DE1960005B

DE1960005B - Suspension of an engine on an aircraft

Info

Publication number: DE1960005B
Application number: DE19691960005
Authority: DE
Original assignee: Vereinigte Flugtechnische Werke Fokker 2800 Bremen GmbH
Current assignee: Vereinigte Flugtechnische Werke Fokker 2800 Bremen GmbH
Filing date: 1969-11-29
Publication date: 1972-05-18

Description

sentlichen an zwei Stellen, die durch die Mittellinien S₁ 6 gekennzeichnet sind, an dem Pylon 3 aufgehängt. Letzterer ist mit der Struktur des Flügels 2 fest verbunden. Die erfindungsgemäße Ausführung sieht nun an der Lageratelle 6 ein elastisches Glied 7 vor, das als elastischer Stab ausgebildet ist, Wie aus der Darstellung ersichtlich, ist der elastische Stab annähernd parallel zur Triebwerksachse 4 angeordnet. An seinen beiden äußeren Enden stützt er sich über eine Gabel an dem Pylon 3 ab, während in der Mitte des elastischen Stabes ein Arm angreift, der mit dem Triebwerk 1 verbunden ist.sentlichen at two points, which are marked by the center lines S ₁ 6, suspended from the pylon 3. The latter is firmly connected to the structure of the wing 2. The embodiment according to the invention now provides an elastic member 7 on the bearing element 6, which is designed as an elastic rod. As can be seen from the illustration, the elastic rod is arranged approximately parallel to the engine axis 4. At its two outer ends it is supported by a fork on the pylon 3, while an arm connected to the engine 1 engages in the middle of the elastic rod.

Die Wirkung der erfindungsgemäßen Anordnung des elastischen Gliedes 7 ist schematisch in F i g. 3 dargestellt. Diese zeigt eine Ansicht von oben auf das Triebwerk 1, d. h. die dargestellte Skizze liegt in der x-y-Ebene. Bei dieser Anordnung des Triebwerkes 1 auf dem Flügel 2 liegt ein mechanisches Schwingungssystem vor, das durch die Massen von Triebwerk 1 und Tragwerk 2 sowie die Federsteifigkeiten von Abstandhalter 3 und Tragwerk 2 gekennzeichnet ist. Wird beispielsweise die Spitze des Flügels 2 durch eine Bö zu Biegeschwingungen angeregt, so übertragen sich diese Bewegungen über den Abstandhalter 3, der in dem mechanischen Ersatzsystem als massenlose Feder anzusehen ist, auf das Triebwerk 1. Dieses führt dann Schwingungen vorwiegend in y-Richtung aus, Durch die erfindungsgernöße Zwischenschaltung des elastischen Gliedes 7 zwischen Triebwerk 1 und Abstandhalter 3 wird die resultierende Federsteifjgkeit des Abstandhalters 3 verringert, d, h, das ganzeThe effect of the arrangement according to the invention of the elastic member 7 is shown schematically in FIG. 3 shown. This shows a view from above of the engine 1, i. H. the sketch shown is in the x-y plane. With this arrangement of the engine 1 on the wing 2 there is a mechanical vibration system before that by the masses of engine 1 and structure 2 as well as the spring stiffnesses is marked by spacer 3 and structure 2. For example, the tip of the wing 2 is through If a gust is excited to flexural vibrations, these movements are transmitted via the spacer 3, which is to be regarded as a massless spring in the mechanical equivalent system, on the engine 1. This then carries out vibrations predominantly in the y-direction, due to the interposition of the invention of the elastic member 7 between engine 1 and spacer 3 is the resulting spring stiffness of the spacer 3 is reduced, that is, the whole

Schwingungssystem wird weicher. Da das Triebwerk 1 an seiner vorderen Aufhängung S drehbar gelagert ist, werden Pendelbewegungen des Triebwerks, die durch den elastischen Stab kontrolliert werden, um die Achse 5 ermöglicht; das Triebwerk 1 kannThe vibration system becomes softer. Since the engine 1 is rotatably mounted on its front suspension S pendulum movements of the engine, which are controlled by the elastic rod, allows about the axis 5; the engine 1 can

ίο dabei aus der Ruhelage, dargestellt durch die Mittellinie 4, in die Stellungen ausgelenkt werden, wie sie durch die Mittellinien 4' und 4" gekennzeichnet sind.ίο from the rest position, represented by the center line 4, are deflected into the positions as indicated by the center lines 4 'and 4 " are.

