starapex

The Wankel rotary engine configuration was first patented by Bernard Maillard in 1943 as a compressor.

When Mazda first inspected the engine at NSU it required 2000 rpm to start it. It would run rough at low speed but a coin could be balanced in it then it was turning at high speed.

The rotary engine today only produces about 85 psi pressure turning at 250 rpm.

85 psi is not sufficient pressure for proper ignition to start an engine rotary or piston. The starting problem was solved by the installation of two spark plugs for each rotor.

The first sparkplug poorly ignites the fuel blowing it into the advance area of the rotor and at the same time increasing the internal pressure to over 120 psi. The 2nd sparkplug fires a moment later in this environment to create a functional power stroke.


All the manufacturers had snatching problems when the engine was cruising These problems would increase to jerking and bucking as the engine aged.


The problem is inherent in an engine with the exhaust port in a position that has the apex seal slide over the hole when a leading surface is in the compression stroke. The power stroke pushes against the rotor and holds the gears against the leading edge of the stationary gear. When the apex seal slides over the exhaust port the pressure is released and the compression pressure pushes the rotor back and against the trailing edges of the stationary gear.

Mazda moved the exhaust port to open earlier to a position so the exhaust is released before the compression stroke has started.

In this instant one third of the displacement has not yet taken place and the eccentric shaft lobe has just reached the 3 o'clock position in relation to the rotor surface.

There is room for improvement



THE WORKING CYCLES OF THE PERFECTED WANKEL ROTARY ENGINE

For proper functioning the intake port must be peripheral and located between the 6 :30 to the 7:30 o’clock housing position. The exhaust port must be peripheral and located just at or past the 6 o’clock housing position.

With the sparkplug surface of the housing facing up.
The starting point has eccentric shaft lobe (crank shaft throw) at the 12 o’clock position
The A surface of the rotor is facing up with its trailing apex seal in the 10 o’clock and the leading apex seal at the 2 o’clock position.
The C surface of the rotor is facing the 4 o’clock position with its trailing apex seal in the 2 o’clock and the leading apex seal at the 6 o’clock position.
The B surface of the rotor is facing the 8 o’clock position with its trailing apex seal at the 6 o’clock and the leading apex seal at the 10 o’clock position.

(1)When the eccentric shaft lobe rotates from the 12 o’clock to the 3 o’clock position the A surface completes its first third of its power stroke. The rotor apexes move to the 11, 3 and 7 o’clock position
At the same time the C surface completes its 2nd third of the exhaust stroke.
At the same time the B surface completes its last third of the intake stroke.

(2) When the eccentric shaft lobe rotates from the 3 o’clock to the 6 o’clock position the A surface completes its 2nd third of its power stroke. The rotor apexes move to the 12, 4 and 8 o’clock position
At the same time the C surface completes its last third of the exhaust stroke.
At the same time the B surface completes its first third of the compression stroke.

(3) When the eccentric shaft lobe rotates from the 6 o’clock to the 9 o’clock position the A surface completes its last third of its power stroke. The rotor apexes move to the 1, 5 and 9 o’clock position
At the same time the C surface completes its first third of the intake stroke.
At the same time the B surface completes its 2nd third of the compression stroke.

(4) When the eccentric shaft lobe rotates from the 9 o’clock to the 12 o’clock position the A surface completes its first third of its exhaust stroke. (The location of the port makes this stroke a continuation of the power stroke with the compression of the exhaust assisting the compression stroke. The rotor apexes move to the 2, 6 and 10 o’clock position
At the same time the C surface completes its 2nd third of the intake stroke.
At the same time the B surface completes its last third of the compression stroke.
The B surface will go through the same cycles mentioned before until the C surface completes its last third of the compression stroke. Then the C surface will go through the same cycles until the A surface completes it’s last third of the compression stroke and the circle of events is then repeated.

Cheers
Ken McKenzie

rxAustin

BS

BS

BS - they start fine on 1 plug per rotor.

BS

etc...

Where do you kids come up with this stuff?

gambone

iTrader: (3)

I all so say B S where did youever come up with your facts
# 1 I'm a tuner and do comperssion checks
# 2 My own 76 rx4 has 130 psi
# It will start and run on ether trailing or leading plug and is drive able.
GET FFFF EN REAL WITH WHAT YOU KNOW

Rotortuner

Ya, where did you get your info, cus hardly any of its true.

CJG

Barwick

I believe the 85 psi at 250 RPM.

