阅读说明：本技术 一种直升机尾减速器及直升机 (Helicopter tail speed reducer and helicopter ) 是由 于伟波 胡强 刘建斌 石前列 吴志广 刘志强 林琴锋 彭幕平 于 2020-07-16 设计创作，主要内容包括：本发明专利公开了一种直升机尾减速器及直升机,该直升机尾减速器包括机匣,以及设置在机匣内部的锥齿轮、助力器操纵杆、尾桨轴以及行星传动组件,其中：输入锥齿轮与输出锥齿轮为第一级减速,具备减速和换向功能。输出锥齿轮、行星传动组件与尾桨轴为第二级减速,具备减速和输出功率功能。该直升机还包括液压油缸、尾桨机构以及变距机构。本专利通过机匣,以及设置在所述机匣内部的输入锥齿轮、输出锥齿轮、以及与输出锥齿轮通过行星传动组件相连接的尾桨轴、以及桨距操纵轴和助力器操纵杆等结构,实现了尾减速器功能完整、结构紧凑,质量轻、强度高且具备较高的减速比的目的。(The invention discloses a helicopter tail speed reducer and a helicopter, wherein the helicopter tail speed reducer comprises a casing, and a bevel gear, a booster operating rod, a tail rotor shaft and a planetary transmission assembly which are arranged in the casing, wherein: the input bevel gear and the output bevel gear are in first-stage speed reduction and have speed reduction and reversing functions. The output bevel gear, the planetary transmission assembly and the tail rotor shaft are in second-stage speed reduction, and have the functions of speed reduction and power output. The helicopter also comprises a hydraulic oil cylinder, a tail rotor mechanism and a variable pitch mechanism. This patent passes through the machine casket, and sets up inside input bevel gear, the output bevel gear of machine casket and with the structure such as propeller shaft that output bevel gear is connected through planetary drive assembly and pitch control shaft and booster control rod, realized that tail reduction gear function is complete, compact structure, the light, the high and higher reduction ratio's of intensity purpose of quality.)

1. A helicopter tail reducer comprising:

a planetary drive assembly;

the device comprises a casing, a first connecting piece, a second connecting piece, a first connecting piece and a second connecting piece, wherein the casing is fixedly connected with a platform of a tail oblique beam body of the helicopter and comprises an input end and an output end;

the input bevel gear is used for being connected with a tail transmission shaft of the helicopter, is arranged in the case and is positioned at the input end;

the output bevel gear is arranged in the casing and meshed with the input bevel gear to form a first-stage speed change mechanism, the output bevel gear is of a hollow structure, and the center line of the output bevel gear is superposed with the center line of the output end and is a first center line;

the central line of the tail rotor shaft is coincident with the first central line and can be rotatably installed at the output end, the tail rotor shaft is in transmission connection with the output bevel gear through the planetary transmission assembly to form a two-stage speed change mechanism, the tail rotor shaft is of a hollow structure, and the surface of the tail rotor shaft is provided with a tail rotor installation interface for installing a tail rotor mechanism of a helicopter;

the central line of the propeller pitch control shaft is coincident with the first central line and is positioned on one side of the tail propeller shaft, which is far away from the output bevel gear, the propeller pitch control shaft is arranged in the tail propeller shaft, and the propeller pitch control shaft can axially slide and synchronously rotate relative to the tail propeller shaft;

booster control rod, booster control rod's central line with first central line coincides mutually, passes in proper order the propeller shaft with output bevel gear, booster control rod adopts the mode that two points of biserial self-aligning ball bearing and sliding sleeve supported, installs inside propeller pitch control shaft to adopt the locking of Suluke nut, booster control rod drives propeller pitch control shaft follows first central line slides.

2. A helicopter tail reducer according to claim 1,

the planetary transmission assembly comprises an inner gear ring, the center line of the inner gear ring is coincident with the first center line, a flange mounting edge is arranged on the outer wall of the inner gear ring, a plurality of first through holes are formed in the flange mounting edge, and the flange mounting edge can be fixedly connected with the casing through a threaded connecting piece;

and/or;

the thickness of the spoke plate of the inner gear ring is less than 2.5 times of the modulus.

3. A helicopter tail reducer according to claim 1,

the input bevel gear comprises an input bevel gear body, a first gear shaft and a second gear shaft, wherein the first gear shaft is positioned on the large end side of the input bevel gear body, the second gear shaft is positioned on the small end side of the input bevel gear body, a plurality of gear teeth are arranged on the input bevel gear body, the first gear shaft and the second gear shaft are rotatably fixed in the casing, and the first gear shaft can be connected with the tail transmission shaft through a flange plate;

the input bevel gear body, the first gear shaft and the second gear shaft are of an integrated structure, and the input bevel gear is mounted in a bearing hole of the casing in a simple support mode of a cylindrical roller bearing, a ball bearing and a roller bearing without an inner ring.

4. A helicopter tail reducer according to claim 1,

the output bevel gear comprises an output bevel gear body, a third gear shaft and a fourth gear shaft, wherein the third gear shaft is positioned on the large end side of the output bevel gear body, the fourth gear shaft is positioned on the small end side of the output bevel gear body, a plurality of gear teeth are arranged on the output bevel gear body, the third gear shaft and the fourth gear shaft are rotatably fixed in the casing, and a plurality of gear teeth are arranged on the surface of the third gear shaft;

the output bevel gear body, the third gear shaft and the fourth gear shaft are of an integrated structure.

5. A helicopter tail reducer according to claim 1,

the tail rotor shaft further comprises a tail rotor shaft main body and a tail rotor shaft flange, the tail rotor shaft flange and the tail rotor shaft main body are located on the same axis, the tail rotor mounting interface is arranged on the tail rotor shaft main body, and the tail rotor shaft flange is provided with a plurality of second through holes so as to assemble the planetary transmission assembly;

the tail rotor shaft flange and the tail rotor shaft main body are of an integrated structure;

the tail rotor shaft is arranged at the output end in a double-row roller bearing and inner ring-free roller bearing double-pivot supporting mode.

