RU2623334C2 - Method of heat cycle formation and device for its implementation - Google Patents

Abstract

FIELD: engines and pumps.

SUBSTANCE: displacement of the minimum and maximum volumes of the over-piston cavity relative to the top and bottom dead center (TDC and BDC) is provided, ensuring a combustion chamber volume to be close to a constant for the period of overlapping of the valves. At the same time, the over-piston cavity is reduced when the piston moves from TDC to BDC and increased when the piston passes through the BDC and this increase continues with its further movement to TDC. The volume of the combustion chamber, close to a constant one, is provided for the period of the combustion process of the working mixture and the supply of heat to the working element. To implement the method, the outer and inner pistons are coaxially arranged in the cylinder. The internal piston is hinged to the upper head of the center connecting rod, and the outer piston - to the two side connecting rods. Each of the connecting rods with its lower heads is mounted on the crank's centering plugs, the plugs for the side connecting rods are coaxial, and the plug for the central connecting rod is made between them with a displacement along the radius and the crank rotational angle against the rotation of the crankshaft. The efficiency of the engine is improved by increasing the filling ratio of the engine cylinders and improving the combustion process.

EFFECT: higher efficiency of engine operation.

5 cl, 5 dwg

Description

The invention relates to the field of engineering and can be used in internal combustion engines of general and special purpose and reciprocating compressors.

There is a method of functioning of internal combustion engines based on the classical thermodynamic cycles of Otto, Sabate-Trinkler, Diesel, which suggest a change in the phases of the gas distribution mechanism at the upper and lower dead points of the piston position, which leads to a low filling factor of the cylinder and a high coefficient of residual gases. This in turn determines the importance of power and economic indicators of engines [Popyk K.G., Sidorin K.I. Automobile and tractor engines, part 2. - M .: Higher school, 1976. - 280 p .; Arkhangelsky V.I. Car engines. - M .: Engineering, 1977. - 591 p .; Design and calculation of internal combustion engines: a textbook for universities / Ed. N.X. Dyachenko. - L .: Mechanical engineering, 1979. - 392 p .; Kolchin A.P., Demidov V.P. Calculation of automobile and tractor engines. - M.: Higher School, 1980. - 400 p.].

There is also an Atkinson cycle in which the intake valve is closed with a delay in the angle of rotation of the crankshaft on the compression stroke with an increase in the expansion stroke relative to the compression stroke due to a change in the geometrical radius of the crank by using an additional kinematic link in the crank mechanism and the cycle Miller, in which the intake valve closes significantly before the end of the intake cycle (or opens later than the beginning of this cycle) and is provided Orochony inlet "or substantially closes later than the end of this cycle and provides" truncated compression "with equal paths of movement of the piston on the compression and expansion strokes [http://ru.wikipedia.org/wiki/Atkinson; http://ru.wikipedia.org/wiki/Miller cycle].

The implementation of the Atkinson cycle is accompanied by the complexity of manufacturing the CABG in the presence of an additional kinematic link.

The benefit of increasing the thermal efficiency of the Miller cycle, unfortunately, is accompanied by a loss of peak output power for a given size (and weight) of the engine due to deterioration of cylinder filling.

In addition, the follow-up drive of the gas distribution mechanism in its classical design does not allow optimizing gas exchange processes and controlling the relations between the degrees of compression and expansion by varying the values of the recharging angles and free exhaust exhaust, as well as the valve overlap angles.

Internal combustion engines (ICE) are known based on a central or deaxial crank mechanism (CSM), in which the minimum and maximum volume of the supra-piston cavity is reached at the top and bottom dead centers (TDC and BDC), respectively, and its change is determined by the law of piston movement. At the same time, a short-term constancy of the volume of the combustion chamber is ensured at an angle of rotation of the crank of the crankshaft of ± 5 ° in the vicinity of TDC, which negatively affects the quality of the combustion process and mainly its decrease is caused by heat loss.

