Lightning protection ram air turbine system

Abstract

A ram air turbine system is applied to an aircraft and includes a turbine, a generator, and turbine blades. A blade insulating piece is arranged at the connecting position between the turbine blade and a shell of the turbine, and a high-resistance lining is arranged at the connecting position of the turbine blade and a gearbox or at the portion close to the connecting position of the turbine blade and the gearbox. The ram air turbine system with the structure can reduce the damage of lightning stroke to the generator, and can improve the efficiency of the generator.

Description

Technical Field

[0001] The present application relates to the field of aircraft design, and in particular to the lightning protection structure design of a ram air turbine system of an aircraft. Background Art

[0002] The ram air turbine (RAT) system is an important component of the aircraft. When the aircraft engine stops and the auxiliary power system fails completely, it can provide power to the cockpit and flight control system driven by the ram pressure generated during the flight of the aircraft, so as to ensure the safe landing of the aircraft to the minimum extent.

[0003] During the flight of the aircraft, when the RAT system is lowered and faces the airflow, the RAT system may be struck by lightning in the high altitude. The types of lightning include negative ground-to-ground lightning and positive ground-to-ground lightning, of which the proportion of negative ground-to-ground lightning is higher, especially in plain areas. In a typical negative ground-to-ground lightning discharge, the current will quickly rise to its peak value within 1-10 microseconds, usually reaching tens of thousands of amperes, and then decay relatively slowly within a longer range of 50-200 microseconds. When the lightning current hits the turbine blades of the RAT, it will be transferred to the ground of the aircraft through the lowest impedance path of the RAT system.

[0004] Without lightning protection, this current transfer path places very stringent requirements on the design of the RAT generator. Generally speaking, when designing a RAT system, the smaller the gap between the rotor and stator of the generator, the higher the motor efficiency of the RAT system generator. However, at the same time, if the gap between the rotor and stator of the generator is designed to be too small, when the RAT system is struck by lightning, the risk of the stator and rotor being broken down by large current increases, causing the generator to be damaged by lightning.

[0005] Therefore, the RAT systems currently used on aircraft all include lightning protection mechanisms, so the design of the generator of the RAT system will be restricted by the lightning protection mechanism. For example, compared with generators without lightning protection requirements, a larger gap between the stator and the rotor needs to be considered, which affects the motor efficiency of the generator. Therefore, lightning protection requirements and generator efficiency are two mutually restrained design considerations. In the case of setting up a lightning protection mechanism, if a certain amount of power generation is to be maintained, the volume of the generator and other parameters need to be increased, making it more difficult to reduce weight during the design of the RAT generator.

[0006] Another generator with lightning protection design that can be referenced is the wind turbine. The lightning protection design of the wind turbine mainly adopts a lightning rod-type protective cover design. Among them, the lightning is guided by the lightning pole on the blade of the wind turbine, transmitted to the root of the blade, and then transmitted to the blade flange through the root of the blade, and then transmitted to the hub through the blade flange and the pitch bearing, and then transmitted to the main shaft through the main bearing, and then transmitted to the yaw bearing through the main shaft and the base, and finally introduced into the grounding grid through the tower. Therefore, the lightning protection design of the wind turbine is to use its gearbox grounding to release the large current generated by lightning.

[0007] However, due to the high-speed operation characteristics and release mechanism of the aircraft's RAT system, it is not suitable for the lightning protection design of wind turbines. Specifically, if a design similar to that of a wind turbine is used to ground the gearbox, the large current generated by lightning will inevitably flow through the generator rotor, thus affecting the design of the gap between the generator stator and rotor, and thus affecting its motor efficiency.

[0008] Therefore, in the field of aircraft design, it is necessary to propose a lightning protection mechanism suitable for the characteristics of the RAT system, which can provide lightning protection capability for the RAT system and help improve the motor efficiency of the generator of the RAT system. Summary of the invention

[0009] The present application is made to solve the problems existing in the prior art mentioned above. The purpose of the present application is to provide an air ram turbine (RAT) system with an improved structure, which can reduce the risk of damage to the generator by lightning strikes and help improve the motor efficiency of the generator of the ram air turbine system.

[0010] The present application provides a ram air turbine system, which is applied to an aircraft and includes: a turbine, the turbine including a turbine housing, a gearbox contained in the turbine housing; a generator, the generator connected to the gearbox; and a turbine blade, the turbine blade being able to rotate about a rotation axis and connected to the gearbox, so that the rotational motion of the turbine blade can be transmitted to the generator via the gearbox. A blade insulator is provided at the connection portion between the turbine blade and the turbine housing, and the blade insulator is made of an insulating material. In addition, a high-resistance bushing is provided at or near the portion of the turbine blade connected to the gearbox, and the high-resistance bushing is made of a high-resistance material.

