WO2013026963A1

WO2013026963A1 - Helicopter rotor system, and helicopter including such a rotor system

Info

Publication number: WO2013026963A1
Application number: PCT/FR2011/051968
Authority: WO
Inventors: René Félix Charles KOKKELINK
Original assignee: Kokkelink Rene Felix Charles
Priority date: 2011-08-25
Filing date: 2011-08-25
Publication date: 2013-02-28

Abstract

The invention relates to a helicopter rotor system and to a helicopter including such a rotor system. Said rotor system has a rotor shaft (8) extending along a main axis, a rotor head (4) for supporting variable-pitch blades (6), the rotor head (4) being attached to the rotor shaft (8) and hinged relative to the rotor shaft (8) so as to be capable of tilting relative to the rotor shaft (8), and a pitch-controlling device (12) for varying the pitch of the blades (6). According to one aspect of the invention, the system includes a tilt-controlling device (14) for imparting a tilt to the rotor head (4).

Description

Helicopter rotor system and helicopter comprising such a rotor system

The present invention relates to a helicopter rotor system, of the type comprising a rotor shaft extending along a main axis, a rotor hub for supporting variable pitch blades forming with the rotor hub a rotor having a rotor axis. rotor, the rotor hub being coupled to the rotor shaft and articulated with respect to the rotor shaft so as to be inclined relative to the rotor shaft, and a pitch control device for varying the pitch of blades.

The pitch control device allows collective pitch control to change the pitch of each blade steadily over a revolution of the rotor to control the vertical movement of the helicopter.

The pitch control device provides cyclic pitch control varying the pitch of each blade so that it varies cyclically or sinusoidally over a revolution of the rotor to control the horizontal movement of the helicopter. The cyclic pitch control changes the lift of the blades so that a first zone of the rotor disk described by the rotating blades has a higher lift than a second zone of the rotor disk. The difference in lift tends to tilt the rotor which allows the horizontal movement of the helicopter.

Helicopters, and in particular radio-controlled helicopters, are difficult to maneuver. In order to improve the stability of a helicopter, it is possible to provide the rotor head with stabilizer bars or "Bell bars" which stabilize the rotor head by gyroscopic effect. It is also possible to equip the helicopter with gyroscopes to measure the inclination of the helicopter and an electronic flight control system. Nevertheless, these solutions are complex and expensive.

An object of the invention is to provide a helicopter rotor system for a stable flight and precise control, and which is simple to perform and inexpensive.

For this purpose, the invention proposes a helicopter rotor system comprising a rotor shaft extending along a main axis, a rotor head for supporting variable pitch blades, the rotor head being coupled to the shaft. rotor and articulated with respect to the rotor shaft so as to be inclined with respect to the rotor shaft, and a pitch control device for varying the pitch of the blades, characterized in that it comprises a tilt control device for imposing an inclination to the rotor head.

According to another embodiment, the rotor system comprises one or more of the following characteristics, taken separately or in any technically possible combination: - The inclination control device is coupled to the pitch control device so that the inclination imposed on the rotor head is a function of the cyclic pitch imposed on the blades;

- The inclination control device is provided for inclining the rotor head in the opposite direction of a moment induced by a lift imbalance resulting from the cyclic pitch of the blades;

the inclination control device and the pitch control device are adjustable so as to adjust the relation between the inclination at the rotor head and the cyclic pitch imposed on the blades;

the pitch control device comprises a swashplate, a modification of the inclination of the swashplate with respect to the main axis which modifies the cyclic pitch of the vanes and an axial displacement of the swashplate along the main axis modifying the not collective blades;

the pitch control device comprises a transmission mechanism for converting a shift of the swashplate into a pitch change of each blade;

the transmission mechanism comprises a transmission support disposed along the drive shaft and, for each blade, a transmission lever pivotally mounted on the transmission support, the axial position of the transmission support along the transmission shaft; rotor shaft being adjustable;

- The tilt control device comprises at least one tilt rod connecting a rotating ring of the swashplate to the rotor head;

- The rotor head comprises at least one arm for supporting a blade, the tilt rod is connected to the arm by a ball joint;

the rotor head is slidably mounted axially with respect to the rotor shaft; - The rotor head is articulated on a head support mounted to slide axially on the rotor shaft;

the pitch control device makes it possible to modify the collective pitch of the blades;

it comprises blades mounted on the rotor head.

The invention also relates to a helicopter comprising a rotor system as defined above.

