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HOW A TURBOCHARGER WORKS


A significant difference between a turbocharged diesel engine and a traditional

naturally aspirated gasoline engine is the air entering a diesel engine is compressed

before the fuel is injected. This is where the turbo charger is critical to the power output and efficiency

of the diesel engine.


It is the job of the turbo charger to compress more air flowing into the engine’s

cylinder. When air is compressed the oxygen molecules are packed closer together. This

increase in air means that more fuel can be added for the same size naturally aspirated

engine. This then generates increased mechanical power and overall efficiency

improvement of the combustion process. Therefore, the engine size can be reduced for a

turbocharged engine leading to better packaging, weight saving benefits and overall

improved fuel economy.


How Does a Turbocharger Work?


A turbo charger is made up of two main sections: the turbine and the compressor. The

turbine consists of the turbine wheel (1) and the turbine housing (2). It is the job of

the turbine housing to guide the exhaust gas (3) into the turbine wheel. The energy from

the exhaust gas turns the turbine wheel, and the gas then exits the turbine housing

through an exhaust outlet area (4).


The compressor also consists of two parts: the compressor wheel (5) and the

compressor housing (6). The compressor’s mode of action is opposite that of the

turbine. The compressor wheel is attached to the turbine by a forged steel shaft (7),

and as the turbine turns the compressor wheel, the high-velocity spinning draws in air

and compresses it. The compressor housing then converts the high-velocity, low-pressure

air stream into a high-pressure, low-velocity air stream through a process called

diffusion. The compressed air (8) is pushed into the engine, allowing the engine to burn

more fuel to produce more power.


Better Fuel Efficiency Through a Better Oil Pump


As the market and government regulations push automakers to improve emissions and

fuel consumption, they are evaluating all opportunities in the engine system to reduce

losses. The oil pump is one

important component that consumes engine power as it protects engine components from

frictional wear and overheating by delivering oil at the correct pressures.


Fixed-displacement oil pumps currently circulate oil in most automobiles. Designers

typically oversize the pumps to handle the harshest engine operating conditions. Most of

the time, they consume more power and deliver significantly higher oil pressure than

needed. They contain pressure-relief valves as a crude, cost-effective, and reliable way

to avoid excessively high oil pressures. But these designs are inefficient, losing

significant amounts of energy at high oil flows typical in internal-combustion engines.


Providing Customized Oil Flow


Variable-displacement oil pumps help to minimize energy losses. Their active control

matches the oil flow and pressure the engine needs, eliminating excess oil flow,

significantly reducing the parasitic load on the engine crankshaft, and ultimately

saving fuel.


In variable displacement pumps, changing the displacement volume controls the flow

rate. Vane-pump designs have hydraulic and electrical controls and actuators that move

the pump housing and vary the eccentricity of the rotor. Electronic control signals and

solenoid control valves vary the pressure set points as operating conditions dictate.


Automobile OEMs adopted these types of pumps in 2011, applying them in engines for

high-end vehicles in Europe. Although research has evaluated the fuel-economy benefits

of reduced oil flow from a torque-reduction perspective, the industry lacked information

about its control, use, and thermal interactions with other engine systems.


As part of an industry- and university-consortium project partially funded by the UK

Technology Strategy Board, researchers at the University of Bath, Bath, UK, and Ford

Motor Company, Detroit, MI, thermally tested variable-displacement oil pumps to gain

insight about performance and oil pumping speed. The group evaluated vane and rotor pump

designs in an active 2.4-L diesel engine on an engine stand at many different operating

conditions and found that fuel economy benefits warrant the pump expense.


Understanding Oil Coolers


When engine output rises beyond a certain threshold per liter of displacement, an

oil cooler becomes more

important, critical even. There is a lot to the selection and installation of an oil

cooler, so to find out more, we caught up with Zac Beals, a technical sales

representative with Setrab USA, a Swedish company that specializes in a full range of

heat exchangers and radiators for OEM applications, and oil cooling for motorsport.

There are right and wrong ways to add an oil-cooling system, based on application and a

number of other factors, but there are two key tenets to follow when adding an oil-

cooling system: get expert help and don’t skimp on materials.


“Oil is the only thing preventing metal-to-metal contact, and any high-performance

engine is designed with its own optimal oil temperature range based on how much work the

oil is doing in that system,” Beals said. “The demands on the oil in a high-revving

turbocharged four-cylinder are different from the demands on the oil in a naturally-

aspirated V-8, and the differences only get more specific from there.


