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As new smart systems for passenger cars are assisting me driver to handle manoeuvres in critical and normal situations, brake systems are required to fulfill the compatibility and interface demands. These advanced brake systems will be operated in a remote mode during normal braking and for autonomous brake interventions. BOSCH is developping a brake-by-wire system on a hydraulic basis, called ‘Electrohydraulic Brake EHB’. Brake pressure buildup is supplied by a high pressure accumulator. Generation of the high pressure is done by an electric motor driven pump, similar to current ABS-systems. Pressure at the wheel brakes is individually controlled by closed-loop pressure control, consisting out of inlet, and outlet valves, pressure sensor and corresponding algorithm. It is specified, that this control must be completely noiseless, proportional, fast, and highly accurate. To raise the acceptance of such a system, it will be introduced with a conventional hydraulic backup.

Because of the unique control characteristics of electrohydraulic proportional valves-smooth acceleration and deceleration, and the ability to inch or feather the work platform into position-several methods have been devised to use electrohydraulic valves to control electrically insulated aerial lifts. Since all components bridging the insulated portions of the boom structure must have an insulating value equivalent to the boom itself, it is not permissible to run electrical control cables from the work platform down the insulated boom to the control valves mounted on the chassis below. Systems using radio signals and light signals (via fiber optic bundles) are being developed to control the more complex, multifunctional aerial lift boom structures.

Hydrostatic Transmissions have gained widespread acceptance on mobile equipment over the last decade. They offer an efficient means to transmit energy at high power levels, while maintaining smooth proportional control. In the last few years, electrohydraulic devices have become available for stroking pump and motor swashplates with small electrical signals. This capability creates almost unlimited possibilities for improved control of mobile vehicles, ranging from simple remote control of the pump swashplate to sophisticated automatic control. This paper discusses the more practical types, including steering, crossover control (pump/motor phasing), engine anti-stall control, pressure override, and constant-speed control.

Earlier transmissions were equipped with a complex mechanical linkage for actuating the dual power planetary gear set. Field experience revealed the need for a reliable, simplified and less expensive method for this particular transmission control. An electrohydraulic directional control valve was developed to provide an economical design improvement which was readily incorporated into present models.

High pressure, load sensing valves, like the Vickers actuator mounted CMX valves, demonstrate significant advancement in performance and efficiency with the adaptation of electrohydraulic pilot controls. Electrohydraulic feature provides increased operator comfort, simplified plumbing, improved control properties and adaption to microprocessor electronics on mobile systems.

Valve-controlled hydraulic drives are frequently used when high dynamics, high reliability and a compact structural form are required. A disadvantage which is frequently attributed to a valve-controlled drive is its poor running efficiency. It not only leads to higher energy consumption but - amongst other things - to the necessity of installing larger pumps and more elaborate cooling equipment. Both these factors cause an increase in the costs of hydraulic drives. Load sensing is known from the field of mobile hydraulics as a driving concept with high running efficiency. In load sensing the supply pressure is adjusted to suit the actuator's highest point of load pressure. The dynamics of this system is worse than that of systems with a constant supply pressure. Electrohydraulic load sensing offers possibilities to improve the dynamics of valve-controlled drives in load sensing by using control engineering measures.

The electrohydraulic power steering (EHPS) system is a new approach to the supply of power steering to vehicles requiring supplementary assist. It may be used in vehicles where a standard engine-driven pump system cannot be packaged. An additional benefit is the ability of the system to shift to manual operation as a function of road speed. Such a shift to manual operation could be based on input signals from the driver as well. The unit as presently designed is most efficiently used in a vehicle with a front end weight of less than 600 KG (1320 lbs.). However, if upsizing of the system should be required, the overall package has been designed with this option in mind. The electrohydraulic power steering system is designed in a modular format. The pump package consists of an electronic controller, motor, pump, and reservoir, attached to a main bracket. A unique hydraulic fluid is utilized to allow adequate performance over a wide temperature range.

The results from an investigation of some of the effects of using a linearized model for prediction of the behavior of a nonlinear system are presented. The system studied is a velocity system using an electrohydraulic servoactuator to drive an inertial load. Both nonlinear and linearized system models are defined. The result of defining optimal feedback values for an integral quadratic performance index is shown along with the effect of choice of nominal operating point on the linearized system transient response. Finally, linear and nonlinear transient responses are compared for a range of step amplitudes.

An accurate nonlinear model of a typical magnetic actuator is included in a new SPICE simulation of an electrohydraulic system. The actuator model is obtained by electromagnetic finite element analysis. The resulting nonlinear magnetic flux linkages and forces as functions of airgaps and currents are included in the SPICE model. The SPICE model is able to include electronic driver circuits and models of the hydraulic circuits, which are shown to interact to determine the closing time of electrohydraulic valves.

The use of mechanical, electrical, electronic, computer, and control engineering concepts combined in a particular machine or process is occurring at an increasingly rapid pace. The integration of these concepts is referred to as mechatronics. Engineers and technicians now must have knowledge and skills in all of the areas mentioned. Mobile machines have always incorporated knowledge from a variety of areas as needed to incorporate desired features and work functions. However, the time has come to make a more formal recognition of this integration of ideas.

