Harmonic Reciprocating Heat engine HRHE and Pulling Piston Engine PPE

HARDWARE DESCRIPTION

Schematics illustrate the major components of a 2-cycle reciprocating engine as they are modified to meet the needs of an engine, as a pump, a combustion chamber, a lightweight structure, etc.

With the exception of a simple modification on the piston crown and skirt, there is hardly any difference from the components of the conventional engine, a mere rearrangement of the same constituent parts, so that structural integrity and thermodynamic functioning fall in phase.

As long as the thermodynamic functioning is a temporal sequence of events, a course of events in the course of time, such as:

· a pumping of the working gases,

· a heat exchange among gases and walls,

· a sequence of physical processes preceding and preparing the combustion,

· a combustion, which in itself is a succession of delays, chemical chain reactions, etc,

this pulling piston engine, PPE for short, suggests a rearrangement of the known components of the state-of-the-art engine, so that the objectives of a heat engine are

better met; on the grounds that with all this string of successive events involved, each taking its own time, a combustion is a time consuming physical and chemical process and the time granted by a particular mechanism may simply be inadequate.

Among those objectives ought to be:

· Air polluting gases and CO2 reduction,

· Fuel economy; gas guzzling reduction,

· Environ friendly manufacturing; lesser mass; involvement of plastics,

· Reliability, simplicity, small bulk, and lightweight,

· Balance, smoothness, and comfort,

· Opportunity for further applications of the reciprocating engine, as a prime mover; as a result of the combination of a diminished weight, improved fuel economy and a sufficiently balanced mechanism.

The reliability, fuel economy, balance, lightweight, etc, brought about by suspending the piston, like a suspension bridge, allows the engine the potential of becoming the prime mover of a portable flyer; a propeller plus an engine plus a fuel tank.

The featuring of these constituent parts, as they are rearranged to meet the needs, allows some sort of description of the engine.

A review of the main items of the engine, their functioning and their functional and structural differences, as compared with the respective components of the state-of-the-art, follows:

1. Crankcase

2. Main bearings

3. Crankshaft

4. Crank pin

5. Con rod, big and small ends

6. Slider and slider ways

7. Camshafts, valve train, balance.

8. Piston crown, piston crown rings

9. Piston pin, piston rod, piston rod seals

10. Cylinder bottom, exhaust ports and headers

11. Cylinder

12. Air pump beneath the piston crown

13. Air pump intake means

14. Transfer ports

15. Reed valve

16. Spark plugs and injectors

17. Cylinder-bottom to cylinder connection

1. CRANKCASE

With the exception of the piston ring, all the rest moving parts of the engine, are enclosed and essentially isolated into this crankcase.

Oil leakage and gas blow-by, to-and-fro the crankcase, can occur only through piston rod seals and valve guides.

Given the thinness of both stems, oil contamination by unburned fuel and combustion products seems diminished, resulting in increased life expectancy of oil. Oil quantity is reduced, because of the smaller area of the overall oil film. No cylinder head is calling for oil. No oil between piston skirts and cylinder walls. No oil problem when the engine changes orientation; tumbles, rocks, flips, skyrockets, nosedives…

Assuming permanent tension along the power train, namely the piston is suspended like a suspension bridge, there is a chance of increased clearances in the bearings of pins and journals combined with oil of increased viscosity. Since the load on the bearings is of constant direction, a lash, a wider clearance does not involve any playing of the pin inside the bearing while the thicker oil is cushioning the impacts.

Another potential, offered by the permanent direction of the forces, is the chance of flexible bearings. Such bearings, like the big and small ends, affords a flexing according the load tending to increase the oil film area, and thereby the capacity of the bearing, in direct relation to the imposed instant force.

This flexing of the bearings, apart from transiently increasing their bearing capacity, provides an extra cushion means for the impact loads from combustion and inertia; a shock absorber with additional working for the sake of reducing any idle-oil-film. An oil film of variable area, proportional to the load for the bearings is only allowed when the direction of the forces keeps constant.

At the same time thicker oil, and wider areas at the locations of the heavy thrust, enables the slider-ways to cushion their own impacts. Neither the distance, along the slider-ways, nor their surface need to be constant, unlikely a cylinder bore which is doomed to a constantly plain and full touch, even at piston places of no loads at all.

As for the lubrication of the oil ring, just a wet bore is all it needs.

