Group 36 Documentation and Analysis

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Sunday May 19 2013 04:04

Introduction

This is the coordination review for Group 36. This gate includes the findings for during dissection. These findings are shown in a component summary, design revisions, solid modeling assembly, and an engineering analysis. The component summary is a list of the parts in the product and information about them. The design revision are ways the group felt the product could be improved. The solid modeling assembly was to give a virtual representation of a subsystem of the product and the engineering analysis is a process that could be taken to test a source of possible failure on the product.

Directory

Home: Group 36 Home Page

Gate 1: Request for Proposal

Gate 2: Preliminary Project Review

Gate 4: Critical Design Review

Component Summary

Component List

L - length of cylindrical section of screw or bolt
D - larger diameter for that part
d - smaller diameter for that part

A magnet was used to determine whether a part was made of aluminum or steel. This is because aluminum is not magnetic, but steel for the most part is. Only some specific steel alloys are not magnetic, but these alloys are not present in this engine.

The component complexity is rated on a scale from 1-5 where 1 is simple and 5 is complex. The rating will be determined by evaluating several factors which include number of parts and how difficult it was to manufacture the process.

Since the components being analyzed here are all parts of an engine the vast majority of them are functional. This is because they will not be seen and it is much more important to have the internal workings of an engine be efficient than to look good. The only part that has any real reason to be cosmetic would be the transmission casing. The clutch cover does have some cosmetic touches such as the sleek shape and it also has the name of the company. The transmission housing as a whole is smooth and sleek, but is still a functional part because it is smooth to reduce drag and to prevent the rider from injuring themselves on it. The housing itself is also meant to be for structural support and protection.

All bolts and screws used were made of steel.

Component: Inner Left Transmission Case

Figure:Clutch

See: Figure:Clutch

Function: It houses transmission, protects it from dirt and debris, and provides support for the axles to keep them in place. It also keeps the engine in place using two metal rods that slide through holes through the cylinder and valve assembly sections.

Material: Aluminum is used for the vast majority of the component. The rods are steel with a copper coating. The rolling element bearings are steel. The spur gear in this casing is made of a hard rubber interior and has a steel outer ring and spurs.

Manufacturing Process: The casing was mold casted. The holes for the screws were drilled after the cast was made. Some of these holes were tapped. The two rods were drawn to the desired diameter and then threaded at the end with a die. The two bearings in the casing were assembled outside then glued into indentations in the case. The gear was machined by drilling and milling.

Model/Part Number: N/A

Miscellaneous Information: One of the indentations fitted for an axel contains a caged radial ball bearing whose components were machined and then assembled to the casing. Another indentation in the casing for an axel has a thrust bearing with cylindrical rollers made and used in a similar way to the ball bearing.

Part Count: 1

Fasteners

2 hexagonal washer bolts L=60 mm D=10 mm d=6 mm
1 hexagonal washer bolt L=48 mm D=10 mm d=6 mm
4 hexagonal washer bolts L=64 mm D=10 mm d=6 mm

Complexity: 2 This component is not very complex. It does not contain many parts and can be easily manufactured.

Component: Inner Right Transmission Case

Figure: Transmission (Front View)

See: Figure: Transmission % Transmission (Front View)

Function: It houses the shafts and gears of the transmission and keeps them in place. It also contains two rods used to hold the cylinder and valve assembly sections in place.

Material: The case is made of aluminum. The rods are steel and are coated in copper.

Manufacturing Process: The casing was mold cast as then the holes were machined into it. Some of these holes were then tapped. The two rods were drawn to the desired diameter and then threaded at the end with a die.

Model/Part Number: N/A

Miscellaneous Information: The transmission, crank shaft, the shaft for power output, magneto shaft, and the centripetal clutch are all held to this section of the transmission housing.

Part Count: 1

Complexity: 4 This part is reasonably complex. Unlike the inner left housing, this section holes drilled through it to support all the shafts. It also has to keep all crank shaft and transmission balanced. It requires more machining after the initial cast.

Component: Transmission

Figure: Transmission

See: Figure: Transmission

(The transmission parts were pressed together they were not completely disassembled and will be counted as a single component)

Function: It is used to transfer the power from the engine to the drive chain.

Material: Steel is the main material making up the gears and axels. There is one spring that is made of copper.

Manufacturing Process: The gears are machined using a variety of processes including drilling for the center hole, milling for the spurs, and broaching for the key ways. The axles are machined to the desired diameter using a lathe. They are also milled to have the splines put on. The spring is machined into the coil shape.

