Aircraft engine with variable area exhaust nozzle

Abstract

The present invention provides an engine 310 for a vertical take-off and landing aircraft 300. The engine is configured to be movable relative to an aircraft part 342 of the aircraft 300 between a hover position for take-off and landing and a cruise position for forward flight. The engine 310 comprises an aerodynamic part 332 having at least one aerodynamic element 334 movable between a first position 336 according to a first operating state of the aircraft and a second position 338 according to a second operating state of the aircraft, the aerodynamic element defining an aerodynamic surface in contact with the airflow through the engine.

Description

Detailed Description of the Invention

[0001] The present invention relates to an engine for a vertical take-off and landing aircraft. The engine is configured to be movable relative to an aircraft component of the aircraft between a hovering position during take-off and landing and a cruise position during forward flight. The present invention further relates to a vertical take-off and landing aircraft provided with such an engine.

[0002] Vertical take-off and landing aircraft (VTOL aircraft) have attracted increasing attention in recent years due to their ability to take off and land in areas with limited space such as urban areas. Extensive research and development efforts have been devoted to optimizing engines for VTOL aircraft to improve engine efficiency and performance in both hovering mode (during take-off and landing) and cruise mode (during forward flight). One of the challenges in the design of VTOL aircraft engines is that the engine aerodynamics, such as the shape of the flow region at the inner wall of the duct and the intake and exhaust sections, and the shape and angle of rotor blades and stator blades, can only be optimized for a single flow state. However, particularly in VTOL aircraft, both the operating requirements and the load of the engine differ greatly between the hovering mode during take-off and landing on the one hand and the cruise mode during forward flight on the other hand. As a result, engines for VTOL aircraft are typically designed to be oversized to enable reliable operation in both modes.

[0003] As an example of changing aerodynamic conditions in an engine by means of movable aerodynamic elements, variable area exhaust nozzles have historically been used in gas turbines for conventional jet aircraft, where the exhaust nozzle area of the engine is changed to optimize flow conditions to accommodate different flight conditions. This can result in reduced energy consumption while enabling thrust generation adapted to the specific requirements of a given flight situation. In particular, variable area exhaust nozzles can adjust the static pressure at the exhaust section of the engine to create optimized flow conditions for different operating conditions. Conventionally, variable area exhaust nozzles are adjusted by dedicated actuators.

[0004] U.S. Patent No. 4,176,792 discloses a convergent-divergent nozzle comprising a four-bar linkage system and multiple servo actuators for multiple jaws to change the exhaust nozzle area. Such variable-area exhaust nozzles have multiple complex coupling components and consume a considerable amount of fuel due to their heavy weight.

[0005] Another variable-area exhaust nozzle for engines is known from U.S. Patent No. 1,0570,926. This other variable-area exhaust nozzle features a jaw that is adjusted by a dedicated actuator to account for the flight mode. Here again, the actuator significantly increases the aircraft's weight and fuel consumption. Furthermore, the nozzle requires considerable installation space.

[0006] Therefore, an object of the present invention is to provide an engine having improved aerodynamic conditions in multiple different operating modes while limiting complexity and / or weight. This objective is achieved by the engine of a vertical take-off and landing aircraft. The engine is configured to move relative to the aircraft's aircraft components between a hovering position for take-off and landing and a cruising position for forward flight. The engine includes a variable-area exhaust nozzle attached to the engine's exhaust section. The variable-area exhaust nozzle includes an aerodynamic component having at least one aerodynamic element that is movable between an open position and a closed position relative to the engine. The engine includes a transmission, the first end of which is configured to be connected to the variable-area exhaust nozzle and the second end to be connected to the aircraft components. The transmission is configured to convert the engine's movement relative to the aircraft components into the movement of at least one aerodynamic element. Thus, according to a key feature of the present invention, by providing a variable-area exhaust nozzle having an aerodynamic element that is movable according to the flight mode, it becomes possible to change the aerodynamic conditions within the engine in both hovering and cruising modes and adapt the airflow to the optimal operation of the engine. Specifically, by moving the aerodynamic elements, the aerodynamic surface—for example, the angle of the aerodynamic surface relative to the incoming airflow or the angle at which the airflow collides with the aerodynamic surface—also changes the aerodynamic cross-section of the exhaust region or the exhaust portion of the engine, thus changing the engine's operating characteristics to match the flight mode. Therefore, aerodynamic components can be adjusted to ensure equivalent or similar flow coefficients and reduced friction losses, as well as operation at the engine's effective operating point, in both hovering and cruising modes.

[0007] According to the present invention, the engine is equipped with a transmission configured to convert the engine's motion relative to aircraft components into the motion of at least one aerodynamic element, namely the opening and closing motion of a variable-area exhaust nozzle. Therefore, in a vertical take-off and landing aircraft using such an engine, the engine's motion between the cruising position and the hovering position can be directly transmitted to the aerodynamic element of the variable-area exhaust nozzle, causing the aerodynamic element to move. As a result, the variable-area exhaust nozzle can be configured to suit a particular flight mode (hovering or cruising). Specifically, the transmission may be configured to set the variable-area exhaust nozzle (i.e., the aerodynamic element) to the open position when the engine is in the hovering position, and to set the variable-area exhaust nozzle (i.e., the aerodynamic element) to the closed position when the engine is in the cruising position. It has been found that the engine, and therefore the aircraft, achieves optimal performance when the ratio of the exhaust nozzle area during cruising (i.e., the exhaust cross-sectional area with the nozzle closed) to the exhaust nozzle area during hovering (i.e., the exhaust cross-sectional area with the nozzle open) is set within the range of 0.53 to 0.76, preferably within the range of 0.61 to 0.69, and most preferably within the range of 0.65.

