DE102015110701A1 - Device for isolating rotor vibrations in an aircraft engine - Google Patents

Abstract

In order to isolate rotor vibrations in an aircraft engine (100) which has a rotor mounted in an engine casing (101), a device is proposed which has at least one actuator (122) which, depending on electrical signals, has mechanical forces (fp). to counteract vibrations that occur due to the rotor vibrations in the aircraft engine, wherein the respective actuator (122) in a cavity (121) of an aircraft engine component (130) is integrated, by means of a core engine housing (104) of the aircraft engine (100 ) is attached to the engine casing (101) or a portion (150) thereof. Preferably, the aircraft engine component is an at least partially hollow strut (122) which connects the core engine housing (104) to the engine compartment (150) portion (150), wherein the portion preferably forms an intermediate housing (150) which defines the core engine housing (104 ) coaxially in the longitudinal direction of the aircraft engine (100) encloses. The brace (130) is preferably arranged in a front section (110) of the aircraft engine (100), in particular in the region of a front attachment structure (111) of the aircraft engine (100).

Description

The invention relates to an apparatus for the isolation of rotor vibrations in an aircraft engine according to the preamble of claim 1. Furthermore, the invention relates to an aircraft engine, which is equipped with such a device for the isolation of rotor vibrations.

Worldwide air traffic is forecast to increase by about 5% to 7% per year. At the same time, the demands placed on aircraft engines are constantly increasing. This applies in particular to fuel consumption and exhaust and noise emissions. The latter aspect of the perceptible noise and the associated perceptible vibrations resulting due to a low structural damping significantly from the oscillations generated in the aircraft engine during operation, in particular vibrations, which go back to the rotor vibrations of the aircraft engine.

For example, due to fluid-structure interactions in the narrow gap between Schaufelradende and turbine housing or especially by imbalance excitation to the vibration of the engine shaft or the rotor. In order to reduce these vibrations, passive elements, so-called squeeze-film damper (SFD) are often used successfully in practice. The advantages include high reliability and good system attenuation in the designed frequency range. Significant disadvantages are the need for a cumbersome oil supply and the fact that the interpretation of such a system damping due to complex nonlinearities is significantly experiential based. It should be noted that during a typical flight cycle of a passenger aircraft, various operating points are approached transiently when starting or landing or when adjusting the cruising speed and altitude, resulting in a system excitation in a wide frequency range. Without suitable damping measures, it is possible in some cases for very strong, comfort-impairing oscillation amplitudes. However, passive damping or SFD only works optimally in a certain frequency range and is therefore not suitable for effectively reducing rotor vibrations in the entire operating frequency range.

In order to meet increasing ambitions with respect to vibration reduction and comfort increase, it is known to use actuators which are designed to generate mechanical forces depending on electrical signals, which counteract occurring rotor vibrations or the vibrations generated thereby. Piezoactuators, in particular piezoelectric stack actuators, are often used for this purpose, because of their widespread material composition, which frequently consists of plumbum zirconate titanate, also sometimes referred to as PZT actuators, which are essentially composed of a stack of ceramic discs, so that the total extension of the PZT actuator is composed of the sum of the individual expansions of the ceramic discs. In addition to its high rigidity, the PZT actuator is characterized by its high power density coupled with high dynamics. With the aid of a suitable sensor and a control algorithm, a closed mechatronic control circuit can be set up, which makes it possible to actively influence the vibrations of an aircraft engine in a wide frequency range or to isolate as far as possible the rotor vibrations from the components surrounding the rotor, such as the engine casing and suspension, to achieve.

In the patent US 8, 702, 377 B2 (see there 1 . 2 & 5 ) discloses an apparatus for isolating rotor vibrations in an aircraft engine having a rotor mounted in an engine case 122, the apparatus having at least one actuator (actuator 502), depending on electrical Signals to generate mechanical forces (see there text, column 6, lines 1-42). The actuator there acts together with a so-called "vibration isolator 150" on the bearing of the rotor (bearing assembly 202 "in 3 ) and thus achieves an active rotor bearing, which counteracts in particular the occurring due to imbalances rotor vibrations. Although such active bearing of the rotor can reduce the total vibrations; However, the installation of an actuator in the storage area is extremely difficult due to the extremely limited space.

