Automotive Electronics: A concept review

AUTOMOTIVE ELECTRONICS

Sathish Kumar scholar of BE-Mechatronics Engineering, K.S.Rangasamy College of Technology

Sathish Kumar scholar of BE-Mechatronics Engineering, K.S.Rangasamy College of TechnologyPrefinalyear

Email id:sathishdotgs@gmil.com

Veeranam.sathish@gmoil.comPhone no: 95786300441. Abstract

The car as a self-contained microcosm is undergoing radical changes due to the advances of electronic technology. We need to rethink what a car really is and the role of electronics in it. Electronics is now essential to control the movements of a car, of the chemical and electrical processes taking place in it, to entertain the passengers, to establish connectivity with the rest of the world, to ensure safety. Although electronics is now used extensively on mid-range and smaller cars, the adoption of many electronic systems will remain in the luxury/executive car sectors.

This paper aims to review all the concepts of automotive electronics. The areas of automotive system analyzed for the paper have been split into five main areas: Power train, Chassis and body, Display and instrumentation, Safety and convenience and System level.

The concepts discussed in power train area are Electronic ignition, Electronic alternators/rectifiers, Electronic voltage regulators, Fuel injection petrol, Engine management systems, Diesel engine management systems, Electronic throttle (drive-by-wire), Cruise control Electronically-controlled transmission and Electronically-controlled all-wheel-drive. The concepts discussed in chassis and bodies are Anti-lock braking, Traction control, Stability management, electrically controlled steering, and Suspension (ride control, semi-active, and active). The concepts discussed in Instrumentation and Display are primary electronic displays (vacuum fluorescent, LCD) and Electronic drivers for analogue instrumentation. The concepts discussed in safety/convenience are Passive restraint airbags, motorized seatbelts, Driver Assistance, Automatic air conditioning, Trip computer/driver information centers, Navigation, Anti-theft devices (factory installed), Keyless entry, Central door locking, Power windows, Wiper modules, Power seat, Power mirror, Power sunroof, Lighting, and Body Controllers. The concepts discussed in system level are Multiplexing/Networking, Electrical Distribution and Diagnostics.

In each area the application of electronics have been discussed in detail with suitable diagram, circuits and discussions. Suitable examples are also given from Indian automotive industry.

2. IntroductionSome of the present and potential applications for electronics are Electronic engine control for minimizing exhaust emissions and maximizing fuel economy, Instrumentation for measuring vehicle performance parameters and for diagnosis of on-board system malfunctions, Driveline control, Vehicle motion control, Safety and convenience and Entertainment/communication/navigation.

The areas of automotive system analyzed for the paper have been split into five main areas: Power train, Chassis and body, Display and instrumentation, Safety and convenience and System level.3. Power TrainThe following applications are discussed in power train.

3.1 Electronic ignition The spark advance (relative to TDC) is determined in the electronic engine control based on a number of measurements made by sensors.

3.2 Electronic alternators/rectifiers and Electronic voltage regulators

A voltage regulator controls alternator output by changing the amount of current flow through the rotor windings. 3.3 Fuel injection petrol

The major advantage of any type of fuel injection system is accurate control of the fuel quantity injected into the engine. The basic principle of fuel injection is that if petrol is supplied to an injector (electrically controlled valve), at a constant differential pressure, then the amount of fuel injected will be directly proportional to the injector open time.3.4 Engine Management System

An engine management system integrates numerous elements, including; An engine control module (ECM), Control and diagnostics software, An air induction and control subsystem, A fuel handling module, A fuel injection module, An ignition subsystem, A catalytic converter, A subsystem to handle evaporative emissions and A variety of sensors and solenoids.3.5 Diesel Engine Management System

Ideal values for fuel quantity and timing are stored in memory maps in the electronic control unit. The injected fuel quantity is calculated from the accelerator position and the engine speed. The start of injection is determined from Fuel quantity, Engine speed, Engine temperature and Air pressure. The ECU is able to compare start of injection with actual delivery from a signal produced by the needle motion sensor in the injector.

3.6 Electronic throttle (drive-by-wire) and Cruise control

The throttle potentiometer is fixed on the throttle butterfly spindle and informs the ECU of the throttle position and rate of change of throttle position. Cruise control (sometimes known as speed control or autocruise) is a system that automatically controls the speed of a motor vehicle. The system takes over the throttle of the car to maintain a steady speed as set by the driver.3.7 Electronically-controlled transmission and all wheel drive

The proper gear ratio is actually computed in the electronic transmission control system. Modern Four-Wheel Drive (4WD) systems have become very sophisticated and infused with electronic control technology.4. Chassis and Body

The following applications are discussed in Chassis and body.

4.1 Anti-lock braking and Traction control

In ABS-equipped cars, the wheel is prevented from locking by a mechanism that automatically regulates braking force to an optimum for any given low-friction condition.

