FR2658565A1 - Simplified rotor blade with autonomous regulation by automatically varying the pitch - Google Patents

Abstract

The invention relates to a rotor blade with autonomous regulation by automatic pitch variation, obtained by placing the blades in static and dynamic imbalance. According to the invention, the rotor blade is equipped with blades (1) mounted in the cantilever manner which exhibit, by rotation, a concave face pointing towards the arrival of the driving flux (arrows 13 and 14) as regards productive blades; each blade is thus urged from front to back by centrifugal force, the pressure of the fluid and the torque, thereby assuming the pitch (view B), if necessary, until it is feathered. Each blade is fastened to a hub by an asymmetric articulation system, the main articulation point (6) is located at the front and close to the blade root (9), the second one (7) is placed at the end of an arm (10) and, with respect to the axis of rotation X-X', opposite the main point (6). Moreover, a synchronising device (15) ensures coherency of movement of the blades with respect to each other, a spring (19) holds the blades in their initial situation until the nominal speed has been reached. A damping device makes it possible, on the other hand, to avoid jolts when changing pitch. The invention applies, particularly, to low-power hydraulic or wind-propelled energy-producing blades, as well as to propulsive blades for various uses.

Description

 The invention relates to a simplified rotor-propeller with autonomous regulation by automatic variation of pitch obtained by static and dynamic imbalance of the blades, in particular intended for hydraulic and wind motors of small dimensions.

 In order to avoid the complexity of the variable pitch, a certain number of manufacturers confine themselves to the fixed pitch and limit the pressures on the propellers by reducing, in particular, the surface of the blades and their warping, leaving aside the notion of efficiency.

 It has however been obvious, for a very long time, that propellers are productive or propulsive (in the case of boat and airplane propellers) that it is essential to warp the blades correctly and to vary the pitch, so as to obtain satisfactory results.

 The variable pitch, in addition to this aspect of performance, allows, enormous advantage, to define precisely and limit the forces exerted on the propellers by eliminating all the risks of destruction by progressive eclipsing of the blades.

 Regulated hydraulic propellers, Kaplan type, for example, have the drawback of using a complex system of orientation of rotor blades with external servo-control, a regulator allowing to act at best on the angle of incidence of the blades according to the available flow and the speed of rotation to be obtained.

 Wind propellers equipped with autonomous and automatic regulation devices exist, but their very studied structures are, technically, difficult to transpose and too cost price for low power wind turbines.

 The invention which is the subject of this patent makes it possible, in particular, to produce hydraulic and wind propellers with autonomous regulation by variable pitch, at a cost price in relation to the permitted power.

 In the case of this rotor-propeller, the regulation is obtained by static and dynamic imbalance of the blades and includes, for this purpose, joints placed in asymmetry, a hub intended to receive a certain number of blades and means of synchronization of pitch different blades between them, assisted by damping and compensating means.

 The rotor-propeller, according to the invention, makes it imperative to describe the blades constituting it, by rotation, a cone of concave revolution, of approximately 155 degrees of opening, turned towards the origin of the current with regard to the producing machines. energy and thus achieve better capture while avoiding centrifugal effects; two essential parameters for reaching an optimum yield.

 The mechanism is simple and safe; the blades are cantilever mounted but articulated from front to back, maintained at a predetermined incidence below the nominal speed of rotation by a spring system and, beyond, slide backwards, in the direction of the current, taking a step until feathering under the action of pressure exerted by the current, centrifugal force and torque.

 An essential embodiment, according to the invention, consists in hooking each blade to two articulations placed asymmetrically on a hub, the axis of these articulations being neither on the same axis, nor parallel to the axis of the blade, but is carried forward, in the direction of rotation, on the leading edge of the blade, forming an open angle on the outside.

 According to a preferred embodiment, the asymmetrical joints are of the ball-joint type so as to allow a movement in all the planes, or as a variant, are in the extension of one another in order to produce an aligned bearing system.

