1 Title of the Invention

SemirAutomatic Folding Device of Helicopter Rotor Blades.

2 Field of the Invention

The present invention relates to folding or Unfolding of Rotor blades for the helicopters where the rotor blades are in segmented form or have provision to rotate the blade about any particular hinge for folding of blades with minimum number of components removal. The helicopter should be able tp use immediately (without any correction, rigging or measurements etc.) as soon as blades are restored i.e., unfolding of blades, and secured with components that was dis-mantle for folding the blades,

3 Background of the Invention

The space occupied by Rotor of the Helicopters is a major concern for the users and it became challenging when situation occur for the Transportation, storage and Parking specially there is a limitation of space like on Ship deck or volume available in transport aircraft.

This invention provides a solution for the blade folding in a controlled manner with self-locking mechanism that ensure secured blade folding. Uncontrolled folding can lead to an accident due to slippage of blade and may lead to fatal accident.

3.1 Prior Art

US patent US6860450B2 titled “Apparatus and method for folding helicopter rotor blades for storage and transport of helicopter", 2005; (Figure 1), the folding of blade (60) with respect to rotor assembly using hinge (108), clamp (90) and blade positioning mechanism (86). The folding is achieved by the rotation pf handle (98) using hand or wrench. This system also uses additional swing link (170) as it has limited angle of blade folding. However, present invention provides a wide angle of blade folding without any additional link.
US patent 4712978 titled “Helicopter blade and the like stand-off and folding device”, 1987; (Figure 2), the folding of blade is done with help of device (10), the installation of device (10) can be done firstly by rotating the blade in opposite direction of required folding direction and then rotating the blade about retainer pin (28b,28c) to achieve folding in desired direction. It provides additional hinge with option of some tilt to avoid interference between other folded blades. However, present invention provides controlled positive folding mechanism.

US patent US 10287009 B2 titled “Helicopter blade folding apparatus", 2019; (Figure 3) provide additional support by using blade support beam assembly (46) which have additional hinge using quick lock pin (102), to avoid excess load on transport blade pin (56) of blade (42), and the folding process is uncontrolled and manually about hinge pin (102, 56), which is taken care in present invention with semi-automatic folding device.

4 Brief Summary of the Invention

The present embodiment works on four bar mechanism concepts with positive engagement of rack and Pinion. This device comprises two clamps one for fixed end and another for blade which is totally detachable and temporary, one link rod which further comprises spherical bearing to allow adjustment of any small misalignment between the links, one rack and one Handle that is detachable and same can be used to fold and unfold plurality of blades.

The Present invention permits easy, safe and controlled folding of the blades within minimal time span and efforts and the invention does not require any separate locking attachments or mechanism to secure the folded blade in its position during folding of blades, as the device (4) has inbuilt ratchet mechanism (not shown) to lock it.
5 Detail Description of the Invention

The features and components of the present invention are illustrated in Figure 1 to 10. However, the working and functions can be better understood by reading the detail description of the disclosed embodiment followed by the accompanied drawings in which, write brief description of each drawing, refer.example at Figure 6 and Figure 7.

Figure 1: Prior art- US patent US 6860450 B2 titled “Apparatus and method for folding helicopter rotor blades for storage and transport of helicopter”, 2005.

Figure 2: Prior art- US patent 4712978 titled “Helicopter blade and the like stand-off and folding device”, 1987.

Figure 3: Prior art- US patent US 10287009 B2 titled “Helicopter blade folding apparatus”, 2019.

Figure 4: Illustrates the helicopter and the systems like, fuselage (1), Rotor Blades (2), hub (3) and tail boom (5) etc.

Figure 5: Illustrate the two segmented rotor blade assembly which comprises the inner segment of fixed end (6), Blade (7) also refer as pr outer segment, connector (8), bolt or fastener (9,10), hole or axis of blade (11,12), hole or Axis of fixed end (1.3,14), washers (15), nuts (16).

Figure 6: Illustrate the device (4) in assembled condition which comprises removable handle (17), roller pipe (18,1.9), clamp for fixed end (20), clamp for blade (21), bolt for hinge (22,23), link rod with spherical bearing eye ends (24), rack (25), neck for blade clamp (26), neck for fixed end clamp (27), cover plate (28), screws for cover plate (29), lever for ratchet (30).

