‘Understand vehicle security, environmental control and passenger protection systems’
I will learn that there are many advantages in the modern central door locking system. I will be learning the electrical wiring of a typical modern car, and adding illustrations to explain the various components. I will be explaining the operating principles and identifying the main parts of the environmental control system such as the EGR principles for a Hitachi vehicle mentioning how it works according with the Control Valves and later examining the service and repair procedures for a defective valve. I will include the oxidization process in a catalytic converter with equations showing the addition of oxygen to hydrocarbon when passed over a platinum palladium catalyst. The exhaust produces harmful emissions gases damaging to the atmosphere when released into air. The catalytic converter includes a core of ceramics containing many pores which measure less than 1mm. Most catalytic converters have a good life expectancy but should be checked periodically for internal and external damage.
Assessment Criteria 3.1
The central locking system of a motor car must give access to the driver, it is the means from which the vehicle doors and boot lid are locked and unlocked and the engine is started. The central locking system in a vehicle must give access only to the driver or an authorised person. In past years, only mechanical systems could be operated from the outside with a key or from the inside with a knob. The central locking systems used originally brought about significant improvements in comfort and convenience.
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The electric locking systems are very common today in most vehicles, they work with an infrared or wireless remote control. They can be triggered remotely, for example without contact between key and vehicle. The latest systems use entirely keyless vehicle access. The driver only needs to have a transmitter in their pockets, the doors are then unlocked when the driver touches a door handle which has a built-in contact point.
The central locking system provides locking/unlocking of the entire vehicle from one central exterior point. It is the means in which the vehicle doors and boot lid are locked and unlocked and the engine is started. The locking system is operated with a key or remote control. These systems feature a built-in vacuum reservoir which triggers the locks on all doors when the key is turned in a lock.
The central locking system has the following components:
Door handle/Handle strip, the door handle is the traditional means by which a vehicle is opened and closed from inside or outside. The outside door strip usually houses the door lock. Door strips are frequently used as design elements in modern cars. They can be chrome-plated or paint-finished in the same colour as the vehicle.
Door lock/Actuator, the latching mechanism in a vehicle is installed directly inside the doors. It contains both a latch and an electric motor (actuator) which controls the central locking system. The latch opens or closes the doors, while on the other hand the door lock, locks or unlocks the vehicle. Today, all doors latches are powered by electric drives.
Fuel filler cap, the fuel filler cap will safely seal the fuel tank. Some fuel filler caps have locks, others do not. Fuel filler caps with locks are usually found on vehicle which have either a fuel filler flap which does not lock or no fuel filler flap at all. Fuel filler caps without locks are found on vehicles whose fuel filler flap is locked automatically via the central locking system.
Transponder, the transponder is usually integrated inside the key bow. It is the means by which the electronic immobiliser identifies the correct key is being used. The transponder’s code is read out as the key nears the ignition lock. If the code is correct, the electronic immobiliser will send a start signal ‘enabling’ the engine.
Remote control, the remote controls are being used with increasing frequency in small cars, substituting the functions of a conventional key to all intents and purposes. A signal transmitter sends a signal or a coded order instruction to a receiver inside the vehicle, which usually controls a number of functions. Infrared remote controls have a range of up to 15 m. They depend upon the direct ‘visual’ contact between transmitter and receiver. Today the infrared remote controls are only used rarely as they have been overtaken by other technologies. Wireless remote controls transmit on radio frequencies and have a range of up to approximately 100 m.
Keys, are the basic function and remote control of the locking and unlocking of doors, luggage compartments, fuel filler cap, etc. they are also used to control the interior lighting and electronic immobiliser, the alarm system and the window lifters. The keys are made up of of two units: the milled, toothed key blade and the key bow. The latter is home to an increasing number of electronic functions such as the remote control for the central locking system or the boot lid.
Start/stop system, traditionally a vehicle key was needed to unlock the steering lock and to start the engine. Therefore, the vehicle key was enhanced with the addition of a transponder-based release mechanism for the electronic immobiliser. Today, keyless systems are increasingly being used to start engines. In a keyless system, a transmitter, which usually also houses the controller for the central locking is fitted into a reader in the vehicle and the engine is then started by pressing a button.