These losses are associated mainly with the extremely short - for a modern high-speed engine of less than a millisecond - the period during which it is necessary to ensure fuel combustion. Combustion conditions after the piston of the TDC passes the expansion stroke deteriorate. The volume of the combustion cavity increases, due to which the pressure and temperature of the gas sharply decrease, and the area of the cooling surfaces and, accordingly, the heat loss increase.

The difference between the degrees of compression and expansion can only be introduced by controlling the gas distribution phases, mainly due to an increase in the angle of recharge of the cylinders, which reduces the amount of working fluid in the engine cylinders, and, consequently, the power of the engine as a whole.

The energy supply of the burned fuel to the working body is carried out not at the beginning of the stroke of the working stroke, but in its middle and even at the end, which negatively affects the formation of torque [Popyk KG, Sidorin KI Automobile and tractor engines, part 2. - M .: Higher school, 1976. - 280 p .; Arkhangelsky V.I. Car engines. - M .: Engineering, 1977. - 591 p .; Design and calculation of internal combustion engines: a textbook for universities / Ed. N.X. Dyachenko. - L .: Mechanical Engineering, 1979. -392 p .; Kolchin A.I., Demidov V.P. Calculation of automobile and tractor engines. - M.: Higher School, 1980. - 400 p.].

A device for operating an internal combustion engine with overexpansion is also known [patent RU 2382889, 02.27.2010]. The proposed technical solution allows to solve a number of problems of the classic ICEs described above, but it itself has a significant drawback - it is its implementation complexity, increase in overall mass characteristics and structural complexity of the cylinder head.

These shortcomings can be eliminated when forming the thermodynamic cycle of the internal combustion engine, in which the intake valve is closed with a delay in the angle of rotation of the crankshaft at the compression stroke, preliminary opening of the exhaust valve at the expansion stroke and their overlap at the end of the exhaust stroke and the beginning of the intake stroke the values of the minimum and maximum volumes of the supra-piston cavity relative to the upper and lower dead points, respectively, in the direction of rotation of the crank of the crankshaft and ensure the volume of the combustion chamber is close to constant for the period of valve overlap, the piston cavity is reduced during the movement of pistons coaxially placed in each other from the top dead center to the bottom, which move relative to each other and the cylinder, with an offset relative to the top and bottom dead points crank of the crankshaft, and increase it when the pistons pass the bottom dead center and with their further movement to the top dead center, and also provide a volume of the combustion chamber close to constant over the period d the process of combustion of the working mixture and the supply of heat to the working body, and at the same time form the effect of the pressure of the working fluid on the area of the pistons.

The implementation of the proposed thermodynamic cycle can be achieved by a device representing a crank mechanism consisting of fixed parts: a crankcase and at least one cylinder with a head, made as a single unit or interconnected by means of anchor joints, through a gasket, and moving parts: cranked a shaft pivotally mounted in the crankcase, a connecting rod, pivotally mounted on the crank pin of the crankshaft with its crank head and, through the finger, with its piston head with a piston, which with rings is placed in the cylinder cavity, while in the cylinder two pistons are placed coaxially, the outer one in contact with the cylinder and the inner one placed in the cylindrical cavity of the outer piston made along its axis, and each of the pistons is in contact with the corresponding cylindrical forming by means of rings mounted in grooves made on the sealing part of the outer and inner pistons, on the bottom of each of the pistons, from diametrically opposite sides, tides are made in the form of circles with holes for the piston fingers, by means of which the internal piston is pivotally connected to the upper head of the central connecting rod, and the external piston with two side connecting rods so that each of the side connecting rods with its upper heads is cantilevered with the tide of the external piston with a separate finger, and each of the connecting rods with their lower heads with covers and fasteners, they are pivotally mounted on the landing necks of the crank, while the necks under the side connecting rods are made coaxially in the form of tides to adjacent cheeks m and neck under the central rod is formed therebetween, with an offset of a start and crank angle against the rotation stroke of the crankshaft.

