TECHNICAL FIELD This invention pertains to the field of heat engines. 5 In greater particularity this invention pertains to the field of reciprocating heat engines.

For further characterization, this invention pertains to a new type of reciprocating heat engines, of internal or external combustion, with two main characteristics: 10 (1) The pistons reciprocate harmonically and

(2) The connecting rods of these pistons move independently of any slider.

- This invention also pertains to the balancing of such engines.

15 - Also pertains to a specific way for scavenging such engines in case of two-stroke cycle operation.

- Also pertains to the crankcase sealing from the cylinder walls of such engines.

- Also pertains to several design modes for carrying 20 out the invention.

BACKGROUND ART The class of periodic heat engines consists of:

- The conventional reciproca ing engines of the type 25 "crankshaft-connecting rod-piston".

- The rotary wankel engine.

- The unconventional types of rotating or reciproca¬ ting or any combination of them. The unconventional types are either under development or they are abandoned. No such

30 type has now any wide or significant use.

The Wankel rotary engine is for specific sizes and for special use. It possess a small percentage in the total number of engines production. That's because of some considerable problems. Such problems are the cooling, the 35 lubrication, the sealing, the problem of the thermal stresses and above them the small efficiency and the emissions.

Thus, remains the conventional reciprocating engine to predominate.

It is used everywhere, for any size and duty, as two 40 or four-stroke either as spark or as compression ignition. However, it has its disadvantages.

These disadvantages are what the unconventional types try to eliminate but, so far, they introduce other worse problems. These disadvantages are : 45 1) Low specific output for power and torque per unit of weight, volume or displacement of the engine.

2) significant dynamic loads that imply crucial stress distributions in the engine components, especially in crankshaft, in connecting rods, on bearings e.t.c.

? 50 3) Low level of working smoothness.

4) Considerable friction forces between the most connections and surfaces, especially at high speeds.

In spite of these troubles, the conventional reciprocating engine has some superior advantages which give 55 it the superiority against the other types of periodic heat engines.

The most important of them are :

1) The great experience amassed through the centuries (since the Watt steam engine).

2) The use and the approval at any size and duty, as two or foui*—stroke, either as spark or as compression ignition in cases of internal combustion.

3) Proved reliability and durability.

4) Compact combustion and expansion chamber.

5) Easy and efficient sealing. 6) Cooling and lubricating systems of great efficiency and quality with regard to the absence of local heat stresses.

7) Small cost and high efficiency. DISCLOSURE OF INVENTION

This invention introduces a new type of reciprocating heat engines, called harmonic engines, with the following two special features :

1. The harmonic reciprocation of their pistons. 2. The slider free motion of the connecting rods.

It also introduces full balance of such engines. It also introduces a sealed separation of the crankcase from the cylinder wall.

It also introduces a system for scavenging such two- stroke internal combustion engines by using the behind the piston chamber which is sealed from the crankcase.

It also introduces special design modes for the realization of such engines.

" Advantages as regards the prior art " In the case of the conventional reciprocating heat engine the movement of the piston and the connecting rod lack symmetry and is complex enough to give accelerations of several directions and magnitudes.

These accelerations imply inertia forces and torques that are difficult to be balanced, and stress distributions in the components that are difficult to be suffered and great friction forces either due to the pressure into the cylinder or because the inertia forces.

The architecture itself does not help the use of long stroke engines (which may achieve better thermodynamic efficiency, lower emissions e.t.c).

On the other hand the suggested type of engines has, among others, the following advantages:

1) Harmonic reciprocation of the pistons which is a motion of smaller maximum accelerations and at the same time is a motion giving the chance for a full balance.

2) The slider free movement of the connecting rods eliminates forces on the cylinder walls from the piston rod assembly. 3) The around the T.D.C. (top dead center) motion of the pistons, where the most important thermodynamic processes happen, has a time function providing better thermodynamic behavior.

4) For the same reason, in the case of four-stroke cycle function, the valve timing can be chosen (without introducing any other problem i.e. idling operation, low speed

operation e.t.c.) to give more valve overlap (angle or time when all the valves are ope i) and so, to provide better exhaust and intake processes which give better volumetric efficiency. 5) Increased specific power and torque per mass unit and per volume unit and per displacement unit.

6) The most suffering parts with the greatest loads and the complex stresses (i.e connecting rods, crankshafts e.t.c. ⁾ have been changed to reduce their loads and to enable the engine to run faster.

7) The mass of the moving parts is significantly smaller. So, in combination with the smaller maximum accelerations and the simplest movement, the maximum speed of the engine can be even higher. θ) Since the action of the piston against the cylinder walls, either from inertia or from pressure loads is much reduced, the cylinder block can be much lighter.

