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EP-3941827-B1 - ROTOR BLADES OF A LIFT ROTOR

EP3941827B1EP 3941827 B1EP3941827 B1EP 3941827B1EP-3941827-B1

Inventors

  • WEGERIF, Robert Christiaan
  • SOETHOUDT, Wouter Adriaan
  • VAN RIJN, Louis Petrus Valentjin Marie
  • STEKELENBURG, MICHAEL ALWIN WILLIAM

Dates

Publication Date
20260506
Application Date
20200318

Claims (12)

  1. Vehicle (100) with a lift rotor (150) having foldable rotor blades (152, 153), wherein the number of rotor blades is equal to two, each rotor blade : comprising a hinge element (173; 240) defining two hinge axes arranged in parallel, and two blade segments (171, 172) each coupled to the hinge element (173; 240) for hinging with respect to a respective one of said hinge axes; wherein the rotor blade has an extended condition in which the blade segments are substantially aligned with each other; and wherein the rotor blade has a folded condition in which each blade segment is hinged with respect to the hinge element so that the blade segments are substantially parallel to each other; wherein the blade has a chord (14) and wherein said hinge axes are substantially parallel to the chord (14); wherein the hinge element (240) has - a central body (241); - at least one first coupling flange (242) extending away from the centra! body (241) in a first direction, with a first cylindrical hole (244) extending perpendicular through the first flange (242); - at least one second coupling flange (243) extending away from the central body (241) in an opposite second direction, with a second cylindrical hole (245) extending perpendicular through the second flange (243); wherein a first one of said blade segments (171) has at one end a hinge portion (212) comprising at least one coupling flange (213) and a cylindrical hole (214) extending perpendicular through the coupling flanges (213); wherein a second one of said blade segments (172) has at one end a hinge portion (272) comprising at least one coupling flange (273) and a cylindrical hole (274) extending perpendicular through the coupling flange (273); and wherein the rotor blade further comprises - a first cylindrical hinge axle (251) arranged in the aligned holes (214, 244) of the first blade segment (171) and the hinge element (240), respectively; and - a second cylindrical hinge axle (252) arranged the aligned holes (274, 245) of the second blade segment (172) and the hinge element (240), respectively; the vehicle having a vehicle body (110) and a mast (140) hinged to the vehicle body (110); wherein the lift rotor (150) comprises a rotor hub (151) mounted at a top end (142) of the mast (140), such that the rotation axis of the hub is fixed with respect to the mast ; and wherein each foldable rotor blade has its proximal blade segment (171) hinged to the rotor hub, wherein a hub hinge axis (154, 155) between the hub (151) and the proximal blade segment (171) is substantially parallel to the chord (14) of the rotor blade; wherein the rotor blades have a length larger than the length of the vehicle body (110); wherein the vehicle has a flying condition in which: - the mast is in an upright position, - the two rotor blades have their chord plane directed horizontally; and wherein the vehicle has a compact condition for road travel in which: - the mast (140) is lowered to a horizontal position, - the rotation axis of the hub (151) is directed horizontally; - the proximal blade segment (171) extends parallel to the mast (140) from the hub (151) to the rear end of the vehicle body (110), - the hub hinge axis (154, 155) extends vertically, - the chord (14) of the rotor blade is directed vertically.
  2. Vehicle according to claim 1, wherein the extended condition of the rotor blade is defined by at least one stop between the hinge element and at least one of the blade segments.
  3. Vehicle according to claim 1 or 2, wherein the blade segments (171, 172) have upper surfaces (171u, 172u) which in the folded condition are facing each other, and which in the extended condition are flush with each other and the intermediate hinge element (240).
  4. Vehicle according to any of previous claims 1-3, further comprising a preferential folding control arrangement (300) to ensure a preferred hinging order of the first blade segment (171) and the second blade segment (172).
  5. Vehicle according to claim 4, wherein the preferential folding control arrangement (300) has a first locking condition in which it locks the first blade segment (171) in its extended condition with respect to the hinge element (240) and allows hinging of the second blade segment (172).
  6. Vehicle according to claim 4 or 5, wherein the preferential folding control arrangement (300) has a second locking condition in which it locks the second blade segment (172) its folded condition with respect to the hinge element (240) and allows hinging of the first blade segment (171).
  7. Vehicle according to any of claims 4-6, wherein the hinge element (240) has an axially displaceable locking pen (330) having a first end and an opposite second end, wherein either said first end engages the first blade segment (171) to lock it or the second end engages the second blade segment (172) to lock it.
  8. Vehicle according to claim 7, wherein said first end and said second end each have a bevelled edge.
  9. Vehicle according to claim 7 or 8, further comprising a bias member (340), arranged tor exerting a bias force on the lock pin (330).
  10. Vehicle according to any of the previous claims, wherein the vehicle is a convertible vehicle having a flying condition and a road traffic condition; wherein in the flying condition the mast (140) is standing upright and the rotor blades are in their extended condition and are directed away from the rotor hub (151) in opposite directions; and wherein in the road traffic condition the mast (140) is hinged down to a substantially horizontal direction, and wherein each foldable rotor blade is in its folded condition with its proximal blade segment (171) hinged towards the mast (140).
  11. Method for converting the vehicle according to any of the previous claims from the flying condition to the road traffic condition, the method comprising the steps of: - positioning the rotor blades to extend in transverse direction with respect to the vehicle; - hinging the mast forward from a substantial vertical orientation to a substantial horizontal orientation, so that respective hinge axes of the rotor blades are directed substantially vertical; - folding the rotor blades about the respective hinge axes with respect to each other and with respect to the hub, so that the proximal blade segments are directed from the hub to the rear of the vehicle and the distal blade segments are directed forward, to eventually reach a position in which the blade segments are directed parallel to each other, in longitudinal direction of the vehicle, parallel to the mast; in this order.
  12. Vehicle according to any of the previous claims 1-10, wherein the vehicle is adapted to be converted from the flying condition to the road traffic condition by the method of claim 11.

