ITRM990350A1 - DEVICE FOR OBTAINING A TWO STROKE ENGINE WITH A CRANKCASE SEPARATED FROM THE TRANSFORMATION SYSTEM OF THE ALTERNATE RECTILINEAL MOTOR IN MOTORCYCLE R - Google Patents

Description

DESCRIPTION

accompanying a patent application for an industrial invention entitled:

"Device for obtaining a two-stroke engine with casing - pump separated from the system for transforming the alternating rectilinear motion into rotary motion of the crankshaft and relative independent lubrication system".

The present invention relates to a device for obtaining a two-stroke engine with casing - pump separated from the system for transforming the alternating rectilinear motion into rotary motion of the crankshaft.

More in detail, the invention relates to a device which allows to separate the crankcase - pump from the motion transformation system.

As is well known, the two-stroke internal combustion engine is mainly used, by virtue of the constructive simplicity and implicit cost-effectiveness, for small propellers to be applied on motorcycles, for outboard motors, small garden machines. In the past it was also widely used in automotive.

It is also known that civil society is currently becoming increasingly aware of the responsibility to conserve the environment.

Therefore, in the aforementioned specific fields of use of two-stroke internal combustion engines, new solutions are sought that allow to reduce pollution, containing it within increasingly narrow limits.

In particular, the pollution in this type of engines is due to the leaks of unburned fuel through the exhaust port, as well as to the lubrication oil, introduced "to lose" in the crankcase - pump and in the cylinder for the lubrication of the moving parts. .

Currently, research has been directed at solutions that seek to reduce unburned fuel leaks through the exhaust port, in particular by providing fuel injection when the wash and exhaust ports are closed.

The results obtained in this direction are not negligible, and various solutions have been the subject of patent applications.

However, as far as the lubrication problem is concerned, it has not yet been solved, in particular in motors with casing - pump.

In fact, for a long time two-stroke engines have existed with washing obtained using washing air compressors external to the system, with the introduction of the gas washing fluid by means of lights and expulsion of the burned gases by means of controlled valves, of the type used in engines. four-stroke.

It is evident that the application of an external compressor for the washing air complicates the proverbial constructive simplicity of the classic two-stroke, so much so that this type of two-stroke (with external compressor, and possibly with controlled valves), is used for large displacement engines and particular uses, including Diesel cycle, but not for small engines.

In order to maintain the characteristics of constructive simplicity, small weight, small dimensions, low construction costs, few moving parts, it is necessary to maintain the casing - pump.

However, it is necessary to eliminate the defect of letting the lubricating oil necessary for the crank mechanism flow in for the conversion of the reciprocating rectilinear motion of the piston into rotary motion of the crankshaft and the oil necessary for lubricating the sliding of the piston skirt against the wall. of the cylinder, and then mix the residues of the lubricating oil with the exhaust gases.

Furthermore, there is increasing talk of the fateful "zero emission" which will very likely become law in a short time in all developed nations.

In light of the above, the Applicant has developed a solution which allows the above problems to be solved.

These and other results are obtained, according to the present invention, by proposing a solution which provides for the subdivision of the internal part of the classic two-stroke engine, i.e. the internal volume of the cylinder - head - volume of the crankcase occupied by the rectilinear motion transformation system. reciprocating piston in rotary motion, in three distinct and separate areas, which we will call respectively "upper hot area" and a "lower hot area" and finally a "cold area", area of the crankshaft parts.

Therefore, the specific object of the present invention is a device for obtaining a two-stroke "crankcase - pump" engine separate from the system for transforming the alternating rectilinear motion into rotary motion of the crankshaft characterized by the fact that an element for separating the volume is provided. inside of the engine, consisting of the head, cylinder and piston assembly, and engine casing, the latter containing the crankshaft and the complex of the mechanism for transforming the linear motion of the piston into rotary motion of the crankshaft, in three distinct areas between them: the first, defined "upper hot zone" formed by the volume delimited by the cylinder head, the cylinder walls, and the piston head. It is evident that this air volume is a function of the position that the piston occupies during operation.

The second called "lower hot zone" formed by the lower part of the piston head, the walls of the cylinder and the walls of the separator element. It is evident that the volume of this zone varies in a complementary way to the volume of the "upper hot zone" as a function of the position that the piston occupies during operation.

When the piston moves towards the P.M.S. (top dead center) the volume of the "upper hot zone" decreases by the same amount as the volume of the "lower hot zone" increases. Vice versa when the piston moves from the P.M.S. to the P.M.I. (bottom dead center).