6. A helicopter tail reducer according to any of claims 2-5,

the planetary transmission assembly further includes a first bearing and a bearing sleeve;

the bearing sleeve is arranged in the second through hole, an inner ring of the first bearing is in interference fit with the bearing sleeve, a plurality of gear teeth are arranged on the surface of an outer ring of the first bearing, and the first bearing is matched with the inner gear ring and the third gear shaft; wherein the content of the first and second substances,

the third gear shaft is a sun gear of the planetary transmission assembly;

the first bearing is a planetary gear of the planetary transmission assembly;

the inner gear ring is an outer gear ring of the planetary transmission assembly;

the tail rotor shaft flange is a planet carrier of the planetary transmission assembly.

7. A helicopter tail reducer according to any of claims 2-5,

the engine casing comprises an input engine casing, a main engine casing and an output engine casing, wherein the main engine casing is internally in an L-shaped channel structure, the input engine casing and the output engine casing are respectively installed at two ports of the main engine casing, and the main engine casing is fixedly connected with the installation platform of the tail oblique beam body of the helicopter through a threaded connecting piece;

the input casing is of a disc structure, a bearing mounting hole and a lip-shaped oil seal mounting hole are formed in the center of the input casing, a plurality of mounting holes are formed in the periphery of the input casing, and the input casing can be fixedly connected with the casing main body through threaded connecting pieces;

the central line of the output casing coincides with the first central line, the output casing is of a conical hollow structure and is provided with a large end face and a small end face, the large end face extends outwards to form a flange structure, a plurality of mounting holes are formed in the flange, and the main casing, the flange mounting edge and the output casing are sequentially connected through threaded connecting pieces.

8. A helicopter tail reducer according to claim 1 further comprising:

the lubricating oil gear pump is fixed in the casing;

and the pump gear is fixed at one end of the input bevel gear and is in gear connection with the lubricating oil gear pump.

9. A helicopter tail reducer according to claim 3 or 8,

the first gear shaft is provided with a shaft shoulder, and one end of the shaft shoulder, which is far away from the input bevel gear body, is sequentially provided with the pump gear, a second bearing, a bearing adjusting pad, a third bearing and a flange plate, wherein the flange plate is axially fixed on the first gear shaft through a locking nut, a first clamping ring and a stop ring;

the flange plate abuts against the third bearing, and the pump gear abuts against the second bearing so as to clamp the casing and fix the input bevel gear;

and/or;

an input end lip-shaped oil seal is arranged between the flange plate and the casing, and the input end lip-shaped oil seal is fixed on one side of the third bearing through a second clamping ring.

10. A helicopter including a helicopter tail reducer as claimed in any one of claims 1 to 9 and further including:

the tail rotor is arranged on the tail rotor mounting interface, and the tail rotor mounting interface is positioned at an external spline of the tail rotor shaft;

the pitch control shaft is in transmission connection with the blades of the tail rotor through the pitch control mechanism;

the hydraulic oil cylinder is connected with the booster operating rod to drive the booster operating rod to slide along the first center line.

Technical Field

The invention relates to the technical field of helicopters, in particular to a tail speed reducer of a helicopter and the helicopter.

Background

The heavy helicopter plays a very important role in military transportation, and can carry a large amount of weaponry and soldiers to quickly arrive at a battlefield when a combat mission needs to be rapidly arrived at a designated combat area, so that the control of the dominant right of the battlefield is very critical; in addition, in the civil aspect, the heavy helicopter plays a role in lifting the heavy natural disasters in emergency rescue, and can complete tasks such as large equipment lifting, oil pipelines and power transmission lines erection, emergency air lifting, forest fire prevention, medical first aid, evacuation of refugees and the like. Such as rice-26, play an irreplaceable role in early Su Union Chenobel nuclear accidents, and in recent years Greek extra forest fire, Pakistan earthquake relief and Wenchuan earthquake rescue.

Based on the huge requirements of heavy helicopters on the aspects of military and civil, the development of the heavy helicopters is urgently needed in China, and the tail speed reducer is used as a core component of a transmission system, so that the research on the structure of the heavy helicopters is of great strategic significance. With the development of helicopter technology, the requirements for the tail speed reducer are higher and higher, and the tail speed reducer is required to be suitable for specific requirements and also to meet the characteristics of compact structure, strong bearing capacity, light weight, small overall dimension, high reliability, high reduction ratio, convenience in installation and adjustment and the like.

Therefore, whether can independently design a helicopter tail reduction gear, it is the problem that this patent wants to solve to accomplish that tail reduction gear function is complete, compact structure, the quality is light, intensity is high and possess higher reduction ratio.

Disclosure of Invention

Aiming at the defects in the prior art, the invention provides a helicopter tail reducer and a helicopter, so as to achieve the purposes of compact structure, light weight and higher reduction ratio of the tail reducer.

The technical scheme provided by the invention is as follows: a helicopter tail reducer comprising:

a planetary drive assembly; the device comprises a casing, a first connecting piece, a second connecting piece, a first connecting piece and a second connecting piece, wherein the casing is fixedly connected with a platform of a tail oblique beam body of the helicopter and comprises an input end and an output end; the input bevel gear is used for being connected with a tail transmission shaft of the helicopter, is arranged in the case and is positioned at the input end; the output bevel gear is arranged in the casing and meshed with the input bevel gear to form a first-stage speed change mechanism, the output bevel gear is of a hollow structure, and the center line of the output bevel gear is superposed with the center line of the output end and is a first center line; the central line of the tail rotor shaft is coincident with the first central line and can be rotatably installed at the output end, the tail rotor shaft is in transmission connection with the output bevel gear through the planetary transmission assembly to form a two-stage speed change mechanism, the tail rotor shaft is of a hollow structure, and the surface of the tail rotor shaft is provided with a tail rotor installation interface for installing a tail rotor mechanism of a helicopter; the central line of the propeller pitch control shaft is coincident with the first central line and is positioned on one side of the tail propeller shaft, which is far away from the output bevel gear, the propeller pitch control shaft is arranged in the tail propeller shaft, and the propeller pitch control shaft can axially slide and synchronously rotate relative to the tail propeller shaft; booster control rod, booster control rod's central line with first central line coincides mutually, passes in proper order the propeller shaft with output bevel gear, booster control rod adopts the mode that two points of biserial self-aligning ball bearing and sliding sleeve supported, installs inside propeller pitch control shaft to adopt the locking of Suluke nut, through booster control rod drives propeller pitch control shaft follows first central line slides.