“What we do know for sure is that most generally, temperatures in excess of a

normal operating range will break down the ability of the oil to do its traditional

lubrication job,” Beals added. “A rule of thumb is that every 20 degrees in excess

heat will half the life of the oil. This has a related effect on every internal

component the oil touches.”


An oil-cooling system consists of the fittings and hoses to get the oil out of the

engine to the cooler itself and back into the engine. It seems pretty simple, right? Not

exactly.


Fan Clutch


Belt driven fan clutches have been used as standard equipment on many vehicles for

decades. However, the automotive clutch market is diminishing as other more efficient

options are hitting the market and being demanded by consumers. Fan Clutches are ‘fluid

’ coupling devices that provide air flow through the radiator by using the water pump

shaft to power the fan blade. When the pump is cool or at normal operating temperature,

the fan clutch will

partially disengage. However, due to only partially disengaging they will always be

spinning at about 30% of the water pump speed at all times. When compared to an electric

fan, fan clutches are quite inefficient.


Cylinder Head



In simple terms, the cylinder head is just a casting that tops off the engine block, holds the

valves and forms the combustion chambers. Working in combination with the camshaft(s),

induction and exhaust systems, the head determines how the engine breathes, the engine’

s power curve and personality. The “right” cylinder head will deliver peak power in

the preferred rpm range, providing good throttle response and producing the kind of

torque and horsepower numbers your customers demand.






Using the wrong head can ruin your reputation.


Some people pick a set of cylinder heads based on previous experience,

reputation or simply brand recognition. Some look for highest airflow claims while

others take the price path. The best selection process, of course, is rarely so simple.


Car Engines



The core of the engine is the cylinder, with the piston moving up and down inside

the cylinder. Single cylinder engines are typical of most lawn mowers, but usually cars

have more than one cylinder (four, six and eight cylinders are common). In a multi-

cylinder engine, the cylinders usually are arranged in one of three ways: inline, V or

flat (also known as horizontally opposed or boxer), as shown in the figures to the left.


So that inline four we mentioned at the beginning is an engine with four cylinders

arranged in a line. Different configurations have different advantages and disadvantages

in terms of smoothness, manufacturing cost and shape characteristics. These advantages

and disadvantages make them more suitable for certain vehicles.


Let's look at some key engine parts

in more detail.


Spark plug


The spark plug supplies the spark that ignites the air/fuel mixture so that

combustion can occur. The spark must happen at just the right moment for things to work

properly.


Valves


The intake and exhaust valves open at the proper time to let in air and fuel and to

let out exhaust. Note that both valves are closed during compression and combustion so

that the combustion chamber is sealed.


Piston


A piston is a cylindrical piece of metal that moves up and down inside the cylinder.


Piston Rings


Piston rings provide a sliding seal between the outer edge of the piston and the

inner edge of the cylinder.


What Is A Brake Booster And What Does It Do?


The brake booster is

a device used to amplify the force applied on the

brake pedal when transferring that force to the brake master cylinder. Brake systems

that have them are often called “power brakes.”


The brake booster is used on almost all cars with hydraulic brakes — you won’t see

them on vehicles that use pressurized air systems as their primary brake circuits.


BRAKE ROTORS/BRAKE DISCS


What they are: Sometimes called brake rotors, sometimes called discs, this brake

part is one of the main components of disc brakes. When brake pads press against the

disc/rotor on each side, it causes the system to slow down or stop.


How long they last: As with all brake

parts
, it can vary, but brake rotors/discs tend to last anywhere from 30,000 to

70,000 miles. You can also extend their life with brake resurfacing. They should be

inspected every 12,000 miles, however.


When to replace: The surface is where this brake part wears down. Over time, grooves

or ridges can develop where the brake pads press down on them. If the brake pads

can't maintain an even contact surface, you may experience grinding, meaning

it's time to resurface or replace the rotors or discs. It's recommended to

replace brake rotors/discs in pairs.


Excessive Steering Play / Loose Steering


If your steering rack

and pinion wear out, the steering will feel loose. You will also notice that the

car wanders at high speed, and it is hard to keep it in the lane.


Also, every road imperfection causes your car to easily move left to the right

instead of staying in a straight line.


You may also notice that steering is harder at lower speeds. On top of all these

symptoms, you will also notice that the wheels don't return to a straight position

after turning.
  • Létrehozva: 21-11-03
  • Utolsó belépés: 21-11-03

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