WO2008092218A1

WO2008092218A1 - An internal combustion engine with extended stroke

Info

Publication number: WO2008092218A1
Application number: PCT/BR2008/000003
Authority: WO
Inventors: Cássio MOREIRA MACHADO
Original assignee: Moreira Machado Cassio
Priority date: 2007-02-02
Filing date: 2008-01-03
Publication date: 2008-08-07
Also published as: BRPI0701061A

Abstract

The invention relates to a 4-stroke internal combustion engine with one or two of these strokes, expansion and intake, extended by employing rotating-piston (101) positive-displacement rotary flow machines (100) individually coupled to each of its cylinders (2), with cyclic motions adequately synchronized with the strokes of each reciprocating piston (1) of the engine. The positive-displacement rotary flow machines (100) usable in the concept of this invention have preferably only one rotating-piston (101 ) per active rotor (102). As a result of their shapes and constructive arrangements, they require or generate pulsating flow of the gases with which they work, a characteristic that is now an important advantage for the synchronized coupling with the engine cylinder (2). By controlled expansion, in a synchronized manner, of the gases discharged from each cylinder (2), a significant portion of the energy contained in them is used to generate additional torque and power on the engine crankshaft (5). By controlled pre-compression, in a synchronized manner, of the air or air/fuel mixture that will be taken into the cylinder (2), it is possible to charge it always with the same amount of air, independently of the rotation velocity (V) of the engine crankshaft (5), with less response delay for acceleration of that rotation. Alternatively, the expansion and intake strokes of the cylinder (2) of a conventional engine can be extended by employing auxiliary cylinders (402) coupled to it in an individual and synchronized manner, instead of rotating-piston (101 ) positive-displacement rotary flow machines (100).

Description

Specification of the patent of invention for: "AN INTERNAL COMBUSTION ENGINE WITH EXTENDED STROKE".

The present patent application relates to a 4-stroke internal combustion engine with one or two of theses strokes, expansion and intake, being extended by employing rotating-piston positive-displacement rotary flow machines individually coupled to each cylinder, with motions adequately synchronized with the strokes of each reciprocating piston of the engine. DESCRIPTION OF THE PRIOR ART

Being widely used for propulsion of vehicles or for stationary drive of pumps, generators, compressors and other machines, internal combustion engines use the energy from burning liquid or gaseous fuels to move their reciprocating pistons. They change the linear alternative motion of

, the pistons into rotating motion of the transmission shaft through the ingenuous use of rods and crankshafts. Although these engines are extremely reliable and versatile, they have low energy efficiency. According to Heinz Heisler in the book "Advanced Engine Technology", published by the Society of Automotive Engineers, Inc. in 1995 and reprinted in 2003, a typical gasoline-driven internal combustion uses approximately 30% of the energy contained in the fuel. The remaining 70% are lost, 38% thereof as energy in exhaustion gases. The employment of the arrangements and concepts presented in this invention increases the power delivered to the crankshaft and improves the energy efficiency of the motor. BRIEF DESCRIPTION OF THE FIGURES Figure 1 illustrates a part of a conventional four-stroke reciprocating engine, showing chiefly a cylinder with its piston, the rod/crankshaft system and the intake and discharge valves.

Figure 2 shows a P x V (pressure x volume) graph inside the cylinder of figure 1 and the portion of energy wasted in the discharge of gases to the atmosphere.

Figure 3 shows, in its various positions, several types of rotating- piston positive-displacement rotary flow machines. Figure 3a shows the sliding-vane machine, figure 3b shows the semi-articulated vane machine, in 3c shows the rolling piston and in 3d the rotor with swinging wing. In 3e one shows the external shaft piston, in 3f the fixed-vane machine with two rotors, in 3g the tilting-vane machine with two rotors and in 3h the tilting-vane machine with one rotor.

Figure 4 shows a part an internal combustion engine with a rotating-piston positive-displacement rotary flow machine coupled to its discharge or exhaust.

Figure 5 shows a sequence of operations of the engine cylinder and a rotating-piston positive-displacement rotary flow machine coupled to each other, showing the synchronism between them.

Figure 6 shows schematic diagrams of conventional prior-art engines, in 6a the aspirated engine, in 6b the supercharged engine and in 6c an engine with a turbo-charging system. Figure 7 uses the same type of schematic diagram of figure 6 to illustrate the engines with a rotating-piston positive-displacement rotary flow machine coupled to each of its cylinders on the discharge side, for aspirated engines in 7a, supercharged engines in 7b and turbo-charged engines in 7c.

Figure 8 shows a graph representing the pressure inside the cylinder versus the crankshaft turn angle for two engines, an aspirated one and a supercharged one.

Figure 9 shows the same type of graph of figure 8, in this case for the cylinder of the supercharged engine and with the rotating-piston positive-displacement rotary flow machine coupled to its discharge. The conventional supercharged engine of figure 8 is again represented for the purpose of comparison.

Figure 10 represents the mechanical work accumulated during a complete alternative-piston cycle of a conventional engine.

Figure 11 shows not only the mechanical work accumulated by the reciprocating piston, but also by the rotating-piston coupled to it. The mechanical work gain in each cycle obtained with the two pistons coupling is shown. Figure 12 shows an arrangement of the coupling of a rotating- piston positive-displacement rotary flow machine to the inlet of the cylinder of a conventional engine, for the extension of its intake stroke.