9) The harmonic reciprocation of the piston plus the absence of bending forces on the block and together with the full balance of the moving parts result into a running smoothness (low level of vibrations, low level of noise e.t.c) that only with the Wankel rotary combustion engine can compare.

10) The forces between piston and cylinder walls are much smaller, especially at high speeds. The same happens to the forces on bearings. The number of bearings is reduced.

The reduction of friction forces give chances for higher speeds of revolution and possibilities for use higher stroke/bore ratio. 11) The spark advance can be smaller, as well the injection advance in compression ignition can be smaller.

Inversely, with the same advances the available time for burning in both cases is longer. So better efficiency and higher speed are achieved. 12) Because of the friction reduction on bearings and on the cylinder walls the harmonic engine has improved reliability and durability.

13) Smaller height of the engine - for the same stroke - because of reduced lenght of piston skirt (so reduced cylinder wall length) and because of smaller sum of piston length and connecting rod length.

14) In the case of two-stroke internal combustion engine the isolation of the crankcase from the behind the piston space, provides a lubrication system for the crankshaft, rods e.t.c similar to that of four-stroke cycle engines. Moreover another way for controlled scavenging is provided by changing the "dead" volume behind the piston and so changing the scavenging process.

15) In the case of adiabatic engines - that seems to be the future for the internal combustion engine - the harmonic engines offer:

-lower inertia stresses

-elimination of piston slapping and impact loads -elimination of piston - cylinder wall forces (operation even without lubrication between piston and cy1 lnder wal 1 )

-ability for complete isolation (sealing) between crankcase (where lubricant may exist) and cylinder wall (case similar to the isolation between crankcase and the behind the piston space in the two-stroke engine, described below).

BRIEF DESCRIPTION OF THE DRAWINGS In figures from 1 to 9 several mechanisms, for the change of the rotation of a shaft into a harmonic reciprocation, are illustrated. In figure 10 an illustrated gradual transition from the conventional reciprocating engine to the harmonic reciprocating engine is exposed. The components of the two systems are functionally identical (correspond to one by one). So the same names for components of the new mechanisms are used.

Figures 11 and 12 show the form (in section view and in an exploded form) of a two-cylider in-line harmonic engiπe.

In figures 13, 14 and 15 is given the form (in several section views) of a four-cylider flat harmonic engine.

In figure 16 is shown a three dimensional view of the moving parts and of the block of an eight cylinder engine (this engine is actually a combination of two engines like that described in figures 13, 14 and 15) In figures 17 and 18 is given the section view of two- cylider flat (boxer) two-stroke engine which uses scavenging process by means of the sealed -from the crankcase- space behind the piston.

In figures 19 and 20 is given a section view of a single-cy1 ider harmonic engine with a mechanism suitable for very long strokes.

The numbering of the components that has been used in the figures for the description of the harmonic engine is complex. Consists of a number and a letter. The number corresponds to the specific component while the letter corresponds to the specific part of the component.

For instance, in the figure 11 :

1A —> balance weight of the connecting rod 1. 1C —> gear wheel of the connecting rod 1. IF —> end pin of the connecting rod 1.

2A —> balance weight of the crankshaft 2.

" Mechanisms"

In the figure 1 the rod KA has a length KA=r and is rotating around the center K with an angular velocity ω. The rod AB of the same length AB=AK=r is joined at the end A with the rod KA while its other end is forced to move along the axis YY' (by the use of a slider, for instance). In this case the rod KA is the crank and the rod AB is the connecting rod. The end B of the rod AB is performing a harmonic reciprocation as far as the rod KA is rotating with constant angular velocity.

Here exists an i πdefiniteπess when the A is passing through the axis XX' . Due to AK=AB=r the triangular KAB is isosceles, so

KB = 2 * KA * cos( ^Λ AKB) = 2 * r * cos(f)

If the angular velocity ω is constant, then f = ω # t + fo, so finally

KB = 2 * r * cos(ω * t + fo) which is the expression of the harmonic reciprocation. f : angle of KA with the axis YY' ω : angular velocity of KA fo: initial angle f, when t=0 . The figure 2 shows a way to eliminate the points of lndefl niteness of the mechanism of figure 1. At the immovable notches B1,B2,C1 and C2 "button" at the right time the projections B and C. So the points of l ndefl niteness vanish.

