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T O P I C    R E V I E W
urquiola Posted - May 20 2010 : 11:26:20 AM
Hi!: as you all know, when Toyota presented the concept of air injection in exhaust port to improve Wankel performance, specially fuel economy, they added also a Reed Valve (RV) close to the trochoid surface in the peripheral intake port; peripheral intake with variable geometry intake manifold made Mazda win Le Mans endurance and fuel use race (-SAE Paper 920309 , Ritsuharu Shimizu et al.). Yanmar Diesel showed also that reed valves improved the partial load and low r.p.m. performance of their small charge-cooled rotaries (SAE Paper 720466 Kojiro Yamaoka & H. Tado), but I got a letter from David W. Garside, that developed the Norton series of Rotary engines, telling that reed valves do impair the high r.p.m. performance, an untoward fact for their engines. As street car engines don't work long times at high r.p.m., anything improving low rpm and partial load performance would be very good for the average driver. RVs do generate opening and closing extra-flows, like an hydraulic ram, that improve volumetric efficiency; also, by tilting the RV angle, you can induce any desired amount and direction of swirl inside the combustion chamber, thus regulating flame speed and engine emissions. I had the concept of installing an Husqvarna 500 cc 2-Stroke engine prismatic reed valve in a rotary with peripheral intake, to improve low speed torque, fuel economy and emissions. I send this note to see if there is anybody with the expertise and will to receive the torch of this concept, implement it and let us know the results. Regards, salud +
15   L A T E S T    R E P L I E S    (Newest First)
urquiola Posted - Jan 29 2015 : 1:38:53 PM
Hi!: some old papers show improved results with new materials, and different results with different fuels and lubricating oils.
Anybody commenting about the availability of seals made with different materials?
('Material' comes from the latin term for: 'Wood')

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urquiola Posted - Jan 24 2015 : 08:41:41 AM
Even when the research is almost 40 years old, and that the risk of a solid material petal from a Reed-Valve detaching and entering the working chamber always exists, perhaps a grid just before the port may prevent this, you may have a look at the documents below, pointing to good results with R-V, not only in the small line of charge-cooled rotor, air cooled housing engines of Yanmar Diesel, but in car size RCEs. You know that HC in exhaust are in inverse relation to Rotor surface temperatures, the hotter the Rotor working surface, the less the HC in exhaust, also a hotter Housing surface, from 80║ C to 130║ C reduces HC by 20%; a mineral oil charbonizes at 220║ C (Reference: Rotativementvotre) but a synthetic oil resists 50║ C above this, in kart engines such as Aixro, an intake transfert port abobe 130║ C means risk of severe damages, and an indication to release throttle or stop, this higher working temperatures could be approached by improved materials, also the article in SAE Journal, Feb 1978, points a much cleaner exhaust gas, and improved fuel economy with Iron housings instead of Aluminun. It also remarks that at 3'000 rpm, RCE friction HP losses are 55% of that required in a reciprocating engine; Toyota tested their RCE in Crown sedans, and had 9-11% better fuel economy than with their reciprocating engines. Thanks for your patient attention.

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urquiola Posted - Oct 01 2014 : 1:03:58 PM
A SAE paper by Husqvarna people, about to be available, entitled: 'Advanced low friction engine coating applied to a 70 cc high performance chainsaw', 2014-32-0115, promises a noticeable advance in materials applied to RCEs. Surface coatings must retain the oil film necessary for lubrication and friction reduction, must be cheap to apply, and compatible with seals' materials for low wear and a good engine life. Let's see how the whole thing evolves.
Image is from the 1997 SAE book by Takashi Suzuki, Ph.D. 'The romance of engines'

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urquiola Posted - Jun 13 2014 : 07:56:21 AM
Hello again!: besides documents cited, you may like looking in Espacenet for Ishikawa et al (Nissan), 1974 US patent 3844256; and R Yamauchi, 1970 US patent 3514235. Some charts on PP vs SP and Admission and Exhaust Pipe lenght effect are included in post; for more info: SAE paper 2013-32-9161, Dun-Zen Jeng et al, about: 'Intake and Exhaust Pipe effect on RCE Performance'. For small engines: SAE paper 2014-01-2160, by Wei Wu et al, about a 'Heat Pipe assisted Air-Cooled (UEL) Engine, for better Durability, Power and Efficiency'.
According to John Robinson, about 2-Stroke engine tuning, (Newnes Technical Book) square ports do give the best results, but are also the least kind to seals, perhaps this could be overcome by rounding/streamlining the duct-chamber intersection, from the usual rect angle, to something softer, from which the seal won't get a hammer style contact when crossing the port and meeting the port end.
Many times this type of minor changes are not implemented by the engine makers, because cost of having this in the production line would be too high, perhaps the industry standard for a novelty to be incorporated into series would be that a technology change should offer a 10% performance improvement along with a 10% cost reduction; the policies where workers got prices for discovering things as the way to use two screws for a task instead of three, saving some hundreds of thousands screws every year, seem no longer in force.

