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EP-4741280-A1 - NAUTICAL PROPELLER

EP4741280A1EP 4741280 A1EP4741280 A1EP 4741280A1EP-4741280-A1

Abstract

Propeller (1) comprising a cylindrical body (3), a hub (2) able to be coupled to a drive unit and rotatably assembled at least partially in said cylindrical body of the propeller, and at least one blade (4) rotatably pivoted to said cylindrical body of the propeller, said hub (2) being rotatable relative to said cylindrical body of the propeller, or vice versa, for adjusting the fluid dynamic pitch of said at least one blade (4), the propeller further comprising at least one elastic element (8) for adjusting the fluid dynamic pitch of said at least one blade and an adjusting device (30) for adjusting at least the preload of said at least one elastic element (8), characterized by comprising at least one housing body (14a, 14b) interposed between said elastic element (8) and said cylindrical body (3), said elastic element (8) being housed in said housing body (14), said housing body (14a, 14b) being rotatable relative to said cylindrical body (3).

Inventors

  • BIANCHI, MASSIMILIANO

Assignees

  • Max Prop S.r.l.

Dates

Publication Date
20260513
Application Date
20251010

Claims (12)

  1. Propeller (1) comprising a cylindrical body (3), a hub (2) couplable to a drive unit and rotatably assembled at least partially in said cylindrical body of the propeller, and at least one blade (4) rotatably pivoted to said cylindrical body of the propeller, said hub (2) being rotatable relative to said cylindrical body of the propeller, or vice versa, for adjusting the fluid dynamic pitch of said at least one blade (4), the propeller further comprising at least one elastic element (8) for adjusting the fluid dynamic pitch of said at least one blade (4) and an adjusting device (30) for adjusting at least the preload of said at least one elastic element (8), characterized by comprising at least one housing body (14a, 14b) interposed between said elastic element (8) and said cylindrical body (3), said elastic element (8) being housed in said at least one housing body (14a, 14b), said housing body (14a, 14b) being rotatable relative to said cylindrical body (3).
  2. Propeller according to claim 1, comprising a pair of housing bodies (14a, 14b) arranged opposite each other relative to a plane perpendicular to the axis of rotation of the hub.
  3. Propeller according to claim 1 or 2, wherein each housing body (14a, 14b) has a substantially annular shape around the elastic element.
  4. Propeller according to one of the preceding claims, configured so that said adjusting device (30) is provided with a travel, so that in a first portion of said travel, said adjusting device pushes said elastic element, which in turn pushes said hub to rotate relative to said cylindrical body so as to vary the fluid dynamic pitch of said at least one blade (4), and in a second portion of said travel said adjusting device continues to push against said elastic element, the relative rotation between said hub and said cylindrical body being prevented, so as to compress said elastic element between said adjusting device and said cylindrical body (3), so as to cause the preload of said elastic element to be increased.
  5. Propeller according to one or more of the preceding claims, wherein said cylindrical body (3) comprises a seat (3a) for said adjusting device, which protrudes inward from the rest of the cylindrical body (3).
  6. Propeller according to one of the preceding claims, comprising at least one end-stop body (15a, 15b) for the elastic element (8), preferably a pair of end-stop bodies (15a, 15b), each end-stop body being rotationally integral with the cylindrical body (3) and being arranged to define the end-stop position for the end of the elastic element opposite the preload modifying device (30).
  7. Propeller according to any one of the preceding claims, wherein said adjusting device (30) is in the form of one or more screws extending through said cylindrical body (3) of the propeller.
  8. Propeller according to one or more of the preceding claims, wherein each housing body (14a, 14b) is arranged laterally to said adjusting device (30), on at least one plane comprising the axis of rotation of the hub.
  9. Propeller according to one or more of the preceding claims, comprising a cavity (16) between the at least one cylindrical body of the propeller (3) and the at least one housing body (14a, 14b).
  10. Propeller according to any one of the preceding claims, comprising an intermediate thrust element (11) interposed between said hub (2) and said housing body (14a, 14b) and configured so that a relative rotation between said hub (2) and said cylindrical body (3) causes said intermediate element (11) to compress the elastic element (8), which is preferably provided with a cavity defining an angular range of free rotation of said hub (2) relative to said cylindrical body (3) of the propeller.
  11. Propeller according to one or more of the preceding claims, comprising, at least at said elastic element (8) and/or at the coupling between hub and propeller body at the front portion of the propeller, elements (201, 202) having complementary portions (203, 204, 205), so as to form a labyrinth path (200; 250) for containing lubricants.
  12. Method of using a propeller (1) according to any one of the preceding claims, rotationally coupled to a drive unit, wherein a preload of said elastic element is equal to or greater than zero and is provided by said preload modifying device (30), wherein when the thrust (F2) of the hub (2) exceeds the preload (F1) of the adjusting element (30), a compression of the elastic element (8) within said at least one housing body (14a, 14b) takes place, thus causing a relative rotation between said hub (2) and said cylindrical body (3), which in turn causes the pitch of said blade (4) to be changed.

