Combined heat engine

Abstract

FIELD: engine building.SUBSTANCE: combined heat engine contains a housing, first and second crankshafts (2, 19) located inside, having a kinematic connection. The second crankshaft (19) rotates twice as slow as the first (2). On the crankshafts (2, 19) there is a cold cylinder (7, 30), designed with the possibility of heat removal, and two working cylinders (3, 5, 20, 21), designed with the possibility of operation in opposite modes relative to each other and which are convertible during operation. Each working cylinder (3, 5, 20, 21) includes an inlet (12, 16, 24, 27), outlet (13, 17, 25, 28) valve and a valve (11, 15, 26, 29) for disconnecting from the regenerator (10, 33), thus, part of the time it operates in the four-stroke ICE mode, and part of the time as a hot cylinder of an alpha Stirling type engine.EFFECT: increased efficiency and increased engine power, reduced thermal emissions into the environment and reduced engine noise levels.1 cl, 1 dwg

Description

[0001] The invention relates to the field of mechanical engineering, in particular to engine building, and can be used in transport and energy.

[0002] A widely known prior art engine is the A-type Stirling engine (see G. Walker, "Stirling Engines" M. Mechanical Engineering, 1985, pp. 85-88), comprising a crankcase with hot and cold cylinders mounted thereon, arranged at an angle of 90 degrees in a V-shaped arrangement of cylinders and operating on a single crankshaft crank (with an in-line arrangement of cylinders, there is a phase shift of 90 degrees of crankshaft rotation). The working piston, located in the hot cylinder, forms an expansion cavity with its walls, while the displacement piston, located in the cold cylinder, forms a compression cavity with its walls. The hot expansion cavity is connected to the cold compression cavity via a heater, regenerator, and cooler. The disadvantage of this analogue is that the heating of the cylinder walls occurs from the outside, not from the inside, which increases the requirement for the heat resistance of the material of the cylinder walls and the heater.External heat input results in significant heat losses. The practical efficiency of such engines typically does not exceed 20-40%. A significant portion of the thermal energy from fuel combustion is released into the environment as heat loss, producing no useful work. Regulating changes in the power and speed of the output shaft of such an engine requires a complex control system.

[0003] A four-stroke piston engine is widely known, for example, one operating on the Otto or Diesel cycle (Alekseev V.P., Voronin V.F., Grekhov L.V. et al. "Internal Combustion Engines. The Design and Operation of Piston and Combined Engines." 4th ed., revised and enlarged. Moscow: Mashinostroenie, 1990.), in which the working process in each cylinder is carried out in two crankshaft revolutions, that is, in four piston strokes (strokes), containing a housing, cylinders, pistons, a distribution mechanism, a fuel-air mixture supply system, and an exhaust gas removal system. The disadvantage of this analogue is that for normal engine operation, heat must be removed from the walls of the working cylinders, and this removed heat is not converted into useful work, and part of the thermochemical energy of fuel combustion is released into the environment along with the exhaust gases. The practical efficiency of such engines is 25-45%.A significant portion of the thermal energy from fuel combustion is released into the environment in the form of heat losses without performing useful work.

[0004] The six-stroke internal combustion engine, in which the complete operating cycle occurs in six strokes, is also widely known. (Sobolenko A.N. "Thermodynamic efficiency of the generalized theoretical cycle of a six-stroke internal combustion engine" / / , as well as Zhukov V.A., Yamanin A.I., Melnik O.V. "Engines with a six-stroke working cycle: operating order and crankshaft diagrams" / / Bulletin of the Admiral S.O. Makarov State University of Maritime and Inland Shipping. - 2018. - No. 6 (52)) An engine of this type operates on the Otto or Diesel cycle for the first four strokes, and then cooled air is supplied to the cylinder on the fifth stroke, due to which additional cooling of the cylinder walls occurs, while the heated air expands, thereby exerting slight pressure on the piston.The disadvantage of this alternative is that, in order for the cooled air supplied to the cylinder to exert high pressure on the piston, thereby increasing the engine's useful work, it is necessary to inject air into the cylinder under high pressure. Since air is expelled from the cylinder through the exhaust system during the sixth stroke, the subsequent injection of cool air under pressure requires significant work to compress and cool it, which significantly reduces engine efficiency.

