosmetic | Image | |
|---|---|---|---|---|---|---|---|---|---|---|
| Exhaust | 1 | Aluminum | exit point for the burnt gases from the engine and also lower the sound output | Metal Stamping | not provided | n/a | 2 | Functional |  | |
| Gas tank with cap | 1 | Plastic | Holds gasoline and delivers it to the carburetor | Injection Molding | not provided | n/a | 2 | Functional |  | |
| Air filter | 1 | Plastic | Provide clean air to the carburetor | Die Casting | not provided | n/a | 1 | Functional |  | |
| Carburetor | 1 | Aluminum | Supply fuel and air mixture to the engine | Investment Casting | not provided | n/a | 5 | Functional |  | |
| Fly wheel | 1 | Aluminum | Produce electricity for the engine | Die Casting | not provided | centripetal | 3 | Functional |  |
|
| Ignition system | 1 | Combination of Metal and Plastic | Convert the electricity generated from the fly wheel to a spark for the spark plug. | assembled by hand | not provided | n/a | 5 | Functional |  | |
| Cylinder | 1 | Aluminum | The cylinder is a place for the gases to combust, from the pressure provided by the piston and the spark provided by the ignition system. | Die Casting | 06825 | compressive | 3 | Functional |  | |
| Gaskets | 1 | Paper | Provide sealing for different components. There are gaskets between the cylinder and block, the carburetor and the cylinder, and exhaust | stamped | not provided | n/a | 1 | Functional |  | |
| Piston | 1 | Aluminum | Reciprocate up and down inside the cylinder providing pressure for the combustion process | Die Casting | not provided | compressive | 3 | Functional |  | |
| Connecting rod | 1 | Aluminum | Connects the piston to the crank and provides the up and down motion | Die Casting | not provided | tensil | 3 | Functional |  | |
| Block | 1 | Aluminum | Houses the main engine components. All of the other components either bolt to or go inside the block | Die Casting | not provided | compressive | 4 | Functional |  | |
| Bearings | 2 | Steel | Provide less resistance in the spinning shafts of the crank | not provided | centripetal | 3 | Functional |  | ||
| Bolts | 25 | Steel | Attach different components of the engine to one another | Die Casting | not provided | shear and comopressive | 2 | Functional |  |
Design Revisions
1. A slight increase in engine displacement would be increase power, resulting in a more powerful leaf blower. With more blowing power, the user will be more satisfied in the product because of it's increased efficiency.
2. A higher quality exhaust would not only be a good improvement for the user, but any one in the vicinity of the leaf blower. The current exhaust system is a simple aluminum shell, that is supposed to have a packing material inside, however ours is missing. To replace this with a tubed exhaust with a silencer would greatly decrease the sound output of the motor
3. There is a plastic spacer between the carburetor and the cylinder. It could easily be eliminated by making a slight design revision in the carburetor. Doing this would decrease production costs because the part would no longer be necessary.
Engineering Analysis
Problem Statement
In a leaf blower engine the piston should support a maximum temperature, compression and a maximum pressure. If the piston ring is broken in some way the gas volume will change and a significant compression loss will be there. Determining that compression loss.
Diagram:
The combustion chamber is where our initial volume and clearance volume is calculated. Our engine is a Homelite two stroke with a displacement of 26 cc which can be converted to .026 liters. Clearance volume is when the piston is at the top of the stroke.
Assumptions
- The initial volume to be V_i=400CMF. (cubic feet per minute) http://www.cpohomelite.com/products/zr08550.html
- The leaf blower engine is 26cc.
- If there is a compression lose, the clearance volume would be higher than the usual.
- Calculations are based only according to the above diagram, which is considering only the piston system.
- Compression ration 10:1 = V_i: V_C
Governing Equations:
C_r=((V_i+V_C ))/V_C
C_r=(((π/4×d×l)+V_C ))/V_C
- C_r= compression ratio
- V_i= initial volume
- V_C= clearance volume
- d= diameter of the cylinder
- l= length of the piston
Calculations
10=((400CMF+V_C ))/V_C
V_C=44.44 CMF
| V_i | V_c | C_r | |||
|---|---|---|---|---|---|
| 400 | 45 | 9.89 | |||
| 400 | 50 | 9.00 | |||
| 400 | 60 | 7.67 | |||
| 400 | 70 | 6.71 | |||
| 400 | 80 | 6.00 | |||
| 400 | 90 | 5.44 | |||
| 400 | 100 | 5.00 |
| System | Parts | Reassembly Description (Est. Time) | Difficulty | Tools Used | Image |
|---|---|---|---|---|---|
| Block Assembly | Main Block,Open Bearing,Sealed Bearing | Begin with main block and insert the base gasket onto the top being sure to align the holes. | 1,5,5 | no assembly required |  |
| Crank Shaft | No reassembly required. The crank shaft is already installed inside the main block. | 1 | already assembled |  | |
| Piston Assembly | Piston,Piston Ring,Connecting Rod,Wrist Pin | Place the connecting rod with the piston attached onto the crank shaft. Do this by aligning the hole on the lower end of the connecting rod onto the round crank shaft. | 1,5,3,5 | already assembled |  |
| Cylinder | Place the cylinder over the piston and bolt to the main block and base gasket using the 3 long bolts which must be torque wrenched during assembly process.(5 min) | 1 | T25 Torx |  | |
| Carburetor System | Float Bowl,Primer,Main Body,Spacer | The carburetor was not completely disassembled. The float bowl of the carburetor is held on with two Phillips head screws, as is the primer bulb. Include the black spacer between the cylinder and the carburetor which is held on with two T25 torx bolts. Also place the gasket between the carburetor itself and the cylinder. | 1 | T25 Torx, Phillips head screw driver |  |
| Flywheel Assembly | Flywheel,Bushing,Key | Bolt the flywheel to the crank shaft using an aluminum bushel and the nut provided. The flywheel must be aligned with the key way on the crank shaft as shown in the image. | 1,1,5 | 10mm wrench |  |
| Ignition System | Spark Plug,Spark Plug Wire,Solenoid | Screw a single T25 torx bolt which holds the magnetic solenoid to the cylinder. Press the spark plug cap onto the spark plug. | 1 | T25 Torx |  |
| Flywheel Cover | Body Cover,Rope,Spring | There was no pull start assembly/flywheel cover present. If it were present, it would be held on with 4 T25 torx bolts that were provided. | 1 | T25 torx | |
| Air Filter Assembly | Cover/Body,Air Filter,Gasket | The air filter is directly mounted to the carburetor with two 10mm bolts. No air filter material found inside the casing. Include the gasket between the aif filter assembly and the carburetor. | 1 | 10mm wrench |  |
| Gas Tank | Tank and the Cap | Use 4 T25 torx bolts to hold the gas tank to the block. Also make sure that the small, black, rubber stoppers are intact to the gas tank to hold it more securely in place. | 1 | T25 Torx | |
| Exhaust System | - Muffler Cover/Body,- Internal Packing,- Exhaust Gasket | The exhaust is bolted to the cylinder using two T25 Torx bolts. The exhaust system itself was missing the internal packing used for sound dampening. | 1 | T25 Torx | |
