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The role of sensors and sensing technologies for the next generation vehicle systems are discussed. The control systems for engines and power-train are expected to realize high efficiency with low pollution and comfort drivability. Vehicular safety and chassis control systems are expected to avoid many kinds of traffic accidents caused by the human errors of drivers. Vehicular information systems will help the drivers to get the information to manage their vehicles economically and efficiency. In every system mentioned above, sensors and sensing technologies are playing an increasingly important role. This paper introduces and discusses essential technologies for sensors and sensing which can be expected to bring the solutions to the future automotive systems.

This report describes the development of an air fuel ratio sensor with a linear voltage output, and its signal processing module that is able to calibrate the sensor output function on the measuring point of the 20.9% oxygen concentration in atmospheric air and the zero diffusion current at stoichiometry as the reference. This sensing system is effective when applied to air fuel ratio PID feed back engine control and it is able to realize the reduction of initial variability of sensors, interchangeability of sensors, and long term output change of the sensor.

To detect an air-fuel ratio in wide range is very important to control the automotive engines with low fuel consumption and low exhaust emissions. Although the application of zirconia electrolyte for this purpose has been proposed by the authors several years ago, there remained several problems due to the contamination of gas diffusion apertures which are exposed to the exhaust gas environment. Here the behavior of ions transported in zirconia electrolyte have been analyzed to optimize the structure and characteristics, and to guarantee the long life operation of sensor. Gas contents and their reactions in combustion process under the wide range air-fuel ratio have been analyzed, and these results were reflected to the analysis of ion transportation in zirconia electrolyte. Experimental results supported the analytical results, and they showed the possibilities of long life operation of zirconia air-fuel ratio sensor utilizing ion transportation phenomena.

Plastic optical fiber has been widely used in the field of short distance optical transmission. However heat resistance of commercial plastic fiber is so low that its applications are limited. Then, a plastic fiber of thermosetting acrylate resin core has been developed. This fiber shows 80%/m retention of light transmittance at 1m after 1,000 hours at 150°C. It resists heat deformation and withstands up to 200 °C for a short time period. Tests show this fiber has desirable mechanical characteristics, along with good environmental resistance. In addition, a fiber which has a silicon resin as a core material was developed which has even better heat resistance.

Engine performance has been investigated of currently gasoline powered passenger car engines converted to methanol and gasoline mixtures. A 4 cycle, 4 cylinder, 1.6 liter displacement engine for a conventional passenger car was tested varying the fueling condition. The mixing ratio of methanol to gasoline was changed from zero percent to one hundred percent, discreetly. Evaluation of engine performance was made to find the optimum air-fuel ratio and spark timing in each mixed fuel condition. It has been clarified that the stoichiometric air-fuel ratio in the mixed fuel can be determined by the mixing ratio P, as an expression of The MBT(minimum spark advance for the best torque) characteristics for each mixed fuel codition show that the large retardation of spark timing will be required for the higher mixture ratio fuels. Changes in characteristics of fuel supply and air-fuel ratio sensing devices were investigated experimentally.

A multiplexed transmission system utilizing newly developed optical polymer has been proposed. The system is composed of a star-shaped optical network, in which optical signals can be transmitted bi-directionally through a fiber and optical branches between the central and local controllers. The new polymer optical fiber has been developed and adopted for this system, and it was designed to be durable to the high temperature in automotive engine rooms. The high temperature resistibility of the fiber has been achieved with utilization of a thermo-setting resin for the core materials. The optical loss characteristics of the fiber is as low as 0.50 dB/m at 660 nm wavelength.

This paper describes the sensing principle of a new air-fuel ratio sensor, which has the ability to detect air-fuel ratios in rich, stoichiometric and lean ranges. The sensing part is composed of a gas diffusion layer and a zirconia solid electrolyte with a pair of electrodes which function as an anode and a cathode. The anode and the cathode electrodes are exposed to the atmosphere and the exhaust gas, respectively. To obtain the bidirectional pumping current between the two electrodes, the potential of the cathode is held to a constant value higher than the electronic circuit ground. The electromotive force induced between the two electrodes is forcibly controlled to a constant value by the electronic circuit. In this composition, three ranges of air-fuel ratio can be detected by the amount of pumping current.

This paper describes the design and operation of a thick-film zirconia air-fuel ratio sensor with a heater. This sensor is composed of two zirconia plate cells, a stoichiometric cell and a lean cell, laminated on the platinum heater. It is fabricated as one body using a thick-film process. The pair of cells has a gas diffusion chamber and a slit type gas diffusion aperture. The sensing principle is based on the rate-determining diffusion of oxygen molecules at the gas diffusion aperture. By using an oxygen pumping phenomenon, air-fuel ratios of the stoichiometric and lean regions can be detected. As this sensor is heated to a high constant temperature, it has sufficient accuracy without any additional temperature compensation. Its starting time is short and response time is very quick.

A new robust hot wire air flow meter with wire winding probe, to be located in the bypass air passage of the intake air passage, was developed for an electronic engine control system. This bypass type hot wire air flow meter can measure mean air velocity precisely in pulsating flow when the length of the bypass passage and the pressure loss in the bypass are selected appropriately.

A hot-wire air flow sensor which can directly measure the intake air mass flow has been developed, and a microprocessor based engine control system using the sensor has been designed. The sensing probe of the sensor is formed from a small wire-wound resistor, and installed in the bypass of the intake passage. The sensor requires a good signal processing method under pulsating flow conditions because of its quick response. New control technologies were examined for the prototype engine control system, using the sensor, as applied to a 4 cycle, 4 cylinder engine. The air-to-fuel ratio, ignition timing, and EGR rate are controlled to their optimum values by a microprocessor which processes signals of this sensor and of other sensors indicating the engine operating conditions. The results of engine performance tests show that the output power, fuel economy and exhaust emissions are improved significantly in comparison with other fuel management systems.

The current status of automotive electronics in Japan and the prospects for the ’80s are described in this paper. Semiconductor technologies are focused on first. Such technologies have been the greatest driving force for progress in automotive electronics, and will undoubtedly continue to be so in the future. The cost-performance ratio of semiconductor systems will increase several tenfold this decade. Highly integrated CMOS LSIs will replace other LSIs in automobiles, because they are better suited to the severe conditions found in automotive systems. New solid-state sensors and actuators using new materials and technologies will be developed in this decade. Microprocessor control systems will spread to most makes and models of cars in this decade. Control technology will become more sophisticated. Some on-vehicle systems will be linked to each other and on- and off-vehicle networks will be developed.

Dynamic characteristics of fuel supply system for multi-cylinder gasoline engine was studied analytically and experimentally. We investigaged. (1) The relation between the air flow rate upstream the throttle valve and the air flow rate into the cylinder, when the throttle valve is opened or closed rapidly. (2) The air fuel ratio in the cylinder affected by the above relation. (3) Pmax response affected by the residual fuel in the intake manifold.

A new input and output (I/O) signal processing concept for microprocessor engine control systems is presented. An analysis of the relations between data resolution and control accuracy show that they are effected by sensor signal forms. The concept of a microprocessor engine control system with a specially designed I/O interface LSI is proposed. An output circuit with a structure that allows fast data processing and minimizes LSI chip size are also presented.