Light helicopter transmission system movably provided with low-speed piston engine

Abstract

The invention belongs to the field of helicopter transmission systems, and particularly relates to a light helicopter transmission system movably provided with a low-speed piston type engine. Comprising a main speed reducer (1), a belt transmission assembly (2), a tail transmission shaft assembly (3), a tail speed reducer (4), an engine (5), an upper belt wheel assembly (7), an electric tensioning actuating device (8), an engine rear installation anti-vibration pad assembly (9), a lower belt wheel (10), a combined V-shaped belt (11), a fan (12), a connecting bolt (13) and a step threaded bushing (15). The clutch device adapts to the layout of a movably-installed low-speed piston type engine, a large number of parts such as a sleeve tooth spline engine transmission shaft, a lower belt wheel shaft, a belt wheel support, a tensioning wheel, a support, a tensioning wire system and a load limiting mechanism can be omitted, and the starting clutch function of the aviation low-speed piston engine is reliably achieved.

Description

Technical Field

[0001] The invention belongs to the field of helicopter transmission systems, and particularly relates to a light helicopter transmission system for movably installing a low-speed piston engine. Background Art

[0002] The market requires unmanned and light helicopters to be inexpensive. Therefore, piston aviation engines are generally selected for unmanned and light helicopters. They have the advantages of low price, low fuel consumption rate, high reliability, and convenient maintenance support. However, they also have disadvantages such as large volume, heavy weight, and low power-to-weight ratio. Therefore, helicopter piston engines are generally arranged below the main reducer platform, and a belt drive assembly for parallel transmission is required to transmit power.

[0003] Helicopters generally use high-speed piston engines with an output speed of about 6000 rpm, and a centrifugal clutch is used to achieve the clutch function. However, in the general aviation market, there are few models of aviation high-speed piston engines, and the power coverage range is small, making it difficult to meet the requirements of helicopter research and development. Since there are a large number of general aviation fixed-wing propeller aircraft, the low-speed piston aviation engines selected for their propellers are inexpensive, developed and mature, highly reliable, and convenient for maintenance support. There are many models and a large power coverage range, which can better meet the power requirements for the research and development of unmanned and light helicopters. However, the output speed of aviation low-speed piston engines is low, generally about 2000 rpm. If such mature low-speed piston engines follow the technical route of centrifugal clutches for high-speed piston engines, the weight of the matched clutch is too large to be acceptable for the whole aircraft. Therefore, new technical routes must be adopted for low-speed piston aviation engines to achieve the clutch function of engine starting and shutdown.

[0004] With the development of helicopter technology, higher requirements are also placed on the transmission system, especially the belt drive assembly. It is required to isolate vibration and dampen shock and dissipate heat for the piston engine, and also to have high reliability, simple structure, flexible operation, light weight, convenient installation and adjustment, good ergonomics, be able to accurately adjust and control the belt tension, and eliminate the influence of belt wear in real time. Summary of the Invention

[0005] Object of the Invention: To provide a light helicopter transmission system for movably installing a low-speed piston engine, improving reliability and achieving simple and lightweight structure.

[0006] Technical Solution:

[0007] A light helicopter transmission system for movably installing a low-speed piston engine includes: a main reducer 1, a belt drive assembly 2, a tail drive shaft assembly 3, a tail reducer 4, an engine 5, an upper pulley assembly 7, an electric tensioning actuator 8, an engine rear mounting vibration damping pad assembly 9, a lower pulley 10, a joined V-belt 11, a fan 12, a connecting bolt 13, and a stepped threaded bushing 15. Among them,

[0008] The housing of the main reduction gear 1 is connected to the aircraft fuselage structure 6 by passing bolt assemblies through a special shock absorber; the upper pulley assembly 7 of the belt drive assembly 2 is sleeved on the first-stage external spline of the input gear shaft 16 of the main reduction gear 1 through its internal spline, and the flange of the electro-tensioning actuator 8 is sleeved on the second-stage external spline of the input gear shaft 16 of the main reduction gear 1 through its internal spline. A large nut 23 is used to lock and fasten the upper pulley assembly 7 and the electro-tensioning actuator 8 to the input gear shaft 16 of the main reduction gear 1; the electro-tensioning actuator 8 is bolted to the lug of the aircraft fuselage structure 6 through the spherical plain bearings 42 of its two adjustable-length tie rods 44 on the left and right sides.

[0009] The lower pulley 10 is fixedly connected to the output flange of the engine 5 through a connecting bolt 13; the output gear of the main reduction gear 1 is fixedly connected to the rotor shaft; one end of the tail drive shaft assembly 3 is connected to the external spline of the input shaft of the tail reduction gear 4 through its internal spline; the other end flange of the tail drive shaft assembly 3 is fixedly connected to the flange of the electro-tensioning actuator 8; the output shaft of the tail reduction gear 4 is connected to the tail rotor hub; the upper pulley assembly 7 and the lower pulley 10 are connected by a V-ribbed belt 11; the movable end of the electro-tensioning actuator 8 is connected to the front mounting bracket of the engine 5 through a spherical plain bearing; the engine rear mounting shock absorber assembly 9 is arranged between the rear mounting bracket of the engine 5 and the aircraft fuselage structure 6 as a rear hinge point; the fan 12 is arranged on the output flange of the engine 5 and is located in front of the lower pulley 10; a stepped threaded bushing 15 is arranged in the mounting hole of the output flange of the engine 5.

[0010] Further, the upper pulley assembly 7 includes: an upper pulley 51, an inner ring sleeve 52, a lip seal 53, an overrunning clutch freewheel 54, a clutch support bearing 55, a connecting bolt 56, a shaft with internal spline and external raceway 57, a rear seal 58, and a ball bearing 59, where

[0011] The inner hole and inner end face of the upper pulley 51 cooperate with the outer cylindrical surface and outer end face of the inner ring sleeve 52 to form concentric and axial positioning, and then they are connected and fixed into one body through 3 groups of connecting bolts 56; the overrunning clutch freewheel 54 and the clutch support bearing 55 are successively assembled between the inner hole of the inner ring sleeve 52 and the outer raceway surface of the shaft with internal spline and external raceway 57 to form the main structure of a wedge-type freewheel overrunning clutch; 3 ball bearings 59 and a rear seal 58 are installed in the smallest inner hole on the right side of the upper pulley 51; and together with the lip seal 53 and the rear seal 58, a lubricating oil storage space is formed.

