RU2827275C1 - Method of operating aircraft power plant - Google Patents

Abstract

FIELD: aircraft engine building.

SUBSTANCE: invention can be used, for example, for an unmanned aerial vehicle. Connecting rod 3 of the additional engine through crank 1 drives shaft 2 with propeller 11 (creating the thrust force from the discharged air) and through freewheel clutch 12—compressor 13, forcing air 14 into combustion chamber 17, into which fuel is simultaneously injected through nozzles 16 and ignited with plug 15 obtained combustible mixture. Combustion products are fed through turbine 18 into nozzle 19 and flow therefrom, creating a reactive thrust force. Turbine (compressor) rpm will increase and after propeller rpm is exceeded, clutch disengages. As a result, the propeller will continue to rotate from the additional engine at a relatively low frequency, and the turbine—at a high frequency. At the same time independent control of both engines is possible.

EFFECT: simpler design, higher reliability and improved performance.

9 cl, 10 dwg

Description

The invention relates to aircraft engine building and can be used, for example, for an unmanned aerial vehicle.

The prototype is a turboprop engine containing a propeller, an air intake, a compressor, a combustion chamber, a turbine, a jet nozzle, and the engine is made according to a two-shaft design, with a Stirling engine installed behind the turbine, connected by an internal shaft through a gearbox or multiplier to the propeller [Patent RF 2334892, IPC F02K 3/04, 2008].

The disadvantages of the prototype are:

- a relatively complex engine design, due to the presence of a starter for starting it, as well as the use of a gearbox or multiplier for rotating the propeller, which requires a lubrication system during operation;

- relatively low reliability, since, despite the presence of two engines in the power plant, they both stop working in the event of failure of the turbojet engine;

- long time to bring the power plant into operating mode.

The objective of the invention is to simplify the design, increase its reliability and improve operational characteristics.

The problem is solved by the fact that in the method of operation of the power plant of an aircraft, including the creation of reactive and propeller-thrown thrust forces by means of engines with rotating shafts, respectively, the main and additional, the latter being kinematically connected to the propeller, autonomous, independent operation of the engines is ensured, while their shafts are connected in a kinematic chain with a changing number of degrees of freedom.

The number of degrees of freedom of the kinematic chain is changed by means of an overrunning clutch, the half-clutch of which is rigidly connected to the engine shafts. The clutch is made integral with the safety element. The main engine is started by means of an additional engine. The additional engine is also used as a compressor. The compressor is used to supply fuel, at least to the main engine. The additional engine is started by rotating the propeller. The additional engine is started by rotating the propeller in a horizontal plane. An internal combustion engine is used as an additional engine.

The specified distinctive features allow achieving the following advantages in comparison with the prototype.

Providing autonomous, independent operation of engines, and connecting their shafts into a kinematic chain with a variable number of degrees of freedom allows increasing the reliability of the engine, since in the event of one engine failure, the power plant continues to operate. In addition, the variable number of degrees of freedom of the kinematic chain makes it possible to abandon the gearbox and change the rotation frequency of the main engine shaft independently of the rotation frequency of the additional engine shaft, which improves operational characteristics.

Changing the number of degrees of freedom of the kinematic chain by means of an overrunning clutch, the half-clutch of which is rigidly connected to the engine shafts, helps to simplify the design, since during its operation the overrunning clutch does not require a lubrication system.

The implementation of the coupling together with the safety element increases the reliability of the power plant, since in the event of a jamming of the main engine shaft, the additional one continues to operate in its normal mode.

Starting the main engine using an additional engine eliminates the need for a starter, which simplifies the design, increases its reliability and improves performance characteristics.

The use of an additional engine as a compressor helps to maintain the power of the main engine, since in this case there is no need to divert compressed air for the power plant’s own needs, for example, for the operation of the gas shaft supports.

Using a compressor to supply fuel, at least to the main engine, also helps to conserve power from the main engine, some of which will not be taken to supply fuel, which improves performance.

The implementation of starting an additional engine by rotating the propeller simplifies the design of the power plant, increases its reliability and improves operational characteristics.