From the DE 101 54 391 A1 is the use of piezoelectric strain actuators known for reducing vibrations or vibrations that may occur in helicopters in the main gearbox. A reference to aircraft engines in the strict sense, however, is not produced.

The object of the invention is to effectively isolate rotor vibrations occurring in an aircraft engine from the environmental structure and to significantly improve known approaches to this end. In particular, as an alternative or in addition to a known active rotor bearing by using one or more actuators in the aircraft engine further occurring vibrations should be effectively counteracted.

The object is achieved by a device having the features of claim 1 and by a thus equipped aircraft engine according to the independent claim.

Accordingly, an apparatus for the isolation of rotor vibrations in an aircraft engine is proposed, which has at least one actuator which is adapted to generate mechanical forces depending on electrical signals to counteract vibrations that occur due to the rotor vibrations in the aircraft engine, wherein the respective actuator in a cavity of an aircraft engine component is integrated, by means of a core engine housing of the aircraft engine is attached to a portion of the engine housing.

Preferably, the respective actuator is integrated into an aircraft engine component, which is designed as an at least partially hollow-shaped brace, which connects the core engine housing with the portion of the engine housing. The subregion is preferably formed as an intermediate casing (English: "intermediate casing", short IMC), which encloses the core engine casing coaxially in the longitudinal direction of the aircraft engine. The strut with the actuator integrated therein is preferably arranged in a front section of the aircraft engine, in particular in the region of a front attachment structure for suspending the aircraft engine. The respective actuator should preferably be mounted in close proximity to the suspension points of the aircraft engine.

The invention thus provides a device for isolating rotor vibrations in an aircraft engine, which is preferably realized in an intermediate housing, wherein the device has at least one actuator which is adapted to generate mechanical forces depending on electrical signals to the transmission of vibrations occurring to counteract the environment structure. The device is distinguished by the fact that the respective actuator is integrated in a cavity of an aircraft engine component, by means of which an attachment of the aircraft engine to the aircraft structure takes place via suspension points.

Thus, a space-saving, very efficient solution is created by the present invention, with which a construction called "active suspension" can be realized, in which an actuator is integrated on the engine side directly below the suspension points of the engine. Irrespective of the source of the vibration, the design has been found to provide significant vibration isolation between the engine and aircraft fuselage, thereby providing comfort enhancement in the aircraft cabin. For constructive feasibility, a rather small amount of modification is required, e.g. on the engine braces of the intermediate housing. Since the actuators can be connected in parallel in the power flow generated by the engine and guided by the braces, this concept can be classified as very safe even in the event of a total failure of the actuators.

The invention also relates to a new aircraft engine, which is equipped with such a device for the isolation of rotor vibrations and thus achieved in its overall construction a fully integrated active vibration isolation.

Further preferred embodiments emerge from the subclaims.

Accordingly, actuators preferably piezo actuators, in particular piezoelectric stack actuators, are used, which can be very well integrated into existing hollow space struts and the like due to their elongated, relatively slim, design.

Optionally, each actuator may have an internal channel with an entrance and exit suitable for passing a cooling medium, such as e.g. a in the engine anyway guided air flow (cooling outside air), is provided.

Preferably, the respective actuator in the cavity of such an aircraft engine component, in particular a strut, integrated, which has a support structure or stiffening, which limits the cavity to match the size of the actuator. The actuator is thus completely built into the cavity and can actively influence the dynamic stiffness of the suspension via the support structure directly.