[0011] In the ram air turbine system described above, by providing blade insulation at the connection between the turbine blade and the turbine casing, and providing a high resistance bushing at the connection between the turbine blade and the gearbox, the gearbox is not on the optimal conductive path. Thus, after the ram air turbine system is struck by lightning, the conductive path will mainly flow along the surface of the turbine blade and the turbine casing, which is usually made of metal, and will not or will hardly flow to the generator. Therefore, the gap between the rotor and the stator of the generator can be set to a suitable range to improve the efficiency of the generator, thereby helping to reduce the overall weight of the ram air turbine.

[0012] Preferably, the gearbox is also made of high-resistance material. In this way, the current flowing through the gearbox can be further attenuated to more effectively prevent the current from flowing to the generator.

[0013] Among them, high-resistance materials include insulating materials and high-resistance alloy materials. Specifically, the middle part of the corresponding component is made of insulating material, and at least the contact parts between the components that are easily worn are made of high-resistance alloy materials. In this way, while meeting the requirements of lightning protection, the wear resistance requirements of the components can also be met.

[0014] Preferably, the ram air turbine system further comprises a grounding wire connected between the turbine casing and the aircraft frame of the aircraft to guide the current of the lightning strike to the aircraft frame. In this way, the current can be grounded via the aircraft frame.

[0015] Preferably, the grounding wire is connected to the part of the turbine housing that is located on the side of the generator near the gearbox and is spaced a distance from the generator. By this arrangement position of the grounding wire, the current can be directed to the aircraft frame before the current arrives at the generator.

[0016] Preferably, a generator insulation belt is provided at one end of the generator close to the gearbox. The provision of the turbine inner insulation layer helps to further isolate the generator from lightning current.

[0017] Preferably, a turbine inner insulation layer is provided on the inner side surface of the turbine housing, and the turbine inner insulation layer is made of an insulating material. Providing the turbine inner insulation layer helps to further limit the conductive path to the outer surface of the turbine housing.

[0018] In one exemplary configuration, a turbine blade includes a pitch control mechanism extending from a turbine casing to a gearbox and pivotably connected to the gearbox.

[0019] Specifically, the pitch control mechanism includes: a pitch control spring; a pitch control mechanism base, which is connected to the pitch control spring and biased in an initial position by the pitch control spring, wherein the pitch control mechanism base can pivot around a connection point between the pitch control mechanism base and the pitch control spring; and a centrifugal member, which is arranged on the pitch control mechanism base and can provide centrifugal force as the turbine blades rotate.

[0020] Preferably, a gap is formed at the connection position between the pitch adjustment mechanism and the gearbox. The setting of the gap can provide space for the pivoting of the pitch adjustment mechanism on the one hand, and can increase the resistance between the pitch adjustment mechanism and the gearbox on the other hand, which helps to further reduce the current flowing through the gearbox. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The preferred embodiments of the present invention are shown in the accompanying drawings, from which the specific implementation of the present invention can be more clearly understood, wherein:

[0022] Figure 1 A schematic structural diagram of the ram air turbine of the present application is shown, wherein the turbine blades are in a state before pitch adjustment.

[0023] Figure 2 Another structural diagram of the ram air turbine of the present application is shown, in which the current conducting path when struck by lightning is illustrated.

[0024] Figure 3 The ram air turbine of the present application is shown Figure 1 A similar schematic diagram showing the turbine blades in a pitch-adjusted position.

[0025] (Explanation of symbols)

[0026] 1 Ram Air Turbine System

[0027] 2 Aircraft racks

[0028] 3. Generator

[0029] 11 Turbine Blades

[0030] 12 Gap

[0031] 20 Turbines

[0032] 21 Turbine casing

[0033] 22 Grounding wire

[0034] 31 Blade insulation

[0035] 32 Gearbox

[0036] 33 High resistance bushing

[0037] 34 Generator insulation tape

[0038] 35 Turbine inner insulation layer

[0039] 40 propeller adjustment mechanism

[0040] 41 Pitch spring

[0041] 42 Propeller mechanism base

[0042] 43 centrifugal parts

[0043] X rotation axis

[0044] P conductive path DETAILED DESCRIPTION

[0045] The specific implementation methods of the present application will be described in detail below in conjunction with the accompanying drawings. It should be understood that what is shown in the accompanying drawings is only a preferred embodiment of the present application, which does not constitute a limitation on the scope of the present application. Those skilled in the art can make various obvious modifications, variations, and equivalent substitutions to the present application based on the embodiments shown in the accompanying drawings, and under the premise of no contradiction, the technical features in the different embodiments described below can be arbitrarily combined with each other, which all fall within the scope of protection of the present application.