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urquiola Posted - May 15 2014 : 10:28:28 AM
Canadian Patent 1045553, by Ford, accessible for free download in Espacenet, is about a Reed-Valve controlled peripheral intake Wankel RCE, patents US 3848574 and 3991722, both by Kawasaki, are about a way to improve combustion, reducing emissions and improving fuel economy by opening a cone-shaped hole from the leading edge plug hole towards the trailing part of combustion chamber, and about a charge cooled RCE; the Yanmar Diesel SAE paper 720465 contains info about the results with a Reed-Valve in their 300 cc per chamber, air cooled housing Wankel RCEs. I guess the concept could be tested by making a Rectangular shaped Peripheral Port (SAE paper 780418, from NSU) in a 13B housing, controlling it for example with the system of Plenum ducts and Pyramid Reed-Valves from a Quad 2-Stroke engine.
These rather small PPorts could be used in addition to the existing Side Intake ports for having both the good idle and part load functioning of Side Ports, plus the much better power and MEP of Peripheral Ports. Would you like testing al least the Kawasaki plug hole change, and give us some info about your results? If you have some spare housings and need dissasembling an engine, testing the concept won't put your engine at risk. Thanks. Salut ć

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RussellAhmed Posted - Nov 24 2013 : 10:51:34 AM
Toyota is a tested and super brand you know........In Automotive Engineering section serve us greatly for its saving cost....In simply i may said "awesome"
RussellAhmed Posted - Nov 24 2013 : 10:38:03 AM

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urquiola Posted - Nov 20 2013 : 7:27:01 PM
SAE paper 720357 'Combustion Characteristics of Rotary Engines', by K Yamamoto et al., describes the important issues of combustion chamber recess shape, among it the S/V ratio and the quenching it induces, plug placement, and the steps taken for improving it, almost the same info is in SAE 'Automotive Engineering', July 1972, Vol 80, n║ 7, pp 26-29, at a reduced cost. The Toyota research about air injection on exhaust and use of glow-plug of SAE paper 790345 'Analysis of light-load performance in Rotary Engines', by T Kohno et al.,is in Automotive Engineering, August 1979, Vol 87, n║ 8; pp 33-38. Hope you enjoy it!
urquiola Posted - Nov 15 2013 : 09:22:04 AM
Ford not even tested, along with Toyota, the Reed-Valve control for Intake Ports in their Wankel RCEs, but has two patents about it, Espacenet publication numbers are:
CA1032477 and CA1045553
An article in SAE Journal, (Automotive Engineering) Vol 86, n║ 2, Feb 1978; pp 31-42, describes in detail the advances in REs worldwide, and another one in Automotive Engineering, Vol 87, n║ 8, August 1979; pp 33-38, summarizes the Toyota results (of SAE paper 790435) on ways to improve light load combustion of REs, basically air injection in exhaust port, and a glow-plug in the leading site plug hole.
Full SAE journal back issues available for download at sae.org at U$15 each. Enjoy it!
Aaron Cake Posted - Oct 14 2013 : 10:37:30 AM
A 13B with stock ports at 8000 RPM moves about 300 CFM when the inlet is at atmospheric pressure. Air pump, no idea but it is much, much less.
urquiola Posted - Oct 13 2013 : 11:11:47 AM
A question: is there somebody willing to provide us with data about the flow of air (liters/min) and pressure (psi, or another unit: lb.ft, kg/m2, kg/cm2, gr/cm2, and so on...) at which the air pump injects air in the thermal reactor or in the emission reduction systems in the RX-7 and other RCE Mazda cars' exhaust, and also the same in connection to the displacement and power of the Wankel Rotary engine?
Thanks. Best regards. Salut ć
urquiola Posted - Sep 07 2013 : 05:40:32 AM
There's some room for improving Volumetric Efficiency of RCEs at low rpm, as pointed in the Curtiss-Wright's figures from SAE paper S236, by R T Hurley, also published in SAE Journal, June 1960, and the K Yamamoto 1981 book'Rotary Engine'. Let's see what happens if proposed changes are implemented. Salut ć

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urquiola Posted - Aug 22 2013 : 08:19:03 AM
Thermal Efficiency of an Engine can be expressed by: 100(1-Te/Tp) -in %, Te= Exhaust Temperature, Tp=Peak Combustion Temperature; as pointed in the 'Wankel Engine Breakthrough' YouTube Video, Wankel RCEs have high Exhaust Gas Temperatures, that from the early days of Internal Combustion Engines are known being linked to low Effective Compression Ratio, these first times because of poor quality of available gasoline. If changing the plug hole to an slot as Ernie Brink proposes, reduces greatly the Exhaust Gas Temperatures, this would mean a much higher Effective Compression Ratio, improving the overall efficiency of Wankel Engine; this looks as a change worth testing, but some welding and trochoid surface coating expertise is needed. Rounding the plug hole-trochoid surface intersection corner, and also port-trochoid surface intersection would improve engine's life, as it would minimize chances of seals hitting hardly the hole borders. We wait for more experimental data about these modifications, please! Salut ć
Boquilla=nozzle, port, tube, duct, hole.

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Aaron Cake Posted - Jul 06 2013 : 10:34:06 AM
Mazda also has to follow very strict emissions guidlines, which is part of the reason the emissions system was always very complicated on the rotary. Unlike the pison engine the rotary emissions systems needed to deal with overlap, high EGTs and in general a far more "2 stroke" like exhaust output. They have always made judicious use of secondary air from the air pump, alternately injected into the exhaust ports, into the intake manifold, into the cat or vented depending on conditions. Or sometimes all 3. For example, during light decel air is directed into the intake manifold to lean the mixture and prevent backfires. During warmup it's pumped into the exhaust ports to combine with the rich mixture which lights off the cat.
urquiola Posted - Jun 29 2013 : 4:58:15 PM
Your comments are right. I just would like to remark that the people around the Corvair flat-six air cooled engines say that if you have the opportunity, it's better that you have the valve seats reinstalled and the whole think reviewed, as the engines that left the production line of GM were not very well finished, and it's better having the valve seats and other things in the engine having a remake by an expert. Mazda is a serious producer of engines and autos, but sometimes, the kind of changes that private owners can apply to their engines wouldn't be practical in a big output production line, this may be the reason why some changes described by private researchers or even other engine makers are no applied to the series.

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