Model/Part Number: N/A

Miscellaneous Information: The transmission assembly also includes copper and steel spacers between some of the gears and there are two steel brackets put in place for support.

Part Count: 10 gears, 3 shafts, 1 spring

Fasteners

2 copper spacers
3 steel spacers
2 brackets

Complexity: 5 This is a very complex component with a lot of moving parts. Each gear must be able to smoothly lock into place and also change which gear they are locked into. Each part also needs to be a precisely machined.

Component: Shifting Mechanism

Figure: Shifting Attachment

Figure: Shifter

See: Figure: Shifting Attachment & Shifter

Function: Used to change what gear the dirt bike is in.

Material: All parts are made of steel. There is a section on the selection lever made of rubber.

Manufacturing Process: These parts were all machined. The sprocket was drilled and milled and the shaft was lathed to the desired diameter. The longer gear select mechanism part was pressed into shape and the cylindrical protrusion was welded on. The rounder part was pressed as well. The select arm was cast molded as two parts then welded together.

Model/Part Number: N/A

Part Count: 1 sprocket, 1 spring, 1 axel, 1 select lever

Fasteners

1 hexagonal full thread tap bolt L=20 mm D=9 mm d= 5 mm

Complexity: 3 Some of the parts for the shifting mechanism are uniquely shaped and therefore need a more intricate machining process. However there are not too many parts to this component, which keeps it from being too complex.

Component: Piston Housing

Figure: Piston Housing

See: Figure: Piston Housing

Function: It is the cylinder that encloses the piston and is the site of combustion.

Material: Aluminum except for the internal cylinder which is made of steel.

Manufacturing Process: The part is mold caste and there are several holes that are drilled. The interior cylinder looks machine finished (ground smooth). One of the holes was tapped.

Model/Part Number: N/A

Miscellaneous Information: The fin-like protrusions appear to be a way to disperse heat from the part.

Part Count: 1

Fasteners

1 hexagonal full thread washer bolt with Phillips slot L=20 mm D=10 mm d=5 mm

Complexity: 2 This is a very simple part because it can be easily manufactured. The only real complexity is because of the need for different materials between the interior cylinder and the housing.

Component: Outer Left Transmission Case (Magneto Cover)

Figure: Magneto Cover

See: Figure: Magneto Cover

Function: To cover and protect the magneto and other components on the left side of the transmission.

'Material: aluminum

Manufacturing Process: mold caste

Model/Part Number: N/A

Miscellaneous Information: N/A

Part Count: 1

Fasteners

1 hexagonal washer bolt L=28mm D=10 mm d= 5 mm
1 hexagonal washer bolt L=35mm D=10 mm d=5 mm

Complexity: 1 This housing requires minimal machining and has no moving parts.

Component: Outer Right Transmission Case (Clutch Cover)

Figure: Clutch Cover & Kick-Start

'See: Figure: Clutch Cover & Kick-Start

Function: To cover and protect the clutch and other components on the right side of the transmission.

Material: aluminum

Manufacturing Process: mold cast

Model/Part Number: N/A

Miscellaneous Information: N/A

Part Count: 1

Fasteners

1 hexagonal washer bolt L=80 mm D=10 mm d=6 mm
2 hexagonal washer bolts L=64 mm D=10 mm d=6 mm
5 hexagonal washer bolts L=40 mm D=10mm d=6 mm

Complexity: 1 Like the magneto cover, the clutch cover can be easily manufactured and contains no moving parts.

Component: Magneto/Stator Plate

Figure: Magneto

Figure: Stator

Figure: Stator Plate

See: Figure: Magneto, Stator & Stator Plate

Function: Generates the voltage required by the spark plug to create the spark.

Material: The magneto is made of magnetized steel and brass. The Stator plate is aluminum and the wire coil is copper. A steel bracket is used to hold the wire coil.

Manufacturing Process: The magneto is made of two layers of metal and were forged together to make a single cylinder. These two sections were also riveted together. The center hole is splined with a broach. The stator plate was mold casted and had several holes drilled into it. These holes were tapped. The wire was drawn to its desired diameter and then wrapped to make a coil.

Model/Part Number: N/A

Fasteners

1 nut L=11 mm d=10 mm

Part Count: 1 magneto, 1 wire coil, 1 stator plate

Fasteners

2 Phillips round head screws D=10 mm
2 lock washers D=7 mm
2 Phillips flat head screws D=12 mm d=6 mm

Complexity: 4 This component has several parts and requires wiring. The magneto itself is also made of a magnetic material and is put together in a way that no other part of the dirt bike is put together.

