A tail drive shaft structure for helicopters

Abstract

This invention discloses a tail drive shaft structure for a helicopter, comprising a tail tube, a tail drive shaft, a tail gear reducer, a flexible coupling assembly, and a support plate. The tail drive shaft is disposed inside the tail tube, with one end connected to the flexible coupling assembly and the other end connected to the tail gear reducer. The tail drive shaft is connected to the inner hole of the support plate via a bearing. The invention is characterized by a follower impeller mounted on the tail drive shaft. The follower impeller is located inside the tail tube and positioned closer to the flexible coupling assembly. The tail tube is a through-tube. The follower impeller is used to allow airflow within the tail tube to flow from one end of the tail gear reducer to one end of the flexible coupling assembly, thereby reducing the impact of unwanted airflow (turbulence, disturbance) on the tail rotor and tail fin, and thus improving their operational stability.

Description

Technical Field

[0001] This invention relates to the field of helicopter technology, and more specifically to a tail drive shaft structure for a helicopter. Background Technology

[0002] The existing tail drive shaft structure for helicopters includes a tail tube, a tail drive shaft, a tail gear reducer, a flexible coupling assembly, and support plates. The tail drive shaft is located inside the tail tube, with one end connected to the flexible coupling assembly and the other end connected to the tail gear reducer. The tail drive shaft is connected to the inner hole of the support plate via bearings. Multiple support plates are arranged in an array along the axial direction of the tail drive shaft, and the outer periphery of the support plates is connected to the inner wall of the tail tube. However, the existing tail drive shaft structure still suffers from the significant impact of undesirable airflow (such as turbulence and disturbance) on the tail rotor and tail fin, and its operational stability needs further improvement. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a tail drive shaft structure for helicopters. Its follower impeller is used to direct airflow within the tailpipe from one end of the tail reducer to the other end of the flexible coupling assembly, thereby reducing the impact of unwanted airflow (such as turbulence and disturbance) on the tail rotor and tail fin, and thus improving operational stability. Its adjusting collar, which is axially and circumferentially positionable relative to the hub, is installed in a groove to adjust the airflow pattern at the root of the main blades. This allows for improved airflow / ventilation from the tail reducer side to the flexible coupling assembly side, while maintaining a constant tail drive shaft speed.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0005] A tail drive shaft structure for a helicopter includes a tail tube, a tail drive shaft, a tail gear reducer, a flexible coupling assembly, and support plates. The tail drive shaft is disposed inside the tail tube, with one end connected to the flexible coupling assembly and the other end connected to the tail gear reducer. The tail drive shaft is connected to the inner hole of the support plates via bearings. Multiple support plates are arranged in an array along the axial direction of the tail drive shaft, and the outer periphery of the support plates is connected to the inner wall of the tail tube. The characteristic feature is that a follower impeller is mounted on the tail drive shaft. The follower impeller is located inside the tail tube and is positioned closer to the flexible coupling assembly. The tail tube is a through-tube. The follower impeller is used to cause the airflow inside the tail tube to flow from one end of the tail gear reducer to one end of the flexible coupling assembly, thereby reducing the impact of unwanted airflow on the tail rotor and tail fin.

[0006] Furthermore, the follower impeller includes a hub, main blades, small blades, an adjusting collar, and a groove. The hub is sleeved on the tail drive shaft. Multiple main blades are arranged circumferentially on the outer circumferential surface of the hub. Multiple small blades are arranged circumferentially on the outer circumferential surface of the adjusting collar. The small blades are located at the upstream end of the main blades. A groove is opened on the outer circumferential surface of the upstream end of the hub. The adjusting collar is installed in the groove in an adjustable position relative to the hub.

[0007] Furthermore, the adjusting collar is installed in the groove with its axial position adjustable relative to the hub. The adjusting collar has multiple radial mounting holes distributed circumferentially. The hub has multiple first adjusting threaded holes located in the groove, arranged in an axial array. After adjusting the axial mounting position of the adjusting collar and the small blade, the adjusting screw passes through the radial mounting holes and connects with the first adjusting threaded holes.