According to the scheme, a two-stage speed change system of the helicopter tail speed reducer is formed by an input bevel gear, an output bevel gear, a tail rotor shaft and a planetary transmission assembly; secondly, the technical effect of controlling the propeller pitch of the tail rotor is realized through a propeller pitch control shaft provided with a variable pitch pull rod mounting position and a booster control lever capable of driving the propeller pitch control shaft to slide along the axial direction; and finally, the output bevel gear, the tail propeller shaft and the propeller pitch control shaft are all of hollow structures and are sequentially arranged along the same central line, the complexity of the whole structure is ingeniously simplified, the quality of the whole structure can be effectively reduced, the hollow structure can bear larger torque than a common solid shaft, and the deflection is reduced. In conclusion, on one hand, compared with the traditional helicopter tail reducer, the helicopter tail reducer has higher transmission ratio, lighter weight and higher strength; on the other hand, each part is arranged ingeniously and compactly, and the technical effect of adjusting the pitch is achieved on the premise that the helicopter tail speed reducer uses the two-stage speed change system.

Furthermore, the planetary transmission assembly comprises an inner gear ring, the center line of the inner gear ring is coincident with the first center line, a flange mounting edge is arranged on the outer wall of the inner gear ring, a plurality of first through holes are formed in the flange mounting edge, and the flange mounting edge can be fixedly connected with the casing through threaded connecting pieces; and/or; the thickness of the spoke plate of the inner gear ring is less than 2.5 times of the modulus.

According to the scheme, the inner gear ring in the planetary gear train adopts a thin-wall spoke plate technology, and the thin-wall inner gear ring has smaller rigidity than a common inner gear ring, so that the deformation is larger after load bearing, and the uneven load condition of the planet gears at all positions can be compensated.

Furthermore, the input bevel gear comprises an input bevel gear body, a first gear shaft positioned on the large end side of the input bevel gear body and a second gear shaft positioned on the small end side of the input bevel gear body, a plurality of gear teeth are arranged on the input bevel gear body, the first gear shaft and the second gear shaft are rotatably fixed in the casing, and the first gear shaft can be connected with the tail transmission shaft through a flange plate; the input bevel gear body, the first gear shaft and the second gear shaft are of an integrated structure, and the input bevel gear is mounted in a bearing hole of the casing in a simple support mode of a cylindrical roller bearing, a ball bearing and a roller bearing without an inner ring.

According to the scheme, the input bevel gear structure is creatively designed, the input bevel gear body, the first gear shaft and the second gear shaft are in an integrated structure, in actual assembly, the input bevel gear body is not connected with the gear shafts in a key mode, the bearings are provided with the roller bearings without inner rings, the second gear shaft does not need to be provided with a locking structure to restrain the inner rings of the bearings, assembly difficulty is greatly simplified, and integration level is high.

Furthermore, the output bevel gear comprises an output bevel gear body, a third gear shaft positioned on the large end side of the output bevel gear body and a fourth gear shaft positioned on the small end side of the output bevel gear body, wherein a plurality of gear teeth are arranged on the output bevel gear body, the third gear shaft and the fourth gear shaft are rotatably fixed in the casing, and a plurality of gear teeth are arranged on the surface of the third gear shaft; the output bevel gear body, the third gear shaft and the fourth gear shaft are of an integrated structure.

The scheme of the invention creatively designs the structure of the output bevel gear, and the structure of the existing bevel gear is changed through the integrated output bevel gear main body, the third gear shaft and the fourth gear shaft, so that the existing bevel gear is not fixed through the traditional gear shaft any more, and key connection is not used in actual assembly, thereby simplifying the assembly difficulty to a great extent. In addition, through directly setting up the teeth of a cogwheel on third gear shaft surface, no longer through installing the effect that the external gear just can play sun gear among the planetary transmission subassembly, simple structure integration degree is high.

The tail rotor shaft further comprises a tail rotor shaft main body and a tail rotor shaft flange, the tail rotor shaft flange and the tail rotor shaft main body are located on the same axis, the tail rotor mounting interface is arranged on the tail rotor shaft main body, and the tail rotor shaft flange is provided with a plurality of second through holes so as to assemble the planetary transmission assembly; the tail rotor shaft flange and the tail rotor shaft main body are of an integrated structure; the tail rotor shaft is arranged at the output end in a double-row roller bearing and inner ring-free roller bearing double-pivot supporting mode.

According to the scheme, the tail rotor shaft is further designed, and comprises a tail rotor shaft flange provided with a plurality of second through holes and a tail rotor shaft main body provided with a tail rotor mounting interface, so that on one hand, the tail rotor shaft can be used for fixing a bearing sleeve and is linked with a planetary transmission assembly; on the other hand, the tail rotor mounting interface can be used for mounting a tail rotor of the helicopter and enabling the tail rotor and a tail rotor shaft to rotate synchronously.

Further, the planetary transmission assembly further comprises a first bearing and a bearing sleeve; the bearing sleeve is arranged in the second through hole, an inner ring of the first bearing is in interference fit with the bearing sleeve, a plurality of gear teeth are arranged on the surface of an outer ring of the first bearing, and the first bearing is matched with the inner gear ring and the third gear shaft; wherein the third gear shaft is a sun gear of the planetary transmission assembly; the first bearing is a planetary gear of the planetary transmission assembly; the inner gear ring is an outer gear ring of the planetary transmission assembly; the tail rotor shaft flange is a planet carrier of the planetary transmission assembly.

The invention provides a specific component of a planetary transmission assembly in the tail reducer, a complete planetary transmission mechanism is formed by a first bearing, a third gear shaft, a bearing sleeve, a first bearing and other structures, gear teeth are arranged on the outer ring of the first bearing, and an outer gear of the planetary transmission assembly is formed by matching with an inner gear ring and an output bevel gear. The mode that in traditional structure, at bearing assembly gear has been replaced, convenient actual assembly, and the integration degree is high, has higher reliability.

Furthermore, the casing comprises an input casing, a main casing and an output casing, wherein the main casing is internally provided with an L-shaped channel structure, the input casing and the output casing are respectively installed at two ports of the main casing, and the main casing is fixedly connected with the installation platform of the tail inclined beam body of the helicopter through a threaded connection piece; the input casing is of a disc structure, a bearing mounting hole and a lip-shaped oil seal mounting hole are formed in the center of the input casing, a plurality of mounting holes are formed in the periphery of the input casing, and the input casing can be fixedly connected with the casing main body through threaded connecting pieces; the central line of the output casing coincides with the first central line, the output casing is of a conical hollow structure and is provided with a large end face and a small end face, the large end face extends outwards to form a flange structure, a plurality of mounting holes are formed in the flange, and the main casing, the flange mounting edge and the output casing are sequentially connected through threaded connecting pieces.

