gcdugas wrote:

n smikle wrote:

gcdugas wrote:The intake and exhaust gain nothing from being independent.

The exhaust valve is very hot so that means that if the exhaust and intake valve is one and the same then you have a hot intake valve.

The piston crown and the cylinder walls are all heated by the exhaust gases and cooled by the intake charge. So what?

So what is nowhere near a suitable question. The effect of this heat transfer from exhaust port to inlet charge are major and complex. Serious reductions in cylinder filling is just one.

autogyro wrote:So what is nowhere near a suitable question. The effect of this heat transfer from exhaust port to inlet charge are major and complex. Serious reductions in cylinder filling is just one.

We are having a general discussion of various engine schemes. If one were to describe a conventional F1 V8 the objections would be... high reciprocating mass, inefficient pumping due to valve size and opening limitations, high mechanical losses, high CG due to cylinder head design, etc. Benefits would be ideal combustion chamber shape, ideal spark plug location, poppet valve sealing is augmented during combustion pressures etc. Similarly if one were to describe a conventional turbine engine the objections would be centered around its inability to rapidly change RPM levels and throttle response. A two stroke might be objected to on the grounds of lubrication and emissions.

It is the nature of these general conceptual discussions to say "so what". A jet aircraft doesn't need instantaneous throttle response and is happy running at a constant RPM. It also works very well in the freezing temperatures of the upper atmosphere. A air plane designer says "so what" to throttle response. A spark ignition designer says "so what" to the complexity of an ignition circuit system. We are talking about whole categories of limitations in each scheme. Objections and dismissals are necessarily embraced once you go down a given path. A diesel designer embraces the benefit of needing spark plugs and ignition coils however he inherits other limitations. We are making categorical choices here.

Simply put, "serious reductions in cylinder filling" is not a concern. In the BRV engine, the intake charge encounters the "hot thin wall" of the mutual valve very late in the sequence of events and has about as much effect on the charge filling and temperature as does the intake charges encounter with the piston crown and cylinder walls. A non intercooled turbo on the other and greatly effects these things because the intake is heated (by the compressing turbo) very early in the sequence of things.

The gains in pumping (cylinder filling) and having no reciprocating mass are significant enough to say "so what" when comparing them to nominal losses due to a little (very little) heat during cylinder filling.

Valve sealing, combustion chamber shape, spark plug location are all much more challenging to overcome than your negligible heat issue. And from what we have all read, it seems that these concerns have been effectively addressed in the lab.

The other problems you mention are not nearly as difficult to cure.A red hot rotating valve is not a negligible issue.
To prevent this the mixture has to be continually rich, resulting in low fuel efficiency and unacceptable exhaust emissions. Worse even than for a rotary engine.
The excuse of finely simulating mixture turbulence, is to try to burn this rich mixture more than anything else.

An overview of 16 rotary valve developements; 1909>2001
http://www.dself.dsl.pipex.com/MUSEUM/P ... alveIC.htm
I believe one of our forum members held a patent on a rotary valve engine, I remember reading through the abstract and the illustrations, as it was mentioned in a thread, a search of the forum will offer more details. I very much admired the design and have always enjoyed reading the author/patentholder's posts.

gcdugas wrote:

n smikle wrote:

gcdugas wrote:The intake and exhaust gain nothing from being independent.

The exhaust valve is very hot so that means that if the exhaust and intake valve is one and the same then you have a hot intake valve.

autogyro wrote:The main problem in the Bishop valve is the heat from the exhaust port in the rotary valve transferring to the inlet port through the uncooled thin wall.

The piston crown and the cylinder walls are all heated by the exhaust gases and cooled by the intake charge. So what? The pumping gains are well worth it and the mechanical gains from having no reciprocating mass in the valve train are worth it. I still can't find the sparkplug location.

At the top corner of the cylinder I guess.
THat BRV can probably be coated with something. Maybe something very reflective on the exhaust side.. It's still going to be hot though. I can't say how much heat transfer to the intake charge though.

My other concerns are just the sparkplug location and the over dependency of one valve on the other (intake and exhaust can't be adjusted independently. In F1 dependency between the valves probably doesn't matter that much anyway because of the rules.. but it is good if the system is flexible so you can apply it to road cars. oh yeah.. you will loose valve overlap with that design too.. that is another thing.

Effective cylinder filling is to a great extent reliant on valve overlap and duration, which cannot be completely duplicated with both ports/valves in one unit.

autogyro wrote:Effective cylinder filling is to a great extent reliant on valve overlap and duration, which cannot be completely duplicated with both ports/valves in one unit.

I would heartily disagree. I have extensively studied single, bifurcated, axial/radial flow rotary valves for high speed 4-stroke racing engines. And I have a US patent (#5,052,349) on just such a design. Coincidently(?), it is very similar to the Ilmor/Bishop F1 design, and my patent predates theirs by several years. But my patent was only valid in the US, so maybe that's why the Ilmor/Bishop development work was all conducted in Europe.

http://www.google.com/patents?id=TT8gAA ... q=&f=false

I never built a running engine using the design (due to lack of money), but I did lots of flow bench and modeling work with it. What I found was that my single rotary valve had far superior port-time characteristics (due to the more aggressive opening and closing flow areas possible with a fixed speed rotary valve versus a less aggressive cam-driven, reciprocating poppet valve flow), higher mean flow coefficients, better scavenging characteristics, much greater max flow areas possible with a single rotary valve port versus the typical 4-valve poppet head, and less "short circuiting" of intake/exhaust flows during timing overlap due to the tangential, swirling intake flow vectors inherent in the axial/radial porting geometry of the rotary valve. The rapid opening/closing effect of the rotary valve also produced a more intense intake/exhaust flow acoustic signature, which resulted in more power from intake/exhaust manifold tuning.

My rotary valve design also had no valvetrain operating frequency limit, like a poppet valve system has. And it also resulted in a much more compact cylinder head package than a poppet valve/spring/camshaft system. So it had lots of promise for a racing engine application, like in F1. But alas, I didn't have the money to pursue its development. And my patents have now since expired, so anyone is free to use it. And you will have my blessing to do so.

I spent way more money on it than I should have. And in the end, I got nothing from all of my years of effort and tens-of-thousands of dollars spent, except heartache. But honestly, I'd probably do it all over again, because at the time it made me feel that I had a purpose in life.

Good luck.
Terry