Fuel combustion-powered engine

Abstract

A heat engine operating on a combined thermodynamic cycle and efficiently converting fuel combustion energy into mechanical work as a result of both an original kinematic configuration of a piston-type gas generator, which provides for a high level of isochoric pressure increase, and the use of exhaust gas energy. The special design features of the gas generator obviate the need for the use of oil in the chambers, resulting in a simplification of the lubrication system, an absence of crankcase gases and oil burning, and an increase in service life. The engine is dynamically balanced without additional measures, is characterized by a low level of vibrations and noise and has a longer operating life by comparison with the prior art and significantly lower batch and mass production costs.

Description

[0001] An engine powered by combustion of fuel

[0002] The claimed technical solution relates to mechanical engineering products, in particular to engines that operate by burning fuel or thermal engines.

[0003] Heat engines are being improved to maximize the utilization of the energy generated by fuel combustion. To this end, combined engines have been developed that maximize fuel combustion efficiency by pre-compressing portions of air by pistons in combustion chambers (CCs), i.e., in enclosed spaces, while using the hot exhaust gases in a turbine to generate additional mechanical work. One of the most efficient such engines is the Napier Nomad (A. Judge, "Low-Power Gas Turbine Engines," Moscow, Foreign Literature Publishing House, 1963, pp. 239-240). This twelve-cylinder, two-stroke diesel engine utilizes ports in the cylinders and pistons that perform reciprocating motion. Exhaust gases enter the turbine, which drives a compressor located on the same shaft as the turbine.In addition, the turbine transmits rotation to the common power take-off shaft via a mechanical transmission. The compressor supplies compressed air to the engine cylinders to purge them and fill them with a fresh charge. After the air is compressed by the pistons, fuel is burned (heat is supplied to the working fluid) under conditions close to constant-volume heat supply (V = const). According to piston internal combustion engine (PICE) theory, the more precisely the V = const condition is met, the higher the thermal efficiency of the process. The Napier Nomad engine has high fuel efficiency, but is extremely complex, large in size and weight, and expensive to manufacture and maintain.

[0004] Gas turbine engines (GTEs) are significantly more compact, lighter, and structurally simpler. We will briefly describe the basic design and steady-state operation of one of the simplest GTE variants, a free turbine. A compressor (centrifugal, linear, or combined) compresses incoming ambient air to design parameters; the compressed air, through air ducts, enters the combustion chamber (CBC) with a flow path, where combustion of the fuel injected into the CBC is maintained under constant working fluid pressure (P = const). The resulting hot gases are directed through nozzles to the blades of a turbine, which is mounted on the same shaft as the compressor. The expansion of the gas in the turbine causes it to rotate and the compressor to compress the air before it enters the CBC. This part of the GTE is the gas generator (GG). The gases are then directed to the blades of the free turbine (FT), which imparts rotation to it. The ST has no mechanical connection with the GG and is fixed to the power take-off shaft (PTO) of the turbine.The main disadvantages of a gas turbine engine include: worse fuel efficiency than a combustion engine (especially in partial operating modes), a high requirement for air to maintain operation, and high cost.