As for all the bearings, plain journal bearings and forced lubrication are allowed

2. MAIN BEARINGS

In a Diesel and in a non-misfiring spark engine the load, along the con rod, is a constant tension. It contains and limits the loaded material, of the engine body, only between the upper half of the main bearings and the cylinder bottom. The rest of the engine body is rid of any gas pressure or heavy inertia load, as well as any thermal expansion loads. This is where the slider-ways are. Along with their functioning as the thrust bearings of the sliders of the piston pin, they constitute a structural part for bridging the loaded cylinder bottom with the loaded half of the main bearings.

Gas and inertia impacts are limited in the material which lies between the upper half of the main bearing and the thrust point of the slider-way, which is short and compact, and involves no vibrating or ringing components like cylinders block or crankcase wall, etc. There is no restriction for the slider-ways to be of any form and have any cutaway. Neither their structural duties nor their frictional efficiency impose limits.

3. CRANKSHAFT

In the schematics of the 4-cyllinder in line it is not drawn any balance weights on the camshaft. A couple of balance webs on at least one of the camshafts balances the only left moment of such a 0-90-270-180 degrees crankshaft, which is nothing else than the crankshaft of the classical V-8, 90 degrees engine, even firing and essentially full balanced engine. A couple of balance weights on one camshaft, or both, suffices for making this 4-cylinder engine as balanced as the aforementioned V-8 conventional.

Thanks to its 2-Cycle operation it is not uneven firing, has the same number of combustion per revolution as the V-8, 4-Cycle. Counterweight webs are not designed on the camshafts of the 4-in line, as they are in the 3-inline and the 2-inline, because this method of balancing the inertia moment left over is a KAWASAKI ’s patent. In any case, inline engines can hardly rid of their heavy crankshafts because of the inertia and combustion torques involved, their modes of torsional vibration …

4. CRANK PIN

In the multi-cylinder V-engines a master road system could be drawn as well. Since the pulling nature of the rod forces allows for the width of the big end being smaller, the common pin arrangement is simpler than master rod, etc, not only on simplicity considerations. A four-cylinder star engine is as fully balanced as a V-8 conventional; without any balance problem. The slender the big-end the more the rods a pin can accommodate and the smaller the offset between cylinders. A simple comparison of this star engines with the radial of the state of the art proves their relative simplicity and thereby the reliability brought about by this arrangement. The forward step here is the common crankcase, which is beyond the possibilities of the conventional 2-C, without an external pumping system. In the state-of-the-art such systems involve supercharger in line with turbocharger which is, in itself, more complicated, heavy, bulky, troublesome, etc, than the whole PPE, let alone its peaky performance owing to the inline connection of components which are more or less peaky in themselves.

5. CONNECTING ROD, BIG AND SMALL END

The point here is that, at least for 2-Cycle engines, the compressive loads are small as compared with tension loads either from gas or inertia forces. The heaviest possible compressive inertia force is as small as half the tension inertia force. In a sense, the tension stressing along the power train provides similar potentials as the suspension bridge is provided by the constant direction of the gravity.

A second positive characteristic appears to be the fact that the geometry, in itself, imposes no limit on the stroke/bore ratio, which may lead to long con rods, in the search for top efficiency by enhancing the compactness of the combustion chamber, even with higher compression ratios. The absence of considerable compressing force enables the con rod being made as a simple blade. It enhances its endurance in bending, vertical to the crank axis at the expense of its bending resistance on the other plane, where it is useless, taking advantage from the absence of any threatening column loading.

And, of course the third characteristic; the breathing of this engine is valve-free.

Both bearings are stressed outwards which allows them a flexibility which potentially broadens their loaded oil-film-length in direct proportion to the instant load, while keeps the oil film short at the times of lower loading.

It also allows for wider clearances without involving impact loads, noise, etc.

Thanks to the pulling nature of the forces, the width of the big end is determined only by the bearing capacity, which in a plain bearing depends on the oil-film breaking point. The smaller the width of the slice, the more rods can share the common pin.

6. SLIDER AND SLIDER-WAYS

It has long been known that, of all the problems involved in engine design, that of securing a reliable structure to withstand the loads imposed by gas pressure, inertia forces and thermal expansion is the toughest. Slider-way material looks like taking care of all of these problems. That’s because all of them; gas-loads, inertia-loads, thermal expansion loads and heat conduction, all of them, are contained within and are propped up by the material around the slider-ways and by the slider-way material itself.

It appears that in this friction-connected slider and slide-way pair, having the same problematic with the cam and cam-follower pair of the conventional valve train, the knowledge from the-state-of-the-art, about reducing friction, thermal loads, etc, is rather fully applicable.

