The Cooling System

Photo courtesy of dakotak.com

The several engine processes previously discussed are how the engine runs, but what keeps it running are almost separate entities entirely. The additional system I’ll be investigating is the cooling system.

What does the cooling system do other than the obvious? Essentially it is what keeps the engine from seizing; it keeps the parts moving and functional. This process happens I a few steps:

Internal combustion causes an immense amount of heat to be expelled on the surrounding machinery in an engine – this fact actually is beneficial because the engine coolant allows the most engine-efficiency when it’s around 200 F (93 C). Without the cooling system the engine easily approaches 4,500 F. While the coolant is necessary, it’s still more efficient for the engine to run “hot:” This allows the most efficient combustion of fuel (allows the air/fuel to vaporize in the cylinder), it increases oil viscosity allowing for the most effective lubrication of moving parts, and the metal parts wear less.

Cooling systems are either liquid or air based: Air cooling is more typical of older vehicles (old Volkswagon Bugs or buses). These function by having the engine block covered in aluminum fins that help circulate air from a fan through the engine and conducts heat away from the it. Liquid cooling systems, on the other hand, circulate a liquid coolant through a series of pipes through the engine block. The fluid absorbs heat put out by the engine and moves it through a series of paths. Nearly all current vehicles are liquid based cooling systems. Lets further investigate the pathways the coolant can take.

Photo courtesy of troubleshootengine.com

The coolant fluid begins at the pump. Once the engine starts, the pump sends the liquid to the engine block via plumbing, and from the engine block it’s sent on a return path through the cylinder heads. At the exit of the engine block a thermostat is located: the thermostat is an open/shut valve. Once the engine has reached a certain temperature, the thermostat opens allowing fluid to be cycled through the radiator to be re-cooled and returned to the pump. Until the engine has attained that temperature however, the thermostat is in a closed position and the fluid is returned directly to the pump. On certain cars, the radiator has a built in cycle for cooling the transmission where oil is pumped into this portion of the radiator.

This simple overview of the cooling system is what keeps the engine functional: if the cooling system were to malfunction, the heat within the engine block could allow the pistons to become so hot that they weld themselves to the cylinder heads, among other potential issues. This is why cooling is so important, and why the radiator needs to be kept in good working order. 

 

 

 

Sources: howstuffworks.com

troubleshootingengines.com

 

The Starting System

The final component of the engine process that I will be investigating is the starting system.

The smaller portion on top is the solenoid, and the bottom portion is the starter motor.
Picture courtesy of howstuffworks.com

What exactly does the starting system consist of? There are two typical pieces: the starter motor and the starter solenoid. The purpose of the starting system is to get the engine running and the four stroke (depending on your engine) cycle going. The starter solenoid does this by sending a large amount of current from the battery to the starter motor. The solenoid can be thought of as an electrical switch engaged when one turns the key to the ignition. When you turn your key as far as it goes, you send a small amount of electricity from the ignition to the solenoid. This electricity closes a circuit from the battery to the solenoid and a much larger surge of electricity passes through the solenoid to the starter engine. The starter engine has power to rotate, and when it rotates it starts the pistons moving in their stroke process, which begins the automated fuel injection, carburetor or whatever type of fuel delivery system the respective engine has. This surge of electricity has to be extreme, because it has to overcome so much of the internal friction. For example, the starter motor must be able to kick start the normal cycles of the engine by overcoming any internal friction between the pistons and cylinders, any built up compression of any one of the pistons that may be in the compression stroke, and any other added weight of the other parts that make the engine move. So after the solenoid has had the surge of electricity from the battery, the electricity delivered via the ignition switch (your key) is no longer necessary, and does not need to be held in the fully turned position. All it needs is to maintain the closed loop with the car battery, so the solenoid is disengaged and the starter motor stops. 

https://www.youtube.com/watch?feature=player_embedded&v=IVJxP1NAcow

This is a short clip showing the starter motor engage the engine.

 

So as an overview, to get the engine going, the following steps ensue:

• The key is turned in the ignition sending electricity to the solenoid, which in turn allows electricity (large magnitude) to flow to the starter motor
• The starter motor starts and spins at a high rate (see video above) engaging the engine
• The engine rotation begins the valve train rotation, which begins the piston movement and the stroke cycle
• Simultaneously the fuel system begins feeding the air-fuel mixture into the cylinders
• Also at the same time, current from the battery flows to the ignition coil amplifying the electricity distributed (by the distributor) to the spark plugs
• All of the spark plug firings are timed at the peak of the compression stroke as the combustion stroke and these thousands of explosions of the compressed air/fuel are the energy that drives the engine and the vehicle itself
• And while I have neglected to cover other important features of the engine (the cooling system, the way fuel is delivered to the pistons, etc.) the overview should provide a decent picture of the general inner workings of a typical engine. 