As an additional hinge connection between the pistons and connecting rods, a solution can be realized that the shoulders with a cylindrical working surface, a concentric bore for the piston pin, with a radius equal to the radius, are aligned with the upper head of the middle connecting rod, on both its sides and on the outside of the side connecting rods tides made in the form of semicircles with holes for piston fingers on the bottom of the pistons, with diametrically opposite sides and a width equal to the thickness of the corresponding tides.

Or that the middle piston is connected to the central connecting rod by means of a spherical connection made in the form of a hemispherical recess on the bottom of the piston, in cooperation with which is a ball made on the end of the central connecting rod and held in it by two half rings with hemispherical recesses attached to the bottom of the piston.

It may be that at the bottom of the cylindrical recess of the outer piston and on the plane of the bottom generatrix of the inner piston, grooves for sealing rings, for example, of fluoroplastic, are made coaxially with them.

In FIG. 1 shows graphs of changes in the supra-piston cavity of the classic central and proposed CABG, in FIG. 2 - pie charts of the gas distribution phases of the internal combustion engine based on the classic central a) and proposed b) KShM, in FIG. 3 is a comparison of the indicator diagrams of the compression and expansion cycles of the internal combustion engine based on the classic central and proposed KShM, in FIG. 4 is a general view of a cshm and its sections, in FIG. 5 is a general view of the 3D model of the proposed KShM and its section.

The essence of the proposed method of functioning of an internal combustion engine that implements the claimed thermodynamic cycle can be clarified on the basis of a comparative analysis of the graphs of changes in the supra-piston cavity of the classic central and proposed crank mesh, shown in FIG. 1, pie charts of the gas distribution phases of the internal combustion engine based on the classic central a) and proposed b) KShM shown in FIG. 2, indicator diagrams of the compression and expansion strokes of the internal combustion engine based on the classic central and proposed KShM shown in FIG. 3.

From the analysis of the graphs of the changes in the supra-piston cavity of the classical central and proposed CABG, shown in FIG. 1, it follows that there is a near-constant value of the volume of the combustion chamber V _c at an angle of rotation of the crank of the crankshaft by an angle of more than 20 ° in comparison with 10 ° of a classical ICE. This allows you to better clean the combustion chamber when the valves overlap between the exhaust and intake strokes, and most importantly, increase the thermal efficiency and efficiency of the combustion process of the working mixture, heat supply to the working body and the influence of the working fluid pressure on the piston area at the beginning of the expansion stroke.

Approximately at an angle of 10 °, the maximum value of the cylinder working volume V _{h is} constant, which improves the process of filling the cylinder with a working fluid (recharging process). And further, when the piston moves to the TDC, the volume of the supra-piston cavity increases by 18% in comparison with the classical ICE, and consequently, the pressure and temperature of the working fluid at the compression stroke decrease, which leads to a decrease in the heat transfer intensity between the working fluid and the parts of the crankshaft.

On the expansion stroke, there is a decrease in the volume of the supra-piston cavity by 12.5%. This leads to an increase in pressure and temperature of the working fluid, and, consequently, a more efficient and lengthy process of torque formation.

The analysis of the gas phase diagrams shown in FIG. 2 fully confirms these conclusions, and also allows us to conclude that it is possible to introduce a significant difference between the degrees of compression ε _c and expansion ε _p in order to achieve the results of the Atkinson-Miller cycles, while eliminating their drawbacks.

The analysis of the indicator diagrams of the compression and expansion cycles shown in FIG. 3, (qualitative picture) allows us to claim a twofold increase in the area of the figure enclosed between the compression and expansion curves in the internal combustion engine based on the classical central and proposed KShM. This area is equivalent to the work cycle performed.

To implement the proposed method for forming a thermodynamic cycle, the internal combustion engine should be made in the form of the device shown in FIG. 4 and including crankcase 1, cylinder 2, crankshaft 3, pivotally mounted in crankcase 1, while two pistons are coaxially placed in cylinder 2, outer 4 in contact with cylinder 2, and inner 5 placed in the cylindrical cavity of the outer piston 4, made along its axis, and each of the pistons is in contact with the corresponding cylindrical generatrix by means of rings mounted in grooves made on the sealing part of the outer 4 and inner 5 pistons.

