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Cylinder deactivation is a proven solution to improve vehicle fuel economy. This proposal presents Dynamic Cylinder Deactivation (DCD) solution to the conventional automotive engines. DCD is an engine cylinder deactivation solution based on engine thermodynamics and residual heat recovery. It is an innovative solution toward engine fuel conversion efficiency, totally different from traditional sealed-valves cylinder deactivation solutions. DCD has many advantages over traditional sealed-valves cylinder deactivation. Thermodynamic efficiency gain and residual heat recovery are the most attractive features from DCD advantages.

In this DCD proposal, method and theory of DCD with residual heat recovery are presented. Thermodynamic analysis is made to demonstrate the benefits of DCD and its related residual heat recovery. Electronic implementation is completed by microcontroller based control module. A top level electronic design is proposed, with multiple automotive grade devices from Infineon being applied into the control module. A thorough comparison between the proposed DCD and traditional sealed-valves cylinder deactivation is also presented.

This proposal presents Dynamic Cylinder Deactivation (DCD) solution to the conventional automotive engines. DCD is an engine cylinder deactivation solution based on engine thermodynamics and residual heat recovery. It is an innovative solution toward engine fuel conversion efficiency, totally different from traditional sealed-valves cylinder deactivation solutions.

Traditional sealed-valves cylinder deactivation solutions began in 1980s ^[1]. It deactivates partial engine cylinders in a fixed pattern to reduce pumping loss, thus helps to increase engine fuel conversion efficiency. The big problem is it causes heavy engine thermal unbalance, with the deactivated cylinders being cooler than normal and the active cylinders being hotter than normal due to heavier unit cylinder load. As a result, the cooler deactivated cylinders will suffer from reduced lubrication and thermodynamic loss, as well as larger friction, mechanical worn-out and gas blow-out; while the hotter active cylinders will trend to knock and generate NOx emissions.

DCD deactivates all the cylinders inside the engine dynamically and in a balanced way. That is, all the cylinders inside the engine will be working in an intermittent mode, being activated and deactivated alternatively. The result would be not only a well balanced engine thermal condition under which engine performance could become the best, but also the residual heat recovery by engine thermodynamic expansion during the deactivation cycles. Based on all of these benefits, we could expect DCD would bring us higher engine fuel conversion efficiency than traditional sealed-valves cylinder deactivation.

Energy conservation is the best way to solve energy problem. Increase engine fuel conversion efficiency is an effective way to implement energy conservation. Most motor vehicles require fossil fuel as energy source. In US, motor vehicles consume 69% of fossil fuel energy. It is believed that much of benefit would come from fuel efficiency improvement. A 10% efficiency improvement in vehicle performance would save over $82 billion US dollars per year to import foreign oil based on the current $120 crude oil price, and reduce emissions of carbon dioxide by 171 million metric tons per year.

Cylinder deactivation is a proven solution to save fuel. It has been adapted by majority of automobile manufacturers. General Motors’ cylinder deactivation solution is called Active Fuel Management (AFM). It gives a 6% to 8% improvement in fuel economy ^[2]. DaimlerChrysler’s cylinder deactivation solution is called Multi-Displacement System (MDS). It claims that fuel economy will boosted by 10% to 20% ^[3]. Mercedes-Benz’s solution is called Active Cylinder Control (ACC) ^[4], it was applied to its V12 engine only. Mitsubishi also had MD System (Modulated Displacement) ^[1] in 1982 based on its 4-cylinder engine. Honda’s solution is Variable Cylinder Management (VCM) ^[5]. Facing the current $120 crude oil price, more and more vehicles have been and will be integrated with cylinder deactivation solution.

All of the above solutions are referred as traditional cylinder deactivation solutions. They all utilize the method of disabling and sealing the valves of the cylinder to be deactivated. Normally they are implemented mechanically by hydraulic or electromagnetic valve actuation controls.

To automobile consumers and vehicle drivers, the benefits of cylinder deactivation is simply reduced fuel consumption and improved fuel economy. It also helps to reduce engine emissions and CO2 discharge. Saving fuel means energy conservation, which will help to solve energy problem and ease the crude oil price. It also has positive contribution to the public society by reducing global warming and greenhouse effects.

As will be seen below, DCD would have even more benefits than traditional sealed-valves cylinder deactivation.