[0008] The first advantage of the transmission is that it eliminates the need for a separate actuator to drive the variable-area exhaust nozzle, thereby reducing engine complexity and weight. Because the transmission is a completely mechanical device, it avoids the need for additional electrical or electromechanical components such as actuator control systems. The second advantage of the transmission is that since the movement of the variable-area exhaust nozzle is determined by the movement of the engine, one degree of freedom in control and testing is eliminated, resulting in reduced control effort and improved safety. Furthermore, testing effort is significantly reduced because it is no longer necessary to test every position or opening of the variable-area exhaust nozzle for every position of the engine on any axis of rotation during hovering and cruising.

[0009] The variable-area exhaust nozzle, to which the engine is movably mounted, may be an airfoil such as a wing or canard, or it may be the aircraft fuselage, or a component fixed to the airfoil or aircraft fuselage. Therefore, it is preferable that a structure fixed to the aircraft's main carrier is selected as the reference point for controlling the movement of the variable-area exhaust nozzle.

[0010] In a preferred embodiment of the present invention, the range of motion of the engine relative to the aircraft component between a hovering position and a cruising position includes a first range and a second range, and the transmission is configured to have a first transmission ratio when the engine is moving within the first range and a second transmission ratio lower than the first transmission ratio when the engine is moving within the second range. Thus, the transmission is provided with different transmission ratios depending on the engine's position relative to the aircraft component. For example, even when the engine turns from hovering mode to cruising mode at a constant angular velocity, the turning motion of the associated aerodynamic elements may be performed at two or more different speeds depending on the engine's position. Thus, the opening of the variable-area exhaust nozzle can be set as required for each position on the engine's turning axis.

[0011] Furthermore, the range of motion of the engine relative to the aircraft components between the hovering position and the cruising position may include the idle range, and the engine's movement within the idle range is not translated into the movement of the aerodynamic elements. In particular, the position of the aerodynamic elements relative to the engine may be fixed while the engine is moving within the idle range. In this way, the adjustment of the opening of the variable-area exhaust nozzle is adaptable to intermediate states between the hovering position and the cruising position.

[0012] To achieve idle range functionality by simple mechanical means, the aerodynamic element or transmission may remain in contact with a mechanical stop for fixing the position of the aerodynamic element relative to the engine within the idle range, and / or the transmission may include an elastic member positioned to adjust the engine's movement relative to the aircraft component within the idle range so that the engine's movement is not translated into a change in the opening of the variable-area exhaust nozzle.

[0013] The transmission preferably includes linking means such as a rod and / or cam mechanism, more specifically a slotted cam. In particular, when a cam mechanism is used, the movement of the aerodynamic element can be predetermined as dependent on the relative position between the engine and the aircraft component by selecting a specific shape of the cam surface of the cam mechanism (such as the shape of the slots in a slotted cam). Furthermore, the aerodynamic element may be biased toward a first or second position by an elastic member, such as a tension spring, and moved by simple mechanical means.

[0014] Another reliable mechanical transmission designed to bridge the relatively long distance between an aircraft component and a variable-area exhaust nozzle may comprise a pulley transmission. Specifically, the pulley transmission comprises at least one first pulley connected to an aerodynamic element, a second pulley configured to be connected to or fixed to the aircraft component, and a belt that transmits the movement of one pulley to the other. To provide different transmission ratios depending on the engine's position relative to the aircraft component, at least one of the pulleys may have a non-circular cross-section. A non-circular cross-section is any cross-section that deviates from a single circle. The belt may be tensioned by a tensioning means.

[0015] In another embodiment of the present invention, the variable area exhaust nozzle comprises a first aerodynamic element and a second aerodynamic element, the first and second aerodynamic elements connected to each other by a linkage mechanism, preferably a linkage mechanism with a link and / or slotted cam, such that the movement of the first aerodynamic element drives the movement of the second aerodynamic element. Thus, the transmission only needs to drive the first aerodynamic element, and the second aerodynamic element (or additional aerodynamic element) can be driven by the first aerodynamic element via the linkage mechanism. Therefore, an additional transmission or actuator for the second aerodynamic element (or further aerodynamic element) can be omitted.

[0016] In another embodiment of the present invention, the engine may be equipped with an aerodynamic control device. The aerodynamic control device is configured to control the movement of aerodynamic elements based on the engine's movement relative to the aircraft components. As a result, the movement of the aerodynamic elements is directly linked to the engine's movement between the hovering position and the cruising position through dedicated control via the control device. Dedicated control in this sense means that the control device operates at the electronic and / or hardware level and that it is ensured that the operation of the control device is not disabled by the aircraft's flight computer and / or pilot commands, at least under normal (non-emergency) operating conditions of the aircraft. In this way, one degree of freedom in control and testing is eliminated, resulting in reduced control effort and improved safety. Furthermore, testing effort is also significantly reduced because it is no longer necessary to test every position or opening of the variable-area exhaust nozzle for every position on the engine's pivot axis.

[0017] For example, the control device may be connected to receive signals from an engine mode actuator that moves the engine between a hovering position and a cruising position. In addition, or alternatively, the control device may be part of a transmission, such as the transmission described in the various embodiments above, or may be connected to a transmission.