The scheme of the invention provides specific components of the main casing, and the main casing, the input casing and the output casing are assembled and connected to achieve the effect of fixing other components. The main box has reasonable structure, and is convenient for the assembly and disassembly of components such as an input bevel gear, an output bevel gear and the like; the input casing is in threaded connection with the main casing and is provided with a bearing mounting hole and a lip-shaped oil seal mounting hole, so that the structure is simple and the reliability is high; the output bevel gear is a conical hollow structure, can fix the propeller shaft on the one hand, and the flange structure of the large end face of the accessible on the other hand is fixedly connected with the main box through a threaded connection piece.

Further, the helicopter tail speed reducer further comprises: the lubricating oil gear pump is fixed in the casing; and the pump gear is fixed at one end of the input bevel gear and is in gear connection with the lubricating oil gear pump.

According to the scheme, the practicability of the tail speed reducer is improved by installing the lubricating oil gear pump, the tail speed reducer has higher integration level, and the input bevel gear or other parts can be effectively lubricated by arranging the pump gear at one end of the input bevel gear.

Furthermore, the first gear shaft is provided with a shaft shoulder, and one end of the shaft shoulder, which is far away from the input bevel gear body, is sequentially provided with the pump gear, a second bearing, a bearing adjusting pad, a third bearing and a flange plate, wherein the flange plate is axially fixed on the first gear shaft through a locking nut, a first clamping ring and a stop ring; the flange plate abuts against the third bearing, and the pump gear abuts against the second bearing so as to clamp the casing and fix the input bevel gear; and/or; an input end lip-shaped oil seal is arranged between the flange plate and the casing, and the input end lip-shaped oil seal is fixed on one side of the third bearing through a second clamping ring.

The scheme of the invention further provides a specific fixing mode of the input bevel gear, and the input bevel gear is axially and radially limited and fixed by arranging the pump gear, the second bearing, the bearing adjusting pad, the third bearing, the flange plate and the locking nut, so that the input bevel gear is reasonable in structure, firm and durable.

A helicopter including a helicopter tail reducer as defined in any one of the above, further comprising: the tail rotor is arranged on the tail rotor mounting interface, and the tail rotor mounting interface is positioned at an external spline of the tail rotor shaft; the pitch control shaft is in transmission connection with the blades of the tail rotor through the pitch control mechanism; the hydraulic oil cylinder is connected with the booster operating rod to drive the booster operating rod to slide along the first center line.

The invention further discloses a helicopter, and the helicopter is provided with the helicopter tail speed reducer, a hydraulic oil cylinder linked with a booster control lever and other structures, so that the technical effects of two-stage speed change and controllable tail rotor pitch of the tail rotor of the helicopter are realized.

The invention has the technical effects that:

1. firstly, forming a two-stage speed change system of a helicopter tail speed reducer through an input bevel gear, an output bevel gear, a tail rotor shaft and a planetary transmission assembly; secondly, the technical effect of changing the pitch of the tail rotor is realized through a pitch control shaft provided with a pitch control pull rod mounting position and a booster control lever capable of driving the pitch control shaft to slide along the axial direction; finally, the output bevel gear, the tail propeller shaft and the propeller pitch control shaft are all of hollow structures and are sequentially arranged along the same central line, the complexity of the whole structure is simplified delicately, the quality of the whole structure can be effectively reduced, and the hollow structure can bear larger torque and reduce deflection compared with a common solid shaft;

2. the thin-wall radial plate technology is used for the inner gear ring in the planetary gear train, and the thin-wall inner gear ring has smaller rigidity than the common inner gear ring, so that the deformation is larger after the load is applied, and the uneven load condition of the planet wheel at each position can be compensated;

3. through the integrated structure of the input bevel gear body, the first gear shaft and the second gear shaft, the input bevel gear body is not connected with the gear shafts in a key mode in actual assembly, so that the assembly difficulty is greatly simplified, and the integration level is high;

4. through output bevel gear main part, third gear shaft and fourth gear shaft integrated into one piece, changed the structure of current bevel gear, it is no longer fixed through traditional gear shaft to make it, need not use the key-type connection in actual assembly, and to a great extent has simplified the assembly degree of difficulty. In addition, the gear teeth are directly arranged on the surface of the third gear shaft, so that the function of a sun gear in the planetary transmission assembly can be realized without installing an external gear, the structure is simple, and the integration degree is high;

5. a complete planetary transmission mechanism is formed by structures such as a first bearing, a third gear shaft, a bearing sleeve, a first bearing and the like, gear teeth are arranged on the outer ring of the first bearing, and an outer gear of the planetary transmission assembly is formed by matching with an inner gear ring and an output bevel gear. The mode of assembling the gear on the bearing in the traditional structure is replaced, so that the gear is convenient to actually assemble, the integration degree is high, and the reliability is higher;

6. the helicopter tail speed reducer has the advantages that the matching relation of all parts is stable, and the parts can be conveniently replaced by combining the standard part with the non-standard part; and on the other hand, the reliability of the whole structure is optimized and is higher.

Drawings

The invention is described in further detail below with reference to the following figures and detailed description:

FIG. 1 is a general cross-sectional view of the device of the present invention;

FIG. 2 is a cross-sectional view of the input end of the apparatus of the present invention;

FIG. 3 is a cross-sectional view of the output end of the apparatus of the present invention;

fig. 4 is a cross-sectional view of the joystick assembly of the present invention.

