EP0207867B1 - Propeller or the like with joined blades - Google Patents

Abstract

A propeller according to the invention has a hub centered on and rotatable about a hub axis and formed with a bore extending along the axis and with a plurality of identical, radially outwardly open, and angularly equispaced sockets centered on socket axes extending at least generally radially of the hub axis. Respective identical blades each have a base complementary to and snugly fittable in the respective socket and an outer part extending radially outward from the hub along the respective socket axis when the respective base is fitted therein. Respective locks are provided in the hub for releasably fixing the bases in the respective sockets against relative movement between the respective blades and the hub. The sockets and bases are normally complementarily cylindrical and both centered when the bases are in the sockets on the respective socket axes. Thus the blades can turn about the respective socket axes on the hub when released by the respective locking means. In addition each socket is formed with an annular groove open inwardly radially of the respective socket axis and each base is formed with a similar annular but outwardly open groove confronting the respective inwardly open groove when the base is fitted in the respective socket and forming with the respective inwardly open groove an annular chamber. The system for locking includes a respective plurality of balls generally filling the chamber and something that can press the balls tightly against the respective grooves.

Description

The present invention relates in particular to fixed propellers comprising blades attached to a central hub, applicable to the propulsion of boats, and it also includes, more generally, all rotary devices with blading, having a similar structure with a central hub and blades, such as turbine wheels.

The fixed propellers of boats are currently made by a single piece of foundry, in a material such as cast iron, cupro-aluminum or stainless steel, this foundry piece bringing together in a single block the propeller hub and the different blades distributed around the hub.

The foundry mold used is made either using a wooden model reproducing the propeller hub and a blade, or using a metal model reproducing the complete propeller.

The first solution is the most frequently used. It is the least expensive for the construction of the model, but for its implementation it becomes the most expensive, longest and least precise solution. Indeed, the founder must successively make as many impressions as there are blades, or three or four in most cases, by angularly shifting the model several times around the axis of the hub.

In the two cases indicated here, there is also the disadvantage of having "rigid" models, definitively fixing the pitch of the propeller and the shape of each blade. Thus, we are led to enormously multiply the number of models used. In the case of the first solution, there is a possibility of modification of the pitch by inclination of the axis of the propeller hub relative to the origin, but this possibility remains limited; moreover, the new value of the pitch is actually obtained only on a single radius, usually equal to 0.7 times the radius of the helix.

The problem is of the same order for the hub: there is no possibility of modification, neither of the diameter, nor of the positions of attachment of the blades thereon. Here again, we are therefore led to multiply the foundry models.

The raw foundry propeller is then carefully deburred, but it cannot be used at this stage. Except for the machining of the hub, the blades must be ground over their entire surface, this on both sides. This operation is done manually by qualified personnel, in very difficult working conditions. Depending on the class of the propeller (defined by AFNOR and ISO standards), a pitch adjustment operation is made by more or less tight notching, before grinding. The propeller is finally balanced statically, and dynamically if necessary.

In the use of current propellers, produced as indicated above, the one-piece design also has drawbacks in the event of deterioration such as ruptures or deformations of blades due to impacts on rocks, piles of bridges, in locks, on floating tree trunks, etc ..., this kind of damage being frequent in river navigation. In such eventualities, the propeller must be repaired or completely rebuilt; repairs are costly and immobilize the boat.

We also know, for example from document BE-A-390294, propellers which are not fixed but which are said to be "with variable pitch", in which each blade is mounted to rotate about an axis perpendicular to the general axis of the hub, and can be oriented during the use of the propeller. More particularly, the document BE-A-390294 describes a propeller with a central hub at the periphery of which are housings of generally cylindrical shape, and with blades initially separated from the hub each having a base provided with a part of generally shaped cylindrical complementary to one of the hub housings. A first annular groove is hollowed out in the cylindrical side wall of each housing of the hub, and a second annular groove is hollowed out around the complementary part formed under the base of each blade. This last part is introduced into one of the housings, and the two grooves are then placed in coincidence so as to together form a toric cavity into which are introduced balls or other similar rolling members such as rollers.

These balls provide an axial connection of each blade with the hub, allowing the blades to rotate simultaneously under the action of a common control device. It is therefore here typically a propeller with adjustable pitch during use, which cannot be assimilated to a fixed propeller and which has, in particular, no means for the individual locking of each blade on the hub in an initially chosen position.