The Ignition System

Here we have all the basic components of the Ignition.
Photo Courtesy of wikipedia.com

The final components that make up the ignition system involve the following parts: The ignition system coil, the distributor, and the distribution system. We’ll begin by looking at the ignition coil.

Photo Courtesy of Maglab.com

The ignition coil can be thought of as a high capacity transformer: basically just a way to transform a decently strong current to extremely high electric potential. The coil consists of two sets of wrapped wiring; a primary and secondary. The secondary is wrapped much tighter and wound with much higher frequency than the primary. Current flows from the car battery to the primary wire. This current flow induces a magnetic field in the secondary wire causing a huge spike in electric potential, completing the necessary transformation. The secondary wire feeds this high voltage current to the distributor. 

Photo Courtesy of autorepair.com

The distributor is a highly precise piece of technology which takes the high voltage and distributes this power to each piston in its cycle of ignition. The distributor has an internal rotor that closes electric circuits linking to individual spark plugs in each cylinder. As the rotor spins, it makes a contact per cylinder every rotation; however it does not touch each contact as this would introduce wearing into the system and necessitate much more frequent replacement. The rotor (and cap enclosing it) does need to be replaced during vehicle tune ups because of the arcing current between each contact does eventually dull and upset the timing of the combustion cycle. 

Other components contributing to spark timing in the distributor are the breaker points. Inside the distributor on the bottom half, here is a cam (button) tied to each connection point which acts as a ground for current; the ground is important for spark timing because it dissipates all unnecessary current and saves energy. When the rotor makes contact with the coil – sending a current eventually to its respective spark plug – the cam is depressed which makes it lose its ground and closes the circuit so the spark plug can be fired. This timing, as stated previously, is so vital for the engine to properly function. Most of the engines being made now opt for computer-dictated spark firing rather than these breaker points. Computerized circuit closings allow a much higher degree of precision because the program will tell the distributor where the piston is and can fire the spark plug at exactly the ideal moment of compression. 

The Spark Plug

Photo courtesy of http://classicmechanic.blogspot.com/

We’ve discussed how the main mechanics of the engine function and once in motion, how power is provided to move the car. Now we will look into how these mechanics get going and how electricity and the car battery ties into working the engine. 

Arc of electricity jumping the gap:
Photo Courtesy of autocareexperts.com

Without the electrical system and distribution process, the engine cannot function. The vital part of piston movement and the four-stroke process mentioned briefly before this is the spark plug, which is where delving into electricity will begin. The spark plug, as mentioned in the four-stroke post, is the mechanism which ignites the compressed air-fuel mixture and causes the fuel to combust internally powering the entire engine process. The spark plug causes high voltage arc of electricity to cross a gap between the ceramic insulator and a metal extension within the area of the air-fuel mixture. This arc creates a spark, this spark ignites the mixture. The arc must be focused, and therefore on the interior the spark plug core (electrode) has a ceramic coating forcing the electricity to escape only at the tip of the electrode.

Photo courtesy of Howstuffworks.com

Depending on how high efficiency an engine is and how much heat is created by the stroke processes, a cold or hot spark plug may be needed. The difference with these two plugs is simply that the ceramic coating is less restrictive on the electricity’s exit path (the tip is shorter for the cold), which causes more dissipation, leading to a colder spark. This type of plug is more common in high efficiency cars in which not very much heat is required to ignite the mixture due to the heat levels already contained within the engine. 

Timing is very important for spark plug firing: if the spark plug fires too early before the fuel mixture has compressed, or it fires too late after the piston has passed maximum compression of the mixture it will lead to engine problems. The system that controls this firing of the spark plug is housed within another portion of the ignition system: the distributor cam, which will be discussed next week. In summary, you can think of the spark plug as a high precision, high intensity bolt of lightning making contact with the fuel mixture during the combustion stroke, which will occur with more frequency as the engine works faster. 

 

Sources: Howstuffworks.com

autocareexperts.com

gm.com

Pieces Comprising The Otto Cycle

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Photo Courtesy of hepdoco.com

After viewing the Otto cycle, the next logical step in understanding the inner workings of an internal combustion engine is to look at how and what parts make this four-stroke process work. Starting with the cylinders. 