The invention also relates to a helicopter rotor head for mounting variable pitch rotor blades, comprising a rotor hub comprising arms each for mounting a respective blade to rotate about a blade axis, and at least one ball joint slidably mounted on the rotor hub along a blade axis. The invention and its advantages will be better understood on reading the description which follows, given solely by way of nonlimiting example and with reference to the appended drawings, in which:

- Figures 1 to 3 are schematic side views of a helicopter rotor system according to the invention, in different configurations;

- Figure 4 is a schematic view illustrating helicopters with a rotor head according to the invention with different settings; and

- Figure 5 is a schematic detail view of a rotor system according to a variant of the invention.

The rotor system 2 illustrated in FIGS. 1-3 is a helicopter main rotor system intended to provide lift and propulsion for a helicopter.

The rotor system 2 comprises a rotor 3 comprising a rotor head 4 and a plurality of variable pitch blades 6 mounted on the rotor head 4 and extending from the rotor head 4. Only the blade roots 7 of the blades 6 are visible in Figures 1 to 3.

The rotor 3 has a rotor axis R-R around which the blades 6 are distributed.

The blades 6 extend from the rotor head 4 substantially radially relative to the rotor axis R-R. In rotation, the blades 6 describe a rotor disc of axis the rotor axis R-R.

In the example shown, the rotor 3 comprises two diametrically opposed blades 6. Alternatively, the rotor comprises more than two blades, for example three blades, four blades or more.

The rotor system 2 comprises a rotor shaft 8 extending along a principal axis AA for the rotational driving of the rotor 3, the rotor head 4 being coupled to the rotor shaft 8 by being of varying inclination relative to the rotor shaft 8. to the rotor shaft 8, a pitch control device 12 for varying pitch of the blades, and a tilt control device 14 for varying the inclination of the rotor head relative to the rotor shaft. rotor 8.

The rotor shaft 8 is provided to be rotated about the main axis A-A to drive the rotor 3 in rotation.

The rotor head 4 supports each blade 6. Each blade 6 extends radially substantially along a blade axis B-B. Each blade 6 is supported by the rotor head 4 to rotate about its blade axis B-B. The rotation of each blade 6 around its blade axis B-B changes the pitch of the blade. A pitch change of a blade changes its angle of incidence during the rotation of the blades 6, and therefore its lift.

The BB blade axes are concurrent and intersect the RR rotor axis. In the example shown, the blade axes BB are merged. The rotor head 4 is coupled to the rotor shaft 8 so as to be rotated by the rotor shaft 8 and articulated with respect to the rotor shaft 8 so as to be able to tilt relative to the rotor shaft 8. rotor shaft 8.

In the example shown, the rotor head 4 is rotatable relative to the rotor shaft 8 about an axis of articulation C-C perpendicular to the main axis A-A. The rotor system 2 comprises a head support 16 slidably mounted at an upper end of the rotor shaft 8 along the main axis AA, the rotor head 4 being rotatably mounted on the head support 16 about the axis. articulation CC via a hinge shaft 18 extending along the hinge axis CC.

The head support 16 is slidably mounted along the rotor shaft 8 along the main axis A-A. Thus, the rotor head 4 is itself sliding relative to the rotor shaft 8 along the main axis A-A.

The rotor head 4 comprises a rotor hub 10 having a central portion 19 and arms 20 extending radially from the central portion 19, here two arms 20, each arm 20 supporting a respective blade 6 rotated around its BB blade axis.

The rotor head 4 comprises blade fasteners 22 each for mounting a blade 6 on a respective arm of the rotor hub 10. Each blade attachment 22 is rotatably mounted on an arm 20 about the blade axis BB.

Each blade attachment 22 is provided for attachment of a blade root 7. Each blade attachment 22 comprises a clevis defined by two cheeks delimiting between them a receiving space of the blade root 7.

Each blade attachment 22 comprises a control finger 24 eccentric with respect to the blade axis B-B. A single control finger 24 (left) is visible in Figure 1 the other being hidden. The displacement of the control finger 24 makes it possible to modify the angular position of the blade attachment 22 around the blade axis B-B and therefore the pitch of the corresponding blade 6.

The pitch control device 12 comprises a swash plate 26 comprising a non-rotating ring 28 and a rotating ring 30 surrounding the main shaft 8. The non-rotating ring 28 and the rotating ring 30 are articulated on the rotor shaft 8 by via a ball 32 so as to be inclined with respect to the rotor shaft 8 and slide axially along the rotor shaft 8.

