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About this book

This is a complete reference guide to automotive electrics and electronics. This new edition of the definitive reference for automotive engineers, compiled by one of the world's largest automotive equipment suppliers, includes new and updated material. As in previous editions different topics are covered in a concise but descriptive way backed up by diagrams, graphs, photographs and tables enabling the reader to better comprehend the subject. This fifth edition revises the classical topics of the vehicle electrical systems such as system architecture, control, components and sensors. There is now greater detail on electronics and their application in the motor vehicle, including electrical energy management (EEM) and discusses the topic of inter system networking within the vehicle. It also includes a description of the concept of hybrid drive a topic that is particularly current due to its ability to reduce fuel consumption and therefore CO2 emissions.This book will benefit automotive engineers and design engineers, automotive technicians in training and mechanics and technicians in garages. It may also be of interest to teachers/ lecturers and students at vocational colleges, and enthusiasts.​

Table of Contents

Frontmatter

Electrical and electronic systems in the vehicle

The amount of electronics in the vehicle has risen dramatically in recent years and is set to increase yet further in the future. Technical developments in semiconductor technology support ever more complex functions with the increasing integration density. The functionality of electronic systems in motor vehicles has now surpassed even the capabilities of the Apollo 11 space module that orbited the Moon in 1969.

Basic principles of networking

With the tremendous speed at which computer technology is advancing, the number of electronic systems in use is increasing more and more. This growth is also continuing in automotive engineering. However, this also means that the complexity of an overall system (the vehicle in this case) is on the increase. Individual systems such as engine management have been improved over the last few years. However, innovations are mainly achieved by means of interaction between several individual systems. The individual components need to be networked so that the multitude of information that is managed by the individual systems can also be used elsewhere throughout the system. Different communication systems are used depending on requirements (e.g. transmission reliability, fault tolerances, costs).

Automotive networking

Electrical and electronic systems in motor vehicles are often not independent of each other but influence and complement each other. For this reason, signal lines were used in previous injection and ignition systems in order to simplify communication between these two systems. However, the increasing number of electronic systems rapidly increased the demand for and the scope of the information that was being exchanged. The number of signal lines and plug connections that is required increased accordingly, meaning that the technology that has so far been used was approaching the limit of its capability.

Bus systems

In 1991 the CAN bus (Controller Area Network) was the first bus system to be introduced to a motor vehicle in mass production. It has since established itself as the standard system in the automotive sector, but the CAN bus is also commonly used as a field bus in automation engineering in general. In imitation of other network types, such as the local area network (LAN), wide area network (WAN) or personal area network (PAN), this bus system was given the name, CAN.

Architecture of electronic systems

Over the last three decades, tremendous progress has been made in automotive engineering. Modern injection and exhaust-gas treatment systems drastically reduced pollutants in the exhaust gas, while occupant-protection and vehicle stabilization systems improved safety on the road. Much of this success is due to the introduction of electronically-controlled systems. The proportion of these systems used in cars increased continuously. The requirements of safety and environmental compatibility, but also the demand for comfort and convenience functions, will increase yet further and this will in no small part be achieved through the use of electronics. Up to around 90 % of innovations in the motor vehicle will be realized by electronics and microprocessor-controlled systems. The networking of these electronics creates the prerequisite for having this wide variety of electronic systems integrated within the complete vehicle system to form a whole. However, this results in a complexity that can only be overcome at considerable expense.

Mechatronics

The term “mechatronics” came about as a made-up word from mechanics and electronics, where electronics means “hardware” and “software”, and mechanics is the generic term for the disciplines of “mechanical engineering” and “hydraulics”. It is not a question of replacing mechanical engineering by “electronification”, but of a synergistic approach and design methodology. The aim is to achieve a synergistic optimization of mechanical engineering, electronic hardware and software in order to project more functions at lower cost, less weight and installation space, and better quality. The successful use of mechatronics in a problem solution is dependent upon an overall examination of disciplines that were previously kept separate.

Electronic components in the vehicle

Since the first electronic systems were introduced in the passenger car sector in the 1960s, the proportion of electronics in the motor vehicle has steadily risen. The first components to be used were predominantly discrete components. However, manufacturing costs and high requirements for system reliability soon inhibited their further development. Technological advances in microelectronics promoted the increasingly dense integration of components. This gave rise to compact, dependable electronic systems for automotive applications.

