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(11) | EP 1 503 035 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Rotary thermal volumetric internal combustion engine (rotinmotor (rim)) |
| (57) The present invention consists in a thermal internal combustion engine whose main
pieces accomplish a flat rotation movement. The basic pieces that characterize the engine and its operation are: Stator.- Is the external casing of the engine. Stay fixes, the combustion is accomplished inside. It is the equivalent to the block of the engine in alternative engines. Rotor.- Is a piece lodged inside the stator, that accomplishes a complete circular movement. Stay fixes and inside it is accomplished the combustion. It is the equivalent to the unit piston - connecting rod in alternative engines. The rotation movement described by the rotor inside the stator permits to define variable volumes into stator lobes of equal form that the piston in the interior of the cylinder of a classic alternative motor of equal form that the piston in the interior of the cylinder of a classic alternative motor. The applications are the same that the existing alternative thermal motors at present. |
Sector of technique
[0001] The invention is straddled in the technical sector of volumetric thermal internal combustion engines.
State of technique
[0002] At present, most of the volumetric thermal engines existing are alternative , that is to say, the compression as well as the expansion of the work fluid within the combustion chamber are effected through the alternative movement of a piston inside a cylindrical chamber.
[0003] Throughout the history, many attempts of creation of a rotary engine have been produced, being maybe the one designed by the german engineer Félix Wankel which get greater success, arriving to be produced and being incorporated the engine by him devised in cars and motorcycles, existing at present commercial cars that carry a rotary engine.
[0004] Nevertheless, a series of drawbacks, such as the greater cooling requirements, the limitation of the compression ratio, the troubles on elements of sealed, etc...have caused that this engine may not have had the development that is deserved, mainly by the great innovation and the huge wit that represents.
[0005] The rest of existing creations at present, even though emphasize by their ingeniousness, have not acquired an important development as consequence of some or various technical characteristics that hinder their commercial profitability.
[0006] The technical troubles outlined with the design of a rotary engine consists in the creation of a geometrical piece of the engine block or stator avoiding piston or rotor accomplish a rotary movement that generate a variable volume as a classic alternative engine.
[0007] The objective is the piston and connecting rod alternative movement elimination within the chamber, movement that needs to be converted into a rotary movement, improving characteristics and performance, thermal to mechanical energy conversion alternative mechanism most used at present.
Detailed description of the invention
[0008] The present invention consists in a thermal internal combustion engine whose main pieces accomplish a flat rotation movement, therefore in the description below detailed we show the configuration of the different pieces in the plan of the paper, which coincides with the plane of the movement.
[0009] The basic pieces that characterize the engine and its operation are:
- Stator.- Is the external casing of the engine. Stay fixes, the combustion is accomplished inside. It is the equivalent to the block of the engine in alternative engines. Its geometric limit profile is defined by the outer involute of the curve that defines the limit profile of the rotor, so stator and rotor stay always in touch during the circular movement of this. The shape of the stator depends on the rotor choice. In the case described, being the rotor an epitrochoid of 2 lobes, stator shape is similar to a clover, as a consequence of having 3 identical combustion chambers with 120° of difference between them. In its central zone has a gap in which is lodged a gear in whose interior turns the corresponding gear of the rotor.
- Rotor.- Is a piece lodged inside the stator, that accomplishes a complete circular
movement. Stay fixes and inside it is accomplished the combustion. It is the equivalent
to the unit piston - connecting rod in alternative engines. Its limit profile is defined
by an epitrochoid of 2 lobes, whose parametrics cartesians equations are:
[0010] The particular case that we are describing is an epitrochoid of 2 lobes (a = 2×b, so a+b = 3b).
- The parameter b is the characteristic parameter of the epitrochoid, while e is designated eccentricity and its maximum value to define a useful rotor is 3/5b (in case a=2b), value that will be taken later with the purpose of defining the characteristics and properties of the mechanism.
[0013] The rotation movement described by the rotor inside the stator permits to define variable volumes into stator lobes whose value for each lobe oscillates between 0 and 9√13 x be x B, where B is the perpendicular dimension to the plane of the movement.
