Device and method for folding and spreading rotor blade pivot joints

Abstract

Device for folding and spreading rotor blade folding joints on a removed or hydraulically clamped main rotor head of a helicopter, characterized in that - the device is reversibly attached to the main rotor in the area of a removed dome cover when in operational condition, - is connected to the hydraulic lines of a rotor blade folding device due to its spatial proximity and - the device is supplied with external hydraulic power.

Description

[0001] The invention relates to a device for folding and spreading individual blade pivot joints on the removed or hydraulically clamped main rotor head of a helicopter.

[0002] Blade swivels on helicopters are already known. Especially for helicopters that are housed in confined spaces, such as on ships or in hangars, the space required by a helicopter can be significantly reduced by folding the rotor blades.

[0003] For example, from patent specification DE 12 60 317 A, a device is known for folding in and out a rotary wing blade, which has a pivot joint and a folding joint extending outwards from the pivot joint, and for locking the blade in its folded-out position as well as for locking the setting angle of the blade during folding in and out, characterized in that, for folding in the blade, an arm is pivotable about the folding axis by a torque acting between the arm and the blade, which is initially blocked against rotation about the folding axis, and acts via a first link on a first lever, which is seated in a rotationally fixed manner on a shaft rotatable in the bearing housing for the setting angle shaft of the blade, on which a second lever is fastened, which, via a second link, displaces a pin, known per se, guided parallel to the blade spar.whereby the end thereof facing the rotor hub enters a bore of a shoulder of the setting angle shaft, as is also known per se, and then strikes against a stop on the connecting piece between the swivel joint and the rotor hub, whereupon the further pivoting of the arm and the resulting further extension of the second lever and the second link relative to each other causes the blade with the bearing housing to undergo a partial pivoting about its pivot axis until the second lever strikes the bearing housing, whereupon the continued effect of the torque now causes the blade, which has since been unblocked by an additional device, to pivot about its folding axis.

[0004] When the helicopter is operational, the process is hydraulic. Both the safety and locking pins, and finally the rotor and rotor blade movement, are operated using onboard hydraulic power. These processes are complex, and the solution to the problem has already led to patentable solutions.

[0005] For example, British publication GB 781 356 A discloses a helicopter having a rotor, each of a plurality of blades of the rotor being provided with hinge means on the axis about which the blade can be folded, and with means for locking the hinge means movable between a locking position in which the blade is locked in the flight position and an unlocked position in which the blade can be freely folded, with means responsive to unlocking of the locking means for folding the blades, and with means responsive to movement of the blades from the folded position to the deployed position for moving the locking means to the locking position.

[0006] The teaching of US patent US 3 218 027 A relates to a hydraulic valve control and in particular to a hydraulic valve control for determining the position of a movable element with respect to a predetermined position and for controlling the fluid flow through the valve so that the element is returned to the predetermined position.

[0007] From the worldwide patent application WO 2010 / 141 132 A2, a proximity sensor valve is known, comprising a housing defining a fluid inlet and a fluid outlet in communication with a cavity. A plunger pin within the cavity for movement along an axis, wherein the plunger pin is movable between an extended position and a retracted position. In the fully extended position, the piston pin protrudes at least partially from the housing. Located within the cavity is a slider which is movable along the same axis as the piston pin, such that the slider and the piston pin are movable relative to each other to control the fluid flow between the fluid inlet and the fluid outlet.

[0008] Most recently, US Patent Application Publication US 2012 / 0 121 412 A1 discloses a rotor blade folding system for an aircraft, comprising one or more actuators connected to one or more blade components of one or more rotor blades of the aircraft. One or more sensors are located on the rotor blades and detect their operation. A folding control system monitors the sensor output and can stop the operation of the blade folding system via communication with the actuator if the blade components do not operate within specified limits.

[0009] All of these control and regulation elements have the disadvantage that they only function when installed and the helicopter's hydraulic system is functioning. The main rotor / rotor head has up to six blade pivot joints (BDG), which in turn have a rotor blade folding joint. When the rotor blade folding joints are open, the main rotor is folded. All blades lie longitudinally against the aircraft. When the joints are closed, the main rotor is spread, meaning it is in the flight position.