The essential advantage rests with the presence and plentitude of the oil and the relatively favorable conditions within the crankcase.

Unlike a piston skirt-cylinder assembly, the slider-ears are not subject to any heat expansion problems, firstly because of their little dimensions and secondly because of the lower temperature changes they are subjected inside the crankcase. There is not danger such as a piston slap lurking here.

On the contrary, the oil may retain increased viscosity for shock cushioning considerations.

The elementary view is that, so long as a thrust force cannot be avoided, owing to the slanted con rod, the worst way to counteract is by means of the skirt of the piston of the conventional engine, constrained to thrust against the cylinder walls, being already:

· Heated by gases, and subjected to temperature difference along the axis.

· Heated by skirt friction and ring friction, generating temperature difference around the circumference.

· Subjected to heat expansion, altering clearances.

· Require extra ring for oil control, which in turn increases friction loading…

Slider ways provide an extra assistance, for cooling considerations, as they can conduct heat away from the cylinder bottom and prevent generation of hot spots all across bottom area; the only location of the PPE with thermal loads.

Eliminating the need of liquid cooling results in more than halving the weight, cost, complexity, components, etc, even for the conventional state-of-the-art.

As a result, a really simple engine turns out to be an air-cooled engine.

Drawings make clear that slider-ways involve neither structural nor functional or manufacturing, or assembly difficulties.

Since the mere duty of the slider is to take up the thrust force of the leaning connecting rod, it is its simplicity and lightweight that matter most. Plain slider ears, formed as projections of an as simple as possible pin, seem the best compromise, simply because it appears to make the machining of the slider-ways the easiest; a mere flat milling machining, cut through the material among the headers.

Of course it can be further treated, in order to diminish friction and enhance cooling. For instance, the plain and flat slide-ways can be bored, cut away, shortened or otherwise machined so that only the necessary area is left at any place of the travel, determined by the thrust force and speed of the slider at this particular place.

Since the combustion takes place while the slider is closest to the crankshaft, the fresher and therefore most viscous oil, and the plentitude of oil falls straight on the slider ways ends, where the thrust impact from the combustion are the most severe to necessitate a cushioning.

On the other hand, instead of being at the farthest from the crankshaft end and at the hottest region of the engine, as it is the case in the conventional engine, here, the sliders are thrusting the coolest part of the slide-ways during the combustion.

All of them sound more valuable for absorbing the Diesel combustion impact, nevertheless, for any case, it is better having the heavy loads on the cooler surfaces and on the fresher and viscous oil. The opposite is what occurs in the conventional engine; at the end of the outwards stroke, where little is left to take place, right there the cylinder wall is the cooler and the oil film the stronger.

7. CAMSHAFTS, VALVE TRAIN, BALANCE

In a 2-C, the valve gear train needs to sustain its reliability at twice as much a camshaft speed, as compared with a 4-C, as long as the goal is some two times the specific power of the state-of-the-art 4-C.

Unless extra long stroke/bore ratios are considered, it has long been known that the limiting speed will be that of the valve train rather than that of the power train, in this kind of the through-scavenge engines. This problem calls for an enhanced precision and higher rigidity for the valve train, which in turn, calls for higher precision and accuracy, which, in its turn, dictates a valve train with as few as possible components along with connections as backlash-free as possible. The camshafts in a 2-C, being of first order, provide for a further function; as balance-shafts for balancing first order inertia forces and first order moments, and potentially first order torques, which makes the precision and the reduced backlash of the drive more valuable.

Variable timing makes more sense in a precise and backlash-free valve train.

Camshaft counterweights save the weight of distinct balance shafts and drives, their bearings, the friction involved, etc.

Top priority for an engine, which is supposed to be of fewer cylinders as being 2-cycle, hence unbalanced inertia forces and moments are going to come into play. Also for an engine which is supposed to minimize friction and lubricant and which is supposed to be capable of transcending gravity by sustaining a man while being as lightweight as to be portable.

It seems that a portable flyer appears more realistic by having PPE as its prime movers also on reliability, and comfort considerations.

Since a single cylinder appears to suffice for most requirements, each camshaft carrying a balance weight rotating the opposite direction provide as much balance as acceptable under most services limitation. It only takes the one camshaft being driven by the other.

In some drawings rollers are involved, as cam followers to ease the drawing. Although rollers are widely being used as cam-followers in the art, there is not any shortage of solutions, such as radial valves or just thinner cams, smaller buckets, etc.