The present invention aims to eliminate all of the above drawbacks, by providing a new structure for propellers or the like of the "fixed propeller" type, providing a simplification of opera manufacturing and a significant lowering of cost prices, allowing a real adjustment of the pitch at the manufacturing and also later, and also reducing significantly the costs and repair times.

To this end, the subject of the invention is a propeller or the like with attached blades, with a central propeller hub at the periphery of which are housings of generally cylindrical shape and with blades initially separated from the hub, each blade having a base provided with a generally cylindrical part complementary to one of the housings of the hub, and capable of being inserted into one of these housings, means being provided for making a connection between each blade and the hub, these means comprising a first annular groove of semi-circular section hollowed out in the side wall of each housing of the hub, a second annular groove of semi-circular section hollowed out around the complementary part of this housing formed under the base of the corresponding blade, the two grooves being placed in coincidence during the introduction of said part into the housing, so as to form a toric cavity, and balls introduced into the toroidal cavity, this propeller or the like being characterized in that, to immobilize the blades in the desired positions, the aforementioned connecting means also include blocking means acting on the balls so as to push them against each other and pressing them against the walls of the toroidal cavity formed by the two grooves placed in coincidence. The balls thus ensure a total blocking of the blades on the hub by jamming, canceling all the games and also eliminating all the vibration problems. However, these balls allow, before blocking, to adjust the pitch of the propeller or to modify it, by rotating each blade around the axis of the corresponding cylindrical housing of the hub.

The hub advantageously comprises, for each cylindrical housing, at least one hole starting from the external surface of the hub and opening into the annular groove of the housing, the or each hole allowing the introduction of the balls into the toric cavity and then receiving the means for blocking acting on these balls. More particularly, it may be a tapped hole receiving an additional ball as well as a locking screw which, when tightened, acts on the balls housed in the toric cavity by means of the additional ball. The additional ball, which is supported between two balls of the cavity toric, then behaves like a wedge which pushes the other balls against each other, forcing them to be placed in staggered rows and thus blocking them against the walls of the toric cavity. In a variant, the or each aforementioned hole of the hub is a tapped hole receiving a locking screw with conical tip which, when tightened, acts directly on the balls housed in the toric cavity.

By simply loosening the locking screw, the blade can be released again, to readjust its position and possibly remove it for repair or replacement. For this purpose, a second hole can be drilled between the outer surface of the hub and the annular groove of each cylindrical housing, to facilitate the evacuation of the balls from the toric cavity by the action of a fluid or by mechanical action, means being provided to normally close this hole.

It is also possible to have two diametrically opposite holes, each receiving blocking means acting on the balls so as to press them against the walls of the toric cavity.

Security means of two types can be provided:

On the one hand, at least one pawn is advantageously provided for link in rotation in the desired relative position, the base of each blade and the hub, the or each pin being pressed into corresponding holes drilled in the base of the blade and at the periphery of the hub. The pins thus arranged reinforce the rotation blocking of the blades by wedging the balls, and they make it possible to identify the position of the blades relative to the hub, which makes it possible to detect any modification of the pitch of the propeller by the user.

On the other hand, an internally threaded plug, serving as a screw brake, is preferably screwed onto the or each ball locking screw and tightened against the outer surface of the hub, this plug behaving like a lock nut which prevents any accidental loosening of the locking screw.

Sealing means, in particular produced in the form of annular seals, are finally provided to prevent the entry of water into the fastening device of each blade, this in particular between the base of the blade and the outlet to the outside the corresponding housing of the hub, as well as at the level of the plugs blocking the inputs of the various holes of the hub.

The advantages of the invention result essentially from the fact that it offers a propeller with attached blades, therefore manufactured separately and not produced in one piece with the hub:

Thus, it becomes possible to envisage an easy standardization of the blades on the one hand, and of the hubs on the other hand. As a result, automatic molding on model plates is made profitable, and the high number of wooden models is eliminated, depending on the foundry process chosen. Standardization makes it possible to reduce the number of models of propellers, therefore makes it possible to store blades and hubs, hence the production of small series in foundries. These first advantages already bring a significant reduction in the costs of the raw propellers, while allowing very numerous combinations between blades and hubs.

