Difference between revisions of "Group 24 - GM Inline Four Cylinder Engine"
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Latest revision as of 23:39, 15 December 2009
Executive Summary Over the course of the September through December we have been in the process of reverse engineering a GM 2.2L Four Cylinder Inline Engine. This process had four stages, with the first involving a basic overview of the capabilities of the group and inspection of the product. After this we dissected it and re-evaluated the time we believed would be required for the project. We then analyzed every component based on a series of criteria and modeled a few of the parts that we deemed to be of greatest importance. During this step we also analyzed the effect of a specific type of failure that our engine could have, a small leak in the oil pan. Finally we reassembled the entire product and insured that it worked as well as it did when we received it. This process has given all members of the group a much more in-depth understanding of the workings of a gasoline-powered engine. Although we were not able to actually test the engine, we were able to see everything that goes into the engine to make it run.
1. Request for Proposal
The first step in reverse engineering process is to take an initial look at the engine and estimate what will be required for this process. For this reason we have put together a work and management proposal, to cover the initial phase, product break-down. We have also created a road-map of where we believe we should be and when for the rest of the project. This plan can be seen in the Gantt chart in the management proposal.
Work Proposal has been moved here
Management proposal has been moved here
Initial Product Assessment
The product we have received is a GM Four cylinder in-line engine. The intended use of this product is, by definition, to use different forms of energy (in this case comes from fuels and oxidizers that undergo combustion to produce very high temperatures and pressures) to produce mechanical work or torque. This engine will produce mechanical work from the energy in the high-pressure high-temperature combustion chambers to spin the wheels, in most cases, on an automobile.
- This product would lie mainly under the field of home or personal use because of its commercial use in automobiles; however, this does not exclude this product from professional use. In fact, this product can be very helpful in professional use, whether in the use of research, company cars, or even to produce mechanical work in any innovative way outside of automotive use, such as using the mechanical work produced or torque to produce electricity or even power generators.
- The four-cylinder engine’s main function is to produce mechanical work for automobiles out of combustion, which produces high pressure and temperatures. The mechanical work, or torque, produced by the engine is used to spin the tires on an automobile. The other functions of this product will all relate back to the necessity of work. Whether linear or rotational work is needed; the engine can provide both. If rotational work is needed to spin the wheels on an automobile, to power a generator to produce heat or electricity, or if torque or mechanical work is needed to operate a large pulley or gear system, the the engine can perform the task.
How It Works
Most parts in an engine are designed to make possible or increase the efficiency of the cylinders. The explosive expansion of gases is what provides the force driving the output shaft. There are four steps for an Otto cycle engine to work. The fuel air mixture enters the cylinder via the open valve. A small starter motor drives the piston upward, compressing the mixture. This mixture is ignited by the spark plug once the cylinder has reached its maximum compression. The increased pressure from the mixture's combustion drives the piston down, providing energy to crankshaft. The gases in the cylinder are forced out through a second valve and then the process repeats, but the starter motor is no longer needed due to the momentum of the crankshaft.
There are many kinds of energies that are used and converted within a combustion engine. Electrical energy is used to power the starter motor, provide the spark to ignite the mixture in the cylinders and recharge the battery. Chemical energy can be found in the gasoline-air mixture which enters the cylinders for combustion as well as the material in the battery which provides electrical energy. Thermal energy is a result of the combustion process and is mostly a waste by-product. Mechanical energy can be found in all the moving parts of the engine, which is the ultimate goal of an engine. This mechanical energy is usually harnessed to do work such as generate electricity or move a vehicle.
When an engine is not running something must provide the initial energy to compress the mixture and ignite the mixture. For this reason modern engines have a battery to provide power and a small starter motor to power the first cycle. Chemical energy in the battery is converted to electricity and flows through the wires to the starter engine. This produces a magnetic field which spins the output shaft of the motor, converting electricity to mechanical energy. This rotational mechanical energy is converted by the piston connecting rod to linear motion, compressing the fuel-air mixture in the cylinder. The spark plug receives electrical energy from the battery which then ignites the compressed mixture, converting its chemical energy into thermal energy as well as creating a large amount of pressure against the cylinder and piston. This pressure moves the piston, converting it to mechanical energy. The piston's linear motion is converted by the connecting rod to rotation of the crankshaft. The gases in the cylinder leave through another valve, taking much of their thermal energy with them and dumping it into the environment. Once the crankshaft starts spinning the above process is repeated without further usage of the starter motor.