Component: Crank Shaft and Connecting Rod

Figure: Transmission

See: Figure: Transmission

Function: Used to convert the power generated during combustion into mechanical power.

Material: steel

Manufacturing Process: The connecting rod is machine pressed. A lathe is used to cut the crank shaft to the desired diameter and to taper it down at one end. Threads were also cut into the shaft most likely with a lathe. The flywheels are cut from some cylindrical stock and then milled to the desired shape. They must also be drilled to create the axle slot.

Model/Part Number: N/A

Miscellaneous Information: There are two flywheels that “sandwich” the connecting rod. Additionally there is a ball bearing on both sides of the flywheel. The crank shaft is connected to the clutch, which is on the other side of the inner right transmission case.

Part Count: 1 connecting rod, 2 flywheels, 2 ball bearings, 1 crank shaft, I sprocket

Complexity: 4 There are several parts to this component that have unique manufacturing requirements. The flywheels must be made to have an uneven distribution of weight and the connecting rod has a more complex way to connect to the crank shaft than just sliding on. The parts are also in motion.

Component: Valve assembly

Figure :Valves

See: Figure :Valves (See also Figure: Spark Plug/Valve Covers)

Function: Allows fuel/air mixture to enter the engine and exhaust to leave the engine at the desired times.

Material: The outer cast is aluminum as well as the valve heads. The inner components are steel. The covers are also made of steel.

Manufacturing Process: The outer casing was mold caste. The case also consists of two rectangular covers that were mold caste and then machined. There is another circular cover that was pressed into its shape. The inner parts were machined by milling and drilling and were grind finished. Once the parts were made the entire assembly would be put together.

Model/Part Number: N/A

Miscellaneous Information: The interior components include two arms to engage the valves, valve stems including a spring in each, two ball bearings, axel, intake and exhaust ports, and fin-like heat vents like the ones on the cylinder casing.

Part Count: 1 Valve Assembly, 1 front cam shaft cover, 1 side cam shaft cover, 1 circular cam shaft cover

Fasteners

2x valve covers D= 4 cm
2x nuts L=5 mm D=9 mm d=5 mm
4x hexagonal flanged cap nuts D= 13 mm d= 6 mm
3x washers D=8 mm d=7 mm
1x washer (copper) D=8 mm d= 7 mm (looks as though this was a replaced washer)
2x hexagonal full thread tap bolts L=20 mm D=11 mm d=6 mm
1x hexagonal full thread tap bolts L=11 mm D=10 mm d=6 mm
1x washer d= 6 mm
1x hexagonal washer bolt L= 11 cm D= 10 mm d= 6 mm
1x hexagonal full thread washer bolt with Phillips slot L=20 mm D=10 mm d=5 mm

Complexity: 5 This part is complex because it has many moving parts that are all in close proximity. There are also several manufacturing processes that are used on all the parts. It also requires the parts to move during specific times.

Component: Head Gasket

Figure: Head Gasket

Figure: Head Gasket (Detached)

See: Figure: Head Gasket & Head Gasket (Detached)

Function: Seals the cylinder

Material: Plastic with a steel ring.

Manufacturing Process: machined with drills and mills.

Model/Part Number: N/A

Miscellaneous Information: N/A

Part Count: 1

Fasteners

2x sleeve L=14 mm d=7 mm
1x flanged sleeve L=10 mm d= 10 mm
1x rubber spacer d=19 mm
1x rubber spacer d=17 mm
1x washer D=15 mm
1x washer D=26 mm d=14 mm

Complexity: 1 Very simple manufacturing process and it only has two parts.

Component: Piston Head

Figure: Piston Head

See: Figure: Piston Head

Function: Creates the pressure barrier for during the combustion process and transfers that energy to the connecting rod.

Material: Aluminum with a steel cap on the side where combustion occurs.

Manufacturing Process: Various machining processes are used including milling, drilling, and pressing.

Model/Part Number: N/A

Miscellaneous Information: N/A

Part Count: 1

Complexity: 3 Though this component only has one part it has a complex manufacturing process that would require several steps. It is also made of two materials.

Component: Chain and Chain Tensioner

Figure: Chain and Tensioner

See: Figure: Chain and Tensioner

Function: Connects the cam shaft in the valve

Material: The arm of the tensioner is made of steel. The pulley guide and cam shaft sprocket are made of hard rubber. The chain is also made of steel.