[0012] Further, the hub of the upper pulley 51 is offset to the right, and the hub of the lower pulley 10 is offset to the left.

[0013] Further, the central hole of the lower pulley 10 is fitted with the boss of the fan 12 and the boss of the output flange 14 of the engine 5 to achieve concentric positioning; a set of six stepped threaded bushings 15 are press-fitted into the bolt holes of the output flange 14 from the back with interference. The connecting bolt 13 passes through the bolt holes of the fan 12 and the lower pulley 10 and is screwed into the internal thread of the stepped threaded bushing 15 on the output flange 14 for threaded connection, thus connecting the lower pulley 10, the fan 12 and the output flange of the engine 5 together.

[0014] Further, the V-shaped teeth of the multi-V-belt 11 are sleeved in the corresponding V-shaped grooves of the upper pulley 51 and the lower pulley 10 inside the belt drive assembly 2. In the working state, the engine 5 drives the lower pulley 10 to rotate, the lower pulley 10 then drives the multi-V-belt 11 to move, and finally the multi-V-belt 11 drives the upper pulley 51 to rotate to transmit power. The multi-V-belt 11 reduces the probability of abnormal conditions such as slipping, eccentric wear, and uneven wear occurring during the clutch process of multiple individual V-belts.

[0015] Further, the electro-tensioning actuator 8 of the belt drive assembly 2 is connected to the double-ear piece of the front mounting bracket of the engine 5 by a bolt assembly through the spherical plain bearing 26 at its lower end to form a front hinge point for engine mounting; the engine casing is connected to its own front mounting bracket and rear mounting bracket by bolts, and the rear mounting bracket of the engine 5 and the helicopter fuselage 6 are connected by two sets of vibration damping pad assemblies 6 with bolt assemblies to form a rear hinge point for engine mounting. The elongation or shortening of the electro-tensioning actuator 8 can pull the engine 5 to deflect at a small angle around the rear hinge point for engine mounting, thereby realizing the power transmission and clutch functions of the engine 5.

[0016] Further, the electro-tensioning actuator 8 includes: an upper rubber vibration damping pad 20, an upper bearing rubber ring 21, an internal spline output flange 22, a large nut 23, an upper spherical bearing 24, an anti-twist plate assembly 25, a lower spherical plain bearing 26, front and rear clamping plates 30, a DC motor 31, a planetary reducer 32, a lower housing 34, a worm and worm gear mechanism 35, a lead screw 36, a lead screw nut outer sleeve 37, an outer sleeve nut 38, a steel wire rope 39, a positioning bolt 40, a contraction limit position switch 41, an upper spherical plain bearing 42, a locking nut 43, an adjustable length pull rod assembly 44, a lower spherical plain bearing 45, an upper housing 46, a pressure sensor 47, and a tension limit position switch 48. Among them,

[0017] The DC motor 31 is installed on the planetary reducer 32, and the planetary reducer 32 is installed on the lower housing 34 of the electric tension actuator 8. After the rotation output by the DC motor 31 is amplified by the planetary reducer 32, the output shaft of the planetary reducer 32 drives the worm of the worm and worm gear assembly 35; the worm gear of the worm and worm gear assembly 35 is connected to the lead screw 36, and the lead screw 36 is screwed with the outer sleeve nut 38 at the lower end of the upper housing 46 to form a lead screw and nut assembly. The tops of the lead screw nut outer sleeve 37 and the outer sleeve nut 38 are connected by the anti-twist piece assembly 25, which does not allow relative rotation and can produce axial displacement; the worm gear of the worm and worm gear assembly 35 drives the lead screw 36 to rotate, and the lead screw 36 rotates in the threaded hole of the non-rotating outer sleeve nut 38, so as to drive the outer sleeve nut 38 to extend or retract relative to the lower housing 34.

[0018] The pressure sensor 47 is installed between the upper end of the lead screw 36 and the upper housing 46 to measure and monitor the tension of the electric tension actuator 8, so that the tension of the V-belt 11 can be estimated.

[0019] The tension limit position switch 48 is installed on the upper housing 46. The upper end of the steel wire rope 39 is connected to the tension limit position switch 48, and the lower end of the steel wire rope 39 passes through the through hole on the boss of the lower housing 34 and is installed with a limit block.

[0020] The contraction limit position switch 41 is installed on the upper housing 46, and the limit bolt 40 located below the contraction limit position switch 41 is installed on the boss of the lower housing 34 of the electric clutch device.

[0021] The outer ring of the upper end ball bearing 24 of the electric tension actuator 8 is installed with the upper end bearing rubber ring 21 and fixed on the upper housing 46. The internal spline flange 22 is fixedly connected to the inner ring of the support bearing 24. The internal spline flange 22 is sleeved and matched with the second-stage external spline of the input gear shaft 16 of the main reducer 1 through the internal spline, and the internal spline flange 22 and the input gear shaft 16 of the main reducer 1 are locked with a large nut 23 to form an integral body with the main reducer; the internal spline flange 22 is connected to the flange of the tail drive shaft assembly 3 through a laminated coupling with 3 sets of bolt assemblies; the power drives the internal spline flange 22, the laminated coupling of the internal spline flange 22, and the laminated coupling to drive the tail drive shaft assembly 3 to rotate from the input gear shaft 16 of the main reducer 1; the tail drive shaft assembly 3 drives the tail reducer 4 to rotate through a sliding spline pair.