[0014] So, the cited rotor rotation movement inside the stator produces some variable volumes into stator combustion chambers similar at those which would produce 3 cylinders with 120° of difference in an alternative engine.
[0015] The characteristics of the rotary movement above mentioned are:
1.- The main pieces that define it accomplish a rotation movement.
2.- Accomplishes 1 complete four-stroke thermodynamic cycle (intake, compression, explosion and expansion, and exhaust) with 1 turn of the rotor, when designed as four stroke engine, or accomplishes 2 complete thermodynamic cycles for each rotor turn when designed as two -stroke engine; in both cases, when said 1 or 2 cycles for each rotor turn, it means for each stator lobe, so, it accomplishes 3 or 6 thermodynamic cycles for each rotor turn really, depending on the four or two-stroke engine designed.
3.- Accomplishes a complete sweep of exhaust gases, allowing a complete renovation with the load.
4.- The geometry of stator and rotor admits any compression relationship, even ∞, therefore it can operate as provoked ignition engine or as engine of ignition by compression.
5.- Taking into account that an alone piston (rotor) produces the volume variation of three combustion chambers, that the volume of the crankshaft is incorporated within volume of the piston (rotor), and that the volume relationship of the piston/cylinder capacity is approximately 0, 4 for an alternative engine, while in this case is of 0,66, the same engine size would permit practically double cylinder capacity that the alternative one.
6.- The four-stroke corresponding to the complete thermodynamic cycle are accomplished in the same space, therefore the fresh gases contribute to the engine cooling, so the refrigeration requirements are the same that the ones in an alternative engine.
7.- With respect to even motor, lacks the component even motor due to the inertia forces of the masses in alternative movement because there are no masses with alternative movement, nevertheless this component of the even motor does not contribute at all to the net even motor, simply creates large positive and negative oscillations in the total even that increases the vibration and the irregularity. Therefore insofar as this component of the even motor, this rotary engine presents the best of the possible values: 0. On the other hand, the value of the even motor due to the expansion force of the gases is always superior to the corresponding to an equivalent alternative engine, being able to get, by design, theoretically, four times said value, though in practice will be a top limit impossible to obtaining.
- Sealed mechanism.-
[0017] Sealed mechanism that assures the hermeticism of combustion chambers in the rotary engines ranks with the piston rings in alternative engines.
[0018] In the rotary engine, the system that assures the hermeticism is formed by three types of elements:
- The peripheral piston ring installed in the rotor is a cylinder whose interior shape coincides with the rotor limit profile, whose height is B ( perpendicular dimension to the flat of the movement) and whose thickness is of few millimeters. During rotor movement this ring grubs against stator lateral walls, preventing the flight of the gases from the combustion chambers toward the hole generated by the gear ; at the same time is in permanent touch with the lateral seals installed on the stator, preventing this way the passage of the work fluid between combustion chambers.
- The scraper rings installed on the rotor are two rectangular section rigs whose shape coincides with the rotor limit profile, being the rectangular section size of few millimeters. During rotor movement, those rings, (one for each rotor side) grub against stator lateral walls, raising the action of perimetral ring and collecting lubricant oil rests, placed in stator walls.
- The lateral seals mounted in the stator are three rectangular elements disposed in the intersection of the lobes that define the stator and in a way radial, their height is B ( perpendicular dimension to the flat of the movement), their thickness is of few millimeters and the radial dimension is inferior to the thickness of the stator wall ; in their outer extreme they have a dock that through their reaction with the stator, assure the permanent contact of each lateral seal with the peripheral seal installed on the rotor.
- Transmission gears.-
[0019] In each lateral head of the stator, compactly united to them, are both interior cog gears and radio 3e, on those roll the outer cog gears and radio 2e, disposed at both sides of the rotor and rigidly united to this. The whole previously described gears are straight.
[0020] The relationship between the number of cogs of the stator and rotor gear is of 3/2, as consequence of their dimensions.