Drawn rollers are meant to mark the needs for elaborated design to face the high speed of the 2-cycle valve train system. Although rollers may involve some sort of increased inertia, their rolling may be more valuable for spreading the friction load over the cam and cam follower, at least according the principles of the Flash Temperature theory.

The state-of-the-art suggests that valve motion is most likely the limiting factor of engine speed. In the effort to reach the speeds of the racing 4-C the installation of more than 3 valves involves little further complexity and cost.

For racing purposes, the sort answer is that the number of exhaust valves can be increased until the valve gear train speed fall under its endurance limit.

DUCATI ’s desmodromic valve train might allow higher camshaft speeds on the following grounds:

· Belts, sprockets, interposed shafts, etc are not involved.

· The valve train involves only the gears, the camshafts, the cam followers, the valves and the springs, that is only the rigid parts and only those involving no backlash.

· The flexible and inaccurate components of the system simply do not exist.

· Since the power consuming components such as the intermitted shaft with all its bearings, gears and sprocket loads are eliminated the friction of the system is reduced, let alone lubrication complexity.

· Oil plentitude, oil thrown off all around by the revolving components cure the inherent problem of the system owing to the number of the parts involved, in particular, follower supports, follower friction point with valves etc.

· Since the lift of the exhaust valves need not be as high, the sideways thrust imposed by the closing rocker on the valve stem is less severe.

· The elimination of the belts and the interposed shaft seem sufficient for a considerable increase of the speed of the valve gear train.

· These exhaust valves necessitate no retainer-spring; the gas makes their job.

Of course the eminent advent of the ceramic valves, announced by Mercedes, and their less than half weight, as compared with their steel counterparts, is a more realistic breakthrough to the problem of the twice-as-high-speed of the valves and their rings in the 2-C engine.

8. PISTON CROWN, RINGS

The piston shape selected in the figures is meant to provide the best possible streamlining for the transfer flow. The symmetry brought about by a central suspension, apart from making the machining the simplest, it is advantageous both structurally and functionally.

Structurally, central suspension appears to enhance the pressure/weight ratio attainable whilst involves the least thermal expansion problems.

Central suspension allows a potential flexing in bending, which, along with the resilience in tension allowed to the rest of the power train, tend to prove substantial for such purposes as cushioning and smoothening out the shock of the impact due to combustion and inertia forces. Heat expansion does cause the smallest stress concentration all across the piston area, and diminishes any expansion problems. The absence of any interference of piston and valves has always been the case in the 2-C.

It also sounds as a variable-compression; a means for detonation suppression at peaking loads and reduction of top pressures and perhaps the rate of pressure rise in Diesels.

But over and above, this piston carries the experience gained on the test bed, during the measuring of the HRHE. It has since single-handedly proved the best component of the mechanism not merely as functional but as a structural component, as well.

Symmetry has always proved an advantage.

Piston ring lubrication, which at first may seem as problematic as in a 2-C conventional, has proved anything but that, perhaps because of the minute quantity of oil necessary and only for merely keeping the bore wet, just between ring and wall.

Oil lost either through crankcase ventilation, channeled into a couple of rows of holes around the bore, and thrown off the piston rod, seem more than adequate for the ring.

This oil can, either by being thrown off, by the rod as it emerges during expansion, driven by inertia, or provided through the crankcase ventilation at holes on the bore or by more elaborated ways as spray injection, though they appear surplus.

Oil clinking on the rod may be assisted by dimples on the surface of the distant end of the rod if more oil is to be thrown off…

Cylinder has the potential of being tapered towards cylinder bottom in the pursuit for reduced ring tension at locations where sealing is more or less useless. No matter how simpleminded it may sound, it stands to reason that any potential blow-by of unburned gas and combustion products can cause no harm to any piston skirt, oil film, crankcase oil and materials, cylinder head materials, intake valve fouling etc. This blow-by is bound to immediately return to the combustion chamber along with the next transfer gas without even the chance of approaching the reed-valves.

A tapered cylinder put in a HRHE gave measurable increase in the power at full loads, greater gains in part load consumption, idling at lower speed and at an even lower consumption, than proportionally estimated. Wide, piston to cylinder, clearances tested in HRHE engines showed little effect on the performance, with the exception of signs of piston slanting and leaning against the walls, but there exist strong compressive forces and column loading. As long as the ring can sustain the added heating caused by any potential blow by, a tapered cylinder just makes sense.