[0022] The front and rear clamping plates 30 of the electro-tensioning actuator 8 are connected to the upper housing 46 through two groups of bolt assemblies, each passing through a set of left and right upper rubber vibration damping pads 20. The upper rubber vibration damping pads 20 can effectively isolate and reduce the engine vibration transmitted to the fuselage structure 10 through the left and right adjustable tie rods 44. One end of the two adjustable-length tie rods 44 is hinged to both sides of the front and rear clamping plates 30 through lower spherical bearings 45, and the other end is bolted to the lugs of the fuselage structure 6 through upper spherical bearings 42. The two sides of the adjustable-length tie rod 44 are respectively provided with positive and reverse threads. Therefore, by directly rotating the tube body of the adjustable-length tie rod 44 forward and backward, the length between the centers of the upper and lower spherical bearings can be adjusted, and then the locknut 43 is tightened and locked and a fuse is installed.

[0023] Furthermore, when the engine 5 starts, the electro-tensioning actuator 8 is in a contracted state, the distance between the two pulleys is short, and the belt is in a slack state and cannot transmit power. When the engine 5 is operating normally, the electro-tensioning actuator 8 is in a tensioned state, the distance between the two pulleys is long, and the V-belt 11 is in a tensioned state to achieve the power transmission function.

[0024] Beneficial effects:

[0025] Based on the concept and layout of cross-system integrated design, the present invention simplifies the structure, converts motion into static, and innovatively integrates the engine installation and force feedback control into the belt tensioning mechanism, adapting to the layout of the movable-mounted low-speed piston engine, which can eliminate a large number of components such as the splined engine transmission shaft, lower pulley shaft, pulley bracket, tensioner and its bracket, tension wire system and load-limiting mechanism, etc., and reliably realizes the starting and clutch function of the aviation low-speed piston engine; the addition of force feedback control and belt frequency detector can accurately calibrate and control the belt tension in real time; and a fan can be installed to realize the ventilation and heat dissipation of the engine and the main reduction gear. With appropriate load transmission and vibration damping design, it can effectively isolate and reduce the engine vibration, and cooperate with the vibration isolation and damping design of the main reduction gear to make the whole machine have a low vibration level. After flight test, the measured vibration of the whole machine is less than 0.1g.

[0026] The transmission system with a belt mechanism of this new configuration has a simple structure, light weight, high reliability of clutch function, precise control of belt tension load and strong anti-interference ability, compensates for the influence of belt wear on belt tension, adapts to the strong vibration working environment of the helicopter, and can also ensure the layout, ventilation and heat dissipation, vibration isolation and damping of the whole machine, make the belt work in an optimal state, extend the belt life, reduce the requirements for processing, installation and adjustment, is flexible in operation, has good ergonomics and is convenient for maintenance. Description of the drawings

[0027] Figure 1 is a schematic diagram of a transmission system of a light helicopter with a movable-mounted low-speed piston aviation engine;

[0028] Figure 2It is a structural diagram of a light helicopter transmission system for an actively installed low-speed piston aviation engine;

[0029] Figure 3 It is a structural diagram of the electro-tension actuator device of the light helicopter transmission system;

[0030] Among them, main reduction gear 1, belt drive assembly 2, tail drive shaft assembly 3, tail reduction gear 4, engine 5, aircraft fuselage structure 6, upper pulley assembly 7, electro-tension actuator 8, engine rear mounting shock absorber assembly 9, lower pulley 10, V-belt 11, fan 12, connecting bolt 13, output flange 14, stepped threaded bushing 15, input gear shaft 16, upper rubber shock absorber 20, upper bearing rubber ring 21, internal spline output flange 22, large nut 23, upper ball bearing 24, anti-torsion plate assembly 25, lower spherical plain bearing 26, front and rear clamping plates 30, DC motor 31, planetary reducer 32, lower housing 34, worm and worm gear mechanism 35, lead screw 36, lead screw nut outer sleeve 37, outer sleeve nut 38, wire rope 39, positioning bolt 40, shrink limit position switch 41, spherical plain bearing 42, locknut 43, adjustable length tie rod assembly 44, spherical plain bearing 45, upper housing 46, pressure sensor 47, tension limit position switch 48, upper pulley 51, inner ring sleeve 52, lip seal 53, overrunning clutch freewheel 54, clutch support bearing 55, connecting bolt 56, shaft with internal spline and outer raceway 57, rear seal 58, ball bearing 59. Specific implementation manners

[0031] To make the purpose, technical solutions and advantages of the implementation of this application clearer, the technical solutions in the implementation manners of this application will be described in more detail below with reference to the accompanying drawings in the implementation manners of this application. In the drawings, the same or similar reference numerals denote the same or similar elements or elements with the same or similar functions from beginning to end. The described implementation manners are part of the implementation manners of this application, rather than all of the implementation manners. The implementation manners described below by referring to the drawings are exemplary and are intended to explain this application, and should not be construed as a limitation of this application. Based on the implementation manners in this application, all other implementation manners obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of this application. The implementation manners of this application will be described in detail below with reference to the drawings.

[0032] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "axial direction", "vertical", "upper", "lower", "upper end", "bottom end", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation on the protection scope of the present invention.

[0033] A light helicopter transmission system for an actively installed low-speed piston engine of the present invention can not only adapt to the layout of a low-speed and high-torque piston aviation engine in a gyroplane, but also realize the clutch and vibration isolation installation for starting and shutting down the low-speed and high-torque piston aviation engine. An innovative implementation path for belt tensioning is proposed. At the same time, advanced control and sensor and other digital circuit technologies are adopted to realize a helicopter transmission system with real-time precise and constant control of belt tension.

