DE8611677U1 - Device for controlling rotor blades - Google Patents

Description

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-1- 15.04.86

HFW2-HF

Device for controlling rotor blades

The invention relates to a device for controlling rotor blades in a helicopter, wherein
Each rotor blade can be connected to the rotor head as required
can be.

When designing helicopters, in addition to the need to save weight due to the relatively high power expenditure that must be applied per weight share, there is also the requirement for improved controllability due to the asymmetrical aerodynamics in forward flight, which leads to the typical shaking motion of the helicopter. This is linked to a further increase in performance, an increase in flight speed and an improvement in flight characteristics.

The usual control of the rotor blades is carried out with the help of a swash plate, whereby a cyclical rotor blade control is superimposed on the collective rotor blade control. This controllability is achieved by transforming the control movement of the control stick into a rotating plane and from there by passing it on to the rotor blades. The swash plate essentially consists of a rigid and a rotating ring part, whereby by tilting the fixed part of the swash plate by the pilot, the individual rotor blade assumes a constant up and down oscillating angle during rotation, the shape of which is purely sinusoidal. Due to aerodynamically caused lift disturbances on the rotor blade moving against and in the direction of flight and the vibration phenomena caused by this, this function is limited in practical operation.

The situation is similar with the spider control, where

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The swashplate built around the mast is omitted and instead a central bearing point located inside the rotor mast is used for the transmission from the rotating to the stationary system.
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If the blade pivot bearings are omitted, as is sometimes the case with modern rotor blades, the blade neck of the rotor blade is twisted to achieve the required blade pitch angle position. A torsion joint is used for this, which lies around or next to the elastic blade neck and is connected to it at the ends in a torsionally rigid manner. The torsion joint is controlled in the usual way.

If higher harmonic control movements are to take place beyond the harmonic control movement, the control rods of the fixed control system are superimposed in a suitable manner. The transmission through the rigid swash plate j into the rotating system is only possible with the vibrations

] 20 possible, which, depending on the number of rotor blades and the resulting division of a full circle, can be

j form a level. According to this, for example, the control of a

double harmonic oscillation in a 4-blade rotor

<j not possible.

25

A device for adjusting the tracking of rotor blades in a helicopter is already known from DE-PS 27 56 617, whereby each rotor blade is assigned a length-adjustable control rod with a servomotor connected to the supply unit for the rotor blade control. The adjustment of each control rod takes place during the flight by remote control from a command device in the control cabin of the helicopter via a receiver located in the supply unit for the rotor blade control on the rotating rotor head to the servomotor. Feedback of both the adjustment of the control rod via a potentiometer arranged in it and the control forces acting in the control rod

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by a measuring device installed in the control panel is shown on a display device in the driver's compartment·

The control force^ is transmitted via slip rings/ an irradiation path or by telemetry*

This known device has the advantage that the system for adjusting the blade run, which is remotely controlled from the helicopter, eliminates the need for workshop flights that were previously necessary to bring the rotor blades into line and keep the helicopter steady during flight.

From DE-OS 24 47 877 it is known to provide an arrangement of electric or hydraulic or combined servomotors for operating the rotor blade control in the rotating rotor blade in order to optimize the angle of attack of an individual rotor blade, whereby in the case of a hydraulic system the entire control force circuit including hydraulic pump, pressure relief valves, hydraulic accumulator, servo valves should also rotate in the rotor. However, how this hydraulic system, which takes up a considerable amount of space, should be accommodated in the rotor blade and how the angle of attack should be adjusted in detail cannot be found in this publication.

The object of the present invention is to provide a device for increasing rotor blades,
the single sheet control functions of any kind and/
or at the same time make changes to the blade setting,
to increase the flight speed with an improvement in the flight characteristics.
achieve.

Starting from a facility of the type described above, it is proposed to solve this problem that

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^Each rotor blade has at least one control unit which is connected to the rotor blade in such a way that its longitudinal axis runs parallel to the longitudinal axis of the rotor blade and that the control unit can execute torsional movements about its longitudinal axis without mechanical control.

In a preferred embodiment, the control unit is integrated in the rotor blade and has a wing piston which is rotatably mounted in an inner ring attached to one fitting side and whose wing is firmly connected to the other fitting of the section of the rotor blade to be connected and which carries out rotary movements under the influence of a hydraulic fluid, the size of the rotary movement being limited by a recess provided in the inner ring.

