WO2014107628A1

WO2014107628A1 - Improved radial cam internal combustion engine

Info

Publication number: WO2014107628A1
Application number: PCT/US2014/010257
Authority: WO
Inventors: Donald James Duncalf
Original assignee: Kamtech I.P. S.A.
Priority date: 2013-01-04
Filing date: 2014-01-04
Publication date: 2014-07-10

Abstract

Embodiments of the present invention include a radial cam, internal combustion engine. The cam assembly, which is centrally located inside an engine block, has two-lobes and four raceways. Four cam-following bearings engage with the cam assembly's four offset raceways and are connected to the piston via a connecting rod. The connecting rod's movement is confined by a guide-way system which transmits the lateral forces placed on the cam-following bearings back to the engine block via a removable guide-plate. The connecting rods move the engine's pistons inside a plurality of cylinder barrels, which are dispersed in opposing pairs radially around the cam assembly.

Description

Improved Radial Cam Internal Combustion Engine

Donald James Duncalf

Field of the Invention

Embodiments of the present invention relate generally to internal combustion engines, and more specifically to radial engines which use a cam assembly to drive its pistons.

The concept behind the three main types of internal combustion (IC) engines, the Otto cycle, Diesel and the two-stroke, was first conceived in 1678 when a Frenchman named Abbe Hautefeuille proposed using gun powder to move a piston to obtain work. The Otto cycle engine in its present general form was first patented in 1861 by Alphonse Beau de Rochas. It was later perfected by Nikolaus Otto in 1876.

The first internal combustion engines developed were two-strokes. A modern two-stroke engine fires a fuel/air charge every time the piston comes to the top of its stroke. Instead of mushroom shaped poppet valves in or under the head, it uses ports in the wall of the cylinder, which are covered and uncovered by the piston to valve the incoming fuel/air and the burnt exhaust. As the piston descends it sweeps by a large port or hole which lets the exhaust gasses escape. As the piston continues to descend, pressure is built up under the piston, in the crank case which contains the air/fuel charge for the next explosion. As the exhaust gasses start to exit the cylinder the descending piston uncovers the bypass ports, which permits the now slightly higher pressurized air/fuel charge to enter the combustion chamber. Because the intake ports are much lower they open after and close before the exhaust port. At some speeds this allows large amounts of unburned fuel to exit with the exhaust. When the rising piston clears the exhaust port, the fuel air charged is compressed and it fires again producing power. The lack of a valve train and the fact that it fires every time the piston comes to the top permits two-stroke engines to be very light. However, their habit of putting large amounts of fuel through themselves unburned and their need to mix oil with the gas to lubricate their bearing on their connecting rods and crank means that they are very dirty and not very efficient.

A four-stroke engine fires every other time up. They have a system of mushroom shaped valves in the head which opens and closes in time with the moving piston. After their charge is exploded it pushes the piston all the way to the bottom of the stroke, which means more of the power can be extracted than in a two-stroke which pushes the piston only half way down. When the four-stroke's piston reaches the bottom the exhaust valve opens and the rising piston pushes the often still burning air/fuel mixture out of the cylinder. Because the temperature of the burning fuel can exceed the melting point of the valves and pistons if there is sufficient air, extra fuel is added to evaporate and cool these parts.

In order to completely burn this "cooling fuel" most modern engines use an air compressor to pump more air into the exhaust gasses between the engine and the catalytic converter. It is in the catalytic converter the extra cooling fuel is finally burned to form water and carbon dioxide. Back in the engine the exhaust valve closes and the intake valve is opened. The descending piston creates a vacuum which sucks in the next air/fuel mixture. When the piston reaches the bottom again, the intake valve closes and the piston rises, compressing the air/fuel charge making it ready to fire again at the top of the stroke.

A Diesel engine's cycles are very similar to a four-stroke engine. The two main differences is the higher compression ratio, which uses the heat of compression to ignite the fuel, and that a Diesel does not limit the air intake, only the fuel which is metered as it is sprayed into the compressed super heated air. Adding more or less fuel is the method of controlling the speed and power output. Diesel engines are more efficient because they don't need the extra cooling fuel. They almost always have sufficient air to burn the fuel which gives them a 15 to 18% advantage. Secondly, the more viscous Diesel fuel contains significantly more carbon atoms and therefore more energy per gallon than gasoline, and finally their high compression ratio increases their efficiency.

Compression is somewhat analogous to rolling a small ball up an incline, which is like "compression" then having the ball triple in weight, which is like "combustion" and letting it roll down and collecting the extra energy which is similar to and engine's "power stroke. In such a process, clearly increasing the height of the incline would increase the amount of energy collected on each power stroke. Practical steam engine development preceded the IC engine by approximately a hundred years. During this time the crankshaft became well established as a simple, easy to machine and effective mechanism to convert the reciprocal motion of a piston into rotary motion. The rapid acceleration and extremely high g-forces at the top of the stroke produced by a crankshaft are not a problem for a steam engine, which flashes high pressure steam against the piston then exhausts it at the end of the stroke, in most steam engine pressurized steam was applied to both sides of the piston. A crankshaft mechanism works well very in a steam engine; however, it has several drawbacks when used in an I C engine.

First, a crank system is impossible to dynamically balance because the shaking caused by the high speed reciprocal movement of an engine's pistons cannot be attenuate with spinning counter weights. While this is not a problem at the 300 or 400 rpm at which a steam engine operates, it can become a severe problem at ten times that speed.

Secondly, the snapping motion on each end of a crank-driven piston produces sharp peaks of g-forces on several parts, especially the bearing. Added to the stress is the explosive and often destructive force of the rapidly burning charge.

The third and perhaps greatest problem is the piston dynamic that a crank system imposes on the piston. In the 1850's lab experiments showed that the "ideal IC engine" should burn its charge under a more or less constant volume. In other words the piston should have a long dwell time at the top of its stroke.