The non-rotating crown 28 and the rotating crown 30 bow and slide together and thereafter we will speak of inclination and sliding of the plateau cyclic 26 for designating the inclination and the sliding of the non-rotating crown 28 and the rotating ring 30

The rotating ring 30 is integral in rotation with the rotor shaft 8. The non-rotating ring 28 is locked in rotation about the main axis AA by a locking device 34 comprising a pin 36 integral with the non-rotating ring 28 is sliding in a guide 38 intended to be fixed on the structure of the helicopter.

The pitch control device 12 comprises control rods 40, here two control rods 40, each comprising one of its ends hinged to the non-rotating crown 28 by means of a control ball joint, and the other of its end intended to be connected to an actuator, for example a servomotor. The displacement of the control rods 40 makes it possible to control the inclination of the swashplate 26 with respect to the rotor shaft 8.

The pitch control device 12 comprises a transmission mechanism 44 connecting the rotating ring gear 30 to the blades 6 so as to convert the movements of the rotating ring gear 30 relative to the rotor shaft 8 into a rotation of each blade 6 around its BB blade axis.

The transmission mechanism 44 comprises for each blade 6 a transmission assembly 46 comprising a return lever 48 pivotally mounted relative to the rotor shaft 8 around a return axis EE and having one of its ends connected by a first transmission link 50 to the rotating ring 30 and the other of its end connected by a second transmission rod 52 to the control finger of the blade attachment.

The return levers 48 are arranged on either side of the rotor shaft 8 symmetrically. A return lever 48 is in front of the other and in front of the rotor shaft 8 in FIGS. 1 to 3, the other return lever 48 passing behind the rotor shaft 8.

The return axis E-E of each lever is perpendicular to the main axis A-A while being offset with respect thereto so that the main axis A-A does not cross the return axes E-E. The return axes are arranged on both sides of the main axis A-A symmetrically.

The first transmission link 50 of each transmission assembly 46 is connected to each of the rotating ring 30 and the deflection lever 48 by a ball joint, and the second transmission rod 52 is connected to each of the return lever 48 and the finger 22 by a ball joint. In the illustrated example, each transmission assembly connects a portion of the rotating ring 30 to a blade 6 substantially diametrically opposite to the main axis AA.

The transmission mechanism 44 comprises a transmission support 54 fixed on the rotor shaft 8 axially between the swashplate 26 and the rotor hub 10. Each deflection lever 48 is rotatably mounted about its return axis EE on the support of FIG. transmission 54.

The tilt control device 14 comprises at least one tilt rod 56, here two tilt rods 56. Each tilt rod 56 has one of its ends connected to the rotating ring 30 and the other to the rotor hub 10 so as to convert an inclination of the rotating ring 30 to a corresponding inclination of the rotor head 4. The ends of each inclination rod 56 are connected to the rotating ring 30 and the rotor hub 10 by ball joints.

The tilt rods 56 are arranged so that the rotor hub 10 inclines in the same direction as the swashplate 26. In the illustrated example, each tilt rod 56 connects an arm 20 of the rotor hub 10 to a portion of the rotating ring 30 located in the same radial direction with respect to the main axis AA.

The rotor system includes a return mechanism 58 for biasing the rotor head 4 into a rest configuration shown in FIG. The return mechanism 58 is configured to return the hub support 16 axially downwardly along the rotor shaft 8.

The return mechanism 58 comprises at least one return assembly 60, here two return assemblies 60, each comprising a return rod 62 fixed on the hub support 16 sliding through the transmission support 54 and a return spring 64 disposed along the return rod 62 so as to return the hub support towards the transmission support 54.

In operation, the rotor shaft 8 is rotated by a motor (not shown). The rotor shaft 8 drives the rotor head 4 in rotation about the rotor axis R-R. The blades 6 rotate by describing a rotor disc around the rotor axis R-R, which provides lift for the helicopter. The non-rotating crown 28 remains stationary in rotation around the main axis A-A and the rotating ring 30 rotates with the rotor head 4 in rotation about the main axis A-A.

The displacement of the control rods 40 makes it possible to control the axial sliding of the swashplate 26 along the rotor shaft 8 and its inclination with respect to the rotor shaft 8. In a rest position shown in Figure 1, the swash plate 26 is lowered along the rotor shaft 8 and aligned with the main axis AA. The pitch of the blades 6 is low and the blades 6 provide a lift that is not sufficient to maintain the helicopter in lift. The helicopter descends vertically or stays on the ground.

