Torque balancing rotor for a helicopter

Abstract

To provide an anti-torque rotor for a helicopter.SOLUTION: An anti-torque rotor 4 includes: a mast 6 rotatable about a first axis A; a plurality of blades 8 rotatable about respective second axes B; an element 16 being slidable relatively to the mast along the first axis, rotating integrally with the mast, and operatively connected to the blades; a control rod 10 slidable along the first axis; a first ring 30 rotating integrally with the element; a second ring 31 radially internal to the first ring with respect to the first axis; a first bearing 17 with a plurality of first rolling bodies; a third ring 50 sliding along the first axis integrally with the control rod and angularly fixed with respect to the first axis; and a locking element 55 that is arranged in a standard configuration to prevent the relative rotation of the second and third rings, and is movable from the standard configuration to an emergency configuration to render the second ring free to rotate with respect to the third ring when the first bearing is in a failure condition.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] Cross - reference to related applications This patent application claims priority from European Patent Application No. 19182720.3, filed on June 26, 2019, the entire disclosure of which is incorporated herein by reference.

[0002] The present invention relates to a torque - balancing rotor for a helicopter.

Background Art

[0003] A helicopter is basically known to comprise a fuselage, a main rotor disposed on the upper part of the fuselage and rotatable about the axis of the fuselage, and a torque - balancing rotor disposed at the tail end of the fuselage.

[0004] In known techniques, a helicopter may also comprise one or more power units, such as a turbine, and a transmission unit interposed between the turbine and the main rotor and adapted to transmit the motive power from the turbine to the main rotor itself.

[0005] More specifically, the torque - balancing rotor further basically comprises - a mast rotatable about a first axis, - a hub rotatable about the first axis, - a plurality of blade plates hingedly fixed to the hub, protruding from the hub in a cantilever beam manner, and each extending along a respective second axis transverse to the first axis and basically comprises.

[0006] The mast of the torque - balancing rotor is rotationally driven by a set of gears driven by the main transmission unit.

[0007] The blade plates of the torque - balancing rotor rotate integrally with the mast about the first axis and can be selectively tilted about the second axis so as to change their respective angles of attack, and as a result, the thrust exerted by the torque - balancing rotor can be adjusted.

[0008] To adjust the angle of attack of each wing plate, the torque balance rotor is - operably connected to a pedal operable by a pilot through a mechanical connection or fly-by-wire link, a rod that slides inside the mast along a first axis but is angularly fixed with respect to the first axis, and - a control element, also known as a "spider", that is integrally rotatable with the mast about a first axis and is equipped with a plurality of arms connected to respective wing plates at eccentric positions with respect to an associated second axis, and - a rolling bearing mounted in a manner that slides with respect to the first axis, interposed between the rod and the control element, and configured to transmit an axial load from the rod to a rotatable element and includes.

[0009] More specifically, the rolling bearing further includes - a radially outer ring fastened to the control element, and - a radially inner ring fastened to the control rod, and - a plurality of rolling elements that roll in respective orbits defined by the radially inner ring and the radially outer ring and includes.

[0010] In the normal operating state of the bearing, the rolling elements allow rotation of the outer ring with respect to the inner ring, and as a result, rotation of the control element with respect to the rod.

[0011] By the operation of the pedal, the control rod is slid parallel to the first axis. This sliding causes, via the rolling bearing, the control element to slide parallel to the first axis along a given path of travel.

[0012] This sliding causes rotation of the wing plates about the associated second axis, thereby changing the angle of attack of each by an equal amount associated with the given path of travel.

[0013] From the foregoing, the possible defects of the rolling bearing risk making the torque balance rotor substantially uncontrollable, leading to a dangerous situation for the helicopter.

[0014] Specifically, the defective situation may occur, for example, when the rolling elements and / or raceways of the inner or outer rings are damaged due to accidental entrainment of foreign objects into the bearing, loss of lubricating grease, or damage to the raceways or surfaces of the rolling elements.

[0015] In this state, instead of allowing relative rotation of the control element to the control rod, the rolling bearing will inappropriately transmit a torsional moment that gradually increases over time from the outer ring to the inner ring.

[0016] This torsional moment is transmitted to the control rod, creating a risk of damaging the control rod.

[0017] Prior to the defective state of the rolling bearing, there is usually an increase in the torque acting on the inner ring, as well as an increase in temperature and vibration in the area around the rolling bearing.

[0018] The need to reduce the risk of these defective states that disable the adjustment of the blade pitch angle, thereby making the thrust of the torque balance rotor and the yaw angle of the helicopter substantially uncontrollable, is recognized within the industry.

[0019] The need to ensure proper control of the torque balance rotor even in the event of a rolling bearing defect is also recognized within the industry.

[0020] Finally, the need to quickly identify the initial defective state of the rolling bearing and the need to provide clear and prompt instructions to the crew are recognized within the industry.

[0021] U.S. Patent No. 9,359,073 (B) describes a torque balance rotor for a helicopter according to the preambles of claims 1, 16, 28, 35, 46, 57, and 69.

[0022] More specifically, U.S. Patent No. 9,359,073(B) describes a torque balancing rotor comprising a mast, a rod, and first and second bearings arranged in series.

[0023] The first bearing comprises a first ring rotatable with the mast and a second ring.

[0024] The second bearing comprises a third ring and a fourth ring.

[0025] The third ring of the second bearing and the first ring of the first bearing are connected to each other in a non-rotatable manner.

[0026] Specifically, the first ring and the second ring respectively define a first track and a second track for the first rolling elements of the first bearing.

[0027] The third ring and the fourth ring respectively define a third track and a fourth track for the second rolling elements.

[0028] In other words, each of the first, second, third, and fourth rings defines its respective first, second, third, and fourth tracks. The torque balancing rotor also includes a locking device interposed between the third ring and the fourth ring and adapted to prevent rotation of the third ring relative to the fourth ring. This locking device comprises an element that is breakable in the event of a failure of the first bearing and not breakable in the event of correct operation of the first bearing.

[0029] The solution shown in U.S. Patent No. 9,359,073(B) is particularly complex because it requires the use of two rolling bearings and a locking device.

[0030] Specifically, the solution shown in U.S. Patent No. 9,359,073(B) requires four rings to define four tracks, and the first bearing and the second bearing are axially spaced apart from each other.

[0031] This makes the solution shown in U.S. Patent No. 9,359,073(B) particularly cumbersome and inappropriate for easily adapting to the small axial dimensions of the tail rotor of a helicopter.

[0032] Furthermore, both the first bearing and the second bearing comprise a single ring of spherical rolling elements.

[0033] By making the single ring of rolling elements have a low rotational stiffness, the breakable elements of the locking device can only transmit an axial load parallel to the rotational axis of the mast.

[0034] Therefore, the solution shown in U.S. Patent No. 9,359,073(B) is effective only when transmitting substantially only loads parallel to the rotational axis of the mast.

[0035] Furthermore, the use of a single ring of spherical rolling elements inevitably results in the presence of axial loads, which can consequently lead to unpleasant vibrations and noise.

[0036] Furthermore, due to the presence of a single ring of spherical rolling elements, the bearings in the figure are particularly exposed to the mechanism of false brinelling wear damage, i.e., wear in the form of hollows similar to Brinell hollows, caused by vibrations and rocking at the contact points between the rolling elements and the raceways, resulting in the occurrence of hollow scars.

Prior Art Documents

Patent Documents

[0037]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0038] An object of the present invention is to provide a torque-balanced rotor that can satisfy at least one of the above-mentioned requirements by a simple and inexpensive method. **Means for Solving the Problem**

[0039] The above object is achieved by the present invention as long as it relates to a torque-balanced rotor as defined in claims 1, 16, 28, 35, 46, 57, and 69.