Figure 13 shows various phases of the operation of the cylinder and the rotary flow machine of figure 12 coupled to it. One can note the characteristics of the synchronism between them.

Figure 14 represents schematically the engine with rotating- piston positive-displacement rotary flow machines coupled to its inlet, figure

14a, with the heat exchanger between the rotary flow machines and the cylinders, figure 14b, and simultaneous couplings to the inlet and to the discharge of each cylinder, figure 14c.

Figure 15 represents the synchronized coupling of the conventional cylinder of an internal combustion engine to an auxiliary cylinder, also with a reciprocating piston, the latter with double action, for extension of the expansion stroke of the engine piston. DETAILED DESCRIPTION OF THE FIGURES

In a conventional configuration, as partly illustrated in figure 1 , the prior-art internal combustion engine is composed of piston 1 , which works with an alternative linear motion within the cylinder 2, which in turn is constructed in a block 3. The rod 4 transfers the alternative motion of the piston 1 to the crankshaft 5, which turns with angular velocity (V), in the example presented in clockwise direction. In its alternative motion the piston 1 oscillates between the top dead center (TDC) and the bottom dead center (BDC). At these points its linear velocity is null. For the purposes of references one considers the angle (θ) of turn of the crankshaft equal to zero at the TDC at the beginning of the intake of air or air/fuel mixture. The internal region of the cylinder 2 over the piston 1 is called combustion chamber 6. It is provided with an intake valve 7, which is connected with the intake header 8 and the discharge valve 9 connected to the discharge header 10. These valves and headers are normally built on the cylinder head 11. The drive for opening and closing the valves is made by the camshaft 12, the motion of which is synchronized with the rotation of the crankshaft 5 at an angular velocity (V/2) equal to the half its own. Sprayed-liquid-fuel injectors may also be installed on the cylinder head, injecting it directly into the combustion chamber 6 or into the intake header 8. Some fuels, like gasoline, alcohols and natural gas, require an ignition plug 13 to start the burning. On the other hand, diesel dispenses with such a component, since it has self- ignition under high pressures.

Engines with multiple cylinders 2 and pistons 1 connected to the same crankshaft 5 are common.

In the intake stroke that begins with the piston 1 at the top dead center (TDC) and ends when it reaches the bottom dead center (BDC), air or air/fuel mixture is sucked into the combustion chamber 6. In order to increase the amount of mass taken in conventional engines, the intake valve 7 is opened just before the stroke begins and is closed just after the stroke ends.

In the compression stroke, with intake valves 7 and discharge valves 9 closed, the air/fuel mixture within the cylinder 2 is compressed to a volume smaller than the initial one by the rising motion of the piston 1.

Nearby the end of the compression stroke the ignition occurs and the pressure in the cylinder increases considerably. The combustion quickly propagates in the whole air/fuel mixture. The expansion stroke begins with the piston 1 at the top dead center (TDC) and ends at the bottom dead center (BDC). The high pressure of the combustion gases pushes the piston 1 down and the rod 4 forces the crankshaft 5 to turn. When the piston 1 comes close to the bottom dead center (BDC), the discharge valve 9 opens to start the exhaustion process and reduce the pressure inside the cylinder 2.

At the exhaustion stroke the discharge valve 9 remains open while the piston 1 moves upwards to the top dead center (TDC), expelling the remaining gases from the cylinder 2.

Many rotary engines, such as the one developed by Wankel with trochoid pistons, use the four strokes described above as well, although with a different geometry.

Of the four strokes of a conventional engine, only one delivers significant torque and power to the crankshaft 5, the expansion one. The three others, in general, consume energy. When the engine is supercharged, the intake stroke delivers a minor power to that shaft.

The irreversible expansion of the gases at the end of the expansion stroke is known in the art as "blowdown". As already mentioned by Heinz Heisler, approximately 38% of the energy of the burnt fuel is wasted as energy contained in the exhaust gases. Figure 2 shows a theoretical PV (pressure x volume) diagram for a cylinder 2 of the conventional engine described above. The continuous line represents the evolution of the pres- sure inside the cylinder 2 or the combustion chamber 6. The area (A) surrounded by it represents the net mechanical work made available to the engine shaft in the compression-expansion strokes. The dashed line delimits the area (B), which represents the energy wasted in the "blowdown" of the gases at the end of the expansion. At present time, when atmospheric pollution damages are critical and the known petroleum reserves show a worrying limitation, minimizing fuel consumption should be a priority. The ways to achieve such saving go through the decrease in size and weight of engines by increasing their specific power, a technique known as "downsizing", and by increasing their energy efficiency. The present invention meets both requirements. It enables one to take advantage of a fair amount of the energy contained in the gases from combustion at the end of the expansion stroke, by extending it, transforming it into usable energy by the engine crankshaft 5.

The flow machines are classified into two main categories: dynamic and positive-displacement machines.

The dynamic ones are continuous-flow rotary machines. Their work chambers are constantly in contact with the inlet and outlet. In compressors or pumps a high-rotation element accelerates the fluid medium as it passes through it, leading it to a high velocity, and then makes use of its kinetic energy to create static pressure. In driving machines the opposite takes place. Examples of dynamic machines are expanding and compressing turbines of a turbo-compressor or "turbocharger" widely employed for supercharging internal combustion engines.

