New design ideas for model engines

[Nikhil Bhale]

Hi,

With the covid 19 situation still going on and I being stuck on an offshore oil field for last 6 months my mind is going all places.
These are a few things that I came across as a marine engineer. I sometimes dream of using these design ideas in a model engine of my own.
I don’t know if the below design ideas are already used in model engines or they are too difficult to implement here.

1. Hydraulic operated exhaust valves
Modern two stroke crosshead engines have a hydraulically operated air sprung exhaust valve. The cam operates a hydraulic pump instead of a push rod. Oil (from the engine LO system) displaced by the pump operates a piston in the exhaust valve which pushes the valve open. Instead of mechanical springs, the valve has an "air spring". Air at 7 bar is led via a non-return valve to the underside of a piston attached to the valve spindle. As the valve opens, the air underneath the piston is compressed. The expansion of this compressed air, when the hydraulic pressure is relieved assists in the closing of the valve. The air is supplied with a small amount of oil for lubrication purposes. Air is also led down the exhaust valve guide. This keeps the guide cool and lubricated, and prevents the exhaust gas leaking up the guide. Excess oil which collects at the bottom of the air spring cylinder is drained to a collecting tank.To prevent the possibility of an air lock, the hydraulic system has a small leak off at the top of the exhaust valve hydraulic cylinder. Oil is made up via a non-return valve. A relief valve is also fitted. A damping arrangement on top of the piston in the exhaust valve prevents hammering of the valve seating.

• Oil-Free Labyrinth Piston Compressor

The unique technology is applied between the piston and cylinder wall and between the piston rod gland and the piston rod. The labyrinth sealing effect is created by numerous tiny throttling points. At each of these throttling points, pressure energy is transformed into kinetic energy as a result of the flow restriction. The process continues at each throttling point/volume chamber combination along the piston and piston rod gland until the required reduction in pressure is attained. A small clearance volume is maintained between the adjoining surfaces. The low level amount of gas passing through the sealing system is recovered internally. SEPARATION OF SEALING AND GUIDING ELEMENTS – FOR LOWEST WEAR AND LOWEST MAINTENANCE The strict separation of the lubricated guiding elements in the crankgear from the contactless sealing elements of the piston and piston rod is essential for the functionality and efficiency of the compressor. The oil scraper rings, located close to the guide bearing, ensure the most efficient removal of oil from the piston rod. Lubricating oil is prevented from entering the compression room.
Actually the above are compressors but can the above design idea used for low pressure two and four stroke engines?

I dont see myself making anything this complicated just now. I will be happy if anyone of you can make something out of these designs.

Rgrds
Nikhil

 

[SmithDoor]

Looks great
That would great on the old horazonl hit and miss engine too.

Dave

1. Hydraulic operated exhaust valves
Modern two stroke crosshead engines have a hydraulically operated air sprung exhaust valve. The cam operates a hydraulic pump instead of a push rod. Oil (from the engine LO system) displaced by the pump operates a piston in the exhaust valve which pushes the valve open. Instead of mechanical springs, the valve has an "air spring". Air at 7 bar is led via a non-return valve to the underside of a piston attached to the valve spindle. View attachment 118185

• Oil-Free Labyrinth Piston Compressor

The unique technology is applied between the piston and cylinder wall and between the piston rod gland and the piston rod.
Rgrds
Nikhil