[0005] A five-stroke internal combustion engine equipped with "fifth-stroke cylinders" serving for additional expansion of exhaust gases, which perform work in the process, is widely known. (Ter-Mkrtichyan G.G. "Progressive Designs and Operating Processes of Internal Combustion Engines." Study Guide. Moscow: Infra-Engineering, 2024. ISBN 978-5-9729-1802-7). The book has a section devoted to five-stroke engines: the concepts (including developments by Ilmor Engineering and Gerhard Schmitz), implementation mechanisms and prospects of such cycles are considered, as well as Berdnikov A.A., Nagaitsev D.S., Titkov N.V. Article "Internal Combustion Engine with an Unconventional Working Cycle". Published in the journal "Fundamental Research" (2017, No. 4). The paper analyzes the potential of cycles with additional strokes, including a five-stroke cycle, through heat recovery and continued expansion of the working fluid. For every two conventional cylinders, there is one "fifth-stroke cylinder."The crankshaft is shaped so that the regular pistons move in phase with each other, while the additional piston moves out of phase with both. The timing system is designed so that compression and exhaust are alternated in the regular cylinders. Thus, for every upward stroke of the regular piston, the additional piston moves downward, and, furthermore, exhaust occurs in one or the other regular cylinder. The disadvantage of this design is that it does not utilize the thermal energy of the working cylinder walls themselves, nor the walls of the fifth-stroke cylinders, but only the expansion energy of the hot exhaust gases.

[0006] Also known is the device "FOUR-STROKE DIESEL CONVERTIBLE INTO AN ALPHA VARIANT STIRLING ENGINE." Invention application 2009115136 / 06 dated April 20, 2009. Author: Vil Moiseevich Kapitansky. The device is a four-stroke diesel engine equipped with a number of devices that convert it into a convertible engine, operating either as a diesel or as an alpha Stirling engine with air as a working fluid, with switching from the stopped position. This device uses a similar technical solution, namely, using the same cylinder as an internal combustion engine cylinder and also as a Stirling engine cylinder. The disadvantage of this analogue is that it does not have the ability to switch from the engine operating on the Diesel cycle to the engine operating on the Stirling cycle during operation, but only from the stopped position.Therefore, this analogue does not have the ability to use the heat of the cylinder walls heated after operation in the ICE mode when operating in the Alpha Stirling mode.

[0007] The closest device for the same purpose to the claimed device in terms of a combination of features is the device presented in the patent application F02G 5 / 04 (1995.01 Application: 92009115 / 06, 11 / 30 / 1992) Application publication date: 08 / 27 / 1996 authors Kukis V.S., Orekhov S.V., "A power plant including a compressor diesel connected by exhaust manifolds to the head of a Stirling engine contains a Stirling engine made integral with the compressor." This device uses a similar technical solution, namely the use of a heat engine operating on the Stirling cycle to convert the heat losses of an internal combustion engine into useful work, thereby increasing the efficiency of the power plant. The disadvantage of this device is that it does not use the thermal energy of the hot cylinder walls of the internal combustion engine, but only the thermal energy of the exhaust gases.At high engine speeds, the exhaust gases will quickly pass through the heat exchanger at high speed and transfer less heat to the walls of the hot cylinder or the Stirling engine heater, which, for best engine operation, must be heated as much as possible. The hotter they are, the less they are able to capture heat from the exhaust gases. With this technical solution, a large amount of thermal energy from the exhaust gases will be released into the environment without performing useful work.

[0008] The purpose of the invention is to create a combined heat engine capable of converting a greater amount of fuel combustion energy into useful work than one single heat engine, such as an internal combustion engine, through the use of a combination of heat engines operating on a single output shaft, thereby increasing the efficiency and power of the entire combined heat engine in relation to an internal combustion engine.

[0009] The technical result is increased internal combustion engine efficiency and increased engine power. Reduced thermal emissions into the environment. Reduced engine noise.