BMW ’s announcements on its Hydrogen engines allow some theoretical remarks.

A cylinder with that high concentration of water vapor tends to face precipitation, at least on the walls, which will be severe with a cold engine; starting up, cold weather...

This condensation of water at the cylinder walls of a 4-C engine tend to dilute the oil make foam, leak into the crankcase…

In a 2-C PPE the only way for such a contamination of the crankcase oil is through the piston rod seals.

On the other hand because of the smaller, some 15%, power concentration of a hydrogen charge, it rather tends to increase the number of cylinders of a 4-C as compared with a gasoline engine. The resultant engine mass, along with the water jackets, etc, only makes the warming up period too long, which though less polluting than in gasoline remains a source of consumption and most likely a cause of lubrication problems following the condensation of the vapor over the chili walls.

For both gasoline engine and Diesel the new standards impose tests with a cold engine instead of a heated up, as it was the case until recently.

The engine mass and the water jackets being the causes of a delayed heating up has been given solutions like thermally isolated water jackets, by BMW, exhaust gas bags by Saab etc. The simpleminded view is for an engine with as small a mass and rid of liquid coolant as to reduce the warming up period.

The potential of a tapered cylinder in a PPE deserves a mentioning because the whole

geometry seems to point towards very long stroke/bore ratios, and because both look that simpleminded and naïve to attract more attention just for this reason.

For competition, aero engines, etc, where calls for piston speeds well above 30 m/s has always been present, the answer is that the only constituent part under abuse is the ring; tapered cylinder reduce the ring/cylinder affairs. In essence it is equivalent to reducing the ring speed, at least according Flash Temperature theory.

Through scavenging has been well sought by conventional engines even though it is always associated with extreme complexity and narrowed power band range. A single turbocharger cannot cope with transient conditions, a single supercharger proves inefficient because of waist exhausted gas.

Nevertheless through scavenging efficiency has nothing in common and it is beyond comparison with cross scavenging from any perspective.

The opposition of the experts is likely to focus on the cylinder lubrication. In terms of this, the following can be uttered.

· Under current practice, a single ring crown appears sufficient. Most 2-C conventional use single ring despite the risk it involves for skirt seizure. Such risk simply does not exist for a piston, which does not touch the bore. Testing of the HRHE has not shown any such tendency, even under the heaviest loads, even when the piston apparently leaned on the bore because of poor alignment, rough machining, etc.

· Single ring associated with low ring lands above the ring allows a 2-C piston crown ring-lands being thin and streamlined as viewed by the transfer gas.

· Tapered cylinder reduces ring friction; compressing a ring, where there is no longer any useful pressure to seal against, makes no sense.

· There is a built-in lubrication by means of the piston rod. Piston rod inevitably carries on its surface some oil doomed to be thrown off as the rod goes its travel. Some of the oil may direct and reach the bore wall.

· Another built-in oil provider is the crankcase breather. Blow-by gas leaking into crankcase and the rest of crankcase ventilation may be discharged through a row, or a couple of rows, of holes at an appropriate location of the cylinder. Of course it provides for the combustion of the crankcase fumes as well.

The guess and hope is of achieving sufficient gas sealing without involving any ring.

To this goal the advantages appear to be

· The simplicity of the cylinder; as simple as a pipe.

· The easy connection of cylinder and cylinder-bottom allowed by the absence of neither radial nor axial forces. The heavier force seems to be that due to the air pump gas pressure.

· The symmetry of the heat loads over any cross section of the cylinder due to the almost full geometrical and gas-streams symmetry. Only the limited number of the exhaust valves is to blame for spoiling the full symmetry.

· The full geometrical symmetry of the piston crown.

· The lower heat loads on piston crown and cylinder due to the through scavenging.

· The lower exhausted gas temperatures due to higher compressions, leaner mixtures and the timely integration of the combustion.

Test bed measurements with HRHE engines show increased endurance for the rings as compared with the respective conventional engines. As most rational explanation appears the cooler cylinder wall thanks to the elimination of the piston skirt thrust.

Under the principles of the Flash Temperature theory the following can be uttered;

· Since the cylinder temperature is higher at around mid stroke where the higher temperatures are generated by the product thrusting force times piston skirt speed, it is also there, where the rings have their top speed and thereby the worst conditions for themselves and for the oil film.

· The rings of the HRHE, being sliding at cylinder walls of not such heat loads, from thrusting shirts, showed improved longevity.