The launch of an additional engine by rotating the propeller in a horizontal plane allows the aircraft to take off vertically with such a power plant, which improves operational characteristics.

The use of an internal combustion engine as an additional engine makes its operation independent from the main engine, which increases the reliability of the power plant.

The invention is illustrated by drawings.

Fig. 1 shows the internal combustion engine at the moment when the piston is at the 0.7 mark of the stroke. Fig. 2 shows the engine at the moment when the piston is at the 0.96 mark. Fig. 3 shows the engine at the moment when the piston is at the 0.96 mark during the return stroke of the piston from the extreme position. Fig. 4 shows the engine at the moment when the piston is near the middle. Fig. 5 shows the engine at the moment when the piston is at the 0.03 mark. Fig. 6 shows the engine at the moment when the piston is at the 0.03 mark during the return stroke of the piston from the extreme position. Fig. 7 shows the engine cylinder with a piston having two rods. Fig. 8 shows the engine in the compressor mode. Fig. 9 shows the power plant of the aircraft. Fig. 10 shows a section of the overrunning clutch with a safety element.

The power plant of the aircraft comprises an additional engine - a crank-slider mechanism, the crank 1 of which is rigidly fixed on the shaft 2 and connected via the connecting rod 3 to the rod 4 of the piston 5, located with the possibility of movement in the cylinder 6, in the center of the cavity of which a window 7 is made, connecting this cavity with the atmosphere, and on the cylinder covers a fuel injection device 8 is located. The cylinder can have valves 9, 10, connected by air ducts with similar valves located at the opposite ends (covers) of another cylinder. The propeller 11 is fixed on the shaft, which is kinematically connected via the clutch 12 to the compressor 13 of the main engine, forcing air 14 into the combustion chamber 17 having a spark plug 15 and fuel injectors 16, the combustion products of which enter the atmosphere via the turbine 18, kinematically connected to the compressor shaft, and the nozzle 19. The coupling can be made in the form of a ring (one half coupling) 20, in which a groove is made with a cantilever beam 21, contacting the rolling body 22, pressed by a spring 23 to its wedging surface 24 and to the shaft 25 (the other half coupling).

The method is implemented as follows.

Let us assume that the additional engine is started in a known manner, for example by turning the propeller (by hand or by tugging the end of a rope wound on the shaft) and rotating shaft 2, for example clockwise, with the angle of rotation being counted from the horizontal. For the sake of certainty, we will assume that at the initial moment (at the moment of starting) shaft 2 occupies a position corresponding, for example, to its angle of rotation α=30° (Fig. 1). At this time, piston 5 is at a distance of 0.7 of the stroke. In this case, in the right part of the cavity of cylinder 6, air will be compressed by piston 5, and the air pressure will increase as the piston approaches the dead point. When shaft 2 reaches angle α=70°, piston 5 will be at a distance of 0.96 of the stroke, and window 7 will begin to be released from the adjacent cylindrical surface of the piston (open), as a result of which air (or combustion products) from the left part of the cavity of cylinder 6 will flow out (into the atmosphere), and the pressure in this part of the cavity will drop, after which it will be blown out and filled with fresh air (Fig. 2). This figure shows one window 7 conditionally, but there may be more windows, and all of them should be located around the circumference of the cylinder.

Then fuel is injected through device 8 (injector), which, when in contact with hot compressed air, ignites and begins to burn. (If this engine operates with technical ignition, then after fuel injection the mixture is ignited, for example, using a spark plug). Piston 5 continues to move by inertia toward the dead point, further freeing window 7. The resulting combustion products press on the said piston, forcing it to move after passing the dead point in the opposite direction. When shaft 2 passes an angle of 110°, piston 5 will again be at the 0.96 mark of the stroke, moving in the opposite direction, and window 7 will begin to finally close, and purging and filling the cylinder with fresh air will end (Fig. 3). When the piston moves along the windows, it is cooled by the flow of outside air, due to which it does not overheat during engine operation.