In addition to an "active suspension" in the front region of the aircraft engine, at least one further actuator device for "active suspension" can also be arranged in the rear section of the aircraft engine. The invention is thus directed to constructions which can each cause an effective "active suspension" of the engine in the front and / or rear of the aircraft engine. Overall, a more comprehensive vibration isolation for particularly high comfort requirements can be achieved by the invention. Therefore, a costly "active rotor bearing" is unnecessary in many applications.

The invention and the resulting advantages will be described below in more detail with reference to embodiments, with reference to the accompanying drawings Reference is made to reproduce the following schematic representations:

1 shows in longitudinal section the structure of an aircraft engine;

2 shows the construction of a housing portion, here for example the intermediate housing, of an aircraft engine in cross section;

3 shows in cross section the structure of a conventional brace in the region of the intermediate housing of the aircraft engine;

4 shows in cross section the structure of a strut according to the invention with integrated actuator; and

5 shows in cross section the rear portion of the aircraft engine with there additionally attached actuators.

Based on 1 and 2 First, the general structure of an aircraft engine according to the invention 100 described. The aircraft engine is in an engine housing 101 accommodated, which may be constructed in one piece or in several parts, and is about a mounting structure with suspension or attachment points 111 in the front area 110 mounted on the aircraft. In this example, we assume a three-piece engine case: the front section 110 of the aircraft engine includes, inter alia, the fan and the high pressure compressor. The rear area or section 120 essentially comprises the combustion chamber, the high-pressure turbine and the low-pressure turbine. In the middle part of the in 1 shown engine is a portion of the engine housing with " 150 " designated. This subarea 150 represents the so-called. Intermediate housing, which several struts 130 having, for fastening the core engine housing 104 serve. In particular, the present invention relates to integration of one or more actuators in individual struts and will be described in detail below as "active suspension" (see also FIG 4 ).

Regarding the rotor bearing of the engine shown here 100 Optionally, the known "active storage" can be used. However, this is dispensable in many cases due to the high effectiveness of the present invention ("active suspension").

What the rear area 120 As far as the engine is concerned, according to the invention actuators for "active suspension" can also be used there. This is in 1 by the suspension 103 and the pursuit 170 and will also be described in detail below (see also 5 ).

First, an inventive "active suspension" in the front region of the engine, namely in the region of the intermediate housing 150 , described:
Usually located in the area of the intermediate housing 150 several struts 130 (English "struts"), one of them in their conventional structure in the 3 is shown. The struts are used to attach the core housing 104 in the engine and extend in the radial direction so that they form a star-shaped bracing structure (see also 2 ). A single strut runs for example from the bearing shell (so-called "bearing shell") 112 to the core housing (so-called "core engine") 104 and then on to the intermediate housing or IMC 150 which part of the engine housing 101 is. Usually, as in 3 shown, single struts 130 ' tubular, so that, for example, electrical or hydraulic lines and mechanical functional parts (transmission shafts or the like) can be performed through the respective struts. Each conventional brace usually has only a single cavity, which is often used for the passage of electrical or hydraulic lines, which are the engine components inside the core housing 104 connect to units located outside the engine case (see also 2 ).

As the 1 . 2 and 4 show are in the range of the front suspensions 111 at least in some of the tubular struts 130 now according to the invention actuators 122 integrated to actively counteract the transmission of vibrations through the bracing structure from the rotor or core housing to the suspensions 111 be transmitted.

The present invention effectively addresses the problem that the vibration level of an engine has a direct impact on the vibrations and thus comfort in the aircraft cabin. In the civilian field of application of engines, the comfort problem plays a much greater role than in military applications. The engine described here is intended to be used in particular in the comfort-sensitive luxury segment. It can e.g. be designed as a two-shaft engine with a fivefold storage.

The invention is based on the knowledge known per se, that as a significant cause of the vibrations emanating from the engine, the unbalanced vibrations are to be mentioned on the rotors, which on the rotor bearing the entire engine and the engine suspension (see suspension points 111 in 1 ) also stimulate the aircraft cabin to vibrate. During the production process of the aircraft engine, it is attempted to realize the rotor bearing as free as possible of imbalances. However, later in the assembled state or in operation, a residual residual imbalance often occurs, which causes noticeable loss of comfort, even if it has no safety-relevant significance.