Auf diese Art und Weise wird das ganze Schwin-In this way, the whole

gungssystem durch Zwischenschaltung einer zusätzlichen Federsteifigkeit verstimmt. Es tritt keine Resonanz zwischen Triebwc■/*, 1 und Tragwerk 2 auf, und unzulässig hohe mechanische Beanspruchungen von Konstruktionsbauteilen werden vermieden.system by interposing an additional Spring stiffness out of tune. There is no resonance between engine ■ / *, 1 and structure 2, and Inadmissibly high mechanical loads on structural components are avoided.

ao Die erfindungsgemäße Ausführung des elastischen Gliedes als elastischen Stab bietet schließlich noch folgende Vorteile, besonders Lm Vergleich zu Elastomeren: rlas elastische Glied ist gegen thermische Beanspruchung wenig empfindlich; der elastische Stabao The embodiment according to the invention of the elastic member as an elastic rod finally still offers the following advantages, especially compared to elastomers: The elastic member is against thermal stress not very sensitive; the elastic rod

baut klein und erfüllt daher die strengen Forderungen der Raumbeschränkung, die aus der aerodynamischen Formgebung des Abstandhalten resultieren.builds small and therefore fulfills the strict requirements of the space restriction resulting from the aerodynamic Shaping the spacing result.

Hierzu 1 Blatt Zeichnungen1 sheet of drawings

Claims

1 21 2

members) are not very suitable in aircraft construction.

Claim: net, vibrations with frequencies below the

Avoid sound range; because these frequencies

Suspension of an engine on an air in the infrasound range requires greater spring travel, vehicle in two places, the engine at 5, which requires more one of the two points to pivot around an axis for the structural design of the springs, volume and thus more weight. Is stored outside, characterized by the fact that the connection at the second point is high temperatures in the vicinity of the engine (1) leave parallel to the pivot axis of the ion. Finally, the service life of the engine (1) is at the first connection point rubber or similar materials in relation to their extends and its end with the mean elasticity and strength is relatively low,
The invention is based on the object of avoiding the position between the engine and the airframe at right angles to the above-mentioned swivel axis and the ends of which are held by a fork 15 the associated inadmissibly high mechanics that are attached to the airframe ( 2) see stresses on the structural component attached. "to the permissible limit. According to the invention, this is done by the fact that the connection at the second point from one of the engine

20 existing arm, which is parallel to the pivot axis of the engine at the first connection point extends and the end of which is firmly connected to the central region of an elastic rod,

The invention relates to a suspension which is perpendicular to said pivot axis of an engine on an aircraft at two locations and the ends of which are held by a fork, the engine at one of the two locations being attached to the airframe.
^r a Oh e is pivotally mounted. As is well known, resonance phenomena can be found in the attachment of engines to a mechanical vibration system whose aircraft are ej several embodiments, natural frequencies through masses and spring stiffness of which the arrangement of the engines on the wing 30th are determined by the change last and the tail are most common. Avoid the rer sizes. But since in aircraft construction an engine is attached to the airframe with the help of a spacer (pylon, change in mass (engine and airframe) or © the engine shaft). As a result of the spring stiffness (spacer and, for example, simple spring stiffness of the spacer and the stiffness of the wing) due to existing ae-ZcIIe and due to the masses of the engine and the dynamic and structural requirements of the cell, vibrations between the engine and possible odei is advantageous, will occur from this type of cell or cell components. In the unfavorable-disgruntlement not made use of. In this respect, the best case scenario is that the engine and airframe, e.g. B. which indicates the insertion of an elasti-wing according to the invention, in resonance; As is well known, rods have a particular advantage: The masses are subject to high stresses. In these cases, or weights do not need to be changed, appropriate measures must be tried, and the existing spring stiffness, ie the vibrations in the resonance range and thus the incomplete cell tone structure, are retained. In addition, an advantage that can be overridden by high mechanical stresses is that they occur. elastic rod according to the invention, if required, in a simple manner In aircraft construction, means are known which can be exchanged in a resonant manner, ie the spring impact between the engine and the airframe and the lower stiffness of the spacer can be adjusted. Should bind. In these designs, as shown in German, for example: the aircraft is equipped with a more powerful engine, ie a heavier engine, that is, the German patent specification 901260, this measure would involve changes in the dimensions It is about the elastic mounting of the cell construction, ie also of the spring drives with respect to the cell construction stiffness. condition. To meet these demands. The fillers specially used for this purpose are needed in the suspension device according to the invention, and only the elastic rod is removed from the engine under the name "Schwingmetalle" (Schwingmetalle). An elastomer is provided as the elastic force transmission medium and is exchanged for another document mentioned in relation to the sections mentioned.

that, spoken in the vibrational sense, so- An embodiment of the invention is in the

probably acts as a spring as well as a damping. These EIe drawings are shown and will be explained in more detail below

elements are excellently suited, vibrations are described as higher.

Absorb frequency (sound range); The perspective of the structure-borne sound and vibrations is therefore mostly based on the structure-borne noise. In this embodiment, the engine 1 is fastened to vibrations from the cell by means of a spacer 3 (also called a pylon or drive. To this extent, it is a factory stick) attached to the wing 2. Means to avoid resonance, namely the point between the engine 1 and spacer 3 by utilizing the elastic and damping 65 marked black denotes the location properties of rubber or similar material of the elastic member according to the invention,
fen. F ί g. 2 shows a side view of the engine-such means (elastomeric spring and damping fastening on the wing, the engine 1 is in the w