Automotive Services Rotary spark-ignition engine & components

Rotary spark-ignition engine & components :
  Basic principles of the rotary engine
  Basic components of the rotary engine
   Rotary engine cycle
  Rotary/piston engine comparison
  Rotary engine power pulses
  Renesis rotary engine

Basic principles of the rotary engine

The rotary engine is not as common as the 4-stroke or 2-stroke engine but its basic principle is well accepted. It operates very differently from a reciprocating engine.
A piston-engine is called reciprocating because the pistons move back and forth over the same path. This reciprocating motion changes into rotary motion at the crankshaft.
A rotary engine has a rotor, not a piston, and it’s called rotary because the rotor has a planetary motion. It does not reciprocate.
The rotor is roughly triangular in shape and it turns inside a housing which is a particular geometric shape called an epitrochoid curve.
Because it spins, rather than moves up and down, engine operation is said to be very smooth and vibration free.
Let’s look at basic principles of the rotary engine.
The rotary engine does look different but it is still an internal combustion engine, so let’s find the 5 key events common to all internal combustion engines.
Intake occurs when air-fuel mixture enters the working chamber at the inlet port.
The turning rotor then carries it around to the spark plugs. Along the way, the volume of the working chamber decreases, and compresses the mixture.
The mixture is ignited and combustion occurs. Expanding gases produce a power pulse, driving the rotor onward.
When the exhaust port is uncovered, exhaust occurs as the rotor sweeps burned gases out of the housing.
Which brings it all back to the beginning, ready to run a new cycle.

Motive Power Types : Engine characteristics

Engine characteristics :

• Engine output
• Power range

Engine output

Engine output refers to the torque and power produced by an engine. The purpose of the engine is to provide the energy to drive the vehicle. Energy released by burning fuel and air in the cylinders produces a turning force or torque which drives the wheels.

Motive Power Types : Compression-ignition engine components

Compression-ignition engine components :

• Basic diesel engine components
• Diesel engine passages 
• Diesel fuel delivery
• Direct injection
•  Diesel valves & components
•  Diesel scavenging
• Crankshaft rotation 
• Diesel crankshaft
• Diesel engine pistons

Basic diesel engine components

4-stroke and 2-stroke diesel engines both use the principles of internal combustion, so many of their components have similar designs.
Diesel engine components are exposed to higher operating temperatures, pressures and forces than gasoline engines of similar size. Their compression ratios are higher, and they are often designed to out-last gasoline engines. Their engine parts are usually heavier or more rugged than those of similar output gasoline engines.
Diesel blocks are usually made of cast iron, and heavier than in a gasoline engine. The skirt of the block usually extends below the centreline of the crankshaft. This adds strength and rigidity.
Machined into it are the cylinders which are usually in the form of detachable sleeves or liners.
It is sealed at one end by a deep-section piece of metal or alloy called a cylinder head, which houses the valves and injectors.
Most cylinder heads in diesel engines are cast iron. Depending on the engine design, single or multiple heads can be used.
Multiple heads avoid large castings that, apart from being heavy, are liable to distortion.

Motive Power Types : Compression-ignition engines

Compression-ignition engines:
  Basic 4-stroke diesel principles
  4-stroke diesel engine cycle
   Basic 2-stroke diesel principles
  2-stroke diesel engine cycle
   Three phases of combustion

Basic 4-stroke diesel principles

This is one cylinder of a 4-stroke diesel engine. This model uses what is called direct injection. It is an internal combustion engine, with the 5 events common to all internal combustion engines. Let’s see how they happen in diesel engines.
Unlike the gasoline engine, air alone enters the cylinder on the intake stroke.
Compression, forcing the air into a small volume. This compression heats the air. At the end of this stroke, diesel engine fuel is injected into the combustion chamber.
Ignition, burning the mixture. It is just the heat of the compressed air that ignites the fuel. That’s why diesels are called compression ignition engines.
Power, where energy released from combustion generates the force to turn the crankshaft.
And Exhaust, removing leftover gases.
This brings the system back to where it began, ready for another cycle

Motive Power Types : Hybrid drive systems,Hybrid vehicle systems,Series-parallel hybrid systems ,Hybrid system components , Hybrid vehicle driving

Hybrid drive systems: 
  Hybrid vehicle systems
  Series-parallel hybrid systems 
  Hybrid system components
  Hybrid vehicle driving 

Hybrid vehicle systems

There are three hybrid systems,

1. series,
2. parallel, and
3. series-parallel.

In series hybrid an internal combustion engine drives an alternator. The current produced by the alternator is used to power an electric motor that drives the wheels. It is called a series hybrid system because the power flows from the engine to the motor, before flowing to the wheels. In principle, a small-output engine drives a generator and supplies electricity to drive the electric motor and charge the battery.
A parallel hybrid system uses an efficient internal combustion engine to drive a transmission conventionally, but it also drives a flywheel mounted motor/generator, which charges a storage battery when the engine is turning. It is called a parallel hybrid system because the power flows to the wheels in “parallel”. This means that energy from the battery can be released, when needed, and delivered to the motor/generator to assist the engine in driving the transmission. Although it has a simple structure, the parallel hybrid arrangement cannot drive the wheels from the electric motor while simultaneously charging the battery due to the fact that the system only has one motor.
The series-parallel hybrid system is more sophisticated and uses both the engine and an electric motor to drive the transmission. The system combines the series hybrid system with the parallel hybrid system in order to maximize the benefits of both systems.