[0034] Through in-depth research on the overall layout of the unmanned aerial vehicle, the vibration isolation installation and adjustment method of the engine, the precise adjustment control of the belt tension, and an innovative implementation path for belt tensioning, the present invention first proposes a new configuration scheme for a light helicopter transmission system with an actively installed low-speed piston aviation engine including a belt drive assembly in China. Based on the overall aircraft integrated layout and design concept, the structure is simplified, the movement is transformed into static, and the force control and engine installation are innovatively integrated into the belt tensioning mechanism. Compared with Figure 1 , Figure 2 the helicopter transmission system generally matching a low-speed piston aviation engine shown, the structure is simplified, saving a large number of parts such as pulley brackets, tension pulleys and brackets, etc.; the movement is transformed into static, changing the lower bearing connection component from the engine output shaft to the engine front bracket, and changing the rotational movement of the ball bearing during flight to the static support of the spherical plain bearing; the force control and engine installation are innovatively integrated into the structure of the belt tensioning mechanism. The electric tensioning actuator is added with a pressure sensor and a digital circuit of relevant force feedback control technology and a belt frequency detector. Its lower spherical plain bearing is connected to the engine front mounting bracket, and the rear mounting bracket is connected to the fuselage structure through a set of elastic vibration isolation pads, serving as the hinge point for its tensioning deflection movement, and cleverly using the engine outer casing as the deflection arm.

[0035] This scheme is mainly as described later, that is, the lower pulley is directly installed on the output flange of the piston engine, the joint bearing at the lower end of the electric tensioning actuator is connected to the ear of the front mounting bracket of the piston engine by bolts, and the rear mounting bracket of the piston engine is connected to the body structure by a group of rubber elastic vibration damping pads, which serves as the hinge fulcrum for the deflection of the belt tensioning movement; the upper pulley and the main reducer input gear shaft are assembled into one by an overrunning clutch shaft assembly; the output flange and the upper bearing and the bearing support are integrated with the pressure sensor and the electric tensioning actuator mechanism to form an electric tensioning actuator; the electric tensioning actuator is assembled with the outer spline of the main reducer input gear shaft through the internal spline of the output flange, and two small pull rods extend from both sides of the upper bearing seat of the electric tensioning actuator to connect with the fuselage structure, forming a fixed installation of the electric tensioning actuator, transmitting the generation The load on the front mounting point of the engine; by manipulating the length of the electric tensioning actuator, the joint bearing at the lower end of the electric tensioning actuator pulls the piston engine around the rubber elastic bearing at the rear mounting point as a deflection hinge fulcrum, and cleverly uses the engine outer casing as a deflection support arm, thereby driving the lower pulley on the engine output flange to deflect and move up and down, thereby realizing the distance adjustment between the upper and lower pulleys; the purpose of realizing the starting clutch function of the low-speed piston aircraft engine through belt tensioning and relaxation is achieved, avoiding the engine from starting with load, and realizing belt tensioning force calibration and real-time constant and precise control through digital circuit technologies such as pressure sensors and force feedback control and belt frequency detectors, while also ensuring that the belt works in the optimal state, extending the belt life, and reducing processing, installation and adjustment requirements. The entire light helicopter transmission system has a simple structure, eliminating a large number of parts such as the pulley bracket and tensioner and bracket, lower pulley shaft, bearing, bearing seat, spline engine output shaft, etc. It is light in weight, highly reliable, flexible in operation, good human-machine efficiency, easy to maintain, easy to install and adjust, good human-machine efficiency, can accurately adjust and control the belt tension, and eliminate the impact of belt wear in real time.

[0036] The composition, installation method and innovation of the transmission system are explained by taking a light helicopter transmission system configuration scheme with a movably mounted low-speed piston aircraft engine containing a belt drive assembly mechanism adapted to the rear-mounted engine layout as an example. Figures 1 - 3 The power transmission system of the light helicopter includes a main reducer 1, a belt drive assembly 2, a tail drive shaft assembly 3, a tail reducer 4 and an engine 5, wherein the belt drive assembly 2 is composed of an upper pulley assembly 7, an electric tension actuator 8, a lower pulley 10, a combined V-belt 11, an engine rear-mounted vibration damping pad assembly 9, a fan 12, a connecting bolt 13, a stepped threaded bushing 15, etc.

[0037] The main reduction gear 1 is connected to the aircraft fuselage structure 6 through 4 groups of bolt assemblies passing through a special shock absorber to form the installation reference of the transmission system; the upper pulley assembly 7 of the belt drive assembly 2 is sleeved on the first-stage external spline of the input gear shaft 16 of the main reduction gear 1 through its internal spline, and the electro-tensioning actuator 8 of the belt drive assembly 2 is sleeved on the second-stage external spline of the input gear shaft 16 of the main reduction gear 1 through its internal spline. A large nut 23 is used to lock and fasten the above two parts of the structure and the input gear shaft 16 of the main reduction gear 1 to form an integral body with the main reduction gear; the electro-tensioning actuator 8 of the belt drive assembly 2 is bolted to the lug of the aircraft fuselage structure 6 through the spherical plain bearings 42 of the two adjustable-length tie rods 44 on its left and right, transferring the belt load to the fuselage structure to prevent the main reduction gear 1 from bearing excessive load;

[0038] The upper pulley assembly 7 of the belt drive assembly 2 consists of an upper pulley 51, an inner ring sleeve 52, a lip seal 53, an overrunning clutch freewheel 54, a clutch support bearing 55, connecting bolts 56, an outer race shaft with internal splines 57, a rear seal 58, and a ball bearing 59, etc. The inner hole and inner end face of the upper pulley 51 cooperate with the outer cylindrical surface and outer end face of the inner ring sleeve 52 to form concentric and axial positioning, and then they are connected and fixed into an integral body through 3 groups of connecting bolts 56; the overrunning clutch freewheel 54 and the clutch support bearing 55 are successively assembled between the inner hole of the inner ring sleeve 52 and the outer raceway surface of the outer race shaft with internal splines 57 to form the main structure of the wedge-type freewheel overrunning clutch; 3 ball bearings 59 and a rear seal 58 are installed in the smallest inner hole on the right side of the upper pulley 51; together with the lip seal 53 and the rear seal 58, a lubricating oil storage space is formed; the above structural components together form the upper pulley assembly 7. The upper pulley assembly 7 adopts the design technology of offsetting the hub to the right for the upper pulley 51, so that the upper pulley 51 forms a large inner cavity with its larger inner diameter and the right offset of the hub; the end housing of the main reduction gear input shaft is wrapped in its inner cavity, effectively shortening the axial dimension of the entire mechanism and arranging the large-weight piston engine as close as possible to the center of gravity of the helicopter. The upper pulley 51 drives the inner ring sleeve 52, the inner ring sleeve 52 drives the overrunning clutch freewheel 54, the overrunning clutch freewheel 54 drives the outer race shaft with internal splines 57, and the outer race shaft with internal splines 57 drives the input gear shaft 16 of the main reduction gear 1 to rotate and transmit power; when the engine 5 fails or jams, the overrunning clutch freewheel 54 will not drive the inner ring sleeve 52 to rotate in the reverse direction, ensuring the autorotation and gliding of the helicopter.