The figure 3 shows a combination of two mechanisms like it of the figure 2. They are revolving with opposite angular velocities (vectors). At this mechanism neither points of l ndefl niteness exist, due to the cooperation of the immovable notches T1,T2,T3 and T4 with the projections B1,B2,C1 and C2, nor sliders a re necessary to keep B along the axis YY' . So, as the figure 4 shows in three dimentional illustration, the combination of two inversely rotating mechanisms of the type of figure 2 results into the change of the revolution of a shaft to a harmonic reciprocation (in the case of constant angular velocity) .

The tuning (regulation) of the cranks Kl and K2 can be realized by using, among others, the following modes:

-By using beveled gears that rotates with the cranks fixed on them and tuned with one or more beveled gears (just like the classical defferential of the cars).

-By using gears. The two main gears which are connected with the crankshafts and are tuned at inverse rotation with the use of a pair of gears.

A special case is illustrated in the figures 5 and 6 . Here exists a cooperation of four beveled gears of the same size and shape. Actually they are four mechanisms similar to that of the figure 2 syncronizing each other, two on the ZZ' axis (as illustrated in figures 3 and 4) and two on the XX' axis. The gears G1,G2,G3 and 54 have four cranks and with four connecting rods (C1,C2,C3 and C4) drive the unique piston P1-PA-P2 which is permorming a harmonic reciprocation. There are still notches (on the basis) and projections (T1,T2,T3 and T4) on the rods for the elimination of the points of lndeflniteness.

In the figures 7 and 8 the gear Gl have a pitch diameter Dl, the gear G2 have pitch diameter D2= .5*D1 (half of Dl), and the gear G3 has pitch diameter D3. The gear Gl is kept immovable. The rod BC is fixed on the gear G2 and BC=KB. Finally the gear G3 is meshed with both Gl and G2. As the triangular KAB is rotating around K - with constant angular velocity ω (figure 7) - the gear G3 because it is meshed with Gl, rotates with ω3 at the direction shown in the figure and of magnitude ω3 -= ω * Dl / D3 . Since the G2 is meshed with the

G3, the gear G2, and with it the rod BC, rotates with ω2 angular velocity at the direction shown in the figure and of magnitude ω2 = ω3* (D3 / D2) = ω * (Dl / D3) * (D3 / D2) so finally ω2 = 2 * ω. So we have a movement of the rod BC

with 2 * ω and at a direction shown in the figures 7 and 8.

Now let it be Bl the new position of the B point, Cl the new position of the C point and C the section of the line B1C1 and the axis YY' (figure 8) as the mechanism of figure 7 rotates (The rest mechanism of figure 7 is not shown

-for simplicity- in the figure 8).

In figure B is ^Λ B1KC'= φ+ ^Λ BKC and ^Λ KB1C = ^Λ KBC-2*φ and BlKC'+'KBlC'+ ^Λ BlC'K=π ===>~B1C' K=π-φ- ^Λ BKC-^KBC+2*φ=

=π+φ-π+ ^Λ BCK-=φ+ ^N BKC*='BlKC' (the symbolism ^Λ B1KC means the angle of the lines KB1 and KC )

It means that the triangular KB1C is isosceles. Thus KB1=B1C =B1C1 which means that the end C of the rod BC can move only along the YY' axis.

Still is KC=2*KB*cαsC-BKC)===> KC=2*KB*cαs(ω * t + -fo) which means that the distance of the end C from the origin of the axis K is a harmonic function of the time.

In figure 9 PI and P2 are the pitch circles of the gears Gl (external toothed) and G2 (internal toothed) and Dl , D2 are their diameters respectivelly. Let be D2=2*D1 and

KA=D2 / 4. Let also that G2 is immovable. If the branch KA turns, with constant angular velocity ω, around the end K and on the other end A is fixed the center of the Gl, then any point of the pitch circle of Gl is performing a harmonic reciprocation along a certain diameter of P2. The proving is the same as that already done for the mechanism of the figures 7 and 8. Namely, the angular velocity of AB with regard to KA is twice the angular velocity of KA around the K and KA=AB. The rest indentical ... What has been prooved, so far, is the possibility of changing a rotation into a harmonic reciprocation. The previous described mechanisms are, also, slider free, since the reciprocation is independent from the presense of any si ider. "How the names correspond"

Figure 10 illustrates a gradual transition from the conventional reciprocating engines M and Ml to a certain of the suggested harmonic engines M5 in order to be shown the intendification of the functions of the respective components and consequently to justify their similar names. So:

M Ml M2 M3 M4 M5

The engine M uses a slider: the "piston skirt - cylinder wall". It has a stroke S=2*r and the length of the connecting rod is usually between AE=1.5#S and AE=2.5*S.