The cylinder is the core of the engine housing, wherein the piston moves up and down/back and forth during the stroke cycle. In each typical engine housing for vehicles, there are at least four cylinders (hence the translation of more horsepower or speed with more cylinders), but can be as many as eight in the common engine. Cylinders are arranged (commonly) in a variety of ways: inline, V, or flat. 

Inline Cylinder
Photo Courtesy of ustudy.in

Flat Cylinder
Photo Courtesy of caranddriver.com

Different arrangements depend on the cost of manufacturing, smoothness, shape, and overall number of cylinders.

A: Piston Head
B: Piston Ring
C: Connecting Rod
Photo Courtesy of motorera.com

Inside the cylinder pumps the piston which is a metallic cylindrical object, typically contained within piston rings.These rings act as sealants within the cylinder and also as friction reduction for the piston on the cylinder surface. The sealant is to prevent the air-fuel mixture from escaping the small compressed area formed between the piston and the upper end of the cylinder during the stroke cycle. The other portion the rings provide sealant for prevents oil from the sump from seeping into the stroke portion of the combustion cycle and being burned and lost. This is why we have our oil changed every certain number of miles, especially on older cars. The oil in the sump seeps into the combustion process and is burned away, necessitating its replacement. The piston itself is connected to an aptly named connecting rod. The rod has pivots at both ends which allows for movement even when the rod changes its angularity with the piston. This portion is connected to a major part of the engine: the crankshaft. 

Crankshaft
Photo Courtesy of motorera.com

The crankshaft is a piece of tooling that converts the piston’s lateral motion into rotational motion of the engine. The pivots on the connecting rod allow this rotation which is used in converting the piston motion to vehicle movement. The crankshaft is surrounded by the sump (oil pan) which helps lubricate and collects excess oil at the bottom. 

 

Sources:

howstuffworks.com

carandriver.com

 

 

 

 

Car Engine: Internal Combustion

Source: http://www.grc.nasa.gov Four-Stroke Engine Image

Of the numerous types of engines, specs, and variations of a car engine, there are two typical broad categories which combustion engines fall into: internal, and external. For our purposes, we will focus on the internal combustion system, being as external combustion engines were most typically used for trains and steamboats predominantly where combustion happens externally, and the steam from the combustion is then forced into the engine process to power the engine. The problem with using external combustion for a car engine is size, efficiency, and most recently, pollution concerns. Therefore, internal combustion (combustion of fuel happens inside the engine) is more popular. Internal combustion is much more fuel-efficient and allows for much smaller compact engines. The basic idea of an internal combustion engine is this: pack a very small amount of high energy fuel into a small enclosed space, ignite it, and this combustion will release a huge amount of energy in the form of gas. As much energy as this reaction releases, it’s not nearly enough to power or run a car. To remedy this, the process happens hundreds of times every minute.

How do engines repeatedly create explosions? The most typical way that cars today convert fuel into energy is through the four-stroke combustion cycle, known also as the Otto cycle. This cycle consists of the following four stages:

Source: Author

Let’s examine each in more depth:

1. Intake: The piston (in the figure, the blue portion that moves) is depressed allowing for the intake of a fresh amount of fuel/air mixture. A very small amount of gasoline needs to be mixed with the air for this reaction to work.

2. Compression: Once the gas/air mixture is inside the cylinder, the valve – or poppet-which allowed the fuel to be drawn in is closed. The piston then completes an upward motion compressing the fuel and air into a very small volume of space

3. Combustion: Known also as ignition, once the fuel and air has been compressed, the spark plug ignites the fuel which creates a miniature explosion.

4. Exhaust: The explosion of gas forces the piston again into a downward motion. This pressure change opens the exhaust valve and on the final upstroke of the piston the combusted fuel is propelled out the exhaust.

This is the basic workings of the Otto cycle, which just a small part of how an engine works: but it is the portion that converts fuel to work and mechanical energy.

Note: Figure 1-4 obtained through animatedengines.com

Sources:

howstuffworks.com

animatedengines.com

http://www.grc.nasa.gov

Human-Powered-Charger: The Atom

Transforming movement into energy is not a new concept, in fact it’s the basis of much of the energy progression we’ve had in the past century. Innovation on the matter continues, as the energy company Siva Cycle has just developed an extremely efficient and inexpensive generator for the layman: or rather, the lay-biker. The “Atom” is a battery/energy system which attaches to the rear of your average bike, and is charged by – you guessed it – riding the bike. The specific concept is not itself new, however Siva Cycle has spent two years developing and improving the prototype: and it has payed off. 