These advantages also apply to the machining of the parts ensuring the connection between the hub and the blades, as well as between the hub and the propeller shaft. This is a feasible machining on inexpensive machine tools, since there are only turning and drilling operations. By equipping these machines with special positioning and clamping tools, by working with automatic information at the end of the tool stroke, the machining time is considerably reduced, and this the latter can be done in masked time by an operator who is not necessarily very qualified and who works on two machines.

With regard to the blades, molded separately, it is possible to obtain rough foundry blades with an optimal surface, the profile of the blades being adjusted by oxidation cutting on demand. This is also of great interest: the raw blades for propellers rotating in open water and for propellers mounted under a nozzle will be identical, which leads to an additional elimination of the necessary number of wooden foundry models.

In the foundry process using model plates, it will be possible to produce raw foundry parts with great precision, therefore approaching very closely the desired finished dimensions, which has the consequence of considerably reducing the grinding time; moreover, this operation will be much more like grooming, which can be carried out by operators without any particular qualification. We can even consider only a shot peening, grinding being practiced only to balance the propeller statically.

In summary, the propeller structure proposed by the invention reduces the times and costs of manufacturing the propellers, removes the currently most painful machining operations, and allows quality achievements, as regards dimensional precision, all by employing a less qualified workforce.

Furthermore, machined or semi-machined parts being kept in stock, and given the multiple possibilities offered by the standardization of parts, very short delivery times can be guaranteed to the user. This applies not only to the purchaser of a new propeller, but also has an undeniable advantage for the user in the event of damage to a propeller. It is then enough to replace the damaged blade or blades, which can be done in a very short time, and for a repair price much lower than currently, the user having in any case to change only the one or damaged blades, not the entire propeller.

While primarily targeting the production of fixed propellers, the invention makes it possible to adjust the pitch of the propeller, and this in an identical manner on all the points of each blade, the pitch thus being made truly adjustable. Adjustment of the propeller pitch can thus be done during manufacture, and also throughout the life of the propeller, which makes possi pitch corrections aimed at adapting the propeller to a thermal drive motor whose characteristics may change over time. The adjustment or adaptation of the pitch is very simple, since it suffices to loosen the locking screws to temporarily restore the blades' freedom of movement in rotation.

Finally, the proposed design, with blades attached to the hub, does not modify the external configuration of the propeller, so that the factors or parameters which are taken into account in determining the propeller are not affected by this design, that a propeller according to the invention can be easily mounted to replace a conventional propeller, and that on the aesthetic level also the appearance of the propeller is not modified at all.

• Figure 1 est une vue en perspective éclatée, c'est-à-dire avant montage des pales, d'une hélice de bateau conforme à la présente inven­tion ;
• Figure 2 est une vue en perspective de cette hélice dans son état définitif, après montage des pales;
• Figure 3 est une vue en demi-coupe passant par l'axe du moyeu de cette hélice, avec indication partielle de l'une des pales;
• Figure 4 est une demi-vue en coupe du moyeu seul, suivant la ligne IV-IV de figure 3;
• Figure 5 est une vue partielle et très schématique, montrant un détail des billes réalisant la liaison entre chaque pale et le moyeu;
• Figure 6 est une autre vue très schématique, indiquant une variante de la disposition des billes.

In any case, the invention will be better understood with the aid of the description which follows, with reference to the appended schematic drawing representing, by way of nonlimiting example, an embodiment of this propeller with added blades, as well as 'variant:

• Figure 1 is an exploded perspective view, that is to say before mounting the blades, of a boat propeller according to the present invention;
• Figure 2 is a perspective view of this propeller in its final state, after assembly of the blades;
• Figure 3 is a half-sectional view passing through the axis of the hub of this propeller, with partial indication of one of the blades;
• Figure 4 is a half sectional view of the hub alone, along the line IV-IV of Figure 3;
• Figure 5 is a partial and very schematic view showing a detail of the balls making the connection between each blade and the hub;
• Figure 6 is another very schematic view, indicating a variant of the arrangement of the balls.

The drawing represents a fixed boat propeller with three blades (1), mounted at regular angular intervals of 120 ° on a hub (2), the blades (1) being parts produced separately and attached to the hub (2) as shown. 'clearly shows Figure 1.

