Rotocraft rotor including a flapping abutment mechanism for blades hinged on a hub of the rotor

Patent metadata

Field	Value
Publication number	US-9586680-B2
Application number	US-201213693192-A
Country	US
Kind code	B2
Filing date	Dec 4, 2012
Priority date	Dec 7, 2011
Publication date	Mar 7, 2017
Grant date	Mar 7, 2017

Abstract

An abutment mechanism for limiting the flapping of the blades of a rotor ( 1 ). High abutment members ( 6 ) can be moved into an engagement position by return means ( 13 ) exerting an intrinsic return force (R), and into a disengagement position by a flyweight ( 10 ) exerting a centrifugal force (C) under the effect of the rotor ( 1 ) rotating. At least one magnetic type bistable latch ( 15 ) is in selective engagement with the high abutment members ( 6 ). When the rotor ( 1 ) is stationary and while it is starting to rotate, an engagement latch ( 15 ) engages with the high abutment member ( 6 ) to prevent it passing from the engagement position towards the disengagement position. At a predetermined centrifugal force threshold, the engagement of the engagement latch ( 15 ) with the high abutment member ( 6 ) is broken, and the high abutment member ( 6 ) quickly passes into the disengagement position.

First claim

What is claimed is:

1. An abutment mechanism for a rotorcraft rotor having a rotary wing comprising a plurality of blades, the blades being individually hinged to a hub of the rotor via respective mounting members, the abutment mechanism comprising:
abutment members that are mounted on the hub and that co-operate with first members carried by the hub including low abutment members and high abutment members between which the individual flapping path of a blade associated therewith is limited;
the high abutment members being movably mounted on the hub to move between an engagement position in which the high abutment members co-operate with corresponding contact members constituting an obstacle to the upward flapping path of the blades, and a disengagement position in which the high abutment members are retracted leaving the upward flapping path of the blades free;
the abutment mechanism comprising drive means for driving the high abutment members between the engagement position and the disengagement position, the drive means comprising first drive means and second drive means developing opposing forces causing the high abutment members to pass respectively towards the disengagement position and towards the engagement position;
the first drive means making use of centrifugal force to generate a centrifugal force (C) causing the high abutment members to pass towards the disengagement position as from a predetermined centrifugal force threshold (SC); and
the second drive means comprising return means that generate a spontaneous return force (R) for returning the high abutment members towards the engagement position against the centrifugal force (C) generated by the first drive means, the return means causing the high abutment members to pass towards the engagement position as from a predetermined return force threshold (SR) corresponding to a predetermined lessening of the centrifugal force (C) generated by the first drive means;
wherein the abutment mechanism comprises at least one bistable engagement latch that selectively engages the high abutment members between an active state of the engagement latch in which the engagement latch engages with the high abutment members that it keeps blocked in the engagement position, and an inactive state of the engagement latch in which the engagement is broken allowing the high abutment members free to move independently relative to the engagement latch; and
wherein the centrifugal threshold (SC) and the return force threshold (SR) are distinct previously-defined thresholds, and the centrifugal force threshold is significantly greater than the return force (R) intrinsically generated by the return means against the centrifugal force (C) generated by the first drive means at the centrifugal force threshold (SC).

2. The abutment mechanism according claim 1 , wherein the engagement latch takes up its inactive state at the centrifugal force threshold (SC) reached by the centrifugal force (C) that is progressively generated.

3. The abutment mechanism according to claim 2 , further including inhibit means comprising the first drive means for inhibiting the engagement latch causing it to take up its inactive state at the centrifugal force threshold (SC) reached by the centrifugal force (C) that is progressively generated by the first drive means.

4. The abutment mechanism according to claim 1 , including activation means for activating the engagement latch causing it to take up its active state at a centrifugal force (C) corresponding to a predetermined latching force threshold that is no greater than the return force threshold (SR).

5. The abutment mechanism according to claim 1 , wherein the engagement latch generates a retaining force (V) for retaining the high abutment members in the engagement position against the centrifugal force (C) generated by the first drive means, the retaining force (V) corresponding to the value of the centrifugal force threshold (SC) minus the return force (R) intrinsically generated by the return means at the centrifugal force threshold (SC).

6. The abutment mechanism according to claim 1 , wherein the engagement latch comprises first magnetic means associating at least one set of co-operating magnetic members that are engaged respectively with the high abutment members and with the hub.

7. The abutment mechanism according to claim 6 , wherein the engagement latch generates a retaining force (V) for retaining the high abutment members in the engagement position against the centrifugal force (C) generated by the first drive means, and wherein the engagement latch comprises at least one of the magnetic members developing a permanent and intrinsic magnetic force corresponding to the retaining force (V).

8. The abutment mechanism according to claim 6 , wherein the engagement latch comprises an electromagnet that operates under the dependency of control means for activating it and conversely for inhibiting it, the control means being in communication with means for evaluating the centrifugal force (C) generated by the first drive means relative to the centrifugal force threshold.

9. The abutment mechanism according to claim 1 , wherein the abutment mechanism includes damper means against the bounce phenomenon (Q) induced by the high abutment members passing rapidly from the engagement position towards the disengagement position.

10. The abutment mechanism according to claim 9 , wherein the damper means are formed by damper members placed on a path corresponding to the movement of the high abutment members from the engagement position to the disengagement position.

11. The abutment mechanism according to claim 9 , wherein the damper means are integrated in the return means.

12. The abutment mechanism according to claim 1 , including at least one bistable disengagement latch that selectively engages the high abutment members between an active state of the disengagement latch in which the disengagement latch engages with the high abutment members that it keeps blocked in the disengagement position, and an inactive state of the disengagement latch in which the engagement is broken leaving the high abutment members free to move independently relative to the disengagement latch.

13. A rotorcraft rotor having a rotary wing comprising blades hinged to a hub of the rotor, the rotorcraft rotor comprising:
an abutment mechanism for a rotorcraft rotor having a rotary wing comprising a plurality of blades, the blades being individually hinged to a hub of the rotor via respective mounting members, the abutment mechanism comprising:
abutment members that are mounted on the hub and that co-operate with first members carried by the hub including low abutment members and high abutment members between which the individual flapping path of a blade associated therewith is limited;
the high abutment members being movably mounted on the hub to move between an engagement position in which the high abutment members co-operate with corresponding contact members constituting an obstacle to the upward flapping path of the blades, and a disengagement position in which the high abutment members are retracted leaving the upward flapping path of the blades free;
the abutment mechanism comprising drive means for driving the high abutment members between the engagement position and the disengagement position, the drive means comprising first drive means and second drive means developing opposing forces causing the high abutment members to pass respectively towards the disengagement position and towards the engagement position;
the first drive means making use of centrifugal force to generate a centrifugal force (C) causing the high abutment me

Assignees

• Airbus Helicopters

Inventors

• Mondet Jean

Classifications

• B64C27/322 Primary

  Blade travel limiting devices, e.g. droop stops · CPC title

• B64C27/57 Primary

  automatic or condition responsive, e.g. responsive to rotor speed, torque or thrust · CPC title