The importance of slowly accelerating the piston when trying to harness the power of an explosion can be found in the almost cliche use of explosions in many movie scenes. The good guy's space ship accelerates so fast that the shock wave of the exploding flame front only gives him a jolt of acceleration, while the trailing villain's craft makes full use of the explosion's power greatly accelerating his craft. Sadly, a crank mechanism moves the piston much like the good guy's space ship. Rather than holding compression so the flame front can more quickly move through a smaller space giving time for the pressure to build, a crank-generated dynamic quickly accelerates the piston away, leading the flame front and extracting only part of the unleashed power. In the modern crankshaft driven engine the piston descends rapidly, leading the expanding flame front. Combustion is never fully completed inside most modern engines. At most speeds and loads the still burning charge exits out the exhaust valve down the exhaust pipe to the catalytic converter where the burning of the fuel is finally completed.

A crankshaft simply cannot provide an ideal dynamic when trying to burn an air/fuel mixture under pressure. Virtually all Pressure/Volume diagrams of the "Ideal IC engine" define combustion as a "Constant Volume Process". Only a cam can produce such an "ideal" piston dynamic.

As a reaction to these and other problems related to crank mechanisms, many early engine designers filed patents of engine designs which used cam assemblies to convert the lineal motion of their pistons to rotary motion of the output shaft. Such engine designs and patents are almost as old as the IC engine itself.

Some of these early designs failed because they did not provide sufficient resistance to the lateral forces brought against the cam followers by the moving cam assembly, or they simply let the cylinder wall resist such lateral forces like a crankshaft based engine does. Others failed simply because their poorly shaped cam profiles placed too much dynamic stress on components. Still others failed simply because no contemporary technology or materials existed to actually make the design into a practical engine. Overcoming these problems proved insurmountable to most of these early patents and few of these patents were ever built or marketed.

However, one of the first notable examples to be built and operated was the 1906 US Patent No. 817,905 by Frenchman Paul Daniel. His engine design was actually developed in the 1890s and made a brief showing at the 1900 Exposition Universelle in Paris, France where it was displayed and operated the last few days of that event.

Several years later in 1924 US Patent No. 1,654,375 by Paul Marchetti went into limited production and was marketed. Sadly the tragic death of the inventor and all the principals of the company put an end to that technology.

Another outstanding design that proved to be more robust than most contemporary crankshaft aircraft engines was the engine based upon the 1925 and 1927 US Patent Nos. 1,711,260 and 1,771,246 by Harold Caminez. It was the first engine ever to pass the stringent Navy endurance test for aircraft engines. At a time when the very best radial aircraft engine had a useful life of less than fifty hours before their crankshaft broke. The Caminez engine, which had no crank to break, proved to be virtually break proof.

While all three of these engines were enormous design and engineering feats, their failure was hastened because of three technical problems: (1) the lack of a well developed design that dealt with all the internal forces of a cam-centered engine, (2) the inability to machine a desirable cam profile to close tolerances, and (3) the lack of materials that could withstand the high contact pressures of the cam/bearing interface. Those familiar with the art are aware that new design tools as well as new manufacturing and material technologies have now removed these barriers. Computer Aided Design, or CAD systems can quickly resolve design problems in the planning stage, Computer Numerical Control or CNC machines can now be used to manufacture virtually any shaped cam to very high tolerances, and today's ultra-hard alloys as well as ceramic bearings have more than doubled the safe load of cam bearings, and at the same time these materials have permitted a large reduction in the weight of a cam engine's reciprocating parts.

The most relative and significant prior art are the two patents by the inventor and an associate. In 1996 the present inventor was granted US patent no. 5,553,574. The design of this patent followed the established practice of placing the main raceway and cam following bearing which ran on this raceway directly below the centerline of the connecting rod/piston assembly. See Fig 9 #104. However it differed from the previous inventions in two ways. Many early patents are designed to use the compression forces and/or the combustion forces to hold the cam following bearings on the cam assembly. Simple math makes it clear that these forces are not sufficient to the task.

So US Patent No. 5,553,574 makes use of two outer cam-following bearings on each side of its centerline cam-following bearing to hold the main cam-following bearing in contact with the cam assembly. The cam following bearings run across and are moved by the three raceway cam assembly as in FIG. 9. #102 & 104

Another short coming many early cam engine designs had was the use of the cylinder bore to counter the lateral forces placed on the lower end of the connecting rod by the rotation of the cam assembly itself. The connecting rod of the inventor's first patent, US Patent No.

5,553,574 FIG 8 # 106 used two widely spaced double-faced guide facets or lineal bearings on each side of the cam-following bearing to direct these forces back to the block. See FIG. 12 # 108.

In order for the whole system to work smoothly, it required that all three cams be in perfect alignment with each other when the engine was running. FIG 9 shows the long path of stress that the forces had to travel to keep the cam perfectly indexed. The cam had to be built heavy enough to resist being twisted out of alignment by the inertial and combustion forces transmitted through the moving connecting rod/piston assembly. This proved to be a challenge in actual practice. These slight misalignments would at some speeds place rotating forces on the lower end of the cam. To overcome the disparity of forces caused by these slight misalignments of the cam's three raceways, it required four widely spaced guide-way facets on the end of the connecting rod. While the design worked well, the connecting rod/piston assembly was very heavy. See FIG. 8 # 106

In 2004 US Patent No. 6,691,648 was an effort to lighten the moving mass of the connecting rod/piston assembly which would lower the dynamic forces on the whole system. While this engine used the general layout of US Patent No. 5,553,574 it replaced the case attached guide-way facets with a floating ring held in space over the "camshaft" with a system of pins which had one end inserted into the center of the connecting rods, and the other end inserted into the floating ring. This patent also used a very thin cam system made up of billeted plates with grooves carved into their face rather than broad raceways of US Patent No. 5,553,574. US Patent No. 6,691,648 also used thin double rings as cam followers rather than wider bearings. This design proved to be problematic as the lateral forces of the cam/cam following bearing interface again became born by the engine's cylinder walls, but it did demonstrate the advantage that could be gained by lowering the mass of the connecting rod/piston assembly.