 

The Atom features an ultra-lightweight design and USB access to any electronic device that you may possess and desire to be charged. The capabilities of the Atom include a very regulated feed of power, depending on how fast the rider is pedaling. If pedaling at least 3 mph the generator feeds about .75W, and caps delivering 4.5 W. The Atom is water resistant, less than 300 grams, and includes a rechargeable battery source to be attached directly to the charging mechanism in case you need a battery pack on the go.

Siva Cycle is not being selfish with their success either: for every ten Atoms purchased, one is being donated to a country or community in need of some form of electricity. In addition to this fact, the Atom is extremely cheap: once available for commercial sales it is selling for a mere $85. The mechanical engineers of the development team put strong emphasis on the reliability of the design, and show their confidence now through donation and research. The Atom will available to purchase within the next 6 months, and we will have just one more energy option and another example of the environment-friendly, innovative piece of equipment that our generation of engineers are capable of creating. 

 

Photos courtesy of Siva Cycle Co.

Sources:

http://www.kickstarter.com/projects/332999904/the-siva-cycle-atom

http://venturebeat.com/2013/04/23/pedal-powered-generator-lets-you-charge-your-phone-while-you-ride/

The HR-MP20: The Wind Turbine Ascension Robot

 

Robots have long been depicted as having the potential to take over human tasks and jobs. As time continues to progress this concept is becoming more and more a reality. Helical Robotics has just developed a robot designed to conduct maintenance and visual inspection of wind turbines. Because of the immense height of the turbines in wind farms – often ranging from 300 feet with 200 foot blades – visual inspection for defects is difficult to do without scaling the turbine itself. That is where Helical’s new HR-MP20 wireless climbing robot comes in. At a lightweight forty-two pounds, the MP20 is efficient and easy to transport. However, the problem with wind turbine maintenance robots in the past has been the occurrence of powerful gusts of wind can dislodge or blow a robot off the turbine. Helical has approached this problem by using high powered magnets to form something similar to treads for wheels on the MP20, rather than the typical design of vacuum suction for attachment. While the strength and efficiency of these magnets limit this design to metal surfaced turbines, its benefit is in larger payload capacity it can carry. The magnetic adhesion system prevents the robot from touching the work surface at all, it can work on any surface plane greater than seven inches in diameter. The MP20 is fully configurable allowing users to integrate cameras, sensors, or any other appropriate type of equipment into the robot. The HR-MP20 runs just under $20,000.00, but having a small and portable device doing the dangerous ascension work rather than life-insured employee is potentially much more cost-effective. The idea that we will be controlled by robots is still distant, but mechanized task-oriented robots are increasingly being integrated into our daily lives for assistance, leisure, and even convenience. 

 

 

Sources:

http://www.helicalrobotics.com/HR-MP20

http://robotics.tmcnet.com//topics/robotics/articles/334705-hr-mp20-helicals-wireless-climbing-robot.htm

iLimb Ultra: Phone Controlled Prosthetic

Prosthetic limbs are no new innovation, from the crude – peg leg and hooks – dating back centuries, to mechanically controlled limbs and digits. However, a company called Touch Bionics has developed a technologically innovative bionic limb known as the iLimb Ultra. This prosthetic hand has a variety of unique features including motors contained in each digit of the hand,  full thumb rotation, and muscle controlled movements, although these movements admittedly take a long time for the user to develop. The most extraordinary feature on this prosthetic hand however, the piece that makes this hand noteworthy is that Touch Bionics has made the iLimb Ultra be controllable, programmable, and repairable via iPhone and iTouch applications. The iPhone app has twenty-four unique hand positions that are programmable for the user’s convenience, all one has to do is select a specific hand position and the iLimb Ultra will snap to that position and will help the user to learn and manipulate the muscles necessary to achieve that position on their own. As a bonus, there is also a diagnostic toolkit that comes included with the Ultra, so the user can repair any kinks in their hand on the spot. Amputees interested in possessing this feat of engineering should come cautioned however: the iLimb Ultra costs upward of $60,000.00, only supported by Apple (to the chagrin of Android users), and is not at all waterproof. Yet for those who can afford this limb installment, there has been support to such a degree that developers have started to worry about individuals electing for amputation just to attain an “upgrade” to their own flesh. As exciting developments such as the iLimb continue to be made in fields such as this, will additional caution be necessary for such persons hoping just to become more than human? We will see. For now, amputees with the necessary resources have one more option for prosthetic limbs.