The reference numbers illustrate:

100. a tail rotor shaft assembly, 200 planetary transmission assemblies, 300 output gear assemblies, 400 casing, 500 input gear assemblies, 600 lubricating oil gear pumps, 700 operating rod assemblies, 1 flange plate, 2 first lock nut, 3 first retainer ring, 4 first stop ring, 5 input casing, 6 input lip oil seal, 7 third bearing, 8 bearing adjusting pad, 9 second bearing, 10 input bevel gear, 11 first inner ring-free roller bearing, 12 blanking cover, 13 pump gear, 14 second retainer ring, 15 roller bearing, 16 three-point ball bearing, 17 output bevel gear, 18 second inner ring-free roller bearing, 19 bearing support plate, 20 inner gear ring, 21 first bearing, 22 bearing sleeve, 23 spacer sleeve, 24 double row tapered roller bearing, 25 output casing, 26 third inner ring-free roller bearing, 27. the third clamping ring 28, the lip oil seal 29, the fourth clamping ring 30, the spline sliding sleeve 31, the first stop pin 32, the propeller shaft 33, the fifth clamping ring 34, the second stop ring 35, the second lock nut 36, the third lock nut 37, the fourth lock nut 38, the third stop ring 39, the sixth clamping ring 40, the sliding sleeve 41, the support plate 42, the main engine box 43, the propeller control shaft 44, the double-row self-aligning ball bearing 45, the fifth lock nut 46, the sixth lock nut 47, the seventh clamping ring 48, the fourth stop ring 49, the second stop pin 50, the sealing plug 50 and the booster control rod 51.

Detailed Description

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following description will be made with reference to the accompanying drawings. It is obvious that the drawings in the following description are only some examples of the invention, and that for a person skilled in the art, other drawings and embodiments can be derived from them without inventive effort.

For the sake of simplicity, only the parts relevant to the invention are schematically shown in the drawings, and they do not represent the actual structure as a product. In addition, in order to make the drawings concise and understandable, components having the same structure or function in some of the drawings are only schematically illustrated or only labeled. In this document, "one" means not only "only one" but also a case of "more than one".

It should be further understood that the term "and/or" as used in this specification and the appended claims refers to and includes any and all possible combinations of one or more of the associated listed items.

In this context, it is to be understood that, unless otherwise explicitly stated or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

In addition, in the description of the present application, the terms "first", "second", and the like are used only for distinguishing the description, and are not intended to indicate or imply relative importance.

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following description will be made with reference to the accompanying drawings. It is obvious that the drawings in the following description are only some examples of the invention, and that for a person skilled in the art, other drawings and embodiments can be derived from them without inventive effort.

[ EXAMPLES one ]

As shown in fig. 1, a tail speed reducer of a helicopter is provided, which can be mounted on a platform of a tail oblique beam body of the helicopter. Firstly, the power generated by an engine in the helicopter is transmitted to the tail reducer of the helicopter through a tail transmission shaft of the helicopter, and finally the power is transmitted to the tail rotor through the speed change and the reversing of the tail reducer of the helicopter. And the blades of the tail rotor are connected with a blade pitch-variable mechanism, and the blade pitch-variable mechanism enables the blade pitch control shaft to be in transmission connection with the blades of the tail rotor, so that the inclination angle of the blades is changed, and the control of the blade pitch is realized.

Further, as shown in fig. 2 and 3, the helicopter tail speed reducer uses the input bevel gear 10 and the output bevel gear 17 which are meshed with each other, and the tail rotor shaft 32 linked with the output bevel gear 17 through the planetary transmission assembly 200, so that the two-stage speed change of the helicopter tail speed reducer is realized, and the pitch control is realized through the pitch control shaft 43 and the slidably arranged booster control lever 51.

Specifically, the helicopter tail reducer has six core components:

a first component: the casing 400 is assembled by the main casing 42, the input casing 5, and the output casing 25 by screw connections. The input and output of the casing 400 correspond to the input casing 5 and the output casing 25, respectively. The main casing 42 may be fixedly connected to the platform of the tail stringer of the helicopter. The input end can be provided with parts such as an input bevel gear 10 and the like, and is indirectly butted with a tail transmission shaft of the helicopter for power input; the output end can be provided with an output bevel gear 17, a tail rotor shaft 32 and other parts, and the parts are indirectly connected with a tail rotor of the helicopter to output power.

It should be noted that, the input casing 5 and the output casing 25 respectively have a center line, and the input end and the output end both have an opening with symmetrical shape to match with the input casing 5 or the output casing 25. Therefore, the normal lines of their opening shapes, or the center lines of the input casing 5 and the output casing 25, are referred to as the center line of the input end and the center line of the output end, respectively. And the central line of the output end is defined as a first central line, and the central line of the input end is defined as a second central line. In the drawings of the present embodiment, the first center line is perpendicular to the second center line, and in addition, a certain angle is allowed to exist between the first center line and the second center line, and all of them belong to the protection scope of the present invention.

A second component: and the input bevel gear 10 is arranged in the casing 400, the central line of the input bevel gear 10 is coincident with the second central line and is positioned at the input end, and the two ends of the input bevel gear 10 are respectively fixed with the main casing 42 through the input casing 5. One end of the input bevel gear 10 is fixed with a flange 1, and the flange 1 can be connected with a tail transmission shaft.

A third component: the output bevel gear 17 is installed in the casing 400, the center line of the output bevel gear 17 coincides with the first center line, the output bevel gear 17 is engaged with the input bevel gear 10 to form a first-stage speed change mechanism, and the output bevel gear 17 has a hollow structure. And one end of the output bevel gear 17 far away from the input bevel gear 10, i.e. the large end of the output bevel gear 17 in the figure, is provided with a third gear shaft, and the surface of the third gear shaft is provided with gear teeth which can be matched with the gear teeth of the first bearing 21 in the following description to form a sun gear of the planetary transmission assembly 200.

And a fourth component: the center line of the tail rotor shaft 32 coincides with the first center line, the tail rotor shaft is rotatably fixed at the output end in a double-row roller bearing and inner ring-free roller bearing double-pivot supporting mode, the tail rotor shaft can be divided into a tail rotor shaft main body and a tail rotor shaft flange according to functions, and the tail rotor shaft flange and the tail rotor shaft main body are located on the same axis and are of an integrated hollow structure. The tail rotor shaft body is provided with a tail rotor mounting interface for mounting a tail rotor of a helicopter, and the tail rotor shaft flange is provided with a plurality of second through holes for mounting a bearing sleeve 22 in the future to form a planet carrier of the planetary transmission assembly 200. In other words, the tail rotor shaft 32 is drivingly connected to the output bevel gear 17 through the planetary drive assembly 200 to form a two-stage transmission mechanism.

Part five: the pitch steering shaft 43, the center line of which coincides with the first center line, is located on the side of the tail rotor shaft 32 remote from the output bevel gear 17. The pitch control shaft 43 can be divided into two sections according to whether the pitch control shaft is sleeved in the tail rotor shaft 32. One section is arranged in the tail propeller shaft 32 through the spline sliding sleeve 30, the other section is arranged outside the tail propeller shaft 32, and the surface of the other section is provided with a variable-pitch pull rod mounting position which can be used for directly or indirectly mounting a variable-pitch pull rod.