[0040] For a better understanding of the present invention, three preferred embodiments are described hereinafter with reference to the accompanying drawings, using non-limiting examples of pure water. **Brief Description of the Drawings**

[0041]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

Figure 16

Figure 17

Mode for Carrying Out the Invention

[0042] Referring to FIG. 1, reference numeral 1 indicates - the airframe 2, - one or more turbines 5, - the main rotor 3 disposed above the airframe 2 and rotatable about axis A, - the torque balancing rotor 4 positioned at the tail end of the airframe 2 and rotatable about an axis transverse to axis A and basically indicates a helicopter comprising.

[0043] The helicopter 1 also includes a transmission unit, which is known per se and transmits the motive power from the turbine 5 to the main rotor 3 and is not shown in the figure.

[0044] Furthermore, the transmission unit includes - a gear train that transmits the motive power from the turbine 5 to the main rotor 3, - a shaft 13 that transmits the motive power from the gear train 12 to the torque balancing rotor 4 and comprises.

[0045] In known techniques, the main rotor 3 is adapted to provide a steerable thrust that enables the helicopter 1 to take off and fly forward.

[0046] The torque balance rotor 4 generates a thrust that produces a counter torque in the airframe 2.

[0047] This counter torque is directed in the opposite direction to the torque exerted by the main rotor 3.

[0048] Therefore, depending on the magnitude of the thrust generated by the torque balance rotor 4, it is possible to direct the helicopter 1 according to a desired yaw angle, or to change the yaw angle according to the maneuver that one wishes to perform.

[0049] Referring to FIGS. 2 to 11, the torque balance rotor 4 basically comprises: - a mast 6 that is rotatable about axis A and is operably connected to the shaft 13 in a known technique; - a plurality of blade plates 8, three in number in the illustrated case, that extend in a cantilever beam manner along respective axes B that cross axis A; - a hub 9 that is externally fastened to a part of the mast 6 and is rotatable integrally with the mast 6 about axis A, to which the blade plates 8 are hinged. Basically, it comprises these components.

[0050] More specifically, the blade plates 8 are - rotatable integrally with the hub 9 and the mast 6 about axis A, and - hinged to the hub 9 so as to be tiltable about respective axes B at the same angle and simultaneously with respect to time in order to change their respective angles of attack. They are hinged to the hub 9.

[0051] Specifically, the hub 9 comprises a plurality of connecting elements 18 projecting radially with respect to the axis A for connection to the respective blade 8. Each blade 8 also comprises a root portion 14 arranged radially inwardly with respect to the axis A and hinge-fixed to the associated connecting element 18 of the hub 9.

[0052] To vary the angle of attack described above, the torque balancing rotor 4 comprises - a flight control 15 (only schematically shown in FIG. 1) operable by the pilot, such as a pedal, and - a control rod 10 sliding parallel to the axis A and operable by the flight control 15 using a mechanical connection or a fly-by-wire method, and - a control element 16 rotatable integrally with the mast 6 about the axis A and connected to the blade 8 in an eccentric manner with respect to the associated axis B, and - a bearing 17 interposed between the control rod 10 and the element 16 and sliding parallel to the axis A integrally with the control rod 10 also comprises.

[0053] More specifically, the mast 6 is hollow.

[0054] The mast 6 comprises - an axial end 20, and - a further open axial end (not shown) opposite the end 20, and - a main portion 22 interposed between the axial end 20 and the further axial end and adapted such that the hub 9 is fitted therein and receives motive power from the shaft 13 (FIG. 1) via the flange 19 also comprises (FIG. 2).

[0055] The control rod 10 is partially housed inside the mast 6.

[0056] The control rod 10 comprises - a first axial end (not shown) connected to the shaft 13, and - a second axial end 24 (FIG. 2) opposite the first axial end and connected to the bearing 17, - A main body 25 passing through an end 20 of the mast 6 and a further axial end is also provided.

[0057] The main body 25, starting from the end 24, successively along the axis A, - A section 26 with a diameter larger than that of the end 24, - A section 27 with a diameter larger than that of the section 26, - A shoulder 28 interposed radially between the sections 26 and 27 is further provided.

[0058] The end 24 is arranged outside the mast 6.

[0059] The first end is operably connected to the flight control unit 15 by a link mechanism (not shown) or by fly-by-wire actuation.

[0060] Element 16 further - A tubular body 40 partially accommodated in the mast 6, connected to the mast 6 in a manner of sliding with respect to the axis A, and partially accommodating the control rod 10, - A flange 42 extending orthogonally to the axis A and fastened to the tubular body 40 at an end opposite to the mast 6, - A plurality of levers 43 hinged to the flange 42 around respective axes C transverse to the axis A and hinged to respective wing plates 8 at eccentric positions with respect to the associated axis B is provided (Figure 2).

[0061] The flange 42 and the bearing 17 are accommodated outside the mast 6 and surround the control rod 10.

[0062] The flange 42 is connected to the mast 6 by a single length-variable bellows joint 44 enabling sliding along the axis A.

[0063] The lever 43 is generally inclined with respect to the axis A and extends from the flange 42 to the end 20.

[0064] The translation of the control rod 10 along the axis A causes the translation of the element 16 via the bearing 17.

[0065] Following the sliding of the element 16 along the axis A, the lever 43 changes their inclination with respect to the axis A at the same mutually identical angle, resulting in the simultaneous rotation of the vane plates 8 at the same mutually equal angle around their respective axes B.

[0066] Specifically, the lever 43 is hinge-fixed to the root portions 14 of the respective vane plates 8.

[0067] The bearing 17 can transmit axial loads parallel to the axis A in both directions.

[0068] In other words, the bearing 17 is configured such that the translation of the control rod 10 in both directions along the axis A causes the translation of the element 16 in the same direction.

[0069] In this way, the bearing 17 connects the control rod 10 and the element 16 in an axially integral and angularly movable manner with respect to the axis A.

[0070] The bearing 17 further includes - a radially outer ring 30 that is rotatable integrally with the element 16, - a radially inner ring 31 that slides integrally with the control rod 10, - a plurality of rolling elements 32, which are ball double rings in the illustrated case, that roll in respective orbits 33 and 34 defined by the respective rings 30 and 31 and is provided with.

[0071] In the illustrated case, the ring 30 has a pair of shoulders 35 and 36 that project radially toward the ring 31 on opposite sides and respectively define axial contact surfaces for the rolling elements 32. The shoulders 35 and 36 define the orbit 33.

[0072] The rolling elements 32 are specifically interposed axially between the shoulders 35 and 36.

[0073] Furthermore, ring 30 is made of two half-rings 41 that are axially in contact with each other as shown.

[0074] Ring 30 is press-fitted at a radially outer position in the tubular body 40 of element 16.

[0075] Ring 31 is interposed axially between shoulders 35 and 36 and has shoulders 37 that project radially toward ring 30. These shoulders 37 are axially interposed between the rolling elements 32 in a plane of symmetry of bearing 17 that is radial with respect to axis A.

[0076] Furthermore, ring 30 is fastened to the tubular body 40 of element 16 on the opposite side of flange 42 in a direction that is radial with respect to axis A.

[0077] Bearing 17 also includes two annular cages 39 that are adapted to keep the rolling elements 32 of the respective rings angularly equidistant from each other.

[0078] Ring 31 is radially inside ring 30 in relation to axis A.

[0079] Specifically, raceway 34 is radially inside raceway 33 in relation to axis A.

[0080] In the following description herein, the term "collapse" of bearing 17 means any effective or initial emergency state where bearing 17 can no longer transmit axial loads from control rod 10 to element 16, i.e., axial translation of element 16 in both directions is caused, and subsequent axial translation of control rod 10 that does not generate a torsional moment on control rod 10 cannot follow.

[0081] Using a non-limiting example, for instance, when foreign matter accidentally enters the bearing 17, or when the rolling elements 32 and / or the raceways 33 and 34 are damaged due to loss of lubricating grease, a first (initial) emergency state occurs.

[0082] In this first emergency state, the ring 31 of the bearing 17 is subjected to a torsional moment.

[0083] Furthermore, the first emergency state of the bearing 17 is generally associated with an increase in the temperature and vibration level in the region around the bearing 17, and / or an increase in the torque transmitted to the ring 31.