[0005] There are free-piston engines with a turbine, consisting of the so-called free-piston gas generators (FPG) and a free gas turbine (A. Judge. Low-power nitrogen-turbine engines. - M.: Foreign Literature Publishing House, 1963, p. 241; P. A. Shelest. Combined turbo-piston engines. - M.: Mashgiz, 1958, p. 29). Engines of this type eliminate some of the shortcomings of gas turbine engines and engines with gas generators based on diesel. The FPG is a cylinder in which the pistons perform counter (and return) movements. An FPG engine operates on a two-stroke cycle as follows. At the point of closest approach of the pistons, air is compressed (in the case of a diesel thermodynamic cycle), into which fuel is injected. During self-ignition of the fuel, the temperature and pressure of the working fluid increase, and the pistons diverge after stopping.Each of the two working pistons is connected to the compressor piston via a rod and is housed in a compressor cylinder (each in its own cylinder). During the power stroke, air in the compressor cylinders is compressed and enters the receiver through the discharge valve in front of the cylinder's blowdown ports. As the working pistons move, they open the discharge ports, and hot gases flow through a pipeline to the gas turbine inlet where, expanding within it, they generate useful work on the turbine's PTO shaft. As the pistons continue to move, the blowdown ports open, purging and filling the cylinder with compressed air from the receiver. The reverse movement of the pistons occurs due to the expansion of compressed air in the harmful spaces of the compressor cylinders. After the turbine, the exhaust gases are discharged into the atmosphere. Symmetry of the piston movement relative to the cylinder's center point is ensured by a synchronization mechanism, which can have various design variations. LNGGs are distinguished by their design simplicity, becauseThey do not contain a crankshaft, connecting rods, or camshaft, and the pistons and ports cut into the cylinder walls act as valves for gas exchange. LNG engines are well dynamically balanced. A significant advantage of this engine is its high fuel efficiency compared to traditional diesel engines, and the torque curve on the free gas turbine shaft is favorable for use in locomotives, tractors, and other types of transport. The cost of LNG engines is significantly lower than that of a diesel engine of similar power. However, LNG engines have a number of disadvantages: difficulties in ensuring thermal stability and organizing gas exchange and mixture formation processes, regulating and automating LNG engine control; the complexity of resolving the issue of the reliability of the mechanisms synchronizing piston movement; difficulties in uniformly distributing oil over the working surfaces, reducing noise during operation, and driving and synchronizing the fuel supply equipment.In addition, a supply of compressed gas and a device for supplying it are required for starting.

[0006] An internal combustion engine (ICE) is known from patent RU 2613753, according to which the engine contains heat chambers and compressor chambers. Each "heat chamber-compressor chamber" pair is located within a common angular sector of a hollow ring with end partitions. The pistons of the compressor chambers and heat chambers are shaped like blades, which are paired together to form a single component (a bi-piston) that interacts with the walls of the angular sector and is rigidly attached to an intermediate shaft coaxial with the angular sectors of the chambers. The air intake duct interacts with the compressor chambers via their inlet valves. The engine also contains a receiver, which interacts with the compressor chambers via their outlet valves, and the receiver also interacts with the engine's heat chambers via their inlet valves. The engine also contains an output shaft and a spherical mechanism for converting the rotary-reciprocating (rocking) motion of the bi-pistons into unidirectional rotation of the output shaft.The spherical mechanism comprises a crank rigidly attached to the output shaft and a carrier pivotally connected to the intermediate shaft and crank. The carrier pivot axis passes through the intersection of the axes of both shafts and forms an acute angle with the output shaft axis equal to half the angular range of the bi-pistons' travel. The carrier pivot axis is orthogonal to the intermediate shaft axis and to the carrier pivot axis, also passing through the intersection of the axes of both shafts. The engine also comprises a flywheel, rigidly connected to the output shaft.

[0007] Combined heat engines are known in which four-stroke or two-stroke internal combustion engines (ICEs) are used as gas generators. The useful work they produce is expended exclusively on compressing air in the compressor, which is used to burn fuel in the ICE cylinders. This produces the maximum amount of exhaust gases, which rotate a free turbine, from whose shaft the useful work produced by the engine is extracted. (P.A. Shelest. Combined Turbo-Piston Engines. - Moscow: Mashgiz, 1958, pp. 15-26). The type of compressor is selected based on the specific task; it can be, for example, piston, centrifugal, axial, etc.

[0008] A combined engine of the specified type, which is being developed by one of the well-known European organizations, planning its use in aviation as a power plant for a promising turbofan aircraft engine, has been selected as a prototype for the claimed invention.