Manufacturing Process: Pulley and spur gear were mold caste. The arm of the tensioner was pressing into its shape. The holes were drilled and rounded sections were milled. The chain was assembled after its individual sections were machined.

Model/Part Number: N/A

Miscellaneous Information: N/A

Part Count: 1 pulley guide, 1 cam shaft sprocket, 1 chain, I chain tensioner

Fasteners

1x click bolt

1x mounting bolt (black) L=10 mm D=17 mm d= 7mm

3x bolts L= 17 mm D=9 mm d=5 mm

Complexity: 3 None of the parts aside from the chain are very intricate, but there are enough parts that require a decent amount of manufacturing to make the total assembly somewhat complex.

Component: Centrifugal Clutch

Figure:Clutch

See: Figure:Clutch

Function: The clutch transfers power to the transmission when it is engaged and allows the engine to turn without transmitting power to the transmission when it is disengaged.

Material: Steel and a break pad

Manufacturing Process: machined

Model/Part Number: N/A

Miscellaneous Information: The clutch is composed of several main parts. These include friction pads, weighted arms, and extension springs. As the RPMs of the crank shaft increase the arms extend outward pushing the pads against the outer wall of the clutch, engaging it. As the RPMs decrease the arms retract and the clutch is disengaged. For more information see http://www.centrifugalclutch.org/index.html.

Part Count: N/A
Fasteners

4x Phillips round head screws L=12 mm D=9 mm d=5 mm
4x spacers
4x washers D=15 mm d=5 mm

Complexity: 4 The weight of the arms and the spring constant of the extension springs must be fairly precise so that the clutch engages and disengages at the proper times. Increased precision means more time must be put into each part of the component.

Component: Drive Chain Sprocket

Figure: Sprocket

See: Figure: Sprocket

Function: Final gear that puts the power from the transmission into the drive chain to rotate the rear wheel.

Material: steel

Manufacturing Process: Machined by drilling and milling

Model/Part Number: N/A

Miscellaneous Information: N/A

Part Count: 1

Fasteners

1x sprocket spacer
2x hexagonal full thread tap bolts D=10 mm

Complexity: 1 This is just a standard gear. It requires several machine processes, but is because it is only a single part it is not difficult to manufacture.

Component: Spark Plug

Figure:Spark Plug/Valve Cover

See: Figure:Spark Plug/Valve Cover

Function: Creates the spark for ignition in the cylinder.

Material: steel and plastic

Manufacturing Process: parts are machined and assembled

Model/Part Number: Torch A7RTC

Miscellaneous Information: N/A

Part Count: 1

Complexity: 3- Though it is only one part it has many sections including the terminal, ribs, insulator, casing, seals, threads, and electrodes. This entire assembly would require a decent amount of work to put together.

Component: Drain Pipe

Function: to drain the oil

Material: rubber

Manufacturing Process: mold cast

Model/Part Number: N/A

Miscellaneous Information: N/A

Fasteners

1x washer D=16 mm d=9 mm
1x nut D=14 mm d=8 mm
1x mount

Complexity: 1- plane rubber tubing.

Component: Oil Plug

Figure: Oil Plug

See: Figure: Oil Plug

Function: For refilling the oil

Material: plastic

Manufacturing Process: machined

Model/Part Number: N/A

Miscellaneous Information: N/A

Part Count: 1

Complexity: 1- Simple plastic component

Component: Spring Tensioner

Figure: Tensioner

See: Figure: Tensioner

Function: applies tension to the spring

Material: aluminum and has a rubber cap

Manufacturing Process: The tensioner has holes that are drilled and lathing is used to achieve the desired diameter. The spring is coiled wire.

Model/Part Number: N/A

Miscellaneous Information: N/A

Part Count: 1 tensioner, 1 spring

Fasteners

1x hexagonal full thread washer bolt L=14 mm D=16 mm d= 10 mm
1x mount

Complexity: 1- requires only basic machining processes

Component: Drain Bolt

Figure: Oil Plug

See: Figure: Oil Plug

Function: drains oil

Material: steel

Manufacturing Process: machined milling and a die was used for the threading

Model/Part Number: N/A

Miscellaneous Information: N/A

Fasteners

(This part is a fastener)

Complexity: 1- simple bolt

Component: Kick Start

Figure: Clutch Cover & Kick-Start

See: Figure: Clutch Cover & Kick-Start

Function: Initial power used to start the engine.