Steering lock, the steering locks have been a compulsory requirement set by insurance companies since 1969.They provide protection against stealing. They are the means from which the steering column is unlocked sand the engine is started, either electrically or by conventional mechanical means. My-cardictionary.com (2016)
Diagram 1, An Electrical Wiring Diagram for the Central Locking System of an E36 Coupe vehicle:
Diagram 2, showing a Single Lock, Phase 1, mechanical lock at door and lock signal generation for a BMW vehicle:
The lock button and key mechanically rotate the lock lever which ‘decouples’ the exterior door handle from the latch. When this is rotated the lock lever moves an internal switch ramp to the left closing the lock micro-switch. This provides the lock signal to the GM. When the GM receives the lock signal it activates an internal relay number 1, providing power through the closed single lock contact to the actuator motor. Ground is provided through the module’s closed contact of relay number 3. The vehicle’s actuator motor become energised until the single lock circuit is opened by the gear driven slider. All actuators stop at the single locked position. From this point the external door handles are ‘decoupled’ from the latch mechanism stopping entry from outside of the vehicle.
Assessment Criteria 3.2
Emission control system in vehicles depend on the reduction and discharge of harmful gases from the internal-combustion engine and other components. There are three main sources of gases released from the engine exhaust, the crankcase, and the fuel tank and carburettor. The exhaust pipe sets free burned and unburned hydrocarbons, carbon monoxide, oxides of nitrogen and sulphur, there are traces of various acids, alcohols and phenols. In environmental control system’s the vehicle emissions focusses on types of emissions:
- Hydrocarbons, a class of burned or partially burned fuel, hydrocarbons are a major contributor to smog, causing problems in urban areas.
- Carbon monoxide, is a product of partial combustion, carbon monoxide reduces the blood’s ability to carry oxygen, carbon monoxide poisoning is dangerous and fatal.
- Nitrogen oxide, is produced when nitrogen in the air reacts with oxygen at a high temperature and pressure inside the engine. NOx is a precursor to smog and acid rain. NOx is a mixture of NO, N20, and NO2. NOx production is increased when an engine runs at its most efficient part of the cycle.
- Sulphur oxide, is a term for oxides of sulphur, it is emitted from motor vehicles burning fuel containing sulphur. The reduction of sulphur reduces the level of Sulphur oxide emissions from the tailpipe. Rjdaviesmotor.com (2016)
One environmental control system is the ‘Exhaust Gas Recirculation’ (EGR) exhaust gas recirculation. This is an efficient way to reduce the NOx emissions from the engine. It works by recirculating a quantity of exhaust gas back to the engine cylinders. A valve is used to restrain the flow of gas it may be closed completely if required. The EGR intermixes the recirculated gas with the incoming air reducing the amount of O2 for combustion, lowering the peak temperature of combustion. In other words, the substitution of burnt gas for oxygen rich air reduces the proportion of the cylinder contents available for combustion, causing a lower heat release and peak cylinder temperature reducing the formation of NOx. A presence of an inert gas in the cylinder further limits the peak temperature. The gas is recirculated is usually achieved by piping a route from the exhaust manifold to the intake manifold. The gas recirculated is passed through the EGR cooler reducing the temperature of the gas, reducing the cylinder charge temperature when the EGR is used, the EGR system has two benefits firstly the reduction of charge temperature resulting in lower peak temperature, and secondly the greater density of cooled EGR gas allows for a higher proportion of EGR to be used. On a diesel engine, the recirculated fraction may be as high as 50% under some operating conditions. The control valve within the circuit regulates and times the gas flow.