 According to another preferred embodiment, the main articulation is placed at the foot of the blade, at a certain distance, but close to the leading edge, in order to produce a mass and a rear surface sufficiently offset to cause feathering by difference in pressure and mass subjected to centrifugal force.

 According to a preferred embodiment, the second articulation is arranged opposite the main articulation, relative to the axis of the hub, at the end of an arm fixed to the rear of the blade root; this articulation being offset behind the main articulation with respect to the direction of the working fluid.

 According to an advantageous embodiment, the rotor is equipped with a number of blades, synchronized with one another, in their movements, by a central slide moving in the axis of rotation of the rotor.

 According to an advantageous embodiment, the connection between the blade and the synchronizing slide is ensured by connecting rods bearing on one end in housings of the slide and, on the other, at the base of the arm of the secondary articulation of the blades. .

 According to yet another embodiment, a compression spring ensures the maintenance of the bucket grout at its initial position until the rotor has reached its nominal speed, then flexes beyond it, letting the blades go to the rear. by disappearing.

 According to a preferred additional embodiment, the slide moves longitudinally in the axis of the hub on a damping cylinder device which prevents bounces and jerks of pitch change, using calibrated orifices and, if necessary compensating valves.

 According to a previous complementary embodiment, an anti-torque device keeps the slide in rotation relative to the hub, in order to counteract the reaction of the connecting rods.

 According to a last preferred embodiment, each blade abuts, at nominal incidence, on a screw and lock nut device capable of performing the best basic setting and a punctual return after regulation.

 This self-regulating rotor-propeller is not only applicable to energy-producing propellers, but also relates to propeller propellers, in particular for light aircraft; the dihedral of the blades then forming a cone directed towards the rear of the apparatus, the variation in pitch being achieved in compromise with peripheral speed and wing pressure.

 The rotor-propeller according to the invention will be better understood after the description which follows and the drawings placed in the appendices which show the example presented for illustrative purposes.

 - Figure 1 shows the transverse geometry of the rotor-propeller according to the invention, in the rest position.

 - Figure 2 is a front view of said rotor, a single blade being shown.

 - Figures 3 and 4 are perspectives of one of the blades, in the initial position, then in the eclipsing position.

 - Figures 5 and 6 show the detail, in section, of the synchronization device and a variant of adjusting the return spring.

 - Figures 7 and 8 show schematically the adjustment stop and the anti-torque system of the synchronizer.

 As shown in Figure 1, the rotor-propeller, according to the invention, is formed of blades 1 and 2, limited to this number in the description to facilitate the understanding of the drawing of the example presented, attached to a hub 3 focused on X-X '.

 The blades 1 and 2, in the rest position, form between them a cone of revolution close to 1550, concave in the direction of the origin of the current, in the case of propellers producing energy.

It should be remembered that this geometry is essential because it avoids the effects of centrifugal flows (work of
BETZ) and thus maintain a practically laminar flow, imperative to obtain an optimal category, in particular when the available power, at the moment considered, is reduced.

 The power gain is around 28% compared to a warped flat propeller, and reaches more than 50% for a flat propeller with dynamic stall regulation.

 This capture geometry of lesser interest on a static scale (works by EIFFEL), however, facilitates start-up.

 In the case of this rotor-propeller, and according to the first embodiment of the invention, this conical arrangement is, moreover, essential in the state of rest and below the nominal speed, so that the blades can be biased backwards in the direction of arrows 4 and 5 at an angle e with respect to the plane YY 'beyond the speed limit allowed.

 The cone a must remain practically punctual until the nominal power, corresponding to a defined speed of rotation, is reached.

 In Figure 2 which is a 900 view of the previous one, we see that each blade 1 or 2 is attached to its hub 3 by two points 6 and 7, placed in complete asymmetry with respect to the virtual axis OO 'of the pale, assumed to be the dynamic equilibrium axis.

 Thus each blade 1 and 2 is articulated on these two points 6 and 7 by forming a line of articulation ZZ 'offset from the virtual axis OO' of the blade, the extension of the axis ZZ 'towards the outside. of the rotor located in front of the virtual axis OO 'by forming an angle ss, the direction of rotation of the rotor being defined by arrow 8.