[0084] A second emergency state occurs when the rolling element 32 of the bearing 17 breaks in such a way that the control rod 10 can move axially relative to the element 16.

[0085] The torque balance rotor 4 preferably comprises: - a further ring 50 that slides integrally with the control rod 10 along the axis A and is angularly fixed relative to the axis A; - a plurality of rolling elements 51 that are interposed between the rings 31 and 50 and roll in the respective raceways 52 and 53 of the respective rings 31 and 50; - a locking element 55 arranged in a standard configuration that prevents relative rotation between the rings 31 and 50 when the bearing 17 is in its normal operating state. and the locking element 55 is movable from the standard configuration to at least a first or second emergency configuration to allow the ring 31 to rotate freely around the axis A relative to the ring 50 when the bearing 17 is in a defective state.

[0086] Specifically, the rings 30, 31, 50 are coaxial and extend around the axis A.

[0087] Even more precisely, the ring 50 is radially inside the ring 31 in relation to the axis A.

[0088] Furthermore, the orbit 53 is radially inside the orbit 52 with respect to the axis A.

[0089] Specifically, the ring 31 is integrally formed and integrally defines the orbits 34 and 52.

[0090] More specifically, when the bearing 17 is in its normal operating state and the locking element 55 is in its standard configuration, the ring 30 rotates around the axis A, and the rings 31 and 50 are angularly fixed with respect to the axis A.

[0091] In this situation, the ring 50 does not substantially function.

[0092] Conversely, when the bearing 17 is in a defective state and the locking element 55 is in the first or second emergency configuration, the rings 30 and 31 rotate around the axis A, and the ring 50 is angularly fixed with respect to the axis A. In this state, the set of the rings 30 and 31 and the ring 50 form a backup bearing 54 (Figs. 5, 7, 9, and 10), and the backup bearing 54 enables the control of the torque balance rotor 4 even in the defective state of the bearing 17.

[0093] More specifically, the locking element 55 automatically moves from the standard configuration to the first emergency configuration when the temperature of the bearing 17 exceeds its respective threshold value in the event of a defect of the bearing 17.

[0094] The locking element 55 automatically moves from the standard configuration to the second emergency configuration when the vibration in the area of the bearing 17 exceeds its respective threshold value and / or when the torque transmitted from the ring 30 to the ring 31 exceeds its respective threshold value in the event of a defect of the bearing 17.

[0095] The backup bearing 54 can transmit an axial load parallel to the axis A in both directions. In other words, the backup bearing 54 is configured such that the translation of the control rod 10 in both directions along the axis A continues to cause the translation of the element 16 in the same direction even in the event of a defect of the bearing 17.

[0096] The ring 50 is - provided with a radially outer surface 57 that is inclined with respect to the axis A and has two shoulders opposite to each other in the axial direction defining respective raceways 52 and 53, and - a radially inner surface 58 that is opposite to the surface 57 and is press-fitted to the section 26 of the control rod 10. It also has.

[0097] The rolling elements 51 are, in the case shown, tapered rollers with respective side faces converging towards the axis A. Specifically, the tapered rollers are arranged in a cross shape, i.e., with their respective axes converging towards the axis A.

[0098] The backup bearing 54 is adapted to keep the rolling elements 51 of the respective rings angularly equally spaced from each other and further includes two annular cages 59.

[0099] Furthermore, in the case shown, the ring 50 is made of two half rings 45 arranged in contact with each other in the axial direction.

[0100] The locking element 55 is angularly fixed with respect to the axis A in both the standard configuration and the first or second emergency configuration.

[0101] When arranged in the standard configuration, the locking element 55 is axially integrated with the rings 31 and 50, and the control rod 10.

[0102] When arranged in the first or second emergency configuration, the locking element 55 can instead slide parallel to the axis A with respect to the rings 31 and 50 and the control rod 10.

[0103] More specifically, the locking element 55 is - at the insertion position (Figs. 4 and 5) reached when the locking element 55 is in the standard configuration, and - at the withdrawal position (Figs. 6 - 9) reached when the locking element 55 is arranged in the first or second emergency configuration. Rings 31 and 50 are arranged with reference to the axis A.

[0104] The first axial distance between the locking element 55 set at the insertion position and the rings 31 and 50 is smaller than the second axial distance between the locking element 55 set at the withdrawal position and the rings 31 and 50.

[0105] The locking element 55 is arranged on the axial side of the bearing 17 opposite to the mast 6.

[0106] More specifically, the locking element 55 extends annularly around the axis A, - a main body 60, - a ring 65 axially spaced from the main body 60, - a plurality of arms 70 angularly and equally spaced around the axis A and intervening between the main body 60 and the ring 65 and includes (Figs. 3 - 9).

[0107] When the locking element 55 is in the standard configuration (Figs. 4 and 5), - the ring 65 is blocked by interference on the surface 38 of the radially outer ring 31 with respect to the axis A, and, - the arms 70 connect the main body 60 and the ring 65.

[0108] In this standard configuration, the ring 65 prevents the rotation of the ring 31 due to the radial interference between the ring 65 and the surface 38.

[0109] Specifically, the ring 65 is also blocked by the radial interference on the surface 38 by the part axially opposite to the mast 6.

[0110] In the illustrated case, the ring 65 surrounds and contacts the surface 38.

[0111] Referring to FIGS. 6 and 7, when the locking element 55 is in the first emergency configuration, the ring 65 is disengaged from the surface 38 of the ring 31, and thus, the ring 31 will freely rotate about the axis A integrally with the ring 30 under the torsional moment improperly transmitted by the ring 31.

[0112] Referring to FIGS. 8 and 9, when the locking element 55 is in the second emergency configuration, the arm 70 is interrupted and no longer connects the main body 60 and the ring 65. Also in this second emergency configuration of the locking element 55, the ring 31 will freely rotate about the axis A integrally with the ring 30 under the torsional moment improperly transmitted by the ring 31.

[0113] The locking element 55 is made of a material having a first coefficient of thermal expansion, and the rings 50 are made of a material having a second coefficient of thermal expansion smaller than the first coefficient of thermal expansion.

[0114] The first coefficient of thermal expansion is greater than the second coefficient of thermal expansion.

[0115] In the illustrated case, the locking element 55 is made of aluminum, and the rings 30, 31, and 50 are made of steel.

[0116] Therefore, in the event of a temperature rise of the bearing 17 exceeding the threshold due to failure, the ring 65 expands radially so as to be larger than the surface 38 of the ring 50 until it is radially separated from the ring 50.

[0117] When the ring 65 freely separates from the surface 38, the locking element 55 is arranged in the first emergency configuration.

[0118] The arm 70 is dimensioned to break by torsion when the vibration and / or torsional moment transmitted to the ring 31 exceeds the threshold.

[0119] In this method, when the vibration and / or torsional moment transmitted to the ring 31 exceed a threshold value, the locking element 55 moves from the standard configuration to a second emergency configuration (Figs. 8 and 9).

[0120] Furthermore, the arms 70 are angularly and evenly spaced around the axis A and extend parallel to the axis A.

[0121] The main body 60 - A cylindrical portion 62 from which the arm 70 projects axially in a cantilevered manner, - An annular portion 61 that projects radially in a cantilevered manner from the portion 62 in a direction opposite to the axis A and defines the axial end of the main body 60 opposite to the ring 65 also comprises.

[0122] In the illustrated case, the diameter of the main body 60 is equal to the diameter of the ring 65.

[0123] The locking element 55 also comprises a ring 64 that is axially abutted and disposed on the annular portion 61 on the side of the bearing 17 and annularly contacts the main body 60 on the side opposite to the axis A.

[0124] The locking element 55 also comprises a plurality of appendages 75 that extend axially in a cantilevered manner from the main body 60 and are set axially away from the ring 65.

[0125] Each appendage 75 defines an axial slot 76.

[0126] In the illustrated case, the appendage 75 is U-shaped. The appendage 75 also comprises two axial sections 71 that project in a cantilevered manner from the main body 60 and a free connecting section 72 between the arms 71.