The "upper hot zone" and the "lower hot zone" are in communication by means of transfer channels, the "lower hot zone" is also in communication with the external environment, by means of the suction duct, to which the combustion air, pure if the fuel is supplied by injection, or mixed with fuel, if it is supplied by means of a carburetor.

The element object of the invention is the separator which, while allowing the piston to be connected to the crankshaft by means of a connecting rod and other device suitable for transmitting the rotary motion of the crankshaft, seals, not allowing the passage of fluid, from the "lower hot zone" to the "cold zone", and vice versa, preventing the lubrication oil of the motion transformation organs and relative supports from flowing from the "cold zone" to the "lower hot zone".

Depending on the type of device connecting the piston to the crankshaft for example if this device is a connecting rod, or a fixed rod connected to the piston, the separator takes on a different shape.

If said connecting device is a connecting rod, the "separator" can consist of an elastic bellows element, the external part of which is fixed to the cylinder, and the internal part to the connecting rod of the engine.

Always according to the invention, between the two fixed parts of the subdivision or separation element a succession of bends of the material can be provided which allow the pendular motion of the connecting rod on the same vertical plane.

Furthermore, supports of the subdivision or separation element can be provided fixed on the cylinder with a perfect seal, also with a perfect seal.

Still according to the invention, said subdivision or separation element provides supports on the connecting rod with a perfect seal, also with a perfect seal.

In particular, said parts of the subdivision or separation element can be constituted by shaped lamellae, of anti-friction material whose internal part, fixed to the supports, slides inside the external lamellae, fixed to the folds of said subdivision or separation element, to allow oscillation of the connecting rod.

In the event that the connecting device between the piston and the motion transformation mechanism consists of a shaft with a preferably circular section, fixed at one end on the lower part of the piston head, and at the other end to a cross head which is connected to the motion transformation elements, the separator assumes a form of circular support suitably fixed to the cylinder, and having in the center a bushing within which the piston shaft slides.

At the upper end there is a sealing gasket which, while allowing the drum to slide, hermetically seals the "lower hot zone" from the "cold zone", preventing both the passage of fluid and the lubrication oil of the "cold zone" "and of the bush itself.

Still according to the invention, said device allows the piston to be guided concentrically with respect to the cylinder, eliminating or minimizing the plunging of the piston skirt on the cylinder wall, obtaining the result of reducing or even eliminating the need for lubrication between the piston and cylinder, said piston being made with a head and with a suitable skirt extended to the only part necessary to cover the exhaust port in the movement phase from the P.M.I. at TDC, said subdivision or separation element being constituted by a sleeve, said piston being provided with a rod suitably sized to be able to slide inside said sleeve.

In particular, said sleeve can consist of a bushing or a ball sleeve which can be duly lubricated for recovery, provided with a suitable sealing system at the end which delimits the lower hot zone from the cold zone.

In a particularly preferred embodiment of the device according to the invention, it can provide a lubrication system which allows the oil recovery lubrication of the piston skirt, located in correspondence with the "lower hot zone" and consisting of a delivery hole and an outlet located on the cylinder, below the transfer exhaust ports, and in communication with the pressure lubrication system, said two cylinder holes being constantly covered by the piston skirt, which at its lower end carries a groove in which an oil scraper ring, called ring, is placed in the position of the piston at TDC, being in correspondence with said two holes, which therefore allow pressurized oil to enter the oil scraper ring, oil which therefore occupies the annular volume in contact with the shirt.

The present invention will now be described, for illustrative but not limiting purposes, according to its preferred embodiments, with particular reference to the figures of the attached drawings, in which: Figure 1 schematically shows a first type of crank mechanism used with the solution according to the 'invention;

Figure 2 schematically shows a second type of crank mechanism used with the solution according to the invention;

Figure 3 schematically shows a third type of crank mechanism used with the solution according to the invention;

Figure 4 schematically shows a first embodiment of the device according to the invention;

figure 5 schematically shows a second embodiment of the device according to the invention;

figure 6 schematically shows a detail of the device of figure 5; And

Figure 1 shows the device according to the invention used with an oil recovery lubrication system.

The solution proposed according to the present invention, and which is illustrated by way of illustration in the attached figures, provides for the subdivision of the internal part of the classic two-stroke engine, i.e. the internal volume of the cylinder - head - volume of the crankcase into three distinct areas and separated from each other.

It is a "hot zone" which is in turn divided into two parts, an "upper hot zone" and a "lower hot zone" and finally a "cold zone".