The inner ring is surrounded by an outer ring, ^O which is firmly connected to the rotor blade on one side.

In another advantageous embodiment, the control unit is arranged outside the rotor blade such that the fixed part of one end is connected to the blade connection fitting and the rotatable part of the other end is connected to the rotor blade.

To increase redundancy, it is advantageous if a multiple control units are arranged one behind the other in the axial direction and all control units are hydraulically actuated either simultaneously or individually.

To avoid overheating of the hydraulic fluid, each supply and return line can be assigned a secondary line in order to ensure a continuous flow of the

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hydraulic fluid.

This known device therefore has the advantage of directly controlling the respective rotor blades, which means that the use of the technically complex and expensive swash plate is no longer necessary. The device has lower air resistance and a simpler rotor head structure due to the elimination of the usual mechanical control parts. Such a rotor blade control also makes it possible to react more effectively to backflows in the rotor orbit area and to superimposed gusts. This is particularly advantageous when influencing the rotor blade vibrations of the rotor blades running against the direction of flight.

The invention is explained in more detail below with reference to the drawing, in which advantageous embodiments are shown. The drawing shows:

Figure 1 is a perspective view of a device according to the invention for controlling the rotor blades;

Figure 2 is a section along the line A-B of Figure 1;

Figure 3 shows a first embodiment of the installation of control units in a rotor blade;

Figure 4 shows an installation example for a single-spar blade neck;

Figure 5 an installation example for a two-spar blade neck

Figure 6 is a side view of another embodiment and

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Figure 7 is a plan view of the embodiment shown in Figure 6.

Figure 1 shows a perspective enlarged, partially broken view of a control unit according to the invention, which in this case is integrated into a rotor blade 2 in such a way that the longitudinal axis of the control unit 1

runs parallel to the longitudinal axis of the rotor blade. The control unit 1 has, as can be seen in particular from Figure 2, a vane piston 3 which is arranged to rotate in a fixed inner ring 4, e.g. made of bearing metal, which in turn is surrounded by an outer ring. The inner ring 4 is fixedly mounted in a connection fitting 6 or 7 which is connected to the rotor blade 2.

The inner ring 4 has an opening sector that is larger than the part of the wing piston 3 that projects into it, so that the latter can perform rotary movements in both directions

^ ^{ann and the} path of rotation is determined by the sum of the angles + oC and -cK. (Figure 2). In order to be able to carry out such rotary movements, hydraulic lines 8, 9 are connected to the control units in accordance with Figure 1 in such a way that one or the other gap between the wing of the wing piston and the inner ring 4 is supplied with hydraulic fluid. Since the wing piston 3 is firmly connected to the rotor blade 2, the section of the rotor blade 2 connected to this control unit is twisted downwards or upwards in the area of the control unit 1, depending on which of the gaps is supplied with hydraulic fluid. Instead of a wing piston with one wing (as shown), wing pistons with several wings can also be used. The length and diameter of the wing pistons ¹ ». can be freely selected and are only a function of the power requirement and the possible structural conditions of the rotor blade.

Because of the high centrifugal force that occurs, it is advisable

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to construct the outer casing in such a way that it acts as a closed vessel in the direction of centrifugal force. This achieves a force-locking support of the spar in the direction of centrifugal force on the outer casing and in the opposite direction via the piston vane. The maximum twisting that is given to the rotor blade spar is selected so that the torsional stresses f. do not reach critical values.

To avoid overheating of the hydraulic fluid, g;

it is advantageous if between the supply and return lines |

a bypass line (bypass) is laid to ensure a continuous

to ensure continued transport of the hydraulic fluid |

afford. f

Figure 3 shows an embodiment of a modern rotor blade which is connected directly to the rotor head 10 without a blade pivot bearing. This rotor blade 2 has a plurality of control units 11, 12, 13, 14, 15 arranged one behind the other in the axial direction in order to achieve a twisting of the rotor blade 2 over a larger length range. The control units are each connected to a common channel via their own hydraulic lines, so that any control units can be controlled using suitable hydraulic valves in order to generate one or more rotor blade twists. The control units can, however, also be operated simultaneously via a common hydraulic ^line in order to achieve a specific rotor blade twist over a larger area. Hydraulic lines 19, 20 which connect the rotor blade to the rotor head 10 are designated. Since these hydraulic lines rotate with the rotor head, there is a known connection within the rotor head between the rotating hydraulic lines and the helicopter-specific hydraulic lines.