Positive-displacement flow machines are units in which successive volumes of fluid medium are confined in a sealed or closed chamber, the volume of which undergoes periodic physical alteration. This chamber communicates alternately with the inlet and outlet.

Let us consider the rotating-piston 101 positive-displacement rotary flow machines 100 illustrated in the various positions of figure 3. Figure 3a illustrates the sliding-vane machine; figure 3b shows a machine with a semi-articulated vane, an improvement of the previous one. In figure 3c we have the rolling piston, widely used in hermetic compressors for refrigerators and the like. Figure 3d illustrates the rotor with a swinging wing. The machine of figure 3d is known as rotating-piston with external shaft and has a large volumetric capacity. Figure 3f shows a machine with fixed vane. Figures 3g and 3h illustrate machines with tilting vanes with two rotors or one rotor, respectively, object of the patent application BR having the provisional number 000022070017887. The directions of rotation shown in all the positions of figure 3 indicate that those machines are driving ones.

Numberless other constructive forms of rotating-piston positive- displacement rotary flow machines could complement this figure. One should pay attention to the fact that, not by coincidence, all the positive-displacement rotary flow machines 100 illustrated in the various positions of figure 3 show only one rotating-piston 101 per active rotor 102. It is possible to find, for instance, sliding-vane machines with various vanes inserted into the same rotor 102. However, for the objectives of the present invention, it is preferable that they should have only one.

Thus configured, these flow machines 100 have a number of common characteristics. Their rotating motions dispense with the rod/crankshaft system for transmission of torque and power to the main shaft. All of them work with a pressure chamber of varying volume at the front of the rotating-piston 101 , which we will call pressurized chamber 106 and a depressurized chamber 108 on the other side thereof. They have seal areas 105 at the point of closest proximity of the rotor 102 with the housing 103 or between the two rotors 102.

One defines the compressing capability of a positive-displacement flow machine that works compressing gases as its capability of reducing the volume of the pressurized chamber from the beginning of the compression until the end thereof.

In the same way, the extending capability of an expanding positive-displacement flow machine, that is, one that works with its piston being pushed by gases within it, is its capability of increasing the volume of the pressurized chamber from the beginning until the end of a cycle of controlled expansion of those gases.

The mechanical work "W" developed inside a pressurized chamber of varying volume, cases of the combustion chamber 6 of the engine cylinder 2 and of the pressurized chamber 106 of the rotary flow machine 100, can be mathematically calculated by integrating the pressure- versus-volume curve, from the initial volume "Vi" until the final volume "V_f", that is to say,: W = j_Vi ^Vf PdV (equation 1 ).

The volume, in the case of both chambers mentioned above, is closely related to the turn angle of the engine crankshaft 5 and of the rotor 102, respectively, since the positions of the reciprocating 1 and rotating 101 pistons are directly linked thereto.

The mechanical work performed by or on the rotating-piston 101 positive-displacement rotary flow machines 100 is not continuous, but discrete at each rotation. This particularity can be considered a disadvantage of these machines 100, since it produces or requires pulsating flow of gases or other fluids with which they work.

Over decades one tried, without success, to replace reciprocating internal combustion engines with rotary engines.

The present invention presents a different arrangement, where the rotating-piston 101 positive-displacement rotary flow machines 100 are used, not to replace the reciprocating engine, but to complement it. Thus, the pulsating flow described before is no longer a disadvantage and becomes an important synchronized coupling characteristic for the cycles of the two types O

of machine.

Each engine cylinder 2 should have, coupled to it, right after the discharge valve 9 and the discharge header 10, a rotating-piston 101 positive-displacement rotary flow machine 100, as for instance, one of the machines shown in the various positions of figure 3. One should note that these machines are only examples that do not limit the application of the inventive concept presented herein. At first, any type of rotating-piston 101 positive-displacement rotary flow machine 100 that exhibits the characteristics described herein may be used. By way of example, one has opted for using the rotary flow machine of a rotor with tilt vane 100 of figure

3h. An internal combustion engine with multiple cylinders 2 should have multiple rotary flow machines 100 coupled to it, one for each cylinder 2.

The rotary flow machine 100 of figure 4 works synchronized with the engine cylinder 2 to which it is coupled. The motion of its shaft is linked to that of the engine crankshaft 5 through a chain, a tooth belt, a gear or another synchronized-transmission element 109. Its rotor 102 turns at an angular velocity (V/2) equivalent to half the angular velocity (V) of the engine crankshaft 5. The directions of rotation of this example are indicated in figure 4. The synchronized coupling between it and the engine should be such that, when the discharge valve 9 of the cylinder 2 opens at the end of the expansion stroke, discharging the pressure of the gases inside the cylinder 2 into the header 10 to which the rotary flow machine 100 is connected, the rotating-piston 101 will have passed through the opening 110, and the pressurized chamber 106 will be sealed. When the valve 9 opens, a portion of the gases of the combustion chamber 6 fills the pressurized chamber 106, which will be with a small volume at that moment. With continuation of the rotation motions of the crankshaft 5 and of the rotary flow machine 100 the volume of the combustion chamber 6 decreases, by the rising of the piston 1 , while the volume of the pressurized chamber 106 will be increasing. The resulting pressure, at every instant, will be a consequence of the residual pressure inside the combustion chamber 6 at the moment of opening the discharge valve 9, of the volume of the combustion chamber 6, of the volume of the pressurized chamber 106 and of the volume of the discharge header 10, which interconnects these two chambers.