[0021] The transmission of the rotor movement to the shaft of the engine is accomplished through the linkage of the shaft of the rotor with a radio disk b, concentric with the stator and in perimetral touch with its lateral lids through bearings. This disk would be already the output shaft of the even motor, being its draft speed of - 2ω, where w is the angle draft speed of the rotor, that is to say, the angle speed of the engine shaft is the double in magnitude that the corresponding to the rotor, and in opposite sense.
[0022] In the case of having several stator units assembled sideways, the intermediate radio disks b would be supported in the common wall of the adjacent units, and would take the place of the crankshaft supports in the case of the alternative engines, unless the extreme disks, those which would provide directly the exhaust even.
- Distribution system.-
[0023] The working of the intake and exhaust valves, located diametrically opposed to the perimeter of each lobe of the stator, is accomplished through 3 camshafts whose shafts will be located in the three symmetry shafts of the stator, that is to say, with 120° of difference.
[0024] Each camshaft will accomplish the working of the intake valve/s of one lobe and of the exhaust valve/s of the adjacent lobe.
[0025] Necessary force for the working of the camshafts is accomplished directly from the shaft of the engine through a timing gear.
[0026] The intake valves are in the proximities of the spark plug, for provoked ignition engines, or the injectors in the case of ignition engines by compression, while the exhaust valves are in the opposite extreme, in this way are separated the hottest points from the combustion chamber, exhaust valve and spark plug, permitting its direct cooling with intake air.
[0027] It is feasible the elimination of the distribution system previously described compound by camshafts and intake/exhaust valves, through the arrangement of intake/exhaust ports in the lateral lids of the stator. The optimum situation for the arrangement of these ports is to share the same shaft with the respective lobes so that the intake port is always closer to the stator centre than the exhaust port. The system is similar to the arrangement of the so named ports in an alternative 2 stroke engine.
[0028] In the case of elimination of the valves and the lateral ports arrangement, would be the own rotor the one which would take charge of regulate the intake and exhaust obstructing or letting free the previously mentioned ports. Nevertheless would be necessary, to complement of efficient manner the sweeping, to complement the same with a turbo compressor in the case of the ignition engines by compression, or with a volumetric compressor in the case of the provoked ignition engines. This turbo compressor or volumetric compressor would accomplish the same mission as the thrust that accomplishes the piston in its travelling toward the crankshaft on the gasses in the intake in the case of an alternative 2 stroke engine sweeped by housing.
[0029] The ports and turbo compressor or volumetric compressor arrangement would convert the rotary engine into a 2 stroke engine, with the difference, with respect to the alternative 2 stroke engines that this one would accomplish 2 thermodynamic cycles with one rotor turn, while an alternative 2 stroke engine accomplishes 1 thermodynamic cycle by each turn of the rotor.
- Lubrication system.-
[0030] For the description of the lubrication system we will differentiate between:
Lubrication of lateral sealing elements installed on the stator.
Lubrication of the peripheral ring installed on the rotor.
Lubrication of the engine shaft.
Lubrication of the camshaft elements.
[0031] The lubrication of the previously described elements is accomplished through a closed oil circuit, endowed of a pump and a heat exchanger that will permit to maintain the temperature of the lubricant within some bearable margins for its correct operation.
[0032] The tour of the oil in cooling system starts by the pump, that introduces oil under pressure by an orifice practiced through the shaft, from here it passes inside the rotor shaft, from where, through radial orifices, and impelled by the centrifugal force lubricates stator and rotor gears, and finally is collected by a scraper ring or seal fixed to the rotor (one by each face of the rotor), and peripheral at all times to stator gear, that returns oil to lubrication circuit, after have lost large part of the load supplied by the pump and have acquired a higher temperature as consequence of its contact with the elements of stator and rotor, passing then through a heat exchanger, if the corresponding thermostat proves the sufficient temperature increase, or passing heat exchanger over and going to the second part of the lubrication circuit.
[0033] In this second part, the lubricant goes through the filter and subdivides its flow in three, going parallel to engine shaft to lubricate the camshafts and the lateral elements of sealed installed in the stator, closing finally the circuit going through the pump again.
