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Gallery, Projects and General => The Design Shop => Topic started by: radfordc on June 16, 2011, 11:32:52 AM

Title: Rotary valve 4 stroke engine.
Post by: radfordc on June 16, 2011, 11:32:52 AM

I'm in the process of developing a four stroke engine using a rotary valve in the head.  Here is the concept:
(http://i1038.photobucket.com/albums/a462/radfordc/Model%20Engines/rotaryvalve4stroke.jpg)

The carb will be mounted on the side of the head as was done on the Webra T4 engine:
(http://i1038.photobucket.com/albums/a462/radfordc/Model%20Engines/webrat4.jpg)

My concern is how the lower end of the engine gets lubricated.  If the fuel/oil mix is only circulating through the head and cylinder what happens to the rod and crankshaft?  On some models of the Webra the carb was actually mounted on the side of the crankcase and the mixture was inducted through the lower crankcase before going to the rotary valve head. 

(http://i1038.photobucket.com/albums/a462/radfordc/Model%20Engines/webrat41.jpg)

But, obviouly other models of the Webra don't do this.  I assume that they rely on fuel/oil blowing past the cylinder ring for lubrication?

Charlie

Title: Re: Rotary valve 4 stroke engine.
Post by: HS93 on June 16, 2011, 11:40:44 AM

Looks great, I wonder how you could water cool it for boats ? I have been looking recently at some of the 4 stroke engines on the market to see if they could be water cooled up to now no luck os did one some years ago but because they did not make many they are not cheap.

peter

Title: Re: Rotary valve 4 stroke engine.
Post by: radfordc on June 16, 2011, 12:23:01 PM

If this engine works it would be relatively simple to drill the head for water passages and make a water jacket for the cylinder. 

Title: Re: Rotary valve 4 stroke engine.
Post by: nearnexus on August 12, 2011, 06:46:46 PM

I can't see how you would get sufficient blow-by to lubricate the mains and bottom end bearings, even if they are roller or ball type.

Through the crank case carburation looks the way to go.

Maybe the engines without this rely on sealed bearings ?  Have you checked on this?

How are you sealing the ends of the rotary valve shaft ?

Title: Re: Rotary valve 4 stroke engine.
Post by: BarryG41 on August 14, 2011, 01:12:45 AM

Thing is that oil -fuel mixture  crankcase carburettor is 2 stroke motors.  How long do you intend for it to run? if it is longer than 5 minutes  then the easiest is a simple oil pump running off  the crank with a total loss sump. i.e. the oil just  drips out on the ground.  Popular with speedway motocylce  racing engines.  This requires an external oil container and if you don't like the total loss system add a secong oil pump to scavange the oils out of the sump it back to the oil tank.  Now you have a  dry sump system.
Barry

Title: Re: Rotary valve 4 stroke engine.
Post by: loply on August 14, 2011, 07:21:40 AM

Can you not just fill it with oil, like any other 4 stroke engine, and rely on splash lubrication to lubricate the bottom end?

Title: Re: Rotary valve 4 stroke engine.
Post by: nearnexus on August 14, 2011, 06:30:31 PM

Oil/petrol mixture can be used to lubricate a four stroke engine.

It's use has nothing to do with the engine cycle.

It's just another way of oiling things.  The only determining factor is that the mixture passes all the rubbing/wearing parts and is sufficient quantity.

The only really high wear area in a four stroke is the camshaft and In this case there is no camshaft.

Title: Re: Rotary valve 4 stroke engine.
Post by: BarryG41 on August 15, 2011, 01:58:35 AM

Petrol oil mixture in a 4 stroke is not unusual in fact very common with LPG engines.  Not seem crankcase mounted carburettor on any motor other than a 2 stroke
 

Title: Re: Rotary valve 4 stroke engine.
Post by: radfordc on August 17, 2011, 04:47:51 PM

Quote from: nearnexus on August 12, 2011, 06:46:46 PM

How are you sealing the ends of the rotary valve shaft ?

I'm not.  I lapped the rotary valve to fit the bore in the head.  I'm hoping this will suffice?

(http://i1038.photobucket.com/albums/a462/radfordc/Model%20Engines/DSCF0008.jpg)

Title: Re: Rotary valve 4 stroke engine.
Post by: flutedchamber on September 18, 2011, 01:24:33 PM

I would think a seal would be needed, especially on the intake valve or it would suck outside air in and lean the mixture.  What about using a sealed ball bearing assembly on the end of each cam?  That would seal AND take care of any wear.

Title: Re: Rotary valve 4 stroke engine.
Post by: GypsyTinker on November 12, 2011, 07:42:12 PM

I was working on this idea a long time ago.

Check out the Coates engine/head

http://www.coatesengine.com/csrv-system.html

http://www.google.com/#hl=en&sugexp=ppwl&cp=9&gs_id=1e&xhr=t&q=coates+engine&pf=p&sclient=psy-ab&site=&source=hp&pbx=1&oq=coates+en&aq=0&aqi=g4&aql=&gs_sm=&gs_upl=&bav=on.2,or.r_gc.r_pw.,cf.osb&fp=5ee03872464f82ab&biw=1219&bih=685

Title: Re: Rotary valve 4 stroke engine.
Post by: John Hill on November 13, 2011, 02:55:02 PM

Quote from: GypsyTinker on November 12, 2011, 07:42:12 PM

I was working on this idea a long time ago.

Thats nice, but there is nothing new in the idea as rotary valve internal combustion engines date back to at least 1909..
http://www.aqpl43.dsl.pipex.com/MUSEUM/POWER/unusualICeng/RotaryValveIC/RotaryValveIC.htm#fray (http://www.aqpl43.dsl.pipex.com/MUSEUM/POWER/unusualICeng/RotaryValveIC/RotaryValveIC.htm#fray)

Title: Re: Rotary valve 4 stroke engine.
Post by: Brass_Machine on November 13, 2011, 11:38:43 PM

I have followed discussions on rotary valves. Some interesting stuff... I will be watching this.

Title: Re: Rotary valve 4 stroke engine.
Post by: GypsyTinker on November 14, 2011, 09:05:20 PM

yeah... I wasn't claiming to be the first.

The sealing is the key and coates got it right. I learned that from when I was working on this a long time ago...