[0127] In the illustrated case, the section 72 of the appendage 75 branches with respect to the axis A and extends from each section 71 so as to proceed parallel to the axis A in a direction opposite to the section 71.

[0128] The appendages 75 are angularly and equally spaced from each other.

[0129] The appendages 75 and the arm 70 are different from each other in the circumferential direction.

[0130] The appendages 75 are set to be distinguishable from the ring 65 in the axial direction.

[0131] In the illustrated case, the ring 65 is disposed axially between the main body 60 and the rolling element 32.

[0132] The torque balancing rotor 4 is - Fixed angularly with respect to the axis A and connected to the ring 80 connected to the ring 50 by a plurality of axially extending pins 82, which are angularly and equally spaced from each other due to reasons such as angularity and slide axially integrally with the ring 50, the bearing 17, and the control rod 10. In the illustrated case, there are six such pins. - A ring 85 that is fixed angularly with respect to the axis A and slides axially integrally with the ring 50, the bearing 17, and the control rod 10. - Engaging with respective slots 76 with axial play, fastened to the ring 80, and arranged in axial contact with the ring 85. In the illustrated case, there are four such radially extending pins 81. and also includes.

[0133] In the illustrated case, a portion 62 of the main body 60 is interposed radially between the rings 80 and 85.

[0134] Referring to FIGS. 3 to 9, the ring 80 is fastened to the section 26 of the main body 25, and these are interposed axially between the nut 29 screwed into the end 24 of the control rod 10 and the shoulder 28 of the control rod 10.

[0135] When arranged in the first or second emergency configuration (Figs. 6 - 9), the locking element 55 can slide along the axis A with respect to the rings 85, 80, 31, and 30 and the control rod 10. This occurs because the respective slots 76 with axial play engage with the pins 81.

[0136] When the locking element 55 is in the standard configuration (Figs. 4 and 5), the pins 81 are axially abutted and arranged at the respective axial ends 77 of the corresponding slots 76 located on the opposite side of the bearing 17 (Fig. 5).

[0137] Conversely, when arranged in the first or second emergency configuration (Figs. 6 - 9), the locking element 55 can slide to the withdrawn position, where the pins 81 are abutted and arranged at the respective axial ends 78 located on the side of the bearing 17, opposite to the ends 77 of the corresponding slots 76 (Fig. 7).

[0138] The torque balancing rotor 4 also includes a spring 100 interposed between the ring 50 and the locking element 55.

[0139] The spring 100 is oriented parallel to the axis A and is configured to exert an elastic force on the locking element 55 oriented from the opposite side of the bearing 17. This force elastically pre - loads the locking element 55 towards the withdrawn position in Figs. 6 - 9.

[0140] This elastic force is counteracted by an opposing axial frictional force resulting from the radial interference between the ring 65 and the surface 38 reached in the standard configuration when the locking element 55 is in the inserted position (Figs. 4 and 5).

[0141] When arranged in this first or second emergency configuration, the locking element 55 is axially pushed by the spring 100 from the side opposite to the bearing 17 until it reaches the withdrawn position (Figs. 6 - 9).

[0142] Reaching this withdrawn position indicates a defective state of the bearing 17.

[0143] More specifically, the spring 100 is interposed between a ring 64 integral with the locking element 55 and a ring 85 in contact with the pin 81.

[0144] When shown in the drawings, the spring 100 is a wave spring.

[0145] Specifically, the spring 100 includes two axially cooperating annularly extending wave elements.

[0146] Referring to FIG. 2, the torque balance rotor 4 also includes a cover element 46 that is fastened to the flange 42 and as a result is rotatable about the axis A with the element 16.

[0147] The cover 46 is symmetric with respect to the axis A and defines a cavity 47 that houses the main body 60, the spring 100, the nut 29, the pin 81, and the rings 80 and 85.

[0148] Preferably, the cover 46 is made of a transparent material and is visible from the outside of the helicopter 1.

[0149] The cover 46 is rotatable about the axis A integrally with the control element 16.

[0150] The locking element 55 preferably also includes a colored annular band (not shown in the attached drawings).

[0151] This annular band is visible from the outside through the cover 46 when the locking element 55 is in the withdrawn position so as to provide a quick indication of the fact that the locking element 55 is in the withdrawn position.

[0152] Conversely, this annular band cannot be seen from the outside through the cover 46 when the locking element 55 is in the inserted position.

[0153] Referring to FIGS. 5, 7, and 9, the shoulder 37 of the bearing 17 is set radially away from the ring 30.

[0154] The outer diameter of the shoulder 37 is larger than the inner diameters of the raceways 33 and 34.

[0155] For this reason, in the event of a bearing 17 defect that results in the destruction of the rolling elements 32, the translation of the control rod 10 towards the raceway 33 causes the shoulder 37 to abut against the raceway 33.

[0156] Similarly, the translation of the control rod 10 towards the raceway 34 causes the shoulder 37 to abut against the raceway 34.

[0157] The state of contact of the shoulder 37 with the raceways 33 and 34 in the axial direction can be made to slide again along the axis A integrally with the ring 30 by the set formed by the control rod 10 and the rings 31 and 50, thereby ensuring that the controllability of the torque balance rotor 4 is not lost.

[0158] Furthermore, the shoulder 37 is set axially apart from the cage 39 of the rolling elements 32.

[0159] The bearing 17 also includes an annular insert 93 interposed axially between the half-rings 41 and disposed on the radially outer surface of the ring 30.

[0160] The backup bearing 54 also includes an annular insert 94 interposed between the half-rings 45 and disposed on the radially inner surface 58 of the ring 50.

[0161] The operation of the torque balance rotor 4 starts from the state where the bearing 17 functions correctly and the locking element 55 is arranged in the standard configuration and insertion position (Figs. 2, 4, and 5), and is described hereinafter.

[0162] In this state, the operation of the flight control unit 15 causes the translation of the control rod 10 in a given direction along the axis A.

[0163] This translation causes the integral translation of the bearing 17 and the element 16 along the axis A.

[0164] As a result, the element 16 moves away from (or approaches) the vane 8, changing the inclination of the lever 43 with respect to the axis B and increasing (or decreasing) the angle of attack of the vane 8.

[0165] This movement of the lever 43 results in a simultaneous rotation of the vane 8 at an equal angle around the associated axis B, resulting in an adjustment of the angle of attack of the vane 8.

[0166] The bearing 17 enables the rotation of the element 16 with respect to the control rod 10 around the axis A.

[0167] More specifically, the ring 30 rotates integrally with the element 16 around the axis A, while the rings 31 and 50 remain fixed with respect to the axis A.

[0168] This occurs because the ring 65 is pressed against the ring 31 by a radial interference, preventing the rotation of the ring 31 and, consequently, also preventing the rotation of the ring 50.

[0169] The axial frictional force generated by the interference assembly is greater than the elastic force applied to the locking element 55 by the spring 100.

[0170] In this state, the ring 50 and, consequently, the backup bearing 54 do not substantially function.

[0171] In the event of a bearing 17 failure that results in an increase in temperature above the respective threshold values in the region of the bearing 17, the radial thermal expansion of the ring 65 is greater than the thermal expansion of the ring 31.

[0172] As a result, the locking element 55 moves to a first emergency configuration (Figures 6 and 7) in which the ring 65 is set away from the ring 31.

[0173] Thus, the ring 31 can rotate around the axis A with respect to the ring 50, and the ring 50 remains angularly fixed around the axis A because it is blocked by the control rod 10 instead.

[0174] In this state, the ring 31 and the bearing 17 do not substantially function, and the rotation of the element 16 relative to the control rod 10 around the axis A is enabled by the backup bearing 54.

[0175] In the event of an increase in the torque transmitted from the ring 31 to the ring 30 and / or a defect event of the bearing 17 that results in vibration in the area of the bearing 17 exceeding the threshold value, a torsional breakage of the arm 70 is induced.

[0176] This breakage causes the locking element 55 to assume a second emergency configuration (Figs. 8 and 9).