On this basis it is estimated that even without lubrication the PPE could work as long as the transfer stream is found capable of providing the cooling of the ring as it crosses the transfer ports during the transfer stroke.

The potential remains open to be practically achieved that this piston-bore assembly can work without any rings at all. It is not unlikely that materials for the bore and the piston crown will be found allowing clearances providing the sufficient seals without

involving any rings, etc. Sufficient in the sense that any leak here is just a loss of pressure and not a threat for the mechanism and for the oil.

The blow by gas ends into the pump wherefrom it is bound to return to the combustion chamber. Excessive blow by of hot gas causes no problems such as oil film burning, overheated shirts, friction increase, seizure, etc.

There will always be the potential of a ring-less sealing, mainly thanks to the radial symmetry of both the cylinder and the piston crown.

9. PISTON PIN, PISTON ROD, ROD SEALS

It seems that the designer is almost free to choose any articulation, fixing, etc for realizing this connection.

The general term “slider” is called to include any reasonable arrangement capable to provide the trusting force determined by the con rod angle, which is the force that the piston skirt of the conventional engine undergoes.

Further requirements of such a slider are small weight for containing inertia forces, and simplicity for reliability considerations and of course diminished friction.

It seems reasonable to apply the knowledge from the valve/valve-guide pair to tackle the sealing problems between piston-rod and cylinder-bottom. Since the best seal known is the poppet valve seat, a valve-shaped guide seated in a valve-seat-like hole may extend so far as to provide low temperatures for potential seals where it proves necessary. It sounds sufficient a poppet-valve-like sealing for the piston rod. The presence of the rod into the combustion chamber will attract most of the opposition.

To be sure, it would be better without that rod therein, however the question needs to be what got for what paid. In terms of the current objectives and problems of the combustion engines, this piston rod offers a whole perspective for fuel shortage, environ deterioration, global worming, air transport, portable flyers potentials, etc.

As for the sealing of the rod face, it seams, hitherto, best to rely on the flexing, of this valve-like guide under gas pressure, for taking up the slack

Thanks to the thinness of this delicate rod, the thermal expansion can cause little change in the clearance between rod and valve-like rod guide hence this play might be as tight as to enable sealing only by flexing under pressure. This play can be kept closed, during high-pressure periods by flexion of the guide under gas pressure.

One thing is sure; such a skirt-less piston has been the best working part of the Harmonic Reciprocating Heat Engines, HRHE for sort, manufactured and tested in late 80’s in the search for a reciprocated… hence of compact chamber… still full balanced… hence WANKEL-like engines…

These HRHE show a performance this better, that can only be attributed to the extra time granted to their combustion, indeed the WANKEL’s time interval.

Throughout idling, part loads and full loads, low or top speeds, the HRHE is superior, at least as compared with the conventional, whose parts have been used as they were; cylinders, heads, carburetors, ignition etc. The mere absence of vibrations, of any order, is the ultimate temptation for the rider to accelerate to engine speeds beyond the limits of the cams, chains, etc. The single cylinder HRHE using parts of YAMAHA XT 250, 2-Valve model has far better performance, economy, idling quality, etc, than the conventional itself, let alone the full balance of a WANKEL.

While a conventional piston pin and its lubricant is doomed to undergoes a high temperature and an inhospitable environ, worsening in 2-C, where oil injection, etc are not available, in a PPE there are not such difficulties, in the first place.

Since the piston pin and the slider means keep away from hot regions and are allowed the crankcase oil cooling, lubricating, cushioning, etc effects, their dimensions, weight, area, friction, etc are favored accordingly.

10. CYLINDER BOTTOM, PORTS, HEADERS

Full symmetry is feasible for the cylinder-bottom, which is the equivalent of the cylinder head of a conventional 2-Cycle, exhaust-valve engine.

As viewed by the gases, a 4-Cycle conventional is a highly asymmetrical architecture. Both gases, the leaving exhausted gas and the entering fresh gas are doomed to follow paths, streams and trajectories that are far from being thermodynamically efficient, are doomed to touch walls of the wrong temperatures, etc, and even worse at the wrong timing.

Beyond any doubt, through scavenging is an advantage, especially when it comes at the expense of nothing. The built-in air pump provides quality and simplicity beyond other sorts of pumping equipment, mainly because of a better timing.

Exhaust poppet valve has been overwhelmingly dominated over sleeve valves, rotating valves, etc in the state-of-the-art, on the basis of its self-sealed effect.