- Cooling system.-
[0034] Cooling system of the stator.- is conceptually identical to the cooling system of the block of the engine in alternative engines, being able to be projected either air cooling, through the arrangement of the corresponding blades in the periphery of the stator, or water/oil cooling, projecting the walls of the stator so that they could house the conduits of the flowed as a heat exchanger. We are not insisting on describing cooling system of the stator because there is conceptually no difference with the corresponding to alternative engines, on the contrary, we emphasize that, being accomplished the four stroke of the thermodynamic cycle in the same zone of the stator, the fresh air in intake in the case of ignition by compression or the air mixture and fuel evaporated in the case of provoked ignition contribute to the cooling of the combustion chamber as happens in alternative engines, therefore cooling requirements are the same that in these, something which does not occur in other typologies of rotary engines, in those which the intake and compression is accomplished always in a zone of the engine, while the ignition of the mixture, the expansion and the exhaust are produced always in other one, what provokes an important temperature concentration in this second zone, at the same time that a substantial thermal difference between both, therefore a greater entity refrigeration system is required, to guarantee the correct operation.
[0035] Rotor cooling system.- Basically, there are two forms to cooling the rotor. On the one hand, there is the chance to use a lubricant oil and, by the other, it can be employed the own fresh mixture, before proceed to its combustion.
a) Oil cooling.
[0036] With this type of feature, oil is introduced inside the rotor through the engine shaft, traveling the cavities practiced inside it and accomplishing the heat exchange with the hotter parts by effect of the centrifugal force due to the rotation. Being collected thereinafter to be cooled in an external exchanger. As rotor temperature increases proportionally to the revolutions of the engine, the pump that injects oil into the rotor is synchronized with the operation of the engine. Thus, being ticking over, or even with not much revolutions, it is not necessary to inject oil inside the rotor. This synchronization can be obtained with a mechanism directly connected to the crankshaft and one spring that surpass the centrifugal force until a given revolution speed. As of this moment, would be opened according to the engine requirements.
[0037] Designing correctly this system, it can be obtained that the temperature in the surface of the rotor is maintain practically constant (with maximum variations inferior to the 10%).
b) Air cooling.
[0038] It is a much more limited system, employed only in low features engines and, preferably, stationary, in those which can be designed the set for a very concrete revolutions range. In this case fresh mixture is pumped through the rotor, so that it captures the greater possible quantity of heat from this and, thereinafter, the mixture is introduced in the combustion chamber through the intake port.
[0039] Air cooling, in addition to the constructive simplicity, since does not require any heat exchanger as in the case of oil cooling, has a second advantage, since mixture absorbs the heat, is procured a greater vaporization of fuel, however, it increases the resistance in the aspiration, due to a greater load loss and, consequently, it reduces the mixture load arriving to the combustion chamber.
- Cylinder capacity.-
[0040] Cylinder capacity in rotary engine we are dealing with comes by the expression 3 × 9√3 × be × B, where B is the perpendicular dimension to the movement plane, and 9√3 × be × B is the cylinder capacity corresponding to each one of the lobes that shape the stator.
[0041] The value of B is defined by the requirements of necessary external surface to effect the heat exchange that permits engine cooling, since such surface is directly proportional to B, and grows proportionally to b2, therefore the optimum value of B is next to 1,22b.
- Compression ratio.-
[0042] As set out above, stator and rotor geometry admits any compression ratio, even ∞, therefore it can works as provoked ignition engine or as compression ignition engine. This is due to the fact that the geometric configuration of both limit profiles cause that the volume of the combustion chambers are arrived to be cancelled with the rotor turn, therefore it is necessary to practice in the stator a kind of pre-chamber that guarantee a minimal volume of compressed working fluid, therefore, compression ratio is a design parameter that it is not limited of any manner by the mechanism geometry, being able to reach any theoretical value.
