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valve idea

Posted by ReubenT 
valve idea
January 20, 2016 03:48AM
I have this idea for a rotary steam valve where no seals are needed, lube provided with lube ports and oil continually delivered like it is with engine bearings, wear self adjusted for. Could be used either continual rotation with fixed cutoff determined by width of steam ports, or back and forth operation with variable cutoff, linkage arranged sort of like the corliss valve linkage operated so it would have fixed opening and variable closure. Although that would limit speed. Continual rotation be better for higher speed application, but would have to control engine speed with separate throttle valve. And would be simplest to drive with timing belt or roller chain. One valve easily delivering to multiple cylinders. Only issue there is passage length from valve to cylinders increasing the size of compression chamber. Shorter cutoff may partially compensate for that. Very simple to machine. I intend to try it as soon as I can. But with too much going on it may be awhile before I can get to it. Need to finish my boiler first so I have steam to work with. I'm thinking use such a valve for inlet on IC engine and built in poppets for exhaust. Or it could work just as well for old style double acting engine, especially with the variable cutoff arrangement. however in such mode it would be limited to one cylinder per valve, preferably two valve per cy so they could be right on the head of each side with no steam lost to port length. And an IC engine style poppit valve in each head for exhaust. I would present a drawing but I never did such things on a computer. Don't know how.
Re: valve idea
January 20, 2016 12:36PM
Reuben-

Congrats to you-hopefully you will succeed where others have failed! A rotary valve design that solved the lubrication/thermal stress/wear issues would be a real game changer.

Keep us informed-a new valve idea would solve a lot of problems!


Chuk
Re: valve idea
January 21, 2016 02:05PM
The point that seems to have escaped everyone is that the prime goal today is to eliminate any oil in the steam. One only hopes that Mazda has indeed developed oil free seal material for their new Wankel engines.This development is being closely watched.
Piston ring seals in single acting steam engines is a serious source of leakage and oil contamination.
Carbon formation in the steam generator, coating the condenser surfaces, the need to keep the superheat below the point where it burns and forms carbon, are the serious problems with using oil.

Rotary valves require copious lubrication, leak severely in both axial and circumferential directions, have ultra short distances from the inlet port to the exhaust port in disk valves unless unaflow, are notorious for seizing and have a high wear rate unless flooded with oil.
Rotary valves were offered over a hundred ten years ago in steam engines and unless used with very low pressure and wet steam, were total failures. They do not work with high superheat steam.
Several two cycle motorcycles used disk intake valves and BMW made a Wankel designed V-8 torpedo engine in WW-II that used them, with obviously a very short life.
For modern vehicle use, only the balanced poppet valve is seen as optimum.
Jim
Re: valve idea
January 22, 2016 12:28AM
for those reasons it may not work, but it'd be so simple to make I might as well try it. I wonder if anyone tried MBL with them. Also wondering if anyone has tried an aircraft style lube system (modified) for engines to get the water settled before it's pumped through again. If a balanced poppet is the best for it, how about designing one that will be relatively easy for a home machinist with manual machines to make. The only thing I can visualize requires packing to seal the stem and custom double flange valves. Not real complicated but pretty time consuming to create several of them for a multi cy engine. Identical to the balanced throttle valve used under governors in old steam engines.
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