There are disadvantages and difficulties of an EGR system, especially in diesel engines where the trade-off between NOx and particulates is higher. The EGR reduces the available oxygen in the cylinder, the production of particulates fuel which is only partly combusted is increased when the EGR is applied. The reduction of the oxygen available in the cylinder will reduce the peak power available from the engine. The EGR is usually shut off when full power is required so the EGR approach to controlling NOx fails in this situation. The EGR system cannot respond instantly to changes in demand and the exhaust gas takes time to flow around the EGR circuit. Making the calibration of the EGR behaviour more complex. A faulty EGR system may result in one cylinder receiving too much high particulate emissions while another cylinder receives too little, resulting in high NOx emissions from that cylinders. Cambustion.com (2016)
Diagram3, Cooled Exhaust Gas Recirculation (EGR) System for Tata Hitachi Construction Machinery:
Diagram 4, An EGR Working illustration:
Another environmental control system is a catalytic converter. The catalyst converter changes the harmful pollutants in the exhaust gases into harmless gases. It is located, in the exhaust system and all exhaust gas must move along through it. The catalyst is a material normally platinum palladium in the catalytic converter that causes a chemical change without being a part of the chemical response. The result is the exhaust gas leaving the catalytic converter with less harmful HC, CO, NOx. The catalytic converter converts the pollutants by catalysing a redox reaction (oxidation or reduction). Catalytic converters are used with internal combustion engines fuelled by either petrol or diesel. There are two types of converters:
1. The oxidization catalytic converter – the oxidation catalyst is the second stage of catalyst converter. It reduces the unburned hydrocarbon and carbon monoxide by burning (oxidising) them over a platinum palladium catalyst.
Diagram 5, An illustration showing the oxidization catalytic converter and the various gases emitted from the exhaust:
2. The reduction catalytic converter – The reduction catalyst is the first stage of the catalytic converter, it uses platinum and rhodium to reduce nitrogen oxide emissions.
Diagram 6, The chemical process in the reduction catalytic converter:
Assessment Criteria 3.3
All vehicles are designed to protect the drivers and passengers in a collision, some cars are better at this than others. In a well-designed vehicle, all the different safety systems work together in keeping the driver and passengers safe in many different crash situations. Working together the safety systems make up the occupant protection system. The vehicle must have a strong structure to absorb the crash force while keeping the driver and passenger compartments intact. Passenger safety systems comprise of the following:
- Crumple zones, in the frontal, rear and offset (those occurring at an angle) crashes, modern vehicles protect occupants by absorbing crash energy and reducing the forces in which the driver is exposed. This is because the front and rear sections crumple in a controlled and progressive manner, allowing the driver and passenger compartment to decelerate more slowly. The deceleration signifies less force passing onto the driver and passenger so the injuries are less likely.
- Safety Belts, they are necessary safety fixtures in a vehicle, most modern safety belts have pretensioners. They tighten the safety belt in case of a collision. They have included load limiters which help to control the movements in a collision.
- Airbags, help to stop the driver and passengers from hitting hard parts of the vehicle in moderate to severe crashes. There are many different types of airbags available. Most vehicles manufactured in the last 15 years have driver and passenger frontal airbags. Today’s newer cars have side torso-protecting airbags and side curtain airbags. The side curtain airbags protect a person’s head in a side impact crash.
- Side airbags with head protection, they are a very important safety item which can stop serious injury in a pole-side impact.
- ISOFix child restraint anchorages, there are specified lower anchorage points for the installation of child restraints. These make it easier to install the child restraints correctly.
- Inflatable rear safety belts, the inflatable sections of these safety belts may be shoulder only or lap and shoulder. This system supports the head during a collision, it also provides side impact protection. Inflatable safety belts have tubular inflatable bladders kept within an outer cover. When a collision occurs, the bladder inflates with a gas to increase the area of the restraint which touches the passenger. During a collision at the same time the inflatable rear safety belt shortens in length, tightening the belt around the passenger and improving protection.
- Pre-crash systems, this is a system which discover an immediate collision and automatically puts into action safety devices like safety belt pretensioners.
- Rollover occupant protection systems, detect a rollover situation and deploys occupant protection systems like inflatable curtains. Rollover-enabled air bags are intended to stay inflated after a crash for about five seconds. This give greater protection from the head curtain air bags which deploy in a side-impact collision.
- Active head restraint, a seat is designed to respond to rearward collisions by moving the head restraint forward. It performs other actions to lower the risk of ‘whiplash’ type injuries.
- Head restraint for all seats, they are designed with specific geometry to protect an adult in a road collision from the rear.