[0009] (https: / / icas.org / ICAS ARCHIVE / ICAS2018 / data / papers / ICAS2018 0638 pap er.pdf). According to the developers, their engine has improved characteristics compared to modern turbofan twin-circuit gas turbine engines, which are installed on modern airliners, including passenger and intercontinental transport aircraft. The main difference from traditional gas turbine engines is the use of a four-stroke piston diesel internal combustion engine as a gas generator. The engine contains working chambers in the form of cylinders with end partitions, which contain injectors for injecting fuel into the cylinders, intake and exhaust valves, actuated by a camshaft. The cylinders interact with their inner walls through movable seals with the pistons located within the cylinders.A crank mechanism is used to convert the reciprocating motion of the pistons into rotation of the output shaft. A high-pressure compressor, supplying the cylinders with a fresh charge, is kinematically linked to the output shaft. Air is filled into the cylinders and exhaust gases are discharged (during takeoff mode, through the constant-pressure combustion chambers traditional for gas turbine engines) to the gas turbine via appropriate air ducts. The exhaust ducts terminate in nozzles.

[0010] According to the developers, the use of a piston internal combustion engine to generate gases for rotating a free gas turbine, whose PTO shaft produces useful work and drives the low-pressure compressor, results in superior performance for this combined engine compared to traditional gas turbine engines. Specifically, a significant reduction in fuel consumption is claimed (up to 50% compared to aircraft engines of the early 21st century). This is achieved through higher working fluid pressure in the closed combustion chambers (CC) of the PCE (compared to the pressure in the CC of a gas turbine), and fuel combustion (i.e., heat supply to the working fluid) at a constant volume (V = constant). The gas generated under these conditions is fed to the free turbine without consuming energy to drive the high-pressure turbine, unlike traditional gas turbine engines.In addition to the above advantages, the developers point to a reduction in engine weight (compared to a turbofan gas turbine engine of similar thrust), noise and harmful emissions, and lower engine production costs.

[0011] The disadvantages of this engine include: increased length (compared to a gas turbine engine); a large number and high total mass of the components that make up the gas generator; the need for design solutions to eliminate vibrations caused by the second-order moments of inertia in the internal combustion engine with a crank mechanism (CRM); labor-intensive maintenance and repair; a large volume of oil required for the mechanism to function and its significant burnout.

[0012] The objective of the claimed invention is to increase efficiency; improve weight and size characteristics; simplify and reduce the cost of the design; increase service life; improve reliability; simplify maintenance and repair; reduce the cost of operation; reduce vibration, engine noise, and exhaust toxicity; simplify the lubrication system, reduce operating costs, and increase the service life of the oil.

[0013] The proposed engine (see Fig. 1, Fig. 2, Fig. 3, Fig. 4) comprises a high-pressure compressor 1, a high-pressure compressor shaft 2 connected to an output shaft 3 of at least one piston gas generator 4, the design of which includes chambers 5, which are angular sectors of hollow rings with end partitions 6. The walls of the chambers contain inlet ports 7 and outlet ports 8. The pistons of the piston gas generator are made in the form of blades, combined in pairs in one part - a bi-piston 9, which is a double-acting piston. The bi-pistons 9 are placed in the chambers 5. Each bi-piston 9 is rigidly fixed on an intermediate shaft 10, which is installed coaxially with the axis of the angular sectors of the chambers 5. The bi-pistons 9 interact with the walls of the chambers 5 with their contours.The transformation of the rotary-reciprocating motion of the bi-pistons 9 into the rotation of the output shaft 3 of the piston gas generator 4 is carried out using a corresponding mechanism: the axis of the intermediate shaft 10 intersects at a right angle with the axis of the output shaft 3 of the piston gas generator 4, which (shaft 3) contains a crank 11 rigidly fixed to it; on the intermediate shaft 10 and the crank 11, a link 12 is pivotally mounted, SUBSTITUTE SHEET (RULE 26) wherein the axis of the hinge joint 20 of the link 12 with the crank 11 passes through the point of intersection of the axes of the intermediate shaft 10 and the output shaft 3 of the piston gas generator 4 and forms with the axis of this shaft an acute angle equal to half the angular range of movement of the bi-pistons 9, and the axis of the hinge joint 20 of the link 12 with the intermediate shaft 10 is orthogonal to the axis of the latter and to the axis of the hinge joint of the link 12 with the crank 11 and also passes through the point of intersection of the axes of both shafts.The engine also contains a turbine 13 with a turbine power take-off shaft 14, through which a low-pressure compressor 15 is connected to the turbine 13, and through a fan reducer 16 - to a fan 17. In addition, the engine contains air ducts (not shown in the figures): inlet - for delivering a fresh charge to chambers 5; outlet - for removing exhaust gases into constant-pressure combustion chambers (similar to combustion chamber devices in traditional gas turbine engines, not shown in the figures), and then - into nozzles 19.