The engine Ml uses a seperate slider instead of the "piston-cylinder wall". This arrangement is used in big Diesel and in steam engines. The stroke is also S=2*r.

The engine M2 is similar to Ml but has a smaller connecting rod. It is still the stroke: S=2#r.

The engine M3 is similar to Ml but the length of the connecting rod is A3E3=r=K3A3. Now the stroke is S=4*r. It is obvious that into M3, Ml and M the parts correspond functionally .

Thus K3A3 is the crankshaft , A3E3 is the connecting rod, P3 is the piston.

The engine M4 is the M3 but has A4K4=r/2=A4E4, in order to decrease the stroke to S=2#r. Like the engine M3, in the engine M4 we have K4A4 as crankshaft, A4E4 as the connecting rod and P3 as piston.

Finally the engine M5 is a suggested form of harmonic engine. Is merely the engine M4 where a pair of internal and external meshed gears substitutes the slider. The relation between the parts of M5 and M is obvious now. That is K5A5 is regard as the crankshaft, A5E5 as connecting rod, P5 as the piston e.t.c. MODES FOR CARRYING OUT THE INVENTION

The engine illustrated in section view in figure 11 and in exploded form in figure 12 is an internal combustion four-stroke cycle, two cylinder in line engine with 360 degrees crankshaft. It is fully balanced from inertia forces and inertia torques caused by its kinematic mechanism and is even firing. It is harmonic (that is : for constant angular velocity of the shaft, the motion of the pistons is a harmonic motion). It has slider free motion of its connecting rod mechanisms. In more detail (figures 11 and 12):

1 : Connecting rod mechanism. Consists of

1A and IB : balance weights on the connecting rod 1C : gear on the connecting rod. It meshes with the immovable internal gear 6C to produce harmonic reciprocation.

ID and IE :upper pins of the connecting rod. They operate actually as piston pins. IF and 1G : lower pins of connecting rod mechanism 1H and II :oιl passages for the lubrication of the piston pin beaππs.

2 : Crankshaft mechanism. Consists of: 2A : balance weight on the crankshaft 2 2B :geaπnα on the crankshaft

2C :oιl passages for lubrication 2D : bearing for the lower pin IF of the connecting rod mechanism.

3 : Crankshaft mechanism. Consists of: 3A : balance weight on the crankshaft 3 3B :gearιng on the crankshaft 3C :oιl passages for lubrication

3D :beaπng for the lower pin 1G of the connecting rod mechanism.

4 : Piston

4A :pιston rings (compression and oil) 4B :pιston head

4C :pιston pin bearing

: Piston

5A :piston rings

5B :piston head

5C :piston pin bearing

: cylinder block and engine cover.

6A and 6B: bearings for the crankshaf s 2 and 3

60 : immovable internal gear

6D :cylinder wall

6E :cooling liquid

6F and 6G: bearings for the shaft 7

6H :oil pan

7 : shaft for the tuning (and for torque transmission) of the crankshafts 2 and 3

7A :gear meshed with 2B of crankshaft 2

7B :gear meshed with 3B of crankshaft 3

70 and 7D: auxiliary shafts (they can be used to drive oil pump, water pump e.t.c.) Remarks a. The pitch diameter of the internal gear 6C is equal to the stroke of the piston. b. The pitch diameter of the gear 1C is half of that of internal gear 6C. c. Pins ID and IE are on the same line (axis). d. Pins IF and 1G are on the same line (axis). e. Distance between the axis of IF and the axis of ID is equal to one quarter of the stroke of the piston.

"Operation description"

Rotating the shaft 2 with constant angular velocity, the shaft 3 is also rotating with the same angular velocity (due to the mechanism 7 and the meshed gears 7A and 2B and the meshed gears 7B and 3B) . The connecting rod mechanism is forced (through the lower pins IF and 1G and the corresponding bearings 2D and 3D on the shafts 2 and 3) to follow the motion of the shafts. Due to the meshed gears 1C, of the connecting rod mechanism, and 6C (immovable on the block) the resulting motion for the axis of the piston pins ID and IE of the connecting rod mechanism is a harmonic motion (this was explained in the paragraph for the mechanisms) . So the pistons 4 and 5 , connected with their bearing 4C and 5C on the piston pins ID and IE of the connecting rod mechanism, are forced to reciprocate harmonical ly in their cylinders. The rest is the same as in the conventional engine.

The systems not shown in the figures (i.e. cylinder head, fuel system, ignition system, exhaust system, lubrication and cooling systems e.t.c.) are similar in operation and shape to those used by a conventional internal combustion engine with two in line cylinders and 360 degrees crankshaft.

