CAR BASICS FOR BUDDING AUTOMOBILE ENGINEERS

By- Utkarsh Kushwah UPES

Welcome to Car Basics! Here you will embark on great adventure i.e. learning all about the basics of the major system that power your car.

Introduction

Engine Fuel System Exhaust System Cooling System Drivetrain Suspension Electrical System Body Brakes Heat /AC Oil

The information in this report will give you the most fundamental working knowledge about your’s car

There are three main components that make up a combustion engine:

1. Piston2. Crankshaft3. Valvetrain

These three components work in concert to pump air and fuel and turn your wheel. Let’s look at each on in a little more detail.

Your Car’s Engine

Your average car engine will have 4,6 or 8 pistons. You can think of piston as similar to “plungers” moving up and down within their cylinders. On the top side of the piston is the combustion chamber, where fuel and air are mixed together before being ignited.

On the other side of the piston is the crankcase, which is full of oil. Your air and fuel are kept separate from the oil by “O-Ring” style rubber seals

1.Piston

2. Crankshaft The crankshaft is connected to piston by a rod. As the piston moves up and down, the crankshaft rotates and converts the up and the down motion into rotatory motion. In other words, it helps turn the wheels.

3. Valvetrain The valvetrain is made up of valves, rocker arms, pushrods, lifters and the cam shaft. The job of the valvetrain is to let the air and fuel in and out of the engine at the appropriate time. This is accomplished by synchronizing the cam shaft to the crankshaft with a belt or a chain.

The average car today uses what is known as a “4-stroke” or “4 cycle” engine. What this means is that there are four separate events that happen in your engine as it runs:1. Intake stroke2. Compression stroke3. Power stroke4. Exhaust stroke

How it all works

1. Intake stroke

An intake valve is opened by the camshaft, and the piston moves down inside the cylinder creating a vacuum which sucks air and fuel into the combustion chamber.

2. Compression stroke The intake valve closes as the piston moves up the cylinder. This creates a seal that allows the air and fuel to be compressed.

3. Power stroke As the piston nears the top of the cylinder, the spark plug fires and ignites the compressed air and fuel. The force of ignition drives the piston back down into the cylinder again, turning the crankshaft..

4. Exhaust stroke

Once the piston reaches the bottom of the cylinder again, the exhaust valves opens. Leftover air and gas are sent out to the exhaust system.

If any part of your fuel system breaks down, your engine will not. Therefore it is very important to keep your fuel system well-maintained and address any problem that come up soon as possible.

Let’s look at the parts:1. Fuel tank2. Fuel pump3. Fuel filter4. Fuel injectors (newer cars)5. Carbonator (older cars)

Your Car’s Fuel System

1. Fuel Tank Pretty self-explanatory! The fuel tank is where your car’s fuel is stored. Inside the tank is a sending unit which tells your gas gauge how much fuel is left in the tank.

2. Fuel Pump On newer model cars, the fuel pump is usually installed inside the fuel tank. On older model cars, the fuel pump may be attached to the engine or on the frame rail between the tank and engine.

3. Fuel Filter Fuel filters may be located before or after the fuel pump (and in some cars, there are two fuel filters – one before the pump, and one after). Intake valves tend to get clogged and fuel filters serve to clean this build up out of the gasoline.

4. Fuel Injectors Fuel injection is used in the majority foreign and domestic cars produced after 1986. The fuel injector is a small, electric valve. The opening and closing of this valve is controlled by a computer.

5. Carburetor On older model cars, a carburetor is used to help mix air and fuel. It’s a very inefficient process , and carburetors are notorious for breaking down. This is why most manufactures switched to fuel injection.

Your exhaust system carries away the gasses created by engine combustion. The whole system consist of five components:

1. Exhausted Manifold2. Oxygen Sensor3. Catalytic Converter4. Muffler5. Exhaust Pipe

Your Car’s Exhaust System

1. Exhaust Manifold The exhaust manifold attaches to the cylinder head, taking the exhaust from each piston, and routing it through one pipe.