The mechanical work that is consumed in the cylinder 2 by opposition to the rising motion of the piston 1 exerted by the pressure of the gases inside the combustion chamber 6 is compensated or supplemented by the work delivered to the shaft of the rotary flow machine 100 by the rotating- piston 101 that is under action of the pressure of the gases inside the pressurized chamber 106.

The gases contained in the pressurized chamber 106 of the rotary flow machine 100 continue their expansion, forcing the rotating-piston

101 , which will continue to turn and to deliver torque to the shaft of its rotor

102. When the rotating-piston 101 reaches and goes beyond the opening 120, the gases so far retained in the pressurized chamber 106 are released into the exhaust manifold of the engine and may then be used for moving a turbo-compressor.

The rotating-piston 101 continues its rotation motion. Once the scraper 111 has been reached, the tilt vane 104, of which it is part, tilts to retract into the recess 150 of its rotor 102, going beyond its seal area 105. Since the rotation motion of the rotor 102 has angular velocity (V/2) equal to half the angular velocity (V) of the engine crankshaft 5, as the rotating-piston 101 goes beyond the opening 110 the engine cylinder 2 to which it is coupled will again be at the end of the expansion stroke; the discharge valve 9 will open and the sequence of events described above will happen again.

Figure 5 illustrates the sequence of these operations. In the position of figure 5a the cylinder 2 is about to start the exhaustion stroke and the discharge valve 9 is about to open. The rotating-piston 101 has just passed through the opening 110. The exhaustion stroke of the cylinder 2 ends at the position illustrated in figure 5c, when the discharge valve 9 closes. From then on the cylinder 2 is isolated from the rotary flow machine 100 to perform its three other strokes, intake, compression and expansion, while the rotating-piston 101 continues to make the controlled expansion of the gases in the pressurized chamber 106 until the opening 120 is reached, at the position illustrated in figure 5g. Once the seal area 105 is surpassed, as in figure 5h, another cycle begins.

In the case of the rotary flow machine 100 used in the exemplification, the rotation of the rotor 102 causes the vane 104 (and, as a result, the rotating-piston 101 that is part thereof), to work close to the internal surface of the housing 103 and to touch the scraper 111 , by effect of centrifugal force. When the pressurized chamber 106 is sealed, the pressure of the gases inside it will reinforce this action of expelling the vane 104 from its recess 150 towards the internal surface of the housing 103. Other types of positive-displacement rotary flow machines 100 will have their rotating-piston 101 working and going beyond the seal area 105 of different ways, but so as to go beyond the opening region 110 right after having passed the seal area.

Figure 6 shows schematic representations of prior-art internal combustion engines. In figure 6a one illustrates the conventional aspirated engine with the block 3 containing four cylinders 2. The intake header 14 distributes the air or air/fuel mixture among the cylinders 2. The exhaust collector 15 collects all the gases from the four cylinders 2 and leads them to the atmosphere. Figure 6b shows an engine supercharged by the compres- sor 201 , called also "supercharger", which is driven by coupling to the crankshaft 5. Figure 6c shows an engine turbo-charged by the expanding 301 and compressing 302 turbine assembly.

In the various positions of figure 7, one presents schematic diagrams similar to those of figure 6, but where the internal combustion engines have rotating-piston 101 positive-displacement rotary flow machines 100 individually coupled to the discharge of each of their cylinders 2, according to concept of this invention. In figure 7a the engine is aspirated, in 7b it is supercharged and in 7c it is turbocharged.

The graph of figure 8 represents the pressure inside the combustion chamber 6 of a cylinder 2 of a conventional engine as a function of the angle of turn of the crankshaft 5. The continuous line is used to represent a naturally aspirated engine and the dashed line is used to represent a supercharged engine. One observes the four strokes theoretically represented in the graph. For angle (θ) from 0 to 180^Q one has the intake stroke with pressure equal to the atmospheric pressure less a minor drop at the intake valve 7, for the aspirated engine. In the supercharged engine the pressure will be equal to the pressure delivered by the compressor 201 to the intake collector 14 less a minor drop in that valve 7. The compression occurs between 180^s and 360°, when, by rising of the piston 1 , the volume of the combustion chamber 6 decreases. Moments before this stroke ends, ignition takes place, starting the combustion. From 360⁹ to 540⁹ expansion occurs, a stroke in which the greatest part of the mechanical work of the conventional engine is generated by the pressure exerted by the gases inside the combustion chamber 6 on the piston 1 in downward movement. In the last stroke, the exhaust one, from 540⁹ to 720^g, the piston 1 expels the gases from the combustion chamber 6. There is a great drop in pressure, which we conventionally call "blowdown". The discharge occurs into the discharge header 10, which is connected to the atmosphere through the manifold or collector 15 and the exhaust pipeline. The work consumed by the piston 1 in this stroke is little and proportional to the overpressure necessary to overcome the loss of charge in the discharge valve 9, in the discharge header 10, in the collector 15 and in the exhaust pipeline. Engines provided with turbo-chargers will have higher pressure in this phase due to the overpressure necessary for causing the turbine 301 of that component to turn. There is consumption of mechanical work in this phase. The energy contained in the gases is wasted for the most part. Figure 9 again reproduces, in dashed line, the pressure in the cylinder 2 of the supercharged conventional engine of figure 8, for comparison purposes. In continuous line one represents the pressure in an analogous cylinder 2, but coupled, in a synchronized manner, to a rotating- piston 101 rotary flow machine 100, which extends its expansion stroke, as described above. This engine is also supercharged in the same conditions of the conventional one. The pressure lines are coincident in the first three operational strokes of the cylinder 2, since in them there is no contact of the gases of the inside of the combustion chamber 6 with the rotary flow machine 100 connected to it. However, one should note the difference in the last stroke, the exhaustion one. In the engine with synchronized coupling, when the discharge valve 9 is opened there is no direct discharge to the exhaust collector 15. On the contrary, the gases of the cylinder 2 are discharged to the rotating-piston 101 rotary flow machine 100. There is a certain drop in pressure, but not to the levels observed for the conventional engine. The resulting pressure will be a function of the ratios of the volumes of the combustion chamber 6, of the pressurized chamber 106 and of the header 10 of interconnection between them. It is this pressure that will be used by the rotating-piston 101 for generating work and delivering additional torque to the engine crankshaft 5 via the synchronized transmission element 109.