The hub (2) is provided with a passage (3) hollowed out along its axis (4) for mounting on a propeller shaft not shown. At the periphery of the hub (2) are formed three housings (5) of generally cylindrical shape; an annular groove (6), of semi-circular section, is machined in the cylindrical side wall of each housing (5).

Each blade (1) has a base (7), under which protrudes a head (8) of generally cylindrical shape, and of diameter corresponding to that of a housing (5). An annular groove (9), of semi-circular section, is hollowed out at the periphery of the head (8).

The mounting of each blade (1) on the hub (2) is carried out by introducing the head (8) into one of the housings (5), until the base (7) of the blade (1) comes to rest against the periphery of the hub (2). The annular groove (9) of the head (8) is thus placed in coincidence with the annular groove (6) of the housing (5), so that the two grooves (6, 9) together form a perfect toric cavity, as shown in Figure 3.

The connection between the blade (1) and the hub (2) is ensured by balls (10) introduced into the toric cavity formed by the two grooves (6, 9), so as to fill this entire cavity, the balls (10 ) being contiguous. These balls (10) are introduced into the toroidal cavity through a threaded hole (11) in the hub (2), parallel to the axis (4) which starts from an end face (12) of the hub (2) and opens into the throat (6).

The only balls (10) housed in the toric cavity leave the blade (1) the possibility of pivoting relative to the hub (2), in the manner of a ball bearing, which makes it possible to adjust the pitch of the 'propeller, or modify it. To block the blade (1) in rotation relative to the hub (2), an additional ball (13) is introduced into the tapped hole (11), and a locking screw (14) is tightened in this tapped hole (11) . As shown in FIG. 5, the thrust (P) of the screw (14) on the additional ball (13) causes the additional ball (13) to press between two balls (10) housed in the toric cavity. The additional ball (13) behaves like a wedge which pushes the balls (10) against each other, forces them to stagger and presses them alternately on the inner and outer surfaces of the toric cavity, that is ie on the bottoms of the two grooves (6, 9), which ensures total blockage by wedging. The additional ball (13) may have a larger diameter than that of the other balls (10), the threaded hole (11) being obviously dimensioned accordingly.

The locking screw (14) projecting slightly outside the hub (2), an internally threaded plug (15) is screwed onto the end of the screw (14) and pressed against the outer surface (12) of the hub ( 2), to brake the screw (14) by acting as a lock nut.

Opposite the tapped hole (11), a hole (16) is further drilled starting from the other end face (17) of the hub (2) and also opening into the toric cavity, at the bottom of the groove (6). . The hole (16) facilitates the evacuation of the balls (10) by blowing compressed air, or by admitting a liquid, or by introducing a rod. A screw cap (18) normally closes the entrance to the hole (16).

To reinforce the blocking of the blade (1) on the hub (2), and to identify the position of the blade (1) relative to the hub (2), two pins (19) are provided. Holes (20) are drilled in the base (7) of the blade (1), then counter-drilled in the hub (2) after adjusting the pitch, to receive the two pins (19) which, once put in place, rotate the blade (1) and the hub (2) _ see figure 3.

To ensure sealing, an annular seal (21) is provided mounted between the base (7) of the blade (1) and the hub (2), as well as two seals (22, 23) placed respectively at the inputs of the two holes (11, 16), in association with the plugs (15, 18).

All the internal cavities of the hub (2) are filled with thick grease, before sealing.

FIG. 6 shows a variant, making it possible to obtain stronger blocking of the balls, over the entire circumference. To this end, two diametrically opposite tapped holes 11 are provided, each receiving blocking means acting directly on the balls. These locking means can be constituted by two additional balls (13), on which the pressure of two respective locking screws (14) is exerted. It can also be provided that each tapped hole (11) receives a locking screw (14) terminated by a frustoconical end piece (24) and acting directly on the balls, during its tightening. The wedging effect can be further reinforced by providing that the balls introduced into the toric cavity include balls (10ʹ) of larger diameter and balls (10ʺ) of smaller diameter, the balls (10ʹ) of larger diameter alternating with the smaller diameter balls (10ʺ).

