Steam Actuated Inlet Valves?

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TriangleTom
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Steam Actuated Inlet Valves?

Post by TriangleTom » Sun Apr 08, 2018 9:12 pm

Would it be possible to actuate the opening and closing of valves directly by using steam?

Essentially, I'm thinking of a situation where a small amount of steam could be admitted to a small cylinder via a small solenoid. This steam would then force itself against the piston, which is attached to the main valvegear (presumably poppet), thereby opening the valve against the pressure of the steam and admitting steam into the much larger main engine cylinder.

It seems like this would be a good way to electronically control an engine while at the same time allowing very fast valve actuation, without the issues inherent in using much larger solenoids to control the admission directly. Presumably, because the advantages are mostly for the intake valve this would be best suited for a uniflow application.

I've done some research and so far I haven't been able to find any information about this having been tried in the past, although I'm sure I'm not the first person with this idea.
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Re: Steam Actuated Inlet Valves?

Post by Lionel Connell » Mon Apr 09, 2018 12:58 am

There are IC engines that use high pressure air or gas to open poppet valves using cylinders that are controlled with an engine management system. Trying to do this with steam could be done but it would make for a very elaborate system. Firstly the operating gas or steam needs to be up to pressure before the engine can be started. If using steam the plumbing for valve control system would need to be organized such the the steam is continually exhausted from every corner of the system to remove condensate and avoid hydraulic lock. If the valve control system fails while the engine is running at full speed it could lead to a major failure of the engine. The engine valve control cylinders need to be actuated by electronically controlled pilot valves which are generally quite small and so very high pressure compressed gas is usually used, 1000PSI or higher. Probably not the boiler pressure that you would like to run.

It would be far easier to use very large solenoids to directly open and/or close the inlet valves. In this case very short stroke balanced poppet valves would probably be the best candidate.

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Re: Steam Actuated Inlet Valves?

Post by dampfspieler » Mon Apr 09, 2018 6:31 am

Hi tom,
I've done some research and so far I haven't been able to find any information about this having been tried in the past, although I'm sure I'm not the first person with this idea.
a steam engine is a very tolerant system - it runs even with very poorly set valves. But the solution had to be simple - yours is difficult. Valves had to operated by incompressible media like steel ;) ;) .

If you are interested in variable valve-timing look for "Knaggen-Ventilsteuerung".

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Some interesting tweets you can find here (in german):
- Zwillings-Tandem-Verbundfördermaschine Zeche Radbod, Hamm
- Dampffördermaschine bauen

Such a system was also used by SENTINEL in their steam shunting locos.

Regards Dietrich
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Re: Steam Actuated Inlet Valves?

Post by RGSP » Mon Apr 09, 2018 8:13 am

Some "Southworth" style pumps have master-slave valve gear, where a mechanical linkage operate a pilot valve and steam pressure then shuttles the main steam valve. In this application the arrangement is mostly so that the pump never hangs between up and down strokes, and Southworth pumps are usually sized to run very slowly - strokes per minute very often - much slower than most steam engines producing power via a shaft.

All the same, the arrangement is similar in some ways to having a master-slave solenoid and steam shuttle valve.
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Re: Steam Actuated Inlet Valves?

Post by Lopez Mike » Mon Apr 09, 2018 3:51 pm

And why would anyone want to share a launch with such an engine? You might as well inject a light oil into the cylinder and let the heat of compression ignite it. Dispense with the heavy and wasteful boiler. It is a very well developed technology, poppet valves and all. Horrid too.
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Re: Steam Actuated Inlet Valves?

Post by Oilking » Mon Apr 09, 2018 4:26 pm

In this application the arrangement is mostly so that the pump never hangs between up and down strokes,
My experience on a Fletcher Class destroyer with Worthington vertical pumps, that had free piston main valves, was often one of frustration. Not if, but when the main valve hung-up the only way to restore operation was to whack it with a 4lb hammer since there wasn't external means to move the valve.

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Re: Steam Actuated Inlet Valves?

Post by DetroiTug » Mon Apr 09, 2018 4:39 pm

Quote: "Would it be possible to actuate the opening and closing of valves directly by using steam?"

To effect any sort of precise motion, a gas is a very poor medium in which to accomplish this, it normally involves closed loop systems with linear encoder feedback. Especially a gas that has to be kept above a relatively high temperature lest it implode on itself :).

Electromagnets (solenoid coils) use a lot of current which is a negative to shaft horsepower on a self contained plant.

-Ron
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Re: Steam Actuated Inlet Valves?

Post by DetroiTug » Mon Apr 09, 2018 4:50 pm

Quote: "My experience on a Fletcher Class destroyer with Worthington vertical pumps, that had free piston main valves, was often one of frustration. Not if, but when the main valve hung-up the only way to restore operation was to whack it with a 4lb hammer since there wasn't external means to move the valve."


I've never had that issue with the Southworth steam pump, not once ever has the shuttle piston stuck. It's a very close fit and Of course I do have an oiler on it.

-Ron
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Re: Steam Actuated Inlet Valves?

Post by marinesteam » Mon Apr 09, 2018 6:06 pm

Yes it would, they already exist. Google Steam piloted piston solenoid valve.

Not sure what you mean by very fast. The speed will usually be determined by the shuttle time of the solenoid and the pressure differential in the valve.

Ken

TriangleTom wrote:Would it be possible to actuate the opening and closing of valves directly by using steam?

Essentially, I'm thinking of a situation where a small amount of steam could be admitted to a small cylinder via a small solenoid. This steam would then force itself against the piston, which is attached to the main valvegear (presumably poppet), thereby opening the valve against the pressure of the steam and admitting steam into the much larger main engine cylinder.

It seems like this would be a good way to electronically control an engine while at the same time allowing very fast valve actuation, without the issues inherent in using much larger solenoids to control the admission directly. Presumably, because the advantages are mostly for the intake valve this would be best suited for a uniflow application.

I've done some research and so far I haven't been able to find any information about this having been tried in the past, although I'm sure I'm not the first person with this idea.
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Re: Steam Actuated Inlet Valves?

Post by DetroiTug » Mon Apr 09, 2018 8:25 pm

This subject comes up quite often in the experimental steam car community and electronic valves on a steam engine is often sought after but always abandoned. Run in to too many issues cycling a solenoid thousands of times per minute, even a few hundred is problematic.

-Ron
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