Without some major overhauling, our engine is destined to remain a paperweight. Many of the parts have had sections cut away to allow a view of the inside, rendering them unusable. Among the cut open parts are the oil filter, the main housing, the oil pan and many of the tubes have also been cut open. If we were to replace quite a few parts it would most likely function, but the cost and time required to accomplish this make it hardly a worthwhile task. Therefore, it will remain a large complex paperweight.
In current engine designs there are those considered to be extremely simple and others that are incredibly complex. On the simple end of the spectrum is the steam engine, a functional engine but very simplistic. Since the invention of the steam engine other more efficient and more powerful cycles have been discovered and put into use. Of the designs that are actually in use, the jet engine is the most complex. Its complexity is based on the engineering that has gone into the design of every piece in order to optimize its efficiency and thrust. Midway between these two extremes are two-stroke engines, four-stroke engines, diesel engines in order of increasing complexity. The two-stroke cycle is simpler but less efficient than the four-stroke and the diesel uses a different type of cycle entirely, relying on compression to ignite the fuel mixture. Our engine, on a scale of one to ten, with the given extremes, would probably be about a 6.
- There are innumerable nuts, bolts and small pieces that make up each component of our product. The outside shell is basically large pieces of steel from molds, held together with bolts and attached in some way to every other piece of the engine. There are pipes running into and out of this shell to provide fluid flow, whether that be air, exhaust, coolant, fuel, or oil. Inside the engine block are 4 pistons (1 per cylinder) with 2 valve assemblies per piston. The valves are opened and closed by the cams on the rotating camshaft. The pistons spin the crankshaft which then goes through a system of gears to provide the desired output. Among the other important parts are the oil pan, oil pump and oil filter, without which the engine would quickly cease to function. Our engine also contains a carburetor to regulate the blending of air gasoline that the cylinders receive. One final important piece of the engine is the spark plug, without which there would be no combustion.
- Engines as a whole are fairly complex, but when broken most of them are quite simple. The majority of parts in an engine are metal from molds, mostly steel with some aluminum. What makes an engine complex is the number of simple parts that it combines and how tight the tolerances are on these parts. Parts in an engine have very tight tolerances in order to prevent the leak of high pressure fluids. If the parts don't fit perfectly it is potentially hazardous as well as messy and inefficient. Although relatively simple in shape, every piece has been extensively tested and modified to optimize performance and efficiency.
The majority of the engine is made out of only a couple different metals, with the most highly used one being steel. Aluminum is used in our engine for a few different components, but it is not nearly as prevalent as steel. As with most systems that use electricity, the engine contains copper wires. Copper is also used for small pipes in a few locations. A few small components, like caps on pipes and snaps connecting wires are made out plastic, as well as the . Rubber is used in all the hoses on our product and covers for a few other components.Prior to our receiving it most of the oil was removed, but in the oil filter there is still a small amount of oil as well as the expected filter paper.
- Due to the holes cut in our product, more components are visible than would be seen in a functional engine. Steel makes up the majority of what can be seen, the entire outside shell is composed of it as are some of the components inside the engine block itself. Among other things, aluminum is used in the headers. Plastic coats all of the wires and is the material used in the caps on the oil reservoir and a few other things. Rubber and copper tubes provide fluid flow throughout the engine, with rubber forming the ones designed to be disconnected and moved easily. Copper and rubber also form the wires and insulation that connect the spark plugs and a few other components which require electric power. Oil and filter paper can be seen in the cross-section of the oil filter.
- We know that the engine contains spark plugs, so therefore there is a small amount of porcelain. In addition to what we can see, we know there is a lot more steel and aluminum in use. Aluminum camshafts and pistons are used, and the springs on the valve assemblies are made out of steel.
If I had to use this product I would be very happy with it. The majority of the developed world's population rely on engines very similar to this every day for transportation. This engine and others very similar to it provide power to personal generators, cars, and most anything which runs on gasoline. Every time I've used a gasoline-fueled engine I have been very happy with it, given that the alternative is performing the same task by muscle alone.