Figure 10 shows the graph of the mechanical work accumulated by the reciprocating piston 1 of the supercharged conventional engine of figure 9, along a complete cycle of the four operation strokes of the cylinder 2 of the engine. The line sued to represent it is dashed. One should note the gain obtained in the intake stroke by the overpressure delivered by the supercharger 201. In the compression, the reciprocating piston 1 has to overcome the resistance offered by the gases that are being compressed and so it consumes energy. In the expansion the combustion gases, under high pressure, push the reciprocating piston 1 downwards, delivering a large amount of mechanical work to the crankshaft 5. Due to the little overpressure, in the exhaust phase there is an insignificant consumption of energy. All the work accumulated so far by the reciprocating piston 1 remains almost unchanged during this stroke. The total accumulated mechanical work, as represented in this graph, represents the energy delivered to the crankshaft 5 in each complete cycle, that is to say, at every two rotations thereof. Losses by friction, thermal losses, losses by leakage and others are not considered herein. The mechanical work developed in the unit of time is named powelhe graph of figure 11 repeats the study on the accumulated mechanical work, now for the cylinder 2 of figure 10 coupled to a rotary flow machine 100 for extension of its expansion stroke. The dashed line represents the work of the reciprocating piston 1. The dash-dot line represents the work of the rotating-piston 101 coupled to it and the continuous line represents the sum of the works of the two types of piston.

In the first three strokes of the cycle, the behavior of the reciprocating piston 1 is identical to that of a conventional engine illustrated in figure 10. In the exhaustion, however, since its cylinder 2 is coupled to a rotating-piston 101 rotary flow machine 100, there will be a controlled expansion of the gases from combustion. This holding of the gases generates additional energy consumption for expelling them from the inside of the combustion chamber 6, since the latter is pressurized. However, this loss is compensated or surpassed by the work generated on the rotating- piston 101. One should note that the work on this piston 101 begins when the discharge valve 9 is opened at the end of the expansion stroke. During the whole exhaustion stroke the pressure of the combustion gases will take up energy from the reciprocating piston 1 and will deliver energy to the rotating- piston 101. Once the exhaustion stroke has finished, the discharge valve 9 will close, the reciprocating piston 1 will return to the beginning of its cycle, with the intake of a new amount of fresh air, but the rotating-piston 101 will continue turning, with the pressure of the gases still generating work that will be delivered to the shaft of the rotary flow machine 100, which, by synchronized coupling 109, will deliver it to the engine crankshaft 5. For the purposes of illustration, the work exerted on the rotating-piston 101 ceases coincidently with the end of the compression stroke of the engine cylinder 2. These events do not necessarily need to coincide. The work on the rotating- piston 101 ceases when the gases inside the pressurized chamber 106 are discharged into the exhaust pipeline through the opening 120. This time should be the latest possible, for better utilization of the energy of the gases inside the rotary flow machine 100. The rotating-piston 101 should, after that discharge, go beyond the seal area 105 and the opening 110 to receive the gases from the new cycle of the engine cylinder 2.

The "GAIN" illustrated in figure 11 represents indirectly the increase in power that is obtained by employing the configuration or coupling arrangement presented so far in this invention. The work delivered to the engine crankshaft 5 is increased at every cycle and, as a result, the power developed by the engine as well, consuming the same amount of fuel, since the reciprocating cylinder 2 used in the example is the same of the previous conventional configuration. Gain in power without an increase in fuel consumption means an increase in efficiency.

The gains in power and efficiency of the engine will be a function of the correct coupling of the rotary flow machine 100 with the cylinder 2 and its reciprocating piston 1. The ratio between the maximum volumes of the pressurized chamber 106 to the combustion chamber 6 plays a fundamental role. A too little ratio would lead to an almost null "GAIN", since the gases would have little expansion inside the rotary flow machine 100, being discharged into the opening 120 with still high residual pressure, thus delivering little energy to the rotary flow machine 100 shaft and, as a result of the coupling 109, to the engine crankshaft 5. The resistance to the rising of the reciprocating piston 1 would be big.

On the other hand, a very great ratio of volumes between those chambers would be harmful. The larger the final volume of the pressurized chamber 106 the larger its initial volume, which would provide an accentuated drop in pressure at the time of opening the discharge valve 9, with loss of the gases energy in the process of irreversible expansion similar to the "blowdown" of the conventional engine described before.

