1 Steam Cars : Phorum
General Steam Car topics
A dream of barrel valves
Posted by: Garry Hunsaker (IP Logged)
Date: March 26, 2002 04:52PM
<HTML>Or was that a ngihtmare???
Ok, this is something that floated into my grey matter in that time between being asleep and not really awake. So it means somebody back about 1830 already thought this idea up, and there are probably major problems with it.
I haven’t set down to sketch this out, but I thought it would be better to get it down in some form before my mind sends it to that lost items file folder in my brain. I decided to subject all of you too it, because of Jim’s work on the Wankel interests me.
This is another rotary valve. To visualize this, just think of a small tin can that is open on one end with a shaft attached to the center of the closed end. This ‘barrel’ has a pair of holes drilled in opposite sides, that will line up with steam inlets in its circumference. I assume this is suppose to balance the side loads on the valve. There are also a set of small holes drilled in the bottom of the can, more on those in a moment.
Steam enters the ports by matching opposite inlets on the external circumference of the valve. Apparently as some kind of back up, and sealing the major circumference of the valve are a set of ‘lap ended’ piston rings on the barrel between the inlet ports and the engines cylinder. Sealing the ports themselves were a set of tube shaped rings, whose ends were ground to match the face of the valve. These were installed with light springs under them to hold them in contact with the valve. These ‘rings’ and springs were installed externally through the inlet ports, and were held in place by the fittings that the steam lines are attached.
At the base of the barrel, where those small holes are, and the valve stem extends outside of the valve, is what looked like a small flat timkin thrust bearing. To keep this bearing alive, the cylinder oil was injected near the outer circumference of the bearing. Those small holes in the base of the barrel avowed the cylinder oil to then enter into the center of the barrel, and hopefully around the outside of it at least a bit.
I can see several possible problems with this idea.
One the cylinder that holds the inlet ports would be very hot on two sides, which is not much help in keeping its bore perfectly round, though I am not sure that would really matter if those tube rings did their job, the barrel would not have to fit that tightly in its bore. Ahh... I wonder if that was the reason for those extra rings on the outside of the barrel, to act as bearing & sealing surfaces?
I suppose it would be possible to incase the entire valve in live steam. It would then be necessary to provide openings in the side of this steam chamber to access those tubular ‘rings’. One thing this would do is it might be possible to add a second set of opposing ports 90% our of alignment to the first set. Lets see.. If I got this right, that would mean the valve would be moving at one quarter the speed of the crank on a standard piston engine. I really need to sketch this out, this is starting to make my head hurt. :)
The one thing in this whole dream that has me going huh, is that small flat timkin thrust bearing. There is a good part of me that is going, you have to be kidding. That wont survive for ten hours of running.
Then there is also the question of all that dead steam space this valve would add. Though on a unaflow....
Well, I could probably rattle on about his for another three or four pages, but if anyone can build a usable ‘steam car valve’ out of this, more power to you.
Garry Hunsaker</HTML>
Ok, this is something that floated into my grey matter in that time between being asleep and not really awake. So it means somebody back about 1830 already thought this idea up, and there are probably major problems with it.
I haven’t set down to sketch this out, but I thought it would be better to get it down in some form before my mind sends it to that lost items file folder in my brain. I decided to subject all of you too it, because of Jim’s work on the Wankel interests me.
This is another rotary valve. To visualize this, just think of a small tin can that is open on one end with a shaft attached to the center of the closed end. This ‘barrel’ has a pair of holes drilled in opposite sides, that will line up with steam inlets in its circumference. I assume this is suppose to balance the side loads on the valve. There are also a set of small holes drilled in the bottom of the can, more on those in a moment.
Steam enters the ports by matching opposite inlets on the external circumference of the valve. Apparently as some kind of back up, and sealing the major circumference of the valve are a set of ‘lap ended’ piston rings on the barrel between the inlet ports and the engines cylinder. Sealing the ports themselves were a set of tube shaped rings, whose ends were ground to match the face of the valve. These were installed with light springs under them to hold them in contact with the valve. These ‘rings’ and springs were installed externally through the inlet ports, and were held in place by the fittings that the steam lines are attached.
At the base of the barrel, where those small holes are, and the valve stem extends outside of the valve, is what looked like a small flat timkin thrust bearing. To keep this bearing alive, the cylinder oil was injected near the outer circumference of the bearing. Those small holes in the base of the barrel avowed the cylinder oil to then enter into the center of the barrel, and hopefully around the outside of it at least a bit.