[0014] The proposed engine (in the variant with spontaneous combustion) operates in steady-state mode as follows. The piston gas generator is a two-stroke internal combustion engine in which bi-pistons, housed in chambers and rigidly mounted on an intermediate shaft, perform rotary and reciprocating movements relative to the axis of the intermediate shaft. As the bi-piston surface (bottom), which is the movable wall of the chamber (conventionally, the odd one), approaches top dead center (TDC), the same bi-piston surface in the even chamber approaches bottom dead center (BDC). At the same time, fresh air is compressed in the odd chamber, and at the calculated moment, fuel is injected through the fuel injector, which ignites, leading to an increase in pressure in the above-piston volume.In the even-numbered chamber, the bi-piston surface, which acts as the movable wall of this chamber, while moving toward its BDC, sequentially opens first the exhaust port (through which the exhaust gases of the even-numbered chamber, characterized by high pressure and temperature, exit through the exhaust air duct), then the inlet port (through which air compressed by the compressor enters the chamber via the intake air duct, purging the chamber and filling it with a fresh charge). In the odd-numbered chamber, after the bi-piston crown reaches TDC, the "power stroke" occurs during the bi-piston's return stroke, while in the even-numbered chamber, the "compression stroke" occurs. These processes are cyclically repeated in each of the chambers that make up the gas generator. The movement of the bi-pistons leads to a rotary and reciprocating motion of the intermediate shaft, to which the bi-pistons are rigidly attached.This movement of the intermediate shaft is converted into unidirectional rotation of the output shaft by a spherical mechanism comprising a crank rigidly attached to the piston gas generator's output shaft and a carrier pivotally engaged with the intermediate shaft and crank. The piston gas generator's output shaft is connected to a high-pressure compressor, which compresses the air needed to produce hot gases by the gas generator and to cool it. Exhaust gases formed during fuel combustion in the combustion chambers reach constant-pressure combustion chambers via exhaust ducts, whose design is similar to that of combustion chambers in traditional gas turbine engines. Due to the high oxygen content of these gases, constant-pressure combustion chambers provide additional heat to the working fluid (combustion of the fuel supplied to the constant-pressure combustion chambers) via the Brayton cycle (at P = constant).The gases then enter the turbine inlet, where the force acting on the turbine blades causes it to rotate. Useful work is extracted from the turbine's power take-off shaft, for example, to rotate a fan, which generates thrust in a bypass aircraft engine. At low and nominal loads, the engine operates in an economical mode: no fuel is supplied to the constant-pressure combustion chambers, and the turbine is powered by gases produced by the piston gas generator.