The best coupling between the engine cylinder 2 and the rotating-piston 101 rotary flow machine 100 is obtained when the following conditions are met:

• by the time of the discharge valve 9 opening at the end of the expansion stroke, the volume of the pressurized chamber 106 and the volume of the header 10 between it and the discharge valve 9 are to be as small as possible; and • the rotary flow machine 100 is to have an internal diameter of the housing 103, rotor 102 length and ratio between the housing 103 internal diameter and rotor 102 outside diameter so as to provide it with a sufficient extending capability to cause the volume of the pressurized chamber 106 at the end of the controlled expansion to such a value that causes pressure of the gases inside it at the moment of releasing these cases to the exhaust tubing, by passage of the rotating-piston 101 through the opening 120, only slightly higher than the atmospheric pressure.

The larger the cylinder 2, the larger the rotary flow machine 100 should be. In the same way, for cylinders 2 of the same size, the larger the supercharging pressure the larger the amount of gas at the discharge and, consequently, the larger the needed extending capability of the rotary flow machine 100.

Computer tools for optimizing complex systems of multiple variables such as, for example, the "Solver", can be used for identifying the length and diameters more suitable for rotor 102 and housing 103 for determined constructive and operational conditions of the engine cylinder 2, such as cylinder displacement, compression rate, supercharging pressure, type of fuel, ignition point, dead volumes, rotation speed, times of opening of the valves 7 and 9, temperatures of the gases, losses of charge, etc.

In an analogous way, one may employ the inventive concept of individualized synchronized coupling for each cylinder 2 to a rotating-piston 101 rotary flow machine 100 for extension of the intake stroke in supercharging engines. In this case, the machines illustrated in the various positions of figure 3 will function as compressors and for this purpose their rotation directions will be inverted. In figure 12, one illustrates a coupling of this type. The rotary flow machine 100 used as an example has two rotors 102 with fixed vanes. Other types of rotating-piston 101 positive- displacement rotary flow machines 100 that have the coupling characteristics described herein may be used.

The rotary flow machine 100 is coupled right before the intake valve 7 and the intake header 8. It functions synchronized with the cylinder 2 of the engine to which it is coupled. The movement of its shaft is linked to that of the crankshaft 5 by means of a chain, a toothed belt, a gear or another synchronized-transmission element 109. Its rotors 102 turn at an angular velocity (V/2) equivalent to half the angular velocity (V) of the engine crankshaft 5. The rotation directions for this example are indicated in figure 12. The synchronized coupling between the rotary flow machine 100 and the engine cylinder 2 should be such that, when the intake valve 7 of the cylinder 2 closes at the end of the intake stroke, the rotating-pistons 101 will have just reached the openings 110.

With this configuration and coupling characteristic the pressurized chamber 106 will make a controlled pre-compression of air or air/fuel mixture, accumulating pressure even before opening the intake valve 7 and will deliver to the cylinder 2 always the same amount of air, independently of the engine rotation velocity (V). The delay in the response of acceleration of the engine rotation is significantly reduced.

Figure 13 shows the synchronized sequence of the events described. In figure 13a the fixed vanes with rotating-pistons 101 are crossing over the proximity region between the two rotors 102. From the position shown in figure 13b the rotating-pistons 101 start accumulating pressure in the pressurized chamber 106. The intake valve 7 is still closed. Therefore, the cylinder 2 is isolated from the rotary flow machine 100, free for performing the compression, expansion and exhaustion strokes. Right before the beginning of the intake stroke, figure 13f, the intake valve 7 opens and the gases pre-compressed in the pressurized chamber 106 are taken in the combustion chamber 6 of the cylinder 2. When the cylinder 2 finishes the intake stroke, figure 13h, the intake valve 7 closes and the rotating-piston 101 finishes the pre-compression, passing through the opening 110. A new cycle is about to begin.

In this case of using a rotating-piston 101 positive-displacement rotary flow machine 100 for individual supercharging of each cylinder 2 of the engine, the best coupling between them occurs when the following conditions are met: • by the time of the intake valve 7 closing at the end of the intake stroke, the volume of the pressurized chamber 106 and volume of the header 8 between it and the intake valve 7 are to be as small as possible; and • the rotary flow machine 100 is to have an internal diameter of the housing 103, rotor 102 length and ratio between the internal diameter of the housing 103 and external diameter of the rotor 102 dimensioned so as to provide it with a sufficient compressing capability to reduce the volume of the pressurized chamber 106 at the end of the controlled pre-compression, to a value such that it causes pressure of the air or air/fuel mixture inside it, inside the intake header 8 and in the combustion chamber 6, right before closing the intake valve 7, to be at the pre-determined level of supercharging of the engine. The compression of the air in any compressor, in general, raises its temperature. One can employ, between each pre-compressing rotary flow machine 100 and the cylinder to which it is coupled, a heat exchanger 215, also called "intercooler", to reduce its temperature.

As a natural consequence of what has been described so far, each engine cylinder 2 can work with a rotating-piston 101 positive- displacement rotary flow machine 100 coupled in a synchronized way to its inlet and another to its outlet.

Figure 14a shows a schematic diagram of an internal combustion engine with pre-compressing rotary flow machines 100 coupled to its inlet. In figure 14b one has employed a heat exchanger 150 between each pre- compressing rotary flow machine 100 and its respective cylinder 2. In figure 14c we have a synchronized coupling on both sides of the cylinder 2, inlet and outlet.