[0008] Furthermore, in the axial direction, there is an axial gap between the intersection of the tip and trailing edges of the small blade and the leading edge of the corresponding main blade, and this axial gap is adjustable.

[0009] Furthermore, the projections of the small blade and the main blade in the cross section through the axis do not intersect or overlap.

[0010] Furthermore, the adjusting collar is installed in the groove in an adjustable circumferential position relative to the hub. Multiple second adjusting threaded holes are provided on the hub and located in the groove. The multiple second adjusting threaded holes are arranged in a circumferential array. After adjusting the circumferential installation position of the adjusting collar and the small blade, the adjusting screw passes through the radial mounting hole and connects with the second adjusting threaded holes.

[0011] Furthermore, in the circumferential direction, there is a circumferential gap between the small blade and the adjacent main blade, and this circumferential gap is adjustable.

[0012] Furthermore, the radial height of the small blade is less than 35% of the radial height of the main blade.

[0013] Furthermore, the axial width of the small blade is less than 35% of the axial width of the main blade.

[0014] The tail drive shaft structure of a helicopter according to the present invention has the following beneficial technical effects:

[0015] (1) The follower impeller is used to make the airflow in the tailpipe flow from one end of the tail reducer to one end of the flexible coupling assembly, so as to reduce the impact of unwanted airflow (such as turbulence and disturbance) on the tail rotor and tail fin, thereby improving its operational stability.

[0016] (2) The adjusting collar is installed in the groove with adjustable axial and circumferential positions relative to the hub, which can adjust the airflow state at the root of the main blade, thereby improving the airflow / air delivery effect of the follower impeller from the tail reducer side to the flexible coupling assembly side under the premise that the tail drive shaft speed is constant. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the tail drive unit of the helicopter of the present invention;

[0018] Figure 2 This is a schematic diagram of the tail drive shaft structure of the helicopter of the present invention;

[0019] Figure 3 This is a schematic diagram of the first adjustment position structure of the follower impeller of the tail drive shaft structure of the helicopter of the present invention;

[0020] Figure 4 This is a schematic diagram of the second adjustment position structure of the follower impeller of the tail drive shaft structure of the helicopter of the present invention.

[0021] In the diagram: Tailpipe 1, Tail drive shaft 2, Tail reducer 3, Flexible coupling assembly 4, Support plate 5, Follower impeller 6, Hub 61, Main blade 62, Small blade 63, Adjusting collar 64, Groove 65, Adjusting threaded hole 66, Adjusting screw 67, Clearances G1, G2. Detailed Implementation

[0022] To make the technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described in a clearer and more complete manner below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only some embodiments of the present invention, and are only used to explain the present invention, not to limit the present invention. It should be noted that, for ease of description, only the parts / structures related to the present invention are shown in the accompanying drawings. Other related parts can be referred to with ordinary design. In the absence of conflict, the embodiments and technical features in the embodiments of the present invention can be combined with each other to obtain new embodiments.

[0023] Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this invention. Furthermore, unless otherwise defined, the technical or scientific terms used in the description of this invention should have the ordinary meaning understood by those skilled in the art.

[0024] The present invention will now be described in further detail with reference to the accompanying drawings.