[0010] If the main rotor is removed, for example, for maintenance purposes, all adjustment and control processes must be performed manually, one after the other, using special tools. This work is laborious and time-consuming.

[0011] The object of the invention is therefore to present a device that enables a simple, uniform and understandable "opening / folding" and "closing / spreading" of a blade pivot joint without the use of mechanically acting special tools for actuating the locking bolts and rotor folding lock cylinders.

[0012] This object is achieved by the characterizing features of the main claim and the dependent claim 3. Advantageous embodiments are described in dependent claim 2.

[0013] The advantage of the invention is that a device for folding and spreading rotor blade pivot joints of dismantled helicopter main rotors is reversibly attached to the main rotor but does not perform any mechanical actuation. While known devices move the hydraulic components of the main rotor mechanically, the device according to the invention utilizes the existing hydraulic system. Advantageously, this procedure eliminates the need to use mounting devices such as protective caps, threads, or the like, which could potentially be destroyed, nor does it provoke dry running of the hydraulic components. Furthermore, the use of the existing hydraulic components allows for rapid actuation of the rotor blade pivot joints while simultaneously testing the functionality and leak-tightness of the system.

[0014] For the adaptation of the special mechanical tools, interfaces are provided that must be protected from wear, corrosion, and even destruction. Covers such as caps or hoods, paints, and similar measures are often destroyed during assembly and disassembly and must be replaced. The device enables a method for operating the rotor blade folding joints without having to use the mechanical interfaces for special tools.

[0015] A further advantage is that the system is pressurized with hydraulic oil, which, unlike conventional mechanically operated special tools, allows only a small amount of air to enter the system. Air ingress poses the risk of dry running and air compression when operating the hydraulic actuators of the rotor blade folding device, which in turn can lead to damage or destruction of seals.

[0016] The special mechanical tools for operating the locking and adjusting devices of the rotor blade folding system are individually attached and removed from each element. This requires a considerable amount of time during repairs. With the device according to the invention, all locking bolts and rotor folding lock cylinders, as well as the adjusting elements, can be operated simultaneously. The use of several devices according to the invention also makes it possible to operate a correspondingly larger number of rotor blade folding joints simultaneously, provided this is advantageous for maintenance and inspection work, for example, during visual or leak testing of the entire system.

[0017] A further advantage of the invention is that the device's design is geared toward bringing the device's own interfaces close to the area of the main rotor-side interfaces, so that the hose lines are not confused due to the close spacing between corresponding interfaces. According to the invention, the interfaces or screw connections are positioned so that the original hose connections are used. Equally advantageous is the design of the interfaces or screw connections such that the threads point in the direction of the hose line to be connected.

[0018] The device according to the invention is designed such that interfaces that are used, for example, for the same function are located spatially in the same area of the device. This means that hydraulic screw connections that are connected to the pressure line for the "open / fold" function are located in the upper area of the device in the operational state, while the connections for the return line are then located accordingly in the lower area. For the "close / spread" function, the corresponding connections must be actuated in the opposite position. This arrangement also enables simple visual inspection of the correct installation situation. This advantageous embodiment is described in subclaim 3.

[0019] For better understanding, the following functional sequence is described: The device is attached with two enclosed screws above the respective blade swivel joint (BDG) on the distributor ring, where the dome cover is otherwise screwed on. Next, the four hydraulic lines (2 pleated, 2 spread) are removed from the distributor ring and attached to the fixture above. The exposed sealing plugs are screwed onto the bottom of the distributor ring to protect the lines from dirt. To open the blade pivot:

[0020] Connect the high-pressure pump to the "folding pressure" connection. Connect the return line to the "expanding pressure" connection. Continue pumping with the high-pressure pump until the BDG opens and the folding end position locks are locked. To close the blade pivot:

[0021] Connect the high-pressure pump to the "expansion pressure" connection. Connect the return line to the "folding pressure" connection. Continue pumping with the high-pressure pump until the BDG is closed and the rotor folding lock pistons are locked by the locking bolts.

[0022] After the "closing / spreading" process, the hydraulic pump and return line are disconnected from the device. The four hydraulic lines (2 folds, 2 spreads) are connected from the device to the distribution ring. The device is dismantled.

