RKM engine

RKM engine

The Rotary Piston Machine, or in its German originalRotationskolbenmaschine (R.K.M.) is a new (still in development) formof machine. It can be used either to transform pressure intorotational motion (an engine), or the converse - rotationalmotion into pressure (pump). It is still indevelopment, but has possible applications in fields requiring oil,fuel or water pumps, as well as pumps for non-abrasive fluids whenmiddle or high pressure is required. For instance: Hydraulics, fluidand gas transport systems, presses, fuel injection, irrigation,heating systems,hydraulic lifts, water jet engines, hydro- andpneumatic engines, and medical pumps.Schapiro, B., "The RKM Rotary Piston Maschines" In: Vernetzte Wissenschaften, Eds: Peter Jörg Plath und Ernst-Christoph Haß, Logos Verlag, Berlin 2008 ] The machine's inventor is Boris I. Schapiro, along with with co-inventors Lev B. Levitin and Naum Kruk.


All versions of the RKM incorporate a working chamber formed bysmoothly conjugated circular arcs. The piston, shaped to conform tothe chamber's walls, "jumps" from wall to wall, thus performing arotary motion. The piston has an appropriately shaped aperture fittedwith a gear structure, and this drives the power shaft (or two powershafts in some models).

The piston, its aperture and the working chamber of the RKMsrepresent, in their cross sections, multi-oval figures which,mathematically, are related to the class of figures of equal width. Those multi-ovals are non-analytical figures with adiscontinuous second derivative of the contour line (thecurvature). Hence, generally speaking, the trajectories of theircenters of curvature are also non-analytical and, within the RKMs'geometry, have to have singular points.

In relation to the piston, the trajectory of the power shaft axis hascorner points, which correspond to extreme positions of the piston asrelated to the working chamber. Those corners, which representsingular points of the power shaft's trajectory, cannot be avoided orrounded to provide for the kinematically closed functioning of thegear.

The reason why until now the geometry of figures of equal widthcould not be put to practical use in the gear design is that noconventional gear structure with the regular rolling on of the gearswould permit the exact rolling-on of the singularities. The RKMs solvethis problem by introducing the "inversely conjugated gear system",which makes it possible to have singular trajectories of the axes ofrolling-on gears and, thus, allows the transfer of the angularmomentum during the passage of the piston through its stoppositions. [http://www.rkm-schapiro.org/comm.php RKM's - Rotating Piston Machines - Scientific and Technical Comments ] ]

In simple words, the gear mechanism introduces corrections to thepiston's motion, correcting the axis of rotation as it leaves thestop positions, so as to create a smooth motion.

Possible Configurations

In theory, there is no limit to the number of "sides" that a workingchamber may have. However, in practice, it is likely thatconfigurations incorporating no more than seven arcs will be used.

In addition, there can be either one or two power shafts in theaperture in the center of the piston.

Of course, the exact configuration of every model depends upon itsuse. For instance, internal combustion engines would include injectionvalves and after-burning chambers. These, however, are not part of theRKM concept.


Potential areas of application for the RKM engines include: [http://www.rkm-schapiro.org/exesum.php#03 RKM's - Rotating Piston Machines - Project Summary ] ]
*Pumps: medium-, high-pressure, and pre-vacuum pumps for use in power machinery, refrigerators, elevators, lifts, cranes, road-building machinery, automobiles, aircraft, and other applications, including those for domestic water and heating systems,and scientific research.
*Compressors: medium- and high-pressure compressors for a wide range of industrial and consumer applications.
*"Cold" motors: hydraulic and pneumatic motors for use in automobiles, air-, space- and marine craft, and in a number of other applications in industrial and consumer products.
*Power tools: a new class of power tools for drilling, cutting and surface treatment of materials in various ranges (from super-large to micrometre).
*Internal and external combustion engines, including Diesel, for all types of wheeled or tracked motor vehicles (from motorbikes to automobiles and trucks, to Mars explorers), marine craft of all sizes (from pleasure boats to supertankers), helicopters and propeller-driven aircraft (including super-light platforms).
*Electric power generators for agriculture and industry, including oil and gas production, air & space industry, large stationary and vehicular power generators, compact emergency generators, etc.
*Compact sources of electrical power for portable computers and other electronic devices, etc.

One area where RKMs offer very high potential is in the pump market. RKM pumpscan be as, or more, efficient as today's preferred pump technologies, whileoffering overall advantages in pricing, size, reliability and energyefficiency Schapiro, B. and Terlitsky, L., "The RKM (RKM) Rotary PistonMachines with the Jumping Momentously Axis", Proceedings of the InternationalConference on Sustainable Automotive Technologies 2008 (ICSAT2008), 4th to 9thNovember 2008 in Melbourne, Australia ] .

Comparison To the Wankel Engine

Despite their apparent geometrical similarity, the RKM and the
Wankel Engine are quite different in design. The main similaritiesbetween them are the shape of the working chamber and the use ofrotary motion.

However, there are many differences between the two. The WankelEngine working chamber is mobile while the RKM chamber isstationary. The axis of rotation in the Wankel Engine moves in acircle while that of the RKM is fixed (in the single power shaftversion, temporarily with two possible positions). In the RKM motor, theignition takes place in a compact recess, while the Wankel's is in the workchamber itself. The RKM's sealing elements are in surface contact with the workchamber and pistons, as opposed to the Wankel's line contact. This makes for anumber of advantages of the RKM motor over the Wankel:
#Easier adaptation to diesel fuel.
#Support of forced afterburning of gases, which is not feasible with the wankel geometry.
#Longer life, lower fuel consumption and higher efficiency.

One application that the two may indeed have in common isminiaturization. A miniature Wankel Engine has been successfullyconstructed [Fu, K., Knobloch, A., Cooley, B., Walther, D.,Fernandez-Pello, A. C., Liepmann, D., and Miyasaka, K., MicroscaleCombustion Research for Applications to MEMS Rotary IC Engine,Proc. 2001 National Heat Transfer Conference, Anaheim, CA, June 10-12,2001.] , and it stands to reason that the same can be done for anRKM.

See also

* Wankel engine
* Pistonless rotary engine


External links

* [http://www.rkm-schapiro.org/demos.php Movies of RKM engines and compressors]
* [http://www.heise.de/kiosk/archiv/tr/2007/8/26_Der-Anti-Wankelmotor MIT Technology Review (German edition), 7 August 2007, "Der Anti-Wankelmotor" (The anti-Wankel engine)]
* [http://fazarchiv.faz.net/FAZ.ein Frankfurter Allgemeine Sonntagszeitung, 28 Oktober 2007, "Und er dreht sich doch noch" (And yet it turns)]
* [http://www.nkj.ru/archive/2008/5/ Наука и Жизнь (Science and Life), № 5 2008, "Овальные поршни, треугольные цилиндры" (Oval pistons, triangular cylinders)]
* [http://www.icsat2008.com ICSAT2008: International Conference on Sustainable Automotive Technologies (see Schapiro abstract)]

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