I can see several possible problems with this idea.
One the cylinder that holds the inlet ports would be very hot on two sides, which is not much help in keeping its bore perfectly round, though I am not sure that would really matter if those tube rings did their job, the barrel would not have to fit that tightly in its bore. Ahh... I wonder if that was the reason for those extra rings on the outside of the barrel, to act as bearing & sealing surfaces?
I suppose it would be possible to incase the entire valve in live steam. It would then be necessary to provide openings in the side of this steam chamber to access those tubular ‘rings’. One thing this would do is it might be possible to add a second set of opposing ports 90% our of alignment to the first set. Lets see.. If I got this right, that would mean the valve would be moving at one quarter the speed of the crank on a standard piston engine. I really need to sketch this out, this is starting to make my head hurt. :)
The one thing in this whole dream that has me going huh, is that small flat timkin thrust bearing. There is a good part of me that is going, you have to be kidding. That wont survive for ten hours of running.
Then there is also the question of all that dead steam space this valve would add. Though on a unaflow....
Well, I could probably rattle on about his for another three or four pages, but if anyone can build a usable ‘steam car valve’ out of this, more power to you.
Garry Hunsaker</HTML>
Re: A dream of barrel valves
Posted by: Peter Brow (IP Logged)
Date: March 27, 2002 10:02AM
<HTML>Hi Garry,
Sounds better than most rotary valves. The sealing rings could be loaded by working-fluid (steam) pressure, like the rings in Coates valves. The thrust bearing could go outboard, away from heat, along with bearings to keep the drive shaft from tilting, and an extension on piston crown could go into the center of the barrel valve to cut clearance -- if it were a sort of rotating sleeve valve. Machining the rings might be tricky, but maybe if cut right and lapped to valve, it might work out. If rotating, no worries about rpm, the inlet ports on opposite sides for balance seem a good idea. Maybe opposed exhaust ports could be built into the same valves -- in a different plane -- to make it a counterfow.
Cutoff control, not sure. Maybe several tracks for staged ports, along the rotary axis of valve, which are valved on or off to control cutoff. For short cutoff, only one port receives steam, for a bit longer, 2, for max cutoff, 3. 2-3 cutoff levels are fine with good design -- long admission for low speeds and/or self-starting, short for higher speeds. Reverse if desired. Longer cutoffs would have longer ports along the perimeter of the valve. I tried to use a similar principle in disk valves. Or just use one cutoff and gear reverse.
Rotary valves tend to leak badly, but some (eg RJ Smith) have reportedly run well in a steam-hoggish way with plenty of oil. Differential heat expansion of stationary and rotating mating elements is the main culprit in leakage -- matching grooves and lands (on the microscale) don't line up when hot. Might just need a bigger boiler & more fuel/water consumption than a tighter engine, and this would limit power & range, but for a fun hobby vehicle who really cares. Lots of the "super advanced high efficiency" attempts, with a fortune invested in them, didn't do too well either due to unforeseen factors.
Also, rotary valve leak problems are mainly with high-temp high-pressure superheated steam. With saturated or nearly saturated steam, semi-rotary Corliss valves work extremely well, and a full-rotary version might be okay too (bring the Corliss full circle). Of course boiler size & fuel consumption are automatically higher with saturated steam, and performance is not as snappy, but it might end up the same as a leaky rotary valve with superheated steam. Before anybody scoffs, I should emphasize that this is for a low-budget EZ-build fun machine only, not a speed record or consumer/EPA-pleaser car.
But some superheat experiments might be interesting, never know for sure until you try.
Even a homebuilt steamer running at 5 mpg (or solid fuel) & 20-30 mph on back streets or off road, would be fun. A recent episode of the TV show "Junkyard Wars" had 2 teams competing to install saturated steam engines & coal boilers in junk cars in a few hours, and they got 'em running at like 10-20 mph for a race, looked like a blast. With a little effort, almost anything could run better than that.
Peter</HTML>
Sounds better than most rotary valves. The sealing rings could be loaded by working-fluid (steam) pressure, like the rings in Coates valves. The thrust bearing could go outboard, away from heat, along with bearings to keep the drive shaft from tilting, and an extension on piston crown could go into the center of the barrel valve to cut clearance -- if it were a sort of rotating sleeve valve. Machining the rings might be tricky, but maybe if cut right and lapped to valve, it might work out. If rotating, no worries about rpm, the inlet ports on opposite sides for balance seem a good idea. Maybe opposed exhaust ports could be built into the same valves -- in a different plane -- to make it a counterfow.