[0043] On the other hand, the design of the pre-chamber is not conditioned to geometric limitations of the here described mechanism, therefore in its design there are hydrodynamics criteria that make easier an initial turbulence of the air-fuel mixture creation to favour its ignition and the spread of the flame front, as well as geometry concerning spark plugs or injectors arrangement and intake valves in its case.
[0044] Volumetric evolution inside stator lobes comes given by the expression: V= 9√3/2 x b x e x B x [1 - cos(2γ)]. (In this formula has not been taken into account the volume occupied by the pre-chamber, which simply would be added to the same).
Construction procedure
[0046] The construction procedure is identical to the corresponding to alternative engines, with the differences regarding rotary motor shape, therefore we do not discuss the construction procedure description, being any novelty with respect to the existing current engines manufacture procedure. Just like materials to be employed.
Industrial application
[0047] The industrial applications of the here described rotary engine are the same that have the existing alternative engines, therefore we do not discuss a description of the same.
Description of the drawings
[0048]
Fig. 1. - Stator.
Figure 1 represents stator limit profile for e=3/5b, being the rotor an epitrochoid
of two lobes (a=2b). In which can be observed the main dimensions of the same, as
well as the interior hole corresponding to the circular gear of the same, with a radio
of 1,8b=3e. In the same way, are descibed the differents parts that formed the stator,
distinguish lateral lids, perimetral block and seals between the lobes (green).
Fig.2.- Rotor.
Figure 2 represents rotor limit profile for e=3/5b, being this one an epitrochoid
of two lobes (a=2b). In which can be observed the main dimensions of the same, as
well as the interior projection corresponding to the circular gear of the same, with
a radio of 1,2b=2e.
Fig.3.- Stator and rotor unit.
Figure 3 represents the expansor-compressor mechanism formed by the assembly stator -rotor. In the figure is represented the rotor with a left turned angle of 30°.
Fig.4.- Four stroke engine.
Figure 4 represents in a schematic way a four stroke engine, being detailed the following parts:
[1] - Injector /spark plug.
[2] - Exhaust port.
[3] - Camshaft.
[4] - Intake port.
[5] - Stator.
[6] - Rotor.
[7] - Stator gear.
[8] - Rotor gear.
Fig.5.- Two stroke engine.
Figure 5 represents in a schematic way a two stroke engine, being detailed the following
parts:
[1] - Injector /spark plug.
[2] - Exhaust port.
[4] -Intake port.
[5] - Stator.
[6] - Rotor.
[7] - Stator gear.
[8] - Rotor gear.
Fig. 6.- Cycle as two stroke engine.
Figure 6 represents in a schematic way a thermodynamic cycle operating the rotary
engine as a two stroke engine, see that a complete thermodynamic cycle is accomplished
in one rotor half turn , being detailed the following phases (are described for the
inferior module, in the others two the description is identical):
[1] - Exhaust/ intake.
[2] - Compression.
[3] - Compression.
[4] - Explosion.
[5] - Expansion.
[6] - Expansion.
Fig.7.- Cycle as four stroke engine.
Figure 7 represents in a schematic way a thermodynamic cycle operating the rotary
engine as a two stroke engine, see that a complete thermodynamic cycle is accomplished
in one rotor half run, being detailed the following phases (are described for the
inferior module, in the others two the description is identical):
[1] - Intake.
[2] - Intake.
[3] - Intake.
[4] - Intake.
[5] - Compression.
[6] - Compression.
[7] - Explosion.
[8] - Expansion.
[9] - Expansion.
[10] - Expansion.
[11] - Exhaust.
[12] - Exhaust.
Fig. 8.- Rotor parts.
In figure 8 are represented the different elements that compose the rotor:
[1] - Complete rotor.
[2] - Perimetral ring.
[3] - Scraper rings.
[4] - Rotor body.
[5] - Pinions.
[6] - Bolts.
[7] -Shaft support bearing.
[8] - Shaft pinion.
[9] - Coupling of two rotors.
The curve that defines stator limit profile is the outer involute of the epitrochoid that defines the rotor.
Rotor rotation movement inside the stator, through the corresponding gears linking, generates inside it three chambers of variable volume in function of the rotation angle.