A sample from page 1: - Back to the EVIC book

The EVIC was born out of my 1999 experiments with electronic intake valve control on my Experimental 2 Cylinder 2 Stroke Engine and out of experiments with electronic ignition modules with a programmable speed advance. These two sets of experiments gave me the confidence to tackle this project. The engine name comes from Electronic Valves Internal Combustion 1 cylinder, 1" bore and 1"stroke.

Design started in November 1999 with the idea of demonstrating the engine at NAMES in April. The limited time forced a simple design and an easy to build engine. The goal was met, just barely. The first really successful run was April 20, just 9 days before the show.

Typical 4 stroke cycle engines have fixed intake and exhaust valve timing. The designer chooses the timing to achieve certain performance goals. Once the valve cams are designed the timing is fixed unless major mechanical changes are made. Recently some automotive engines have implemented a form of variable valve timing to good advantage using techniques that move or vary the camshaft position. These techniques allow only a limited change in valve timing.

Electronic controls offer the possibility of almost unlimited variations in valve timing. There are many challenges in designing electronic circuits and controls that can operate the valves at the high speeds required for an internal combustion engine. However today's micro computers are capable of implementing algorithms that can open or close the valves at just the right time. My 1999 experiments with electronically controlled intake valves on my experimental 2 cylinder 2 stroke engine demonstrated that solenoids could operate the valves. .....

Determining how much force is required to open the valves proved to be a challenge. My first thought was that all I needed was enough force to quickly open the valve against the force from the valve spring. This is indeed the case for the intake valve because the cylinder pressure is at or near atmospheric when this valve opens. But the exhaust valve is a different story.

The exhaust valve must open while there is still considerable pressure in the cylinder. This pressure pushes on the face of the exhaust valve with a force equal to the cylinder pressure times the face area of the exhaust valve. The area is easily calculated from the formula:

With the help of several model engineers I was led to the idealize p (pressure) V (volume) diagram for a gasoline engine. Although none of the examples I found provided real world data we eventually determined that the exhaust gas temperature should be between 400 and 800°C. This led to the conclusion that the cylinder pressure should be about 3 atmospheres or 45psi at the time the exhaust valve should open. Therefore the solenoid force had to be 1/8 (actually 0.1256) of this value or about 6 pounds when you add the spring force. How do you get 6 pounds of force from a solenoid designed to provide a few ounces without burning it up? Modern day electronics provided the answer.

A small solenoid can produce a large force if enough electrical power can be provided. However the application of this power must be controlled and limited or the solenoid will overheat and fail. The PIC micro computer combined with power MOSFET transistors provided the answer. The micro limits the application of power to just enough time to force the exhaust valve open. ....

Back to the EVIC book

Contact Info : dbowes12@cogeco.ca