[0177] Thus, similar to the first emergency configuration, the ring 31 can rotate around the axis A relative to the ring 50, while the ring 50 remains angularly fixed around the axis A instead.

[0178] Furthermore, the ring 31 and the bearing 17 do not substantially function, and the rotation of the element 16 relative to the control rod 10 around the axis A is enabled by the backup bearing 54.

[0179] When set in the first or second configuration, the locking element 55 is pushed by the spring 100 towards the extraction position (Figs. 6 - 9).

[0180] This sliding results in the movement of the slot 76 relative to the pin 81 and the movement of the ring 85.

[0181] In the extraction position, the annular band of the locking element 55 is visible from the outside of the helicopter 1, visually guiding the pilot or inspection engineer that the bearing 17 is in an initial or effective defective state.

[0182] In the event of a defect of the bearing 17 that causes the destruction of the rolling element 32, the translation of the control rod 10 towards the raceway 33 (34) causes the shoulder 37 to abut against the raceway (34), maintaining two - way axial contact between the control rod 10 and the bearing 17, thereby ensuring the controllability of the torque - balancing rotor 4.

[0183] Referring to FIGS. 12 and 13, reference numeral 4' indicates a torque balancing rotor according to a second embodiment of the present invention.

[0184] The rotor 4' is similar to the rotor 4, and the differences from the rotor 4 are only described below. The same or equivalent parts of the rotors 4 and 4' are marked with the same reference numerals whenever possible.

[0185] The rotor 4' is different from the rotor 4 in that it does not have a shoulder 37.

[0186] Furthermore, the rotor 4' is different from the rotor 4 in that a pair of blocking elements 90' is interposed axially between the shoulders 35 and 36.

[0187] The rotor 4' is also different from the rotor 4 in that the surface 38' has a pair of expansion and contraction portions 99' interposed axially between the rolling elements 32.

[0188] The expansion and contraction portions 99' are continuous axially and converge symmetrically towards each other on the opposite side of the axis A with respect to the remaining portions of the respective surfaces 38'.

[0189] The expansion and contraction portions 99' are planar so as to define an inverted V shape towards the blocking elements 90'.

[0190] The blocking element 90' is fixed to the ring 30.

[0191] In a normal configuration, the bearing 17 does not permit axial movement between the rings 30 and 31.

[0192] In this normal configuration, the blocking element 90' rotates integrally with the ring 30 relative to the ring 31.

[0193] Furthermore, the blocking elements 90' are separated from each other by the respective expansion and contraction portions 99' using the respective clearances 108'.

[0194] What is different is that in the event of damage to the raceways 33, 34 of the rolling elements 32, which is a phenomenon technically known as "spalling", a specific axial movement is permitted between the rings 30, 31.

[0195] In this state, the blocking elements 90' come into contact and engage with their respective surfaces 99', thereby substantially reducing or even substantially preventing wear between the rings 30, 31.

[0196] More specifically, the blocking elements 90' are interposed axially between the rolling elements 32.

[0197] Each blocking element 90' has a respective tapered radially inner surface 101' with respect to the axis A.

[0198] Furthermore, each blocking element 90' is bounded by a respective radially outer surface 102' that is radially opposite to its respective inner surface 101' with respect to the axis A.

[0199] The size of the surface 101' parallel to the axis is larger than the surface 102' parallel to the axis A.

[0200] Each element 90' extends between its respective surfaces 101', 102' and is further bounded by respective radial surfaces 103' that are in contact with the surfaces 101', 102'.

[0201] Each element 90' - a respective main body 105' that defines the surfaces 101', 102', 103', - respective radial shoulders 106' that project from the body 105' and are bounded by the surfaces 102', 103', - further respective radial shoulders 107' that project from the body 105', are axially spaced from their respective shoulders 106', and bound the blocking element 90' on the axially opposite side with respect to their respective surfaces 103' and also comprises.

[0202] The radial size of the shoulder 106' associated with the shaft A is larger than the radial size of the shoulder 107' associated with the shaft A.

[0203] The shoulder 106' of each blocking element 90' is axially interposed between the respective shoulder 107' and the surface 103'.

[0204] The blocking elements 90' themselves, the respective clearances 108' themselves, and the respective surfaces 101' are symmetrically arranged with respect to a plane orthogonal to the shaft A.

[0205] Specifically, the surfaces 103' of the respective elements 90' are in contact with each other in the axial direction parallel to the shaft A and are located in a plane orthogonal to the shaft A.

[0206] The surfaces 101' branch symmetrically from each other starting from the respective surfaces 103' toward the shaft A and proceed toward the respective shoulders 107'.

[0207] The clearances 108' branch from each other starting from the respective surfaces 103' toward the respective shoulders 107'.

[0208] The shoulders 106' and 107' contact the respective half-ring 41 of the ring 30.

[0209] Even more precisely, the shoulder 106' is axially interposed between the half-rings 41.

[0210] The shoulder 107' is in radial contact with the radially inner surface 109' of the respective half-ring 41.

[0211] The operation of the rotor 4' is different from the operation of the rotor 4 in that when the bearing 17 operates correctly and the locking element 55 is in the standard configuration and insertion position, the blocking element 90' rotates around the shaft A with respect to the ring 31 stationary with the ring 30 and is separated from the relative expansion and contraction portion 99' using the relative clearance 108'.

[0212] In this state, the bearing 17 substantially prevents axial movement between the rings 30 and 31.

[0213] What is different is that in the event of a bearing 17 failure due to damage to the raceways 33 and 34 of the rolling elements 32, which is a phenomenon technically known as "skidding", a specific axial movement can be allowed between the rings 30 and 31.

[0214] However, in this state, the blocking element 90' blocks against the relative expansion and contraction part 99' of the ring 31, thus preventing this axial movement and preventing the resulting wear, heat generation, and potential damage to the rings 30 and 31.

[0215] Specifically, the axial displacement of the ring 31 is caused by the movement of the control rod 10 by the act of the pilot.

[0216] Referring to FIGS. 14 to 17, the reference numeral 4'' indicates a torque balance rotor according to the third embodiment of the present invention.

[0217] The rotor 4'' is similar to the rotor 4, and only the differences from the rotor 4 are described below. The same or equivalent parts of the rotors 4 and 4'' are marked with the same reference numerals whenever possible.

[0218] The rotor 4'' is different from the rotor 4 in that the rings 50'', 31'' and the rolling elements 51'' form a bearing 17''.

[0219] What is different is that the rings 31'', 30'' and the rolling elements 32'' form a backup bearing 54''.

[0220] In the illustrated embodiment, the rolling elements 51'' roll in the respective raceways 52'' and 53'' of the respective rings 31'' and 50''. Further, the rolling elements 51'' form two axially spaced rings of tapered rollers.

[0221] In the illustrated embodiment, the rolling elements 51'' are axially preloaded and are tapered rollers.

[0222] The rolling elements 32'' roll in respective raceways 33'', 34'' of respective rings 30'', 31''. In the illustrated embodiment, the rolling elements 32'' form two axially spaced rings of tapered rollers.

[0223] In the illustrated embodiment, the rolling elements 32'' are axially preloaded and are interposed axially between the rolling elements 51''.

[0224] The radially outer surface 57'' of the ring 50'' comprises a pair of telescoping portions 98'' that define respective raceways 53'', and a pair of telescoping portions 99'' that are interposed axially between the telescoping portions 98''.

[0225] The telescoping portions 99'' are continuous axially and converge symmetrically towards each other on the side of the axis A with respect to the remainder of the surface 57''.

[0226] The telescoping portions 99'' are planar so as to define an inverted V-shape.

[0227] The ring 31'' further comprises - a central body 120'', and - a pair of lateral projections 101'' that are axially opposite the other and project laterally from respective opposite axial sides of the body 120'' and.

[0228] The body 120'' converges towards each other on the side of the axis A and is bounded by a pair of radially inner surfaces 103'' that face respective telescoping portions 99''.

