A transmission system for a coaxial twin rotor

Abstract

This invention discloses a transmission system for a coaxial twin-rotor tip jet aircraft, comprising a main drive shaft system, a lower rotor drive shaft system, a drive shaft system, a follower shaft system, an overrunning clutch assembly, a hot gas delivery assembly, and a cold gas delivery assembly. The overrunning clutch assembly connects to the engine and transmits the engine's power to the drive shaft system during initial startup. The drive shaft system then transmits power to the main drive shaft system and the lower rotor drive shaft system. The main drive shaft system drives the upper rotor, and the lower rotor drive shaft system drives the lower rotor, causing the upper and lower rotors to rotate in opposite directions at the same speed. After the upper and lower rotors reach a certain speed, the overrunning clutch assembly automatically disengages and cuts off the engine's power input. This invention achieves speed reduction and torque increase, simplifies the transmission mechanism, reduces the weight of the transmission mechanism, improves its power-to-weight ratio, and ensures that the upper and lower rotors can rotate in opposite directions at the same speed, balancing the speed difference between the upper and lower rotors.

Description

Technical Field

[0001] This invention relates to the field of coaxial twin-rotor tip jet propulsion systems, and more particularly to a propulsion system that achieves constant-speed, reverse-rotation of coaxial twin rotors in a tip jet system through a planetary gear structure. Background Technology

[0002] Coaxial twin-rotor aircraft are aircraft that use two coaxial counter-rotating rotors, one above the other. By changing the counter-torque of the two rotors, directional control is achieved. They do not require a tail rotor, which greatly reduces the overall weight of the aircraft. At the same time, eliminating the tail rotor saves a lot of space and has low requirements for infrastructure. They have great advantages in the future urban transportation field. They also have advantages such as vertical take-off and landing, hovering, and rapid turning, so they are widely used in rescue and civilian fields and are the main players in the "low-altitude economy".

[0003] Traditional coaxial twin-rotor aircraft transmission systems typically employ two shaft systems: an inner shaft and an outer shaft. The inner shaft drives one rotor, while the outer shaft, mounted on the inner shaft, drives the other rotor. The shaft power generated by the engine drives the two shaft systems to rotate in opposite directions at the same speed through the transmission system. Based on the gear units and structures used to achieve coaxial or counter-rotating transmission in the final drive stage, coaxial twin-rotor aircraft transmission system configurations can be categorized into three main types: simple gear transmission systems, fixed-axis transmission systems, and compound gear transmission systems.

[0004] Tip-jet aircraft generate lift for their rotors by using the counter-torque created by the high-pressure, high-speed airflow ejected from the rotor tip. Their application value has long attracted research and exploration from relevant institutions and scholars both domestically and internationally. Although their development history spans nearly 80 years, the principle of using a single power system as the air source generator to power the rotor has consistently failed to meet the diverse performance requirements of aircraft. In recent years, with the continuous advancement of micro-engine technology in aviation and the rapid development of the low-altitude economy, the development of a new tip-jet propulsion system is crucial for solving a series of core technologies and for promoting the rapid development of the low-altitude economy.

[0005] In existing technologies, there are no examples of using coaxial twin-rotor drives in tip-jet systems. Tip-jet systems, combined with a coaxial twin-rotor structure, generate lift and thrust by using the reaction force produced when bleed air from inside the rotor is expelled through the tip nozzle. During operation, the airframe does not generate reverse torque. Furthermore, to meet the requirements of tip-jet systems, hot air must be delivered to the rotor tip. Traditional transmission systems do not need to consider hot air delivery and are therefore unsuitable for tip-jet systems. Moreover, traditional coaxial twin-rotor transmission systems require multiple gear pairs or bevel gears to achieve uniform counter-rotation of the rotors. While bevel gears can reduce the rotor speed to the required level, sometimes multiple reduction gears are also needed, resulting in a complex, bulky, and inefficient transmission mechanism. Therefore, there is an urgent need to design a coaxial twin-rotor transmission system that can be used in tip-jet systems.

[0006] To meet the requirement of equal-speed, counter-rotating upper and lower rotors in coaxial twin-rotor aircraft and overcome the shortcomings of poor reliability and low transmission efficiency in existing transmission devices, the following solutions have been provided by existing technologies: Chinese Patent CN111268113B, entitled "Bevel Gear Configuration Coaxial Twin-Rotor Speed ​​Transmission Mechanism," provides a bevel gear configuration coaxial twin-rotor speed transmission mechanism, which includes a staged reduction device and a coaxial reduction device. In this structure, the upper bevel gear is fixed to the lower rotor via an output shaft, while the lower bevel gear is first fixed to the upper rotor via a planetary reduction mechanism to achieve counter-rotating dual rotors. However, the use of the staged reduction device and bevel gears still makes the structure relatively complex and heavy. In summary, the planetary gear configuration transmission mechanism in existing coaxial twin-rotor technology remains relatively complex and heavy, and the multi-stage reduction still results in low transmission efficiency. Summary of the Invention

[0007] To address the aforementioned problems in the prior art, this invention provides a transmission system that enables coaxial dual rotors of a propeller tip jet system to rotate at the same speed and in opposite directions using a planetary gear structure. By utilizing two sets of gears, the coaxial dual rotors can rotate at the same speed, reducing the weight of the transmission mechanism, improving transmission efficiency, and fulfilling the requirement of transmitting hot air to the propeller tip.

[0008] The complete technical solution of this invention includes: A transmission system for a coaxial twin-rotor tip-jet aircraft is disclosed. The transmission system is applied to the coaxial twin-rotor aircraft and is a transmission system that realizes the constant speed and reverse direction of the coaxial twin rotors of the tip-jet system through a planetary gear structure. It is applied to the power source generated by the tip-jet. In the initial stage of startup, only a small-power piston engine is needed to drive the rotor to rotate. After reaching a certain speed, the power of the small-power piston engine is disconnected through a clutch. Subsequently, the gas generated by the gas turbine is used as a flexible power source to drive the rotor to rotate.

