6 replies to this topic

[Moon Tricky]

Idea: a wedge-shaped piston ring that sits almost flush with the edge of the piston head, to minimise crevice volume:

Arrows show the direction of the pressure forces. The tapered inner edge of the ring against a tapered piston head forces the ring outwards as it is pushed down to form a seal with the cylinder walls. A lip at the bottom of the ring prevents the ring coming off.

Would it work? I don't know.
Or are there any other alternative piston ring designs?

[malbear]

Moon Tricky,
In my oppinion you are likely to have siezure or scuffing problems especially on the compression stroke as the piston is mooving upwards the wedging action could jam the piston to the cylinder wall.
It is simmilar to the Dykes ring only it has parrallel sides and no wedging . It relys on gas pressure to push the ring outwards and form the seal

[McGuire]

Crevice volume is a big deal in current production engines due to emissions concerns. Tightening up the skirt-to-wall clearance is key.

[cheapracer]

Originally posted by malbear
the wedging action could jam the piston to the cylinder wall.
It is simmilar to the Dykes ring only it has parrallel sides and no wedging . It relys on gas pressure to push the ring outwards and form the seal

Its a jammer for sure the moment the piston rocks, at the least very short life.

All common type rings rely on gas pressure to 'push' them both down and out, the Dykes was a better answer in another time.

[Moon Tricky]

Originally posted by cheapracer


Its a jammer for sure the moment the piston rocks, at the least very short life.

All common type rings rely on gas pressure to 'push' them both down and out, the Dykes was a better answer in another time.

The gas pressure does push it down and out, it just does it diagonally instead of one way and then the other. Although on the upstroke, it's true, also the cylinder wall is also going to pull it down, so I get what you mean about jamming... hang on, I've got another idea...

[Feliks]

Originally posted by Moon Tricky
Idea: a wedge-shaped piston ring that sits almost flush with the edge of the piston head, to minimise crevice volume:

Arrows show the direction of the pressure forces. The tapered inner edge of the ring against a tapered piston head forces the ring outwards as it is pushed down to form a seal with the cylinder walls. A lip at the bottom of the ring prevents the ring coming off.

Would it work? I don't know.
Or are there any other alternative piston ring designs?

Happens what in intake stroke ?? Forces the ring outwards as it is pushed up??

Regards Andrew

[J. Edlund]

I would think that the primary concerns by using such a design would be in cooling and the weight of the ring. The ring is very exposed to the combustion, and it also sits very high on the piston where temperatures are high. It could also be difficult to get the ring reasonably light, so that inertia forces doesn't have a negative effect on sealing.