[0229] Specifically, the surface 103'' is radially outside with respect to the relative telescoping portion 99''.

[0230] When the 17'' bearing operates correctly and the locking element 55'' is in its standard configuration and insertion position, the surface 103'' is separated from the respective expansion and contraction portions 99'' of the ring 50'' by the respective clearances 108''.

[0231] The surface 103'', the clearance 108'', and the expansion and contraction portion 99'' extend symmetrically with respect to a plane orthogonal to the axis A.

[0232] What is different is that in the event of bearing 17'' failure due to damage to the raceways 52'', 53'' of the rolling elements 51'', which is a phenomenon technically known as "spalling", a specific axial movement can be tolerated between the rings 50'', 31''.

[0233] However, in this state, the surface 103'' axially blocks against the relative expansion and contraction portion 99'' of the ring 31'', thus preventing this axial movement and the resulting wear, heat generation, and potential damage to the rings 50'', 31''.

[0234] The protrusions 101'' define the respective raceways 34'' on their respective radially outer surfaces and the respective raceways 52'' on their respective radially inner surfaces.

[0235] The rotor 4'' is different from the rotor 4 in that when arranged in the standard configuration and insertion position shown in FIGS. 14 and 16, when the bearing 17'' is in its normal operating state, the locking element 55'' prevents relative rotation between the rings 30'', 31'' and allows relative rotation between the assembly formed by the rings 30'', 31'' and the stationary ring 50''.

[0236] In this state, the ring 50'' is angularly stationary with respect to the axis A, while the rings 31'', 30'' rotate around the axis A.

[0237] In such a state, the rotation between the rings 50'' and 30'', 31'' can be lubricated by grease.

[0238] Furthermore, when the locking element 55'' is arranged and set in the withdrawal position shown in FIGS. 15 and 17 in the first or second emergency configuration, when the bearing 17'' is in a defective state, the rings 31'', 50'' are made integral with each other around the shaft A, and the rotation of the ring 30'' around the shaft A with respect to the stationary assembly formed by the rings 31'', 50'' is allowed.

[0239] Therefore, when the bearing 17'' is in a defective state, while the rings 50'', 31'' are angularly stationary with respect to the shaft A, the ring 30'' rotates around the shaft A.

[0240] In this state, the rings 31'', 30'' define a backup bearing 54''.

[0241] The locking element 55'' is different from the locking element 55 for rotating integrally around the shaft A together with the spring 100 and the cover 46.

[0242] Specifically, the locking element 55'' is similar to the pin 81, rotates integrally with the cover 46, and includes a plurality of pins 81'' that respectively engage with axially play-provided slots 76'' similar to the slot 76 that rotates integrally with the cover 46.

[0243] The rotor 4'' - a tank 150'' filled with a lubricant fluid, - a frangible element 151'' that bounds the tank 150'' on the side of the rings 30'', 31'', 50'', - a plurality of punching elements 152'' carried by the locking element 55'' is advantageously provided, and thus is further different from the rotor 4, The punching element 152'' is spaced apart from the frangible element 151'' when the locking element 55'' is in the insertion position (FIGS. 14 and 16), and punches the frangible element 151'' when the locking element 55'' is in the withdrawal position (FIGS. 15 and 17).

[0244] The breakable element 151'' fluidly isolates the tank 150'' and the rolling element 32'' when the locking element 55'' is in the inserted position (Figs. 14 and 16), and fluidly connects the tank 150'' and the rolling element 32'' when the locking element 55'' is in the withdrawn position (Figs. 15 and 17).

[0245] Specifically, the tank 150'' is defined by the cover 46 and extends annularly around the axis A.

[0246] The breakable element 151'' extends parallel to the axis A and closes the tank 150'' on the opposite side of the cover 46 when the locking element 55'' is in the inserted position.

[0247] In the illustrated embodiment, the breakable element 151'' is preferably a disc-shaped membrane made of aluminum.

[0248] The punching element 152'' projects from the body 60 of the locking element 55'' on the axially opposite side with respect to the ring 65.

[0249] In the illustrated embodiment, the punching elements 152'' are angularly spaced around the axis A.

[0250] As shown in Fig. 15, the punching element 152'' is shaped as a relative lance with a sharp tip converging and formed to proceed from the body 60 towards the breakable element 151''.

[0251] Preferably, the punching element 152'' is radially outside with respect to the element 65 and defines the radially outer periphery of the element 55''.

[0252] In the illustrated embodiment, the body 60 and the punching element 152'' are made of titanium.

[0253] The ring 65 and the arm 70 are made of aluminum in the illustrated embodiment.

[0254] When the locking element 55'' is in the withdrawn position shown in FIG. 17, the rotor 4'' defines a fluid path 170'' from the tank 150'' to the region 160'' surrounding the rolling elements 32''.

[0255] Specifically, the region 160'' is bounded radially between the rings 30'', 31''.

[0256] The region 160'' is axially bounded between the shoulders 35, 36 on the radially opposite side of the axis A and between the projections 101'' on the side of the axis A.

[0257] Referring to FIG. 17, the fluid path 170'' extends circumferentially around the rotor 4''. Further, the path 170'' includes a plurality of through openings 171'' that extend axially through the broken element 152'', the passage 175'' between the rings 65, 31'', and the passage 176'' between the rings 31'', 30''.

[0258] What is different is that when the locking element 55'' is in the withdrawn position shown in FIG. 17, the fluid path 170'' is blocked by the breakable element 151''.

[0259] The rotor 4'' is disposed on the axially opposite side of the rolling elements 32'' with respect to the breakable element 151'', and also includes a labyrinth seal 180'' adapted to tightly close the fluid path 170'' and keep the lubricant fluid in continuous contact with the rolling elements 32'' when the locking element 55'' is in the withdrawn position.

[0260] Specifically, the labyrinth seal 180'' includes - a seal 181'' interposed radially between the rings 50'', 31'' on the axially opposite side with respect to the element 55'', and - a seal 182'' interposed radially between the rings 50'', 30'' on the axially opposite side of the seal 181'' with respect to the rolling elements 32'' comprising (FIG. 17).

[0261] Specifically, the seals 181'', 182'' are formed as annular bands. In the illustrated embodiment, the seal 182'' has a larger radial dimension than the seal 181''.

[0262] The operation of the rotor 4'' differs from that of the rotor 4 in that, thanks to the connection between the pins and the respective slots, the locking element 55'' rotates integrally with the cover 46 and the ring 30'' about the axis A.

[0263] When the locking element 55'' is in the insertion position and the standard configuration shown in FIGS. 14 and 16, the bearing 17'' formed by the rings 50'', 31'' and the rolling elements 51'' enables the rotation of the element 16 about the axis A with respect to the rod 10.

[0264] More specifically, the ring 50'' is stationary about the axis A, and the rings 31'', 30'' rotate integrally about the axis A. In this state, the locking element 55'' is in contact with the ring 31'' and is angularly integral with the ring 31''.

[0265] Furthermore, the backup bearing 54'' does not substantially function.

[0266] The punching element 152'' is spaced apart from the frangible element 151'' which has not yet been broken.

[0267] Therefore, the lubricant fluid remains in the tank 150''.

[0268] In the event of a bearing 17'' failure event that results in an increase in the temperature of the bearing 17'' above a threshold value, or an increase in the torque transmitted from the ring 31'' to the ring 50'', and / or an increase in the vibration in the region of the bearing 17'' above the respective values, the locking element 55'' is displaced to the first or second emergency configuration shown in FIGS. 15 and 17.

[0269] Therefore, the spring 100 displaces the locking element 55'' to the withdrawal position shown in FIGS. 15 and 17.

[0270] In this state, the ring 31'' remains angularly stationary, and the rolling elements 32'' permit rotation of the ring 30'' relative to the ring 31'' about the axis A.

[0271] Furthermore, the punching element 152'' destroys the breakable element 151''. In this way, the lubricant fluid contained in the tank 150'' can flow from the tank 150'' to the region 160'' along the fluid path 170'', ensuring continuous lubrication of the rolling elements 32''.