[0009] The aircraft comprises a coaxial upper rotor and a lower rotor. Initially, the engine drives the rotor to rotate. Once a certain speed is reached, the engine power is disconnected, and the aircraft is powered by exhaust gas, employing a tip-jet propulsion system. The high-pressure, high-speed airflow ejected from the propeller tips creates a counter-torque that drives the rotor to rotate and provides lift. The transmission system includes a main drive shaft system, a lower rotor drive shaft system, a drive shaft system, a follower shaft system, an overrunning clutch assembly, a hot air supply assembly, and a cold air supply assembly. The overrunning clutch assembly connects to the engine and transmits the engine's power to the drive shaft system during the initial startup phase. The drive shaft system then transmits the power to the main drive shaft system and the lower rotor drive shaft system. The main drive shaft system drives the upper rotor, and the lower rotor drive shaft system drives the lower rotor, causing the upper and lower rotors to rotate in opposite directions at the same speed. Once the upper and lower rotors reach a certain speed, the overrunning clutch assembly automatically disengages and cuts off the engine's power input. When the upper and lower rotors drop below a certain speed, the engine disconnects its power, and the overrunning clutch assembly automatically engages the engine's power input and transmits power to the drive shaft system. When there is a phase difference between the upper and lower rotors, the phase difference between the upper and lower rotors is kept consistent through the drive shaft and the follower shaft.

[0010] Furthermore, the overrunning clutch assembly 5 includes an overrunning clutch connecting flange 51, an overrunning clutch housing 53, a star wheel 57, an adjustment shaft 58, rollers 59, and a spring pin assembly 510. Star wheel 57 is connected to adjustment shaft 58 by a flat key. Overrunning clutch housing 53 is fitted on star wheel 57 with a partial gap. Star wheel 57 has a wedge slot. A transverse gap is left on one side of the wedge slot to place spring pin assembly 510, and a roller 59 is placed on the other side. In the initial stage of startup, a piston engine is used as the power source input. The power of the piston engine is first received by the adjusting shaft 58, which drives the star wheel 57 to rotate at a constant speed. Under the action of friction, the roller 59 is wedged between the overrunning clutch housing 53 and the star wheel 57, thereby transmitting power to the overrunning clutch connecting flange 51. When the rotational speed of the overrunning clutch connecting flange 51 is greater than the rotational speed of the adjusting shaft 58, the roller 59 is released from the wedged gap and disengages from the overrunning clutch housing 53. The power of the adjusting shaft is no longer transmitted to the overrunning clutch connecting flange 51.

[0011] Furthermore, the drive shaft system includes a drive shaft idler wheel 31, a lower rotor drive gear 32, a drive shaft 36, and an upper rotor drive gear 38; The upper rotor drive gear 38 and the lower rotor drive gear 32 are connected to the drive shaft 36 by a key. The drive shaft 36 is connected to the overrunning clutch connecting flange 51 by a flat key and screws. The drive shaft idler 31 meshes with the lower rotor drive gear 32 once. In the initial stage of startup, the overrunning clutch connecting flange 51 drives the drive shaft 36 to rotate at a constant speed, thereby transmitting power to the upper rotor drive gear 38 and the lower rotor drive gear 32. The lower rotor drive gear 32 then achieves the drive shaft idler gear 31 to rotate in the opposite direction at a constant speed through a single engagement with the drive shaft idler gear 31.

[0012] Furthermore, the main drive shaft system includes: a main drive shaft 16 and a main shaft driven gear 19, the main shaft driven gear 19 being connected to the main drive shaft 16; In the initial stage of startup, the driven gear 19 of the main shaft meshes with the drive gear 38 of the upper rotor, transmitting power to the main drive shaft 16, thereby transmitting power in reverse to the upper rotor.

[0013] Furthermore, the lower rotor drive shaft system 2 includes a lower rotor drive shaft 25 and a lower rotor driven gear 26; The driven gear 26 of the lower rotor is welded to the drive shaft 25 of the lower rotor. In the initial stage of startup, the power on the drive shaft 36 is output in the same direction through two meshings between the drive gear 32 of the lower rotor, the idler gear 31 of the drive shaft, and the driven gear 26 of the lower rotor, and then transmitted to the lower rotor through the drive shaft 25.

[0014] Furthermore, the follower shaft system includes a follower shaft idler gear 41, a lower rotor follower gear 42, a follower shaft 46, and an upper rotor follower gear 48. The upper rotor follower gear 48 and the lower rotor follower gear 42 are connected to the follower shaft 46 by a key. In the initial stage of startup, the upper rotor follower gear 48 meshes with the main shaft driven gear 19 to transmit power in the reverse direction to the follower shaft 46. The lower rotor follower gear 42, after meshing with the follower shaft idler gear 41 and the lower rotor driven gear 26 twice, transmits power in the same direction to the follower shaft 46.

[0015] Furthermore, in order to realize the propeller tip jet as a power source, the aircraft in question needs to consider the hot air input channel between the main drive shaft and the lower rotor drive shaft, and a certain space needs to be left between the main drive shaft and the lower rotor drive shaft as a hot air flow channel. Therefore, this transmission system also includes an inner tube upper base 63, an inner tube lower base 64, a hot air supply assembly 6 including a central hot air outer pipe 61 and a central hot air inner pipe 62, and a cold air supply assembly 7 including an outer cold air outer pipe 71; The central hot air outer pipe 61 and the central hot air inner pipe 62 are both welded to the inner pipe upper base 63, and the inner pipe upper base 63 and the outer cold air outer pipe 71 are both welded to the inner pipe lower base 64. Hot air inlet and cold air inlet are respectively opened on the central hot air outer pipe 61 and the external cold air outer pipe 71. Hot air flows in the flow channel between the central hot air outer pipe 61 and the central hot air inner pipe 62, and cold air flows in the flow channel between the central hot air outer pipe 61 and the external cold air outer pipe 71. Cold air also flows in the main drive shaft 16 at the same time.