Regarding the residual imbalance, it can indeed be rebalanced in a two-shaft engine using the so-called "trim balancing" on the low-pressure wave on the easily accessible fan. However, the high-pressure shaft is difficult or impossible to access for a subsequent balancing process for structural reasons. Thus, with the aid of the present invention, in particular the unbalanced vibrations emanating from the high-pressure shaft can be minimized by the device presented here. Investigations of the solution presented here have revealed that the invention can be incorporated into existing aircraft engine components, such as those described in US Pat. hollow struts, can be fully integrated and yet, in particular the dynamic radial engine forces effectively isolated from the fuselage.

Based on 1 . 2 and 4 the structure and operation of the device for the isolation of rotor vibrations are now described in more detail:
The device according to the invention is in the respective strut 130 Fully integrated by the strut with a support structure 123 is provided so that in the area near the suspension 111 a cavity 121 for receiving an actuator 122 formed. In the here in 4 example shown is an actuator 122 completely integrated in the cavity 121 built-in. The actor 122 is realized here as a piezoelectric stack actuator and is driven by a (not shown) electronics. Furthermore, the actuator 122 even have some peculiarities, such as an encapsulation that protects the piezo stack. Also, the actuator may include a longitudinally extending channel through which a coolant (air or special coolant) is routed inside.

As the 4 shows is the actor 122 in the bracing 130 used in the longitudinal direction and is located in the upper cavity 121 right near the engine mount 111 , The in the bracing 130 Provided support structure or stiffening 123 allows a suitable fully integrated installation of the actuator 122 as well as an optimal power flow. To generate a vibration-reducing effect, the actuator becomes 122 so controlled that the resulting actuator force fp acts with opposite signs on the order of fl (see double arrow in 4 ). As a result, a pair of forces and thus a local deformation is generated, which can effectively isolate the dynamic engine forces from the fuselage with the help of a suitably designed controller.

In the front engine area, therefore, the cavities of individual struts from the intermediate housing (IMC) are occupied by cylindrical piezostack actuators. The struts directly below the connection points 111 (S. 2 ) are generally not occupied, ie have free cavities (s 3 ). Thus, the resulting strain significantly in the area of the connection point 111 acts, is as high as possible stiffening 123 at the "lower" piezo bonding surface advantageous (s. 4 ).

The actuators used here are preferably piezo stack actuators, whose construction consists essentially of a stack of ceramic discs, so that the total elongation of the actuator is composed of the sum of the individual expansions of the ceramic discs. Optionally, the piezo stack can be provided with a housing for protection against environmental influences (encapsulation). The housing can also be used to mechanically bias the actuator with the help of disc springs, so that operation in the train area is possible. Alternatively, a bias for dynamic operation could be realized via the mechanical structure to which the actuator is coupled. The mechanical separation of the ceramic discs is ensured by thin metal electrodes, which electrically connect the ceramic layers in parallel.

Piezo stack actuators are characterized by good dynamic properties paired with high achievable restoring forces in a small size. With a typical length, which may be in the range of, for example, 100-150 mm in the present example, the integration of the actuator in the strut is readily possible, whereas an actuator diameter of about 25 mm, especially for smaller engines, already at the limit of Available package diameter. For the integration of larger diameters, it is conceivable to modify the flow in the same way as the IMC's adjacent pipe-leading trutes. Furthermore, it becomes more difficult to dissipate the self-heating of the actuator core with increasing actuator diameter, because the piezoelectric material, like any ceramic, is a poor conductor of heat. One way around this problem is the use of piezostapeln with centric bore. By using a ring actuator instead of a solid actuator, one obtains a higher surface area / volume ratio, which increases the cooling capacity compared to the massivactor. Furthermore, the ring actuator with the same cost of materials better mechanical Properties on. Due to the higher outer diameter higher bending moments can be absorbed. In summary, the use of a ring actuator is recommended for high-dynamic operation.

