Waste Heat Recovery

Topics: Control theory, Control engineering, Control system Pages: 7 (1583 words) Published: December 27, 2012
Until the 1960s, the radio was the only significant electronics in an automobile.

All other functions were entirely mechanical or electrical, such as the starter motor and the battery charging systems. There were no “intelligent safety systems,” augmenting the bumper and structural members to protect occupants in case of accidents.

Seat belts, introduced in the early 1960s, were for improving occupant safety and actuated completely mechanically. The driver or one of several mechanical control systems controlled all the engine systems. For instance, before the introduction of sensors and microcontrollers, a mechanical distributor selected the specific spark plug to fire when the fuel-air mixture was compressed just so.

The timing of the ignition was the control variable. The mechanically controlled combustion process was not optimal in terms of fuel efficiency.

Modeling of the combustion process showed, for increased fuel efficiency, there existed an optimal time when the fuel should ignite.

The timing depends on load, speed, and other measurable quantities. The electronic ignition system was one of the first mechatronic systems to go in the automobile in the late 1970s.

The electronic ignition system consists of a crankshaft position sensor, camshaft position sensor, airflow rate, throttle position, rate of throttle- position-change sensors, and a dedicated microcontroller determining the timing of the spark plug firings.

Early implementations involved only a Hall Effect sensor to sense the position of the rotor in the distributor accurately. Subsequent implementations eliminated the distributor and directly controlled the firings utilizing a microprocessor.

Complex and highly accurate

The development of the microprocessor in the late 1960s led to early forms of computer control in process and product design. Examples include numerically controlled machines and aircraft control systems.

Yet the manufacturing processes were still entirely mechanical in nature, and the automation and control systems were implemented only as an afterthought.

The launch of the Sputnik and the advent of the Space Age provided yet another impetus to the continued development of controlled mechanical systems. Missiles and space probes necessitated the development of complex, highly accurate control systems.

Furthermore, the need to satellite mass while providing accurate control encouraged advancements in the important field of optimal control. Time domain methods and theories of optimal control matched well with the increasing availability of high-speed computers and new programming languages.

Advancements in semiconductor and integrated circuits manufacturing led to the development of a new class of products that incorporated mechanical and electronics in the system and required the two together for their functionality. Yasakawa Electric introduced the term mechatronics in 1969 to represent such systems. Yasakawa got the trademark in 1972, but after widespread usage of the term, released its trademark rights in 1982.

Initially, mechatronics referred to systems with only mechanical systems and electrical components—no computation was involved. Examples include the automatic sliding door, vending machines, and garage door openers.

In the late 1970s, the Japan Society for the Promotion of Machine Industry classified mechatronic products into four categories:

Class 1: Primarily mechanical products with electronics incorporated to enhance functionality. Examples include numerically controlled machine tool and variable speed drives in manufacturing machines.

Class 2: Traditional mechanical systems with significantly updated internal devices incorporating electronics. The external user interfaces are unaltered. Examples include the modern sewing machine and automated manufacturing systems.

Class 3: Systems that retain the functionality of the traditional mechanical system, but the internal...
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