It became clear that a method had to be invented to resolve the misalignment of the opposing cam surfaces caused by the long path of stress of the three raceway cam assembly of US Patent No. 5,553,574. See FIG. 9. The parallel raceways of the present invention attach directly to each other and machined together as in FIG. 10 #6 8. This solved the problem of misalignment, and resolved the twisting problem making it possible to use only one set of guide- way facets.

This would require going from the three raceways of patent 5,553,574 to four, two on each side as in FIG. 10 & 11. #6 & 8. This would also mean the cam following bearing handling the very high down forces could not be directly under the connecting rod's center line, as was the practice in virtually all earlier cam centered engine patents. Instead the cam following bearings would need to be spaced apart on each side of the connecting rod potentially bending the axle.

Regarding the accommodation of vertical load, the close tolerance that is achievable when the inward and the outward facing cams are machined together actually prevents the bending of the axle even when the engine was operated at speeds where the dynamic and combustion loads were sufficient to have bent the axle. In FIG. 11 the large arrows, represent the forces on the axle. The connecting rod's downward force on the center of the axle is converted into a shear load on the axle because the bending of the axle is resisted by the counter forces on the outer bearing. In other words the sum of all vertical forces acting on the axle is zero, so the axle is prevented from bending. This configuration permitted the use of lighter axles and lighter bearing than could be used in the three raceway cam engines, further reducing the reciprocal weight.

Some of the embodiments of the present invention address the short comings of the earlier radial cam engine patents and resolve most of the short comings of the traditional Otto cycle, Diesel and two-stroke engines. The prototypes of the embodiments of the present invention proved to be quieter, cleaner, smaller, more efficient and cheaper to produce than any existing engine technology.

In practice some embodiments of the present invention: (a) can burn a much leaner air/fuel mixture in an environment which lessens turbulence and reduces the wetting of the combustion chamber's smooth surfaces, (b) can manage combustion through better piston dynamics to more fully burn the fuel, (c) can lessen or eliminate the need for post burning of the unburned fuel and CO in a catalytic device, (d) can develop approximately twice the thermal efficiently of a standard Otto cycle engine (e) can provide more effectively controls and dissipate extraneous forces from the piston and connecting rod than existing designs, (f) can produce a more "ideal piston dynamic" to improve combustion and lower the dynamic bearing loads, (g) can provide for the efficient conversion of the piston's reciprocal motion into the output shaft's rotary motion, (h) can be inherently dynamically balanced at all speeds, (i) can have a large number of power pulses per revolution for smooth running, j) can provide a smaller, lighter and simpler design to minimize component parts, (k) can remove the need to put oil in the fuel (1) have a modular design to lower manufacturing and repair costs, and (m) can be able to be manufactured with the existing infrastructure found in most engine plants today.

Description

The pistons of some embodiments of the present invention can be housed within opposing pairs of stationary cylinders FIG 1 # 12 arranged in a radial layout around a central cam assembly having four (4) opposing but offset raceways to move the pistons. See FIG. 10 # 6 & 8. Some embodiments of the present invention's cam assembly can have a modified constant acceleration profile, which can provide a vastly improved combustion dynamic. This can cause the combustion event to take place in a more or less constant volume.

Different than 5,553,574 and 6,691,648

Some embodiments of the present invention include an improvement over prior art in general and specifically over US Patent Nos. 5,553,574 and 6,691,648 in the following ways: (a) The cam assembly has four wide raceways (FIG. 10) not three, as in US Patent No. 5,553,574. See FIG. 9 (b) The cam assembly of some embodiments uses a slightly modified constant acceleration profile, which greatly increases the dwell time at the top of the stroke to further improve the combustion dynamic, (c) The cam assembly's raceways are closely attached, which has the effect of reducing the twisting forces on the connecting rod and makes the cam assembly much easier to machine to very small tolerances, (d) The bottom of the rod guide's facet slots are joined together, which keeps the guide facet's from spreading under higher loads. See FIG. 13 (e) The connecting rod design of US Patent No. 5,553,574 has four guide facets or lineal bearing surfaces on its lower end. They were needed to overcome the twisting forces induced by cam assembly's misalignment when under load, which interact with the widely spaced outer cam-following bearings. Embodiments of the present invention can include only two guide facets because the newly invented four-raceway cam assembly places minimal rotating forces on the connecting rod/piston assembly. See FIG. 7 (e) Two newly invented connecting rod designs can be both capable of smoothly bearing all forces placed upon them by the running engine. See FIG. 8 #50 & 56.

The newly invented Connecting rods.

FIGS. 2, 3 and 8 show the newly invented oil lubricated connecting rod 50 configured to move on a thin layer of pressurized oil. Its two female guide facets move between two male guide facets on the guide plate. It weighs only 0.68 lbs. with its axle. Its lighter weight means the inertial load was so much less that thinner and lighter cam-following bearings are used, so the whole weigh reduction on the connecting rod/piston assembly was cut by close to 60%.

FIGS. 4, 5 and 6 shows how the newly invented roller guided connecting rod moves between two close fitting female guide facets, which are spaced apart just 0.1 mm wider than the diameter of the guide bearing. FIG. 4 illustrates the forces involved and the movement of the guide bearing, as it rolls up one side of the rod guide's guide facet slot and down the other in response to the forces placed upon it by the action and forces of the cam and the piston. In some embodiments, this invention can significantly reduce the friction between the connecting rod and guide facet.