Fig. 4 shows an example of a rotor blade with a single-hollow blade neck in which five control units 11, 12, 13/ 14/ 15 are arranged ^directly next to each other.

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-δ&igr; net sand, while in a further extension of the rotor blade 2 three control units 16, 17, 18 arranged at a distance from one another are provided in order to generate a twisting of the rotor blade 2 at these points, whereby the control of the individual control units takes place simultaneously or individually as described above.

Another embodiment of the arrangement of control units according to the invention is shown in Figures 6 and 7 - here the control unit 1 is not integrated into the rotor blade, but is arranged next to it and parallel to the axis of the rotor blade 2. Figure 7 in particular shows that the non-rotatable part of the control unit 1, i.e. the inner ring 4, is firmly connected at one end 21 to the blade connection 23, while the other end of the control unit 1 is connected via the blade piston 3 and a connecting device 22 to the spar of the rotor blade 2 in such a way that when the blade piston 3 is pivoted in the fixed inner ring 4, the rotor blade spar is twisted. Here, too, several control units can be arranged axially one behind the other. Here, too, by introducing the control units into the outer part of the rotor blade 2, blade pivoting can take place linearly or non-linearly during the blade rotation.

The invention therefore has the advantage of achieving higher harmonic control of the rotor blades and thus also enabling the control of a double harmonic oscillation in a rotor head with four rotor blades. The control unit according to the invention within the rotating system does not require any further mechanical control of the rotor blades in order to be able to generate one or more blade twists and to communicate these directly to the blade spar. Furthermore, twists can also be generated in the rotor blade beyond the blade neck. Instead of generating the required torsional force using hydraulic oil, other hydraulic transmission methods are also conceivable.

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Claims (7)

t ■ * · «»> ta r · ■ 4 · · * &ngr; j &bgr; ■ · r · , · · ■ · II13II· JJ · >■■!■· ·· 3 ■* * * 15.04.86 HFW2-Hf Device for controlling rotor blades &pgr; --t- &ldquor;&mdash;&khgr;. J lsprüche 1. Device for controlling rotor blades in a helicopter, whereby each rotor blade is movable relative to the angle of rotation of the rotor head, characterized in that each rotor blade has at least one control unit (1) which is connected to the rotor blade (2) in such a way that its longitudinal axis runs parallel to the longitudinal axis of the rotor blade and that the control unit can carry out torsional movements around its longitudinal axis without mechanical control. 2. Device according to claim 1, characterized in that the control unit is integrated in the rotor blade and has a wing piston (3) which is rotatably mounted in an inner ring (M) firmly connected to one fitting side and whose wing is firmly connected to the other fitting side of the section of the rotor blade (2) to be twisted and executes rotary movements under the action of a hydraulic fluid, the partial setting angle ( θ - θ) being limited by a recess provided in the inner ring. 3. Device according to claim 2, characterized in that the inner ring (4) is surrounded by an outer ring (5) which is firmly connected to the rotor blade and that each control unit (1) is mounted in at least two closure fittings (6, 7). A4 H 1 t I« 11*11114 t 4 I X(Il I · a·· «if <·< 4. Device according to claim 1, characterized in that the control unit is arranged outside the rotor blades in such a way that the fixed part of one end (21) is connected to the blade connection of the rotor head (10) and the rotating part of the other end (3) is connected to the rotor blade (2) via the parallel compensation (22)» 5. Device according to claim 1, characterized _in that a plurality of control units (11, 12, 13, 14, 15) are arranged one behind the other in the axial direction and that all control units can be hydraulically loaded simultaneously* e 6. Device according to claim 1, characterized in that a plurality of control units are arranged one behind the other in the axial direction and that each control unit has at least one valve for the individual hydraulic loading of selected control units. 7. Device according to claims 5 and 6, characterized in that several parallel rows of control units -t- arranged one behind the other in the axial direction are provided, each row having its own hydraulic supply and return line. &iacgr;. Device according to one of claims 5 to 7, characterized characterized in that each supply and return line is assigned a .,_ secondary line for the continuous flow of the hydraulic fluid.