[0018] In a preferred embodiment of the present invention, at least one aerodynamic element is a baffle plate or jaw of a variable-area exhaust nozzle configured to deflect the engine exhaust flow and define the engine's exhaust region. By adjusting the engine's exhaust region, the static pressure within the engine can be adapted to the current load and a particular flight mode, allowing the engine to operate at an equivalent or at least similar effective operating point during both hovering and cruising.

[0019] More specifically, the aerodynamic element may be a typical C-shaped jaw when viewed from the direction of the engine's thrust, so that the jaw can at least partially enclose the exhaust region. For example, two typical C-shaped jaws, when positioned so that their C shapes face each other, can define the exhaust region and allow the exhaust region to be changed between the open and closed positions of the nozzle. Furthermore, depending on the specific C shape of at least one jaw, the exhaust region may be configured as circular or substantially polygonal, for example, substantially rectangular. To reduce turbulence, the substantially polygonal shape may have rounded edges.

[0020] The present invention further provides a vertical take-off and landing (VTOL) aircraft comprising aircraft components such as a fuselage and wings, and one or more engines configured according to the embodiments of the present invention described above. The VTOL aircraft comprises an airfoil and a plurality of engines, preferably more than five, more preferably more than ten, which are mounted adjacent to each other on the airfoil in a row that allows the airflows of adjacent engines to merge and support each other. This enables distributed propulsion.

[0021] Each engine may be able to rotate relative to the airfoil independently of the other engines. In particular, each engine may rotate relative to the airfoil to take a different position (angle relative to the airfoil) from the other engines, especially its adjacent engine or all other engines. This can enhance maneuverability and operational redundancy.

[0022] Alternatively, an engine system with multiple fixed engines, for example three engines, may be used, and the multiple engines may be rotated simultaneously by rotating the engine system. Furthermore, such an engine system may have one common variable-area exhaust nozzle such that the exhaust areas of all the multiple engines are controlled by a common variable-area exhaust nozzle. The multiple engines of the engine system may be arranged in a line, particularly in a line extending laterally, such that the engines are arranged adjacent to one another.

[0023] In all embodiments of the present invention, in order to control the aerodynamic load acting on the blade, at least one engine or at least one engine device may be attached to the trailing edge of the airfoil. Furthermore, in order to control the airflow on the upper side of the airfoil, at least one engine or at least one engine device may be attached to the upper portion of the airfoil.

[0024] The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] [Figure 1] 1 shows a schematic arrangement diagram of an aircraft including an engine device and a variable area exhaust nozzle according to a first embodiment of the present invention. [Figure 2a-2b] 2a and 2b are cross-sectional views of engine devices each provided with a variable area exhaust nozzle according to a first embodiment and a second embodiment of the present invention, respectively. [Figure 3a-3b] 3a and 3b show a variable area exhaust nozzle in a closed position (Fig. 3a) and an open position (Fig. 3b) according to a third embodiment of the present invention. [Figure 4a] 4 shows a variable area exhaust nozzle in a closed position according to a fourth embodiment of the present invention. [Figure 4b-4c] 5 shows a modified example of the variable area exhaust nozzle in a closed position according to the fourth embodiment of the present invention. [Figure 5] 6 shows a variable area exhaust nozzle in a closed position according to a fifth embodiment of the present invention. [Figures 6a-6b] 7a and 7b show a variable area exhaust nozzle in a closed position (Fig. 6a) and an open position (Fig. 6b) according to a sixth embodiment of the present invention. DESCRIPTION OF EMBODIMENTS

[0026] Throughout this disclosure, directions generally refer to the conditions when the aircraft is parked or flying parallel to the ground. This means that the aircraft's direction of travel X extends along the aircraft's roll axis, the lateral direction Y extends horizontally along the aircraft's lateral axis (pitch axis), and the vertical direction Z extends upward along the aircraft's vertical axis (yaw axis).

[0027] In Figure 1, a vertical take-off and landing (VTOL) aircraft is generally denoted by reference numeral 100. The aircraft 100 comprises a fuselage 101 and an airfoil section 102, for example, a pair of wings 102a located at the rear of the fuselage 101 and a pair of canards 102b located at the front of the fuselage 101. Each airfoil section 102 is equipped with at least one, preferably more, engine units 106, each engine unit 106 comprising at least one engine 110, specifically an electric engine such as an electric ducted fan. In the illustrated example, each engine unit 106 includes three engines 110.

[0028] Since the multiple engines 110, preferably more than five, are arranged in a line adjacent to each other, the airflows from adjacent engines merge and support each other, thereby forming a continuous flow with a relatively large lateral width. In the illustrated example, the rear wings 102a each have more than 10 engines, specifically 12, and the canard wings 102b each have more than 5 engines, specifically 6. As a result, the total number of engines is more than 30, specifically exactly 36, which allows the aircraft to operate with high redundancy, high efficiency, and low noise.

[0029] Each engine unit 106 is rotatably mounted on the airfoil 102 so as to be able to rotate around a lateral engine rotation axis between a hovering position suitable for takeoff and landing and a cruising position suitable for forward flight. In the hovering position, the thrust direction of at least one engine 110 of the engine unit 106 is directed in the vertical direction Z. In the cruising position, the thrust direction of at least one engine 110 of the engine unit 106 is directed substantially parallel to the direction of travel X.

[0030] According to a first embodiment of the present invention, each engine device 106 is equipped with a variable area exhaust nozzle 130 attached to the exhaust portion of the engine device 106. The variable area exhaust nozzle 130 preferably includes a jaw device 132 having at least one movable jaw 134, preferably two jaws, configured to move between an open position defining a relatively large exhaust nozzle area and a closed position defining a relatively small exhaust nozzle area.