Difference from earlier cam engines

In contrast to most of the earlier cam-centered engine patents, some embodiments of the present invention use a high-precision modified, constant acceleration two-lobed cam assembly to move its pistons. It can be machined on either a CNC milling machine or CNC lathe using a specially modified constant acceleration program, which defines the raceway's profile with hundreds of tangent radii. The dynamic of a crank can place very high inertial loads on the connecting rod/piston mechanism when it reverses direction at each end of the stroke. The G-force on the connecting rod/piston assembly of a modern auto engine can reach 7500 g's at just 5000 rpm. An advantage of using a cam assembly to move an engine's piston is that virtually any piston dynamic can be generated by altering the cam raceway's profile. The dynamic that produces the least G-force on the connecting rod/piston assembly can be one that places a constant inertial load from the center of the stroke to the center of the stroke. The profile for a constant acceleration cam can be calculated with the formula for Constant Acceleration CA= T² d, with T being time and d being distance.

The algorithm used to define the profile of some embodiments of the present invention's cam assembly incrementally increases and then decreases the d in each quadrant so as to very slightly increase the G-forces in those areas while also increasing the dwell time at the top and bottom of the stroke over what is provided by a true constant acceleration cam. Such a cam assembly can also provide many other advantages over the piston dynamic of a crankshaft engine.

Advantage Mechanically

The cam assembly profile of some embodiments of the present invention can produce less than half the peak inertial forces of a crankshaft-driven piston moved at the same stroke and speed. It can also produce an engine with perfect dynamic balance. The modified constant acceleration dynamic means the pistons, connecting rods and bearings may not be hammered with high G-forces at each end of their stroke. The lowering of these forces can permit further weight reduction, as the acceleration forces are held almost constant from mid-stroke to mid- stroke.

The crankshaft linkage of the modern engine can reach maximum mechanical advantage at around 50 degrees, and can have significant mechanical advantage at just 10 degrees. This quick rise in mechanical advantage can produce very high order torsional vibrations and requires rotating counter weights and an energy- absorbing flywheel to smooth them out. The mechanical advantage of some embodiments of the present invention's cam assembly can grow slowly and can be greatest from 20% to 80% of the stroke, which can virtually eliminate torsional vibrations. The actual torque transmitted to the output shaft can therefore be far smoother than a standard crankshaft engine. Another advantage of some embodiments of the present invention is the fact that in 4, 6 and 8 cylinder configurations, the periods of high mechanical advantage overlap, making for an extremely smooth-running engine. All of our prototype engines run as smoothly as an electric motor from idle to full speed. This can be a very important attribute in smaller vehicles and those coupled to electric hybrid transmissions or transaxles.

Advantage to two-stroke scavenging

The typical two-stroke has such a short dwell time on the bottom of the stroke that in order for there to be time for the ports to work properly the pressure of combustion must be released at the moment of maximum advantage, when the crank is at approximately 50 degrees past top dead center and the piston is approximately half way down the stroke. This happens when there is maximum pressure on the piston and maximum force on the crankshaft. See FIG. 14.

In any two-stroke engine, the replacement of the combusted charge with the new charge of air is a function of the size of the ports, their time open and the pressure differential between the exiting charge and the incoming charge.

Little can be done to increase the width of the ports as in the most advanced designs they practically ring the cylinder, but their effective size can be altered by raising or lowering them.

In some embodiments of the present invention, the cam assembly's dynamic can greatly increase the piston's dwell time at the bottom of the stroke, which means the ports are open for a much longer time than in crankshaft engine.

Other features of the present invention which can improve the scavenging process is the floor plate, which is placed under the piston FIG 2 #54. This plate can be shaped so as to improve the air- flow in the pre-combustion space, located directly under the piston, but it can also increase the pressure of the incoming charge. The longer dwell time and far higher pressure in the advancing pre-combustion charge can permit the ports to be lowered from the standard position of approximately 50% of the stroke down to around 87% of the stroke. These improvements have made for an engine which idles down to a slow speed without the hit and miss firing of the standard two-stroke.

Other benefits of the floor plate 54 include no piston scuffing because the floor plate holds the connecting rod and piston exactly in the center of the bore. The plate can also provide an oil-tight seal, so unlike other two-strokes, there is no need for oil in the gas, so some embodiments of the present invention can be significantly cleaner than most four-stroke engines.

Advantage to Thermal Efficiency

Lowering the ports can also greatly improve the thermal efficiency of some embodiments of the present invention. This benefit was directly observed in the prototype, where this lowering of the exhaust ports resulted in a reduction of the exhaust temperature from over 800° C to less than 450°C. Much of that extra 350°C of heat energy was converted into work, as combustion pressure continued to push the piston 75% farther down the stroke, through the cam assembly's moment of maximum advantage. This allowed more of the fuel's energy to be transmitted through the piston to the output shaft. The engine also ran much quieter as the exhausting pressure was much lower when it burst into the environment.

Most of the afore-cited advantages can accrue from the long dwell time at the bottom of the stroke, but surprisingly there can be even more advantages to be gained from the long dwell time at the top of the stroke.

Advantage to Combustion Dynamics

The modified constant acceleration cam assembly can provide little mechanical advantage for several degrees before and after top dead center. This attribute can allow combustion to be started much earlier than in a crank driven IC engine without causing counter- rotation. Being able to start combustion earlier can have many benefits. Most "Pressure Volume" diagrams for the ideal IC engine show combustion to be a "constant volume process". The advantages of having the combustion in an IC engine take place on under a more or less constant volume are manifold. The maximum flame front speed is the speed of sound which increases with pressure. So holding a constant volume means a faster flame front can traverse a much smaller space. Completing the burn before the piston's decent means greater pressure on the piston and more of the heat of combustion can be converted into work.

Advantage to the Combustion Process

A side benefit of more complete combustion is that little or no CO and unburned fuel is exhausted. But complete combustion requires that there be sufficient air to burn all the fuel. While this is possible inside a diesel's combustion chamber, which does not limit the air charge, it cannot be attained inside the combustion chamber of the standard Otto Cycle engine. Here's why:

The ideal air to fuel ratio (AFR) is referred to as "stoichiometric" or λ (lambda). This ideal ratio supplies exactly the right amount of air to oxidize the CsHis*, or gasoline, into H₂0, or water and C0₂, or carbon dioxide..