[0025] like Figure 1-4As shown, a tail drive shaft structure for a helicopter includes a tail tube 1, a tail drive shaft 2, a tail reducer 3, a flexible coupling assembly 4, and a support plate 5. The tail drive shaft 2 is disposed inside the tail tube 1, with one end connected to the flexible coupling assembly 4 and the other end connected to the tail reducer 3. The tail drive shaft 2 is connected to the inner hole of the support plate 5 via a bearing. Multiple support plates 5 are arranged in an array along the axial direction of the tail drive shaft 2, and the outer periphery of the support plate 5 is connected to the inner wall of the tail tube 1. The characteristic feature is that a follower impeller 6 is mounted on the tail drive shaft 3. The follower impeller 6 is located inside the tail tube 1 and is positioned closer to the side of the flexible coupling assembly 4. The tail tube 1 is a through-tube, and the follower impeller 6 is used to cause the airflow in the tail tube 1 to flow from one end of the tail reducer 3 to one end of the flexible coupling assembly 4 (the airflow is as follows...). Figure 2 (As shown by the middle arrow) to reduce the impact of unwanted airflow (such as turbulence and disturbance) on the tail rotor and tail fin, thereby improving their operational stability.

[0026] In one embodiment, the follower impeller 6 includes a hub 61, main blades 62, small blades 63, an adjusting collar 64, and a groove 65. The hub 61 is sleeved on the tail drive shaft 2. The outer circumferential surface of the hub 61 is provided with a plurality of circumferentially distributed main blades 62. The outer circumferential surface of the adjusting collar 64 is provided with a plurality of circumferentially distributed small blades 63. The small blades 63 are located at the upstream end of the main blades 62. The outer circumferential surface at the upstream end of the hub 61 is provided with a groove 65. The adjusting collar 64 is installed in the groove 65 in an adjustable position relative to the hub 61.

[0027] The adjusting collar 64 is installed in the groove 65 with its axial position adjustable relative to the hub 61. Specifically, the adjusting collar 64 has multiple radial mounting holes distributed circumferentially. The hub 61 has multiple first adjusting threaded holes 66 located in the groove 65, arranged in an axial array. After adjusting the axial mounting positions of the adjusting collar 64 and the small blade 63, the adjusting screw 67 passes through the radial mounting holes and connects to the first adjusting threaded holes 66 to fix the adjusting collar 64. The adjusting collar 64, with its axial position adjustable relative to the hub 61 and installed in the groove 65, can adjust the airflow pattern at the root of the main blade 62, thereby improving the airflow / ventilation effect of the follower impeller 6 from the tail reducer 3 side to the flexible coupling assembly 4 side, provided that the tail drive shaft 2 rotates at a constant speed.

[0028] Furthermore, in the axial direction, there is an axial gap (G1, G2) between the intersection of the tip and trailing edges of the small blade 63 and the leading edge of the corresponding main blade 62, which is adjustable.

[0029] The projections of the small blade 63 and the main blade 62 in the cross section through the axis do not intersect or overlap, such as... Figure 3-4 As shown.

[0030] In one embodiment, the adjusting collar 64 is installed in the groove 65 with its circumferential position adjustable relative to the hub 61. Specifically, the hub 61 has a plurality of second adjusting threaded holes located in the groove 65, which are arranged in a circumferential array. After adjusting the circumferential installation position of the adjusting collar 64 and the small blade 63, the adjusting screw 67 passes through the radial mounting hole and connects to the second adjusting threaded holes to fix the adjusting collar 64. The adjusting collar 64, with its circumferential position adjustable relative to the hub 61 and installed in the groove 65, can adjust the airflow pattern at the root of the main blade 62, thereby further improving the airflow / air delivery effect of the follower impeller 6 from the tail reducer 3 side to the flexible coupling assembly 4 side, provided that the tail drive shaft 2 rotates at a constant speed.

[0031] Furthermore, in the circumferential direction, there is a circumferential gap between the small blade 63 and the adjacent main blade 62, which is adjustable.

[0032] Furthermore, the radial height of the small blade 63 is less than 35% of the radial height of the main blade 62.

[0033] The axial width of the small blade 63 is less than 35% of the axial width of the main blade 62.