Figure 7: Illustrate the device (4) in exploded condition which comprises additional feature and components like non-circular engaging tip of handle (31), hole or groove (32), pinion with teeth or gears (33), teeth for ratchet locking (34), groove pr guide for rack (35), groove or seating for pinion
(36), nuts (37), bushes (38), washers (39), rack teeth (40), axis and lugs of rack (42), axis and lugs of .clamp (43), central axis (58).

Figure 8: Illustrate the Clamp for fixed end (21) in closed or locked condition which comprise upper half contour of the clamp (44), lower half contour of the clamp (45), cushion (46), hinge (47), groove or feature for locking (48), latch assembly (49), dimensions as per fixed end contour (50), clearance (51).

Figure 9: Illustrate the Clamp for fixed end (21) in open condition which comprises the clamp axis (52), dimension (53), and latch wire (54) and direction (57).

Figure 10: Illustrate the rotor blade in partial folded condition with help of Load (55) and direction (56) clockwise or anti-clockwise rotation,

6 Detail Description of the Invention

An apparatus for folding or unfolding a rotor blade (7) of a helicopter, where at least one hinge is available, or can be converted as hinge to fold or unfold the rotor blade. (Figure 5), which illustrate the two segmented rotor comprising blade or outer segment (7), inner segment (6) and both are assembled via connector (8) through the hole (11,13,12,14) using bolts (9,10) washers (15) and nuts (16). In this assembly any one of fastener (9 or 10) can be removed from the assembly and another bolt can work as hinge for folding depending on the requirement.

The detailed description of proposed invented device (4) (Figure 6,7) is shown in assembled condition and exploded view respectively. The invented device (4) comprises of a clamp for fixed end (20) and a clamp for blade (21), which are designed with the same contour, of their respected fitting or clamping positions, so there must not be any relative movements after clamping. The clamps (21,22) are linked to each other with help of link rod (24) rack (40) and pinion (33). The link rod (24) further comprises of eye ends with inbuilt spherical bearings at both ends meant
to take care of any misalignment during clamping. One of the clamps features lugs (43) and another clamp features grooves (35,36) that are compatible to rack (40) and pinion (33) respectively and ensuring their functionality.

The present invention device (4) is a set of two clamps (20,21) rack (40) link rod (24) pinion (33). The link rod (24) and rack (40), which can be assembled using bolts (22,23) washers (39) nuts (37). The lugs of rack (40) and clamp (21) are having bushes (38) to ensure good life of lugs and proper fitting of spherical bearing eye ends using grinding of bushes surface. The torque tightening value of the nuts must be such that it should work as proper hinge. The assembly of rack (40) with another side i.e., clamp (20) with pinion (33) is made using groove (35,36) for seating and functioning of rack (40) and pinion (33) respectively. The groove ensures the positive engagements of teeth or gears of rack and pinion this is packed by cover plate (28) and screws (29). The cover plate (28) further comprises ratchet lever (30) and ratchet mechanism (not shown) which engages the teeth for ratchet locking (34). The pinion (33) comprises ratchet teeth (34) and groove (32) for bowler hat shape frame detachable handle (17). This is a specific design to get multiple features from a single component, this combined feature gives the self-locking capability and ensure there will not be unfolding while folding and vice versa. The teeth of pinion (33) ensure positive, controlled and fast folding of blades. The blade can be folded form 0 degree to 145 degree by just three turns of handle (17) about central axis (58), however which may vary depending on module of gear or size of teeth.

Figure 8 illustrates the installed condition of clamp (21) and Figure 9 illustrates the installed condition of clamp (21). The clamp (21) comprises of first half of blade contour (44), another half of blade contour (45), full contour is covered by the cushion (46), that may be done using rubber or felt or any other cushioning material to avoid damage to original components, latch assembly (49) which further comprises hinge (47) for
locking or unlocking of toggle latch assembly, groove or feature for locking (48) the latch wire (54), bushes (38) and the neck for blade clamp (26) which may be part of any half clamp (21). The neck (26) of clamp (21) is designed with upper half and given appropriate height provide sufficient clearance from the fitting attachments to avoid any other components of helicopter like damper, or any other instrument which can restrict the installation of clamps or folding of blades. The dimension (53) is made tapered to ensure easy installation (Figure 3,9). The dimensions (50,53) and clearance (51) are designed to achieve interference fit between clamp and blade contour to ensure some clamping force to avoid any relative movements between clamp and blade after clamping. The difference in dimensions and cushioning material may produce sufficient spring effect on blade and clamp contour.