Said "upper hot zone" is constituted by the volume physically delimited by the internal part of the cylinder head and by the piston head, where the washing, eventual fuel injection, combustion and expansion take place. Its volume is variable according to the reciprocating movement of the engine piston.

The "upper hot zone" communicates with the "lower hot zone", consisting of the lower part and a "separator" element which is an essential part of the invention and which will be described in greater detail below.

Depending on the type of connection between the piston and the mechanism for transforming the linear motion of the piston into rotary motion of the crankshaft, the "separator" assumes a different shape.

If the above connection is made by means of a connecting rod, the "separator" will be shaped as follows.

A sufficiently rigid membrane, equipped with suitable folds, to allow the oscillation of the connecting rod on the vertical plane. The membrane will be fixed to its periphery, to the cylinder, and to its central point to the connecting rod.

The membrane will be sufficiently rigid so as not to yield to the pressure variations that occur in the "lower hot zone" during the motion of the piston, which alternately sucks in the combustible mixture from the external environment and then compresses it, through the transfer channels , in the cylinder.

In the case of a particular shape of the piston, when this consists of a circular head and skirt with a central shaft fixed to the piston head, and which has a "cross head" at the other end to which the transformation members of the motion of the piston, the "separator" fixed to the cylinder, assumes the function of guiding the piston shaft, and the function of counteracting the lateral thrust against the cylinder walls caused by the mechanism for transforming the motion of the piston.

For this purpose, the "separator" will be hermetically fixed to the cylinder and will have a central hole in which the piston shaft will slide, which will be guided by a suitable system (for example, bushing or ball bush, all suitably lubricated from the outside), while it will at the end a suitable sealing system that will hermetically seal the volume of the "lower hot zone" from the "cold zone" which will be suitably lubricated for recovery.

In the solution according to the invention, the "lower hot zone" constitutes the suction and pressing pump which feeds with appropriate communication the "upper hot zone", where the burnt gas is washed, and the fluid is introduced for the new operating cycle. . The "lower hot zone" is equipped with a suitable valve (reed valve, rotating disk, etc.), which puts it in communication with the external environment during the suction phase. It is in communication by means of suitable transfer ports with the "upper hot zone".

The "cold zone" completely separated from the "lower hot zone" and from the "upper hot zone" in which the thermodynamic processes take place, can be perfectly lubricated with recovery oil, without causing fragmentation with the exhaust gases.

In some cases, the piston can be guided concentrically to the cylinder in such a way as not to make contact between its skirt and the cylinder wall, (or to make this happen in a reduced way), in such a way as to make lubrication between these surfaces.

Figures 1 to 3 show, without any limiting meaning, but only and solely illustrative, possible configurations that reproduce the principles described above, with specific types of crank mechanism.

In particular, Figure 1 illustrates a crank mechanism connecting rod 2 - crank 1, in which the effort is applied to the coupling between the skirt of the piston 3 and the contact with the cylinder (arrow A). The arrow B indicates the reaction force of the cylinder to the pressure of the piston skirt 3.

Finally, Figure 3 illustrates a solution for transforming the motion of the piston in which a disc 7 is provided, to which hydraulic cylinders 8 and an inclined disc 9 are integrally coupled, with integral pistons 10, which therefore requires a particular shape of the separator.

The separator element according to the invention takes different shapes according to the type of crank mechanism used.

The separator element can have the simple function of physically dividing the hot zone as previously defined "upper" and "lower", from the cold zone, or also the function of guiding the piston and supporting the thrust force caused by the inclination of the effort on the piston, to obtain the rotary motion.

In the case of the system illustrated in Figure 1, the separator element suitable for the transformation of the pendular and at the same time vertical motion of the connecting rod 2, must follow the oscillations, while keeping the hot and cold parts physically separate from each other.

An elastic bellows separator element 11 can be made (Figure 4), the external part of which is fixed to the cylinder 6, and the internal part to the connecting rod 2.

Between the two fixed parts of the separator element 11 there is provided a suitable succession of folds of the material which allow the pendular motion of the connecting rod 2 on the same vertical plane.

The supports 12 of the separator element are fixed on the cylinder 6 with a perfect seal.

The supports 13 are fixed on the connecting rod 2 with a perfect seal.

The folds of the separator element 11 must be such as to allow the vertical and pendular movements of the connecting rod 2, with the minimum variation in the volume of the "lower hot zone".

In the case of the transformation of the motion with the connecting rod 2 and crank 1 system (figure 1), the lubrication of the skirt of the piston 3, subjected to the lateral thrust, can take place with recovery of the oil, without mixing it with the combustible mixture.