[0031] When one engine unit has only one variable-area exhaust nozzle 130, and one engine unit 106 includes multiple engines, for example, three engines 110, it is preferable that the exhaust regions of all engines are controlled by a common variable-area exhaust nozzle.

[0032] The variable exhaust nozzle 130 can be moved to define different openings corresponding to different exhaust nozzle regions, specifically, the cruising exhaust nozzle region when set to a closed or cruising configuration, and the hovering exhaust nozzle region when set to an open or hovering configuration. By changing the exhaust nozzle region for cruising and hovering, the static pressure of the exhaust portion changes, and the aerodynamic characteristics can be adapted to the cruising and hovering positions. Thus, the engine 110 can operate efficiently as desired, particularly during both cruising and hovering flight, with similar effective operating points and / or similar flow conditions. It has been found that the engine, and therefore the aircraft, achieves optimal performance when the ratio of the exhaust nozzle regions for cruising to hovering is set within the range of 0.53 to 0.76, preferably within the range of 0.61 to 0.69, and most preferably 0.65.

[0033] Figure 2a shows details of the engine unit 106 of the first embodiment in the cruising position. The engine 110 includes an engine housing 112 extending in the direction of travel X from an inlet section 114 to an exhaust section 116. A rotor 122 having rotor blades 124 and stator blades 126 is arranged inside the engine housing 112. The stator blades 126 hold the rotor 122 at the center of the engine housing 112.

[0034] Adjacent to the exhaust section 116, a variable area exhaust nozzle 130 is mounted on the engine housing 112. The variable area exhaust nozzle 130 includes a jaw device 132. The jaw device 132 has at least one jaw 134 that is movable around a jaw pivot axis 134a, which may be positioned in the lateral direction Y. The jaw pivot axis 134a is indicated by a dashed cross. The jaw device 132 is movable between an open position 136 (not shown) and a closed position 138.

[0035] In the closed position 138, two adjacent jaws 134 can substantially contact each other in the vertical direction Z. Furthermore, the distance 133 between the circumferential surfaces 135 of adjacent jaws 134 decreases from one end of the exhaust portion 116 to the opposite end in the direction of the roll axis X. At least one jaw 134 may be formed to have a C-shaped cross-section when viewed from the direction of the roll axis X.

[0036] A second embodiment of the engine unit and variable area exhaust nozzle is shown in Figure 2b. Figure 2b substantially corresponds to the embodiment in Figure 2a. Therefore, in Figure 2b, similar parts are numbered with the same reference numerals as in Figure 2a plus 100. For example, the closed position 238 shown in Figure 2b corresponds to the closed position 138 shown in Figure 2a. Furthermore, the engine unit 206 and variable area exhaust nozzle 230 are described below only in cases where they differ from the variable area exhaust nozzle 130 and engine unit 106 of the first embodiment in Figure 2a, and all other features and functions refer to the description of the first embodiment.

[0037] The engine unit 206 includes an engine housing 212 extending from an inlet section 214 to an exhaust section 216. Furthermore, the engine housing 212 houses a rotor 222 having rotor blades 224 and stator blades 226.

[0038] A variable-area exhaust nozzle 230 is positioned adjacent to the engine housing 212. The variable-area exhaust nozzle 230 includes a jaw device 232. The jaw device 232 has at least one jaw 234 that is movable around a jaw pivot axis 234a. This jaw pivot axis 234a may be positioned in the lateral direction Y.

[0039] According to the second embodiment, the jaw device may have two jaws 234 that are close to each other in the closed position 238 shown by the dashed line, with a closed distance or cruising exhaust nozzle region 238a formed between them. The jaw device 232 in the open position 236 shown by the solid line forms an open distance or hovering exhaust nozzle region 236a between the two jaws 234. At least one jaw 234 may have a substantially trapezoidal shape when viewed from the lateral direction Y.

[0040] The exhaust nozzle regions 238a and 236a are determined by the shape and distance d of the cross-section of the variable-area exhaust nozzle. The variable-area exhaust nozzle 230 may have a rectangular cross-section when viewed from the direction of the roll axis X.

[0041] Figures 3a and 3b show a third embodiment of the variable area exhaust nozzle, substantially corresponding to the first and second embodiments of Figures 2a and 2b. Accordingly, in Figures 3a and 3b, similar parts are numbered with 200 added to the same reference numeral as in Figure 2a, and with 100 added to the reference numeral for parts in Figure 2b (for example, jaw pivot axis 334a is similar to jaw pivot axis 134a and jaw pivot axis 234a, aircraft 300 is similar to aircraft 100, and engine unit 306 is similar to engine unit 106). Furthermore, the variable area exhaust nozzle 330 will be described below only if it differs from the variable area exhaust nozzle 130 in Figure 2a and the variable area exhaust nozzle 230 in Figure 2b.

[0042] The jaw device 332 of the third embodiment includes at least one jaw portion 334 attached by a mounting portion 340 to the exhaust portion 316 of the engine 310 or to the engine housing 312. The mounting portion 340 may be a hinge, a link mechanism, or the like. The at least one jaw portion 334 is movable between an open position 336, shown by a dashed line, and a closed position 338, shown by a solid line.

[0043] Referring to Figures 3a and 3b, in the cruising position 306a, the thrust direction TH of the engine 310 may be parallel to the direction of travel X or the roll axis, or it may be inclined at an angle of less than 15 degrees with respect to the direction of travel X or the roll axis. Furthermore, in the hovering position 306b, the thrust direction TV of the engine 310 may be parallel to the vertical direction Z, or it may be inclined at an angle of less than 15 degrees with respect to the vertical axis Z. When the engine 310 rotates from the cruising position 306a to the hovering position 306b, at least one jaw section 334 moves from the closed position 338 to the open position 336.