- Engines are not thought of by most as being particularly comfortable. However, very few would say that their engines cause them any amount of discomfort either. Therefore, we can temporarily conclude that engines fall at about a 5 when it comes to comfortability. While during operation they make a fairly large amount of noise, this is offset by the use of sound-deadening materials. As a result, the sound of the engine is barely noticeable when driving. Because driving provides an immensely more convenient and comfortable way of traveling than by walking, this ups the overall comfortability to about a 7 or 8 since there are no real drawbacks.
- The ease of which this product can be used varies somewhat from person to person, but for the most part, is considered quite simple. Starting a properly functioning engine inside a well running automobile consists of inserting and turning the key. There are other small requirements that must be met, such as having the car in park, but for the most part it is as simple as a twist of the hand. For someone with no basic training (and therefore a lack of the knowledge above), getting the engine to start could be a small challenge, but for anyone with a driver's license it is incredibly easy to use and takes virtually no thought.
- An engine requires a few different types of "regular" maintenance. The first type would be something that often, such as filling the tank with gasoline. This is something that anyone who drives is capable of doing. The other type of "regular" maintenance is that which is not required often, but follows a regular cycle, such as once every x number of miles. This includes changing the oil, filters, and hoses. While these are not incredibly complex, the average person does not have the knowledge and experience to know how to do such tasks. Most people take their engines into a shop to have it done for them by trained professionals.
Although the gasoline engine has become the most common, there are many different alternatives, each with their own advantages and disadvantages. The gasoline engine is by far the most common because of a combination of its complexity, cost and power output. Currently hydrogen and electric motors are the new big things in the field of automobiles, while steam was abandoned long ago and nuclear power cannot be safely used on a small scale such as a car safely or effectively. Currently electric motors are used for small portable tools, with gas engines being used in the higher end versions of these same tools. Hydrogen is being tested in vehicles but is not main-stream yet. For cars, at least for a few more years, gasoline engines will continue to be the standard. They are cheap compared to hybrid's, have a tried and true design and greater efficiency can still be pushed out of them.
- Steam engines were the pioneer for gas, they used steam to push a pistons forward and backward, thus producing double the power produced by a conventional gas engine which only gets one power stroke. Unfortunately, steam engines were given up for gas engines and not engineered much after that so they lack power and reliability compared to gas engines.
- On the other side of the spectrum, jet engines are some of the most advanced and powerful made to date. Since they are so powerful thought they are rarely used for anything but airplanes and they are very expensive to build maintain and run.
- Electric motors have arguably been gasoline's main competitor from weed-whackers to cars, as they are a clean, efficient motor with instant power and very reliable, but very few are able to match the power output of gas motors. The biggest downside to electric motors is that they need batteries to power them which becomes a chore when powering large machines.
- After those comes diesel motors which have been around about as long as gas motors, yet they have been used mostly for heavy loads, such as 18 wheelers, submarines, and earth moving vehicles. Diesel engines are very powerful, do not require spark plugs, and the fuel is usually more resistant to price fluctuation. However, the engines are louder, have a distinctive smell, and do not work well in cold conditions.
- Another power source is a nuclear reactor. Unfortunately they are not very efficient, produce radioactive waste, cost far to much for commercial use, and are extremely large. Though they are an alternative, it looks very unlikely that nuclear power will become main stream anytime in the near future.
- Finally, the newest technologies have yielded a new style of motor which is hydrogen powered and has the possibility to replace the gas engine. Hydrogen power is clean, efficient, and the only byproduct is water, but the technology is still new and will need years to be engineered and adapted to become a threat to the gas engines. Also, the threat of how reactive hydrogen is becomes a safety risk in the event of accidents.
2. Preliminary Project Review
At this point we have done an initial overview of the project and given estimates as to the time required for each step in the process. At this point we took apart the engine and documented each step in the process. Once this was completed we made the necessary revisions to our gantt chart based on the actual time things took compared to what we expected them to take.
Product Dissection Plan
This product is not something that is considered easy to take apart. It has many small pieces, and if things are not kept track of and organized when being removed, putting it back together becomes a nightmare. Also, upon reassembly things need to be tightened and attached very specifically in order for the engine to function properly. Because of this most people take their engines in to a shop to be worked on by professionals. While we are by no means professionals, the product does not have to be returned in working condition (since it did not function upon receiving it).