[0016] The airflow inlet in the transmission system is located above the driven gear of the main shaft. Hot air flows through the space between the main drive shaft and the lower rotor drive shaft to the upper and lower rotors. The driven gear of the lower rotor is designed as a hollow gear disk to provide space for the hot air flow channel. The hot air inlet is located above the driven gear of the main shaft, which is designed as a solid gear to prevent air leakage and reduce transmission efficiency.

[0017] Based on the above design, the driven gears of the main shaft and the lower rotor have more teeth and larger gear disk radii. Since the transmission ratio is equal to the ratio of rotational speeds and inversely proportional to the number of teeth, when the piston engine is used as the power source during initial startup, the speed at which the piston engine outputs power can be reduced, achieving deceleration and torque increase. Simultaneously, considering the required rotor speed during initial startup and the piston engine speed, a transmission ratio of 4 is more suitable. A transmission ratio that is too high would require even more teeth on the driven gears, resulting in excessively narrow tooth widths, which would be detrimental to the strength and rigidity of the gears.

[0018] Furthermore, the hot air comes from the gas turbine and is used to propel the rotor as a reverse thrust by being ejected from the blade tip, while the cold air is used to cool the components in the transmission mechanism that require cooling.

[0019] Furthermore, the number of teeth of the main shaft driven gear 19 and the lower rotor driven gear 26 is four times that of the idler gears of the drive shaft and follower shaft and the drive gears of the upper and lower rotors.

[0020] Furthermore, the coaxial twin-rotor tip jet aircraft with the aforementioned transmission system includes a piston engine-gas turbine composite power system, comprising a piston engine, a gas turbine, and a control system; the piston engine provides rotational power to the upper and lower rotors; the hot gas supplied by the gas turbine is ejected from the rotor tip through the hot gas delivery assembly 6, providing rotational power to the rotors; the gas turbine also provides high-pressure gas to the piston engine.

[0021] The working principle of the transmission system involved in this invention is as follows: During initial startup, power is output from a small-power piston engine and transmitted to the drive shaft via an overrunning clutch. The drive shaft then simultaneously rotates both the upper and lower rotor drive gears, while the drive shaft itself remains stationary. The overrunning clutch automatically adjusts its speed; when the rotor speed exceeds the power source speed, it disengages to cut off power input; when the rotor speed is lower than the power source speed, it engages to transmit power and maintain a stable rotor speed. The upper rotor drive gear is located near the overrunning clutch. Through gear transmission, power is transmitted to the upper rotor drive gear via the drive shaft. This gear engages with the driven gear on the main shaft, driving the rotation of the main drive shaft. The main drive shaft is connected to the upper rotor via an upper rotor connecting plate, thus driving the upper rotor to rotate.

[0022] Based on the relationship between transmission ratio, rotational speed, and number of teeth, the transmission ratio is equal to the ratio of rotational speeds, which is inversely proportional to the number of teeth. For the upper rotor drive gear and the main shaft driven gear, the number of teeth on the main shaft driven gear is greater than the number of teeth on the upper rotor drive gear. According to the above relationship, the rotational speed of the main shaft driven gear is lower than that of the upper rotor drive gear. This achieves the goal of reducing the output speed of the piston engine, thus meeting the requirement of reducing the rotational speed.

[0023] When power is transmitted from the drive shaft to the lower rotor drive gear, the lower rotor drive gear has the same number of teeth as the upper rotor drive gear. It transmits power in the same direction but at the same speed as the upper rotor through two external meshings: one with an idler gear of the same number of teeth, and the other with a lower rotor driven gear of the same number of teeth as the main shaft driven gear. The lower rotor is connected to the lower rotor drive shaft system via a lower rotor connecting flange. The speed output by the piston engine is also reduced on the lower rotor, achieving equal-speed, counter-rotating rotation of the upper and lower rotors. After the upper rotor follower gear meshes with the main shaft driven gear, it transmits power to the follower shaft, which is fixed. Simultaneously, the lower rotor driven gear transmits power to the follower shaft through two meshings: one with another idler gear and the other with the lower rotor follower gear. The coordinated use of the follower shaft system and the drive shaft system efficiently transmits power, improves the continuity and stability of the transmission, increases transmission efficiency, and balances the speed difference between the upper and lower rotors.

[0024] After startup, once the rotors have reached a certain speed, the piston engine power source is disengaged via the overrunning clutch. Hot gas from the gas turbine is then transferred through the flow channel between the main drive shaft and the lower rotor driven gear to the tips of both the upper and lower rotors. The hot gas is expelled from the tips as thrust, driving the rotors to rotate. The upper and lower rotors drive the main drive shaft and the lower rotor drive shaft to rotate, which in turn drives the main shaft driven gear and the lower rotor driven gear to rotate. The main shaft driven gear meshes with the upper rotor drive gear and the upper rotor follower gear, respectively, thus driving the drive shaft and follower shaft to rotate. Simultaneously, the lower rotor driven gear and its two idler gears mesh twice with the lower rotor drive gear and the lower rotor follower gear, transmitting power to the drive shaft and follower shaft. At this point, the power from the upper and lower rotors converges on the drive shaft and follower shaft. If there is a phase difference between the upper and lower rotors, the drive shaft and follower shaft can ensure that the phase difference is consistent, while also balancing the uneven thrust caused by the difference in jet volume between the upper and lower rotors. Therefore, the speed difference between the upper and lower rotors is also balanced, ensuring that the coaxial dual rotors achieve constant speed and opposite rotation.