[0044] The engine 310 is movable relative to the aircraft component 342 around the engine pivot axis 344. The movement of the engine 310 may be driven by a motor (not shown) in a well-known manner.

[0045] A transmission 350 is provided, comprising linking means 356 and a cam mechanism 358, to convert the motion of the engine 310 into the motion of at least one jaw 334. For example, the linking means 356 is a rod, and the cam mechanism 358 is a slotted cam. The transmission 350 is connected to the jaw device 332 at a first end 352 and to an aircraft component 342 at a second end 354. The aircraft component 342 may be the airfoil 302 of the aircraft 100.

[0046] At the second end 354, the link mechanism 356 is connected to the aircraft component 342 by a hinge joint at an offset distance 362 with respect to the engine pivot axis 344. The link mechanism 356 is connected to the cam mechanism 358 by another hinge joint. The cam mechanism 358 is connected to at least one jaw portion 334. The cam mechanism 358 is movable about a cam axis 366, indicated by a dashed cross.

[0047] The engine 310 is movable approximately 90° relative to the aircraft component 342 between the hovering position shown in Figure 3b and the cruising position shown in Figure 3a. When the engine 310 moves around the engine pivot axis 344, the linkage means 356 also moves. Due to the hinge joint, when the engine 310 rotates, the cam mechanism 358 rotates around the camshaft 366.

[0048] According to a third embodiment, the cam mechanism 358 comprises a slotted cam 370 and a pin 364a that engage with each other. The pin 364a is fixedly connected to the jaw assembly 332. When the slotted cam 370 moves, the pin 364a moves according to the shape of the slot in the slotted cam 370. This movement causes the jaw assembly 332 and at least one jaw 334 to move. During the manufacture of the engine, the shape of the slot may be designed by, for example, rotating the jaw 334 (e.g., by simulation or geometric calculation) to a desired angle relative to each position of the engine between cruising mode and hovering mode, and determining the corresponding path of the pin 364a to define the path of the slot. During operation, when the engine is orbiting, the pin 364a is forced to follow this path.

[0049] The cam mechanism 358, and in particular the slot of the slotted cam 370, may comprise a first portion 372a having a first shape that defines a first transmission ratio, and a second portion 372b having a second shape that defines a second transmission ratio. The movement of the pin 364a within the first portion 372 can make the movement of the jaw 334 faster, and the movement of the pin 364a within the second portion 372b can make the movement of the jaw 334 slower. As far as the movement of the engine 310 relative to the aircraft component 342 is concerned, for example, a first range in or near the cruising position in which the jaw 334 opens and closes relatively quickly, and a second range in or near the hovering position in which the jaw 334 opens and closes relatively slowly. As a result, the speed at which the jaw 334 moves is not strictly linear with respect to the engine's movement and may vary depending on the engine's position. Therefore, the exhaust nozzle region is determined with respect to the engine angle β between the aircraft component 342 and the engine 310, depending on the opening angle α of the jaw portion 334.

[0050] Furthermore, the slot of the slotted cam 370 may have a third portion (not shown) in which the slot follows a circular cross-section of a constant radius centered on the cam shaft 366. This prevents the relative motion between the slotted cam 370 and the pin 364a within the circular cross-section from being translated into the movement of the pin 364a around the jaw axis 334a, thus keeping the angular position of the jaw 334 fixed relative to the engine 310. In other words, as long as the pin 364a moves within the third portion of the slot, the movement of the engine 310 relative to the aircraft component 342 is not translated into the movement of the jaw 334.

[0051] The jaw assembly 332 may comprise a plurality of jaws, for example, two jaws 334b ​​and 334c. These jaws 334b ​​and 334c may be connected to each other by a link mechanism 380. The link mechanism 380 may be hinges fixed to the jaws 334b ​​and 334c. The movement of one jaw 334b ​​is transmitted via the link mechanism 380 to at least one of the other jaws 334c. Thus, both jaws 334b ​​and 334c move, for example, from a closed position 338 to an open position 336, in accordance with and driven by the movement of the engine 310. The movement of the two jaws 334b ​​and 334c may be essentially simultaneous. Alternatively, the two jaws 334b ​​and 334c may be opened and closed alternately.

[0052] Figure 4a shows a fourth embodiment of the variable area exhaust nozzle that substantially corresponds to the third embodiment in Figures 3a and 3b. Therefore, in Figure 4a, similar parts are numbered with 100 added to the same reference numerals as in Figures 3a and 3b (for example, engine 410 is similar to engine 310). Furthermore, the variable area exhaust nozzle 430 is described below only in cases where it differs from the variable area exhaust nozzle 330 in Figures 3a and 3b; for all other features and functions, refer to the description of the third embodiment.

[0053] Modifications of the fourth embodiment are shown in Figures 4b and 4c. Modifications of the fourth embodiment relate to the transmission concept illustrated and described with respect to Figure 4a. Therefore, the reference numerals in Figures 4b and 4c are mainly similar to those in Figure 4a, but with the addition of apostrophes (e.g., engine 410'). Figures 4a and 4b show engines 410 and 410' viewed from the lateral direction Y, and Figure 4c is a perspective view of engine 410'.