It should be noted that, the spline sliding sleeve 30 is also called a spline sliding tube, on one hand, the spline on the sliding sleeve can ensure that the tail rotor shaft 32 and the pitch control shaft 43 rotate synchronously, and on the other hand, the pitch control shaft 43 can slide relatively along the axial direction of the tail rotor shaft 32. Therefore, in the high-speed rotation state of the tail rotor shaft 32, the pitch control shaft 43 rotates at the same rotational speed, and both are kept stationary. The slippage of the pitch control shaft 43 along the axial direction thereof does not affect the tail rotor shaft 32, so that the pitch control shaft 43 can change the pitch through the variable pitch pull rod in the rotating state, and therefore, the pitch control shaft 43 and the tail rotor shaft 32 can realize axial slippage and synchronous rotation.

A sixth component: and a booster operating lever 51, the center line of which coincides with the first center line, sequentially penetrates through the tail rotor shaft 32, the output bevel gear 17 and the casing 400, a gap is formed between the booster operating lever 51 and the tail rotor shaft 32 to install the pitch control shaft 43, and the booster operating lever 51 can drive the pitch control shaft 43 to slide along the first center line so as to change the blade inclination angle of the tail rotor through the variable pitch pull rod.

As shown in fig. 4, a shoulder is disposed at an end of the booster operating lever 51 away from the output bevel gear 17, and a step is disposed at a position corresponding to the pitch control shaft 43. The end of the booster operating rod 51 is fixedly provided with a sixth locking nut 46, a seventh clamping ring 47 and a fourth stop ring 48, wherein the inner ring of the double-row self-aligning ball bearing 44 is in interference fit with the booster operating rod 51 and is locked by the sixth locking nut 46, the fourth stop ring 48 prevents the locking nut from loosening, and the seventh clamping ring 47 axially restrains the fourth stop ring 48. The inner surface of the pitch control shaft 43 is in interference fit with the outer ring of the double-row self-aligning ball bearing 44, and is locked by a fifth locking nut 45, and the locking nut is prevented from loosening by using a split pin 49. It is thereby achieved that pitch control shaft 43 is movable in the axial direction together with booster control lever 51.

Further preferably, the planetary transmission assembly 200 further comprises an inner gear ring 20, a first bearing 21 and a bearing sleeve 22; the inner gear ring 20 is fixedly connected with the casing 400 to form an outer gear ring of the planetary transmission assembly 200; the third gear shaft of the output bevel gear 17 is located at the same center line as the ring gear 20 to form a sun gear of the planetary transmission assembly 200. Preferably, the bearing sleeve 22 is fixedly connected with the tail rotor shaft 32, and the outer ring of the first bearing 21 is provided with gear teeth and is matched with the inner ring gear 20 and the output bevel gear 17 to form a planetary gear of the planetary transmission assembly 200. Specifically, the first bearing 21 is sleeved on the outer surface of the bearing sleeve 22, one end of the bearing sleeve 22 is provided with a step, the other end of the bearing sleeve 22 is provided with a spacer 23 and a third locking nut 36, and the third locking nut 36 is in threaded connection with the bearing sleeve 22 to fix the first bearing 21.

Specifically, the inner gear ring 20 is a tubular structure, one end of the inner wall of the inner gear ring 20 is provided with a plurality of gear teeth, the outer wall of one end of the inner gear ring 20 away from the gear teeth is provided with a flange mounting edge, and the flange mounting edge is provided with a plurality of through holes which can be matched with the casing 400; preferably, the thickness of the web plate of the inner gear ring 20 is less than 2.5 times of the modulus to form a thin-wall web plate structure, it should be noted that the thickness of the web plate of the common gear ring is about 2.5 to 5 times of the modulus, so that the load-sharing characteristic is unstable when the planet gears work, and the thin-wall inner gear ring 20 deforms more after being loaded because the rigidity is smaller than that of the common inner gear ring, so that the uneven load condition of the planet gears at each position can be compensated.

In practical application, on one hand, a helicopter engine is connected with a tail transmission shaft, and the tail transmission shaft transmits power to an input bevel gear 10 through a flange plate 1; the input bevel gear 10 and the output bevel gear 17 are meshed with each other, and power is transmitted to the output bevel gear 17; the output bevel gear 17, in turn, acts as a sun gear for the planetary transmission assembly 200, transmitting power to the first bearing 21; the first bearing 21, in turn, acts as a planetary gear for the planetary transmission assembly 200, transmitting power to the bearing sleeve 22 and to the tail shaft 32; the tail rotor shaft 32 is provided with a tail rotor mounting interface, and finally transmits power to the tail rotor.

On the other hand, the hydraulic oil cylinder of the helicopter is connected with the booster operating rod 51, and the hydraulic oil cylinder directly or indirectly drives the booster operating rod 51 to move along the axial direction thereof; the booster operating rod 51 is in bearing connection with the pitch control shaft 43, and the booster operating rod 51 drives the pitch control shaft 43 to move along the axial direction of the pitch control shaft; the pitch control shaft 43 is directly or indirectly connected with a pitch-variable pull rod or other blade pitch-variable mechanisms to drive the pitch-variable pull rod or other blade pitch-variable mechanisms to push and pull the helicopter tail rotor blades, so as to change the pitch of the blades and realize pitch control.

[ example two ]

As shown in fig. 1, the helicopter tail reducer mainly includes five components, including a casing 400, and an input gear assembly 500, an output gear assembly 300, a tail rotor shaft assembly 100 and a planetary transmission assembly 200 disposed inside the casing 400, it should be noted that the casing 400 does not completely accommodate other components inside, for example, the tail rotor shaft assembly 100 is partially disposed inside the casing 400, and the casing 400 plays a role of connecting, fixing and protecting other components.

Specifically, the input gear assembly 500 includes an input bevel gear 10 and components for fixing the input bevel gear 10, such as a first lock nut 2, a flange plate 1, a first collar 3, a second collar 14, a cylindrical roller bearing, a bearing adjusting pad 8, a second bearing 9, a first stop ring 4, a cap 12, a first inner-ring-free roller bearing 11, and the like. Likewise, the output gear assembly 300 includes the output bevel gear 17 and components for fixing the input bevel gear 10, such as the second inner-ring-less roller bearing 18, the three-point ball bearing 16, the roller bearing, the fourth lock nut 37, the third snap ring 38, and the fifth snap ring 33.