By-pass valves, relief valves and other types may be employed in the interconnection tubes before and after the rotary flow machines 100 or even in themselves, as widely used in conventional engines. One can drive the flow of gases to the atmosphere or to recirculation. One can control pressure limits, establishing whether, for instance, a maximum value above which the excess would be discarded to the atmosphere or to another part of the equipment. The employment of such procedures is an obvious application of the prior art and so it is not discussed in this document.

The expansion and intake strokes of the cylinder 2 of a conventional engine can be extended by employing auxiliary reciprocating cylinders 402, which are also positive-displacement flow machines, coupled to it in an individual and synchronized manner, instead of the rotary flow machines 100 used so far in the development of the concept of this invention. Although it is of a more complex construction due to the rod/crankshaft system, the gains in power and efficiency will be similar to those already described, while the losses by pressure leakage will be potentially smaller. One may employ, for coupling, an auxiliary cylinder 402 with a simple or double-action piston 401. The latter is the most recommended one, by virtue of its better volumetric utilization, since it will be able to work extending one or two strokes of the main cylinder 2, in both its rising and descending movements.

An arrangement for extension of the expansion stroke of the engine cylinder 2 employing auxiliary cylinders 402 is represented in figure 15. The discharges of cylinder 2 occur alternatively to each side of the piston 401 that works in the cylinder 402. This occurs by employing a valve directing the discharge gases, now to one side of the double-action piston 401 now to the other side, or, as illustrated, by using two independent discharge valves 9 connected to equally independent discharge headers 10. The discharge valves 9 open at alternating cycles of the cylinder 2. For this purpose, its crankshaft 12 works with angular velocity (V/4) equal to one fourth of the velocity (V) of the engine crankshaft 5.

The crankshaft 405 works coupled and synchronized with the main crankshaft 5, by means of a synchronized-transmission element 109, with angular velocity (V/4) equivalent to one fourth of its velocity. The piston 401 moves upwards in its cylinder 402 making the controlled expansion of the gases from the cylinder 2, which are in the bottom pressurized chamber 406, delivering mechanical energy to the shaft 405. Upon reaching its top dead center, a valve located after the lower discharge opening 420 opens and remains open during the descending movement of the piston 401 for discharge of the already expanded gases. At the moment when the piston 401 is at its top dead center, the gases of the next cycle of the same cylinder 2 will be discharged in the top pressurized chamber 406. The piston 401 starts its descending movement, expanding those gases and delivering mechanical energy to the shaft 405 and, indirectly, to the main crankshaft 5.

The preferred arrangement for extension of an internal combustion engine stroke is that shown in figure 7b. With this arrangement, one obtains the supercharging of the engine by employing the compressor 201 , known also as "supercharger", which increases its power and raises the "blowdown" pressure, increasing the gains in the positive-displacement rotary flow machines 100 that are individually coupled to the discharge of each of its cylinders 2 and, consequently, further increasing its power. Interrupting the expansion of the gases in the pressurized chambers 106 of the rotary flow machines 100 so that there will be a residual overpressure that could cause the expanding turbine 301 of figure 7c to turn is not the most advisable procedure, because the positive-displacement machines tend to have better mechanical yield than the dynamic ones. The gain in efficiency that is obtained with the turbine 301 would not be compensated for the energy wasted by premature release of the gases from the inside of the rotary flow machines 100.

Claims

1. A four-stroke internal combustion engine, composed of one or more assemblies of cylinder (2) and reciprocating piston (1 ), the linear motion of the latter being transferred to the crankshaft (5) through rods (4), characterized in that its expansion stroke is extended by controlled expansion of the gases discharged from the combustion chamber (6) of each cylinder (2) after the opening of the discharge valve (9) and also after the closing thereof in a rotating-piston (101) positive-displacement rotary flow machine (100), which is individually coupled to the discharge of each cylinder (2) and the work developed therein is transmitted to the engine crankshaft (5) through synchronized-transmission element (109).

2. An internal combustion engine according to claim 1 , characterized in that the rotating-piston (101) positive-displacement rotary flow machine (100), which is coupled to each cylinder (2), has a movement synchronized with the turn of the crankshaft (5), with such a synchronization that the rotating-piston (101 ) goes beyond the opening (110) that links the rotating machine (100) to the engine cylinder (2) at the moment when the discharge valve (9) of the cylinder (2) is opened at the end of the expansion stroke.

3. An internal combustion engine according to claims 1 and 2, characterized in that the discharge header (10) and the rotating-piston (101) positive-displacement rotary flow machine (100) coupled to the engine cylinder (2) are arranged, dimensioned and built in such a way, that at the moment when the discharges valve (9) opens at the end of the expansion stroke, the volumes of the pressurized chamber (106) and of the discharge header (10) between it and the discharge valve (9) of the engine cylinder are as small as possible.

4. An internal combustion engine according to claims 1 and 2, characterized in that the rotating-piston (101 ) positive-displacement rotary flow machine (100) coupled to the engine cylinder (2) has the rotor (102) length, the housing (103) inner diameter and the ratio between this diameter and the rotor (102) outer diameter dimensioned so as to provide it with an extending capability sufficient to bring the volume of the pressurized chamber (106) at the end of the controlled expansion to such a value that causes the pressure of the gases inside it, in the beginning of the release thereof to the exhaust collector (15) at the moment when the rotating-piston (101 ) passes through the opening (120), to be only slightly higher than the atmospheric pressure.