 The articulation point 6 constitutes the main attachment of the blade on which it is located at the foot and near the front edge 9.

 The second articulation point 7 is placed at the end of an arm 10 fixed to the rear part of the blade root, this point 7 is, like point 6, integral with the hub 3, but located in the 'example presented and according to a preferred mode, substantially opposite point 6 with respect to the axis of rotation XX' and, furthermore, behind point 6 with respect to the plane YY 'with reference to FIG. 1 , the upstream situation being determined by the concave shape of the cone described by the blades, in the case of captive propellers.

 It is clearly seen, in FIG. 2, that the surface 11 and the mass of the blade are completely off-center with respect to the axis ZZ 'of the joints 6 and 7, and that, consequently, the blades are necessarily biased from before rear, causing the blades to rotate on themselves, and thus an increase in pitch, the blades then having a tendency to return to plane along YY ', under the action of the pressure exerted on the surface of the blades and the centrifugal force undergone by the mass of said blades.

 In FIG. 3, the blade is shown in the rest position or at a rotational speed lower than the nominal value, and seen with a certain warping necessary for obtaining a good yield.

 The mechanism of action according to the invention will be more easily understood and the necessity of having each blade describe an angle e with respect to the plane of rotation Y-Y '.

 We can easily distinguish the points of articulation and attachment 6 and 7 of the blades to the hub 3; these points 6 and 7 being placed, as seen previously, in asymmetry with respect to the virtual axis OO 'of the blade and the axis of rotation X-X', the axis ZZ 'of the articulations forming with the axis virtual OO 'of the blades an angle ss open in front of the direction of rotation defined by arrow 8.

 Point 6, as also seen previously, is placed at the foot of the blade, near the front or leading edge 9; point 7 in the rear position of the blade at the end of an arm 10 and, according to a preferred embodiment, substantially opposite point 6 with respect to the axis of rotation XX '.

 The blades are kept punctually in the rest position or in rotation, until the nominal speed is reached, by means of restraint which will be described later.

Figure 4 shows the eclipsing of the blade 1 which, pivoting on the axis
Z-Z ', in the direction of arrow 12, slips back and forth in the direction of the motor current (in the case of energy-producing propellers) materialized by arrows 13 and 14.

 This eclipse results, as has been said previously, from the pressure of the current and from the centrifugal force which, acting on the offset axis 11 of the blade, tends to achieve and exceed the flatness, the cone then evolving towards a convex situation by making a negative angle e.

 Referring again to FIG. 3, it can be seen that, according to one embodiment of the invention, the blades are synchronized with one another, during their eclipsing movement, by a device 15 sliding on the hub 3 along the 'axis XX' and acting on the blades via connecting rods 16, each of these connecting rods bearing, at one end, in a housing 17 of the device 15 and, on the other, in a housing 18 located on the arm 10, near the blade root.

 In order to maintain and return the rotor-propeller to its original position, a helical spring 19 is placed behind the synchronization device 15 and, like the latter, centered on the axis of rotation XX '.

 The calibration of this spring 19 is defined beforehand, its deflection ensuring the disengagement of the blades towards the rear when the nominal rotation speed is reached.

 In FIG. 4, the eclipsing is carried out and the spring is compressed, ready to return the blades, partially or entirely, to the original position, if the current or the speed of rotation decrease.

 Returning to FIG. 3, there is a setting stop 20, secured to the hub 3, intended to come into contact, at rest, with the arm 10 of the blade in order to limit the action of the spring by guaranteeing a punctual return to the primitive setting, while in Figure 4 the blade arm has left the contact of the stopper to reach an eclipsing position.

 FIG. 5 allows us to better understand the embodiment according to the invention of the synchronization device 15 which is constituted in particular, in the example presented, by a plate 21 welded or fixed to a slide tube 22, partially obstructed at a of its ends 23, provided with a sliding ring 24 allowing satisfactory longitudinal sliding on a rod 25 screwed onto the hub 3 in the axis XX '.

