[0001] iln the field of mechanical engineering, internal combustion engines of pistons (IPC F02B) have very low energy efficiency and considering the number of such machines in operation on the planet, a huge amount of fuel is wasted in the form of pollutants. Since its invention, these engines had no significant mechanical changes to improve its performance, which occurred almost exclusively by the application of electronic components (sensors and injection). Such a restriction harmed the evolution of Diesel cycle engines and the 2-stroke engines, even still enshrined in the advantageous aspects of performance, power consumption and maintenance, are seen as villains mainly because they are more polluting.

[0002] All existing piston engines have in common the transformation of rectilinear and harmonic motion of the piston directly in continuous circular movement performed by the crankshaft. This transformation is partly responsible for the low efficiency of the system due to lack of agreement of the reaction phases of the piston and crankshaft movements. This invention aims to reduce significantly this disagreement, creating an intermediate movement.

[0003] To achieve this intermediate movement, the conventional connecting rod is transformed in the "command rod" which differs from the first by the tip that connects to the crankshaft. At this extremity the "command rod" is formed by a closed contour gear with internal teeth, rigidly attached to your arm, formed by the union of conveniently calculated tangential arcs and straights in order to make the most the position of the piston during its course and, thus better meeting the explosion phase, scavenging, admission (including supercharge) and compression. For the application of "command rod", there is the need of the crankshaft exclusion to be replaced by a major axis that will make your circular motion inside the "command rod gear" thanks to a belt of printed teeth at this axis and a pair of swivel clamps (or a double swivel clamp), which fastened to the shaft, embrace the external surface of the "command rod gear" through the swivel clamps pins.

[0004] This invention can be applied to any type of internal combustion engine pistons, in any architecture (in-line, in-V, horizontally opposed, radial, axial, tangential and others). It will allow a large jump in performance, especially in 2-strokes Diesel cycle engines, putting them ahead of the others.

[0005] Thus, in order to highlight the benefits achieved in this type of engine with the application of the object of this patent within the market reality, all studies for the preparation of the invention were referenced in a motor with the following characteristics: 3 cylinders of 474cc each, diesel cycle, 2- strokes, one-way inlet and exhaust flow with openings reformatted air intake, turbo 2.3 bar, combustion control and direct fuel injection (CCID), exhaust valve with double outlet (by-pass) for use the high pressure for feed the turbine, intelligent electronic control (VVT-iE) and cooling system with recirculation, compression ratio 19.5:1, stroke of 95.5mm and 79.5mm piston bore (S/B 1:20 or B/S 0.83), 70 kW (90 HP) and 230 Nm (1500 to 2500 rpm), the connecting rod axis length of 173mm, the crankshaft axis diameter of 47.75mm and 26mm diameter piston pin.

[0006] Assuming an equivalence of materials and internal forces, the inner main shaft to replace the crankshaft are dimensioned here with the same diameter of the latter (47.75mm), and each swivel clamp pin is dimensioned here with the same diameter of the pin that connects the connecting rod to the piston (26mm). Regarding the "command rod gear", were designed in three profiles for comparison: a symmetrical profile whose arcs have a diameter equal to the piston stroke (95,5mm), another asymmetric profile following the same criteria as above, and an asymmetric profile with reduced arcs radius adopting the diameter of 74.32mm, the lowest enough to the other segments meet all stages of the process.

[0007] For explosion stage, while the piston moves from TDC (top dead center) to the position where the explosive force generating work is relevant to the system (about 60% of the stroke), it is important that the force component that presses the piston against the cylinder wall be as small as possible to reduce wear of the surfaces, so the profile section of "command rod" in this stage should be a straight line aligned with the central imaginary axis of the piston movement and tangential to the inner main shaft to ensure the highest possible torque for the entire course. The symmetrical profile has the disadvantage of not allowing the alignment of the imaginary axis of the rod with the straight segment on the explosion phase of the gear.

[0008] In the phase of scavenging and intake air in the cylinder, it is best that the piston be parked in BDC (bottom dead center) allowing maximum opening of the air intake ports, the maximum surface cylinder area for cooling and cleaning, and the maximum volume air intake. To achieve this result, the profile segment should be a convex arc of radius equal to the length of the connecting "command rod" axis. This section is followed by a segment of concave arc calculated in order to obtain the best use of forced air intake (supercharge) taking into account the reduction of the cylinder volume, the differential pressure and the closing of the air intakes advantage including shock air with the fast and early closing of the exhaust valve.

[0009] The compression of the air or mixture in the cylinder should occur more slowly and evenly to avoid pressure losses and faster immediately before TDC to prevent heat loss. Furthermore, the start of combustion should occur as close as possible to the point where the compression ratio is optimal. These performances can be achieved with the creation of a short arc portions near TDC with diameters tending to the internal diameter of the main shaft within the limits of variation of the crank angular speed.

[0010] The results of this combination are: better scavenging, better exchange of heat and gases in the cylinder by reducing pumping losses, better breathing with small ports, more "dwell", smaller angles of the rod during power stroke, significant reduction of the piston speed reducing wear of major thrust surface, better control of the specific heat ratio, small moment variations increasing the useful torque and, thus, higher performance. In addition, the invention enables all the aforementioned improvements can be achieved without significant changes in the motor structure.

[0011] For a better understanding of the invention and its advantages, is made then a detailed description of the invention using previously described reference engine and the accompanying figures.

[0012] [Fig.l] shows a sequence of projections of "command rod" and the piston 2 in the cylinder 1 in four consecutive positions: position A, relative to the TDC, position B, relative to the beginning of the explosion phase with significant piston 2 response (about 15% of the course), position C, relative to the end of the explosion phase in which the piston 2 has a reduced response and it is desired to take advantage of the inertia of the exhaust gases (approximately 60% of the course) and position D, where the piston 2 is parked at BDC within the scavenging and admission phase. The "command rod gear" with internal teeth 6 of this figure is a symmetrical profile.