In a lift position illustrated in Figure 2, the swashplate 26 is mounted along the rotor shaft 8 while remaining aligned with the main axis A-A. The axial displacement of the rotary current 30 is converted by the transmission mechanism 44 into an identical traction of the control fingers 20 downwards relative to the rotor hub 10. As a result, the blades 6 are pivoted so that their pitch is increased relative to the rest position of Figure 1. The blades 6 generate sufficient lift to keep the helicopter in lift. The helicopter maintains its altitude or climbs vertically.

Such axial displacement of the swashplate 26 is controlled collective pitch of the blades 6: the pitch change of each blade 6 is identical on a rotor turn.

Note that due to the presence of tilt rods 56, an axial displacement of the non-rotating ring 28 causes an axial displacement of the rotor head. The rotor head 4 slidably mounted axially with respect to the rotor shaft 8 allows the rotor head 4 to accompany the axial movement of the swashplate 26.

In a horizontal displacement configuration shown in FIG. 3, the swashplate 26 is inclined with respect to the rotor shaft 8 by an angle α (to the right in FIG. 3).

Due to the inclination, the positions of the transmission assemblies 46 are different and the control fingers 22 are moved differently. The pitch of the blade 6 on the left in FIG. 3 is different from the pitch of the blade 6 on the right in FIG. 3.

The pitch of each blade 6 varies according to its angular position around the main axis A-A. On a rotor revolution, the pitch of a blade 6 varies cyclically or sinusoidally. The inclination of the swashplate 26 controls the cyclic pitch of the blades 6.

Because of the cyclic pitch of the blades 6, the rotor 3 generates an unbalanced lift, the lift being greater in the high pitch zone of the blades 6 and lower in the reduced lift zone of the blades 6. This difference in lift induces a moment on the rotor 3 which tends to tilt in such a way that the high lift zone is raised and the reduced lift zone is lowered.

In the example illustrated, the pitch of the blade 6 on the left in FIG. 3 is smaller than the pitch of the blade on the right in FIG. 3, and the rotor 3 is tilted to the left because of the imbalance of lift. Due to the presence of the transmission mechanism 44 which includes return levers 48, the rotor 3 tends to tilt due to cyclic pitch in the opposite direction of the swashplate 26.

The inclination control device 14 acts on the rotor head and imposes on the rotor head 4, and thus on the rotor 3, an inclination with respect to the main axis A-A. The inclination control device 14 counteracts the moment induced by the cyclic pitch of the blades 6.

In the illustrated example, the tilt rods 56 are arranged so that the inclination control device 14 inclines the rotor 3 in the opposite direction of the moment induced by the cyclic pitch.

The tilt control device 14 is coupled to the pitch control device 12. The tilt rods 56 are connected to the rotating ring 30 such that the inclination of the rotor 3 is a function of the collective pitch imposed on the blades 6 .

The relationship between the inclination of the rotor 3 and the cyclic pitch of the blades 6 can be adjusted.

As illustrated in Figure 4, it is possible to adjust the tilt rods 56 so as to modify the relationship between the inclination of the swash plate 26, which controls the cyclic pitch of the blades 6, and the inclination of the 4. To do this, it is possible to vary relative to each other the spacing between the connecting ball joints of the tilt rods 56 to the rotor hub 10 and the distances between the ball joints. connecting the tilt rods 56 to the swashplate 26. It is possible to provide an equal spacing (left in FIG. 4), greater than the level of the rotor hub 10 (in the center in FIG. 4) or less than the level of the rotor hub 10 (in the center in FIG. rotor hub 10 (right in Figure 4).

In a particular embodiment illustrated in FIG. 5, the rotor system

2 comprises an adjusting device for adjusting the spacing of the connecting ball joints of the tilt rods.

As illustrated in Figure 5, the ball 70 connecting each tilt rod 56 to the rotor hub 10 is slidably mounted along the arm 20 corresponding to the blade axis B-B. The adjusting device comprises an adjusting member 72 for controlling the axial position of the ball joint along the arm. The adjusting member 72 comprises a fixed portion 74 integral with the arm 20 and a movable portion 76 integral with the ball joint.

