A question about the ignition

[toystoretom]

I am a bit confused but here goes anyway.

The rotary engine spins and actually fires three times during one complete revolution of the rotor meaning that the spark plug has to fire 3 times.

I am looking at the points cam and it looks like it only has one lobe? How is this firing the spark plug three times?

Another question: If the engine is running at 6000 RPMs and the spark plug fires 3 times per revolution does that mean the points are opening and closing 18,000 times per minute? How in the heck can mechanical points keep up with that? They have to be on the verge of floating.

I must be missing something ;D

Tomo

[goandy]

The crank turns three times for each full rotation of the rotor, so one spark per crank revolution.

[wayne]

Also, I think that only the B point cam is single lobe. The A point cam (the inner cam) is dual lobed and with the gearing that works out to one spark per 1/3 rotation of the rotor which is equivalent to 1 spark for 1 full rotation of the crankshaft.

[toystoretom]

Ah Ha... this makes more sense. The crank spins 3 times faster than the rotor.

Which brings up another question: When the tach reads 6000 RPMs does that mean the crank is spinning at 6000 RPMs and the rotor at 2000 RPMs...

or..

The rotor is spinning at 6000 RPMs and the crank at 18000 RPMs?

(Probably the first.)

If that were true, then at 6000 RPMs the points are opening and closing 6000 times while the rotor is spinning at 2000 RPMs.

Those points could handle that, and the rotor should last forever only spinning 2000 RPMs.

Tomo

[bdalameda]

Yes the tachometer RPM indicates the crankshaft (excentric shaft on a rotary)RPM. The rotor itself is turning 1/3 the speed. With the low 6500 rpm redline on the RE5, this really helps prolong the engine life because the tip speed of the rotor is in an operating range where the seals can survive a decent amount of time.