2. Oxygen Sensor A component of fuel-injection system, the oxygen sensor monitors the level of oxygen present in the exhaust and makes adjustment to fuel input in order to maximize fuel economy. An oxygen sensor is usually mounted near the exhaust manifold.

3.Catalytic Converter The catalytic converter acts somewhat like a filter in that it’s job is to convert harmful byproducts of the process into less harmful ones. Namely, carbon monoxide and hydrocarbons are converted to water vapor and carbon dioxide. Your catalytic converter should be located between your exhaust manifold and muffler.

4.Muffler The muffler “muffles” the sound of your engine’s combustion and exhaust process. Sound is reduced by “bouncing” the exhaust against internal baffles to reduce its energy.

5.Exhaust Pipe Once your gas has turned to vapor within the exhaust system, it is carried out of your car through the exhaust pipe.

As you can imagine, your car’s engine gets super hot while running. Normal operating temperature for the average fuel burning engine is around 2,000 degrees Fahrenheit, but temperatures may go up as high as 4,000 degrees F. during the combustion process.

A cooling system is necessary for a couple of reason:1. To prevent temperature high enough to melt engine parts.2. To stabilize engine temperature at the most efficient level

regardless of environmental conditions.3. While some heat is carried away by the exhaust system. It’s

not enough to protect the pistons and cylinders.

Your Car’s Engine-Cooling System

Most automobiles use what is known as a “liquid-cooling” system. In other words, a liquid ‘coolant’ is circulated to absorb and carry away heat from the engine.

This liquid is then sent o the radiator, where it is “re-cooled” again and sent back out for another pass through the engine.

Let’s look at the parts involved in the cooling system:

1. Hoses

2. Fan Belt

3. Radiator

4. Water Pump

1. Hoses Hoses are used to carry the liquid coolant.

2. Fan Belt A Fan belt is used to drive the water pump, which circulates the coolant through the system.

3. Radiator The radiator cools your coolant.

4. Water Pump The water pump, which is driven by your engine via fan belt, is responsible for pushing the coolant to circulate

The drive train (also sometimes referred to as the ‘power point’) serves two functions:1. Drive power from the engine to the drive wheel.2. Vary the amount of torque.

We use the expression “drive wheel” to refer to the actual “driven wheels” of a vehicle. For instance, an automobile with 2-wheel drive is designed to power 2 drive wheels (either the two front wheels or the back wheels), while the remaining wheels on the vehicle roll out but do not actually power the car forward.

There are two sets of gears in the drive train:3. Transmission4. Differential

Your car’s Drive Train

Transmission The transmission is used to adjust gear ratio. This is similar to (but more complex than) the gear-switching of a bicycle. Automotive transmission require multiple ratio gearboxes to maintain the same engine RPM’s at different speeds.

Differential The differential is used to help the wheels turn at different speeds.

Now , we can break the transmission down even further because there are 2 types of transmission you are probably familiar with:

1.. Manual

2. Automatic.

Manual Transmission Manual transmission usually have 4 or 5 speeds. Most use manual clutches, but there are a few models out there that actually use an electric clutch with a manual stick shift. Manual transmissions require the driver to shift the gears.

Automatic Transmissions Automatic transmissions typically use 3 “forward” gears. Each gear is intended to balance speed and torque for the current driving conditions (starting, acceleration, driving up hill, etc). In automatic transmissions, though, is that the gear-shifting process is controlled by oil pressure. A “shift valve”, controlled by oil pressure, is employed to shift the gears to meet the immediate driving conditions.

Your AXLE may be located at the either the front or the rear depending on whether you have front or rear wheel drive. Power from the engine is delivered to the axle by DRIVESHAFT.

Suspension in this case refers to the front and rear springs that suspend your car’s weight. Today’s suspension system may be constructed from a variety of spring types, shapes and sizes, such as:

Leaf springsCoil springsAir springsTorsion springs

Also include in the suspension system: shocks, struts and sway bars.

