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by PAUL BASTOCK
Until about twenty years ago, the aver age car contained only one capacitor, fitted across the contact breaker points to reduce arcing. Today, the figure has grown to around 100 capacitors per vehicle, due mainly to the meteoric growth in the number and complexity of in-car entertainment systems. At present, about 30% of new cars are equipped with some form of audio equipment, predicted to rise to approximately 70 per cent by the start of the next decade. There is every reason to sup pose that the number of capacitors in these units will increase as more and more features are incorporated. Already, push button radio tuning is accomplished by electronics rather than a mechanically-variable inductive tuner.
But this market is a rather static one; in-car entertainment is the biggest user of capacitors at the moment, but this isn't where expansion will take place. Driver surveys commissioned by the car industry have revealed, not surprisingly, that the average car owner regards electronics as something of a gimmick. This hasn't been helped by the introduction of voice synthesizers and difficult-to-read liquid crystal displays on some up-market cars. Electronics is chiefly of interest to the driver if it brings improved performance, better fuel economy or increased reliability; it interests the manufacturer if it achieves these goals profitably. However, the appeal of gadgets to the potential car buyer must not be forgot ten. In the US, strict emission control requirements have provided an impetus to the development of engine management systems which until recently has been lacking in Europe. [See Microprocessor-controlled engine management. by Pat Jordan. EWIV September 1987.]
One of the first areas to move away from mechanical and electromechanical operation into electronics was electronic ignition. This apparently simple function gave manufacturers and designers their first taste of the problems involved in installing electronic units in the electrically noisy, hot and vibratory environment of a typical engine compartment. Capacitor discharge units dominated this application at first, but failures due to the extreme stresses imposed on the output capacitor, both in terms of voltage and current handling, gave electronic ignition an undeserved reputation for unreliability. Now, most such units use inductive energy storage, coupled with a Hall-effect magnetic field sensor to give feedback control for spark optimization.
Fuel-injected cars also require electronic control systems, ranging from simple pro gram controlled open-loop networks to more complicated feedback systems. Some manufacturers have used electronic fuel management successfully on cars using carburetors.
Currently, some 60% of new cars have some form of electronic engine management. Indications are that by 1992, all vehicles sold in the EEC will have some form of electronic engine management, particularly as EEC pollution regulations favor electronic control rather than catalytic systems.
Some analysts include automatic trans mission systems under the heading of engine management. The traditional automatic gearbox uses a complex series of pressure-sensitive valves to determine when to change gear, but there is a new breed of transmission units which employ power FETs under the control of a microprocessor for improved reliability. The next decade should see about 40% of cars with this variety of automatic transmission.
Safety and security. The principal use for electronics in safety is in the control unit for anti-lock braking (ABS), which many car makers are offering as an, albeit rather expensive, option. This is another field in which electromechanical systems are being supplanted by electronic control. It is feasible to implement a self-adjusting servo actuated suspension system; indeed this is already being done, but the extremely high cost of the sensors will limit this aid to road-holding to very expensive vehicles, unless there is a major technology break through in the near future.
More likely to expand is the area of electronic security. Indeed, electronic lock encoding and security marking of stereo equipment is present-day rather than future technology, even for medium-priced cars.
Comfort and convenience. Electronic 'C & C' systems are almost unknown, but prestige cars are beginning to use various means of electronic driver environment control. Some particular models feature a microprocessor unit which governs the operation of the air-conditioning, a task formerly entrusted to relays and bimetallic sensors. The driver's seat position and shape can also be controlled by an electronic system via electric or hydraulic actuators.
Inevitably, this category of equipment will remain a fitment for only the most expensive vehicles. The best predictions currently available indicate that around 25% of new cars will have some electronic comfort control by 1990.
Dashboard instrumentation. Despite a number of widely-differing high-tech dash board layouts seen on cars in the last couple of years, driver reaction has not on the whole has been favorable, so the market has yet to find a direction when it comes to digital or liquid crystal information displays. Possibly a quarter of all cars will have an electronic dashboard within the next few years, but this is a very debatable figure.
THE MARKET FOR CAPACITORS
Assuming that all the trends mentioned are accurate, the average car in 1990 should have some 500 capacitors fitted by the factory. With an estimate of 10 million new cars on the roads in Europe by then, this makes for a very large volume of capacitor production to very exacting quality standards. None of the above arguments takes into account the growing use of plastics for body panels, which will inevitably degrade the screening between different electronic units within the car, so these figures might even represent an underestimate, assuming that decoupling remains cheaper than using screened cable. A modem car uses up to 5km of wiring, so screening is certainly an expensive option.
Problems for component suppliers. Few applications require such a large volume of production as does the automotive industry.
A typical production line will consume many thousands of electronic units per week, even in medium-volume manufacture; mass-market cars are made at even higher rates. It is this sheer volume which has tended to exclude the small component manufacturer for very high reliability, one-per-car units like ABS control boxes. There is room for the small supplier, but generally they must be capable of producing components in huge numbers. For a car manufacturer, price is all-important, with assured quality a very close second. Most car producers will expect a product specifically tailored to his own need, with SPC (Statisitical Process Control) figures supplied well in advance of a firm order. It can easily take two years to develop a component exactly to the buyer's requirements, and there is no guarantee that any other manufacturer will be interested in the same component as his rival. But having designed the component and assuming that failure levels of a few parts per million can be achieved, the component supplier is usually rewarded with a four-year contract with production quantities scarcely dreamed of in other fields.
Space for electronics. Although the number of electronic functions is increasing, the size of the car into which units must be fitted isn't changing appreciably. Already there is strong competition for the prime spots, such as under the dashboard where temperature ranges are restricted, so units are being sited under wings, in the boot, anywhere in fact but in the electrically noisy and hot area under the bonnet. The tendency to overheat is exacerbated by present-day drag reduction programs, which reduce the volume of air flowing into the engine compartment.
This places a premium on small size, so surface mounting of devices has caught on in the automotive sector much faster than in some other industries. This is good news for multilayer ceramic capacitor makers, since today's plastics-film capacitors are difficult to surface-mount without the risk of thermal damage to the dielectric. Surface mounting brings other advantages, of course, chiefly that of reduced r.f. pickup brought about by minimal lead length and therefore minimal inductance.
The automotive market represents one of the few areas in which really high-volume electronics production is likely to continue to expand. The workhorse at the moment is the eight-bit microprocessor, though the newer microcontrollers with their on-chip ram and multiple i/o ports are ideal for this type of process control and are rapidly gaining ground. Sixteen-bit processors will probably not be used in the near future as eight-bit accuracy is sufficient for all present needs in a car.
Mechanical and electromechanical units will continue to be replaced by electronics, with closed-loop control and its attendant advantages in the majority of applications.
This will mean an enormous market for low-cost, reliable sensors of every type, provided that they can be made cheaper than and at least as reliable as their electromechanical counterparts. All kinds of passive components, with particular emphasis on capacitors and resistor arrays in surface mount able form, will be needed in vast quantities.
Almost every control box will have at least one power mosfet to do the mundane but necessary job of switching the solenoid valves and electrical actuators. Companies prepared to invest the large sums needed to make components in millions at high re liability will benefit immensely from this expanding industry.
Paul Bastock works at the newly acquired AVX plant in Paignton, Devon.
(adapted from: Wireless World , Oct. 1987)