[0046] Figure 1 FIG. 1 is a schematic diagram showing an exemplary structure of a ram air turbine system 1 of the present application. The ram air turbine system 1 includes a turbine 20 having a turbine housing 21, in which a gearbox 32, a generator 3 (see FIG. 1 ) and a turbine housing 21 are housed. Figure 2 ) and other components. The turbine housing 21 can be made of conductive materials such as metal.

[0047] The ram air turbine system 1 further includes a plurality of turbine blades 11. For example, the ram air turbine system 1 shown in the figure includes two turbine blades 11, which are arranged along the circumferential outer surface of the turbine housing 21. Preferably, the two turbine blades 11 are arranged 180° apart from each other along the circumference of the turbine housing 21. The turbine blades 11 extend into the turbine 20 and are connected to the gearbox 32. The turbine blades 11 can rotate about the rotation axis X, and the rotation of the turbine blades 11 can transmit the rotational motion to the generator 3 ( Figure 2 ), specifically transmitted to the rotor of the generator 3, thereby driving the generator 3 to generate electricity. Here, the rotation axis X of the turbine blades 11 is preferably substantially coincident with the longitudinal axis of the turbine 20.

[0048] A blade insulation member 31 is provided at a connection portion between the turbine blade 11 and the turbine housing 21 of the turbine 20. The blade insulation member 31 is made of an insulating material, such as polytetrafluoroethylene, quartz glass, ceramics, silicon, etc. When the ram air turbine system 1 is released into the air flow and struck by lightning, the blade insulation member 31 can prevent the current of the lightning from flowing along the turbine blade 11 through the turbine housing 21 to the gearbox 32 inside the turbine 20, or at least can significantly reduce the current flowing into the gearbox 32.

[0049] Further, in Figure 1 It is shown exemplarily that a high-resistance bushing 33 is provided at or near the connection between the turbine blade 11 and the gearbox 32 of the turbine 20. The high-resistance bushing 33 can further block or weaken the current flowing into the gearbox 32. The high-resistance bushing 33 is made of a high-resistance material, so that while achieving lightning protection, it can also meet the wear resistance requirements at the connection between the turbine blade 11 and the gearbox 32. Specifically, the high-resistance material is mainly made of insulating material, and at least at the contact position between the turbine blade 11 and the gearbox 32 that is prone to wear, a high-resistance alloy material is used, such as a chromium-iron-aluminum alloy, a nickel-chromium-iron alloy, etc. with high resistance.

[0050] Preferably, each component of the gearbox 32, such as the gears therein, is also made of the high-resistance material described above. In this way, when struck by lightning, the current flowing through the gearbox 32 can be further attenuated. In this way, almost no current will reach the generator 3 connected to the gearbox 32. In this way, when designing the generator 3, the gap between the stator and the rotor of the generator 3 can be designed to a suitable value without considering the lightning protection requirements of the generator 3, thereby effectively improving the motor efficiency of the generator 3.

[0051] Through simulation and testing, it is estimated that the ram air turbine system 1 with the above structure can improve the motor efficiency of the generator 3 by 6-10% (from about 80-84% to 90% or more). The improvement of the motor efficiency of the generator 3 and the reduction of the corresponding lightning protection components can reduce the overall size and weight of the ram air turbine system 1 by 4-6%. For example, a conventional type of ram air turbine system 1 has a total weight of about 75 kg, and according to the above ratio, it can reduce the weight by 3 kg or more.

[0052] Go to Figure 2, which shows that a grounding wire 22 is connected between a turbine housing 21 of a turbine 20 and an aircraft frame 2, for guiding the lightning current to the aircraft frame 2, so that the lightning current can be grounded through the aircraft frame 2. The grounding wire 22 is preferably connected to a side of the generator 3 of the turbine 20 close to the gearbox 32, in particular, at a position on the turbine 20 that is spaced apart from the generator 3 toward the gearbox 32. In this way, the current is guided to the aircraft frame 2 by the grounding wire 22 before reaching the generator 3.

[0053] In the present application, by providing a blade insulation member 31 at the connection portion between the turbine blade 11 and the turbine housing 21, providing a high-resistance bushing 33 at the connection portion between the turbine blade 11 and the gearbox 32, and using a high-resistance material to manufacture the high-resistance bushing 33, at least one of the following solutions is adopted, so that the gearbox 32 is not on the optimal conductive path, and the conductive path P of the ram air turbine system 1 of the present application after being struck by lightning is as follows: Figure 2 As shown by the dotted line in , it first flows along the turbine blades 11 to the outer surface of the turbine housing 21, then flows along the outer surface of the turbine housing 21, and is then guided by the grounding wire 22 to the aircraft frame 2, and then can be grounded.

[0054] Preferably, if Figure 2 As shown, a generator insulating strip 34 is preferably provided at one end (front end) of the generator 3 close to the gearbox 32 to further prevent current from flowing into the generator 3 .