Material: Steel

Manufacturing Process: mold caste and machine finished. The hole in the lever was drilled and then the splines were broached.

Model/Part Number: N/A

Miscellaneous Information: The kick start is composed of four parts. It has two arms hinged together to make an “L” shape. There is also a bolt and washer.

Part Count: 1 kick start

Fasteners

1x hexagonal full thread tap bolt L= 23 mm D= 9 mm d= 5 mm
1x washer D= 20 mm d= 10 mm
1x lock washer D= 20 mm d= 10 mm

Complexity: 2- made of two parts, but is mold caste and requires only simple machining

Design Revisions

This system appears to be very well constructed (as judged by our limited knowledge.)Finding necessary improvements to the motor and transmission is difficult.

A primary revision that would be of great value to anyone who has ever used a screwdriver is simple, change all Philips head screws to Allen or slotted head screw. These screws are available, the price is comparable, and the chance of stripping a tightly set screw decrease.

A second revision would be to move the oil drainage port or create another one. It seems that the port is positioned too high to allow all the oil to drain out of the transmission casing. In order to fully drain it, the transmission casing must be tilted nearly 90 degrees from its normal position. If a port was positioned at the rear of the casing, it would most likely make this drainage process easier.

The third suggestion would require some testing. The magneto and ignition coil are positioned directly opposite of the centrifugal clutch. Sitting flush with the clutch is the main drive wheel in the transmission which transfers power from the crank to the transmission. If the magneto could be made slightly smaller in its diameter and height, it could be positioned above this sprocket. This would decrease the overall volume of the motor and allow it to be shifted toward the side the magneto is currently on. This would give more room for the drivers legs (allowing for the avoidance of the 'bow' legged position you must take on the bike, at least to some degree) make the bike lighter and most likely reduce the drag to some small degree.

This suggestion would require testing because it would change the center of gravity of the whole system and change the stresses on the new gear to which it is attached.

AutoCAD Model

Figure: Cylinder Arm 1

Figure: Cylinder Arm 2

Justification

The motor is fairly complex and no one in our group have any considerable amount of knowledge with solid modeling programs. To create the images above, one of our group members had to learn to use AutoCAD well enough to create them.

The Piston-Cylinder system was chosen because it was within the abilities of the team member to create, is composed of several parts (which satisfied the requirements,) and is a integral component of the entire system.

Engineering Analysis

Question: Choose a key component or function and explain how engineering analysis would be used in the design or testing stages of the design process. Provide a detailed description including relevant equations and processes that would allow an engineer to easily perform analysis.

Relevant Equation:

V = L dI (Equation 1)

Where:

V = Voltage (V)
L = Inductance (H)
dI = The rate of change of the current (A).

Ignition Coil "An ignition coil is essentially an auto transformer with a high ratio of secondary to primary windings. An "Auto-transformer" is a set of primary and secondary windings are not actually separated - they share a few of the windings" (How to use an Ignition Coil,http://www.sentex.net/~mwandel/cannon/sparky.html )

In the bike, the Ignition coil is designed to pick up magnetic signals whenever a Magnet crosses the coils’ pickup point. (This is located under the magneto, which rotates by taking mechanical energy from the crankshaft.) The changing magnetic field generates a voltage, which in turn, supplies energy for the spark plug to ignite fuel. The coil is grounded to stop the spark plug from multiple ignitions after start-up. The actual spark is generated when the breaker contacts open. For an ideal inductor, the current and voltage relate by Equation 1.

Since L is constant for the inductor, the abrupt change in current will cause a very short, very high voltage spike.

Analysis and Testing: Given the equation above, it is possible to test the ignition coils ability to supply a voltage by measuring the resistance of the low tension (secondary winding) and high tension (primary winding) wires and the ground (the ground for the wires is the coil-mounting bar that passes through the coil and mounts it to the frame.). There should be a huge difference in the resistance value. The low-tension wire should show a small value on the magnitude of a single ohm. The high-tension wire, which goes to the spark plug, should show a resistance on the order of several thousand ohms. The circuit for this system is relatively simple (see Diagram 1).

Creating this circuit with the proper resistance values would take basic engineering analysis in the testing stages. A multi-meter and a voltage supply would be needed to test the circuit’s connectivity and resistance values. Verifying that the circuit was connected according to the design and the resistance values were in the correct range could be found with a multi-meter. If it was found that the spark plug was not receiving enough energy to ignite the fuel, the coil could be changed such that the high-tension line had a larger inductance value and tested again.