[0272] More precisely, the lubricant fluid flows through the passage 171'' passing through the destroyed breakable element 151'' and the passage 172'' between the rings 65, 31''.

[0273] The locking element 55'', the cover 46, and the rings 31'', 30'' generate a lubricant fluid bath (shown in gray in FIG. 17) in the peripheral region of the rotor 4'' where the rolling elements 32'' are disposed due to centrifugal action, as shown in FIG. 17.

[0274] The labyrinth seal 180'' is effective in containing the lubricant fluid in the region 160''.

[0275] Regardless of the configuration of the locking element 55'', the normal blocking surface 103'' rotates about the axis A together with the ring 31'' relative to the stationary ring 50'', and is spaced apart from the relative expansion and contraction portion 99'' using the relative clearance 108''.

[0276] In this state, the bearing 17'' substantially prevents axial movement between the rings 50'', 31''.

[0277] What is different is that, technically, in the event of bearing 17'' failure due to damage to the orbits 53'' and 52'' of the rolling elements 51'', a specific axial movement can be allowed between the rings 50'' and 31''.

[0278] However, in this state, the surface 103'' of the ring 31'' axially blocks against the relative expansion and contraction part 99'' of the ring 50'', thus preventing this axial movement and the resulting wear, heat generation, and potential damage to the rings 50'' and 31''.

[0279] From an examination of the characteristics of the torque balancing rotors 4, 4', 4'' according to the present invention, the advantages that can be achieved thereby are clear.

[0280] More specifically, the locking element 55 prevents the relative rotation of the rings 31 and 50 in the standard configuration (Figs. 4 and 5), and allows the rotation of the ring 31 relative to the ring 50 in the first and second emergency configurations (Figs. 6 - 9) when the bearing 17 is in an initial or effective failure.

[0281] In this way, even in the event of an initial or effective failure that causes seizure of the bearing 17 in some cases, the rings 30 and 31 can rotate integrally with each other relative to the ring 50 so as not to lose the ability to adjust the angle of attack of the vane 8 via the control rod 10. In other words, in the event of failure, the bearing 17 does not function and the backup bearing 54 automatically functions.

[0282] More specifically, in the case of a temperature rise in the region of the bearing 17, the locking element 55 moves from the standard configuration to the first emergency configuration.

[0283] More clearly, by having a larger coefficient of thermal expansion, the ring 65 disengages from the surface 38 of the ring 31 which has a smaller coefficient of thermal expansion.

[0284] When the torque acting on the ring 31 or the vibration in the region of the bearing 17 exceeds the respective threshold value, the locking element 55 moves from the standard configuration to the second emergency configuration.

[0285] More specifically, the arm 70 breaks by torsion.

[0286] In this way, the rings 31 and 30 rotate relative to the ring 50 when the temperature in the region of the bearing 17 exceeds the respective threshold value and / or when the torque acting on the ring 31 inappropriately or the vibration in the region of the bearing 17 exceeds the respective threshold value.

[0287] Furthermore, the locking element 55 is arranged in the withdrawal position when reaching the first or second standard configuration.

[0288] In this way, it is possible to recognize the initial or effective state of the defect of the bearing 17 based only on the axial position of the locking element 55 relative to the control rod 10.

[0289] The spring 100 elastically preloads the locking element 55 towards the withdrawal position, which advantageously acts to quickly reach this position.

[0290] When the locking element 55 is in the withdrawal position, the band is visible through the cover 46, which is transparent to the crew and / or inspection technicians from the outside of the helicopter 1, thereby providing a clear and rapid indication that the bearing 17 is in a defective state.

[0291] The shoulder 37 has an outer diameter larger than the raceways 33 and 34 of the bearing 17.

[0292] For this reason, in the event of a defect of the bearing 17 that causes the destruction of the rolling elements 32, the translation of the control rod 10 towards the raceway 33 or 34 brings the shoulder 37 into contact with the raceway 33 or 34, so as not to lose the controllability of the torque balance rotors 4, 4'.

[0293] The rotor 4′ (Figs. 12 and 13) is carried by the ring 30 and further comprises a pair of blocking elements 90′ provided with respective tapered surfaces 101′.

[0294] The surfaces 101′ are spaced apart from the respective telescopic portions 99′ of the ring 31 when the bearing 17 is in its normal operating state.

[0295] The difference is that the surface 101′ blocks the blocking element 90′ integral with the ring 30 against the respective telescopic portions 99′ of the ring 31 in the event of a bearing 17 failure due to damage to the raceways 33, 34 of the rolling elements 32.

[0296] In this way, even when the raceways 33, 34 are damaged, relative axial movement between the rings 30, 31 is substantially prevented.

[0297] Accordingly, the risk of wear, heat generation, and resulting damage to the rings 30, 31 is substantially avoided.

[0298] The locking element 55′′ of the rotor 4′′ allows relative rotation of the ring 31′′ with respect to the ring 50′′ in the standard configuration (Figs. 14 and 16) and allows relative rotation of the ring 30′′ with respect to the ring 31′′ in the first and second emergency configurations (Figs. 15 - 17) when the bearing 17′′ is in an initial or effective failure.

[0299] In this way, the locking element 55′′ of the rotor 4′′ achieves substantially the same advantages as the locking element 55 of the rotor 4.

[0300] Furthermore, the locking element 55′′ comprises a plurality of punching elements 152′′ that destroy the breakable element 151′′ when the locking element 55′′ is set in the pulled - out position and in the event of a bearing 17′′ failure.

[0301] In this method, the lubricant fluid contained in the tank 150'' can flow along the fluid circuit 170'' towards the rolling elements 32'', ensuring the proper operation of the rolling elements 32'' of the backup bearing 54''.

[0302] The rotation of the cover 46, locking element 55'', and ring 30'' around the axis A propels the lubricant fluid towards the rolling elements 32'' located radially outside the rolling elements 51'' due to the centrifugal action.

[0303] In this method, the centrifugal action generates a lubricant fluid bath in the surrounding area of the rotor 4'' where the rolling elements 32'' and the region 160'' are located.

[0304] The labyrinth seal 180'' is effective in containing the lubricant fluid in the region 160''.

[0305] Similar to the rotor 4, the surfaces 103'' of the ring 31'' are spaced apart from the respective expansion / contraction portions 99'' of the ring 30'' when the bearing 17'' is in its normal operating state.

[0306] The difference is that the surface 103'' blocks against the respective expansion / contraction portions 99'' in the event of bearing 17'' failure due to damage to the raceways 52, 53 of the rolling elements 51''.

[0307] In this method, even when the raceways 52, 53 of the rolling elements 51'' are damaged, the axial relative movement between the rings 50'', 31'' is substantially prevented.

[0308] Therefore, the risk of wear, heat generation, and resulting damage to the rings 50'', 31'' is substantially avoided.

[0309] The rings 30, 30''; 31, 31''; 50, 50'' of the rotors 4, 4'', 4'' are coaxial and extend around the common axis A.

[0310] More precisely, rings 50, 50'' are radially inside rings 31, 31'', and rings 31, 31'' are further radially inside rings 30, 30''.

[0311] Therefore, the bearings 17, 17''; 54, 54'' of the rotors 4, 4', 4'' are particularly compact in the radial direction of the shaft A compared to the solutions shown in U.S. Patent No. 9,359,073(B) and considered in the introduction of this description.

[0312] In this way, the tracks 52'', 53'', 33'', 34'' can be coaxially mounted inside the rotors 4, 4', 4'' with a very limited axial size, thus substantially eliminating the need for a redesign of the rotors 4, 4'' different from the solution shown in U.S. Patent No. 9,359,073(B).

[0313] Furthermore, the tracks 52'', 53'', 33'', 34'' are defined by only three rings 30, 30''; 31, 31''; 50, 50'' instead of the four rings disclosed in U.S. Patent No. 9,359,073(B).