Next, fresh air in the left part of the cylinder cavity 6 will begin to be compressed by piston 5 (Fig. 4). As soon as the piston is near the ~ 0.03 mark, window 7 will begin to open slightly, releasing combustion products from the right part of the cylinder cavity, the pressure in it will drop, and it will be blown through and filled with fresh outside air (Fig. 5). At the same time, left injector 8 injects fuel, which ignites and begins to burn. After the shaft has passed an angle of 290°, piston 5 will be at the 0.03 mark of the stroke. Window 7 will begin to finally close, the piston will begin to compress the air in the right part of the cylinder cavity 6 (Fig. 6). When shaft 2 turns 390°, the described cycle will be repeated. In this case, the engine does not have a valve timing mechanism, which significantly simplifies its design and reduces its weight.

If piston 5 is connected on the other side by a second rod 4 and the latter is kinematically connected via crank 1 to the second power take-off shaft (Fig. 7), then another consumer can be connected to the engine, which can also be propeller 11 (air screw), which can simultaneously become the engine flywheel. Since this system has one degree of freedom, the propellers can be fixed mutually perpendicularly and brought closer together so that their rotation trajectories intersect, but they will not collide. In this case, when starting the engine, it is necessary to rotate shafts 2 (propellers 11) in different directions, and the propellers must be installed so that the air flows they create are unidirectional. Such a convergence of the propellers increases the air flow at the wide part of the wings (closer to the fuselage) and maintains a sufficiently large flow at the edge of the wings, which increases the lifting force of the aircraft. If the propeller operates in a horizontal plane, the aircraft can perform a vertical lift, standing, for example, on its tail. Similarly, it is possible to perform a vertical descent of the aircraft, making the thrust force created by the propeller slightly less than the force of gravity acting on the said aircraft.

If the engine cylinders are equipped with valves 9, 10, then it is possible to periodically alternately use the cylinder-piston group of each cylinder as an air blower (compressor), for example, to supply fuel (Fig. 8). Let us assume that the piston of the upper cylinder moves to the left and compresses air, and the piston of the lower cylinder goes to the right and is at the 0.03 stroke mark and begins to close the window of the 7th cylinder. After this window is completely closed, valves 9, 10 are opened, respectively, at the upper and lower cylinders. Since the air pressure in the cavity of the upper cylinder is greater than in the cavity of the lower one, the air from the upper cylinder rushes into the lower one, the pistons continue to move. When the upper piston reaches the left dead center, these valves are closed, the lower piston at this moment will be near the middle and will continue to move, further compressing air. In the upper cylinder, the piston will start moving backwards, the blowdown and filling of the right part of the cavity with air will be completed, and the piston will begin to compress the air in it. Note that the compressed air remaining in the left cover of the upper cylinder (air cushion) will facilitate the movement of the upper piston in the opposite direction. Moreover, it is possible to inject a small amount of fuel with the left upper nozzle to increase the pressure by means of combustion products and, thus, organize a low-power working stroke, which will further facilitate the return stroke of the upper piston. When the lower piston approaches the right dead center, fuel is injected by nozzle 8, as a result of which the combustible mixture burns, forming the working stroke of the piston of the lower cylinder, and the blowdown and filling of its left part with air will be completed. After the lower piston closes the window 7, valves 9 and 10 of the lower and upper cylinders, respectively, open, as a result of which the air from the right part of the upper cylinder will rush into the left part of the cavity of the right cylinder. When the upper piston reaches the right dead center, the said valves are closed, the piston of the lower cylinder will continue to compress the air in the left part, and when it reaches the ignition advance angle, fuel is injected by the left injector 8, thereby organizing the working stroke of the piston. Then the described process is repeated. The lower cylinder will operate in the engine mode, and the upper one - in the supercharger (compressor) mode. As a result, the cavity of the lower cylinder will receive twice as much air as usual. Due to this, the engine will also be able to operate in a more rarefied air space, in order to maintain the thermal mode of the cylinders, their operating mode can be periodically changed, i.e. first one works in the compressor mode, and the other in the engine mode, and then vice versa. Note that the compressor mode can be implemented with only one cylinder. To do this, do not inject fuel into one of the halves, but use the air compressed in this half as compression air, which will flow out of the specified half after opening an additional valve (not shown). In addition, under certain flight conditions, the compressor can operate from a propeller rotating due to autorotation from the oncoming air flow, which will reduce fuel consumption.