Motive Power Types : Hybrid drive systems, Service hybrid electric vehicles – safely

Service hybrid electric vehicles – safely!

With record high prices for crude oil, and at the pump, consumers are placing record numbers of orders for gas saving light-duty hybrid electric vehicles (HEVs). But how prepared are shops when it comes to servicing these?
Technician A says general automotive knowledge and skill may be sufficient when performing routine maintenance on hybrid electric vehicles.
Technician B says that specialized training is needed when performing service on high voltage systems on hybrid electric vehicles.
Who is right?

1. A only
2. B only
3. both A and B
4. neither A nor B

Of course, the correct answer is C. As with any vehicle, hybrids need routine LOF service, tire rotation, alignment, brakes etc. On the other hand, servicing high voltage battery packs, hybrid drive systems and motor electronics introduces new challenges for technicians.
In this article, we’ll discuss more need-to-know about hybrid systems and components in HEVs from Toyota, Honda, General Motors and Ford. The general outline presented here does not replace authorized HEV factory training, but it will help you get started.

The Nature of Hybrids

For improved fuel economy and emissions, hybrids use specially designed tires and wheels, “slippery” body styles, regenerative braking, engine start/stop features, etc. Hybrid gasoline engines (ICEs) feature electronic throttle controls, variable valve timing, lean burn combustion designs, and more, making them more complex, and challenging! Despite the sophisticated nature of hybrid systems, technicians should be qualified for routine hybrid vehicle service. Don’t expect to see belts and pulleys under the hood, however, as space is often dominated by hybrid drive and electrical components.
Scan tools are a fact of life in today’s service bay, helping us “see” into the world of invisible electronics and diagnose problems. “The scan tool will remain the mainstay of the technician’s arsenal, for analyzing and diagnosing a hybrid and [its] electric power system.”
You’ll not only be accessing familiar engine data—Engine RPM, MAP/ MAF, injector pulse width, etc.—but also comparable data about the electric drive components: Encoder Signal, Current Sensor, Pedal Position, Commanded Current, Phase Faults, Slip %, and more. To interpret such arcane data, specialized HEV training is a must, and numerous training providers now offer it.

Motive Power Types : Hybrid drive systems, Electric vehicle models

Hybrid electric vehicle models

Rising gas prices have generated a wave of public interest and publicity about gas-saving hybrid electric vehicles (HEVs), and for good reason: Hybrids make good sense. Hybrid vehicles use “two or more energy conversion technologies.”
Often, an internal combustion or “heat” engine (ICE) using gasoline or diesel fuel develops primary power for traction and driving the on-board generator. Other fuels used include natural gas, propane, ethanol, methanol and dimethyl ether, and other engine types include natural gas and propane powered micro turbines, and hydrogen fuel cells. Hybrid EVs also use a source of stored secondary backup power, such as advanced batteries, ultracapacitors, or even flywheels, to augment the primary power source. Under prescribed driving conditions, the secondary source will assist or even take over propulsion of the vehicle. In some hybrid designs, secondary power is used exclusively at low speeds or in urban traffic environments to reduce pollution and save fuel. While a variety of primary and secondary power sources may be employed (including plug-in power), the ultimate focus of R&D seems to be on developing zero emission hydrogen fuel cells for hybrid EVs. Besides the basic series and parallel hybrid powertrain systems described earlier, hybrids are often configured to operate in a variety of cross configurations.
To give you an idea of the extent of HEV activity going on, listed below are U.S. market-released hybrid automobiles, and some of those (hopefully) becoming available soon. Note that specifications are drawn from a variety of data sources; because the HEV landscape changes almost daily, the information included is subject to change. For the most current data, it’s best to check with the OEs (See the sidebar listing online resources.)

Motive Power Types : Hybrid drive systems, Hybrid electric vehicles

So, what’s a hybrid? A “hybrid” is normally an offspring of two dissimilar plants or animals, but the US Dept. of Energy defines a hybrid as a type of electric vehicle (HEV) which “…combines two or more energy conversion technologies (e.g., heat engines, fuel cells, generators, or motors) with one or more energy storage technologies (e.g., fuel, batteries, ultracapacitors, or flywheels).” Hybrid power is hardly new; it’s been around for years. Pre-nuclear era submarines are diesel-electric hybrids; so are most of our railroad locomotives, many industrial machines, etc. From an automotive perspective, hybrids are still rare, but that’s changing. Let’s look closer at HEVs—what they are, where they are, and why they’re showing up on our highways.

