Vance claims the rotary is somehow more than 80 cubic inches,
He sites the three rotor faces as proof. Vance also claims
the fact that a single rotor engine fires once per output
shaft revolution is somehow irrelevant. I beg to differ.
Lets start with internal combustion engine basics. Work is
done when a given amount of air is mixed with the proper
amount of fuel and is allowed to burn in a closed chamber.
This greatly increases the pressure in that camber. If the chamber is
allowed to expand while imparting circular motion to shaft
work is done.
HP is work done in a given time period. More work
in one second higher the HP. Same work in a shorter period
of time higher the HP. Higher RPM is another way of saying
a shorter time period. A given amount of work is done
for each revolution of the output shaft. Therefor
more HP at higher RPM's.
Now it comes down to how much air can the engine pump in
one revolution of the output shaft. The Wankel one rotor engine
has three faces on the rotor. In one part of the wankel
the rotor face starts close to the housing and moves
away from the housing to a max volume or displacement of
40 cubic inches (.65L). See the illustration below.
Lets start at a shaft angle of 180 degrees and note that
chamber C is at a minimum volume. 180 degrees later
the volume is a max and all 40 cubic inches of air
has been ingested. Wow we have used up 180 degrees of
our allotted 360 degrees of our cycle and we are no
where near firing the mixture in that chamber. What is going on?
The answer is the rotor is a magic piston. It has three chambers
in different stages in the process that automatically
appear at the sparks plugs once each 360 degrees of
output shaft revolution. At angle 180 chamber A is
getting ready to fire. At angle 360 chamber A is expanding.
At angle 180 chamber B is starting to exhaust. At 360
chamber B has almost completed its exhaust phase
and so on and so on.
Each chamber changes its mode of operation according to
the position of the output shaft much like a piston engine.
A 4 cycle piston engine takes 180 degrees
of the output shaft for the chamber to change its mode
of operation from intake to compression to expansion and to exhaust.
One firing cycle every two revolutions of the output
shaft. It therefore takes two pistons to equal one rotor
and one complete firing cycle per output shaft revolution.
Same as the wankel.
The rotor takes 180 degrees of the output shaft to change
its mode of operation from; intake to compression to expansion
and to exhaust. Therefore the rotor needs 3 chambers working
simultaneous to equal two pistons in chambers that are
40 cubic inches each. Both engines pump the same amount
of air in the same time period and generate the same amount
of horse power.
To prove this the rotary can tell when to fire the spark plugs
by looking only at the output shaft position. On the other hand
the four cycle 2 cyl. piston engine must determine which of two possible
revolutions to fire the spark on. It does this by looking at
the cam shaft which rotates half as fast as the output shaft.
This is not to say there are three sets of spark plugs to fire
each rotary chamber three times as often. There are only one set of
spark plugs and each rotary chamber presents itself to these
spark plugs when it is ready to be fired. First one chamber
is ready and 360 degrees later the next chamber is ready
and so fourth and so on. How this is achieved in the
wankel is the subtle and the interesting part. The rotor
rotates only once in 1080 degrees of output shaft or
one third of output shaft speed. This is interesting
but irrelevant to the work done in any give time period.
The amount of horse power generated in other words.
I hope this is clear to everyone. Are there any questions?
Paul Lamar
Paul
That is a good article. Well written, and detailed.
Anyone should be able to understand it.
Glad you did it.
Royce
Thanks Royce. I need to update the one on this subject on the ACRE NL web site.
Paul Lamar
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