This ideal AFR for *pure gasoline is calculated to be about 15 : 1.

Gasoline's stoichiometric calculation is:

1 mole C₈Hi8 and 12.5 moles of 0₂. (C₈+8 0₂ = 8 C0₂ and ¾ + 9 0₂ = 18 H₂0) 12.5 moles 0₂ = 400 units mass.

Air contains 3.76 times as much nitrogen as oxygen (79%/21%): (3.76) (12.5 moles) = 47 moles N₂. 47 moles N₂ = 1316 units mass.

1316 + 400 = 1716

1716.599 / 1 14.232 = 15.03 : 1

But in virtually all naturally-aspirated gasoline engines (no supercharging or turbo charging), the normal AFR range from 12.5 - 13.3 : 1 or a λ of 0.85 - 0.90. This rich AFR is needed by modern IC engines to cool their valves and their pistons. A stoichiometric air/fuel mixture burned in the confines of the typical engine far exceeds the melting point of aluminum (660°C). The outcome of burning a rich charge is that first virtually all the volatile hydrogen molecules are burnt into water, but then there are simply not enough oxygen molecules to fully oxidize all the carbon molecules. This 10% to 15% lack of air is the main reason there is so much pollution produced by a standard Otto cycle engine. To finish the burn, most modern engines are coupled with an air compressor which injects air into the still burning exhaust which is then forced through a catalytic converter where the unburned fuel and the CO is burned into C0₂ and a little more water.

The typical combustion chambers in an Otto cycle engine have the internal shape of a deformed pancake at TDC. Its surfaces are irregular with sharp valve edges above and irregular valve pockets below. These sharp edges and irregularities cause turbulence at the flame front as hot gasses roll across wetted areas and combustion flashes on and off, as the piston makes a rapid decent. This shape and these dynamic conditions greatly increase the heat transfer to chamber's surfaces lowering thermal efficiency. Over 40% of the fuel's energy goes into heating the heads, pistons, valves, cylinder walls and exhaust system in most Otto cycle engines. The combustion chamber of some embodiments of the present invention use ports to valve the charge in and out of so it lacks the irregular surfaces that produce so much heat transfer and combustion inefficiency.

The long dwell time at the top of the stroke produced by some embodiments of the present invention's modified constant acceleration cam assembly allows time for the combustion event to take place in a more or less constant volume. The smooth surfaces and longer dwell time at TDC mean that turbulence is greatly reduced, as is conductive heat loss.

Some embodiments of the present invention such as a spherical combustion chamber create a more ideal environment for combustion Yet the recycled burned charge, which is common to many two-strokes, keeps the event cool enough to inhibit the formation of NOx. This is far more Ideal than the 150 year old Otto cycle engine, which powers much of the world's IC engine applications. Besides wasting fuel with its inefficient combustion, the conventional IC engine is also wasting enormous amounts of heat energy when it fails to convert that heat into work.

Conventional IC engines under load can exhaust gasses at temperatures of 850° to 1000°C (over 1800°/)· The typical auto engine sends about 40% of the fuel's heat out the exhaust pipe.

The United States Department of Transportation's Research Board concluded that the typical modern gasoline powered automobile uses approximately 13% of its fuel to actually drive the car down the road. An enormous 87% may be wasted, much of it because of the above-cited reasons. The longer dwell time and lack of valves of some embodiments of the present invention allows for use of one or more lean burn systems without fear of damage to the engine, and the long dwell time and the lowered ports permits more complete combustion to take place before the piston extracts the power and vents the burnt charge.

The dynamics of some embodiments of the present invention are inherently balanced. Each piston has a matching counterpart of exactly the same weight and moves on the same center line in an opposite dynamic. The movement of every piston is equal in time, force and dynamic to its paired piston. For every movement and force in the engine, there is an aligned equal and exactly opposite force to counteract it. This coupled with the eight power pulses per revolution (twice the number of a V-8) permit some embodiments of the present invention to rival an electric motor in smoothness.

The balance and smooth dynamic performance of some embodiments of the present invention are achieved by design and not by the addition of power-robbing rotating weights or shafts. The small size and flat configuration of some embodiments of the present invention offers much greater flexibility of use in many applications, both motive and stationary. Some embodiments of the present invention can be configured so that it can bolt up to virtually any application presently using two-stroke, Otto cycle and/or diesel engines both motive and stationary. Some embodiments of the present invention engine are easy to design and

manufacture, such as two, four, six or eight cylinder and/or even stacked or coupled units.

In conclusion some embodiments of the present invention are cleaner, smoother, quieter, lighter, more powerful for its weight and significantly less expensive to build than the Otto cycle or the standard two-stroke internal combustion engine.

While some embodiments of the present invention have been described by means of specific features or attributes, there are many modifications and/or variations which could be made by those skilled in the art without departing from the scope of the invention, as set forth in the following claims.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a view of an embodiment of the present invention's accessory side.

FIG. 2 is an exploded view of the main parts of an embodiment of the present invention configured with the oil lubricated guide plate.

FIG. 3 is a cutaway of the oil lubricated guide plate of an embodiment of the present invention.

FIG. 4 is a cutaway of the roller guided connecting rod/guide plate interface of an embodiment of the present invention.

FIG. 5 is an exaggerated illustration of the forces and direction of roll of the roller-guided embodiment of the present invention's connecting rod/guide plate interface as it rolls up one side of the guide-way facet and down the other, as the cam assembly acts upon the cam-following bearings.

FIG. 6 is an isomeric view of the bottom of the roller-guided embodiment of the present invention's connecting rod.

FIG. 7 is a bottom view of the roller-guided connecting rod system's four cam-following bearings and a cut-away of the female guide-way facets in the roller guide plate of the roller- guided embodiment of the present invention.