[0025] The beneficial effects of this invention are as follows: 1. An invention provides a transmission structure for use in a propeller tip jet system, which enables the flow of hot air in the transmission mechanism. After leaving a hot air flow channel in the transmission mechanism, the driven gear of the main shaft and the driven gear of the lower rotor are designed as large discs, increasing the number of teeth on the two driven gears. At the same time, it reduces the speed output of the piston engine in the initial stage of start-up, achieving deceleration and torque increase. This simplifies the transmission mechanism, reduces its weight, improves its power-to-weight ratio, and ensures that the upper and lower rotors can achieve constant speed and opposite rotation, balancing the speed difference between the upper and lower rotors.

[0026] 2. When using tip jet propulsion as a flexible power source, both the upper and lower rotor tips emit jets as power input. The difference in jet volume may cause different rotational speeds between the upper and lower rotors. This planetary gear structure achieves the convergence of power between the upper and lower rotors on the drive shaft and follower shaft, ensuring a consistent phase difference between the upper and lower rotors. This balances the speed difference caused by the possible difference in jet volume and enables the upper and lower rotors to rotate in opposite directions at the same speed under these conditions.

[0027] 3. An overrunning clutch design is adopted. When the rotor speed is greater than the power source speed, the overrunning clutch can disengage and cut off the power input. When the rotor speed is less than the power source speed, the overrunning clutch can engage and transmit power to maintain a stable rotor speed.

[0028] 4. It has a simple structure, without complex multiple gear pairs, and achieves power transmission through only two sets of gear pairs, resulting in high transmission efficiency. Attached Figure Description

[0029] Figure 1 This is a front view of the transmission system used for tip jet propulsion in a coaxial twin rotor.

[0030] Figure 2 This is an isometric view of the transmission system used for tip jet propulsion in a coaxial twin rotor.

[0031] Figure 3 This is a cross-sectional view of a coaxial twin-rotor tip jet propulsion system.

[0032] Figure 4 This is a front view used to illustrate the jet flow path at the tip of a coaxial dual rotor.

[0033] Figure 5 This is a cross-sectional view used to illustrate the jet flow path at the tip of a coaxial twin rotor.

[0034] In the diagram, 1-Main drive shaft system, 11-Main drive shaft locking nut A, 12-Main drive shaft locking nut B, 13-Connecting disc sealing plate, 14-Connecting disc screw, 15-Upper rotor connecting disc, 16-Main drive shaft, 17-Main drive shaft sealing assembly A, 18-Main shaft driven gear connecting screw, 19-Main shaft driven gear, 110-Main drive shaft sealing assembly B, 2-Lower rotor drive shaft system, 21-Lower rotor connecting flange, 22-Lower rotor drive flange, 23-Lower rotor locking nut Nut, 24-Lower rotor brush seal, 25-Lower rotor drive shaft, 26-Lower rotor driven gear, 3-Drive shaft system, 31-Drive shaft idler gear, 32-Lower rotor drive gear, 33-Lower rotor drive gear mounting bolt, 34-Lower rotor drive gear washer, 35-Drive shaft bushing, 36-Drive shaft, 37-Upper rotor drive gear spacer, 38-Upper rotor drive gear, 39-Drive shaft cover, 310-Upper rotor drive gear deep groove ball bearing, 311-Lower rotor drive gear 4-Deep groove ball bearing for wheel, 4-Follower shaft system, 41-Follower shaft idler gear, 42-Lower rotor follower gear, 43-Lower rotor follower gear mounting bolt, 44-Lower rotor follower gear washer, 45-Follower shaft sleeve, 46-Follower shaft, 47-Upper rotor follower gear spacer, 48-Upper rotor follower gear, 49-Upper rotor follower gear washer, 410-Flange nut, 411-Upper rotor follower gear deep groove ball bearing, 412-Lower rotor follower gear deep groove ball bearing, 5-Overrunning clutch Assembly, 51-Overrunning clutch connecting flange, 52-Overrunning clutch rear cover, 53-Overrunning clutch housing, 54-Overrunning clutch front cover, 55-Deep groove ball bearing A, 56-Deep groove ball bearing B, 57-Star wheel, 58-Adjustment shaft, 59-Roller, 510-Spring pin assembly, 6-Hot air supply assembly, 61-Central hot air outer pipe, 62-Central hot air inner pipe, 63-Inner pipe upper base, 64-Inner pipe lower base, 7-Cold air supply assembly, 71-Outer cold air outer pipe. Detailed Implementation

[0035] The present invention will now be described in detail with reference to embodiments and accompanying drawings. However, it should be understood that the embodiments and drawings are for illustrative purposes only and do not constitute any limitation on the scope of protection of the present invention. All reasonable modifications and combinations included within the inventive spirit of the present invention fall within the scope of protection of the present invention.

[0036] This invention discloses a transmission system for tip jet propulsion in a coaxial twin-rotor rotor, such as... Figure 1 , Figure 4 As shown, it includes: main drive shaft system 1, lower rotor drive shaft system 2, drive shaft system 3, follower shaft system 4, overrunning clutch assembly 5, hot air supply assembly 6, and cold air supply assembly 7.

[0037] like Figure 2 , Figure 3 , Figure 4 , Figure 5 As shown, the overrunning clutch assembly 5 includes an overrunning clutch connecting flange 51, an overrunning clutch rear cover 52, an overrunning clutch housing 53, an overrunning clutch front cover 54, a deep groove ball bearing A 55, a deep groove ball bearing B 56, a star wheel 57, an adjustment shaft 58, rollers 59, and a spring pin assembly 510.

[0038] Star wheel 57 is connected to adjustment shaft 58 via a flat key. Deep groove ball bearings A55 and B56 are fitted onto the upper and lower ends of star wheel 57. Overrunning clutch housing 53 is fitted onto star wheel 57 with a partial gap. Star wheel 57 has three wedge slots. One side of the wedge slot has a lateral gap for placing spring pin assembly 510, and the other side is for placing roller 59. Overrunning clutch rear cover 52 and overrunning clutch front cover 54 are coaxially fitted with deep groove ball bearings A55 and B56 and installed at their front and rear. Overrunning clutch rear cover 52 is connected to overrunning clutch connecting flange 51 by screws and fixed to overrunning clutch housing 53 by the same screw. Overrunning clutch front cover 54 is connected to overrunning clutch housing 53 by screws.