Motive Power Types : Hybrid drive systems, Battery electric vehicles

Battery electric vehicles

Electric vehicles on the road?… You’ve got to be kidding!
Such is the reaction of most people who envision undersized, limited-range vehicles, with no place to charge them up. Despite that reputation, electric vehicle (EV) technology has progressed steadily, making EVs popular once more. But according to the U.S Department of Energy, owners of electric vehicles are faced with a lack of skilled EV service technicians. Interested in knowing more about EVS?…

Motive Power Types : Hybrid drive systems

Hybrid drive systems

Hybrid vehicles

A hybrid car or hybrid electric vehicle is a vehicle which relies not only on batteries but also on an internal combustion engine which drives a generator to provide the electricity and may also drive the wheels directly.
Prior to its modern usage to mean hybrid propulsion, the word hybrid was used in the United States to mean a vehicle of mixed national origin; generally, a European car fitted with American mechanical components. This is falling out of use as the newer meaning gains more currency.

Motive Power Types : Alternative engine cycles

Alternative engine cycles


Alternative engine cycles

The Miller Cycle engine and the Atkinson Cycle engine are both variations on the traditional four-stroke spark ignition engine. These engines operate more efficiently, but produce lower power outputs.
In a conventional 4-stroke cycle, the compression stroke and the power, or expansion stroke, are symmetrical. The compression and expansion ratios are calculated by adding the volume of each whole stroke to the volume of the combustion chamber and then dividing that figure by the combustion chamber volume. In a conventional 4-stroke engine, the stroke in each cylinder is the same length so the ratios are the same.
Increasing engine efficiency by extending the stroke and raising the expansion ratio also raises the compression ratio. There is a limit to how high the compression ratio can be because raising it too much results in premature detonation without ignition.

Motive Power Types : Spark-ignition engine components

Spark-ignition engine components:
Basic engine components
4 & 2-stroke engine differences
Engine cams & camshaft
Engine power transfer
2-stroke power transfer
Scavenging
Counter weights
Piston components
Alloys

Basic engine components

This section looks at major components of the 4-stroke and 2-stroke petrol engine. Because they operate on similar principles, many of their components are similar too.
For example, their engine blocks both operate under working conditions of very high pressures and temperatures, and new designs and materials to make them work more efficiently are always being tested.
Many vehicles still use cast iron, but some have aluminium alloy blocks. The main gain is a saving in weight. Aluminium alloys can be made as strong as cast iron, but they are lighter. This is also true for cylinder heads.
Combustion chambers in the cylinder head come in many different designs.
To help hold in the extreme heat and pressure of combustion a seal is made between the block and cylinder head by a head gasket.
The 4-stroke petrol engine has other passages cast into the head to carry oil for lubrication and coolant for cooling.

Motive Power Types : 2-stroke spark-ignition engines

2-stroke spark-ignition engines:
Basic 2-stroke principles
2-stroke engine power stroke
2-stroke engine cycle
2-stroke intake system
2-stroke cycle
 

Basic 2-stroke principles

The 2-stroke petrol engine is different from the 4-stroke petrol engine. In a 2-stroke engine the inlet and exhaust ports are open and closed by the movement of the piston. But it is still an internal combustion engine and has the 5 events common to all such engines.
Intake occurs when the air-fuel mixture enters the crankcase. It is then transferred from the crankcase to above the piston.
Compression, forcing the mixture into a small volume.
Ignition when the spark from the spark plug ignites the mixture, and it burns.
Power, where energy released by combustion generates the force that turns the crankshaft.
And Exhaust, removing leftover gases.
As in all internal combustion engines, these 5 events must occur, but not always in the same way.
The whole process is a cycle. A new mixture enters and is ignited. Combustion occurs. Expanding gases drive the piston down and turn the crankshaft which pushes the piston back up the cylinder.

Motive Power Types : 4-stroke spark-ignition engines

4-stroke spark-ignition engines :
   Basic 4-stroke principles
   4-stroke engine cycle

Basic 4-stroke principles

This is a cylinder for a 4-stroke Petrol/Gasoline engine. The first step is to get the air-fuel mixture into the chamber. Mixture enters through an inlet port that is opened and closed by an inlet valve. This is called Intake.
Next is compression. The piston compresses the air-fuel mixture into a smaller volume.
A spark across the electrodes of a spark plug ignites it, and it burns. This burning is called combustion.
The burning gases expand rapidly, and push the piston down the cylinder until it reaches bottom dead center.
The reciprocating action of the piston turns into the rotary motion of the crankshaft.
The crankshaft forces the piston back up the cylinder, pushing leftover gases out past an exhaust valve. And everything is back where it started, ready to repeat the whole process.

Motive Power Types : Motive power fundamental principles

Motive power fundamental principles :
  Pressure & temperature
  Pressure & volume 
  Temperature & energy
  Understanding power and torque

Pressure & temperature

The pressure and temperature of a gas are linked. As pressure goes up and down, so does temperature.
Take a container that has a fixed amount of gas. A plunger seals one end of the container.
A pressure gauge is attached, and a thermometer.
Pushing in the plunger increases gas pressure. It forces the gas molecules into a smaller space.
As a result, they move faster and make more impacts.
This causes the gas to heat up.
And the overall temperature of the gas rises too. An increase in pressure produces a rise in temperature.
Pulling out the plunger reduces gas pressure. It gives the molecules more room to move. They make fewer impacts.