On the bottom of each of the pistons, from diametrically opposite sides, semicircular tides are made with holes for the piston pins 6 and 7, through which the internal piston 5 is pivotally connected to the upper head of the central connecting rod 8, and the external piston 4 with two side connecting rods 9. Moreover, each of the side connecting rods 9 with its upper heads is cantilevered to the tide of the external piston 4 with a separate finger 7.

Each of the connecting rods with their lower heads with covers and fastening elements are pivotally mounted on the crank landing necks, while the necks under the side connecting rods (lateral necks) are made coaxially in the form of tides to adjacent cheeks, and the neck under the central connecting rod (central neck) is made between them with offset offset and the angle of rotation of the crank against the course of rotation of the crankshaft.

As an additional hinge connection between the pistons 4 and 5 and the connecting rods 8 and 9, cylindrical working surfaces, made in the form of shoulders coaxially with the upper head of the middle connecting rod 8, on both sides and on the outside of the side connecting rods 9, concentric with the holes for the piston fingers 6 and 7, with a radius equal to the radius of the tides, made in the form of semicircles with holes for the piston pins 6 and 7 on the bottom of the pistons 4 and 5, with diametrically opposite sides and a width equal to the thickness of the corresponding tides, and interacting with the surface of the cylindrical generators of these tides.

The proposed device operates as follows. When the outer piston 4 is located at the TDC, the inner piston 5 is on the approach to the TDC due to the angular displacement of the central neck of the crank of the crankshaft 3. With a further rotation of the crank, the outer piston 4 begins to move down to the BDC, and the inner piston 5 continues to move to the TDC. In this case, the increase in the volume of the combustion chamber during the movement of the outer piston 4 is compensated by the volume of the body of the inner piston 5 moving to the upper dead center, determined by the angular position and the outreach of the central neck of the crankshaft 3. Such compensation will be observed during the angular movement of the crank by an angle of more than 20 °.

With a further rotation of the crank and movement of the pistons to the BDC, the internal piston 5 will be higher than the external piston 4 and the volume of the over-piston cavity will decrease by the volume of the internal piston. Such a reduction in the supra-piston cavity will be observed until the external piston 4 approaches the BDC.

With a further rotation of the crank and the movement of the outer piston 4 to the upper dead center, the inner piston 5 will move to its BDC, moving in the cavity of the cylinder made along the axis of the outer piston 4. In this case, the supra-piston cavity will be constant at an angle of rotation of the crank of the crankshaft 3 of approximately 10 ° , which helps to fill the cylinder with a working fluid.

With a further rotation of the crank and the movement of the pistons to TDC, the inner piston 5 will be located inside the cylinder of the outer piston 4, moving downward, and the volume of the over-piston cavity will increase by the amount of free space from the inner piston 5. Such an increase in the over-piston cavity will be observed until the external piston 4 approaches the TDC.

The ignition timing or fuel injection angle can be approximately 5-10 ° until the outer piston 4 approaches the TDC, which is sufficient for mixture formation, ignition and formation of the flame front. And then the combustion process with the practical constancy of the volume of the combustion chamber, which will be more than 20 ° of the angle of rotation of the crank of the crankshaft 3 after the passage of the TDC. With these ratios of angles, the loss of back pressure is reduced and the supply of heat to the working body and the effectiveness of the pressure of the working fluid on the piston area are increased.

The effect of using the invention is that the engine efficiency is increased by increasing the fill factor of the engine cylinders and improving the combustion process. There is a gain from increasing the thermal efficiency of the cycle, and, consequently, an increase in economic and environmental indicators with a low percentage of emissions of harmful substances, especially nitric oxide. In addition, the magnitude of the torque increases significantly.

Thus, the above information indicates that when using the invention the following set of conditions:

- the invention in its implementation is intended for use in the design of piston engines;

- for the invention in the form as it is characterized, the possibility of its implementation using the devices described above or known prior to the priority date is confirmed;

- the invention in its implementation is able to ensure the achievement of a technical result.