Control units

Digital technology furnishes an extensive array of options for open and closed-loop control of automotive electronic systems. A large number of parameters can be included in the process to support optimal operation of various systems. The control unit receives the electrical signals from the sensors, evaluates them, and then calculates the triggering signals for the actuators. The control program, the “software”, is stored in a special memory and implemented by a microcontroller. The control unit and its components are referred to as hardware. The Motronic control unit contains all of the algorithms for open and closed-loop control needed to govern the engine-management processes (ignition, induction and mixture formation, etc.).

Automotive sensors

The term sensor has become common, as in the past 20 to 40 years measuring gages have also come into use in consumer applications (e.g. motor vehicle and domestic appliance technology). Sensors – another term for measuring detectors or measuring sensors – convert a physical or chemical (generally non-electrical) variable Φ into an electrical variable E; this process often also takes place over further, non-electrical intermediate stages.

Sensor measuring principles

There is a great number of sensors at work in motor vehicles. They act as the sensory organs of the vehicle and convert input variables into electrical signals. These signals are used in control and regulation functions by the control units in the engine-management, safety and comfort and convenience systems. Various measuring concepts are applied, depending on the task.

Sensor types

Engine-speed sensors are used in engine-management systems for
  • ► Measuring the engine speed and
  • ► Determining the crankshaft position (position of the pistons)
The engine speed is calculated from the interval between the speed sensor’s signals.

Actuators

Actuators (final-control elements) form the interface between the electronic signal processor (data processing) and the actual process (mechanical motion). They convert the low-power signals conveying the positioning information into operating signals of an energy level adequate for process control. Signal transducers are combined with amplifier elements to exploit the physical transformation principles governing the interrelationships between various forms of energy (electrical – mechanical – fluid – thermal).

Hybrid drives

As well as optimizing conventional drive concepts, motor vehicle manufacturers also rely on alternative concepts in order to ensure that existing and future noise and emission restrictions are complied with and reduce fuel consumption. The use of hybrid cars as a means of reducing environmental pollution and increasing driving pleasure and comfort is becoming increasingly popular.

Vehicle electrical systems

The vehicle electrical system of a motor vehicle comprises the alternator as the energy converter, one or more batteries as the energy accumulators and the electrical equipment as consumers. The energy from the battery is supplied to the starter (consumer), which then starts the vehicle engine. During vehicle operation, the ignition and fuel-injection system, the control units, the safety and comfort and convenience electronics, the lighting, and other equipment have to be supplied with power.

Starter batteries

The starter battery is an electrochemical storage facility for the excess electrical energy that is generated by the alternator while the engine is running. This stored energy is needed during vehicle operation in the phases when the energy required by the active consumers is greater than the energy that is generated by the alternator (e.g. at idle speed). The battery also provides the energy that is required by the electrical consumers when the engine is stopped and for starting the engine. The battery can be recharged again when it has discharged. It is therefore a storage battery accumulator, in this case a lead storage battery.

Alternators

Motor vehicles have an alternator to generate electrical energy for supplying power to electrical consumers such as the starter, ignition and fuel-injection system and electronic control units, etc. The alternator also charges the battery if it generates more current than the consumers need. Alternator output power, battery capacity and the power requirement of the electrical consumers must be matched to each other to ensure that sufficient current is supplied to the vehicle electrical system in all operating conditions and that the battery is always adequately charged.

Starting systems

Internal-combustion engines must be cranked by a starter at a minimum speed before they can supply sufficient energy in sustained operation from the combustion cycles to cover the momentary requirements for the compression and gas exchange cycles. When an engine is first started, the bearing surfaces are not adequately lubricated so that high levels of friction have to be overcome when cranking the engine.

Electromagnetic compatibility (EMC) and interference suppression

Electromagnetic compatibility (EMC) consists of two elements. One is understood as the ability of a device to continue providing reliable service when exposed to electromagnetism from external sources. The second aspect focuses on electromagnetic fields generated by the same device; these should remain minimal in order to avoid creating interference that would impinge upon the quality of radio reception, etc. in the vicinity.

Backmatter

Additional information

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