The flywheel can be fixed on the shaft 2 and then the shaft 3 is used to drive the camshafts and the auxiliary devices (i.e. cooling fan, alternator e.t.c).

For the lubrication of the kinematic mechanism: Oil with the appropriate pressure is fed to the constant bearings

6A and 6B . Through the holes 20 and 3C the oil is passed to the bearings of the connecting rod pins IF and 1G. Finally

through the holes 1H and II the oil lubricates the piston pin bearings 4C and 5C. The lubrication of the piston skirt, piston rings and cylinder walls is achieved by the oil thrown-off from the bearings 6A, 6B, 2D, 3D, 4C, 5C. In the exploded form of the engine in figure 12, there exist also the piece 44 not yet used. This is a double piston with one common bearing for single piston pin. If the mechanism 7 (for the tuning of the 2 and 3 crankshafts) changes place sidewise, the pistons 4 and 5 be replaced with them of the form of the 44 double piston and another pair of cylinders be added (to cooperate with the lower part of the double pistons) then the engine becomes a flat four cylinder harmonic engine, while the number of moving parts remains the same, as well as the number of the bearings (form of block similar to that of the engine in figure 13) "Balancing the engine"

For constant angular velocity of the shaft 2 the pistons 4 and 5 reciprocate harmonically. The forces from the pins ID and IE, of the connecting rod mechanism, to the pistons 4 and 5 cause this harmonic motion (we refer here only to inertia forces and torques so we ignore any force or torque caused by gasses pressure). Those forces are of the form : F = m * ( S / 2 ) * ω * ω * cos(ω * t + fo) where: m : mass of the assembly: piston, piston rings and piston pin bearing S : the stroke of the piston ω : the angular velocity of the shafts 2 and 3 fo: the initial angle (for t=0)

If the "piston, piston rings and piston pin bearing" assembly is replaced with an equal mass properly placed on the axis of the piston pin, this mass loads the connecting rod mechanism with exactly the same force F (as piston pin axis moves harmonically). So, for the rest of the system either a piston or an equal mass on the axis of the piston pin imply exactly the same inertia loads. Now what must be noticed is that the motion of the connecting rod mechanism (and the equivalent masses of piston assemblies on the piston pins of the connecting rod as was described just above) is a combined motion : it is a rotation around the axis of the lower pins IF and 1G of the connecting rod (with constant angular velocity 2#ω) and another rotation - together with the crankshafts 2 and 3 - with constant angular velocity ω around the axis of the two shafts 2 and 3 of the engine. Two balance weights 1A and IB are enough for the full balancing of the first motion of the "connecting rod - equivalent masses" assembly. With two more balance weights 2A and 3A on the crankshafts the whole kinematic mechanism is completely balanced.

Practically, for the balancing of the engine , the following steps are enough : initially the "piston, piston rings and piston pin bearing" assemblies are substituted with ring shape masses equal to the mass of the assembly of the piston-piston rings-piston pin bearing and located around the corresponding piston pin ID and IE. Then the connecting rod

mechanism (together with the equivalent ring shape masses) is balanced by the two balance weights 1A and IB with regard to the rotation around the axis of the connecting rod pins IF and IG. Finally the whole assembly of the crankshafts 2 and 3, the connecting rod mechanism 1 and the equivalent ring shape masses (on the pins ID and IE of the connecting rod) can be completely balanced, with regard to the rotation around the common axis of the shafts 2 and 3, by means of two balance weights 2A and 3A on the crankshafts 2 and 3. That is all. Using the chosen balance weights 1A, IB, 2A and 3A the two cylinder engine is completely balanced. On the basis of the engine is not transmitted either inertia forces or inertia torques - caused by the kinematic mechanism of the engine - when the engine is running with constant angular velocity.

The engine illustrated in section view in the figures 13, 14 and 15 is an internal combustion four—stroke, four cylinder flat (boxer) engine. Also it is a harmonic engine with slider free motion of its connecting rod mechanisms. This engine with properly selected balance weights is a completely balanced engine.

In more detail (figures 13):

1 : Connecting rod mechanism. Consists of: 1A and IB: piston pins of the connecting rod

1C and ID: balance weights of the connecting rod IE and IF: lower pins of the connecting rod 16 : gear of the connecting rod. It meshes with the immovable internal gear 3G to produce harmonic reciprocation.