FIG. 8 is an isomeric view of the connecting rod design of US Patent No. 5,553,574 and the connecting rod design of two embodiments of the present invention.

FIG. 9 is an isomeric cut-away view of the three raceway constant acceleration cam assembly of US Patent No. 5,553,574 and isomeric of its cam assembly half.

FIG. 10 is an isomeric cut-away view of the four raceways modified constant- acceleration cam assembly of an embodiment of the present invention and an isomeric of its cam assembly half.

FIG. 11 is a cross section view showing the guide roller and the cam-following bearings of an embodiment of the present invention which, diagrams the vertical forces on the connecting rod's axle.

FIG. 12 is an isomeric view of the engine block half showing the integrated four up guide-way facet system of US Patent No. 5,553,574.

FIG. 13 is an isomeric view of the oil lubricated guide plate for a four cylinder embodiment of the present invention, which has configured into it four guide-way facet slots which contain the engine's four rods.

FIG. 14 is an illustration comparing the placement of the exhaust port of an embodiment of the present invention with the port placement of a typical crank driven two-stroke engine.

DETAILED DESCRIPTION OF THE EMBODIMENTS

In the following description, numerous details, such as specific component shapes and quantities, are set forth in order to provide a more thorough description of some embodiments of the present invention. In other instances, well known components and manufacturing methods are described in general terms, so as not to obscure any embodiments of the present invention unnecessarily. The scope of the invention should be determined with reference to the Claims.

Some embodiments of the present invention relates to a novel, two-stroke, radial, internal combustion engine with pistons being reciprocated by a modified constant acceleration two- lobed cam assembly, having four precision machined raceways, which in some embodiments can be made of hardened, high carbon steel or other appropriate material. The unit in the production version could be investment-cast, stabilized, hardened and ground to very close tolerance. Some embodiments of the present invention are now described with reference to the drawing appended hereto:

FIG. 1 illustrates the accessory end of an embodiment of the present invention. A preferable embodiment of the present invention has four radially-disposed cylinder barrels 12, which are bolted 14 to a metal engine block 16 which has its end closed with an end cap 18 held in place by means of several bolts 20. Each cylinder barrel 12 has an intake port 22 and an exhaust port 24. The outer portion of the intake port 22 is flanged to accommodate a standard reed valve system and standard intake manifold, as is common to the art. The exhaust port 24 is used to route the hot exhaust gasses safely away from the engine. Bolted to the top of each cylinder barrel with multiple bolts 26 is a cylinder head 28 which retains the compression and combustion of the engine. Located in the center of each head 28 is a sparkplug 30 which serves to ignite the air fuel mixture, as is common in the art.

A liquid cooled embodiment of the present invention is illustrated in FIG. 1 as indicated by the "water pump" cavity 32 and the water ducts 34 which are cast into the engine block end cap 18. Other embodiments of the engine may be air-cooled, in which case fins would be attached to the exterior of the cylinder barrel 12 and head 28. Some embodiments of the present invention's output shaft 36 can deliver power out either or both ends, as the application may require.

FIG. 2 illustrates the major interior components housed in the block 16, and inside the cylinder barrel 12. Beginning at the top of FIG. 2 is the output shaft 36 which is held in the center of the engine block 16 and the end cap 18 by large anti- friction bearings 38. Centered on the output shaft 36 and just below the end capl8 is the top half of the cam assembly 40. Below the top half of the cam assembly 40 is a guide plate 42 which, when installed can be held to an attachment shelf 44 inside the block 16 with locating pins and counter-set machine screws.

When so assembled, the centerline of each guide- way facet slot 46 of the guide plate 42 can be precisely aligned with the center of the cylinder barrel 12. Continuing down the output shaft 36 is the bottom half of the cam assembly 48, which can be press fit onto the keyed output shaft 36 as well as attached to the top half of the cam assembly 40.

The connecting rod 50 has four cam-following bearings 52 fitted onto its axles 54. The assembled connecting rod 50 is then fitted into the guide plate's guide-way facet slot. 44 When assembled, the cylinder floor 54 has the connecting rod 50 piercing its center. The piston 56 is attached to the top end of the connecting rod 50 via a threaded attachment. The piston is fitted with standard piston rings, as is normal in the art. Lastly, the cylinder barrel 12 and head 28 are bolted to the block encasing the connecting rod 56 and 50.

FIG. 3 illustrates an embodiment of the present invention which uses an oil-lubricated connecting rod 50 which is held in alignment with the center of the cylinder's bore by means of its guide-way facets 60 which engage with the matching guide-way facets on the 46 guide plate 42. The drawing further illustrates how the round top of the connecting rod 50 is further held in the center of the cylinder bore by its engagement with the cylinder floor plate 54. Four cam- following bearings 52 engage with the upper cam 40 and the lower cam's 48 raceways. Also illustrated are the retaining caps 62, the block 16.

FIG. 4 illustrates an embodiment of the present invention which uses roller guided connecting rods. The view is similar to FIG. 3. The lower end of the roller guided connecting rod 58 makes contact with the guide plate 42 via a large narrow center roller 60. All other interior engine parts are the same in this embodiment of the present invention.

FIG. 5 is an exaggerated illustration of the forces and motion of the guide roller 60 as it runs up and down the guide-way facet slot in the guide plate 42. The actual clearance is held to 0.1mm + 0.02mm. When operating and under increased speed and load this clearance slightly increase however the oil film creates a substantial cushion to the parts as the dynamic viscosity of the oil film increases as the roller moves at higher velocities.

FIG. 6 shows the lower end of the roller guided connecting rod 58, the guide roller 60, the cam-following bearings 52, and the retention caps 62.

FIG. 7 shows is a view of the roller guided connecting rod 58 from the bottom, illustrating its relationship to the track in the guide plate 42. Also shown are the cam- following bearings 52 and the retention caps 62.