[0039] In the initial startup phase, a piston engine is used as the power input. The power from the piston engine is first received by the adjusting shaft 58, which drives the star wheel 57 to rotate at a constant speed. Under the action of friction, the roller 59 is wedged between the overrunning clutch housing 53 and the star wheel 57, thereby transmitting power to the overrunning clutch connecting flange 51. When the rotational speed of the overrunning clutch connecting flange 51 is greater than the rotational speed of the adjusting shaft 58, the roller 59 is released from the wedged gap and disengages from the overrunning clutch housing 53. The power from the adjusting shaft is then no longer transmitted to the overrunning clutch connecting flange 51. Through this overrunning clutch assembly, it is possible to achieve the following in this invention: when the rotor speed is greater than the power source speed, the overrunning clutch can disengage; when the rotor speed is less than the power source speed, the overrunning clutch can engage to transmit power, maintaining a stable rotor speed.

[0040] like Figure 2 , Figure 3 , Figure 4 As shown, the drive shaft system 3 includes a drive shaft idler wheel 31, a lower rotor drive gear 32, a lower rotor drive gear mounting bolt 33, a lower rotor drive gear washer 34, a drive shaft bushing 35, a drive shaft 36, an upper rotor drive gear spacer 37, an upper rotor drive gear 38, a drive shaft cover 39, an upper rotor drive gear deep groove ball bearing 310, and a lower rotor drive gear deep groove ball bearing 311.

[0041] The upper rotor drive gear 38, the upper rotor drive gear deep groove ball bearing 310, the lower rotor drive gear deep groove ball bearing 311, and the lower rotor drive gear 32 are coaxially sleeved on the drive shaft 36. The upper rotor drive gear 38 and the lower rotor drive gear 32 are connected to the drive shaft 36 by a key. The lower rotor drive gear 32 is coaxially fitted with the lower rotor drive gear washer 34 on the drive shaft 36 and then connected to the drive shaft 36 by the lower rotor drive gear mounting bolt 33. The drive shaft sleeve 35 is fitted on the drive shaft 36 after cooperating with the upper rotor drive gear deep groove ball bearing 310 and the lower rotor drive gear deep groove ball bearing 311, thus realizing the protection function of the sleeve. The upper rotor drive gear spacer 37 is fitted on the drive shaft 36 and located above the upper rotor drive gear 38. The drive shaft 36 is connected to the overrunning clutch connecting flange 51 by a flat key and screws.

[0042] In the initial stage of startup, the overrunning clutch connecting flange 51 drives the drive shaft 36 to rotate at a constant speed, thereby transmitting power to the upper rotor drive gear 38 and the lower rotor drive gear 32. The lower rotor drive gear 32 then achieves the drive shaft idler gear 31 to rotate in the opposite direction at a constant speed through a single engagement with the drive shaft idler gear 31.

[0043] like Figure 2 , Figure 3 As shown, the main drive shaft system 1 includes: main drive shaft locking nut A11, main drive shaft locking nut B12, connecting disc sealing plate 13, connecting disc screw 14, upper rotor connecting disc 15, main drive shaft 16, main drive shaft sealing assembly A17, main shaft driven gear connecting screw 18, main shaft driven gear 19, and main drive shaft sealing assembly B110.

[0044] The connecting disc sealing plate 13 is fitted onto the main drive shaft 16. The upper rotor connecting disc 15 is connected to the connecting disc sealing plate 13 by the connecting disc screw 14. At the same time, the upper rotor is fixed to the upper rotor connecting disc 15 by the connecting disc screw 14. The connecting disc sealing plate 13 is locked onto the main drive shaft 16 by the main drive shaft locking nut A11 and the main drive shaft locking nut B12. The main shaft driven gear 19 is connected to the main drive shaft 16 by the main shaft driven gear connecting screw 18.

[0045] In the initial stage of startup, the driven gear 19 of the main shaft meshes with the drive gear 38 of the upper rotor, transmitting power to the main drive shaft 16, thereby transmitting power in reverse to the upper rotor.

[0046] like Figure 2 , Figure 3 As shown, the lower rotor drive shaft system 2 includes: a lower rotor connecting flange 21, a lower rotor drive flange 22, a lower rotor locking nut 23, a lower rotor brush seal 24, a lower rotor drive shaft 25, and a lower rotor driven gear 26.

[0047] The driven gear 26 of the lower rotor and the connecting flange 21 of the lower rotor are welded to the drive shaft 25 of the lower rotor. The drive flange 22 of the lower rotor is fixed to the connecting flange 21 of the lower rotor by screws. At the same time, the lower rotor is fixed to the connecting flange 21 of the lower rotor by screws. The brush seal 24 of the lower rotor is fixed to the drive shaft 25 of the lower rotor by the locking nut 23 of the lower rotor.

[0048] In the initial stage of startup, the power on the drive shaft 36 is output in the same direction through two meshings between the lower rotor drive gear 32 and the drive shaft idler gear 31 and the lower rotor driven gear 26. The power is then transmitted to the lower rotor through the lower rotor transmission shaft 25. The transmission ratio of the main transmission shaft system and the lower rotor transmission shaft system is the same, and the power input source is on the drive shaft. Thus, the coaxial dual rotors rotate in opposite directions at the same speed.

[0049] like Figures 1-3 As shown, the follower shaft system 4 includes: a follower shaft idler wheel 41, a lower rotor follower gear 42, a lower rotor follower gear mounting bolt 43, a lower rotor follower gear washer 44, a follower shaft bushing 45, a follower shaft 46, an upper rotor follower gear spacer 47, an upper rotor follower gear 48, an upper rotor follower gear washer 49, a flange nut 410, an upper rotor follower gear deep groove ball bearing 411, and a lower rotor follower gear deep groove ball bearing 412.