2 : Crankshaft mechanism. Consists of:

2A and 2B: balance weights of the crankshaft 20 and 2D: main crankshaft journals

2E and 2F: bearings - on the crankshaft - for the lower pins IE and IF of the connecting rod mechanism 2G: gear on the' crankshaft for the transmission of the rotary motion (and torque) of the crankshaft to an external shaft 3 : Cylinder block of the engine:

3A and 3B: bearings for the crankshaft main journals

2C and 2D 3C and 3D: the two upper cylinders of the engine 3E, 3F and 3H: cooling liquid 3G : immovable (with respect to the block) internal gear 4 : Piston (it is a double piston, it has two piston heads 4B and 4D that are connected with the same piston pin IB) 4A: piston 4 bearing

4B: piston 4 head (upper head) 4C: piston 4 compression and oil rings 4D: piston 4 head (lower head)

4E: piston 4 compression and oil rings (lower) 5 : Piston (similar to the piston 4)

6 : external shaft

6A and 6C:parts of the external shaft 6 6B: gear of the external shaft 6 meshed with the gear 2G of the crankshaft. Remarks a. The pitch diameter of the 3G internal gear is equal to the stroke of the pistons b. The pitch diameter of the IG gear of the connecting rod is half the stroke of the pistons. This gear is meshed with 3G internal gear c The piston pins 1A and IB are on the same axis d. The lower pins IE and IF of the connecting rod are on the same axis too f. Distance between the axis of piston pin 1A and the axis of the pin IE of the connecting rod is one quarter of the stroke of the pistons.

The figures 14 and 15 are section views of an engine similar to that of figure 13. The figure 14 shows the form of the double piston 5, of the balance weights 2A and 10 , the section (in another plane) of the cylinder head and the teeth belt 7 with which the shaft 6 drives the camshaft on the cylinder head. In the figure 14 the crankshaft is 45 degrees after top dead center, so the piston 5 has performed a part of its stroke. The figure 15 is another section of a similar engine. Here the crankshaft is rotated 90 degrees after top dead center. In this figure the bearings 3H, 31, 3K and 3L for the housing of the external shaft 6 are shown. The side of the shaft 6 which drives the flywheel is stronger than the side which drives the camshafts and the auxiliary devices.

"Operation description" Rotating the external shaft 6 with constant angular velocity, the crankshaft 2 (due to the meshed gears 2G and

6B) is forced to rotate with constant angular velocity. The connecting rod mechanism is forced , due to the lower pins IE and IF -that rotate into the crankshaft bearings 2E and 2F- to follow the rotation of the crankshaft. Now the meshing of the gear IG of the connecting rod with the immovable gear 3G modifies the motion of the connecting rod so that the axis of the piston pins 1A and IB of the connecting rod mechanism is moving harmonically. Finally the pistons 4 and 5 are forced (by the piston pins 1A and IB) to reciprocate harmonically inside their corresponding cylinders. The rest operation is similar to that of the conventional engines.

The systems not shown in the figures are similar in operation and shape to those of the well known conventional engine.

For the balancing of this engine , the same process - as described previously for the engine illustrated in figures 11 and 12 - is followed. It is a step by step balancing method as follows: Initially the connecting rod and piston assemblies are balanced (with respect to the rotation around the axis of the lower pins IE and IF of the connecting rod mechanism) by the counterweights 1C and ID . Then the complete kinematic mechanism is balanced (with respect to the rotation around the axis of the main journals 2C and 2D of the crankshaft) by the balance weights 2A and 2B on the crankshaft. The result is a completly balanced engine.

If, instead of the double pistons 4 and 5, two single pistons (like those described in the previous two cylinder in line engine) are used , then a two in line four-stroke harmonic engine results. It is also slider free with regard to the motion of the connecting rods. And of course a similar balancing can be achieved.

If two four cylinder flat engines, similar to the above described, with suitable difference in timing (typically 90 degrees) share the same external shaft (external shaft 6 for the engine of figure 13, 14 and 15) then an eight cylinder engine completely balanced (with regard to inertia forces and inertia torques) and even firing is accomplished. In the figure 16 are shown the main moving parts of this engine as well as its block in three dimensional views. This is the best mode for carrying out the invention especially for big displacement-high performance engines for racing cars.

The figures 17 and IB are section views of a two stroke cycle, two cylinder flat (boxer), internal combustion engine of the harmonic type. The connecting rod mechanism has slider free motion. It has also the behind the piston chamber sealed from the crankcase. This space is used for the scavenging. Properly selected balance weights for the connecting rod and for the crankshaft give the engine a full balance as far as the inertia forces and torques are concerned.