Bolts of various sizes hold most of the pieces of the engine together. This is because bolts are sturdy, yet removable, and can also be adjusted with a few twists of a socket wrench. All three of these are essential, due to the fact that engines must be solidly built, but also must be capable of being dissembled and adjusted when problems occur.
The tools needed for this project were exactly what we expected, no other tools were needed for dissection. As expected the engine was already on an engine mount, giving us easy access to any part of the engine and allowing us to turn the engine over to get at the bottom. Crescent wrenches and a socket set were used to unscrew every bolt and nut, with none requiring any other tool. For disassembly the pliers proved unnecessary, all nuts and bolts were easily accessed with sockets or crescents. As expected, the mallet was required to get the bearing mounts off the crankshaft and to get the pistons out of the cylinders.
The chart below is a guide to taking an engine similar to this one apart. Included are difficulty rankings for each step, ranging from “1” to “3”. Where:
- The part required very little effort to remove, usually involved unscrewing a few bolts or pulling the piece off.
- The part requires some effort to remove, usually hard to reach bolts or parts that require force to remove
- The part is difficult or time-intensive to remove, usually due to tight spaces within the engine making it difficult to remove a part or many long fasteners
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Causes for Corrective Action
Our group sat down before even beginning to take the engine apart and decided how we would go about doing this in an organized and efficient manner. We realized that, when it came to an engine, the planning would be more important than the actual disassembly. Our first action was getting into the lab and looking at what we had to work with. Adam, the car expert of the group, outlined the general plan for which we would go about taking the engine apart. We later went back and began taking it apart piece by piece, starting from the outside and working our way in. As we went along we kept notes of the order of which each piece was removed. The pieces were then bagged, and a description of the piece, as well as what tool was used to remove it, was placed on each bag. This plan worked perfectly, as by doing so we essentially already had the disassembly chart (seen below) done. By reversing those steps and following the information on the bags, we will be able to easily reassemble the project when the time comes. In this way we have already overcome many of the future problems we potentially could have come across by staying organized and adhering to the original plan, which called for “removing each piece in the order which they are available” and “labeling and keeping track of part regardless of size and shape."
3. Coordination Review
After completion of the product disassembly each piece must be analyzed for various characteristics as well as an assessment of that part's complexity. For this reason we have put together a chart of all the parts with the information as well as a short summary answering the important questions about the part.
For this we created a table of all the parts and came up with a rating system of the complexity of each part. Parts with a complexity of are are simple, either having a very simple shape or requiring very few processes to create. Parts with a complexity of five are incredibly complex, requiring many processes to form and a very intricate shape. As expected, anything between these two extremes has characteristics of both, with three being an even mix of the requirements of the two extremes.
Exhaust Pipe - Sand molded steel is used for high wear resistance. No force is applied to this component except its weight. This component requires a particular shape, in order to connect other parts. However the shape does not affect the manufacturing prcoess. Sand mold is used to make this component because of good accuracy and low cost. It is a functional component.
Intake - This component is made by plastic. So the temperature of fuel and air mixture is not easily affect by the engine. No force is applied to this component except its weight. This component requires a particular shape to control the flow rate of fuel. The shape does not affect the manufacturing process. Injection mold is used to make this component because of good accuracy and low cost. The manufacturing process would be more complicated if it is not made by plastic. It is a functional component.
Head Gasket - Steel is used for strength. A partial of force generated by combustion will transfer to this component. This component requires a particular shape to fit between parts. The shape does not affect the manufacturing process. To manufacture this part can simply stamped and cutted to desired shape. The manufacturing process would be the same regardless the chosen metal. It is a functional component.
Dip Stick Tube - Painted steel is used for low cost and wear resistance. No force acts on this component except its weight. It does not require a partiuclar shape as long as the dip stick is fitted inside. The shape does not affect the manufacturing process. This part is machined, bended from a tube, for low cost. The manufacturing process would be the same regardless the chosen metal. It is a functional component.
Dip Stick - Plastic and steel were used for low cost. No force acts on this component except its weight. This component does not require a particular shape. The shape does not affect the manufacturing process. This part is machined, cutting out from a large piece of metal, so the cost would be very low. The manufacturing process would be te same regardless the chosen metal. It is a functional component.
Oil Filter - The component is made up of steel and filter paper. No force is applied to this component except its weight. This component does not require a particular shape as long as it does the job. The shape does not affect the manufacturing process. It is machined, bended and cut from a piece of metal, for low cost. The manufacturing process would be the same regardless of the chosen metal. It is a functional component.