Do a compression check with a Mazda compression tester.. at 750 RPM or so you get about 7 or 8 bar. I'd believe a cold rotary freshly rebuilt & broken in would turn 85 psi at 250 RPM.

gambone

iTrader: (3)

No been there and done it, freshly rebuilt and broken in at cranking speed 130 psi
Steve Gambone X Mazda dealer tech and still building motors. got my own mazda tester

rxAustin

Whether it makes 85 psi at cranking speed or not, it's enough to start the engine without dual plugs. A piston engine will also start with less than that.

starapex

Thanks for the information, I actually got 120 psi turning my first wankel prototype conversion from a RX-7 engine. Many years ago I rebuilt a 1955 pontiac and put 1950 pontiac rings in it. it gave only 85 Lbs Compression and it wouldn't start without pushing it with another vehicle. And then it was hidden in a cloud of blue smoke when I parked it.

I actually got the information from a Haynes manual For 1986 to 1991? the RX-7 They said to remove the stopper and the needle will bounce to 85 Lbs for each surface. They also say the engine is ok with up to 20 Lbs less.

SUPPOSED BS

((The problem is inherent in an engine with the exhaust port in a position that has the apex seal slide over the hole when a leading surface is in the compression stroke. The power stroke pushes against the rotor and holds the gears against the leading edge of the stationary gear. When the apex seal slides over the exhaust port the pressure is released and the compression pressure pushes the rotor back and against the trailing edges of the stationary gear.))

THIS DOES NOT APPLY TO THE MAZDA MAZDA SOLVED THE PROBLEM.

Mazda moved the exhaust port to open earlier to a position so the exhaust is released before the compression stroke has started.

I BELIEVE THIS TO SOLUTION MAKES A SMOOTHER RUNNING ENGINE WITH A LOSS IN EFFICIENCY AND POWER.

Cheers
Ken McKenzie

QuagmireMan

what schools did you go to, just out of curiousity.

madsci

The bucking and snatching was more of a peripheral intake problem - not so much the exhaust. Moving to side intake ports solved the problem. (There are other ways to go about solving this one)

starapex

Then why is the exhaust port so early that one third of the power stroke displacement is not used ?

88IntegraLS

But seriously, the rotary engine's only real design deficiency is its low thermal efficiency.

rxAustin

It's called "blowdown". Any engine - piston or rotary - opens the exhaust early. The reduction in thermal efficiency here is more than offset by the reduction in pumping loss on the exhaust stroke. High RPM piston engines have been known to open the exhaust valve halfway through the power stroke. Most of the power from combustion occurs over a narrow segment of the power stroke.

The real design deficiencies stem from combustion chamber shape:
1- high surface area to volume ratio. Lots of heat gets lost to the cooling system and is not available for making power. This is partially offset by not having to power a valve train.
2- quench zones, where combustion doesn't occur. See the R26B papaer for info on the "far trailing" spark plug that was added to race engines to help out here.

Barwick

Look on the back of your compression tester, I watched it on my last car, cranking around 700 RPM pulled 7 or 8 bar.

starapex

(It's called "blowdown". Any engine - piston or rotary - opens the exhaust early. The reduction in thermal efficiency here is more than offset by the reduction in pumping loss on the exhaust stroke. )

My personal observation of a first generation rotary housing shows a highly polished housing surface between the trailing plug hole and the minor axis.

This I believe is caused by the apex seal under extreme pressure from the power stroke just prior to the exhaust port opening.

When the exhaust port is reached by the leading apex seal the eccentric shaft lobe has just come to the three o'clock position in relation to the power stroke working surface. At this time one third of the displacement has not been used.

The piston engine creates most of the torque when the crankshaft throw is in the two o'clock to four o'clock position so the exhaust valve should start to open at the four o'clock position.

This does not apply to the Wankel rotary engine holding the pressure will create more totque and it will
also assist in pushing the rotor surface that is in the compression stroke. It will also transfer the heat to the opposite side of the housing for more uniform expansion

I am out of town til monday evening.

Cheers

Ken McKenzie

rotary emotions

Felix Wankel designed his first Wankel engine in 1923, at the age of 21. He knew the sealing problems couldn't be solved back then, so he first spend about 30 years working on sollutions to seal difficult shapes (anything not circular), after which the Wankel engine was patented in the early fifties.
If Maillard had patented his engine in 1943 it couldn't have been possible that Wankel patented his one later, could it?
The compressor/pump types you talk about are much older (18th century) and also very different.
The Wankel rotary engine was designed by Felix Wankel as DKM (drehkolbenmotor) and altered to KKM (kreiskolbenmotor) by his assistend. Felix Wankel first didn't like this, as the "new" engine was way slower, and showed up new problems (apex seals etc)
But it was at least useable for automotive purposes.
Maybe you need to read some books about Felix Wankel, so you don't write BS like this anymore.