[0055] More preferably, a turbine inner insulating layer 35 made of insulating material is provided on the inner surface of the turbine housing 21. The turbine inner insulating layer 35 can ensure that the lightning current flows along the conductive path P on the outer surface of the turbine housing 21, thereby preventing or significantly reducing the current flowing into the turbine 20.

[0056] Back to Figure 1 Optionally, the turbine blade 11 of the ram air turbine system 1 may further include a pitch adjustment mechanism 40, which may be, for example, a portion of the turbine blade 11 extending from the turbine housing 21 to the gearbox 32 as shown in the figure. As shown in the figure, the pitch adjustment mechanism 40 includes a pitch adjustment spring 41 and a pitch adjustment mechanism base 42, the pitch adjustment mechanism base 42 is connected to the pitch adjustment spring 41, and is biased in its initial position under the action of the pitch adjustment spring 41, the initial position is, for example, Figure 1 The turbine blades 11 are shown in a position where the pitch angle is approximately 10°.

[0057] A centrifugal component 43 is disposed on the pitch control mechanism base 42 , and when the turbine blades 11 rotate around the rotation axis X, the centrifugal component 43 can provide centrifugal force.

[0058] When the ram air turbine system 1 is released into the airflow, under the combined force of the wind force of the airflow and the centrifugal force provided by the centrifugal member 43, the pitch adjustment mechanism base 42 can pivot around the connection point between the pitch adjustment mechanism base 42 and the pitch adjustment spring 41 to overcome the elastic force of the pitch adjustment spring 41 until the combined force of the wind force and the centrifugal force is balanced with the elastic force of the pitch adjustment spring 41, for example Figure 3 The turbine blades 11 shown in FIG. 1 have a pitch angle of approximately 67°.

[0059] like Figure 3 As shown, a gap 12 is formed at the connection position between the pitch mechanism 40 and the gearbox 32. On the one hand, the gap 12 can provide space for the pivoting movement of the pitch mechanism base 42, and on the other hand, the gap 12 can also increase the resistance between the pitch mechanism base 42 and the gearbox 32, thereby preventing or significantly weakening the current flowing from the pitch mechanism base 42 to the gearbox 32.

[0060] The above describes the exemplary preferred structure of the present application, however, the disclosed structure is not intended to limit the scope of the present application. Those skilled in the art can make various obvious modifications and variations to the present application based on the disclosed structure, which are also within the scope of the present application.

Claims

1. A ram air turbine system, the ram air turbine system being applied to an aircraft and comprising: a turbine including a turbine housing containing a gearbox; a generator connected to the gearbox; as well as a turbine blade, the turbine blade being rotatable about a rotation axis and being connected to the gearbox so that the rotational movement of the turbine blade can be transmitted to the generator via the gearbox; The invention is characterized in that a blade insulation member is provided at a connection portion between the turbine blade and the turbine housing, and the blade insulation member is made of an insulating material; and A high-resistance bushing is arranged at a portion of the turbine blade connected to or near the gearbox, and the high-resistance bushing is made of a high-resistance material.

2. The ram air turbine system of claim 1, wherein: The gearbox is made of high-resistance material.

3. The ram air turbine system according to claim 1 or 2, characterized in that: The high resistance material includes insulating material and high resistance alloy material.

4. The ram air turbine system of claim 1, wherein: The ram air turbine system also includes a ground line connected between the turbine casing and an airframe of the aircraft.

5. The ram air turbine system of claim 4, wherein: The grounding wire is connected to a portion of the turbine housing located on a side of the generator close to the gearbox and is spaced apart from the generator by a distance.

6. The ram air turbine system of claim 1, wherein: A generator insulation belt is arranged at one end of the generator close to the gearbox.

7. The ram air turbine system of claim 1, wherein: A turbine inner insulation layer is arranged on the inner side surface of the turbine housing, and the turbine inner insulation layer is made of an insulation material.

8. The ram air turbine system of claim 1, wherein: The turbine blade includes a pitch adjustment mechanism extending from the turbine housing to the gearbox and pivotably connected to the gearbox.

9. The ram air turbine system of claim 8, wherein: The pitch adjustment mechanism comprises: Pitch spring; a pitch adjustment mechanism base, the pitch adjustment mechanism base being connected to the pitch adjustment spring and being biased in an initial position by the pitch adjustment spring, wherein the pitch adjustment mechanism base is capable of pivoting around a connection point between the pitch adjustment mechanism base and the pitch adjustment spring; and A centrifugal component is arranged on the base of the pitch adjustment mechanism and can provide centrifugal force as the turbine blades rotate.

10. The ram air turbine system according to claim 8 or 9, characterized in that A gap is formed at a connection position between the pitch control mechanism and the gearbox.

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