[0023] It shows Fig. 1 shows a device according to the invention mounted on the main rotor. Fig. 2 the device according to the invention connected to the hydraulic system of a rotor blade pivot joint. Fig. 1 shows a device according to the invention for folding and spreading rotor blade pivot joints, screwed to the distributor ring 2 of the main rotor on the fastening tabs of the dome cover. Four hydraulic connections 3-6 are located on the distributor ring 2 for each rotor blade pivot joint. The expansion line 1 connection on the distributor ring 3 and the expansion line 2 connection on the distributor ring 4 carry the pressure oil for closing / spreading the rotor blade due to the system. The folding line 1 connection on the distributor ring 5 and the folding line 2 connection on the distributor ring 6 carry the return oil during spreading. During folding, the folding line 1 connection on the distributor ring 5 and the folding line 2 connection on the distributor ring 6 carry the pressure oil, and the expansion line 1 connection on the distributor ring 3 and the expansion line 2 connection on the distributor ring 4 carry the return oil. The device 1 has six hydraulic connections 7-12, with the hydraulic connections 7-10 being located above the folding line and the return oil connections.The expansion line is located on the distribution ring 3-6 and is functionally assigned to it. The connection for the folding pressure 11 and the connection for the expansion pressure 12 are optionally connected to the pressure or return connection of the hydraulic device, for example, a pump (not shown here). The functionally related connections for the folding pressure 7, 8, and 11 are located in the upper area of the device, while the connections for the expansion pressure 9, 10, and 12 are located in the lower area. It shows Fig.2 shows a device 1 according to the invention. The hose lines of the expansion line and folding line connections on the distribution ring 3-6 were connected to the expansion line and folding line connections on the device 7-10 of the device 1. The dust covers of the expansion line and folding line connections on the device 7-10 were screwed onto the exposed expansion line and folding line connections on the distribution ring 3-6 for protection. The connection for the folding pressure 11 and the connection for the expansion pressure 12 are to be connected to the hydraulic device, for example a pump, and the return line, depending on the "close / spread" or "open / fold" function. List of reference symbols 1 device 2 distribution ring 3 (spreading line 1 on the distribution ring) 4 (spreading line 2 on the distribution ring) 5 (folding line 1 on the distribution ring) 6 (folding line 2 on the distribution ring) 7 (folding line 1 on the device) 8 (folding line 2 on the device) 9 (spreading line 1 on the device) 10 (spreading line 2 on the device) 11 (Connection for the folding pressure or return expansion pressure) 12 (connection for the expansion pressure or return folding pressure)

Claims

[1] Device for folding and spreading rotor blade folding joints on a removed or hydraulically clamped main rotor head of a helicopter, characterized by , that - the device is reversibly attached to the main rotor in the area of a removed dome cover when in operational condition, - is connected to the hydraulic lines of a rotor blade folding device due to its spatial proximity and - the device is supplied with external hydraulic power. [2] Device according to one of claims 1 and 2, characterized by that the arrangement of the hydraulic fittings on the device indicates the function. [3] Method for folding and spreading rotor blade folding joints on a removed or hydraulically disconnected main rotor head of a helicopter, characterized by , that - the device is attached above the respective blade pivot to a distributor ring, where the dome cover is usually screwed on, - four hydraulic lines (2x folds, 2x spreads) are removed from the distributor ring and screwed onto the device above, - the released sealing plugs are screwed onto the bottom of the distributor ring, - a high-pressure pump is connected to a “spreading pressure” connection of the device, - a return line is connected to a “folding pressure” connection and - the high-pressure pump is pumped until the rotor blade folding joints of the blade pivot joint are closed and the rotor folding lock pistons are locked by the locking bolts or - the high-pressure pump is connected to a “folding pressure” connection of the device, - a return line is connected to a “spreading pressure” connection and - the high-pressure pump is pumped until the rotor blade folding joints of the blade pivot joint are opened and the folding end position locks are locked, - after opening or spreading, the four hydraulic lines from the device are connected to the distribution ring, - the high-pressure pump is separated from the device and - the device is separated from the main rotor head.

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