[0054] In Figure 4a, the jaw device 432 is attached to the exhaust section 416 of the engine 410 at the mounting section 440. A transmission 450 is associated with a variable-area exhaust nozzle 430 to control the movement of the jaw device 432, which has at least one jaw 434, and to convert the movement of the engine 410 into the movement of at least one jaw 434. As a result, the movement of the variable-area exhaust nozzle 430 is directly linked to the movement of the engine 410. The engine 410 may be rotated from a hovering position (not shown) substantially in the vertical thrust direction to a cruising position in a thrust direction TH substantially parallel or nearly parallel to the direction of travel X.

[0055] The first end 452 and the second end 454 of the transmission are connected to each other by a linkage means 456. The transmission is connected at the first end 452 by a hinge joint to at least one jaw 434, specifically the first jaw 434b of the jaw device 432. Each jaw 434 is movable about a jaw pivot axis 434a oriented in the lateral direction Y. In Figure 4a, the transmission 450 is connected to the first jaw 434b at a jaw offset distance 492 with respect to the jaw pivot axis 434a.

[0056] The transmission 450 is connected to an aircraft component at a second end 454 by a cam mechanism 458. The cam mechanism 458 may consist of a slotted cam that engages with an actuation pin connected to a linkage means 456 and is fixed to the aircraft component. Furthermore, the cam mechanism 458 is positioned around the engine pivot axis 444.

[0057] As shown in Figure 4a, when the engine 410 rotates from the cruising position to the hovering position or vice versa, the linkage means 456 moves at the second end 454, guided by the cam mechanism 458 around the engine rotation axis 444. Due to the jaw offset distance 492 between the first end 452 of the transmission 450 and the jaw rotation axis 434a, the movement of the engine 410 is converted into movement of the first jaw 434b around the jaw rotation axis 434a.

[0058] To convert this movement to at least one other jaw portion 434c, the first jaw portion 434b and at least one other jaw portion 434c are connected to each other by a link mechanism 480. According to a fourth embodiment, this link mechanism 480 may be a slotted cam mechanism 484. Thus, an actuating pin 486 is attached to the first jaw portion 434b protruding into at least one other jaw portion 434c. The actuating pin 486 may be integrally connected to the first jaw portion 434b. A slot of the slotted cam mechanism 484 is provided in at least one other jaw portion 434c. The actuating pin 486 engages with the slot of the slotted cam mechanism 484. The slot may be formed as an inclined curve to rotate the jaw portions 434b, 434c in opposite directions to open and close the jaw device 432. Of course, the first jaw portion 434b may be provided with a slot for a slotted cam mechanism 484, and at least one other jaw portion 434c may be provided with an operating pin 486.

[0059] Compared to Figure 4a, Figures 4b and 4c show alternative jaw designs and further identify a cam mechanism 458' including the interaction between the transmission 450' associated with the variable-area exhaust nozzle 430' and the aircraft component 442' during the rotational motion of the engine 410'. Compared to the jaw 434 shown in Figure 4a, the jaws 434b' and 434c' of the jaw device 432' may be substantially shorter in length in the direction of travel X, thereby reducing the weight of the jaws 434b' and 434c'. Combined with the chamfered shape of the jaw 434', the aerodynamic cross-section of the exhaust portion of the engine 410' can be further optimized. The alternative jaw designs shown in Figures 4b and 4c may also be applied to other embodiments, and the corresponding engine 410' may be equipped with the jaw 434 shown in Figure 4a.

[0060] Each engine 410' is rotatably engaged with an aircraft component 442' via a connection 446', for example, two connection 446', and is configured to control the rotational motion of the engine 410' about an engine pivot axis 444' by a common axis (not shown). In addition to a first link means 456a' that connects the transmission 450' to a jaw device 432', specifically the jaw 434b', via a first end 452', a second link means 456b' may be provided. Such a second link means 456b', shorter than the first link means 456a', is rotatably connected to a connection 446' of the aircraft component 442' at a second end 454' via a pin 462', thereby rotatable the second link means 456b' in accordance with the rotational direction of the engine 410'. The cam mechanism 458' is positioned between the first and second linkage means 456a', 456b' and is rotatably fixed to the engine 410' by the camshaft 466'.

[0061] The first and second linking means 456a', 456b', connected to the slotted plate of the cam mechanism 458' via first and second intermediate ends 460a', 460b', respectively, are substantially aligned with respect to the main extending direction and maintain this alignment even while the engine 410' is rotating. A pin 470' attached to the first linking means 456a' at the first intermediate end 460a' is guided by the guide path 468' of the cam mechanism 458'. When the engine 410' rotates relative to the aircraft component 442', i.e., when moving from a cruising position to a hovering position or vice versa, the slotted cam rotates around the camshaft 466', but its orientation may remain substantially constant relative to the aircraft component 442'.

[0062] The rotational motion of engine 410' and the rotation of the slotted cam around its camshaft 466' initiate the relative movement of pin 470' at the first intermediate end 460a' of the first linking means 456a' along a predefined path of guide path 468'. This path is arranged so that pin 470' moves in accordance with the rotational direction of engine 410' and traverses first, second, and third angular ranges of guide path 468'. With respect to the total angular range between a cruising position, which is similar to the engine 410' being positioned substantially parallel to the thrust direction TH, and a hovering position, where engine 410 is aligned substantially vertically, the first angular range may be defined as 0° to 30°, the second angular range as 30° to 60°, and the third angular range as 60° to 90°, and the third angular range may be extended up to 120°.