Here is:

1. Crankshaft 1A and IB: bearings on the crankshaft 1, for the lower pins 2A and 2F of the connecting rod mechanism 1C and ID: balance weights on the crankshaft

2. Connecting rod mechanism 2A and 2F: lower pins of the connecting rod mechanism. 2C: Gear on the connecting rod meshed with the immovable gear 5A 2B and 2D: balance weights on the connecting rod 2E: Piston pin, on the connecting rod mechanism

3. and 4. roller bearings for the housing of the crankshaft 1 on the basis 5A of the engine 5. Basis of the crankcase

5A: immovable internal gear 6. Piston. It is a double piston with:

6A: bearing of the piston pin 2E 6B: piston head (upper piston head) 6C: piston rings (upper piston rings) 6D: piston skirt (it is used to open and close the output port 7)

7. Output port

8. Input port and transfer port 8A: one way valve (check valve)

9. Cylinder wall 9A: cooling liquid

9B: engine cover

9C: spark plung 10. Separation surface between the space behind the piston and the crankcase 10A: hole on the 10 through which the stem of the piston is reciprocating.

10B: the contact contour between the separation surface 10 and the cylinder wall 9 Remarks a. The pitch diameter of the immovable internal gear 5A is equal to the stroke of the piston b. The pitch diameter of the gear 2C of the connecting rod mechanism is half of the stroke of the piston c The distance between the axis of piston pin 2E and the axis of the lower pin 2A is one quarter of the stroke of the engine

"Operation description"

As the crankshaft 1 turns with constant angular velocity, the connecting rod mechanism is forced to follow the rotation of the crankshaft due to the cooperation of the bearings 1A and IB, on the crankshaft, with the corresponding pins 2A and 2F of the connecting rod mechanism. Now due to the meshed gears 20, of the connecting rod, and 5A, immovable on the block, the motion of the connecting rod is so modified that the motion of the axis of the piston pin 2E of the connecting rod is a harmonic reciprocation. The piston, joined with the connecting rod mechanism at the piston pin 2E, is also forced to reciprocate harmonically in the cyl lnder.

The separation surface 10 is a shell shape part (or combination of parts) that (as shown in the figures 17 and IB) is fixed on the cylinder wall and is in sealing touch with the piston stem. It is immovable with regard to the block. The piston stem reciprocates inside the hole 10A of the 10 separation surface but is kept always in touch with it (for instance by the use of suitable rings). So the surface 10 insures the sealing between the crankcase and the behind the piston space.

As the piston moves up, due to the vacuum in the space behind the piston, fresh air or mixture, through the one way valve 8A in the intake port, enters in the space behind the piston. After the ignition the piston is moving down. The pressure in the space behind the piston is increased. The one way valve 8A closes and the trapped fresh air or mixture is compressed. As the piston continous the downward motion, lmtialy the output port is revealed. The pressure in the combustion chamber drops quickly. Then the input port (that operates and as transfer port) is revealed. The compressed fresh air or mixture starts the scavenging process. After the bottom dead center the piston starts moving upwards. As the pressure is decreased, in the space behind the piston, the one way valve 8A opens again. Fresh air or mixture enters.... And so on.

An important advantage is that by changing —or controlling- the "dead" volume of the space behind the piston (that is the volume of the trapped air or a i t—Fuel mixture, behind the piston, the moment that the transfer port is

revealed by the piston) the initial scavenging pressure is signi icantly changed. This is the principle for controlled scavenging system. It can increase signi icantly the domain of rotating speeds where the two-stroke engine can breath (and so work) effectively. A way to change this "dead" volume is by changing the position -in the intake pipe- where the one way valve 8A is located or by using auxiliary external chambers with volume added (and removed when neccesary) to the behind the piston space. The balancing of the engine can again be complete.

The main balance weights are the ID and 2D. The other two weights are used because the motion of the main balance weights and the mass they counterbalance (that is mainly the piston mass) are not on the same plane. For the rest, the balancing process is simillar with that described previously.

The lubrication of the crankcase, due to the separation surface, can be independent from the lubrication of the piston rings and cylinder wall. So the quality of the crankcase lubrication is as in the four-stroke engines. Modified form of harmonic engines that use the same kinematic mechanism as that described here are : a. One cylinder two-stroke internal combustion engine. This engine is exactly the previous one but with only the one cylinder and with the double piston being replaced by a single one. b. Four—stroke, two cylinder flat internal combustion Harmonic engine. The necessary modifacatiαns are obvious. c. Four-stroke, one cylinder internal combustion harmonic engine, full balanced. In four-stroke or in two-stroke cycle engines using a separation mechanism (surface) like the above described mechanism 10, of the figures 17 and 18, and properly shaped piston's stem, the crankcase can be sealed from the cylinder wall. The separation surface is: fixed on the lower part of the cylinder wall and in sealed contact with the piston stem (i.e. by proper rings). This method of separation of the crankcase from the cylinder wall can be used especially in adiabatic engines. The advantage it offers is the ability for complete absence of oil (indispensable for the lubrication of the moving parts into the crankcase) from the hot cylinder wal Is.