FIG. 8 illustrates the inventor's three embodiments of the connecting rod. On the left is the connecting rod of his 1996 US Patent No. 5,553,575. When made of steel it weighed in at 1.34 lbs. In the center of FIG 7 is the oil lubricated connecting rod 50 of the current invention, which when made of steel weighs .68 lbs. or only 50.7% the weight of the US Patent No.

5,553,574 connecting rod. On the right is the roller guided connecting rod embodiment of the present invention 56, which is even lighter at .54 lb when made of steel. Making the connecting rod/piston assembly lighter with better design has allowed the engine to attain higher operating speeds and therefore more power output per weight.

FIG. 9 illustrates the inventor's cam assembly design from his 1996 US Patent No.

5,553,574. In the foreground is one half of the cam assembly. The larger illustration shows the cam assembly's profile when cut on a bias. This cam assembly when manufactured of cast steel machined and tempered weighed in at 26.2 lbs without a shaft. It needed to be this heavy to maintain alignment of the three cam profiles. This is because the path of stress is very long and the high dynamic forces generated by the reciprocation of the much heavier connecting rod/piston assembly of that invention caused misalignment between the inner cam and the outer cams, if the path of stress were too thin. FIG. 9 # 102 & 104

FIG. 10 illustrates the cam assembly design of an embodiment of the present invention. Lowering by over half the weight of the connecting rod/piston assembly and redesigning the cam assembly permitted a significant lowering of the cam assembly. The cam of some embodiments of the present invention have a shorter "path of stress" between the inner and outer cam assembly profiles than the cam of patent No. 5,553,574. See path of stress FIG. 10

FIG. 11 is a cross section view showing the guide roller and the cam-following bearings of the roller guide- way system embodiment of the present invention which diagrams the vertical forces on the connecting rod's axle.

FIG. 12 illustrates the inventor's integral with the block guide-way facet system from his 1996 US Patent No. 5,553,574. This system proved problematic as dynamic forces tended to open up the clearance on the guide-way facets causing excessive wear on the guide-ways.

FIG 13 illustrates the guide-way facet system of an embodiment of the present invention. A large ring in the center of the guide-way facet plate ties the lower end of the guide system together maintaining the distant between the two bearing surfaces under all load conditions. This is the important feature of this design. While such a ring could be cast as part of the engine block machining the guide ways could present a problem. Making it detachable has eased several manufacturing and assembly issues that were present in the design of US Patent No. 5,553,574.

FIG. 14 illustrates the typical two-stroke exhaust port placement as compared to some embodiments of the present invention. The typical two-stroke's exhaust ports are normally placed around 50% of the stroke. The higher pressure that is attainable because of the present invention's floor plate and a longer dwell time provided by a modified constant acceleration cam assembly permits the exhaust port to be lowered significantly and still breathe well. Lowering the exhaust ports greatly increases the duration of the power stroke. This feature is largely responsible for the vastly improved efficiency of some embodiments of the present invention.

In some embodiments, the present invention discloses a two-stroke internal combustion (IC) engine configured as a radial. As in all radial engines, the present engine has its cylinder barrels and connecting rod/piston assemblies spaced evenly around the edge of the engine block. FIG. 1 # 12 The engine's power emerges through an output shaft located in the center of the engine block. FIGS. 1 & 2 # 36

Like most internal combustion engines, the present engine uses a moving piston #56 and a fixed cylinder barrel #12 to confine the dynamic force of combustion and convert that force into movement and work. The main difference between some embodiments of the present invention and standard crankshaft engines is the mechanism used to convert the piston's lineal movement into the rotary motion of the output shaft. #36 An embodiment of the present invention uses a cam assembly #40 & 48 with four parallel raceways instead of a crankshaft for this lineal to rotary conversion of the piston's movement. The back and forth movement of the piston is transferred to the rotating cam assembly through four cam-following bearings, two on each side of the connecting rod. FIGS. 2, 3, 4, 6 &7 #52 These cam-following bearings are mounted on an axle which goes through the end of the connecting rod opposite the piston. FIG. 2 # 54 The cam- following bearings are moved closer and farther away from the center of the cam assembly as its raceway move against the cam-following bearings, thereby moving the connecting rods and the pistons inside the cylinder barrels. FIGS. 1 & 2 # 12.

Both crankshafts and cam assemblies produce very high lateral forces when used for a lineal to rotary conversion. In a crankshaft driven engine those lateral forces are directed up the connecting rod and against the cylinder wall so that it becomes the means to confine and redirect the crankshaft's high lateral forces. The resulting piston scuffing produces a significant friction loads on the engine.

In some embodiments, the present engine is configured so as to not produce any piston scuffing. Instead of directing those lateral forces up the connecting rod and against the cylinder wall, in some embodiments, the present engine uses a guide system or lineal bearing which is centered exactly where the cam assembly places such forces on the lower end of the connecting rod. FIG. 3 # 60 & 46 A guide-way systems are configured so as to confine movement on two axes but allow for low friction movement in the third axis. The present engine can use a thin guide-way system to reach down between the cam assembly's two halves and transfer the dynamic load that is placed upon the cam-following bearings by the moving cam assembly back to the engine's block.

A guide- way system is composed of static guide facets and dynamic guide facets. The dynamic guide facets of an embodiment of the present invention FIGS. 3 & 6 # 60 & 61 are configured on the end of the connecting rods. These guide facets face into and away from the direction of the cam assembly's rotation and are centered over the axle, which bear the cam- following bearings. This configuration receives and redirects the lateral force produced by the cam assembly's movement against the cam-following bearings at the exact point of its generation.

The static half of the guide-way system is configured as part of the removable guide plate, wherein the two guide facets of each guide slot are connected together at the plate's center. FIGS. 2 & 13 # 42 This prevents the spreading of the guide facets under conditions of high speed and high loads. FIGS. 2,3,4 & 13 # 42 Both the moving and stationary surfaces are machined to close tolerance so that no matter how much force the advance of the cam assembly's raceways places on the lower end of the connecting rods the guide-way is able to resist and/or redirect the movement in the axis of the cylinder bore.