[0039] The central hole of the lower pulley 10 of the belt drive assembly 2 is mated with the boss of the fan 12 and the boss of the output flange 14 of the engine 5 to achieve concentric positioning; a set of six stepped threaded bushings 15 are press-fitted into the bolt holes of the output flange 14 from the rear with interference. The connecting bolt 13 passes through the bolt holes of the fan 12 and the lower pulley 10 and is screwed into the internal thread of the stepped threaded bushing 15 on the output flange 14 for threaded connection, thus connecting the lower pulley 10, the fan 12 and the output flange of the engine 5 together; the lower pulley 10 of the belt drive assembly 2 adopts the hub offset design technology towards the left, so that the left offset of the hub of the lower pulley 10 forms a large inner cavity, which wraps the engine output flange and the output casing in its inner cavity, effectively shortening the axial dimension of the whole mechanism and arranging the large-weight piston engine as close as possible to the helicopter center of gravity.

[0040] The V-shaped teeth of the V-belt 11 are sleeved in the corresponding V-shaped grooves of the upper pulley 51 and the lower pulley 10 inside the belt drive assembly 2. In the working state, the engine 5 drives the lower pulley 10 to rotate, the lower pulley 10 then drives the V-belt 11 to move, and finally the V-belt 11 drives the upper pulley 51 to rotate to transmit power. The V-belt 11 can effectively reduce the probability of abnormal conditions such as slipping, eccentric wear, and uneven wear occurring in the clutch process of multiple individual V-belts.

[0041] The electro-tensioning actuator 8 of the belt drive assembly 2 is connected to the double-ear piece of the front mounting bracket of the engine 5 by a bolt assembly through the spherical plain bearing 26 at its lower end to form a front hinge point for engine mounting; the engine 5 casing is bolted to its front mounting bracket and rear mounting bracket, and the rear mounting bracket of the engine 5 and the helicopter fuselage 6 are connected by two sets of vibration damping pad assemblies 6 with bolt assemblies to form a rear hinge point for engine mounting. The elongation or shortening of the electro-tensioning actuator 8 can pull the engine 5 to deflect at a small angle around the rear hinge point for engine mounting, so as to realize functions such as power transmission and clutch of the engine 5.

[0042] The electro-tensioning actuator 8 is composed of an upper rubber vibration damping pad 20, an upper bearing rubber ring 21, an internal spline output flange 22, a large nut 23, an upper ball bearing 24, an anti-torsion sheet assembly 25, a lower spherical plain bearing 26, front and rear clamping plates 30, a DC motor 31, a planetary reducer 32, a lower housing 34, a worm and worm gear mechanism 35, a lead screw 36, a lead screw nut outer sleeve 37, an outer sleeve nut 38, a wire rope 39, a positioning bolt 40, a contraction limit position switch 41, a spherical plain bearing 42, a jam nut 43, an adjustable length pull rod assembly 44, a spherical plain bearing 45, an upper housing 46, a pressure sensor 47, a tension limit position switch 48, etc.

[0043] First, the DC motor 31 is installed on the planetary reducer 32, and the planetary reducer 32 is installed on the lower housing 34 of the electric tension actuator 8. After the rotation output by the DC motor 31 is amplified by the planetary reducer 32, the output shaft of the planetary reducer 32 drives the worm of the worm and worm gear assembly 35; the worm gear of the worm and worm gear assembly 35 is connected to the lead screw 36, and the lead screw 36 is screwed with the outer sleeve nut 38 at the lower end of the upper housing 46 to form a lead screw-nut assembly. The top ends of the lead screw nut outer sleeve 37 and the outer sleeve nut 38 are connected by the anti-twist piece assembly 25, which does not allow relative rotation and can generate axial displacement; the worm gear of the worm and worm gear assembly 35 drives the lead screw 36 to rotate, and the lead screw 36 rotates in the threaded hole of the non-rotating outer sleeve nut 38, thereby driving the outer sleeve nut 38 to extend or retract relative to the lower housing 34.

[0044] The pressure sensor 47 is installed between the upper end of the lead screw 36 and the upper housing 46 to measure and monitor the tension force of the electric tension actuator 8, so as to calculate the tension force of the V-belt 11.

[0045] The tension limit position switch 48 is installed on the upper housing 46. The upper end of the steel wire rope 39 is connected to the tension limit position switch 48, and the lower end of the steel wire rope 39 passes through the through hole on the boss of the lower housing 34 and is installed with a limit block.

[0046] The contraction limit position switch 41 is installed on the upper housing 46, and the limit bolt 40 located below the contraction limit position switch 41 is installed on the boss of the lower housing 34 of the electric clutch device.

[0047] The outer ring of the upper end ball bearing 24 of the electric tension actuator 8 is installed with the upper end bearing rubber ring 21 and fixed on the upper housing 46. The internal spline flange 22 is fixedly connected to the inner ring of the support bearing 24. The internal spline flange 22 is sleeved and matched with the second-stage external spline of the input gear shaft 16 of the main reducer 1 through the internal spline, and the internal spline flange 22 and the input gear shaft 16 of the main reducer 1 are locked with a large nut 23 to form an integral body with the main reducer; the internal spline flange 22 is connected to the flange of the tail drive shaft assembly 3 by 3 groups of bolt assemblies through the laminated coupling. Power is transmitted from the input gear shaft 16 of the main reducer 1 to drive the internal spline flange 22, the laminated coupling of the internal spline flange 22, and the laminated coupling to drive the tail drive shaft assembly 3 to rotate; the tail drive shaft assembly 3 drives the tail reducer 4 to rotate through the sliding spline pair.