Apart from the "active suspension" actuators installed in the front of the aircraft engine, measures can also be taken to "actively suspend" the engine at the rear.

Based on 1 and 5 Now such an "active suspension" in the rear area 120 of the engine.

As in particular on the basis of 5 It can be seen at the rear of the aircraft engine 100 other actuarial facilities 170 be used to the local suspension 131 to isolate from rotor vibrations. The installed actuators effectively prevent the vibrations that occur from the core housing 104 on the engine case 101 transfer and then over the suspension 131 to the environment structure (aircraft wings and / or
-rumpf).

For example, the actuarial devices 170 around obliquely stretched rod-shaped struts that form the core 104 with the engine case 101 connect and are provided with actuators. It is especially those pursuits 170 as close as possible to the rear connection point 131 each equipped with an electric actuator to realize an active damping or counter-force generation in the rear of the aircraft engine. This will be in the back section 120 realized an active suspension, in combination with the active suspension in the front engine area 110 ( 1 . 2 and 4 ) forms a very comprehensive overall concept. This should be unnecessary in many applications, the complex use of an "active storage" of the rotor.

As already described above, the active suspension (s. 1 . 2 . 4 and 5 ) the respective actuators 122 respectively. 170 directly under the respective front and rear suspension points 111 respectively. 131 of the engine installed. As a result, a significant vibration isolation between the engine and aircraft fuselage or wing is possible, whereby a significant increase in comfort in the aircraft cabin is achieved. Since the respective actuators are connected in parallel in the power flow generated by the engine, this concept can be classified as very safe even in the event of a total failure of the actuators.

For active suspension (front and rear) is to say that it is ultimately irrelevant from which area of the engine, the noise vibrations are caused. As long as the amplitudes and frequencies of the disturbance forces at the suspension points of the engine are covered by the power spectrum of the piezoactuator system, a vibration isolation between the aircraft and the engine is ensured. Therefore, it may be useful to implement the concept of active suspension in both the front and in the rear engine area as close as possible to the respective suspension point ..

A particular advantage of active systems is the possibility of fault diagnosis and fault monitoring during operation, which makes it possible to increase safety. In the context of the invention, the feasibility of a mechatronic system with piezo-materials based on lead zirconate titanate (PZT) for comfort increase in a real engine was analyzed and demonstrated. In the course of this, solution variants and the installation space investigations required in this connection as well as constructive implementation suggestions were developed, which allow a comfort increase. Thereby u.a. the dimensioning as well as technological challenges with regard to the piezoactuator.

For example, the entire piezo system can be applied with two actuators in the front and rear engine area, so that four actuators and power amplifiers are used. This implementation is possible with little design effort on a series engine, because the geometry and component arrangement can be largely retained. Furthermore, the system can be classified as very safe in the event of a fault or failure, because the actuators are connected in parallel to the struts in the front area and to the struts in the rear area of the engine. A functional added value can be achieved by monitoring the actuator manipulated variables in the course of an "unbalance monitoring".

In summary, the present invention provides a solution for active suspension, in particular for the front suspension in the region of the intermediate housing, by implementing the actuator system in existing cavities of those struts on an intermediate housing (IMC) which extends below the connection points are located (s. 1 ).

The actuators integrated in the front section of the engine and connected in parallel to the struts can be activated as indicated by the double arrow (s. 3a ), a pair of forces and thus generate a local deformation and with the help of a appropriately designed regulator to effectively isolate the dynamic engine forces from the fuselage. In addition, an active suspension may be provided in the aft engine area, where there are generally no hollow struts, but only flow-adapted struts. As based on the 5 has already been described, the approach according to the invention in an active strut, which is provided with eg two piezo actuators per suspension point. Thus, in each case two strut elements whose ends are fastened directly to the core housing, equipped with the actuators, as in the 5 shown to generate a pair of forces for the compensation of vibrations.