Description

FIELD OF THE INVENTION The present invention relates in general to rotor blades of a lift rotor. In the context of the present invention, a "lift rotor" is a rotor providing lift force to a flying vehicle, such as for instance a helicopter, or a gyrocopter. The invention relates particularly to the field of convertible vehicles that have a flying condition and a road traffic condition. BACKGROUND OF THE INVENTION Generally, the length of a rotor blade is much longer than the width or length of the vehicle concerned. Such length translates to an amount of floor space occupied by the vehicle when standing still. In certain circumstances, it is desirable to reduce that space, for instance when being parked in a shelter or when being transported in a truck or airplane. For rotors having two blades, it is possible to reduce the width of the overall vehicle by aligning the rotor blades with the longitudinal direction of the vehicle. If that does not suffice, it is known to remove the rotor blades, which does however require hoisting equipment and/or the need for personnel to climb on top of the vehicle. An example of a vehicle with lift rotor can be found in document US 9566839 B2. SUMMARY OF THE INVENTION Solutions such as described above are not suitable for convertible vehicles. By the very nature of such vehicles, it is essential that they can be converted from a flying condition to a road traffic condition in a relatively simple and quick manner, by a single person remaining standing on the floor. Further, in the road traffic condition, it is not intended that the rotor blades are left behind, hence removing the blades is not a preferred solution. Further, in the road traffic condition, merely positioning the rotor such that the rotor blades are aligned longitudinally in opposite direction is not a suitable solution. The vehicle as a whole should, in the road traffic condition, comply with road traffic regulations, have a low centre of gravity, have a low air resistance, etc. Said requirements can, up to a point, be met if the rotor blades are hinged to a central rotor hub, and are with respect to this central hub hinged to a mutually parallel position, i.e. in the same direction parallel to the longitudinal direction of the vehicle. Nevertheless, for performing in flying condition, a relatively large blade length is desirable, while the vehicle body is desirably compact so that large blades would, apart from being an aerodynamic problem, pose the problem of projecting beyond the vehicles contours. Therefore, the present invention proposes to have each rotor blade be foldable. The above objectives are obtained by a vehicle according to claim 1 and a method according to claim 11. Figure 1A shows a schematic top view of a rotor blade 10. It can be seen that rotor blades are elongate with a relatively large length and a relative small width. The rotor blade 10 has a proximal end 11 adapted for connection to a rotor hub (not shown), and an opposite distal free end 12. A quarter chord line connecting the proximal end 11 and distal end 12 will be indicated as blade centre line 13, and its length determines the length of the rotor blade 10. Figure 1B shows a schematic cross section of the rotor blade 10, in a plane perpendicular to the blade centre line 13. The blade has an aerodynamic wing profile, with a leading edge 16 and a trailing edge 15. A straight line connecting the leading edge 16 and trailing edge 15 will be indicated as chord 14. It can be seen that the length of the chord 14 is larger than the largest thickness of the blade 10, measured in a direction perpendicular to the chord 14 and to the blade centre line 13. In the following, a virtual plane defined by the chord 14 and the blade centre line 13 will be indicated as a chord plane 17. It is noted that, in operation, the rotor blade 10 will be rotating around a substantially vertical rotation axis, with the chord plane 17 directed substantially horizontally. According to an important aspect of the present invention, the rotor blade comprises, between its proximal end and distal free end, a hinge structure having a hinge axis substantially parallel to the chord plane 17, perpendicular to the blade centre line 13. Such hinge structure allows the rotor blade to be folded about an axis substantially parallel to chord 14. In an operational position, the rotor blade 10 is positioned at a relatively large height above ground, if only to provide sufficient ground clearing. Chord 14 will be substantially horizontal. Folding the rotor blade while being in this operational position would require a hinging action in a vertical plane, which would be difficult if not impossible for a person standing on the ground. In a vehicle according to the present invention, a rotor hub is mounted at the top of a mast positioned above the vehicle. The lower end of the mast is hinged with respect to the vehicle, so that the mast can be lowered to a substantially horizontal posi