[0048] The front and rear clamping plates 30 of the electro-tensioning actuator 8 are connected to the upper housing 46 through two groups of bolt assemblies, each passing through a set of left and right upper rubber vibration damping pads 20. The upper rubber vibration damping pads 20 can effectively isolate and reduce the engine vibration transmitted to the fuselage structure 10 through the left and right adjustable tie rods 44. One end of the two adjustable-length tie rods 44 is hinged to both sides of the front and rear clamping plates 30 through spherical plain bearings 45, and the other end is bolted to the lugs of the fuselage structure 6 through spherical plain bearings 42. The two sides of the adjustable-length tie rod 44 are respectively provided with positive and reverse threads. Therefore, by directly rotating the tube body of the adjustable-length tie rod 44 forward and backward, the length between the centers of the upper and lower spherical plain bearings can be adjusted, and then the locknut 43 is tightened and locked and the fuse is installed.

[0049] The lower spherical plain bearing 26, the upper and lower spherical plain bearings of the adjustable tie rod 44, the upper bearing rubber ring 21 and the upper rubber vibration damping pad 20 can compensate for the angular and displacement changes of the electric clutch device in the tensioning and retracting states.

[0050] The electro-tensioning actuator 8 can adjust the distance between the internal spline flange 22 and the lower spherical plain bearing 26 by extending or shortening, pulling the engine 5 to deflect at a small angle around the hinge point after the engine is installed, rotating around the Y axis of the helicopter, changing the distance between the upper pulley 51 and the lower pulley 10 in the belt drive assembly 2, and realizing the tensioning and loosening functions of the V-belt set 11, playing the role of power transmission and clutch, so as to realize the functions of power transmission and clutch of the engine 5.

[0051] When the engine 5 starts, the electro-tensioning actuator 8 is in the retracted state, the distance between the two pulleys is short, and the belt is in a slack state and cannot transmit power; when the engine 5 is working normally, the electro-tensioning actuator 8 is in the tensioned state, the distance between the two pulleys is long, and the V-belt set 11 is in the tensioned state to realize the power transmission function, as shown in Figure 1 shown.

[0052] When the engine 5 starts, the upper computer sends a tensioning signal to the control box of the electro-tensioning actuator 8. The DC motor 31 receives the tensioning motion control command and rotates. First, it is decelerated and torque-increased through the planetary reducer 32, and then decelerated and torque-increased again through the worm and worm gear assembly 35. The worm is integrated with the lead screw 36. The lead screw 36 is screwed with the outer sleeve nut 38 at the lower end of the upper housing 46 to form a lead screw-nut assembly. The upper housing 46 and the lower housing 34 are connected into an integral mechanism that can only move up and down through the anti-torsion plate assembly 25. Through the above structure, the rotational motion of the worm is converted into the linear motion of the outer sleeve nut 38.

[0053] Thereby, the distance between the internal spline flange 22 and the lower spherical plain bearing 26 is increased, and finally the output flange of the engine 5 is tilted downward along the Y axis, increasing the distance between the upper and lower pulleys, so that the V-belt set 11 is in the tensioned state ( Figure 1The solid line position) plays a role in transmitting power.

[0054] When the engine 5 stops, the control box of the electro-tensioning actuator 8 sends a contraction signal, and the DC motor 31 rotates in the reverse direction upon receiving the contraction movement control command. Eventually, it drives the output flange of the engine 5 to tilt upward along the Y axis, reducing the distance between the upper and lower pulleys, and making the V-ribbed belt 11 in a contracted state ( Figure 1 The dotted line position) plays a role in clutch.

[0055] During the tensioning process of the electro-tensioning actuator 8, the DC motor 31 rotates upon receiving the tensioning movement control command, driving the lower spherical plain bearing 26 to extend to the tensioning position. After triggering the pressure threshold of the pressure sensor 47, it reports to the control box, and the control box sends a signal to stop the movement, and locks the current position by the self-locking property of the worm gear and worm pair and the lead screw pair. When the pressure sensor 47 fails, the steel wire rope 39 triggers the tensioning limit position switch 48 to cut off the power supply of the system to protect the safety of the belt device.

[0056] In the process of calibrating and adjusting the belt tension of the V-ribbed belt 11, when the electro-tensioning actuator 8 is tensioned in place and triggers the pressure threshold of the pressure sensor 47, it reports to the control box. Use an Optibelt belt frequency measuring instrument to measure the belt frequency to ensure that the tensioning frequency of the V-ribbed belt 11 is within 67 Hz - 70 Hz (each tensioning frequency within the range of the V-ribbed belt 11 of a certain model corresponds to a corresponding belt tension). By adjusting the resistance of the pressure sensor control circuit of the electro-actuator control box, the tension of the V-ribbed belt 11 in the tensioned state can be adjusted and calibrated.

[0057] During the contraction process of the electric clutch device, the DC motor 31 rotates in the reverse direction upon receiving the contraction movement control command, driving the lower spherical plain bearing 26 to contract to the contraction position, causing the top of the positioning bolt 40 to trigger the contraction limit position switch 41 and stop the movement, and locks the current position by the self-locking property of the worm gear and worm pair and the lead screw pair.

[0058] The key points of the present invention:

[0059] Based on the concept and layout of cross-system integrated design, it simplifies the structure, turns motion into static state, and innovatively integrates force feedback control and engine installation into the belt tensioning mechanism. Compared with the helicopter transmission system generally matching low-speed piston aviation engines, it ingeniously directly sleeved and connected the lower pulley with the engine output flange. The electric tensioning actuator is sleeved on the main reduction input gear shaft through the internal spline of the output flange. Its upper part is directly connected to the fuselage structure through two adjustable tie rods with spherical bearings at both ends, forming its fixed installation with the helicopter; its lower spherical bearing is directly connected to the double lugs of the engine front mounting bracket, serving as the front movable hinge point for engine installation. The engine rear mounting bracket is connected to the fuselage structure through a group of rubber elastic vibration damping pads, serving as the rear mounting hinge point for the engine; when the electric tensioning actuator expands and contracts, it can pull the engine to deflect upward and downward along the Y axis around the rear mounting hinge point, driving the lower pulley on the engine output flange to move up and down, changing the distance between the upper and lower pulleys, and playing the role of clutch. It realizes the integration, combination and efficient utilization of the components for the clutch function of engine installation and belt drive assembly.