[0063] In the closed position 438' shown in Figures 4b and 4c, the distance of the guide path 468' to the camshaft 466' is shortest in the first angular range, but the corresponding distance gradually increases in the second angular range. As a result, while the pin 470' traverses the second angular range, the pin 470' and the first linkage means 456a' are gradually pushed toward the rear of the engine 410', i.e., toward the jaw device 432'. In the third angular range, the distance from the guide path 468' to the camshaft 466' is maximum, so the pin 470' is furthest from the camshaft 466' while in the third angular range.

[0064] As the distance of the pin 470' and the first linkage means 456a' to the camshaft 466' gradually changes within a second angular range of the guide path 468', the movement of the first linkage means 456a' is converted into the movement of the jaw 434b' at the first end 452', i.e., from the closed position 438' to the open position or vice versa. Thus, the movement of the jaw 434b' is governed by the pivoting motion of the engine 410'. A linkage mechanism 480' is used to convert the movement of the jaw 434b' into the movement of the jaw 434c'. The linkage mechanism 480' may be configured to include a slotted cam mechanism 484 and a pin 486, as described in the third embodiment or in the linkage mechanism 480 shown in Figure 4a. Furthermore, the jaw 434' may be positioned to pivot around the jaw pivot axis 434a'. Instead of the jaw apparatus 432' shown in Figures 4b and 4c, the jaw 434b' may be connected to the transmission 450' at its first end 452' at the offset distance 492 shown in Figure 4a.

[0065] According to the modified configuration of the fourth embodiment shown in Figures 4b and 4c, the jaw device 432' remains in the closed position 438' during the first angular range, moves from the closed position 438' to the open position during the second angular range, and remains in the open position during the third angular range. Conversely, that is, when the engine 410' turns from the hovering position to the cruising position, the jaw device 432' remains in the open position during the third angular range, moves to the closed position 438' during the second angular range, and remains in the closed position 438' during the first angular range.

[0066] Figure 5 shows a fifth embodiment of the variable area exhaust nozzle that substantially corresponds to the third embodiment in Figures 3a and 3b. Therefore, in Figure 5, similar parts are numbered with the same reference numerals as in Figures 3a and 3b plus 200 (for example, engine 510 is similar to engine 310). Furthermore, the variable area exhaust nozzle 530 is described below only in cases where it differs from the variable area exhaust nozzle 330 in Figures 3a and 3b; for all other features and functions, refer to the description of the third embodiment.

[0067] The transmission 550 according to the fifth embodiment includes an elastic member 561, such as a spring, connected at a first end 552 to the jaw portion 534 of the jaw device 532 at an offset distance 592 with respect to the jaw pivot axis 534a. The elastic member 561 is connected at a second end 554 to an aircraft component 542 (corresponding to an aircraft component 342, not shown) at an offset distance 562 with respect to the engine pivot axis 544.

[0068] A mechanical stop 594 is provided to fix the position of the jaw 534. When the engine rotates within the idle range, the jaw 534 is held in contact with the mechanical stop 594 by the elastic member 561, while the elastic member 561 is compressed or stretched. Therefore, when the engine 510 rotates around the engine pivot axis 544 within a first angular range, the transmission 550 transmits the movement of the engine 510 relative to the aircraft component 542 to the jaw 534 in order to rotate the jaw 534. In contrast, when the engine 510 rotates around the engine pivot axis 544 within a second angular range (idle range), the position of the jaw 534 relative to the engine 510 is fixed.

[0069] The engine 510 may further include an elastic means 565 for pre-tensioning the jaw portion 534 toward an open or closed position 538. The elastic means 565 is connected to at least one jaw portion 534 at a first end 565a. The elastic means 565, which may be a tension spring, is connected to the engine housing portion 512a at a second end 565b.

[0070] For example, the elastic means 565 pre-tensions the jaw 534 in the closed position 538. The engine 510 may rotate downward from a cruising position where the jaw 534 is in the closed position 538 to a hovering position where the jaw 534 is in the open position. Initially, the engine 510 moves within an idle range where the jaw 534 remains in the closed position 538. The engine then moves within a first range, and the elastic means 565 is stretched. As a result, the jaw 534 opens in response to the movement of the engine 510 until it reaches its maximum open position.

[0071] Figures 6a and 6b show a sixth embodiment of the variable area exhaust nozzle that substantially corresponds to the third embodiment in Figures 3a and 3b. Accordingly, in Figures 6a and 6b, similar parts are numbered with 300 added to the same reference numerals as in Figures 3a and 3b (for example, engine 610 is similar to engine 610). Furthermore, the variable area exhaust nozzle 630 is described below only in cases where it differs from the variable area exhaust nozzle 330 in Figures 3a and 3b, and for all other features and functions, refer to the description of the third embodiment.

[0072] A sixth embodiment includes a transmission 650, which comprises a pulley transmission 667. The pulley transmission 667 may have a first pulley 669 connected to the jaw pivot axis 634a of the jaw 634 of the jaw device 632, and another second pulley 671 connected to the engine pivot axis 644 toward the engine 610, and is movable. The first pulley 669 and the second pulley 671 may be connected by at least one connecting means 673. Furthermore, the second pulley 671 may have a non-circular cross-section, preferably an elliptical cross-section including a small radius portion 671c and a large radius portion 671d.

[0073] According to the sixth embodiment, the first pulley 669 and the second pulley 671 are connected to a belt device 673, specifically a tension belt 673a and a slack belt 673b. The tension belt 673a and the slack belt 673b are fixed to each pulley 669, 671, specifically on opposite sides. For example, the slack belt 673b is connected to the first pulley 669 on its right side 669a and to the second pulley 671 on its left side 671b, while the tension belt 673a is connected to the left side 669b of the first pulley and to the right side 671a of the second pulley 671. As a result, the tension belt 673a and the slack belt 673b intersect each other at the intersection 675 between the first pulley 669 and the second pulley 671.

