University of Minho
Department of Mechanical Engineering
MIEMEC | Integradora VIII
Trapezoidal Rotary Valve
State of the Art
The trapezoidal valve system is subject to great interest because it combines the rotary valve system, which has been the focus of many studies during the past years, with the variation of the intake area. This is a huge improvement for the conventional engines due to the possibility of making them more fuel efficient, light weight, simpler in terms of maintenance and more powerful.
One of the big problems of the most conventional valve system, is its complexity and amount of components attached to it. In this system it is still necessary to use one or more cams to time the opening and closing of the valves and how much the valve opens, shown in figure 1. Comparing this aspect with the rotary valve, it is possible to see in figure 2 that it is much simpler to use and assemble. It is also possible to see that the cylinder head is smaller, which means higher pressure.
Figure 1. The different ways of assembling and using a poppet valve
Figure 2. Four-stroke engine with a rotary valve
In the past years, different types of rotary valves have been developed. One of these types uses two rotary valves, one for intake and another for outtake as shown in figure 3. This system is more complex than the system studied in this project because it uses two valves instead of only one for the intake and outtake.
Figure 3. Rotary valve system with two valves. The blue one for the intake and the purple one for the outtake
The system that most resembles the trapezoidal rotary valve is a system developed by Bishop Innovation in association with Ilmor Engineering. This system was meant to be used in Formula One V10 engines but then FIA banned completely this technology. This valve has the particularity of having only one valve per cylinder. The valve rotates at half engine speed and eliminates the inertia induced forces that have plagued the development of reciprocating poppet valve mechanisms since the invention of the internal combustion engine. As shown in figure 4, the valve incorporates the inlet (in blue) and exhaust (in red) port in the same valve.
Figure 4. Bishop rotary valve
As evident in the previous examples, the technology analysed in this project is innovative and constitutes a significant contribution to the automotive technology. The project also presents avenues for further research and technological improvements.