[0050] The upper rotor follower gear 48, the upper rotor follower gear deep groove ball bearing 411, the lower rotor follower gear deep groove ball bearing 412, and the lower rotor follower gear 42 are coaxially sleeved on the follower shaft 46. The upper rotor follower gear 48 and the lower rotor follower gear 42 are connected to the follower shaft 46 by a key. The lower rotor follower gear 42 is coaxially fitted with the lower rotor follower gear washer 44 on the follower shaft 46 and then connected to the follower shaft 46 by the lower rotor follower gear mounting bolt 43. The follower shaft sleeve 45 is fitted on the follower shaft 46 after cooperating with the upper rotor follower gear deep groove ball bearing 411 and the lower rotor drive gear deep groove ball bearing 412, realizing the protection function of the sleeve. The upper rotor follower gear spacer 47 is fitted on the follower shaft 46 and located above the upper rotor follower gear 48. The follower shaft 46 is fixed to the gearbox by a flange nut 410.

[0051] In the initial startup phase, the upper rotor follower gear 48 meshes with the main shaft driven gear 19, transmitting power in the reverse direction to the follower shaft 46. The lower rotor follower gear 42, through two meshes with the follower shaft idler gear 41 and the lower rotor driven gear 26, transmits power in the same direction to the follower shaft 46. At this point, the power transmissions in the same direction converge on the follower shaft. The coordinated use of the follower shaft system and the drive shaft system efficiently transmits power, improves the continuity and stability of the transmission, and simultaneously increases transmission efficiency, balancing the speed difference between the upper and lower rotors.

[0052] like Figure 4 , Figure 5As shown, the hot gas transmission assembly 6 and the cold gas transmission assembly 7 respectively include: a central hot gas outer pipe 61, a central hot gas inner pipe 62, an inner pipe upper base 63, an inner pipe lower base 64, and an outer cold gas outer pipe 71.

[0053] Both the central hot air outer pipe 61 and the central hot air inner pipe 62 are welded to the inner pipe upper base 63, and both the inner pipe upper base 63 and the outer cold air outer pipe 71 are welded to the inner pipe lower base 64. Figure 4 As shown, Hot air inlets and cold air inlets are respectively opened on the central hot air outer pipe 61 and the outer cold air outer pipe 71. Hot air flows in the channel between the central hot air outer pipe 61 and the central hot air inner pipe 62, while cold air flows in the channel between the central hot air outer pipe 61 and the outer cold air outer pipe 71. Cold air also flows in the main drive shaft 16. The main drive shaft sealing assembly A17 and the main drive shaft sealing assembly B110 are fastened with screws, and the lower rotor brush seal 24 is fixed to the lower rotor drive shaft 25 with screws. The sealing device prevents the mixing and outflow of hot and cold air. In order to achieve tip jet propulsion, the above-mentioned flow channels need to be reserved in the transmission system. Considering the requirements of the rotor speed at the initial start-up and the relationship between the speed of the piston engine, a transmission ratio of 4 is determined to be more suitable. Therefore, the number of teeth of the main shaft driven gear 19 and the lower rotor driven gear 26 can be designed to be larger, and their gear disk radius should be larger, and the number of teeth should be that of idler gears. Based on the principle that the ratio of transmission ratio to speed ratio is inversely proportional to the number of teeth, when a piston engine is used as the power source during the initial startup phase, this planetary gear structure can reduce the speed at which the piston engine outputs power, thus achieving the function of speed reduction and torque increase.

[0054] After startup, the rotor reaches a certain speed. At this time, the power of the piston engine is disengaged by the overrunning clutch 5, and the gas turbine is used as the power source. The hot air flows through the channel between the central hot air outer pipe 61 and the central hot air inner pipe 62 to the upper and lower rotors, and then flows through the channel between the upper and lower rotors to the blade tip. The hot air is ejected from the blade tip as a reverse thrust to drive the rotor to rotate. The power of the upper rotor is transmitted to the driven gear 19 of the main shaft via the upper rotor connecting plate 15 and the main drive shaft 16. The driven gear 19 meshes with the upper rotor drive gear 38 and the upper rotor follower gear 48, respectively, transmitting the power in the opposite direction to the drive shaft 36 and the follower shaft 46. The power of the lower rotor is transmitted to the lower rotor drive shaft 25 via the lower rotor connecting flange 21 and the lower rotor transmission flange 22. The lower rotor drive shaft 25 then transmits the power to the lower rotor driven gear 26. The lower rotor driven gear 26 meshes with the drive shaft idler gear 31 and the follower shaft idler gear 41, respectively. Then, the two idler gears mesh again with the lower rotor drive gear 32 and the lower rotor follower gear 42, respectively, transmitting the power in the same direction to the drive shaft 36 and the follower shaft 46. Since the upper and lower rotors generate opposite power sources, their power converges in the same direction on the drive shaft 36 and the follower shaft 46. At this point, the power generated by the upper and lower rotors converges on the drive shaft 36 and the follower shaft 46. If there is a phase difference between the upper and lower rotors, the drive shaft 36 and the follower shaft 46 can ensure that the phase difference between the upper and lower rotors is consistent, while balancing the uneven thrust caused by the difference in jet volume between the upper and lower rotors. Therefore, the speed difference between the upper and lower rotors is also balanced, ensuring that the coaxial dual rotors achieve constant speed and counter-rotation.

[0055] The above device realizes the transmission mechanism for propeller tip jet, simplifies the transmission mechanism, reduces the weight of the transmission mechanism, improves its power-to-weight ratio, realizes the upper and lower rotors to rotate in opposite directions at the same speed, balances the speed difference between the upper and lower rotors, and improves transmission efficiency.