The piston pin 3 can be lubricated with a "for life" lubricated support, or with suitable sintered materials.

The cold zone lubrication takes place with the typical forced lubrication used in four-stroke engines.

In the case of a motion transformation system as illustrated in Figures 2 and 3, a separator element must be provided which simultaneously performs the two functions of separation between the "hot" and "cold" areas, and to provide for the function of contrasting the forces. lateral thrust which, as seen in the case of the connecting rod 2 and crank 1 system, act on the piston 3 pushing the piston skirt against the cylinder 6, causing sliding friction.

As can be seen from figure 5, which shows a particular type of piston 3 equipped with a head 12, a rod 5 integral with it, which slides inside a fixed sleeve inside the cylinder 6, which sleeve as shown in the figure 6 in detail, it is made integral with the cylinder by being made with a continuous part of separation between the hot zone and the cold zone.

The separator element 31 must be fixed and, as mentioned, rigidly connected to the cylinder 6.

The separator element 31 is in this case constructed in such a way as to provide a sleeve 32 with recirculating balls (for example of the SKF LBR type) suitably sized and equipped with sealing at the separation end between the lower hot zone and the cold zone.

In this way, the piston 3 is guided concentrically with respect to the cylinder 6, so that, with an appropriate choice of the materials of the piston and the cylinder, and an appropriate choice of tolerances, it is possible to obtain a sliding with no contact between the cylinder and the piston, even if practically avoiding the leakage from the first hot zone to the second hot zone due to the resulting millesimal clearance.

In any case, in order to take into account the possible contact and in any case the sliding of the elastic bands for sealing the combustion compression, an oil recovery lubrication system thus constituted is provided.

The skirt of the piston, in this case cylindrical and without openings or recesses that interrupt the continuous circular profile, at least up to a certain height, as indicated in figure 8, brings to a suitable distance from the lower end a slot, of suitable dimensions, in which an elastic oil scraper ring takes place.

At a certain calculated height of the cylinder, in any case, below the lower edge of the discharge and transfer channels, two holes of suitable diameter are drilled in possibly diametrically opposite points, each communicating with a duct (internal or external as it is constructively convenient) which is connected to the oil pump lubrication circuit. The cylinder has no openings between the level of the holes and the level reached (below) by the scraper ring, unless it is necessary to bring oil to other positions. Operation is simple. When the piston motion brings the oil scraper ring in correspondence with the two cylinder holes in communication with the lubrication circuit, lubricant flows into the oil scraper compartment from the delivery oil hole, and oil flows out of the oil outlet hole already contained in the oil scraper compartment which is in excess due to the new oil which has come under pressure. The motion of the piston towards the P.M.I. distributes the oil along the cylinder leaving an infinitesimal trace of it, in particular within the grooves of cross grinding, which is common practice in the construction of cylinders. The compression rings, when the piston is at its P.M.I., come into contact with the area touched by the scraper when it was previously at the P.M.S., and collect the infinitesimal part of lubricant necessary for its own lubrication, but without this being able to pollute the products of combustion.

Summing up:

with the device according to the invention, the operation of the piston can be in the absence of friction, or with negligible friction, using special materials for the piston rings, and by graphitation of the piston skirt.

However, if you want to ensure beyond any doubt the lubrication of the piston skirt, you can use the solution that allows the lubrication of the piston skirt, and of the cylinder wall, and consequently of the compression rings, with the recovery system as well as described above.

As said, figure 8 shows an embodiment of this invention. The numerical reference 100 indicates the cylindrical skirt of the piston at the TDC, with the numerical reference 102 the groove at the lower end, with the numerical reference 103 the oil scraper, with the numerical references 104 and 105 the delivery and outlet holes of the oil connected to the lubrication circuit.

The "cold zone" where the movements of the elements constituting the motion transformation mechanism take place, whatever it is, as well as the sliding between the ball sleeve 32 (or bushing) and the piston shaft (figure 5), is preferably lubricated with oil under pressure, with the system known in the art.

The present invention has been described for illustrative, but not limitative purposes, according to its preferred embodiments, but it is understandable that variations and / or modifications may be made by experts in the art, without thereby departing from the scope of protection, as defined from the attached claims.