- Automatic emergency call (eCall), is a system which alerts the emergency services if a severe collision occurs. Rightcar.govt.nz (2011)
Assessment Criteria 3.4
For instance, the expert checking of the brake and repair procedures and security system for a Porsche Macan model car could detect a defective central locking system which sometimes requires the changing of the small battery inside the key housing by using a small screwdriver. When there is a defective battery the central locking system and car alarm will not work accordingly. There are several steps to take when this happens. Normally, the driver’s door will lock all functioning locking elements of the central locking system, so the emergency locking procedure should be carried out. A qualified Porsche specialist workshop technician should carry out the necessary diagnostics and repair.
To Changing the Driver’s Key (Remote Control Battery) the steps are as follows:
N.B Please observe the regulations for disposing of batteries
If the battery in the remote control becomes too weak, the message ‘Replace Ignition key battery’ will appear on the multi-function display on the instrument panel. The battery should be changed in this case.
To Changing the battery CR 2032, 3 V, you should carry out the following procedures:
- Remove the emergency key.
- Lever off the cover on the back of the key housing using a small screwdriver.
- Change the battery (the polarity should be checked)
- Refit the cover and press together firmly.
- Insert the emergency key.
By using a push and release mechanism the emergency key within the driver’s key is uncovered by using the button to the side. The emergency key can be pulled out and used to unlock the front door of the vehicle. The central locking system controls the doors, tailgate and filter flap. The central locking system is always activated when unlocking and locking the vehicle. On the multi-function display on the instrument panel there are different variants for locking and unlocking the doors and tailgate.
The Alarm System:
The alarm system monitors the following alarm contacts:
- Alarm contacts in doors, tailgate, engine compartments lid and headlights.
- Interior surveillance, movement in the interior when the vehicle is locked, e.g. attempted theft after breaking a window.
- Inclination sensor: Tilting of the vehicle e.g. attempt to tow the vehicle.
- Trailer hitch socket, e.g. unauthorised unhitching of the trailer.
If one of these alarm contacts is interrupted the alarm horn will sound for approximately 30 seconds and the hazard warning lights flash. After a 5 second pause the alarm is triggered again. The cycle is repeated up to ten times. The alarm system is activated when the vehicle is locked, is deactivated when the vehicle is unlocked. When there are faults in the central locking system, the indicator light comes on for 10 seconds, then it flashes at double speed for 20 seconds and then flashes normally.
Although the helpful car alarm is necessary for the security of the car, it can go off unpredictably and even refuse to turn itself off. The safety of the vehicle is very important there are a few methods of troubleshooting the car alarm.
Disabling a Car Alarm:
Disabling the car alarm can be a temporary arranged before getting professional auto assistance. Understanding the basics of an alarm system is very important, there are a few components that an alarm system uses:
- Control unit, this part is often referred to the brain as it functions as the command centre for the system.
- Alarm transmitter, this comes in two forms, key remote or key.
- Sensors, alarms vary and can get complex with very many sensors like pressure, door or window sensors.
- Siren, alarms need some type of warning signal, a few systems have their own siren component while others are wired to the car stereo.
- Wires connect the siren to the control unit, fuses, and the control unit to the sensors.
- Disconnect the battery, to do it open the hood and locate the battery, using a socket wrench unscrew the negative terminal (-) of the battery and pull it off. This is a safety measure to prevent accidents because working with the vehicles electronics can be dangerous.
- Find the alarm system, it can usually be found under the hood near the steering wheel.
- Disconnect the wire’s, some alarm control units have labels for each wire’s, by taking off the wires attached to the control unit and removing the wires attached to the siren, are two ways to disable and silence the alarm.
- Pull the wire of the siren, this will silence the alarm.
- Reconnect the battery and test the car, put the plug of the battery back in, to make sure the alarm is not going off again. Turn on the car and give the engine an increase of speed. This will make sure that the car can still function. M.wikihow.com (2016)
Assessment Criteria 3.5
The reduction of oxides of nitrogen (NOx) engines have been equipped with exhaust gas recirculation (EGR) valves. The EGR valves opens at speeds above idle on a warm engine. When the valve is open, it allows a small portion of the exhaust gas to enter the intake manifold. The exhaust gas is recirculated and takes the place of some the intake mixture. The recirculated exhaust gas is without power and does not enter the combustion process. Diagnosing a defective EGR valve is very straight forward. If the EGR valve is not working or the flow of the exhaust gas is within limits, then the following symptoms will happen:
- A spark-knock is created when there is an increase of speed during normal driving
- Excessive oxides of nitrogen (NOx), exhaust emissions.