Further, the input bevel gear 10 and the output bevel gear 17 are rotatably fixed inside the casing 400 and are engaged with each other, and preferably, the axes of the input bevel gear 10 and the output bevel gear 17 are perpendicular to each other; the tail rotor shaft assembly 100 is arranged at one end, far away from the input bevel gear 10, of the output bevel gear 17 and is in transmission connection with the output bevel gear 17 through the planetary transmission assembly 200, a tail rotor installation interface is arranged on the tail rotor shaft assembly 100, the tail rotor installation interface is located at an external spline of the tail rotor shaft 32, and a tail rotor of a helicopter can be installed on the tail rotor installation interface.

In a preferred embodiment, the output bevel gear 17, the tail shaft 32 and the booster operating lever 51 are all hollow and located on the same axis. The helicopter tail reducer also includes a joystick assembly 700; the control rod assembly 700 further comprises a pitch control shaft 43, a booster control rod 51 and other components, wherein the surface of the pitch control shaft 43 is connected with the inner surface of the tail rotor shaft 32 in a sliding way, and a blade pitch-changing mechanism connecting position is arranged on the pitch control shaft 43; the booster lever 51 has one end rotatably connected to the pitch control shaft 43 and the other end connected to the casing 400 through the tail shaft 32 and the output bevel gear 17 in turn, and the lever assembly 700 is movable in the axial direction thereof. Preferably, the surface of the pitch control shaft 43 is connected with the inner surface of the tail rotor shaft 32 through a spline sliding sleeve 30, the spline sliding sleeve 30 is fixed on the inner surface of the tail rotor shaft 32 through a first stop pin 31, the control lever assembly 700 can move along the axial direction of the tail rotor shaft 32 under the action of the spline sliding sleeve 30, the pitch control shaft 43 in the control lever assembly 700 can rotate synchronously with the tail rotor shaft 32, and further, the blade pitch control mechanism of the tail rotor is connected with the pitch control lever, and the purpose of adjusting the pitch of the tail rotor is achieved through the axial movement of the control lever assembly 700.

Specifically, a seventh collar 47, a fourth stop ring 48, a second stop pin 49, a fifth lock nut 45, a sixth lock nut 46, a double-row self-aligning ball bearing 44, a sealing plug 50 and the like are sequentially arranged between the booster operating lever 51 and the pitch operating shaft 43; a sliding sleeve 40 is arranged between one end of the booster operating rod 51 far away from the pitch operating shaft 43 and the casing 400, the sliding sleeve 40 is fixed in a through hole of the supporting plate 41, and the supporting plate 41 is of a conical structure.

Further preferably, the input bevel gear 10 includes an input bevel gear body, a first gear shaft located at a large end side, and a second gear shaft located at a small end side, the input bevel gear body is provided with a plurality of gear teeth, and the input bevel gear 10 is an integrated hollow structure. It should be noted that, in the conventional reducer structure, the bevel gear is fixed on the gear shaft through a key, but in the present invention, the bevel gear and the gear shaft are designed into an integrated structure through simulation analysis, so as to obtain higher structural strength and lighter weight.

Furthermore, the first gear shaft and the second gear shaft are rotatably fixed inside the casing 400, a flange 1 is fixed at one end of the first gear shaft away from the second gear shaft, a plurality of input end connection positions are arranged on the flange 1, and the preferred input end connection positions are through holes and can be fixedly connected with an external input shaft through threaded connection pieces.

Similarly, the output bevel gear 17 includes an output bevel gear body, a third gear shaft located on the large end side, and a fourth gear shaft located on the small end side, and the output bevel gear body is provided with a plurality of gear teeth, which are of an integral hollow structure. The structure of the input bevel gear 10 is similar to an integrated structure, and it should be noted that the gear teeth arranged on the output bevel gear 17 should be matched with the gear teeth of the input bevel gear 10, and the number of the gear teeth is different to achieve the purpose of speed change.

Furthermore, the third gear shaft and the fourth gear shaft are rotatably fixed inside the casing 400, and a plurality of gear teeth are disposed on one end of the third gear shaft away from the fourth gear shaft, and can be engaged with the planetary transmission assembly 200. It should be noted that the third gear shaft and the fourth gear shaft are supported and fixed by using a double-fulcrum second non-inner-ring roller bearing 18, a three-point ball bearing 16 and a roller bearing 15, the second non-inner-ring roller bearing 18 is fixed by a bearing support plate 19, the output bevel gear 17 can rotate in the casing 400 due to the structural characteristics of the bearings, wherein the three-point ball bearing 16 and the roller bearing 15 are locked by a fourth lock nut 37, the second stop ring 38 prevents the lock nut from loosening, and the sixth stop ring 39 axially restrains the second stop ring 38.

Further preferably, the planetary transmission assembly 200 further comprises an inner gear ring 20, a first bearing 21 and a bearing sleeve 22; the ring gear 20 is fixedly connected with the casing 400 to form a ring gear of the planetary transmission assembly 200; the third gear shaft is located at the same center line as the ring gear 20 to form a sun gear of the planetary transmission assembly 200. Preferably, the bearing sleeve 22 is fixedly connected with the tail rotor shaft assembly 100, and the outer ring of the first bearing 21 is provided with gear teeth and is matched with the inner ring gear 20 and the output bevel gear 17 to form an outer gear of the planetary transmission assembly 200. Specifically, the first bearing 21 is sleeved on the outer surface of the bearing sleeve 22, one end of the bearing sleeve 22 is provided with a step, the other end of the bearing sleeve 22 is provided with a spacer 23 and a third locking nut 36, and the third locking nut 36 is in threaded connection with the bearing sleeve 22 to fix the first bearing 21.