[0074] A belt tensioning device 679 that contacts the loose belt 673b may be provided to maintain the distance between the tensioned belt 673a and the loose belt 673b and to accommodate the loose portion of the loose belt 673b.

[0075] In the cruising position shown in Figure 6a, the second pulley 671 is oriented such that its small radius portion 671c faces the first pulley 669. When the engine 610 is rotated relative to the aircraft component 642 (not shown) around the engine pivot axis 644 toward the hovering position (Figure 6b), the first pulley 669 rotates with the engine around the engine pivot axis 644, but the second pulley 671 does not follow this rotation because it is fixed to the aircraft component. As a result, the largest diameter portion 671d of the second pulley 671 faces the first pulley 669. Consequently, tension is applied to the tension-side belt 673a, and the slack-side belt 673b is discharged, causing the first pulley 669 to rotate relative to the engine. This causes the jaw portion 634 to move from the closed position 638 to the open position 636.

[0076] Instead of using the tension belt 673a and the slack belt 673b, the above configuration may use a single continuous belt that surrounds and frictionally engages both pulleys 669 and 671. In further variations of the embodiment, instead of one or two belts, one continuous or two separate cables, chains, or other longitudinally elongated transmission members may be used.

Claims

1. An engine for a vertical takeoff and landing aircraft, wherein the engine is configured to move relative to the aircraft components of the aircraft between a hovering position for takeoff and landing and a cruising position for forward flight, the engine comprises a variable-area exhaust nozzle attached to the exhaust portion of the engine, and the variable-area exhaust nozzle comprises at least one aerodynamic element that is movable relative to the engine between an open position and a closed position. The engine comprises a mechanical transmission, the mechanical transmission having a first end connected to the at least one aerodynamic element and a second end configured to be connected to the aircraft component, the mechanical transmission being configured to directly convert the movement of the engine relative to the aircraft component into the movement of the at least one aerodynamic element.

2. The engine according to claim 1, wherein the mechanical transmission is configured to set the aerodynamic element to the open position when the engine takes the hovering position, and to set the aerodynamic element to the closed position when the engine takes the cruising position.

3. The engine according to claim 1 or claim 2, wherein the aircraft component is an airfoil or the fuselage of an aircraft, or a component fixed to the airfoil or the fuselage of an aircraft.

4. The engine according to any one of claims 1 to 3, wherein the range of motion of the engine relative to the aircraft component between a hovering position and a cruising position includes a first range and a second range, and the mechanical transmission is configured to have a first transmission ratio when the engine is moving within the first range and a second transmission ratio lower than the first transmission ratio when the engine is moving within the second range.

5. The engine according to any one of claims 1 to 4, wherein the range of motion of the engine relative to the aircraft component between a hovering position and a cruising position includes an idle range, and the movement of the engine within the idle range is not converted into the movement of the aerodynamic elements.

6. In the idle range, the aerodynamic element or the mechanical transmission remains in contact with a mechanical stop for fixing the position of the aerodynamic element relative to the engine, and / or The engine according to claim 5, wherein the mechanical transmission includes an elastic member arranged to adjust the movement of the engine relative to the aircraft component to within the idle range so that the movement of the engine is not converted into the movement of the variable-area exhaust nozzle.

7. The engine according to any one of claims 1 to 6, wherein the mechanical transmission comprises linkage means.

8. The engine according to claim 7, wherein the link means comprises a rod and / or a cam mechanism.

9. The engine according to claim 8, wherein the cam mechanism comprises a slotted cam.

10. The engine according to any one of claims 1 to 9, wherein the aerodynamic element is biased by an elastic member toward a first position or toward a second position.

11. The engine according to any one of claims 1 to 10, wherein the mechanical transmission comprises a pulley transmission.

12. The engine according to claim 11, wherein the pulley transmission comprises at least a first pulley connected to the aerodynamic element, a second pulley configured to be connected to or fixed to an aircraft component, and a belt for transmitting the movement of one of the first pulley and the second pulley to the other of the first pulley and the second pulley.

13. The engine according to claim 12, wherein at least one of the first pulley and the second pulley has a non-circular cross-section.

14. The engine according to any one of claims 1 to 13, wherein the variable area exhaust nozzle comprises a first aerodynamic element and a second aerodynamic element, the first aerodynamic element and the second aerodynamic element being connected to each other by a link mechanism.

15. The engine according to claim 14, wherein the link mechanism comprises a link and / or a slotted cam, so that the movement of the first aerodynamic element drives the movement of the second aerodynamic element.

16. The engine according to any one of claims 1 to 15, wherein the at least one aerodynamic element is a baffle plate or jaw portion of a variable-area exhaust nozzle configured to deflect the exhaust flow of the engine and define the exhaust region of the engine.

17. The engine according to any one of claims 1 to 16, wherein the engine is an electric engine or an electrically ducted fan.

18. A vertical takeoff and landing aircraft comprising an aircraft component and an engine according to any one of claims 1 to 17.

19. A vertical takeoff and landing aircraft according to claim 18, comprising an airfoil and a plurality of engines mounted on the airfoil in a row adjacent to each other.

20. The vertical takeoff and landing aircraft according to claim 19, comprising more than five engines or more than ten engines.

21. The vertical takeoff and landing aircraft according to claim 19 or 20, wherein each of the engines is capable of rotating independently of the other engines relative to the airfoil.

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