[0060] Based on the effect of simplifying the structure and turning motion into static state, it omits components such as the splined engine transmission shaft, lower pulley shaft, pulley bracket, tension pulley and its bracket, tension limiting mechanism, tension wire system, lower spherical bearing, etc. The upper spherical bearing is reduced from 2 to 1; the lower pulley bearing is changed from a spherical bearing to a spherical plain bearing, realizing the change from motion to static state.

[0061] Based on the overall idea of the whole aircraft ventilation and heat dissipation integration, the upper pulley and the lower pulley are opened with appropriate diagonal guide air holes according to the rotation direction, cooperating with the cooling fan connected to the lower pulley and the heat dissipation ventilation openings and channels of the fuselage to generate ventilation and cooling air flow, ensuring the ventilation and heat dissipation of the whole aircraft, especially the engine and the main reduction gear.

[0062] Based on the design of the upper bearing rubber ring and the upper rubber vibration damping pad of the electric clutch device to isolate and reduce the influence of engine vibration on the fuselage and the main reduction gear; the two adjustable tie rods and the aforementioned two rubber rings together with the main reduction gear and its rubber vibration damping pads isolate the belt load vibration and transmit it to the fuselage, and its laminated coupling ingeniously compensates for the deviation of the non-concentricity between the main reduction input shaft and the tail transmission shaft.

[0063] Based on the addition of a pressure sensor and a control box to the electric tensioning actuator, it converts displacement control into force feedback control; it can directly measure the pressure of the tensioning device screw rod, and can calculate the belt tension according to the position dimension relationship. The control box adopts digital circuit technology, has strong anti-interference ability, and adapts to the harsh working environment of strong vibration of the helicopter; it can accurately detect the voltage value of the pressure sensor to sense the slight change of the belt tension, and compensates in real time for the change of the belt tension caused by the wear of the belt and the pulley.

[0064] Furthermore, when calibrating the tension adjustment of the V-belt in the helicopter final assembly and belt disassembly and reinstallation, the electric actuator precisely measures the frequency of the belt in the tensioned state through a belt frequency measuring instrument. By selecting the corresponding relationship between each tension frequency and the belt tension value within the range of the V-belt, the magnitude of the belt tension force can be known. By adjusting the resistance of the pressure sensor control circuit in the control box, the belt tension force in the tensioned state can be regularly adjusted and calibrated. Compared with the belt tension control that combines the electric actuator, its displacement control method, and the load-limiting mechanism in the transmission system, it has the advantages of light system weight, high control accuracy, and real-time precise control force.

[0065] Through the combination of the above measures, the goal of using an aviation low-output speed and high-torque piston engine on a helicopter is achieved.

[0066] The above is only the specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the technical field within the technical scope disclosed in the present application should be covered by the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claimed rights.

Claims

1. A light helicopter transmission system for an actively installed low-speed piston engine, characterized in that, Comprising: Main reducer, belt drive assembly, tail drive shaft assembly, tail reducer, engine, upper pulley assembly, electro-tensioning actuator, engine rear mounting vibration damping pad assembly, lower pulley, link V-belt, fan, connecting bolts, stepped threaded bushings. The casing of the main reducer is connected to the aircraft fuselage structure; the upper pulley assembly of the belt drive assembly is sleeved on the first-stage external spline of the input gear shaft of the main reducer through its internal spline, and the flange of the electro-tensioning actuator is sleeved on the second-stage external spline of the input gear shaft of the main reducer through its internal spline. A large nut is used to lock the upper pulley assembly and the electro-tensioning actuator to the input gear shaft of the main reducer; the electro-tensioning actuator is connected to the lug of the aircraft fuselage structure through the spherical bearings of its two adjustable-length tie rods on the left and right; the lower pulley is fixedly connected to the output flange of the engine; the output gear of the main reducer is fixedly connected to the rotor shaft; one end of the tail drive shaft assembly is connected to the external spline of the input shaft of the tail reducer through its internal spline; The other end flange of the tail drive shaft assembly is fixedly connected to the flange of the electro-tensioning actuator; the output shaft of the tail reducer is connected to the tail rotor hub; the upper pulley assembly and the lower pulley are connected by a link V-belt; the movable end of the electro-tensioning actuator is connected to the front mounting bracket of the engine through a spherical bearing; The engine rear mounting vibration damping pad assembly is arranged between the rear mounting bracket of the engine and the aircraft fuselage structure as a rear hinge point; the fan is arranged on the output flange of the engine and is located in front of the lower pulley; stepped threaded bushings are arranged in the mounting holes of the output flange of the engine.

2. The light helicopter transmission system with a movable low-speed piston engine according to claim 1, characterized in that, The upper pulley assembly includes: upper pulley, inner ring sleeve, lip seal, overrunning clutch freewheel, clutch support bearing, connecting bolts, outer runway shaft with internal spline, rear seal and ball bearing, wherein, The inner hole and inner end face of the upper pulley cooperate with the outer cylindrical surface and outer end face of the inner ring sleeve to form concentric and axial positioning, and then are fixedly connected into one body through 3 groups of connecting bolts; the overrunning clutch freewheel and the clutch support bearing are successively assembled between the inner hole of the inner ring sleeve and the outer runway surface of the outer runway shaft with internal spline to form the main structure of the wedge-type freewheel overrunning clutch; 3 ball bearings and a rear seal are installed in the smallest inner hole on the right side of the upper pulley; together with the lip seal and the rear seal, a lubricating oil storage space is formed.