LIST OF REFERENCE NUMBERS

100

 Aircraft engine

101

 Engine Housing

150

 Intermediate Casing - IMC

104

 Core engine casing

112

 bearing shell

110

 front section / area of the engine

120

 rear section / area of the engine

111

 front attachment structure with suspension point (s)

131

 rear attachment structure with suspension point

130

 Bracing (s) [Struts] in the front area

121

 Cavity for receiving an actuator

122

 Actuator, here piezoelectric actuator

123

Support structure / stiffening

170

 Actoric device, here transverse struts with actuators, in the rear area

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• US 8702377 B2 [0005]
• DE 10154391 A1 [0006]

Claims (11)

Device for isolating rotor vibrations in an aircraft engine ( 100 ), the one in an engine casing ( 101 ), wherein the device has at least one actuator ( 122 ), characterized in that the actuator ( 122 ) is adapted to generate mechanical forces (fp) in response to electrical signals in order to counteract vibrations which occur due to the rotor vibrations in the aircraft engine, and in that the respective actuator ( 122 ) in a cavity ( 121 ) an aircraft engine component ( 130 ) by means of a core engine casing ( 104 ) of the aircraft engine ( 100 ) at a subarea ( 150 ) of the engine casing ( 101 ) is attached. Device according to claim 1, characterized in that the aircraft engine component has an at least partially hollow strut (FIG. 130 ), which is the core engine casing ( 104 ) with the subregion ( 150 ) of the engine casing ( 101 ) connects. Apparatus according to claim 1, characterized in that the aircraft engine component is an at least partially hollow-shaped strut, the bearing shell ( 112 ) with the subregion ( 150 ) of the engine casing ( 101 ) connects. Apparatus according to claim 1, 2 or 3, characterized in that the subregion of the engine housing ( 101 ) as an intermediate housing ( 150 ) which forms the core engine casing ( 104 ) coaxially in the longitudinal direction of the aircraft engine ( 100 ) encloses. Device according to one of the preceding claims, characterized in that the aircraft engine component, in particular the strut ( 130 ), in a front section ( 110 ) of the aircraft engine ( 100 ) is arranged, in particular in the region of a front attachment structure ( 111 ) of the aircraft engine ( 100 ) is arranged. Device according to one of the preceding claims, characterized in that the actuator is a piezoelectric actuator, in particular a piezoelectric stack actuator ( 122 ) is. Device according to one of the preceding claims, characterized in that the actuator is a piezoelectric actuator which is ringfömig and / or has an inner channel for passing a cooling medium. Contraption ( 1 ) according to one of the preceding claims, characterized in that the aircraft engine component, in particular the strut ( 130 ), a support structure ( 123 ) having the cavity ( 121 ) to match the size of the actuator ( 122 ) limited. Aircraft engine ( 100 ) with a device for the isolation of rotor vibrations in an aircraft engine ( 100 ), one in an engine casing ( 101 ), wherein the device has at least one actuator ( 122 ), characterized in that the actuator ( 122 ) is designed to generate mechanical forces (fp) in response to electrical signals in order to counteract vibrations that occur due to the rotor vibrations in the aircraft engine, and that the respective actuator ( 122 ) in a cavity ( 121 ) an aircraft engine component ( 130 ) is integrated by means of a core engine housing ( 104 ) of the aircraft engine ( 100 ) at a subarea ( 150 ) of the engine housing ( 101 ) is attached. Aircraft engine ( 100 ) according to claim 7, characterized in that the device is designed according to one of claims 2-6. Aircraft engine ( 100 ) according to claim 7 or 8, wherein the aircraft engine component, in particular the strut ( 130 ), in a front section ( 110 ) of the aircraft engine ( 100 ), characterized in that in addition in a rear section ( 120 ) of the aircraft engine ( 100 ) at least one actuarial device ( 170 ) is arranged to counteract vibrations occurring there.

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