In the figures 19 and 20 is shown, in section views, a single cylinder, four-stroke internal combustion engine. It is also a harmonic engine with slider free motion of its connecting rod mechanism. Also it is an engine with kinematic mechanism similar to that described in figure 7. In detail (figures 19 and 20) 1 and 2. Crankshaft mechanisms with: 1A and 2A: gears meshed with the gear 3A and 3B of the shaft 3, for tuning the rotation of the two crankshafts 1 and 2, as well as for the transmission of torque between the crankshafts.

1C and 2C: balance weights on the crankshafts 1 and 2 respectively.

IB and 2B: bearings on the crankshaft mechanisms 1

and 2 for the lower pins 4C and 4D of the connecting rod mechanism 4.

3. Auxiliary shaft with:

3A and 3B: gears meshed with the 1A and 2A gears of the crankshafts 1 and 2 correspondingly

4. Connecting rod mechanism with:

4A and 4B: gears of the connecting rod mechanism 4C and 4D: lower pins of the connecting rod, on the same axis. 4E and 4F: balance weights on the connecting rod.

4G: piston pin of the connecting rod mechanism.

5. Piston with:

5A: piston pin bearing 5B: piston ste 5C: piston head

5D: pressure and oil rings on the piston 5

6. Crankcase and engine cover with:

6A and 6B: immovable gears. They have pitch diameter twice as that of the gears 4A and 4B on the connecting rod mechanism. They are not directly meshed with the 4A and 4B gears. 7 and 8. A couple of gears, meshed with both: 6B immovable gear (with refference to the crankcase) and 4B gear of the connecting rod mechanism. The gears 7 and 8 are -free to rotate around axles constantly fixed on the crankshaft 1. By means of gears 7 and 8, the 4B and 6B gears can cooperate. Another similar couple of gears is used on the other crankshaft 2 to cooperate with both the 4A gear of the connecting rod and the immovable gear 6A

9. Cylinder

"Operation description"

As the crankshaft 1 turns with constant angular velocity, the crankshaft 2 (due to the 3 mechanism and the meshed gears) turns with the same angular velocity. The connecting rod mechanism 4 is forced to follow the rotary motion of the crankshafts 1 and 2 (due to the cooperation of the bearings IB and 2B of the crankshafts with the lower pins

4D and 4C of the connecting rod mechanism). Now the gears of the connecting rod mechanism in cooperation with the immovable gears (indirect cooperation by means of the intermediate couples of gears like the 7 and 8) modifies the motion of the connecting rod so that the movement of the axis of the piston pin becomes a harmonic reciprocation. So the piston reciprocates harmonically into the cylinder. The rest is similar with the well known conventional engine.

The balancing process is a step by step balancing similar to that described for the previous engines. The result, by correct selection of the balance weights, is a completely balanced one cylinder reciprocating engine, with refference to the inertia forces and inertia torques caused by the kinematic mechanism.

This version of the harmonic engine is exceptionally competent for very long stroke engines. Such engines, whenever the problem of the volumetric efficiency can be solved (for instance, by using through-scavenging poppet

exhaust valves) can be proved extremely efficient thermodynamical ly and clear with regard to emissions. Will be also significantly light and short in comparison with the equivalent conventional engines.

INDUSTRIAL APPLICABILITY The invention can be used, at least, where a conventional reciprocating heat engine is used now.

The foregoing description taken together with the appended claims constitute a disclosure such as to enable a person skilled in the reciprocating heat engines art and having the benefit of the teachings contained therein to make and use the invention. Furthermore structures herein discribed meet the objects of the invention and generally constitute a meritorious advance in the art unobvious to such a person not heaving the benefit of these teachings.

Obviously, many modifications and variations of the present invention are possible in the light of the above teachings, and, it is therefor understood that within the scope of the disclosed inventive concept, the invention may be practised otherwise than as specifically described. REFERENCES

1. Colin R. Ferguson

"Internal Combustion Engines-Applied Ther αsciences"

2. Charles Fayette Taylor

"The internal combustion engine in theory and practice"

3. William H. Crouse "Automotive engine"

4. Charles Kittel "Mechanics-Berkeley Physics"

5. Artobolevsky Ivan "Mechanisms in modern engineering"