[0010] This technical result is achieved by the proposed combined heat engine, which combines a well-known four-stroke internal combustion engine with two other heat engines, all working on a common output shaft. Each of these two heat engines operates from the temperature difference between the hot expansion chamber and the cold compression chamber, using the Stirling cycle. The first heat engine utilizes the heat from the walls of the engine's working cylinders, while the second utilizes the heat from the exhaust gases. The combined heat engine comprises a housing containing two crankshafts with a kinematic linkage. The fast crankshaft rotates twice as fast as the slow crankshaft. The fast crankshaft contains two working cylinders of equal volume, each containing pistons, intake and exhaust valves, a timing gear, a fuel-air mixture supply system, and other systems that enable the engine to operate in four-stroke internal combustion engine mode.To increase engine efficiency and power by converting cylinder wall heat loss into useful work, two working cylinders are designed as convertible cylinders. The valve train is designed to allow each cylinder to operate for four strokes in internal combustion engine mode, followed by four strokes as the hot cylinder of an Alpha Stirling engine. During these four strokes, the cylinder walls and the piston located within form an expansion chamber. Also located on the high-speed shaft is a single cold cylinder of similar volume to the converted cylinder. It is designed to dissipate heat from the cylinder, similar to the cold cylinder of an Alpha Stirling engine. It is connected by lines in series with a cooler and regenerator, from which the common line splits into two, leading to each converted cylinder. The pistons of the converted cylinders reach top dead center (TDC) simultaneously.The walls of the cold cylinder, together with the piston located within, form a compression chamber. The piston connecting rods are mounted on a common high-speed crankshaft so that changes in the expansion chamber volume lead changes in the compression chamber volume by a phase angle of approximately 90 degrees. All three cylinders form a single cylinder group located on the high-speed crankshaft, operating together and sharing a common working fluid. A valve is located in the head of each convertible cylinder, which serves to isolate the internal cylinder chamber from the regenerator, cooler, and cold cylinder chamber. The two convertible cylinders in this group operate in different modes relative to each other, switching between which occurs at TDC after every four strokes.Thus, with one of the expansion chambers—namely, the convertible cylinder of the group that does not operate in ICE mode—thanks to the sequential opening of the valves leading to the regenerator, the compression chamber forms an Alpha Stirling-type heat engine. Heating of the hot cylinder walls occurs not from the outside, but from the inside, due to the cylinder having previously operated in ICE mode for four strokes. To increase engine efficiency and power by converting exhaust heat loss into useful work, two convertible cylinders of equal volume, with pistons located inside them, are located on the slow-speed crankshaft. The volume of this convertible cylinder is larger than the volume of the convertible cylinder on the fast-speed crankshaft. The valve train is designed so that each of them operates as an exhaust expansion cylinder for two strokes, then operates as the hot cylinder of an Alpha Stirling-type engine for two strokes.During these two strokes, the cylinder walls and the piston located within form an expansion chamber. The pistons of the convertible cylinders on the slow-speed shaft reach TDC simultaneously. On the slow-speed shaft, there is one cold cylinder of similar volume to the convertible cylinder on this shaft. This cylinder is designed to dissipate heat from the cylinder and is connected in series by lines to the cooler and regenerator, from which the common line branches into two lines leading to each convertible cylinder on the slow-speed shaft. The walls of the cold cylinder and its piston form a compression chamber. All three cylinders on this shaft form the second group of cylinders in the combined heat engine, working together and using the same working fluid. The piston connecting rods are secured to the common slow-speed crankshaft so that changes in the expansion chamber volume lead changes in the compression chamber volume, at a phase angle of approximately 90 degrees.The exhaust valve of each convertible cylinder on the high-speed crankshaft is connected by a pipe to the intake valve of the corresponding convertible cylinder on the low-speed crankshaft. The intake valve is located in the cylinder head, which also contains an exhaust valve connecting the cylinder chamber to the atmosphere and a valve disconnecting the cylinder chamber from the line leading to the regenerator of the cylinder group on the low-speed crankshaft. The high-speed and low-speed crankshafts are installed relative to each other such that the piston of the convertible cylinder on the low-speed crankshaft reaches TDC when the piston of the corresponding convertible cylinder on the high-speed crankshaft, connected to it by a pipe, is at bottom dead center (BDC), before the exhaust stroke of the internal combustion engine. Thus, the exhaust actually acts as a bypass, moving gases into the larger cylinder, which leads to their expansion, which performs additional work. Then, on the second exhaust stroke, the gases are expelled by the piston into the atmosphere.During the third intake stroke, this cylinder receives working fluid from the compression chamber of the cylinder group on the slow shaft, and it operates as the hot cylinder of an Alpha Stirling engine. During the fourth exhaust stroke, the working fluid returns to the compression chamber. The two convertible cylinders of this group operate in different modes relative to each other, switching between them at TDC after every two strokes. Thus, with one of the expansion chambers of the cylinder group located on the slow shaft—namely, the cylinder that does not perform work due to the expansion of hot exhaust gases—thanks to the sequential opening of valves connected to the regenerator, the compression chamber forms an Alpha Stirling heat engine, where the walls of the hot cylinder are heated not from the outside, but from the inside, due to the hot exhaust gases previously expanding within the cylinder.