[0015] The proposed engine can be manufactured in several design variants, in particular:

[0016] - with ignition of the fuel-air mixture both from compression and from an external source;

[0017] - with a high-pressure compressor, made in the form of a piston compressor (Fig. 5), which contains one or more compressor chambers 21, made in the form of a sector of a hollow ring with end partitions with inlet and outlet valves (not shown in the diagram). In the compressor chambers 21, pistons 22 made in the form of blades are placed, interacting with their contours with the internal walls of the chambers by means of movable seals, and rigidly mounted on the intermediate shaft 10;

[0018] ' with movable seals 23, located on the inner walls of the chambers and interacting with the corresponding surfaces of the bi-pistons (Fig. 6);

[0019] - with the power take-off shaft 14 of the gas turbine 13, connected to the output shaft 3 of the piston gas generator 4 (Fig. 7);

[0020] - with an additional device for injecting a non-flammable liquid into the chambers, which (for example, being injected at the stage of expansion of the working fluid in the chamber during the “power stroke”) during the phase transition will provide high pressure of superheated steam acting on the bottom of the bi-piston, contributing to an increase in torque on the output shaft 3 of the piston gas generator 4, cooling the walls of the chamber 5 and the bottoms of the bi-pistons 9, and will also increase the production of gases for the operation of the turbine 13;

[0021] SUBSTITUTE SHEET (RULE 26) - with servo drives that change the position, size and shape of the inlet 7 and outlet 8 windows, to optimize the operation of the piston gas generator 4 under various load conditions;

[0022] - with special attachments - ejectors 23 on nozzles 19 (Fig. 8), which make it possible to add additional air from the environment to the gas stream from the nozzles, which can be directed both to the turbine blades and into the environment in order to increase the engine thrust in direct reaction mode.

[0023] SUBSTITUTE SHEET (RULE 26)

Claims

Invention formula 1. An engine comprising a high-pressure compressor, a high-pressure compressor shaft connected to the output shaft of a piston gas generator comprising chambers with end partitions interacting by means of movable seals with the inner surfaces of their walls with pistons located in the chambers, connected to a mechanism for converting the movement of the pistons in the chambers into rotation of the output shaft of the piston gas generator; inlet and outlet valves of the chambers; a turbine connected via a turbine power take-off shaft to a low-pressure compressor and to a fan via a fan gearbox; a constant-pressure combustion chamber; air ducts, in particular exhaust ducts, ending in nozzles; fuel and lubrication systems, characterized in that the chambers are arranged in pairs in the angular sectors of hollow rings with end partitions;The inlet and outlet valves are designed as inlet and outlet ports in the chamber walls in combination with pistons designed in the form of blades, combined in pairs in one part - a bi-piston, each of which is rigidly mounted on an intermediate shaft; the movable seals of the bi-pistons are designed as slot or labyrinth seals; the mechanism for converting the rotary-return motion of the intermediate shaft into rotation of the output shaft of the piston gas generator is designed as a spherical mechanism including an intermediate shaft, a crank rigidly fixed to the output shaft of the piston gas generator and a carrier pivotally connected to the intermediate shaft and the crank.

2. The engine according to paragraph 1, characterized in that the high-pressure compressor is designed as a piston compressor with one or more compressor chambers, each of which is designed in the form of a sector a hollow ring with end partitions with inlet and outlet valves and pistons placed in the compressor chambers, made in the form of blades rigidly mounted on an intermediate shaft, interacting with their contours with the internal walls of the compressor chambers by means of movable seals.

3. An engine according to claim 1, characterized in that the movable seals are made in the form of sealing elements located on the inner walls of the chambers, interacting with the surfaces of the bi-pistons in contact with them.

4. The engine according to paragraph 1, characterized in that the turbine power take-off shaft is kinematically connected to the output shaft of the gas generator.

5. An engine according to claim 1, characterized in that it contains a device for injecting non-flammable liquid into the chambers.

6. An engine according to claim 1, characterized in that the inlet and outlet windows in the walls of the chambers are adjustable.

7. The engine according to claim 1, characterized in that the nozzles are equipped with ejectors.

8. An engine according to claim 1, characterized in that at least one nozzle, with or without ejectors, is directed directly into the environment.

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