 The plate 21 has, at its periphery, the housings 17, in a number equal to that of the blades of the rotor-propeller.

 These housings 17 have a spherical bottom 26 and are provided with flaring 27 in order to receive and allow the movement of the connecting rods 16.

 The connecting rods 16 are terminated by spherical ends 28, one coming to bear in the housing 17, the other in the housing 18 of the arm 10, these housing 18 having characteristics identical to the previous ones.

 As mentioned, the slide tube 22 is only partially obstructed in order to allow the extension or reduction of the volume of air or water trapped.

 Its function is similar to that of a retarder cylinder whose calibrated orifice ensures flow control and, by this means, control of the speed of eclipsing movement of the blades.

 This calibrated orifice 29 is constituted, as a variant, by a nozzle 30 screwed onto the tube 22 and which, depending on whether the medium is aerial or hydraulic, has a defined passage diameter adapted to the viscosity of the fluid.

 To this nozzle can be added, also as a variant, a valve 31 capable of modulating or modifying the speed of movement of the fluid, in a predetermined direction, with the aim of facilitating or inhibiting the going or returning of the change of blade pitch.

 The spring 19, in order to exert a regular pressure, has a centering washer 32 resting directly on the rear of the synchronization device 15.

 It can be seen in FIG. 6 that the pressure exerted on the spring 19 is, as a variant, made adjustable by a flange nut 33 screwed onto a threaded support 34, integral with the hub 3, supporting the rear part 35 of the spring 19, in order to possibly be able to modify the initial calibration.

 Furthermore, so as to punctuate the position of the nut 33 after having made the adjustment, a screw 36 has been provided, coming to engage at the end of the race in the grooves 37 of the threaded support.

 In Figure 7, we see the mounting detail of the adjusting screws 20 consisting of a stop head 38 mounted at the end of a threaded rod 39, which is screwed in a homologous part of the hub 3, a lock nut 40 allowing to block this assembly.

 FIG. 8 completes the description by showing the anti-torque rods 41, which are of rectangular section and hooked by fasteners 42, from one end to the synchronizer 15 and, on the other, to the hub 3, using 'axes 43 and 44.

 This device, very conventional in principle, controls the position of the synchronizer 15 biased in rotation by the reaction of the connecting rods 16 and the compression spring 19, during regulation movements.

In operation, the regulation therefore operates under the action of the centrifugal force defined by the equation F = m V2 and the pressure of equa
R tion F = 1/2 m V2, these two parameters acting in complementarity and compromise.

 The rotor-propeller under the action of centrifugal force and the pressure of the motor flow (in the case of energy-producing propellers) loses its conical shape of capture by slipping backwards, gaining momentum, possibly until flag and disappearance of the concavity.

 The flat, even convex shape, then obtained, joined to the increase in the pitch, reduce the surface offered to the current, and allows, on the other hand, in rotation the automatic release of grasses, algae and branches, which could catch on with the blades and hinder the smooth running.

 In the event of a rotation stop, the pressure is the only one acting and similar effects are obtained.

 The invention applies, in particular, to propellers producing low power power, hydraulic or wind, as well as propellers propellers of various uses.

Claims (9)