[0011] With this combination of heat engines, fuel is burned only during internal combustion engine operation, and no additional fuel is required for the other two heat engines. Moreover, in the proposed invention, the cylinder walls are heated from the inside, not the outside, and are then immediately cooled by the working fluid, which avoids losses associated with thermal conductivity of the cylinder walls. Reducing the temperature of cold cylinders or increasing the wall temperature of convertible cylinders, for example, by using fuel with a higher octane number, will increase the efficiency of the Alpha Stirling engine, and consequently the overall efficiency of the entire combined heat engine. Any gas can be used as the working fluid in these Alpha Stirling engines, preferably under high pressure to increase efficiency, ensuring safe engine operation.In a Stirling engine, after the piston-cylinder head operation, a certain amount of working fluid under high pressure will remain in the gap between the piston and the cylinder head after the valve leading to the regenerator closes. To eliminate the consequences of this phenomenon, if necessary, the cylinder heads of such engines will have an appropriate technical solution. For example, when using exhaust gases as the working fluid, residual working fluid can be removed during the intake stroke through an additional exhaust purge valve, while clean air must be supplied under pressure. If compressed air is used as the working fluid, then during the intake stroke, excess air must simply be removed from the cylinder if its amount in the gap exceeds that required for the internal combustion engine.A combustible gas, such as methane or hydrogen, can be used as the working fluid, further increasing the efficiency of the hybrid engine. The residual gas in the gap between the piston and cylinder head can be used as fuel. Since significantly more heat is converted into useful work, thermal emissions are reduced. And because the exhaust gases are not immediately released into the environment but first enter the larger expansion cylinders, the noise level of the hybrid engine will be lower than that of a conventional internal combustion engine.

[0012] The proposed technical solution is shown in Fig.

[0013] The claimed combined heat engine comprises a housing 1, inside which are a fast crankshaft (2) and a slow crankshaft 19, which has a kinematic connection 34 with it, rotating twice as slowly. On the fast crankshaft, two convertible cylinders 3.5 of the same volume are located with pistons 4 and 6 inside, reaching TDC simultaneously. As well as one cold cylinder 7, having a design adapted to remove heat from the cylinder, containing a piston 8 inside. All three cylinders 3.5, 7 form a group of cylinders on the fast crankshaft, working together and using a common working fluid. The cold cylinder 7 is sequentially connected by lines to a cooler 9, a regenerator 10, from which the common line diverges into two, leading to each convertible cylinder of the fast crankshaft 3.5.The head of each convertible cylinder on this shaft contains elements of the fuel-air mixture ignition system or other devices necessary for the cylinder's operation in the internal combustion engine mode, but in Fig. , to simplify the understanding of the combined heat engine's operating principle, only the valves are shown, since only their operation is important for understanding the operating principle. The head of convertible cylinder 3.5 contains valve 11.15, which serves to isolate the internal cavity of the cylinder from the line leading to regenerator 10, an inlet valve 12.16 connected to the fuel-air mixture supply system, and an exhaust valve 13.17. On the slow crankshaft 19, two convertible cylinders 20.21 of the same volume are located with pistons 22.23 located inside, reaching TDC simultaneously.Also, a cold cylinder 30, having a design adapted to remove heat from the cylinder, with a piston 31 inside, connected in series by lines to a cooler 32, a regenerator 33, from which the common line diverges into two, leading to each convertible cylinder of the slow crankshaft 20,21. All three cylinders 20,21,30 form a group of engine cylinders on the slow crankshaft, working together and using a common working fluid. The head of the convertible cylinder 20,21 contains an intake valve 24,27 connected by a pipe 14,18 to an exhaust valve 13,17 of cylinder 3,5. Also, an exhaust valve 25,28 is connected to the environment. Also, valve 26.29 serves to disconnect the internal cavity of the cylinder from the line leading to regenerator 33. The piston connecting rods are fixed on each crankshaft so that changes in the volume of the expansion cavities lead changes in the volume of the compression cavity in phase by an angle close to 90 degrees.

[0014] The combined heat engine works as follows.