Cutoff control, not sure. Maybe several tracks for staged ports, along the rotary axis of valve, which are valved on or off to control cutoff. For short cutoff, only one port receives steam, for a bit longer, 2, for max cutoff, 3. 2-3 cutoff levels are fine with good design -- long admission for low speeds and/or self-starting, short for higher speeds. Reverse if desired. Longer cutoffs would have longer ports along the perimeter of the valve. I tried to use a similar principle in disk valves. Or just use one cutoff and gear reverse.
Rotary valves tend to leak badly, but some (eg RJ Smith) have reportedly run well in a steam-hoggish way with plenty of oil. Differential heat expansion of stationary and rotating mating elements is the main culprit in leakage -- matching grooves and lands (on the microscale) don't line up when hot. Might just need a bigger boiler & more fuel/water consumption than a tighter engine, and this would limit power & range, but for a fun hobby vehicle who really cares. Lots of the "super advanced high efficiency" attempts, with a fortune invested in them, didn't do too well either due to unforeseen factors.
Also, rotary valve leak problems are mainly with high-temp high-pressure superheated steam. With saturated or nearly saturated steam, semi-rotary Corliss valves work extremely well, and a full-rotary version might be okay too (bring the Corliss full circle). Of course boiler size & fuel consumption are automatically higher with saturated steam, and performance is not as snappy, but it might end up the same as a leaky rotary valve with superheated steam. Before anybody scoffs, I should emphasize that this is for a low-budget EZ-build fun machine only, not a speed record or consumer/EPA-pleaser car.
But some superheat experiments might be interesting, never know for sure until you try.
Even a homebuilt steamer running at 5 mpg (or solid fuel) & 20-30 mph on back streets or off road, would be fun. A recent episode of the TV show "Junkyard Wars" had 2 teams competing to install saturated steam engines & coal boilers in junk cars in a few hours, and they got 'em running at like 10-20 mph for a race, looked like a blast. With a little effort, almost anything could run better than that.
Peter</HTML>
Re: valves leakage
Posted by: C Benson (IP Logged)
Date: March 27, 2002 10:33PM
<HTML>Leakage of superheat steam will cut cast iron an' leave a crystaline surface looking as if it were a break,,,,really funney looking ,,,I have seen it,,,,can anyone explain this fenomina,,,I wasnt expecting the surface to look like that,,It did not exhibit the appearence of a oil failure,,,just leakage,,,,Cheers Ben</HTML>
Re: valves leakage
Posted by: Peter Brow (IP Logged)
Date: March 28, 2002 08:29AM
<HTML>Hi Ben,
No practical experience with this (yet), but I have heard of "cutting" from superheated steam leaks, also references to a "scouring effect". Maybe this is a (the?) factor in rotary valve leaks. Reportedly Stanley and other throttles are designed to minimize this, by throttling the steam at a point separate from shutoff. An explanation from steam theoreticians would be interesting.
About the closest to this I've seen is slow faucet leaks cutting grooves in valve seats.
Peter</HTML>
No practical experience with this (yet), but I have heard of "cutting" from superheated steam leaks, also references to a "scouring effect". Maybe this is a (the?) factor in rotary valve leaks. Reportedly Stanley and other throttles are designed to minimize this, by throttling the steam at a point separate from shutoff. An explanation from steam theoreticians would be interesting.
About the closest to this I've seen is slow faucet leaks cutting grooves in valve seats.
Peter</HTML>
Re: A dream of barrel valves
Posted by: David K. Nergaard (IP Logged)
Date: March 28, 2002 11:16AM
<HTML>SES bought the patent rights to a rotary valve in 1969 and spend some time and money trying to make it go. It worked fine while it lasted, but that was a matter of minutes, not hours let alone years. They quickly shifted to using poppet valves as superheated steam was essential to get anything like the efficiency required.</HTML>
Re: A dream of barrel valves
Posted by: Garry Hunsaker (IP Logged)
Date: March 28, 2002 07:58PM
<HTML>Thanks for the input on rotory valves gentlemen. When you start looking at high pressure, high temperature steam, things get intersting.
Garry</HTML>
Garry</HTML>
Sorry, only registered users may post in this forum.