The installation of the clamps (20,21), (Figure 8,9) can be done with opening and locking of clamp about the hinge axis (52) via toggle latch assembly (49), locking also can be achieved by rapid pin retention or using standard fasteners. To locate and install the clamps, marking can be provided on the blade as well as on the fixed end to ensure proper location of installation.

The clamp for fixed end (20) comprises all same features and design logic as clamp for blade (21) below the neck (27). The clamp (20) comprises additional features like rack-pinion and ratchet locking mechanism. The feature can be interchanged between clamps, but in present invention the rack-pinion is kept at fixed end so it can avoid additional movements of hands along with blades during folding of blades.

The handle (17) which is totally removable and same can be used to fold or unfold number of blades and will not be on the helicopter after folding of blades. The handle (17) further comprises two roller pipes (18,19) and non-circular feature (31) that will engage with another non-circular groove (32). The nom circular feature (31,32) is compatible to each other and able
to rotate the pinion for folding of blade. The handle can be modified to reduce the torque requirement by operator by changing the dimension (17a), (Figure 6).

The present invention, (Figure 6), is designed as GHE (Ground Handing Equipment’s) for folding of blades. The clamps (20,21) of device (4) may be modified as per shape and size of the blades (7) and fixed ends (6). This mechanism can be used on any helicopters which have at least one hinge point to fold blade.

The proposed invented device (4) (figure 6) comprises clamps (20,21) hinge axis (42, 43) rack (40) pinion (33) and ratchet mechanism (not shown) are totally detachable and part of GHE. However, the device (4) can be a part of helicopter SOP (Standard Operating Procedure) completely or partially. The invented device (4) has limited angle of folding in opposite direction with respect to rack-pinion assembly, to overcome this limitation, the invented device (4) has a flexibility and the device can be installed on either side of blade by disengagement of rack-pinion and re-orientation of clamps (20, 21), by flipping about their own axis, and again engagement of rack-pinion assembly.

The method of folding or unfolding (Figure 10). The assembled device (4) (Figure 6) but without handle .{17) .can .be installed on helicopter to fold and unfold the rotor blade. The clamp (20) is installed to inner segment (6) and clamp (21) is installed to blade (7) using latch assembly, (Figure 8, 9). The installation of the clamps is to be done in such a way that rack is towards the bolt about which operator want to fold the blade, (Figure 10) for illustration, it’s about bolt (10). The bolt (9) needs to be removed and the bolt (10) is used as hinge for folding the blade by de-torquing nut (16). Further operator needs to set the ratchet lever to allow folding and restrict unfolding which may occur due to self-weight of blade or angle of tilt or human error etcetera. Engage the handle by matching (31,32) (Figure 7,10), Further to fold the blade, the operator needs to hold the pipe (1?)
and apply sufficient load (55) as in direction (Z) (Figure 1,10) and using another hand, hold the pipe (18) and start rotating the pipe (18) about central axis (58) as per direction (56) depending on direction required for folding the blade. The number of rotations of pipe (18) depends on the requirements of folding and the module of gears or teeth size of rack and pinion arrangement. If the user feels that the blade is heavy or the single hinged bolt (10) is not adequate to take load of blade self-weight the user may add some additional GHE to give external support. After folding of blade, remove or disengage the handle and the keep it secure in GHE kit. The above-mentioned procedure can be repeated to fold other blades of helicopter; However, the indexing of blades may be taken care if required. After folding all the blades, it is recommended to secure or Jock the blade in folded condition using some GHE.

For unfolding of blades, operator needs to remove all types of GHE (if any, which user may have installed to secure blades in folded condition or to reduce the excess load on bolt, used as hinge) except invented device (4). To unfold the blade, engage handle (17), switch the ratchet lever to allow unfolding, hold handle (17) with help of pipe (18,19), apply load (55) and rotate pipe (18) about central axis (58) in required direction. After unfolding assemble the bolt (9), disengage the handle (17), torque the blade assembly using fasteners (9-15) properly, uninstall the device (4).