If the EGR valve is stuck open, then these symptoms will show:
- Rough idle or loss of speed
- Poor performance/low power
The first step in diagnosing the fault is to perform a thorough visual inspection. Checking the proper operation of a vacuum operated EGR valve.
To check the operation of the Vacuum-Operated EGR valve, we have to:
- Check the vacuum diaphragm to see if it can hold the vacuum. N.B. Because some EGR valves require exhaust back pressure to work correctly, the engine should be running at the correct RPM.
- Apply vacuum from a hand operated vacuum pump and check for right operation. The valve should move when the vacuum is applied and the engine operation should be moving. The EGR valve must be able to hold the vacuum that was applied. If the vacuum drops off, then the valve is likely to be defective. Pearsoned.ca (2016)
It is useful to know that the central locking system unlocks all doors of a car and it is controlled by a key with a unique code which synchronizes with the car’s alarm system. Once the key is used for locking the car the engine immobilizer will go off. Then the vehicle’s computer system will work with the same code from the car key, therefore opening the engine immobilizer. Consequently, when the engine immobilizer is on, the car will not start. With the evolution of time the central locking system has advanced in their working and is now operated remotely from a distance.
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In question 3.2 I have understood that emissions of many air pollutants have shown a variety of negative effects on public health and the environment. Emissions such as hydrocarbons a class of burned or partially burned fuel are very toxic. Smog is a major contributor to pollution, and prolonged exposure to hydrocarbons contribute to asthma, liver disease, lung disease and cancer. Carbon monoxide is a product of incomplete combustion which reduces the bloods ability to carry oxygen. Carbon monoxide poisoning is a killer in high concentrations.
However, the Exhaust gas recirculation system (EGR) was firstly used in the USA and Canada in the 1970’s and later developed by major car manufacturers to lower the harmful gases released into the atmosphere. Dr Donald H. Stedman of the University of Denver invented technology using infra-red to detect the exhaust gases used in urban areas. It is a way of testing the various gases released into the environment. Finally, I can say that with the advancement of time technology has improved the design and security of the car to ensure the safety of the vehicle.
- Cambustion.com (2016) Exhaust Gas Recirculation (EGR) and NOx Measurement, NOx Emissions [online] Available at: http://www.cambustion.com/products/egr [Accessed: 28th March 2017]
- My-cardictionary.com (2016), Central Locking System [online] Available at: http://www.my-cardictionary.com/accessories/central-locking-system.html [Accessed: 28th March 2017]
- Pearsoned.ca (2016) Emission Control Devices Operation, Diagnosis, and Service [online] Available at: http://www.pearsoned.ca/highered/divisions/virtual_tours/halderman/data/Halderman_AutoTec_ch30pdf [Accessed: 28th March 2017]
- Quickhonda.net (2016) Exhaust Flow in an Automobile [online] Available at: http://www.quickhonda.net/exhaust.htm [Accessed: 28th March 2017]
- Rightcar.govt.nz (2011) Protection Systems During A Crash [online] Available at: http:///rightcar.govt.nz/protection-during-a-crash.html [Accessed: 28th March 2017]
- Rjdaviesmotor.com (2016), R.J. Davies Motor Repairs, [online] Available at: http://rjdaviesmotor.com/services/emission-problems/ [Accessed: 28th March 2017]
- Sine.ni.com (2016) Using Compact RIO and Lab VIEW to Reduce NOx Emissions from Ship Engines [online] Available at: http://sine.ni.com/cs/app/doc/p/id/cs-12978/lang/en/pdf/yes/pdf [Accessed: 28th March 2017]
- Unofficialbmw.com (2016), Central Locking, Purpose of the System [online] Available at: http://www.unofficialbmw.com/images/lock.pdf [Accessed: 28th March 2017]
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