In a first variant, the adjustment member 72 is manually actuated, the fixed portion 74 and the movable portion 76 comprising, for example, complementary threads enabling the screw to adjust the relative axial position of the fixed part 74 and the moving part. 76 and block them together. In a second variant, the adjustment member 72 defines an actuator that can generate a displacement force of the movable portion 76 relative to the fixed portion 74. The adjustment member 72 is for example of the fluidic cylinder type, including hydraulic. In some cases, the fixed portion 74 and the movable portion 76 define between them a sealed chamber and the regulator 72 comprises a conduit 78 for supplying the chamber with fluid under pressure.

Advantageously, as illustrated in Figure 5, the fixed portion 74 is integral with the rotor hub 10, more particularly with the central portion 19 thereof.

Alternatively or optionally, the axial position of the transmission medium 54 along the rotor shaft 8 is adjustable. A modification of the axial position of the transmission support 54 along the rotor shaft 8 modifies the relationship between the pitch of the blades and the inclination of the swashplate 26.

Thanks to the invention, it is possible for situations of horizontal displacement (left / right or front / rear) to impose on the rotor disk an inclination with respect to the vertical lower than that which the rotor disk would adopt in the absence of a device. tilt control. This makes it possible to obtain stable behavior and precise control of the helicopter.

The inclination of the rotor disk in the opposite direction of the inclination moment induced by the cyclic pitch of the blades makes it possible to obtain a particularly lively and pleasant behavior of the helicopter, without delay during the commands of horizontal displacement of the helicopter, while keeping a helicopter with good stability that is easy to fly.

Tilt control is simple and inexpensive.

The invention applies to helicopters of all sizes and in particular to modeled radio-controlled helicopters.

Claims

1. - Helicopter rotor system comprising a rotor shaft (8) extending along a main axis, a rotor head (4) for supporting blades (6) with variable pitch, the rotor head (4) being coupled to the rotor shaft (8) and articulated with respect to the rotor shaft (8) so as to be inclined with respect to the rotor shaft (8), and a pitch control device (12) ) to vary the pitch of blades (6), characterized in that it comprises a tilt control device (14) for imposing an inclination to the rotor head (4).

The rotor system according to claim 1, wherein the inclination control device (14) is coupled to the pitch control device (12) so that the inclination imposed on the rotor head (4) is cyclic pitch function imposed on the blades (6).

The rotor system according to claim 1 or 2, wherein the inclination control device (14) is provided for inclining the rotor head (4) in opposite directions by a moment induced by a resulting lift imbalance. cyclic pitch of the blades (6).

The rotor system according to claim 2 or 3, wherein the inclination control device (14) and the pitch control device (12) are adjustable to adjust the relationship between the inclination to the head. rotor (4) and the cyclic pitch imposed on the blades (6).

The rotor system according to any one of the preceding claims, wherein the pitch control device (12) comprises a swashplate (26), a change in the inclination of the swashplate (26) relative to the main axis (AA) modifying the cyclic pitch of the blades (6) and an axial displacement of the swashplate (26) along the main axis (AA) modifying the collective pitch of the blades (6).

The rotor system of claim 5, wherein the pitch control device (12) comprises a transmission mechanism for converting a shift of the swashplate (26) into a pitch change of each blade (6).

The rotor system according to claim 6, wherein the transmission mechanism comprises a transmission support (54) disposed along the drive shaft and for each blade a pivotally mounted transmission lever (48). on the transmission support (54), the axial position of the transmission support (54) along the rotor shaft (8) being adjustable.

The rotor system according to any one of claims 5 to 7, wherein the tilt control device (14) comprises at least one tilt rod.

(56) connecting a rotating ring (30) of the swashplate (26) to the rotor head (4).

9. - A rotor system according to claim 8, wherein the rotor head (4) comprises at least one arm (20) for supporting a blade (6), the tilt rod (56) is connected to the arm (20). ) by a ball joint.

10. - rotor system according to any one of the preceding claims, wherein the rotor head (4) is slidably mounted axially relative to the rotor shaft (8).

1 1. - Rotor system according to claim 10, wherein the rotor head (4) is articulated on a head support (16) axially slidably mounted on the rotor shaft (8).

12. - rotor system according to any one of the preceding claims, wherein the pitch control device (12) allows to change the collective pitch of the blades.

13. - Helicopter rotor system comprising blades (6) mounted on the rotor head (4).

14. Helicopter comprising a rotor system according to any one of claims 1 to 13.

15. - Helicopter rotor head for mounting variable pitch rotor blades, comprising a rotor hub (10) comprising arms (20) each for mounting a respective blade to rotate about an axis blade (BB), and at least one ball joint slidably mounted on the rotor hub (10) along a blade axis (BB).