3. The light helicopter drive system for an activity-installed low-speed piston engine according to claim 2, characterized in that The hub of the upper pulley is offset to the right, and the hub of the lower pulley is offset to the left.

4. The light helicopter transmission system with a movable low-speed piston engine according to claim 1, characterized in that, The center hole of the lower pulley cooperates with the boss of the fan and the boss of the output flange of the engine to achieve concentric positioning; a set of 6 stepped threaded bushings are press-fitted into the bolt holes of the output flange from the rear with interference. The connecting bolts pass through the bolt holes of the fan and the lower pulley and are screwed into the internal threads of the stepped threaded bushings on the output flange for threaded connection, thus connecting the lower pulley, the fan and the output flange of the engine together.

5. The light helicopter transmission system with an active installation of a low-speed piston engine according to claim 2, characterized in that, The V-shaped teeth of the link V-belt are sleeved in the corresponding V-shaped grooves of the upper and lower pulleys in the belt drive assembly. In the working state, the engine drives the lower pulley to rotate, the lower pulley then drives the link V-belt to move, and finally the link V-belt drives the upper pulley to rotate to transmit power. The link V-belt reduces the probability of abnormal conditions such as slipping, eccentric wear, and uneven wear that occur in multiple individual V-belts during the clutch process.

6. The light helicopter transmission system for an activity-installed low-speed piston engine according to claim 1, characterized in that, The electro-tensioning actuator of the belt drive assembly is connected to the double-ear piece of the front mounting bracket of the engine by a bolt assembly through the spherical plain bearing at its lower end to form a front hinge point for engine mounting; the engine casing is connected to its own front mounting bracket and rear mounting bracket by bolts, and the rear mounting bracket of the engine and the helicopter fuselage are connected by two sets of vibration damping pad assemblies with bolt assemblies to form a rear hinge point for engine mounting. The elongation or shortening of the electro-tensioning actuator can pull the engine to deflect at a small angle around the rear hinge point of engine mounting, so as to realize the power transmission and clutch functions of the engine.

7. The light helicopter transmission system with a movable low-speed piston engine according to claim 1, characterized in that, The electro-tensioning actuator includes: upper rubber vibration damping pad, upper bearing rubber ring, internal spline output flange, large nut, upper spherical bearing, anti-torsion plate assembly, lower spherical plain bearing, front and rear clamping plates, DC motor, planetary reducer, lower housing, worm and worm gear mechanism, lead screw, lead screw nut outer sleeve, outer sleeve nut, steel wire rope, positioning bolt, contraction limit position switch, upper spherical plain bearing, locknut, adjustable length tie rod assembly, lower spherical plain bearing, upper housing, pressure sensor, tension limit position switch, where The DC motor is installed on the planetary reducer, and the planetary reducer is installed on the lower housing of the electro-tensioning actuator. After the rotational output of the DC motor is amplified by the planetary reducer, the output shaft of the planetary reducer drives the worm of the worm and worm gear assembly; the worm gear of the worm and worm gear assembly is connected to the lead screw, and the lead screw is screwed with the outer sleeve nut at the lower end of the upper housing to form a lead screw nut assembly. The top ends of the lead screw nut outer sleeve and the outer sleeve nut are connected by an anti-torsion plate assembly, and relative rotation is not allowed, and axial displacement can occur; the worm gear of the worm and worm gear assembly drives the lead screw to rotate, and the lead screw rotates in the threaded hole of the non-rotating outer sleeve nut, so as to drive the outer sleeve nut to extend or retract relative to the lower housing. The pressure sensor is installed between the upper end of the lead screw and the upper housing to measure and monitor the tension of the electro-tensioning actuator, so as to calculate the tension of the link V-belt. The tension limit position switch is installed on the upper housing, the upper end of the steel wire rope is connected to the tension limit position switch, and the lower end of the steel wire rope passes through the through hole on the boss of the lower housing and is installed with a limit block. The contraction limit position switch is installed on the upper housing, and the limit bolt located below the contraction limit position switch is installed on the boss of the lower housing of the electric clutch device. The upper ball bearing outer ring of the electro-tension actuator is installed with an upper bearing rubber ring and fixed on the upper housing. The internal spline flange is fixedly connected to the inner ring of the support bearing. The internal spline flange is sleeved and matched with the external spline of the second section of the input gear shaft of the main reducer through the internal spline. A large nut is used to lock and fasten the internal spline flange and the input gear shaft of the main reducer to form an integral body with the main reducer; the internal spline flange is connected to the flange of the tail drive shaft assembly through a laminated coupling with 3 sets of bolt assemblies; the power drives the internal spline flange, the laminated coupling of the internal spline flange, and the laminated coupling to drive the tail drive shaft assembly to rotate from the input gear shaft of the main reducer; the tail drive shaft assembly drives the tail reducer to rotate through a sliding spline pair; The front and rear clamping plates of the electro-tension actuator are respectively connected to the upper housing through 2 sets of bolt assemblies, each passing through a set of left and right upper rubber vibration damping pads. The upper rubber vibration damping pads can effectively isolate and reduce the engine vibration transmitted to the fuselage structure through the left and right adjustable tie rods; one end of the two adjustable-length tie rods is hinged to both sides of the front and rear clamping plates through a lower joint bearing, and the other end is bolted to the lug of the fuselage structure through an upper joint bearing; the two sides of the adjustable-length tie rod are respectively left- and right-handed threads. Therefore, by directly rotating the body of the adjustable-length tie rod forward and backward, the length adjustment between the centers of the upper and lower joint bearings can be achieved, and then a locking nut is used to lock and fasten it and a safety wire is installed.

8. The light helicopter transmission system with a movable low-speed piston engine according to claim 1, characterized in that, When the engine starts, the electro-tension actuator is in a contracted state, the distance between the two belt pulleys is short, and the belt is in a slack state and cannot transmit power; when the engine is working normally, the electro-tension actuator is in a tensioned state, the distance between the two belt pulleys is long, and the V-belt is in a tensioned state to achieve the power transmission function.

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