Claims (15)

CLAIMS 1. Device for obtaining a two-stroke engine with crankcase - pump separated from the system for transforming the alternating rectilinear motion into rotary motion of the crankshaft characterized by the fact that a subdivision or separation element is provided for the internal part of the engine, that is the internal volume of the head - cylinder complex - volume of the crankcase occupied by the mechanism for transforming the rectilinear motion of the piston into rotary motion, in two distinct and separate zones, respectively a hot zone and a cold zone, said hot zone being constituted by the volume physically delimited by the internal part of the head and the piston head, where the washing, possible fuel injection, combustion and expansion take place and by the lower part of the piston where the suction and compression of the washing fluid takes place and a cold zone , this being the lower area of a subdivision or separation element where the mechanism of crankshaft transformation. 2. Device according to claim 1, characterized in that said hot zone is divided into a first hot zone, the upper one, substantially constituted by the volume physically delimited by the internal part of the head and by the piston head, where the washing takes place, the possible fuel injection, combustion and expansion, and in a second hot zone, the lower one, delimited by the lower part of the piston and by said subdivision or separation element. 3. Device according to claim 2, characterized in that said first and second hot zones are in communication and have a complementary total volume, but variable with each other according to the position of the piston. 4. Device according to claim 2 or 3, characterized in that said "lower hot zone" which constitutes the pump casing, is in communication with the "upper hot zone" by means of transfer channels, and is in communication with the environment by means of the intake duct from which pure combustion air flows, if the fuel is supplied by injection, or mixed with fuel, if this is supplied by the carburetor. 5. Device according to one of the preceding claims, characterized in that in the case of a particular conformation of the piston, consisting of a circular head and skirt with a central shaft which carries the elements for the transformation of motion at the end, the cold zone is also the seat of the counter reaction force of the lateral thrust forces, which originate from the transformation of the motion itself. 6. Device according to one of the preceding claims, characterized in that said subdivision or separation element is constituted by an elastic bellows element, the external part of which is fixed to the cylinder, and the internal part to the connecting rod of the engine. 7. Device according to claim 6, characterized in that between the two fixed parts of the subdivision or separation element there is provided a succession of folds of the material which allow the pendular motion and on the same vertical plane, of the connecting rod. 8. Device according to claim 6 or 7, characterized in that there are provided supports of the subdivision or separation element fixed on the cylinder with a perfect seal, or movable supports, also with a perfect seal. 9. Device according to one of the preceding claims 1-5, characterized in that said subdivision or separation element consists of two parts with a sealed support which can be fixed or can slide tightly along the cylinder, said subdivision or separation element providing of the folds that allow an elasticity such as to compensate for the vertical sliding differences of the support parts and / or of the fixed or mobile supports. 10. Device according to one of the preceding claims 1 - 5, characterized in that said subdivision or separation element consists of two parts with a sealed support, said subdivision or separation element providing bends that allow an elasticity such as to compensate for the differences vertical sliding of the support parts and / or fixed or mobile supports. 11. Device according to claim 10, characterized in that said parts of the subdivision or separation element are constituted by shaped lamellae, of anti-friction material whose internal part, fixed to the supports, slides inside the external lamellae, fixed to the folds of said subdivision or separation element. Device according to one of the preceding claims 1 - 5, characterized in that said device consisting of an element fixed to the cylinder and thus made which constitutes a hermetic barrier between the lower hot zone and the cold zone, allows the piston to be guided concentrically with respect to the cylinder eliminating or reducing to a minimum the thrust of the piston skirt on the cylinder wall, obtaining the result of reducing or at least eliminating the need for lubrication between piston and cylinder, said piston being made with a head and with a suitable skirt extended only to the part necessary to cover the exhaust port in the movement phase from the P.M.I. at the TDC, said subdivision or separation element being constituted by a sleeve, said piston being provided with a rod suitably sized to be able to slide inside said sleeve. 13. Device according to claim 12, characterized in that said sleeve is constituted by a bushing or a ball sleeve which can be duly lubricated with recovery, provided with a suitable sealing system at the end which delimits the hot zone from the cold zone. 14. Device according to one of the preceding claims, characterized in that it provides a lubrication system which allows the oil recovery lubrication of the piston skirt, located in correspondence with the "lower hot zone" and consisting of a delivery hole and one for outlet located on the cylinder, below the transfer exhaust ports, and in communication with the pressure lubrication system, said two cylinder holes being constantly covered by the piston skirt, which at its lower end carries a slot in which an oil scraper ring, called ring, is placed in the position of the piston at TDC, being in correspondence with said two holes, which therefore allow pressurized oil to enter the oil scraper ring, which therefore occupies the annular volume in contact with the liner. 15. Device for obtaining a two-stroke engine with pump casing separated from the system for transforming the alternating rectilinear motion into rotary motion of the crankshaft and oil recovery lubrication, according to each of the preceding claims, substantially as illustrated and described.