The traction control or Vehicle Stability Assist (VSA) system attempts to stabilize the vehicle in the event of a loss of traction or wheel slippage. The slippage may be caused by spinning the wheels in the snow, but the system is designed to stop a spinout on a slippery curve taken at an excessive speed. The VSA applies the brakes on the wheel that is spinning and reduces power output to the other wheels.

4.2 Stability management and electronically controlled steeringElectronic stability control (ESC) is a computerized technology that improves the safety of a vehicle's stability by detecting and minimizing skids. When ESC detects loss of steering control, ESC automatically applies the brakes to help "steer" the vehicle where the driver intends to go. Braking is automatically applied to individual wheels, such as the outer front wheel to counter oversteer, or the inner rear wheel to counter under steer. Some ESC systems also reduce engine power until control is regained.[1] Electronic stability control does not improve a vehicle's cornering performance; rather it helps to minimize a loss of control.

Electrically powered steering uses an electric motor to drive either the power steering hydraulic pump

or the steering linkage directly.

4.3 Suspension

The main purpose of the ECS is to adapt the suspension of the car into the driving conditions taking account the speed, surface of the road, cornering, stopping requirements and acceleration. The aim is to increase safety and driving comfort..

5. Display and instrumentationThe following applications are discussed in display and instrumentation.5.1 Primary electronic displays and Electronic drivers The main instruments are the speedometer, the oil pressure gauge, the thermometers indicating the temperature of the engine cooling fluid, the inner and outer temperatures, the battery voltmeter, the ammeter, the fuel gauge indicating the amount of petrol in the tank, etc. 6. Safety and convenienceThe following applications are discussed in safety and convenience.

6.1 Passive restraint airbags and Seat belts retractor

The sensors represent the brain and nerves of the system, which detect and decide whether and when to initiate the inflator. The inflator either generates or releases gas to deploy the bag. The bag is fully inflated before the occupant makes contact with the bag without inflicting unnecessary forces on the occupant. Retractor is a device, which manages the tension on the seatbelts and operates the seat belt according to signal received from the ECU. Virtually all retractors have two sensors that work independently on the locking mechanism. The vehicle sensor detects sudden retardation of the vehicle, while the webbing sensor detects violent pullouts of webbing from the retractor.

6.2 Automatic air conditioning Full Automatic Temperature Control (FATC) features completely automatic control of discharge air temperature. FATC also controls the circulation and humidity of the air inside the vehicle. With FATC, the driver selects the temperature and the FATC functions to maintain that temperature, regardless of outside temperature changes.

6.3 Trip computer/driver information centers and Navigation

The most common suite of driver assistance technologies available today includes adaptive cruise control (ACC), lane change assistance, and parking assistance systems. The display portion of a research system is typically a CRT. As the car approaches its destination, the map detail should increase until the driver can locate his or her position within accuracy of about half a block.

6.4 Anti-theft devices and Keyless entry The device, called iCATs (intelligent Computerized Anti-Theft system) works on the principle of multiplexed communication. 6.5 Power windows, Power Seat, Power mirror, and power sunroof A control device for power operated systems of automobiles where the electric motor is controlled by a switch which is operated by the control lever of the system mechanism whenever the closed position is reached. The control lever includes a cam arm portion guided by a cam groove which operates the switch.6.6 Wiper modules, Lighting and Body controller

A rain sensor unit controls the speed of wipers based on the amount of rain. An electronic control unit analyzes the input signal of the input unit. An output unit controls the output integrated circuits, and adjusts and controls the driving of the wiper motor.

Intelligent lighting systems can be designed with the aid of advent electronic technology.

The BCM supports many body electrical features such as Interior Lighting, Exterior Lighting, Intermittent Wipers, Remote Radio, Accessory Delay, and Heated Seats.

7. System level

The following applications are discussed in power train.7.1 Multiplexing/Networking and Electrical DistributionInstead of a mechanical switch, the actual switching is done by means of a solid-state electronic switching device called a multiplexer (MUX) that selects one of several inputs for each output. Multiplexing can be done either with analog or digital signals.

7.2 Diagnostics

Each microprocessor-based electronic subsystem has the capability of performing some limited self-diagnosis. 8. Conclusion

Whether or not any of the concepts discussed here ever reaches a production phase will depend largely on its technical feasibility and marketability. Some will simply be too costly to have sufficient customer appeal and will be abandoned by the major automobile manufacturers. 9. References

1. Understanding Automotive Electronics, William B. Ribbens, ButterworthHeinemann, 1998

2. Automotive Electrical and Electronic Systems, Tom Denton, Elsevier 2000

3. Automotive Computer Controlled Systems, Allan Bonnick, Butterworth Heinemann, 2001

4. www.autoshop11.com5. www.wikipedia.org