[0015] During the initial start, one of the two convertible cylinders of the fast crankshaft 2, for example, cylinder 5, begins to operate in the internal combustion engine mode when piston 6 is at TDC. Valve 15 is closed, and four internal combustion engine strokes occur in the working convertible cylinder 5. During the intake, valve 16 is open, all valves are closed during the compression and power strokes, and valve 17 is open during the exhaust. During the four operating strokes of convertible cylinder 5 in the internal combustion engine mode, only valve 11 in the other convertible cylinder 3 is open, and the working fluid from the cold cylinder 7 moves through cooler 9, regenerator 10 into the convertible cylinder 3 and back. Cylinders 3 and 7 operate as a heat engine (Alpha Stirling engine) for four strokes.On the fifth stroke, valve 11 of cylinder 3 closes and intake valve 12 opens, and cylinder 3 operates in ICE mode for the next four strokes. Meanwhile, valve 15 in cylinder 5 is open, and now, along with cold cylinder 7, it operates as an Alpha Stirling engine for the next four strokes. The cycle on the fast crankshaft repeats every eight strokes. After the third stroke of ICE operation of cylinder 5, piston 6 is at BDC before the exhaust stroke, and piston 23 of cylinder 21 is at TDC. At this moment, the exhaust valve 17 and the inlet valve 27 open and the exhaust gases through the pipe 18 on the fourth stroke of the convertible cylinder 5 move into the convertible cylinder 21. Since the rotation speed of the slow crankshaft 19 is two times less, the piston 23 bypasses the gases in half a stroke, after which the valve 27 closes and for the remaining half stroke the piston 23 moves downwards due to the expansion of the exhaust gases.During the second stroke, piston 23 expels exhaust gases from the cylinder into the surrounding environment through exhaust valve 28. While these two strokes occur in converted cylinder 21, only valve 26 is open in converted cylinder 20, through which the working fluid enters. Converted cylinder 20, through regenerator 33 and cooler 32, operates for two strokes as an alpha Stirling heat engine, along with the cold cylinder 30. During the third and fourth strokes, only valve 29 is open in converted cylinder 21, and cylinders 21 and 30 operate as alpha Stirling heat engines. On the third stroke, inlet valve 24 is open in convertible cylinder 20 and piston 22 draws exhaust gases through pipe 14 from convertible cylinder 3 for half of the stroke, then inlet valve 24 closes and piston 22 moves downwards for the remaining half of the stroke due to the expansion of exhaust gases.On the fourth stroke, piston 22 forces exhaust gases out of the cylinder into the environment through exhaust valve 25. The cycle on a slow crankshaft is repeated every four strokes.

Claims

A combined heat engine comprising a housing, a first crankshaft located inside, on which working cylinders are mounted, configured to heat up during engine operation and requiring cooling, characterized in that it comprises a second crankshaft, wherein the first crankshaft is fast, and the second, having a kinematic connection with the first, is slow with the ability to rotate twice as slowly, on the fast crankshaft there is a cold cylinder configured to remove heat, and two working cylinders configured to operate in opposite modes relative to each other and being convertible during operation, wherein the connecting rods of the working cylinders are ahead in phase of the connecting rod of the cold cylinder by an angle close to 90°, each working cylinder includes an intake valve, an exhaust valve and a valve for shutting off from the regenerator, thus, part of the time it operates in the four-stroke ICE mode,and part of the time as a hot cylinder of an alpha Stirling engine, each of the two working cylinders belonging to the fast crankshaft is connected by lines to a cold cylinder located on the fast crankshaft in series through a shut-off valve from the regenerator, a regenerator and a cooler, and form a group of cylinders using one working fluid, another cold cylinder, configured to remove heat, and two other convertible cylinders, configured to alternately operate in two strokes in mutually opposite modes: the mode of expansion of exhaust gases coming from the working cylinders of the fast crankshaft, and the alpha Stirling engine mode, wherein each cylinder of the slow crankshaft includes an intake valve, an exhaust valve and a shut-off valve from the regenerator and is connected to the cold cylinder in series through a shut-off valve from the regenerator, a regenerator and a cooler,at the same time, two convertible cylinders with a cold cylinder of a slow crankshaft form a group of cylinders using one working fluid, while the connecting rods of these working cylinders are ahead in phase of the connecting rod of the cold cylinder by an angle close to 90°, and the pistons of the convertible cylinders of the slow crankshaft are at TDC, when the pistons of the convertible cylinders of the fast crankshaft are at BDC, before the exhaust stroke in the ICE mode.

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