In some embodiments, the piston end of the connecting rod is held in the center of the cylinder barrel by a closely fitted bushing and seal in the engine's cylinder floor. This feature keeps the rod FIGS. 2, 3&450 and piston 56 in the center of the cylinder 12 and directs the forces of combustion that come against the piston 56 to be efficiently translated into rotary force through the cam following roller 52 into the cam 40 & 48then into the output shaft 36.

This cylinder floor also greatly improves the breathing of the engine and keeps the lubricating oil in the engine block and separate from the incoming fuel/air charge. This feature also prevents the blow-by of products of combustion from contaminating the lubrication oil.

The present invention can by manufactured in many forms and sizes, and it can efficiently burn several different fuels while costing less to build, being smoother, lighter, cleaner and cheaper than other engine designs.

Claims

1. A radial internal combustion engine comprising,

an engine block;

an output shaft,

wherein said output shaft is rotatable coupled to said engine block; a cam assembly,

wherein said cam assembly is fixedly coupled to said output shaft, wherein said cam assembly comprises two first offset raceways facing said output shaft and two second offset raceways facing away from said output shaft, wherein said first offset raceways are parallel to said second offset raceways, wherein said offset raceways are configured to be closer to said output shaft on one or more first sections of said cam assembly's perimeter and farther from said output shaft on one or more second sections of said cam assembly's perimeter;

a plurality of cylinder barrels,

wherein said plurality of cylinder barrels are coupled to said engine block;

a plurality of pistons;

a plurality of connecting rods,

wherein said plurality of connecting rods are coupled to said plurality of pistons, wherein each connecting rod comprises a first end and a second ends,

wherein said first end of said connecting rod is coupled to a piston of said

plurality of pistons,

wherein said second end of said connecting rod is coupled to an axle in an axis perpendicular to said connecting rod,

wherein said axle comprises a plurality of cam-following bearings, wherein said cam-following bearings engage with said offset raceways of said cam assembly,

wherein said second end of said connecting rod comprises two opposite facing connecting rod guide facets;

a guide plate, wherein said guide plate is coupled to said engine block,

wherein said guide plate comprises a plurality of parallel guide facets, wherein said parallel guide plate's guide facets are configured to engage said connecting rod guide facets.

The engine of claim 1,

wherein the guide plate's guide facets have a male profile,

wherein the guide plate's guide facets are lubricated with pressurized oil, wherein said guide facets are perpendicular to a centerline of said connecting rod and a centerline of said axle said connecting rod is configured as guide facets, wherein said guide facets are perpendicular to a centerline of said connecting rod and a centerline of said axle and said connecting rod,

wherein the connecting rods' guide facets' are configured with a female profile, wherein movements of each said connecting rods is confined through engagement with said guide plate to the axis of a centerline of each said cylinder barrels. The engine of claim 1

wherein the guide plate's guide facets have a female profile,

wherein said connecting rods is having a centerline and two ends,

wherein the connecting rods' second end comprises two ring shaped appendages spaced apart from the connecting rods' centerline,

wherein the centerline of said ring shaped appendages is perpendicular to the

centerline of the rods,

wherein hollow axles protrude outward from each of said ring shaped appendages, wherein said axles bear the cam- following bearings which engage with the said raceways of said cam assembly,

wherein the centerline of said axles are aligned with said centerline of said ring

shaped appendages,

wherein bearing pins are inserted into the axles and fill the gap between the ring shaped appendages,

wherein a guide following roller is mounted between the ring shaped appendages and rotates about the bearing pin, wherein the guide following roller constitutes the connecting rods' guide facets, whereby movement of said connecting rod is confined to the axis of the centerline of said cylinder barrel through engagement of said guide following roller with said guide plate.

4. The engine of claim 1 ;

wherein said cam assembly reciprocates said pistons according to a predetermined algorithm,

wherein said algorithm provides for a longer dwell time at the top of the stroke and the bottom of the stroke.

5. The engine of claim 1

wherein the engine uses water to cool the cylinder barrels and head.

6. The engine of claim 1

wherein the engine uses air to cool the cylinder barrels and the head.

7. The engine of claim 1

wherein the engine has a two lobed cam assembly to move the pistons which has a modified constant acceleration profile which provides for a longer dwell time at the top of the stroke to improve further the combustion dynamic and allow for more ideal combustion event which takes place in a more or less constant volume.

8. The engine of claim 1

wherein the engine has a standard compression ratio, spark plug ignition using

gasoline as a fuel with an electronic carburetor system.

9. The engine of claim 1

wherein the engine has a standard compression ratio, spark plug ignition using

gasoline injected into the port just before it closes with a computer controlled electronic injection system.

10. The engine of claim 1

wherein the engine has a standard compression ratio, spark plug ignition using

gasoline injected directly into the cylinder after the exhaust port closes timed with a computer controlled electronic injection system.

11. The engine of claim 1 wherein the engine has an increased compression ratio sufficient to effect compression ignition using Diesel fuel with fed directly into the cylinders with mechanical injectors.

12. The engine of claim 1

wherein the engine has an increased compression ratio sufficient to effect compression ignition using Diesel fuel fed directly into the cylinders with computer controlled electronic injectors.

13. The engine of claim 1

wherein the engine has an increased compression ratio sufficient to effect compression ignition using gasoline as a fuel which is fed directly into the cylinders with a computer controlled electronic injection system.

14. The engine of claim 1

wherein the engine has an increased compression ratio sufficient to effect compression ignition using compressed natural gas as a fuel with a computer controlled electronic injection system.

15. The engine of claim 1

wherein the engine has an increased compression ratio sufficient to effect compression ignition using liquefied petroleum (LP) gas as a fuel with a computer controlled electronic injection system.

16. The engine of claim 1

wherein the engine has an increased compression ratio sufficient to effect compression ignition using bio gas as a fuel with a computer controlled electronic injection system.