Your Car’s Suspension System

The electrical system in today’s cars are complex, and there are dozens of things that can go wrong at any times with the major devices as well as auxiliary devices such as radios, chargers, defrosters, power windows and so on.

The Big Three things that you need to pay attention to are:1. The Battery2. The Starter Motor3. The Alternator

Your Car’s Electrical System

The Battery Your battery stores power to start your car, as well as run all the secondary devices like radios and clocks.

The starter Motor The starter motor is a DC solenoid used to start the car’s engine.

The Alternator The alternator manages current to keep your car charged while running (it is powered by the engine), and to restore charge to the battery.

In old days, car body’s were almost entirely metal. These days, however, most car bodies are composite of fiberglass and plastic around a metal frame.

Common body problem may include:

1. Rust – In this case, we’re talking about rust from the inside out. This is a bigger problem with older model cars.

2. Accidents – Repairs can get pricey on newer model cars due to their construction. A metal bumper, for example, can be ‘banged’ back into some cases. Plastic bumpers, however, usually have to be replaced in full.

3. Paint – UV rays from the sun can damage paint over time. Scratches and dings from rocks, hail or other debris can create chips in the paint leading to further deterioration.

Your Car’s Body

If you have a newer model car or truck, it is likely that you have disc brakes on all braking wheels, rather than drums. Older models braking system typically employ disc brakes on the front wheels and drum brakes on the back wheels.

Why disk brakes? Disc brakes are lighter and perform better than drums in terms of wear and tear. This is because the disc brakes are gripped on either side by the brake pads, similar to the brakes on a cycle. The wear form the heat and friction is distributed evenly.

Your Car’s Brakes System

A standard brake system consist of 4 main components:

1.. Disc and or drums and rotors2. Friction pads3. Master cylinder and brake cylinders4. Brake Fluid The master cylinder connects to your brake pedal via a “push rod”. This push rod is then connected to each brakes cylinder by steel brake lines and the rubber hoses that carry the hydraulic brake fluid. Pressure applied to the brake pedal activates the master cylinder pistons which pump brake fluid through the system.

The first thing to note is that your heating and AC system is designed to:1. Add heat to the inside environment, or2. Remove heat from the inside environment

In other words, the cooling of your AC is not achieved by “creating cold”, but by removing heat and moisture from the air until the desired temperature is achieved.

Your Car’s Heat and AC

Your Car’s heating and AC system consist of the following:1. Heater core or ‘secondary’ radiator2. Compressor3. Evaporator4. Condenser5. Fan6. Hoses 7. Liquid refrigerant (Freon, usually R-12 or R-134)

In order to heat your car, the system circulates air around the heater core then return it back into the interior of the vehicle. Simple enough, right?The AC system is more elaborate. It starts with the evaporator, which receives the air pulled from the interior of the car via a fan. Meanwhile, your compressor is moving refrigerant through a condenser and back to the evaporator.

In other words, your AC removes heat from the air by removing the water vapor it on a continual basis as it circulates through the system and back into car.

Oil lubricates the moving parts of your engine, protecting them from the wear of friction and high temperatures.

What is important here , though, is nit any of the parts of the system but itself. The biggest thing you can do to extend the life of your vehicle is to have the oil changed on regular basis. Most manufactures recommend you get an oil changed every 2 to 3 months or every 2,000 to 3,000 miles.

It is vitally important that you use the correct grade and viscosity of oil for your driving conditions. Very cold driving conditions require a thinner viscosity ( the thinner the oil, the faster it heats up) while very hot conditions may require multi-grade or higher viscosity oil

Your Car’s Oil

Car Basics for Beginners. Everything You’ve Always Wanted to Ask Your Mechanic. Retrieved January 26, 2010, from http://automobile.for-beginners-only.com

Reference

Prepared by:

Utkarsh Kushwah B-Tech (Automotive Design) 2009-13 University of Petroleum & Energy Studies