SBIR-STTR Award

A program is proposed to analyze, design and test components for a system that will operate the valves of 4-cycle diesel and gasoline engines by means of hydraulic actuators, electronically controlled. The concept employs a feedback position transducer that provides a signal employed to compare actual valve displacement with a pro- grammed displacement and to make appropriate adjustments in the position of a hydraulic flow control valve so that engine valve travel achieved corresponds to travel desired. The desired opening program will be varied by selection from a range of such programs held in a microprocessor and accessed by combinations of operating conditions of the engine. These programs can include variable overlap settings that are selected by specific combinations of speed and load, transient response booster for turbocharged engines, complete cylinder shut down for idle on half the number of cylinders, zero overlap for cold starting, partial exhaust valve opening for improved engine braking and throttle elimination on spark ignited engines. Once the principle of operating in response to a memory held program has been realized, all these functions may follow merely by the programming process. A critical component in the proof of concept is the performance of the hydraulic control valve. For this reason a prototype of the valve will be detailed designed and fabricated. An existing in-house power supply will be employed to produce preliminary performance data on this unit.

A program was performed in Phase I that addressed the design and analysis of a variable valve timing system for IC engines. The objective of this system is to provide flexible timing, duration and overlap of inlet and exhaust valve events without increase in parasitic power. The benefits that can thereby be obtained are: I. No compromise between achieving maximum torque and maximum power. II. No compromise on settings to achieve stable idling and low exhaust emissions. III. Ability to accelerate a turbocharger to avoid turbo-lag by early exhaust valve opening. IV. Early inlet valve closure eliminates a throttle and thereby reduces pumping losses. The results of the computer study revealed a number of problems that have been addressed resulting in the design of a simpler system. Two smaller flow control valves, one catering for opening, the other for closing an engine valve, have been devised. These valves can readily achieve the displacement response required for satisfactory operation. Also revealed was a cavitation situation that prevented accurate motion control. This problem has been eliminated by the addition of two passive check valves. A displacement feedback transducer was eliminated and hydraulic pressure is maintained proportional to rpm(2). Thesis feature allows displacement to be controlled by timing the start of key events and programming the control valve displacement to a pre-set area/crank angle relationship. The program proposed addresses the design and fabrication of a single cylinder system that will initially be applied to an electric motor driven cylinder head rig. It will then be applied to a Petter AVILAB single cylinder diesel engine for performance tests.