[0013] [Fig.2] shows the same sequence of projections but to a gear 6 with an asymmetric profile (more appropriate for each phase) formed with concave arcs of equals radius.

[0014] [Fig.3] also shows the same sequence of projections but to a gear 6 with an asymmetric profile with concave arcs of varying and reduced radius (even more suitable for each studied phase).

[0015] [Fig.4] is a realistic drawing of the internal reference motor system (pistons, "command rods" internal short shafts and bevel gear transmission) in the axial configuration (architecture).

[0016] [Fig.5] shows the same way with the same setting the in-line architecture where the internal long main shaft is common to all the "command rods".

[0017] [Fig.6] shows similarly the same set in a tangential configuration (more compact than the radial one).

[0018] At the figures 1, 2 and 3 has been considered more important to represent the imaginary axis of the "command rod arm" 5 then its projection, because the invention described herein is independent of the reinforcing profile and other profiles in the vicinity of the part that will be dimensioned for production in function of internal forces for each power, size and motor arrangement. The imaginary axis 5 rises from the center pin 3 that locks the "command rod" in the piston and shows the rod angle relative to the piston 2 movement. The internal main shaft 7 can be long and common to all pistons to meet the in-line (fig. 5), the opposite horizontal or in-V architecture, or attached to a short single piston to meet the axial (Fig. 4), radial or tangential (fig. 6) architecture. In the latter case, must have a short-axis bevel gear transmission to combine with the other pistons on a common shaft.

[0019] For the "command rod gear" 6 does not miss contact with the internal main shaft 7, is used a double swivel clamp 9, or a pair of swivel clamps, attached (but rotate freely) to the internal main shaft, pressing the gear against the internal main shaft by the swivel clamps rotating pins 8 that run on the external face of the gear.

[0020] As an immediate result of the elaboration of profiles here adopted, it was observed that their perimeters are approximately three times greater (2.68x, 2.89x and 3.02x, respectively) than the perimeter of the circle created by the reference engine crankshaft revolution, increasing the number of rotations of the internal main shaft compared to the crankshaft, which means more power with less speed. However, this increase has as major disadvantage mass moment of inertia that increase internal forces and vibrations but can be minimized by increasing the length of the pitman arm.

[0021] The radius of the arcs that form the profiles also has significant influence on the vibrations and internal forces, the profiles of [Fig.l] and [Fig.2] (diameters greater than or equal to the distance of piston stroke) reduces the angular velocity of the rod and thus reduces the efforts about 50%. Since the profile of [Fig.3] (arcs reduced in diameter), the angular velocity increases, thereby increasing efforts to about 40%

[0022] In the power stroke phase we have two great advantages, a considerable increase in torque and the reduction of the normal force that the cylinder wall apply on the piston, so we have more power, less friction, heat and wear. The [Tablel] below compares some reference engine indexes with the application of the studied profiles. The average arm and the percentage of the contact force are applied to the piston force generated by the explosion. The internal main shaft is half the diameter of the circumference formed by the revolution of the crankshaft and about three times (3x) faster, so the transmission of efforts to a second axis, with rotation speed equals the reference engine crankshaft speed, results in higher and longer acting torques. In the first 15mm piston displacement from the TDC, the average reference engine torque using the "command rod" is about 40% higher compared to the conventional connecting rod. Between 15mm and 57mm piston displacement (best explosion effect), the average torque of the reference engine using the "command rod" is about 90% higher.

[0023] [Tablel]

[0024] In the scavenging and admission phases the great advantage achieved is the complete stop of the piston at BDC while the shaft completes a certain number of rotations. This allows a complete opening (100%) of air intake ports 4 during much longer time compared to the conventional system whose intake ports reach the 100% open only for an instant, keeping an average opening of 60% only. For the profile of fig. 3 shown in [Table2] below, the air intake ports 4 remain 100% opened for 36° of rotation of the reference conventional crankshaft. Using the "command rod" the intake ports size could be reduced at least 40% of its current size, still having a higher efficiency.

[0025] [Table2]

[0026] In the compression phase of the air or mixture in the cylinder, the start of combustion should occur as close to the point where the compression ratio is optimal. This is most easily achieved in the Otto cycle because the start of combustion is determined by the ignition of the candle, but the Diesel cycle, the start of combustion depends on the start of fuel injection into the cylinder. Considering that the maximum compression occurs when the piston is at its TDC, there is a time between the fuel injection and the start of combustion, and another time is demanded for the start of combustion results in explosive force, it is for the best that the piston be as close as possible to the TDC during these events. The reduction of the piston velocity using the "command rod" allows the advance of ignition or injection with a reduction of about 60% of the distance of the piston to TDC.

[0027] Another advantage achieved is that the "command rod" easily adapts to different engine architectures. [Fig.4] shows the axial modern architecture which gives a cylindrical conformation to the engine, ideal for aircrafts. In [Fig.5] we have the traditional in-line architecture, the most widely used, and [Fig.6] shows a tangential architecture (most compact radial variation) leaving the engine disc-shaped conformation.

8] It is expected with this invention, a significant improvement in the efficiency of internal combustion engines with increased power, reduced fuel consumption and pollutant emissions. The diameters of the internal main shaft and the radius of the concave arcs "command rod gear" tend to be reduced over time, bringing even greater efficiency. This invention greatly benefits Diesel cycle 2- strokes engines that tends to work with higher rates of "stroke/bore".