KevinK2

Both engines are the same in that, on the power stroke, no torque is produced at the TDC and BDC positions, and little torque is produced near it, even if the chamber/cylinder is pressurized. you need a moment arm to create torque to the e-shaft.

karism

Oh my!

Ok...maybe go back to reading more before posting!

"The starting problem was solved by the installation of two spark plugs for each rotor. "

So why does mine start on the leading plug only? Not even to mention that it starts fine on the trailing plugs as well

(`82 12A J-Bridge Port ) Not only does it start..it drives as well!

Sir.Please refrain from posting if you dont know what your talking about.

Karis

Jeff20B

iTrader: (13)

I've actually forgotten to turn trailing back on before. It fires up normally and only the tach alerts me (since it doesn't read RPM until I flick a switch to turn on the trailing coil and ignitor). Some people need attention, and the internet is one way to get it.

Jeff20B

iTrader: (13)

2600 from uh tah ree.

starapex

“Felix Wankel designed his first Wankel engine in 1923, at the age of 21”

Wankel patented a concentric engine in 1934

“He knew the sealing problems couldn't be solved back then, so he first spend about 30 years working on solutions to seal difficult shapes (anything not circular), after which the Wankel engine was patented in the early fifties.”

If Maillard had patented his engine in 1943 it couldn't have been possible that Wankel patented his one later, could it?

It should not have happened the USA patent office wrongly issued it.

The art belonged in the public domain in 1960.

Page 54 Wankel by Nicholas Faith Published by Seen and Day New York.

Bernard Maillard in 1943 had patented the same configuration the triangular rotor in a peanut shaped housing. He voluntarily gave up in advance any claims he might have had to share in future patent rights’

Thanks to Maillard’s attitude models of the engine were shown to the Patent office in Munich in January of 1955 and the patents were granted.

“The compressor/pump types you talk about are much older (18th century) and also very different.
The Wankel rotary engine was designed by Felix Wankel as DKM (drehkolbenmotor) and altered to KKM (kreiskolbenmotor) by his assistend. Felix Wankel first didn't like this, as the "new" engine was way slower, and showed up new problems (apex seals etc)
But it was at least useable for automotive purposes.”

The KKM designed by Walter Froede of NSU and it is the identical configuration that was patented by Bernard Maillard.

“Maybe you need to read some books about Felix Wankel, so you don't write BS like this anymore.

Thank you Dr Felix Wankel! “

Cheers
Ken McKenzie

madsci

Regardless of who first used it as a compressor, the fact is that it makes a great one.

"In 1954, several test units of various sizes were built, and proved remarkably effective. One test compressor delivered air to the engine at pressures up to 8 atm (120 psi), with an overall adiabatic efficiency exceeding 70%."
(The Wankel Engine - Design, Development, Applications by Jan P. Norbye page 87)

So why isn't anyone making Wankel superchargers?

starapex

From Nicholus Faith's book WANKEL
The method worked splendidly as a compressor because of its mechanical efficiency. Indeed, in the summer of 1954, NSU took one of its rediculosly small fifty- cubic centimeter Quickly engines, souped it up by using a Wankel compressor housed in a mysterious black box, the contentsof which were never revealed to the public, and set a speed record of nearly 120 miles per hour on the Bonneville salt flats Utah, USA a record that still stands. (Book published 1975)

Confirmed again in Hohn B. Hege's book THE WANKEL ROTARY ENGINE published 2002.

It also says NSU also used Wankels compressor on a 500 cc motorcycle engine and produced 110 horsepower

The fact is the configuration is a superior supercharger and pump.

We only get innovation that it is within established guidelines.

Wankel designed his sealing grid for rotating valves during the second world war. therefore they should have been in the public domain in the early to mid 1960's

Bernard Maillard patented the Maillard compressor in i943 so the geometry should have been in the public donain in 1960.

The US patents issued in 1961 were kept valid to keep the inovation within established guidelines.

Cheers
Ken McKenzie
www.starapex.com

rotary emotions

Actually, after the Wankel rotary engine had been developed, Wankel started experimenting with compressors and other engine types again. He managed to build the worlds most efficient compressor, and sold the oncept to KKK (the turbo-builders). He also build extremely powerfull engines.
I'm still not really understanding what's being writen about Maillard here. As far as I can understand, he designed more or less the same engine, not knowing of Wankels achievments? That still doesn't change the fact that Felix Wankel was first, does it? Or do I read that incorrect? (could be, I'm not a native English speaker, so I can make mistakes )
Anyway, I'd suppose we can agree that it were Wankel and Froede who are indeed the fathers of the current Rotary engine design?

rotary emotions

check this: (I believe it can be translated by babelfish or something):
http://www.der-wankelmotor.de/Felix_...ix_wankel.html
The latest compressor type is at the bottom.