It goes without saying that the invention is not limited to the sole embodiments of this propeller with attached blades which has been described above, by way of example; on the contrary, it embraces all of the variant embodiments and applications respecting the same principle. In particular, the invention is in no way limited to fixed propellers with three blades, and it also applies to the production of variable pitch propellers, simply by eliminating or not using the locking system of each blade relative to the hub. The particular means for blocking the blades, described above in detail, can be replaced by any equivalent allowing the same essential advantages to be preserved. The design described can also be transposed to all rotating devices with blades, such as: turbine impellers, wind turbine rotors, rotary agitators with blades for liquids, mixer and mixer rotors, etc., which have a similar structure with a hub and blades, whether motor or receiver devices.

Claims (11)

1. Propeller or the like, such as turbine rotor, comprising a central propeller hub (2) at the peripheral portion of which are provided sockets (5) of generally cylindrical shape and blades (1) which are initially separated from the hub (2), each blade (1) having a base (7) with a part (8) of generally cylindrical shape complementary to and fittable in one of said sockets (5) of the hub (2), means being provided for fixing each blade (1) to the hub (2), said means comprising a first annular groove (6) of semicircular section formed in the cylindrical side wall of each socket (5) of the hub (2), a second annular groove (9) of semicircular section formed around the part (8) of the base (7) of the respective blade (1) which is complementary to said socket (5), the two grooves (6, 9) being aligned when said part (8) is fitted in the respective socket (5) thus defining an annular chamber, and balls (10) filling the annular chamber, characterized in that, in order to fix the blades (1) in the desired positions, said fixing means further comprises locking means (13,14) acting on the balls (10) for pressing said balls against each other and against the walls of the annular chamber formed by the two aligned grooves (6, 9).

2. Propeller or the like with joined blades according to claim 1, characterized in that the hub (2) is formed, at each cylindrical socket (5), with a passage (11) departing from the outer surface (12) of the hub (2) and opening into the annular groove (6) of the socket (5), the or each passage (11) being intended for introducing the balls ( 10) into the annular chamber and receiving then the locking means (13,14) which act on said balls (10).

3. Propeller or the like with joined blades according to claim 2, characterized in that said or each passage of the hub (2) is a threaded passage ( 11 ) housing another ball ( 13) and a blocking screw ( 14), the screwing of which presses the balls (10) of the annular chamber by means of said other ball ( 13).

4. Propeller or the like with joined blades according to claim 2, characterized in that said or each passage of the hub (2) is a threaded passage ( 11 ) housing a screw ( 14) having a frustoconical end (24) which, upon screwing, acts directly on the balls (10ʹ,10ʺ) filling the annular chamber.

5. Propeller or the like with joined blades according to claim 3 or 4, characterized in that a cap (15) with inner threads, acting as a retaining member for the screw, is screwed on the or each blocking screw (14) for the balls (10) and is pressed against the external surface (12) of the hub (2).

6. Propeller or the like with joined blades according to any of claims 3 to 5, characterized in that a seal ring (22) is provided at the mouth of each threaded passage ( 11 ) of the hub (2).

7. Propeller or the like with joined blades according to any of claims 2 to 6, characterized in that another passage (16) is provided extending from the external surface (17) of the hub (2) to the annular groove (6) of each cylindrical socket (5), for facilitating the removing of the balls (10) out of the annular chamber by effect of a fluid or by mechanical effect, means (18) being provided for normally closing said other passage (16) of the hub (2).

8. Propeller or the like with joined blades according to claims 6 and 7, characterized in that another seal ring (23) is provided at the mouth of said other passage (16) of the hub (2).

9. Propeller or the like with joined blades according to any of claims 1 to 6, characterized in that the hub (2) is formed, for each cylindrical socket (5), with two passages (11) which are diametrically opposite and are each housing locking means (14, 24) acting on the balls (10ʹ; 10ʺ) for pressing said balls against the walls of the annular chamber.

10. Propeller or the like with joined blades according to any of claims 1 to 9, characterized in that the balls housed in the annular chamber comprise first balls (10ʹ) of greater diameter and second balls (10ʺ) of smaller diameter, the balls (10ʹ) of greater diameter alternating with the balls (10ʺ) of smaller diameter.

11. Propeller or the like with joined blades according to any of claims 1 to 9, characterized in that at least one stop pin (19) is further provided for securing against relative rotation and in the desired angular relationship the base (7) of each blade (1) and the hub (2), the or each stop pin (19) being fitted into respective bores (20) extending through the base (7) of the blade (1) and the peripheral portion of the hub (2).

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