Specifically, the inner gear ring 20 is a tubular structure, one end of the inner wall of the inner gear ring 20 is provided with a plurality of gear teeth, the outer wall of one end of the inner gear ring 20 away from the gear teeth is provided with a flange mounting edge, and the flange mounting edge is provided with a plurality of through holes which can be matched with the casing 400; preferably, the thickness of the web plate of the inner gear ring 20 is less than 2.5 times of the modulus to form a thin-wall web plate structure, it should be noted that the thickness of the web plate of the common gear ring is about 2.5 to 5 times of the modulus, so that the load-sharing characteristic is unstable when the planet gears work, and the thin-wall inner gear ring 20 deforms more after being loaded because the rigidity is smaller than that of the common inner gear ring, so that the uneven load condition of the planet gears at each position can be compensated.

In a preferred embodiment, the tail rotor shaft assembly 100 comprises a tail rotor shaft 32 and other components for fixing the tail rotor shaft 32, such as a double row roller bearing 24, a second lock nut 35, a stop ring 34, a fifth collar 33, a third inner ring-free roller bearing 26, a third collar 27, a lip oil seal 28, a fourth collar 29, a spline sliding sleeve 30 arranged at one end of the tail rotor shaft 32 far away from the output bevel gear 17, and a first stop pin 31 for axially fixing the spline sliding sleeve 30. Preferably, the tail shaft 32 is rotatably connected to the case 400 by a double row tapered roller bearing 24.

The tail rotor shaft 32 further comprises a tail rotor shaft main body and a tail rotor shaft flange, the tail rotor shaft flange and the tail rotor shaft main body are located on the same axis, the tail rotor shaft flange is provided with a plurality of bearing sleeve fixing positions parallel to the axis, and one end of the tail rotor shaft main body, far away from the tail rotor shaft flange, is provided with an operating rod assembly 700 fixing position, namely used for setting the spline sliding sleeve 30. Preferably, the bearing sleeve fixing locations are through holes into which the bearing sleeve 22 can be inserted and fixed using a fourth lock nut 37.

Preferably, the casing 400 includes a main casing 42, an input casing 5 and an output casing 25, the main casing 42 is an L-shaped channel structure, and the input casing 5 and the output casing 25 are respectively fixed at two ports of the main casing 42 to mount and fix the input gear assembly 500 and the tail rotor shaft assembly 100. Further preferably, the output casing 25 is a tapered hollow structure, the large end face and the small end face of the output casing 25 are respectively provided with a corresponding tail rotor shaft limiting hole and a corresponding tail rotor shaft positioning hole, the large end face extends outwards to form a flange structure, and the flange is provided with a plurality of through holes and can be fixedly connected with the main casing 42 through threaded connectors. Specifically, the input casing 5 is a disk structure, the center of the input casing 5 is provided with a bearing mounting hole and a lip-shaped oil seal mounting hole, and the periphery of the input casing 5 is provided with a plurality of through holes which can be fixedly connected with the main casing 42 through a threaded connection piece. The main casing 42 is fixedly connected with the mounting platform of the tail oblique beam body of the helicopter through screws and nuts.

In a preferred embodiment, the helicopter tail speed reducer further comprises an oil gear pump 600, and the oil gear pump 600 is fixed inside the casing 400. Preferably, the input gear assembly 500 further includes a pump gear 13, and the pump gear 13 is fixed to one end of the input bevel gear 10, i.e., the outer surface of the first gear shaft, and is in gear connection with the oil gear pump 600.

Specifically, a shaft shoulder is arranged on the large end side of the input bevel gear 10, and a pump gear 13, a second bearing 9, a bearing adjusting pad 8, a third bearing 7, an input end lip oil seal 6, a flange plate 1, a first clamping ring 3, a stop ring 4 and a first locking nut 2 are sequentially arranged at one end of the shaft shoulder far away from the output bevel gear 17. Preferably, the third bearing 7 is a cylindrical roller bearing and the second bearing 9 is a ball bearing. Further, the outer ring of the second bearing 9 is provided with a flange to be fitted with the casing 400, and a gap is formed between the second bearing 9 and the shoulder to fix the pump gear 13. Further, a gap is provided between the first lock nut 2 and the second bearing 9 to fix the bearing adjusting pad 8, the third bearing 7, and the flange 1.

In practical application, on one hand, a helicopter engine is connected with a tail transmission shaft, and the tail transmission shaft transmits power to an input bevel gear 10 through a flange plate 1; the input bevel gear 10 and the output bevel gear 17 are meshed with each other, and power is transmitted to the output bevel gear 17; the output bevel gear 17, in turn, acts as a sun gear for the planetary transmission assembly 200, transmitting power to the first bearing 21; the first bearing 21, in turn, acts as a planetary gear for the planetary transmission assembly 200, transmitting power to the bearing sleeve 22 and to the tail shaft 32; the tail rotor shaft 32 is provided with a tail rotor mounting interface, and finally transmits power to the tail rotor.

On the other hand, the hydraulic oil cylinder of the helicopter is connected with the booster operating rod 51, and the hydraulic oil cylinder directly or indirectly drives the booster operating rod 51 to move along the axial direction thereof; the booster operating rod 51 is in bearing connection with the pitch control shaft 43, and the booster operating rod 51 drives the pitch control shaft 43 to move along the axial direction of the pitch control shaft; the pitch control shaft 43 is directly or indirectly connected with a pitch-variable pull rod or other blade pitch-variable mechanisms to drive the pitch-variable pull rod or other blade pitch-variable mechanisms to push and pull the helicopter tail rotor blades, so as to change the pitch of the blades and realize pitch control.

[ EXAMPLE III ]

A helicopter is provided with a tail reducer of the helicopter in embodiment 1 or embodiment 2, and is further provided with a tail rotor, a blade pitch varying mechanism and a hydraulic oil cylinder, wherein the hydraulic oil cylinder is connected with a booster operating rod 51 to drive the booster operating rod 51 to slide along the axial direction of the booster operating rod, and then the blade pitch varying mechanism is linked with the blades of the tail rotor to change the blade inclination angle of the blades of the tail rotor.

In practical application, on one hand, power generated by an engine in the helicopter is transmitted to a tail reducer of the helicopter through a tail transmission shaft, and finally the power is transmitted to a tail rotor of the helicopter through speed change and reversing of the tail reducer of the helicopter; on the other hand, the booster control rod 51 is driven to slide along the axial direction of the booster control rod by controlling the extension and contraction of the hydraulic oil cylinder, the propeller pitch control shaft 43 moves synchronously along with the axial direction of the booster control rod 51, and finally the propeller pitch control mechanism is driven to move so as to adjust the propeller pitch of the helicopter tail rotor and change the propeller pitch.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.