[0056] The present invention also discloses a coaxial twin-rotor tip jet aircraft piston engine-gas turbine composite power system with the aforementioned transmission system. The composite power system includes a piston engine, a gas turbine, and a control system. The piston engine provides rotational power to the upper rotor and the lower rotor. The hot gas provided by the gas turbine is ejected from the tip of the rotor through the hot gas delivery assembly 6, providing rotational power to the rotor. The gas turbine also provides high-pressure gas to the piston engine.

[0057] The control method for the piston engine-gas turbine hybrid power system includes: First, the system's sensors collect operating condition signals, including rotor speed, gas turbine output power, and piston engine output power. Subsequently, upon receiving the start command, the gas turbine starts, and the gas output from the gas turbine drives the piston engine, which in turn drives the rotor to accelerate its rotation. When the rotor speed exceeds the idle speed threshold, the target power is obtained based on the total required power and the output power of the piston engine. The steps for obtaining the target power specifically include: A dual-modal cooperative driving dynamic model is established, with the following expression: (1) in, This represents the rotor's moment of inertia. Indicates the rotor speed. and They represent Rotation speed at all times The corresponding piston engine and gas turbine output torque, , These represent transmission efficiency, respectively. , Indicates the clutch transmission coefficient. Indicates rotational speed The corresponding rotor aerodynamic load torque.

[0058] The piston engine output torque is calculated based on the dual-modal cooperative drive dynamics model, and the piston engine output power is determined from the piston engine output torque; the target power is obtained by subtracting the piston engine output power from the total required power.

[0059] The gas turbine provides power to the upper and lower rotors based on the target power, so that both the piston engine and the gas turbine drive the upper and lower rotors to rotate.

[0060] Subsequently, the piston engine maintains maximum output power, and the rotor aerodynamic load torque estimate is obtained in real time based on the extended Kalman filter. The output power of the gas turbine is then adjusted based on the rotor aerodynamic load torque estimate. The estimated value of rotor aerodynamic load torque is obtained in real time based on extended Kalman filtering, and the expression is: (2) in, This represents the estimated value of the rotor aerodynamic load torque. Indicates air density, Indicates the torque coefficient. R Indicates the rotor radius; The rotor aerodynamic torque estimate is input into the dual-mode cooperative drive dynamics model to adjust the gas turbine output power in real time.

[0061] Finally, the system energy change is determined based on the output power of the gas turbine; it is then determined whether the subsequent operating mode is cruise or maneuvering flight; and different processing is performed depending on whether it is cruise or maneuvering flight.

[0062] During cruise operation, the system switches to a functionally decoupled mode to achieve optimal global energy efficiency. The piston engine gradually reduces its power output, and then the clutch automatically disconnects the power connection between the piston engine and the rotor. The piston engine power is redirected to the power generation system, completing the mode transition. The piston engine enters a high-efficiency power generation mode, operating at the globally optimal fuel consumption point to supply power to the onboard systems.

[0063] During this process, the torque output of each part is dynamically adjusted, and multi-objective optimization is performed based on the output power of the gas turbine and the output power of the piston engine to obtain the optimized output power of the gas turbine. The expression for multi-objective optimization is: (3) Where min represents minimization optimization. For the rotor reference angular velocity, This represents the change in generator torque of the piston engine. These are the weighting coefficients. , These represent the output power of the gas turbine and the piston engine, respectively. For cruise operation, this invention adjusts... The weighting coefficient is reduced. The weighting coefficient is increased. The weighting coefficients are adjusted to adapt to cruise conditions. In some embodiments, this can be achieved by... The weighting coefficient was adjusted from 0.6 to 0.2, making The weighting coefficient was adjusted from 0.1 to 0.7.

[0064] After the above multi-objective optimization process, the optimized gas turbine output power is obtained.

[0065] The gas turbine is controlled by the optimized gas turbine output power, so that the gas turbine focuses on maintaining lift. Its power command is also corrected by the minimum energy consumption multi-objective optimization algorithm. Under the premise of meeting the lift requirements, it is made to operate in its own high-efficiency range, and the overall system achieves the optimal cruise energy efficiency.

[0066] For maneuvering flight conditions, the piston engine is controlled to resume driving the upper and lower rotors, specifically by controlling the clutch between the piston engine and the upper and lower rotors to engage based on the energy changes of the system.

[0067] The foregoing has only described preferred embodiments of the present invention in detail and is not intended to limit the invention. Those skilled in the art will readily conceive of other embodiments of this disclosure upon considering the disclosure in the specification and embodiments. This application is intended to cover any variations, uses, or adaptations of this disclosure that follow the general principles of this disclosure and include common knowledge or customary techniques in the art not disclosed herein. The specification and embodiments are to be considered exemplary only, and the true scope and spirit of this disclosure are indicated by the claims.

Claims

1. A transmission system for a coaxial dual-rotor propeller jet aircraft, characterized in that, The transmission system is applied to a coaxial dual-rotor aircraft, which includes a coaxial upper rotor and a lower rotor. In the initial stage of startup, the engine drives the rotor to rotate. After reaching a certain speed, the engine disconnects the power and then uses gas as the power source. The rotor is driven to rotate by the counter-torque formed by the high-pressure and high-speed airflow ejected from the rotor tip, and the rotor is provided with lift. The transmission system includes a main drive shaft system, a lower rotor drive shaft system, a drive shaft system, a follower shaft system, an overrunning clutch assembly, a hot air supply assembly, and a cold air supply assembly. The overrunning clutch assembly connects to the engine and transmits the engine's power to the drive shaft system during the initial startup phase. The drive shaft system then transmits the power to the main drive shaft system and the lower rotor drive shaft system. The main drive shaft system drives the upper rotor, and the lower rotor drive shaft system drives the lower rotor, causing the upper and lower rotors to rotate in opposite directions at the same speed. Once the upper and lower rotors reach a certain speed, the overrunning clutch assembly automatically disengages and cuts off the engine's power input. When the upper and lower rotors drop below a certain speed, the engine disconnects its power, and the overrunning clutch assembly automatically engages the engine's power input and transmits power to the drive shaft system. When there is a phase difference between the upper and lower rotors, the phase difference between the upper and lower rotors is kept consistent through the drive shaft and the follower shaft.