 1. Rotor-propeller with autonomous regulation by automatic variation of pitch obtained by placing the blades, of the cantilever type, in static and dynamic imbalance, with the possibility of total eclipsing of the blades, in particular intended for hydraulic and wind power engines, comprising, blades, describing by rotation, as regards the receiving machines, a concavity of capture directed towards the arrival of the flow, means for hooking the blades to the hub allowing their deflection towards the rear and synchronization means assisted by control means, characterized in that the means for hooking the blades (1 and 2) to the hub (3), forming an angle a between them, are formed for each blade by two articulations (6 and 7) placed asymmetrically, the axis (Z-Z ') of these articulations being neither in the same axis, nor parallel to the virtual axis (O-O') of the blade, the main articulation (6) being placed at the front and at the foot of blade, the second (7) opposite the first with respect to the axis XX 'of the hub and, at the end of an arm (10), the movement of the blades towards the rear causing an increase in not, the synchronization of the movement of the blades, between them, being carried out by a device (15) sliding on the axis XX 'of the hub connected to the arm (10) by connecting rods (16), a spring (19) returning the device sliding and the blades in their original position, rods (38) counteracting the reaction of the spring, while a damping-compensating system also prevents jolts of movement, a stop ensuring, moreover, a punctual return after regulation movement.  2. Rotor-propeller, according to claim 1, characterized in that the blades (1 and 2 or more), of the cantilever type, are hooked independently to the hub (3), imperatively forming between them, at rest, an angle directed towards the arrival of the flow, using two articulations (6) and (7) placed in asymmetry with respect to the virtual axis OO 'of the blade, this axis bearing in front of the leading edge (9) of the blade in the direction of rotation (8) by forming an angle ss open towards the periphery, in order to produce a mass and a rear surface sufficiently offset to cause, by difference in pressure and mass subject to centrifugal force, the increase in pitch until feathering of the blades.  3. Rotor-propeller, according to claims 1 and 2, characterized in that the main articulation (6) is placed at the front, near the leading edge and a blade root (9), the second point articulation (7) located opposite the main articulation with respect to the axis XX 'of rotation of the hub (3), and placed at the end of an arm (10) fixed to the part rear and foot of blade; these joints being of the ball-joint type so as to allow a displacement in all the planes, or, as a variant, are located in the extension of one another, oriented in Z-Z 'in order to produce an aligned bearing system.  4. Rotor-propeller, according to claims 1, 2 and 3, characterized in that it comprises a number of blades, equal to or greater than the number used by the description of the example, which, placed on independent articulations , have synchronization means between them in their pitch variation movements, consisting of a device (15) sliding on the axis XX 'of the hub (3) using a sliding ring (24) mounted inside the central tube (22) of the synchronization device, this ring moving on a rod (25) fixed, on the axis XX ', on the hub (3).  5. Rotor-propeller, according to claims 1 and 4, characterized in that the movement connection of the synchronization device (15) to the blades is ensured by connecting rods (16) with spherical ends bearing, on the one hand, in housings (17) of the synchronization device (15) and, on the other hand, at the base of the arm (10) of secondary articulation in the housings (18) of identical shape to the previous housings.  6. Rotor-propeller, according to claims 1, 4 and 5, characterized in that a compression spring (19) is placed behind the synchronization device (15) in order to oppose the eclipsing of the blades in maintaining the slide in its initial position, below the nominal speed of rotation, this spring (19) being centered relative to the axis of rotation XX 'of one end using a washer (32) and , alternatively, at the other end by a adjusting nut (32); beyond the nominal speed, this spring flexes, letting the blades go to the rear, slipping away.  7. Rotor-propeller, according to claims 1 and 4, characterized in that the slide tube (22) is partially obstructed and, using the sliding ring (24) and the support rod (25), constitutes , a jack system which allows the damping of the pitch change jerks, the partial closing being carried out by a calibrated orifice obtained in a variant, by the addition of a nozzle (30), the action of the latter being able to be reinforced, also alternatively by a valve device (31) promoting the passage of the ambient fluid in one direction to the detriment of the other.  8. Rotor-propeller, according to claims 1, 4 and 5, characterized in that the synchronization device (15) is provided with an anti-gyration assembly consisting of rods (41), each interposed between a fastener (42 ) placed at the periphery of the slide and another fastener secured to the hub (3); this assembly controlling the spontaneous rotational movement imparted by the reaction of the connecting rods and the spring.  9. Rotor-propeller, according to claim 1, characterized in that the action of the spring (19) is limited below the nominal rotation speed, by an adjustable stop (20) fixed to the hub (3), clean to perform and keep the best pitch setting base and a punctual return after regulation.