Distributor - Aluminum transfer electricity to the spark plug. Plastic insulates aluminum from other component of an engine. No force acts on this component except is weight. This component does not require a particular shape. The shape does not affect the manufacturing process. This part is molded plastic for good accuracy. The manufacturing prcoess would be more complicated if it is not made by plastic. It is a functional component.
Distributor Mount - Aluminum is used for low cost, very little force is acted on this component since it just holds distributor in place. It requires a particular shape depending on the distributor. The shape does not affect the manufacturing process. It is died cast for high accuracy. The manufacturing process would be the same regardless of the chosen metal. It is a functional component.
Distributor Mount Gasket - Aluminum is used for low cost. No force is applied to it except its weight. This component requires a partiuclar shape to hold distributor in place. The shape does not affect the manufacturing process. It is die casted for high accuracy. The manufacturing process would be the same regardless the chosen metal. It is a functional component.
Spark Plug Wire - Copper is used for transfer of electricity, rubber and plastic insulates copper from other components. No force is applied to it except its weight. It does not require a particular shape. Wires are encased in plastic and rubber. The manufacturing process would be the same regardless the chosen metal however it would affect the performace. It is a functional component.
Header Cover - Aluminum is used for low cost. It seals header, therefore some force created by combustion will transfer to it. This component requires a particular shape to do its work. The shape does not affect the manufacturing process. It is die casted for high accuracy. The manufacturing process would be the same regardless the chosen metal. It is functional component.
Coolant Tube - Steel is used for low cost. No force is applied to it except its weight. This component does not require a particular shape. The shape does not affect the manufacturing process. This part is machined, bended and machined to desire shape, becuase of low cost. The manufacturing process would be the same regardless the chosen metal. It is a functional component.
Oil Pump - Aluminum is used for low cost. No force is applied to it except its weight. This component requires a particular shape. The shape does not affect the manufacturing process. This part is partly die casted for high accuarcy. The manufacturing process would be the same regardless the chosen metal. It is a functional component.
Oil Pan - Steel is used for strength. It is painted to increase wear resistance. No force is applied to it except its weight. This component does not reqire a particular shape. The shape does not affect the manufacturing process. This part is machined, cut out from a metal and bended to desire shape, for low cost. The manufacturing process would be the same regardless the chosen metal. It is a functional component.
Piston Bearing - Aluminum was used for low cost, little force is applied to it since it hold connecting rod in place. This component requires a very particular shape to connect other parts. The shape does affect the manufacturing process because of the size. Machining would give a high percentage error. This part is die casted for high accuarcy. The manufacturing process would be the same regardless the chosen metal. It is a functional component.
Piston Head - Aluminum was used for strength. A high magnitude of force created by combustion process transfer through piston head. The shape of this component is very important. The shape does not affect the manufacturing prcess. Die casted process is necessary for high accuracy becuase it has to be perfectly fit the cylinder. The manufacturing process would be the same regardless the chosen metal. It is a functional component.
Piston Connecting Rod - Steel was used for strength. It transfers the force generated from combustion process to the crank shaft. This component requires a particular shape to connect other parts. The shape does not affect the manufacturing process. It is sand casted for lower cost and good accuracy. The manufacturing process would be the same regardless the chosen metal. It is functional component.
Crank Shaft Bearing - Aluminum was used for low cost. The rolation and virabation of crank shaft create a force acting on it. This component requires a partiuclar shape to connect other parts. The shape does affect the manufacturing process because of the size. Machining would give a high percentage error. It is die casted and machined for high accuracy. The manufacturing process would be the same regardless the chosen metal. It is a functional component.
Engine Block - It is the housing for internal combustion. Steel was used for strength since the expansion of gas would create an enormous force to the surrounding. This component requires a particular shape, so other parts would fit inside. The shape does not affect the manufacturing process. This part is die casted and machined for high accuracy. The manufacturing process would be the same regardless the chosen metal. It is a functional component.
Crank Shaft - Steel was used for strength. A large amount of forces acts on it from the cylinders. It requires a particular shape to connect other parts. The shape does not affect the manufacturing process. This part is sand casted for low cost and good accuracy. The manufacturing process would be the same regardless the chosen metal. It is a functional component.