2. A transmission system for a coaxial dual-rotor jet aircraft according to claim 1, wherein, The overrunning clutch assembly (5) includes an overrunning clutch connecting flange (51), an overrunning clutch housing (53), a star wheel (57), an adjustment shaft (58), rollers (59), and a spring pin assembly (510). The star wheel (57) is connected to the adjustment shaft (58) by a flat key. The overrunning clutch housing (53) is fitted on the star wheel (57) with a partial gap. The star wheel (57) has a wedge slot. A transverse gap is left on one side of the wedge slot to place the spring pin assembly (510), and a roller (59) is placed on the other side. In the initial stage of startup, a piston engine is used as the power source input. The power of the piston engine is first received by the adjustment shaft (58). The adjustment shaft (58) drives the star wheel (57) to rotate at a constant speed. Under the action of friction, the roller (59) is wedged between the overrunning clutch housing (53) and the star wheel (57), thereby transmitting the power to the overrunning clutch connecting flange (51). When the rotational speed of the overrunning clutch connecting flange (51) is greater than the rotational speed of the adjustment shaft (58), the roller (59) is released from the wedged gap and it disengages from the overrunning clutch housing (53). The power of the adjustment shaft is no longer transmitted to the overrunning clutch connecting flange (51).

3. A transmission system for a coaxial dual-rotor jet aircraft according to claim 2, wherein, The drive shaft system includes a drive shaft idler wheel (31), a lower rotor drive gear (32), a drive shaft (36), and an upper rotor drive gear (38). The upper rotor drive gear (38) and the lower rotor drive gear (32) are connected to the drive shaft (36) by a key. The drive shaft (36) is connected to the overrunning clutch connecting flange (51) by a flat key and screws. The drive shaft idler (31) meshes with the lower rotor drive gear (32) once. In the initial stage of startup, the overrunning clutch connecting flange (51) drives the drive shaft (36) to rotate at a constant speed, thereby transmitting power to the upper rotor drive gear (38) and the lower rotor drive gear (32). The lower rotor drive gear (32) then achieves the drive shaft idler gear (31) to rotate in the opposite direction at a constant speed through a single meshing with the drive shaft idler gear (31).

4. A transmission system for a coaxial dual-rotor jet aircraft according to claim 3, wherein, The main drive shaft system includes: a main drive shaft (16) and a main shaft driven gear (19), the main shaft driven gear (19) being connected to the main drive shaft (16); In the initial stage of startup, the driven gear (19) of the main shaft meshes with the drive gear (38) of the upper rotor, transmitting power to the main drive shaft (16), thereby transmitting power in reverse to the upper rotor.

5. A transmission system for a coaxial dual-rotor jet aircraft according to claim 3, wherein, The lower rotor drive shaft system (2) includes a lower rotor drive shaft (25) and a lower rotor driven gear (26). The driven gear (26) of the lower rotor is welded to the drive shaft (25) of the lower rotor; In the initial stage of startup, the power on the drive shaft (36) is output in the same direction through two meshings between the lower rotor drive gear (32), the drive shaft idler gear (31), and the lower rotor driven gear (26), and then transmitted to the lower rotor through the lower rotor transmission shaft (25).

6. A transmission system for a coaxial dual-rotor jet aircraft according to claim 4, wherein, The follower shaft system includes a follower shaft idler wheel (41), a lower rotor follower gear (42), a follower shaft (46), and an upper rotor follower gear (48). The upper rotor follower gear (48) and the lower rotor follower gear (42) are connected to the follower shaft (46) by a key; In the initial stage of startup, the upper rotor follower gear (48) meshes with the main shaft driven gear (19) to transmit power in the reverse direction to the follower shaft (46). The lower rotor follower gear (42) meshes with the follower shaft idler gear (41) and the lower rotor driven gear (26) twice to transmit power in the same direction to the follower shaft (46).

7. A transmission system for a coaxial dual-rotor jet aircraft according to claim 1, wherein, It also includes an inner tube upper base (63) and an inner tube lower base (64), the hot air transmission assembly (6) includes a central hot air outer tube (61) and a central hot air inner tube (62), and the cold air transmission assembly (7) includes an outer cold air outer tube (71). The central hot air outer pipe (61) and the central hot air inner pipe (62) are both welded to the inner pipe upper base (63), and the inner pipe upper base (63) and the outer cold air outer pipe (71) are both welded to the inner pipe lower base (64); Hot air inlet and cold air inlet are respectively opened on the central hot air outer pipe (61) and the outer cold air outer pipe (71). Hot air flows in the channel between the central hot air outer pipe (61) and the central hot air inner pipe (62), and cold air flows in the channel between the central hot air outer pipe (61) and the outer cold air outer pipe (71). Cold air also flows in the main drive shaft (16).

8. A transmission system for a coaxial dual-rotor jet aircraft according to claim 7, wherein, The hot air comes from the gas turbine and is ejected from the blade tip as a reverse thrust to drive the rotor to rotate. The cold air is used to cool the components in the transmission mechanism that need to be cooled.

9. A coaxial dual-rotor prop-fan aircraft piston engine-gas turbine compound power system with the transmission system of any one of claims 7-8, characterized in that, The composite power system includes a piston engine, a gas turbine, and a control system; the piston engine provides rotational power to the upper rotor and the lower rotor; the hot gas provided by the gas turbine passes through the hot gas delivery assembly (6) and is ejected from the blade tip to provide rotational power to the rotor; the gas turbine also provides high-pressure gas to the piston engine.

10. A control method for the piston engine-gas turbine combined power system of claim 9.

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