Therefore, the invention meets the requirement of "industrial applicability".

Information sources

1. Popyk K.G., Sidorin K.I. Automobile and tractor engines, part 2. - M .: Higher school, 1976. - 280 p.

2. Arkhangelsky V.I. Car engines. - M.: Mechanical Engineering, 1977 .-- 591 p.

3. Design and calculation of internal combustion engines: a textbook for universities / Ed. N.X. Dyachenko. - L .: Mechanical Engineering, 1979. - 392 p.

4. Kolchin A.I., Demidov V.P. Calculation of automobile and tractor engines. - M .: Higher school, 1980 - 400 p.

5.http: //ru.wikipedia.org/wiki/Atkinson.

6.http: //ru.wikipedia.org/wiki/Miller cycle.

Claims (5)

1. The method of forming the thermodynamic cycle of an internal combustion engine, in which the intake valve closes with a delay in the angle of rotation of the crankshaft at the compression stroke, preliminary opening of the exhaust valve at the expansion stroke and their overlap at the end of the exhaust stroke and the beginning of the intake stroke, characterized in that provide a shift in the values of the minimum and maximum volumes of the supra-piston cavity relative to the upper and lower dead points, respectively, in the direction of rotation of the crank of the crankshaft and about provide the volume of the combustion chamber close to constant for the period of valve overlap, reduce the piston cavity during the movement of pistons coaxially placed in each other, from the top dead center to the bottom, which move relative to each other and the cylinder, with a shift relative to the top and bottom dead points of the crankshaft shaft, and increase it when the pistons pass the bottom dead center and when they move further to the top dead center, and also provide a volume of the combustion chamber close to constant by the period of the combustion process of the working mixture and the supply of heat to the working body, and at the same time they are affected by the pressure of the working fluid on the area of the pistons. 2. A device for implementing the method according to claim 1, which is a crank mechanism consisting of fixed parts: a crankcase and at least one cylinder with a head, made in the form of a single unit or interconnected by means of anchor connections through a gasket, and moving parts: crankshaft pivotally mounted in the crankcase, a connecting rod pivotally mounted on the crank pin of the crankshaft with its crank head and, through the finger, with its piston head connected to the piston, which is placed with the rings a cylinder cavity, characterized in that two pistons are coaxially placed in the cylinder: an external piston in contact with the cylinder and an internal piston located in its cylindrical cavity on its axis, and each of the pistons is in contact with a corresponding cylindrical generatrix by means of rings mounted in grooves made on the sealing part of the outer and inner pistons, tides in the form of semicircles with holes for p piston fingers, by means of which the internal piston is pivotally connected to the upper head of the central connecting rod, and the external piston with two side connecting rods in such a way that each of the side connecting rods with its upper heads is cantilevered to the tide of the external piston with a separate finger, and each of the connecting rods with its lower heads with lids and fasteners are pivotally mounted on the landing necks of the crank, while the necks under the side connecting rods are made coaxially in the form of tides to adjacent cheeks, and the neck under the central connecting rod Execute between the offset of the flight and the angle of rotation of the crank anti-rotation stroke of the crankshaft. 3. The device according to claim 2, characterized in that the shoulders with a cylindrical working surface, a concentric hole for the piston pin, with a radius equal to the radius of the tides made coaxially with the upper head of the middle connecting rod, on both sides and on the outside of the side connecting rods in the form of semicircles with holes for piston fingers on the bottom of the pistons, with diametrically opposite sides and a width equal to the thickness of the corresponding tides. 4. The device according to p. 2, characterized in that the inner piston is connected to the central connecting rod through a spherical connection made in the form of a hemispherical recess on the bottom of the piston, in cooperation with which is a ball made on the end of the central connecting rod and held in it by two half rings with hemispherical recesses attached to the bottom of the piston. 5. The device according to p. 2, characterized in that at the bottom of the cylindrical recesses of the outer piston and on the plane of the bottom generatrix of the inner piston, grooves for sealing rings, for example, of fluoroplastic, are made coaxially with them.

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