Exhaust ports and pipes have plenty of space to spread out, like daisy petals, allowing generous areas for cooling and eliminating any point of material concentration with the likelihood of local overheating, reducing the asymmetry their mere existence imposes

A simple comparison with DAIHATSU 2CD shows how simpler this arrangement is in terms of the thermal load diffusion and cooling system simplicity.

The air pump of the PPE provides more flow while the free-expanding arrangement of the exhaust ports seems to provide sufficient cooling by exposing the headers into air.

DETROIT DIESEL, DAIHATSU 2CD and the similar arrangements have to resort in the exhaust gas for their volumetric capacity and to liquid cooling for their survival.

Apart from their complexity; involving turbochargers and superchargers, etc, there is a cylinder head which need to be cooled while it is fully surrounded by exhaust gas which in itself must be kept hot; mutually opposing requirements, a vicious circle. Water jackets are built surrounding exhaust pipes, a full contradiction with any sense of energy economy, simply because there is no way out.

The hope is that along with the availability of a supplementary cooling, by means of the oil of the crankcase, air-cooling is sufficient, at least under the limitation put by most services. The aim is to eliminate liquid cooling systems. For higher ratings, for top performance, racing etc, liquid cooling always remains a resort.

11. CYLINDER

The SULZER RTA, and similar engines with cross head, get rid of the piston thrust on the cylinder walls, whilst enables through scavenging. PPE rids the engine body as well. In all the engines of the art the whole engine body throughout, from cylinder head to main supports, whole is under the combustion forces, under the inertia forces, under the heat expansion forces, and under the thermal loads. In PPE, only a small part of the engine, merely the part contained between the bottom and the upper half of the main bearings is under these loads.

The rest of the engine structure is substantially rid of any stressing. This fact reduces the engine material only to what is necessary to withstand the gas loads, inertia forces and thermal expansion forces only within this portion of the engine body. The rest of the engine can be made thin hence light, etc. Plastic materials, for the whole engine beyond transfer ports, face neither forces nor temperatures, even without any cooling means. The engine is cool for two main reasons. First because hot gas keeps far from

induction means and second because such a cool intake gas results in cooler cycle and third because of cooler exhausted gas due to the first and second reasons.

The absence of axial forces, across cylinder-bottom and cylinder connection, rids this assembly of the bolting means, thread bosses, etc, and of the consequences of their presence there, namely the thermal problems following the geometrical asymmetry they cause in the region.

Yet, what SULZER, MITSUBISHI, and the other cross-head have in common is what the short stroke reciprocating engines lack - the WANKEL even badly - is a compact combustion chamber, somewhere where the fuel have little relationship with the walls and plenty of affairs with the working gas.

The simpleminded view is that what the fuel has to do is to heat the gas, not the walls, the farther it stays from the walls the better for the cycle. A WANKEL and an over-squared piston engine can’t help forming chambers where the combustion is doomed to creep just on the walls.

Either the question is about the propagation of a flame throughout a prepared mixture or it is about the combustion across a Diesel spray the combustion is doomed to take place just next to the walls or on the walls itself.

But while the best that should happen is to heat the gas, without heating the walls, the worst happens; the fuel is wasted to heat the walls.

Such a combustion, which is creeping and sweeping the walls is not only a waste of energy, it necessitates the cooling system of the state-of-the-art engines, which tend to be more expensive and troublesome than the entire engine.

In a flat attenuated combustion chamber the spray can do little to avoid the walls, and the flame even less to avoid occurring over the walls or sweeping them.

Small strokes imposed by the breathing difficulties of the 4-cycle and by the column loading of the con rods is the evident culprit.

It makes no sense at all the Diesel spray falling on the piston crown, its reasonable course seems to be a free flight across the chamber until it gets evaporated, nebulated, atomized and mixed with the oxidant. Central injection and chamber in the piston crown are rather gross compromises than devised solutions.

PPE can afford the long strokes that make the combustion chambers capable of heating the working gas, not their walls, just like in the large marine engines.

Sharp sprays in the large diesels afford this over 55% fuel efficiency, far above any other known prime mover. Full similitude is applicable with PPE; even the plain chambers of the long marine engines of the 55% efficiency can be scaled-down copied thanks to this geometry, no need for wells on the piston to contain the spray, neither cutaways for the valves to allow some kind of overlap.

As long as efficiency and performance is a result of the suitability of the geometry of the chamber in terms of combustion requirements, of the flow capacity of the induction system… this spatial geometry offers another perspective. PPE provides another temporal geometry as well.