[0314] By coaxializing the rings 30, 30''; 31, 31''; 50, 50'', the bearings 17, 17''; 54, 54'' can transmit translational loads along a first direction parallel to the shaft A and second and third directions orthogonal to the shaft A, and can transmit rotational loads around the second and third directions.

[0315] The difference is that the bearings disclosed in U.S. Patent No. 9,359,073(B) are effective in transmitting only axial loads parallel to the rotational direction of the mast.

[0316] Furthermore, the bearings 17, 17''; 54, 54'' comprise two rings of rolling elements 32, 32''; 51, 51''.

[0317] In this method, the rolling elements 32, 32''; 51, 51'' can be easily preloaded axially, and thus, axial play, as well as the resulting vibrations and noises, can be strongly suppressed.

[0318] The rolling elements 51, 51'' are tapered rollers. In this method, the bearings 17, 17''; 54, 54'' are not substantially exposed to the mechanism of false Brinell damage.

[0319] Finally, it is obvious that improvements and modifications can be made to the torque balancing rotors 4, 4', 4'' described and illustrated herein without departing from the scope defined by the claims.

[0320] Specifically, the ring 50 may be arranged radially outside the ring 30.

[0321] Furthermore, the locking element 55 may include a plurality of radial pins interposed between the ring 65 and the surface 38. These pins are breakable when the torque transmitted from the ring 30 to the ring 31 and / or the vibrations in the region of the bearing 17 exceed their respective thresholds. These pins may also be made of a material having a particularly low torsional resistance exceeding the threshold.

[0322] The locking element 55 may include a brazing between the rings 31 and 50 sized to allow rotation between the rings 31 and 50 when the torque transmitted from the ring 30 or the vibrations in the region of the bearing 17 exceed their respective thresholds. Furthermore, the brazing is performed using a material that allows rotation of the ring 31 relative to the ring 50 when a temperature threshold is exceeded.

[0323] The rolling elements 32, 32'' and 51, 51'' may be needle rollers, spherical rollers, self-aligning ball bearings, or sliding ball bearings.

[0324] The rolling elements 32, 32'' and 51, 51'' may have an "O-shaped" (back-to-back) arrangement instead of an "X-shaped" (opposite) arrangement.

Description of Symbols

[0325] 1 Helicopter 2 Airframe 3 Main Rotor 4, 4′, 4′′ Torque Balance Rotor 5 Turbine 6 Mast 8 Flap 9 Hub 10 Control Rod 12 Gear Train 13 Shaft 14 Root 15 Flight Control Unit 16 Control Element 17, 17′′ Bearing 18 Connecting Element 19 Flange 20 Axial End 22 Main Part 24 Second Axial End 25 Main Body 26, 27 Section 28 Shoulder 29 Nut 30, 30′′ Radial Outer Ring 31, 31′′ Radial Inner Ring 32, 32′′ Rolling Element 33, 33′′, 34, 34′′ Race 35, 36 Shoulder 37 Shoulder 38, 38′ Ring Surface 39 Annular Cage 40 Tubular Body 41 Half Ring 42 Flange 43 Lever 44 Length-Variable Bellows Joint 45 Half Ring 46 Cover Element 47 Cavity 50, 50′′ Ring 51, 51′′ Rolling Element 52, 52′′, 53, 53′′ Race 54, 54'' backup bearings 55, 55'' locking elements 57, 57'' radially outer surfaces 58 radially inner surface 59 annular cage 60 main body 61 ring portion 62 cylindrical portion 64, 65 rings 70 arm 71 axial section, arm 72 freely connected section 75 appendage 76, 76'' axial slots 77, 78 axial ends 80 ring 81, 81'' pins 82 axial pin 85 ring 90' blocking element 93, 94 annular inserts 99' telescopic part 99' telescopic part, surface 99'' telescopic part 100 spring 101' radially inner surface, tapered surface 101'' protrusion 102' radially outer surface 103' radial surface 103'' radially inner surface, normal blocking surface 105' main body 106' radial shoulder 107' radial shoulder 108', 108'' clearances 109' inner surface 120'' central body 150'' tank 151'' frangible element 152'' punched element 160'' region surrounding rolling element 32'' 170'' fluid path, fluid circuit 171'' through opening, passage 172'' Passageway 175'' and 176'' Passageways 180'' Labyrinth Seal 181'' Seal 182'' Seal Axes A, B, and C

Claims

1. A torque balancing rotor (4; 4′; 4′′) for a helicopter (1), comprising: - a mast (6) rotatable about a first axis (A); - a plurality of blade plates (8) hingedly fixed to the mast (6) and extending along respective second axes (B) transverse to the first axis (A), each blade plate (8) being rotatable about its respective second axis (B) to vary its respective angle of attack; - an element (16) sliding along the first axis (A) relative to the mast (6) and rotating integrally with the mast (6), the element (16) being operatively connected to the blade plates (8) to effect rotation of the blade plates (8) about their respective second axes (B) following translation of the element (16) along the first axis (A); - a control rod (10) sliding axially along the first axis (A) relative to the mast (6) and angularly fixed relative to the first axis (A); - a first ring (30; 30′′) rotatable integrally with the element (16) about the first axis (A); - a second ring (50; 50′′) sliding integrally with the control rod (10) along the first axis (A) and angularly fixed relative to the first axis (A); - a third ring (31; 31′′); - a plurality of first rolling elements (32; 32′′) interposed between the first and third rings (30, 31; 30′′, 31′′) and adapted to roll in respective first tracks (33, 34; 33′′, 34′′) of the first and third rings (30, 31; 30′′, 31′′); - a plurality of second rolling elements (51; 51′′) interposed between the second and third rings (50, 31; 50′′, 31′′) and adapted to roll in respective second tracks (52, 53; 52′′, 53′′) of the second and third rings (50, 31; 50′′, 31′′); - a locking element (55; 55′′) arranged in a standard configuration and permitting relative rotation between the third ring (31; 31′′) and the other one (50; 30′′) of the first and second rings (30, 50; 30′′, 50′′); characterized by the above. The locking element (55; 55'') is movable from the standard configuration to at least one first or second emergency configuration, preventing relative rotation between the third ring (31; 31'') and the other one (30; 50'') of the first ring and the second ring (30, 50; 30'', 50''), and permitting relative rotation between the third ring (31; 31'') and one of the first ring and the second ring (50; 30''), The first ring (30; 30''), the third ring (31; 31''), and the second ring (50; 50'') are coaxial and extend around the first axis (A), The second ring (50; 50'') is radially inside the third ring (31; 31''), The third ring (31; 31'') is radially inside the first ring (30; 30''), The third ring (31; 31'') is an integral part and defines one of the second tracks (52, 53; 52'', 53'') and one of the first tracks (33, 34; 33'', 34''), The first tracks (33, 34; 33'', 34'') face each other radially, the second tracks (52, 53; 52'', 53'') face each other radially, and the first tracks (33, 34; 33'', 34'') and the second tracks (52, 53; 52'', 53'') face each other radially, The locking element (55; 55'') is parallel to the first axis (A) with respect to the third ring (31; 31''), - An insertion position reached in the standard configuration, where the locking element (55; 55'') is at a first axial distance from the third ring (31; 31''), - A withdrawal position reached in the first or second emergency configuration, where the locking element (55; 55'') is at a second axial distance greater than the first axial distance from the third ring (31; 31''), A torque balancing rotor (4; 4'; 4'') characterized by being slidable between them. Claim 2 The torque-balancing rotor according to claim 1, characterized in that the second orbit (52, 53; 52'', 53'') is radially inside the first orbit (33, 34; 33'', 34'') in relation to the first axis (A).

3. - Two axially spaced rings of the first rolling element (32; 32''), - Two axially spaced rings of the second rolling element (51; 51'') The torque-balancing rotor according to claim 1 or 2, characterized by comprising the same.

4. The torque-balancing rotor according to claim 3, characterized in that the second rolling element (51; 51'') and / or the first rolling element (32; 32'') are preloaded axially.

5. The torque-balancing rotor according to any one of claims 1 to 4, characterized in that the second rolling element (51; 51'') is a tapered roller.

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