[0034] The present invention discloses a tail drive shaft structure for a helicopter. An adjusting collar 64 is installed in a groove 65 with adjustable axial and circumferential positions relative to the hub 61. This can adjust the airflow pattern at the root of the main blade 62, thereby improving the induced draft / blowing effect of the follower impeller 6 from the tail reducer 3 side to the flexible coupling assembly 4 side under the premise that the tail drive shaft 2 rotates at a constant speed.

[0035] The tail drive shaft structure of a helicopter according to the present invention has the following beneficial technical effects:

[0036] (1) The follower impeller 6 is used to make the airflow in the tailpipe 1 flow from one end of the tail reducer 3 to one end of the flexible coupling assembly 4 (the airflow is as follows). Figure 2 (As shown by the middle arrow) to reduce the impact of unwanted airflow (such as turbulence and disturbance) on the tail rotor and tail fin, thereby improving their operational stability.

[0037] (2) The adjusting collar 64 is installed in the groove 65 with its axial and circumferential positions adjustable relative to the hub 61. It can adjust the airflow state at the root of the main blade 62, thereby improving the airflow / air delivery effect of the follower impeller 6 from the tail reducer 3 side to the elastic coupling assembly 4 side under the premise that the tail drive shaft 2 rotates at a constant speed.

[0038] The above embodiments are illustrative of the present invention and not intended to limit the invention. It is understood that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the invention. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A tail drive shaft structure for a helicopter, comprising a tail tube (1), a tail drive shaft (2), a tail reducer (3), a flexible coupling assembly (4), and a support plate (5), wherein the tail drive shaft is disposed inside the tail tube, one end of the tail drive shaft is connected to the flexible coupling assembly, and the other end is connected to the tail reducer; the tail drive shaft is connected to the inner hole of the support plate via a bearing; multiple support plates are arranged in an array along the axial direction of the tail drive shaft, and the outer periphery of the support plate is connected to the inner wall of the tail tube; characterized in that: A follower impeller (6) is installed on the tail drive shaft. The follower impeller is located inside the tail tube and is positioned on the side close to the flexible coupling assembly. The tail tube is a through tube. The follower impeller is used to make the airflow in the tail tube flow from one end of the tail reducer to one end of the flexible coupling assembly, so as to reduce the impact of unwanted airflow on the tail rotor and tail fin. The follower impeller includes a hub (61), main blades (62), small blades (63), adjusting ring (64), and groove (65). The hub is sleeved on the tail drive shaft. Multiple main blades are arranged circumferentially on the outer circumferential surface of the hub. Multiple small blades are arranged circumferentially on the outer circumferential surface of the adjusting ring. The small blades are located at the upstream end of the main blades. A groove is opened on the outer circumferential surface of the upstream end of the hub. The adjusting ring is installed in the groove in an adjustable position relative to the hub. The adjusting collar is installed in the groove with its axial position adjustable relative to the hub. The adjusting collar has multiple radial mounting holes distributed circumferentially. The hub has multiple first adjusting threaded holes located in the groove, arranged in an axial array. After adjusting the axial mounting position of the adjusting collar and the small blade, the adjusting screw passes through the radial mounting holes and connects to the first adjusting threaded holes. In the axial direction, there is an axial gap (G1, G2) between the intersection of the tip and trailing edges of the small blade and the corresponding leading edge of the main blade. This axial gap is adjustable. The adjusting collar is installed in the groove in a way that allows its circumferential position to be adjusted relative to the hub. Multiple second adjusting threaded holes are provided on the hub and located in the groove. The multiple second adjusting threaded holes are arranged in a circumferential array. After adjusting the circumferential installation position of the adjusting collar and the small blade, the adjusting screw passes through the radial mounting hole and connects to the second adjusting threaded hole. In the circumferential direction, there is a circumferential gap between the small blade and the adjacent main blade, and this circumferential gap is adjustable.

2. The tail drive shaft structure of a helicopter as described in claim 1, characterized in that, The projections of the small blades and the main blades in the cross section through the axis do not intersect or overlap.

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