Crash

I'll preface this post by saying that I am not an engineer (and may not be calling things what they should be called) but, very interested in the rotary and understanding how it works.

Ok so I have been thinking about how a rotary works and it occurs to me that there may be power in changing the shape of the rotary. Given this is total armchair engineering but lets think about this:

What if there was more volume at the leading point of the rotor for the combustion to go as it spins around?

Think about a rotor with a shape like 3 semi-circles arranged to create the 3 points of the rotor. Or, in more artistic terms, the edges of the rotor creating somewhat of a ? shape or teardrop shape. In theory this could direct combustion toward the leading edge of the point of the rotor, creating more force to propel it around.

My only thought is that this could possibly lead to more volume during the compression phase of the cycle, meaning the fuel/air mixture might not compress enough to create sufficient combustion.

I'm sure this idea has been thrown around in 30+ years of rotary development but, can someone confirm my suspicions about the downfalls of such a design?

Thanks in advance!

strokercharged95gt

im sure for one reason or another the design is the best way it could possibly be. Engineers have been working with rotaries far too long not to think of something better than the current design. Im sure they can manipulate the charge in the combustion chambers effectively by using the 2 spark plugs in a precision sequence. mazda needs to make some lower compression rotors and give a turbo from the factory.

bgreene

there is a rectangular cavity in the middle of each face of the rotor to create some room for combustion, and this does reduce compression some from the maximum theoretical ratio that could be achieved with a smooth face, but there are trades in any sort of design.

The main downside to putting a "full width" pocket near the leading edge of a face that I could see would be the possibility for more exhaust gas to get carried through into the next cycle since it could create a region which has an extremely short exposure to the exhaust port. Extending the port to reduce that effect could lead to more overlap of the intake and exhaust strokes, which was a big part of why the rotary engine was off the market for several years (port overlap generally reduces fuel efficiency, makes emmisions horrendous, and can hurt performance which opposes the whole reason for reshaping the rotor).

Until we get the technology for a self-deforming rotor, which could move its center of pressure along the face for different strokes in the cycle, we're stuck with trade-offs to optimize performance across all four strokes as a whole. There should be benefits in torque and power to be had by moving the CP "forward" on the face during the combustion stroke, forward CP location could be detrimental in other strokes, and the apex seals probably couldn't be modified to allow for much variation of the housing shape to customize chamber shapes for each stroke of the cycle.

ZOOOMO

I believe that the limit is always the strengh of the metal.
Imagine having rotors with spoonlike side characteristics instead of a pocket in the middle to allow for combustion.
The tips would need to be from magical material.
I believe it will be a matter of fact in the future, as soon as material science catches up.
A thing of beauty like a rotary engine will come to age sometime...
IMHO

Razz1

http://www.quasiturbine.com/

Gerael

whats the point of bringing up quasiturbine... its a nice theory.. needs a lot more development..


but anyway.. i just thought of an idea for a variable rotor displacement system...mazda if you're reading this.. i'm looking for a job.. hah

anyway... where the rectangular cavity is, you replace that with a sort of piston block that can either move outwards towards the rotor housing or towards the eccentric shaft. The eccentric shaft then has the center portion of a lobe cut differently so that it would act as a sort of cam that pushes out on the piston block...

if timed correctly (and i checked by watching rotary motion moving around and around) the piston block would be out towards the rotor housing during the compression and end of exhaust cycles which would act to have higher compression ratios and push out more exhaust gas... during intake the cavity opens up and draws in air.. and combustion it also enlarges the chamber to how our normal rotary has it...

I'm not sure of the possibilities of having this sort of cam on the eccentric shaft... but its a way to have variable displacement rotors..