Rocker Assembly - Steel was used for strength and low cost, very little force is applied to it. It requires a particular shape to connect other parts. The shape does affect the manufacturing process because of the size. Machining would give a high percentage error. This part is die casted for high accuarcy. The manufacturing process would be the same regardless the chosen metal. It is a functional component.
Push Rod - Steel was used for strength, very little force tranfers from crank shaft through push rod. This component does not require a particular shape. The shape does not affect the manufacturing process. This part is machined, a piece of metal is cut to a desire, for low cost. The manufacturing process would be the same regardless the chosen metal. It is a functional component.
Coolant Valve - Steel was used for strength and low cost. No force is applied to it except its weight. This component requires a particular shape. The shape does not affect the affect the manufacturing process. This part is sand casted for low cost and good accuracy. The manufacturing process would be the same regardless the chosen metal. It is a functional component.
Spark Plug - Porcelain and Steel were used for conduction of electricity. No force is applied to it except its weight. It does not require a particular shape. The shape does not affect the manufacturing process. This part is machined to desire shape because of low cost. The manufacturing process would be the same regardless the chosen metal. It is a functional component.
Metal Bracket - Steel was used for strength. No force is applied to it except its weight. The painting process can increase its wear resistance. It does not require a particular shape and the shape does not affect the manufacturing process. This part is machined, cut from a large sheet to desired shape. The manufacturing process would be the same regardless of the chosen metal. It is a functional component.
Header - Steel was used for strength and low cost, very little force is actually applied to this bracket. It require a particular shape. The shape does not affect the manufacturing process. This part is cut out of a large sheet and bent to the desired shape and then painted. The manufacturing process would be the same regardless of the chosen metal. It is a functional component.
An enormous amount of time and energy has already been spent by professional engineers to optimize this engine for the intended audience and usage. This being said, we believe a few revisions could be made to increase efficiency and performance. These modifications can be done by the end user or by revision to the molds used to make the parts.
- The first design revision is to expand the holes of the intake. Larger holes would increase the amount of air flowing into the engine, which allows for more oxygen to mix with fuel in the engine. This results in a more powerful combustion reaction, increasing the engine's horsepower and overall performance. If done by an individual this is a very simple and easy modification which will noticeably increase the engine's performance. For the manufacturer to make the change would be a fairly expensive change, requiring a new mold to be used with the changes made. If this change is made in conjunction with the old mold needing to be replaced it would not increase the cost to them much and would provide the user with a better product. The changes would have to be made to the intake ports on the engine block as well as to the plastic tubes that make up the intake system. Unless the company is getting new molds this revision does not make sense due to the high cost of getting a new mold.
- Our second design revision is to increase the diameter of the exhaust pipes coming out of the cylinders. An increased bore size can greatly increase the flow of exhaust gases out of the cylinders, reducing the work done by the crankshaft to remove the exhaust and decreasing the amount remaining in the cylinder for the next cycle. Both of these things will increase the efficiency and thus the power output of the engine. This revision would require some simple design modification, increasing the hole diameter in the block for the exhaust and increasing the diameter of the pipes leading from the engine. This change would require a new mold to be used for the engine block, so it is a fairly costly change for them to make.
- Our third design revision is to increase the distance of the intake system to the engine block or to put heat shielding between the intake and the engine block. This revision will decrease the temperature of the air being put into the engine which yields multiple desired results, power and efficiency. By lowering the temperature going into the cylinder we get a more efficient combustion process, yielding more horsepower from a given amount of fuel. This change does have the drawback of increasing the size of the assembled engine or increasing weight, but for many applications the increased size would not prove a problem.
Solid Modeled Assembly
Of the many components of an engine to choose from we selected a piston for our solid model. A piston is a very key component to an engine, in addition to being one of the more commonly recognized parts of an engine to the average person. In addition due to our lack of any specialists in the field of 3D solid modeling it was convenient to select a part of moderate complexity, in order to solid model the part we needed to be able to transport the part which was easy being that we selected the engine piston. These reasons all factored into why we selected the piston for our solid model.
As for our selected CAD package, we decided to go with Autodesk Inventor. This was one of the most user friendly, easy to learn packages readily available. It has a free downloadable student version, giving members of the group access to the software from their own computers requiring people to go to a computer lab. Another reason we chose this was that members of the group had some experience with the software and With a downloadable student version available for free online, and group member would have access. In addition, we had people within access, with prior knowledge on how to use inventor which would also help our group in the long run.