5. A four-stroke internal combustion engine, composed of one or more assemblies of cylinder (2) and reciprocating piston (1), the linear motion of the latter being transferred to the crankshaft (5) through rods (4), characterized in that its intake stroke is extended by controlled pre- compression of the air or air/fuel mixture that will be introduced in the combustion chamber (6) of each cylinder (2) before the intake valve (7) opens and during its actuation until it closes, in a rotating-piston (101 ) positive-displacement rotary flow machine (100), which is individually coupled to the entrance of each cylinder (2) and the rotation of which is synchronized with the engine crankshaft (5) through synchronized-transmission element (109).

6. An internal combustion engine according to claim 5, characterized in that the rotating-piston (101 ) positive-displacement rotary flow machine (100), which is coupled to each cylinder (2), has a movement synchronized with the turn of the crankshaft (5), with such a synchronization that, when the intake valve (9) of the cylinder is closing at the end of the intake stroke, the rotating-piston (101 ) will be simultaneously reaching the opening (110).

7. An internal combustion engine according to claims 5 and 6, characterized in that the intake header (8) and the rotating-piston (101) positive-displacement rotary flow machine (100) coupled to each engine cylinder (2) are arranged, dimensioned and built in such a manner, that, at the moment when the intake valve (9) is closing at the end of the intake stroke, the volumes of the pressurized chamber (106) and of the intake header (8) between it and the intake valve (7) of the engine cylinder (2) are as small as possible.

8. An internal combustion engine according to claims 5 and 6, characterized in that the rotating-piston (101 ) positive-displacement rotary flow machine (100) coupled to each engine cylinder (2) has the rotor (102) length, the housing (103) inner diameter and the ratio between this diameter and the rotor (102) outer diameter dimensioned so as to provide it with a compressing capability sufficient to reduce the volume of the pressurized chamber (106) at the end of the controlled pre-compression to such a level that causes the pressure of the air or air/fuel mixture inside it, inside the intake header (8) and the combustion chamber (6), at the end of the intake stroke, to be at the predetermined level of supercharging of the engine.

9. An internal combustion engine according to claim 1 or 5, characterized in that the rotating-piston (101 ) positive-displacement rotary flow machine (100), which is coupled to each cylinder (2), has preferably one rotating-piston (101) per active rotor (102).

10. An internal combustion engine according to claim 9, characterized in that the rotating-piston (101 ) positive-displacement rotary flow machine (100), which is coupled to each cylinder (2), has a movement synchronized with the turn of the crankshaft (5) at an angular velocity (V/2) equal to half the angular velocity (V) of that shaft.

11. A four-stroke internal combustion engine, composed of one or more assemblies of cylinder (2) and reciprocating piston (1 ), the linear motion of the latter being transferred to the crankshaft (5) through rods (4), characterized in that its expansion stroke is extended by controlled expansion of the gases discharged from the combustion chamber (6) of each cylinder (2), after the discharge valve (9) opens and also after it closes, in a rotating-piston (101) positive-displacement rotary flow machine (100), which is individually coupled to the discharge of each cylinder (2), the work developed therein being transferred to the engine crankshaft (5) through a synchronized-transmission element (109), and also its intake stroke is extended by controlled pre-compression of the air or air/fuel that will be introduced in the combustion chamber (6) of each cylinder (2) before the intake valve (7) opens and during its actuation until it closes, in a rotating- piston (101 ) positive-displacement rotary flow machine (100), which is individually coupled to the inlet of each cylinder (2) and which has its rotation -IvJ

synchronized with the engine crankshaft (5) through a synchronized- transmission element (109).

12. An internal combustion engine according to claim 5 or 11 , characterized in that a heat exchanger (250) is employed between each rotating-piston (101) positive-displacement rotary flow machine (100) that pre-compresses air or air/fuel mixture and the cylinder (2) to which it is coupled.

13. A four-stroke internal combustion engine, composed of one or more assemblies of cylinder (2) and reciprocating piston (1 ), the linear motion of the latter being transferred to the crankshaft (5) through rods (4), characterized by having auxiliary reciprocating cylinders (402) instead of rotating-piston (101) positive-displacement rotary flow machine (100), individually coupled to the discharge of its cylinders (2) for extending the expansion stroke, the auxiliary reciprocating cylinders (402) being of extending capability similar to that of rotary flow machines (100), with synchronism with respect to the rotation of the crankshaft (5) and to the opening of the discharge valve (9) at the end of the expansion stroke, adequate to this configuratiorl.4. A four-stroke internal combustion engine, composed of one or more assemblies of cylinder (2) and reciprocating piston (1 ), the linear motion of the latter being transferred to the crankshaft (5) through rods (4), characterized by having auxiliary reciprocating cylinders (402), instead of rotating-piston (101 ) positive-displacement rotary flow engines (100), individually coupled to the inlet of its cylinders (2) for extending the intake stroke, the auxiliary reciprocating cylinders (402) being of compressing capability similar to that of rotary flow machines (100), with synchronism with respect to the rotation of the crankshaft (5) and to the closing of the intake valve (7), at the end of the intake stroke, adequate to this configuration.