Unlikely the large marine, locomotive, stationary, etc, diesels, in a small diesel everything tends to work against it. The chamber is too thin to call for cutaway in the crown to house the spray, but even so combustion can’t help occurring at the squeeze area. Valves have not room to open to allow overlap, though the engine is longing so much for great flow allowed only with wide overlaps and lifts, not only for combustion considerations.

12. THE AIR PUMP BENEATH THE PISTON

Every cylinder has its own inherent and inherited and built-in pump. Unlikely conventional with so many problems associated with any attempt to connect more than one rod to the same crankshaft this engine puts no limits. Star engines like those of the drawing, either as they are shown here or as master-rod arrangements, find no problem in using the simpler known crankshaft.

It takes only to compare a radial of the state of the art with those star engine to readily see the economy in all respects; weight, bulk, front area, simplicity, reliability, power etc. The elimination of the push-roads is a major step in itself.

Apart from having each cylinder its own air pump, it provides a through scavenging which is by far the best known in the state-of-the-art. Neither puts any limit on the stroke-bore ratio. Great ratios of stroke to bore have that top efficiency, which only in marine diesels like SULZER RTA and the like of its kind is met; brake-efficiencies well above 50%, no other prime mover is up to.

At least the advantages of the 4-C engine crankcase combined with an individual air pump for each cylinder is the case in the PPE. The small breadth of the con rod big end, allowed by the pulling loading, makes it easier to have more rods in one crank- pin. Single piston ring reduces the piston ring land height to allow easier and streamlined transfer flow in the effort of minimizing gas mixing.

Unlimited intake area for the pump; the free side of the pump is available for induction purposes. No restriction on where Reed valve petals can be located, even disc valves have better geometry to adapt. With such a pump the physical processes may be dealt with in line each at a time, according to its particular requirements:

· Better for the induction to be smooth and slow as the air enters the pump, mixing, atomization, evaporation, etc better wait later stages, a wide intake is what is here the major consideration.

· At the next stage, that of the transfer flow, the streams generated by the transfer ports can take over the mixing, atomization, vaporization etc without worsening the mixing with the residual gas, owing to the advantages of the through scavenging over the cross scavenging.

· What is not completed yet is left for the next stage, that of the piston dwelling at higher densities and temperatures before the initiation of the chain reactions making up combustion.

A major advantage for all of them is the long stroke allowed by both the structural geometry of the arrangement and the pumping potential of this pumping arrangement.

13. AIR PUMP, INTAKE MEANS

The state-of-the-art suggests reed valves. A bell-mouth formed on the cylinder end

faces no restrictions of diameter and read valves located therein are provided with unconstrained area.

These read valves are allowed to function as three way petals opening towards cylinder during late exhaust and early compression and towards pump the rest of the time.

Only an axial compressor is allowed such a wide and free intake; only the one end is occupied by the crankcase the other end is available to be devoted to the bell-mouth with unhindered dimensions. Between the trumpet and the transfer ports there is a cylindrical space where a Reed block can be located, or even move if variable dead volume for the pump is formed. This availability of room for the Reed blocks and

their move along the cylinder axis, without involving bulk and dimension increases while allowing simply implemented unlimited variable compression is not available in an configuration where both ends are occupied. A conventional engine has its one end occupied by the crankcase and the other by the cylinder head.

The open end of the engine is formed as a streamlined funnel and right after and inside the petals of the Reed valve can find more area than in any conventional arrangement.

Since any swirl, turbulence, etc, can be created later, by the transfer ports, it seems reasonable that the flow through the bell-mouth can be as slow and smooth as to neither cost any pumping loss nor to generate and set off any noise, at least an aerodynamic one. As long as the absence of valve gear chains reduces mechanical noise and the absence of inlet porting reduces aerodynamic noise, what is left is the reed petal noise to be faced in the intake system.

14. TRANSFER PORTS

Another obvious characteristic of the engine is that the only area bound to be hot is the cylinder bottom and the cylinder strip next to the bottom, the farther the cylinder points from the bottom the cooler they are. At the distance of the transfer ports the cylinder is rather cool or at least at temperatures allowing the ports and the rest being made from plastics etc. It results in lighter components and less heat transferred to the fresh gas. Transfer ports are short as they depend on the ring lands length, in the case of single ring they get shorter while the piston almost fully streamlined.

15. THREE WAY REED VALVE