For better blowing and filling the cylinder cavity with fresh outside air, the lower part of the windows is placed in a zone of high pressure, for example under the wing of an aircraft, and their upper part is placed in a zone of low pressure, for example above this wing.

After the additional engine is switched on, it becomes possible to start the main engine. Since the compressor shaft 13 rotates through the clutch 12 (for example, the overrunning clutch), the air 14 entering the compressor will be compressed and enter the combustion chamber 17, into which fuel is simultaneously injected through the nozzles 16 and the resulting combustible mixture is ignited by the spark plug 15. The combustion products will enter the nozzle 19 through the turbine 18 and flow out of it, creating a reactive force. The turbine (compressor) revolutions will increase and, as soon as its rotation frequency exceeds the propeller rotation frequency, the number of degrees of freedom will change from one (when the half clutches rotated together) to two (when the half clutches rotate with different angular velocities). As a result, the propeller will continue to rotate from the additional engine at a relatively low frequency, and the compressor (turbine) - at a high frequency. In this case, independent control of both engines is possible. Note that if one of the engines fails, the other will continue to operate independently of it. However, if the compressor shaft jams for some reason and stops rotating, the additional engine will also stop. To eliminate the possibility of such a stop, the overrunning clutch is equipped with a safety element in the form of a cantilever beam 21 (Fig. 10). At different rotation speeds of the half couplings, the rolling element 22 moves away from the jamming surface 24, overcoming the force of the spring 23, allowing the ring 20 and the shaft 25 to rotate relative to each other. When the overrunning clutch is activated, the rolling element 22 moves to the jamming surface 24, and the ring 20 rotates together with the shaft 25. In the event of an increase in the torque transmitted by the clutch greater than the permissible value, the rolling element 22 will move along the jamming surface 24 of the cantilever beam 21 and, having passed the entire jamming surface, will begin to rotate, no longer preventing the rotation of the shaft 25 relative to the ring 20. Therefore, in the event of jamming of the compressor shaft, the additional engine will continue to operate.

The implementation of the invention will allow the creation of a simple, reliable and convenient power plant, allowing, for example, an unmanned aerial vehicle to take off and land in a vertical position if necessary, since the main engine, which creates the jet thrust force, can be switched off, and therefore it will not interfere with keeping the aircraft in a vertical position on the ground. The ability to start a flight on an additional engine reduces the time of pre-flight preparation.

Claims (9)

1. A method of operating an aircraft power plant, including the creation of reactive and propeller-thrown thrust forces by means of engines with rotating shafts, respectively, the main and additional, the latter being kinematically connected to the propeller, characterized in that autonomous, independent operation of the engines is ensured, while their shafts are connected in a kinematic chain with a variable number of degrees of freedom, and a propeller is used as a propeller, which increases the lifting force of the aircraft. 2. The method according to paragraph 1, characterized in that the number of degrees of freedom of the kinematic chain is changed by means of an overrunning clutch, the half-clutch of which is rigidly connected to the motor shafts. 3. The method according to any of paragraphs 1, 2, characterized in that the coupling is made integral with the safety element, which is made in the form of a cantilever beam with a rolling element pressed by a spring to its wedging surface. 4. The method according to paragraph 1, characterized in that the main engine is started using an additional engine. 5. The method according to paragraph 1, characterized in that the additional engine is also used as a compressor by periodically alternately using the cylinder-piston group of each cylinder as an air blower. 6. The method according to any of paragraphs 1, 5, characterized in that the compressor is used to supply fuel to at least the main engine. 7. The method according to paragraph 1, characterized in that the additional engine is started by rotating the propeller. 8. The method according to any of paragraphs 1, 7, characterized in that the additional engine is started by rotating the propeller in a horizontal plane. 9. The method according to paragraph 1, characterized in that an internal combustion engine is used as an additional engine.