An important part of creating a product is designing it so that it can stand up to extensive wear and tear in the real world. Consumers are not known to take good care of things that they purchase, resulting in an enormous number of products designed for the purpose of protecting consumer products from the carelessness of consumers. In the design and testing stages engineering analysis is used to find weak points in a product and remedy them. This can be done by physically testing a product, usually with an automated system that tests the product as a whole or specific components of it. Parts are also analyzed for weaknesses before they are built using sophisticated modeling software and its ability to simulate forces acting on pieces of the desired material. This does use ideal properties of the objects, but is a good test of a part's strength.
A problem that occurs relatively frequently in consumer automobiles is an oil leak. It could be caused by damage to any part with oil flowing through it or any point that is not sealing correctly and is allowing some fluid through. In either case the engine is losing vital oil and will tear itself apart if the level drops too low. Here we are evaluating how long it will take for a slow leak to reduce the amount of oil to a dangerous level. We are assuming that the speed of the leak is constant and unrelated to the remaining volume of oil. We are also treating oil as an incompressible substance
Starting volume of oil: 4.5 quarts (260 in^3)
Dangerous volume of oil: 2.5 quarts (144.5 in^3)
Hole diameter: 0.1 inches
leak speed (v): 1in/min
As can be seen above, even a very small leak can quickly reduce the volume of oil available in an engine to dangerous levels. The decreased volume will also tend to have a higher percentage of foreign particles in it such as metal shavings from metal wearing and soot from the cylinders. Depending on when the car last had its oil changed, the minimum safe volume of oil could be significantly higher than what we assumed for this problem due to the amount of junk mixed in with the oil.
4. Critical Design Review
At this stage in the project reassembly of the unit takes place as well as an assessment of its current condition compared to the condition it was initially in. This is the last major step in the process, with the next step being to put together a presentation giving an overview of the entire project and making any necessary revisions to the Wikipage.
As expected, the tools required for reassembly are almost identical to those required for dissection. A socket set and crescent wrenches were used to tighten all the bolts ranging from 8mm to 16mm. A special tool was required to compress the rings on the piston heads which was not needed during dissection. Pliers were useful for one part that needed to have one part remain still while another turned. The mallet was needed to get the pistons into place. No other tools were needed for reassembling the product.
We rated the difficulty of each step on a scale of one to five with one being very simple and five very complex. A complexity of one means that it was very straight forward to perform this step of reassembly. This means there were very few parts to reattach, they did not require special tools and positioning of the part is fool-proof. A complexity of five means that the part required special tools to reattach, part location or orientation was not sure even with excellent documentation, it may also mean that there were a large number of parts with slight differences among them.
Q. Does your product run the same as it did before you disassembled it?
A. Without replacing a significant number of parts our engine is destined to remain a paperweight. Many of the parts have had sections cut away to allow a view of the inside, rendering them unusable. Among the cut open parts are the oil filter, the engine block, the oil pan and the headers. If we were to replace all of these parts it would most likely function, but due to the cost in time, labor, and parts it would be more economical to simply replace it.
Q. What were the differences between the disassembly/reassembly processes? Were the same sets of tools used? Were you able to reassemble the entire product?
A. We were able to entirely reassemble our product, everything went back together the way it came apart. For the most part assembly was identical to disassembly but in reverse. Putting the pistons back in took a special tool to compress the rings which was not needed during disassembly. Other than that one tool the tools used were identical. A combination of sockets and crescent wrenches enabled us to put the entire thing back together.
Q. Are there any additional recommendations your group would make at the product level (operation, manufacturing, assembly, design, configuration, etc.)?
A. The one thing that could be simplified would be the number of different socket sizes that are needed to handle all of the nuts and bolts. Often we would be working with one size socket and then the next set of bolts would require us to use the size 1mm larger or smaller. Simplifying their system so it only used 2 sizes instead of 5 would greatly reduce the number of tools needed to put the engine together. As a whole the product seems well designed and the process for manufacturing seems streamlined. There were a few spots on the engine where it looked like something could be attached, which we can only assume is due to this engine design being used for a variety of tasks. They could remove these unnecessary features but that would require a different mold for the engine block for other purposes.