One way to improve diesel engine performance and to reduce emissions is improving power density and combustion cycle efficiency. It can be done by increasing combustion pressure and engine speed drastically and also by improving the controllability of the engine. Besides of the fuel injection system the key element in improving controllability is the valvetrain. Extreme combustion pressure and engine speed set special requirements for valvetrain design. As the pressure and engine speed are increased the load on the valve actuation mechanism becomes higher because of the higher pressure acting on the valve plate and also the need for higher acceleration. High instantaneous power required due to high load makes electrohydraulic system a natural choice for actuation mechanism. An electrohydraulic camless valvetrain (IHAflex) for extreme value engine (EVE), developed by Institute of Hydraulics and Automation of Tampere University of Technology, uses neither cams, nor retainer springs.

This article reports on the effects of various types of high field electrical phenomena imposed on low load lean combustion in a spark ignition petrol engine. The first part of the work deals with purely electrical field effects with no induced ionization. An electric field was applied via an insulated static high voltage DC electrode (up to 15 kv) which does induce excess charge effects, near the spark source. This was found to have very modest effects on the imep and its cyclic variability, which are unlikely to be significant enough to warrant commercial development. Further work reported here concerns the testing of an electrohydrodynamic device formed from a modified spark plug. This was operated in a test chamber under typical pre-combustion pressures where it was possible to obtain corona flows up to 10 m/s.

The Electroimpact Automatic Fan Cowl Riveter exhibits new and unique design features and automated process capabilities that address and overcome three primary technical challenges. The first challenge is satisfying the customer-driven requirement to access the entire fastening area of the fan cowl doors. This necessitates a unique machine design which is capable of fitting ‘inside’ a fan cowl door radius. The second challenge is determining drill geometry and drill process parameters which can produce consistent and high-quality countersunk holes in varying mixed-metal stack-up combinations consisting of aluminum, titanium, and stainless steel. The third challenge is providing the capability of fully automatic wet installation of hollow-ended titanium rivets.

Characteristics of electroless nickel plating which have provided advantageous application in aircraft maintenance operations have included high throwing power resulting in uniform coverage of partially blind areas, close dimensional tolerance control, high hardness controllable by heat treatment to provide good wear resistance and good corrosion protection. More recently, it has been shown that modern high phosphorous coatings provide improved adherence and strength which severely limited application of earlier electroless nickel coatings. The process has now been approved by an engine manufacturer for optional replacement of electrolytic nickel plating for diffused nickel-cadmium coatings on selected parts. It is the purpose of this paper to review some of the current applications and consider potential new uses for this process.

A metallic matrix composite coating has been developed that imparts unique surface properties to a wide range of metallic substrates. The coating, based upon conventional electroless nickel technology, incorporates sub-micron particles of PTFE distributed uniformly throughout the coating thickness. The presence of the PTFE provides a continuous reservoir of lubricating particles giving a low friction surface that is accurate over the most complex components and that has many potential aerospace applications.

From failure to success in developing a direct sunlight readable electroluminescent display for use in general aviation cockpits. Initial attempts using existing technologies resulted in failure of a product design. Using new EL driver design approaches a 76.2 mm x 127 mm EL display with an unfiltered average brightness of 65 foot lamberts (1) was developed which proved to be satisfactory across the range of dark night to bright day sunlight ambient lighting conditions within an aircraft cockpit. A circular polarized contrast enhancement filter was developed for the EL display. Although the filter lowered the average brightness to 24 foot lamberts the overall readability was increased. EL displays may be a good alternative to other technologies for use in direct sunlight applications.

A pilot plant facility has now been established to build DC electrolumescent panels. A new product is being made which combines analogue and digital readouts on one panel. Any panel up to 6″ × 18″ can be made due to the process simplicity which consists largely of screen printing techniques. The pilot product is 2″ × 7″ and displays are made six at a time. A combination of custom designed I.C.'s and microprocessor drive can be used to provide full, flexible solid state instrumentation.

Lithium-ion rechargeable batteries have been demonstrated to have high energy density, high voltage, and excellent cycle life which make this technology more attractive than competing systems such as Ni-Cd and Ni-H2. However, the SOA cells fail to meet certain requirements necessary for various future NASA missions, such as good low temperature performance. Under a program sponsored by the Mars Exploration Program we have developed an organic non-aqueous electrolyte which has been demonstrated to result in improved low temperature performance of lithium-ion cells. The electrolyte formulation which has resulted in excellent low temperature performance, as well as good cycle life performance at both ambient and low temperatures, consists of a 1.0M solution of a lithium salt, lithium hexafluoro-phosphate (LiPF6), dissolved in a mixture of carbonates: ethylene carbonate + dimethyl carbonate + diethyl carbonate (1:1:1).

The electrolytic liquid display is a new passive particularly designed for automotive applications. It looks like liquid crystal display but operates on a completely different way by electrolysis phenomenous. A small current at low voltage produces the transfer of silver from a back glass where silver is not visible to the front glass where the thin layer of silver obtained gives a black surface. This type of display fulfil almost all the requirements of automotive uses such as temperature operating range, viewing angle, shocks and vibrations. Their manufacture operations are cheaper than those for liquid crystal and must finally give a lower manufacturing cost. At last one particularity is its memory effect which may be in some cases an advantage.