Description

FIELD OF THE INVENTION The present invention concerns to a propeller, preferably for nautical use, and a respective use method, in which the blades can be arranged at the fluid dynamic pitch most suitable to the various propeller operation conditions. It is well known that, to achieve ideal conditions with optimal efficiency at every stage of navigation, the arrangement of the propeller blades must adopt and maintain the correct fluid dynamic pitch in each individual stage, that is, adopt and maintain a proper and suitable angle of attack relative to the fluid they encounter. Specifically, the operation of the propellers used in nautical propulsion can be subdivided into three main stages, which follow each other as the navigation speed of the vessel increases. The first stage of the propeller operation, which usually corresponds to the minimum navigation speed, is when the vessel's maneuvers are carried out. The second stage of operation, in which the navigation speed increases from the first stage, is usually used for cruising navigation. The third stage of operation, identifiable by a further increase in navigation speed until the maximum rotation speed of the drive unit is reached, is when the vessel is propelled up to the maximum navigation speed. PRIOR ART In conventional fixed-pitch propellers, known in the art, the fluid dynamic pitch of the blades is sized according to the power supplied by the drive unit at the maximum rotation speed of the drive unit on which the propeller is to be installed. The so sized propeller will only be able to provide good efficiencies in the first and third stages of operation. De facto, as mentioned above, the pitch of the conventional fixed propeller is sized precisely to achieve the best efficiency in the third stage, that is, with the maximum navigation speed and the maximum propeller rotation speed. Maximum speed can only be achieved with small pitches. Even in the maneuvering stage (first phase), a small pitch does not give rise to any drawbacks (it is rather advantageous instead) since no performance in navigational speed is required in this stage, but only readiness to respond to commands given by the maneuverer. On the other hand, a small pitch is very disadvantageous in the second stage of operation, that is to say in cruising navigation, this stage being, as known, of great importance as it is by far the most used. In the second stage, a small fixed pitch will result in low efficiency of the propeller, and the power supplied by the drive unit will not be effectively converted into propulsive thrust. In order to ensure high efficiency during cruising navigation (a stage with medium values of rotation speed), it is essential to arrange the propeller blades with a high fluid dynamic pitch. To meet these needs, propellers have been developed in which the relative angle of rotation of the hub relative to the propeller body, and vice versa, can be varied during navigation. This variation is achieved by a dedicated known kinematic system. In particular, it is known to equip a propeller with a specifically shaped elastic element which adjusts the relative rotation of the hub relative to the propeller body, and consequently the propeller pitch, during the operation of the propeller itself, as described, for example, in Patent Application WO2018065800 (hereinafter also referred to as WO'800), in the name of the Applicant. Specifically, such a propeller is equipped with a device described in WO'800 (which is also schematically depicted in Figure 1 which refers to the known art) that allows the navigation of a vessel to be made more efficient, particularly during the cruising stage. A propeller of this type allows high navigation speed to be achieved at a medium/low engine rotation speed. From now on, the rotation speed is referred to as "RPM" (number of revolutions per minute). The device of WO'800 allows the propeller to absorb and convert, into thrust for the vessel, a significantly higher portion of the power available to the engine compared to the power portion that is absorbed and converted into thrust by using a conventional fixed-pitch propeller at the same RPM. Therefore, the device of WO'800 advantageously allows high navigation speeds to be achieved at medium RPMs. Referring to Figure 1, which relates to the known art described in Patent Application WO'800, the power portion available to the engine (which the propeller is able to absorb and convert into thrust for the vessel) generates a driving torque which is equal and opposite to the torque countering the rotation of the propeller. Said driving torque generates the thrust F2, which is transmitted to the elastic element 101 housed in the propeller body. The device according to the known art provides that an element for adjusting the preload of the elastic element 101, such as a screw 103, is inserted into the propeller body 102. By means of such an adjusting element, for example by means of such a screw 103,