Torque boosting propeller device

Abstract

A propeller device for a marine vehicle with a main shaft; a front propeller is provided on the main shaft, the front propeller having a hub and a plurality of blades extending radially outwardly from the hub; a rear propeller being co-axially to and spaced from the front propeller, the rear propeller having a hub and a plurality of blades extending radially outwardly from the hub. A second shaft being communicated with the hub of the front propeller; and at least one support for supporting the rear propeller on the second shaft, the support prevents the second shaft to rotate in the direction of rotation of the main shaft, and being free to rotate thereof in the counter direction of rotation of the main shaft.

Claims

1. A propeller device for a marine vehicle, the propeller device comprising: a front propeller for mounting on a main shaft (3) communicating with a drive engine of the marine vehicle, the front propeller having a hub (1) and a plurality of blades (2) extending radially outwardly from the hub (1); a rear propeller being co-axially to and spaced from the front propeller, the rear propeller having a hub (4) and a plurality of blades (5) extending radially outwardly from the hub (4); a second shaft (6) fixedly communicating with the front propeller hub (1); at least one support (10) for supporting the rear propeller on the second shaft (6), the at least one support preventing the second shaft (6) from rotating in the direction of rotation of the main shaft (3) when the marine vessel travels in a forward direction and being free to rotate thereof in the counter direction of rotation of the main shaft (3) when the marine vessel travels in a backward direction.

2. A device according to claim 1, wherein the second shaft (6) comprises a flange (7) extending radially outwardly therefrom for communicating the second shaft (6) with the front propeller hub (1).

3. A device according to claim 1, wherein the rear propeller hub (4) comprises a substantially conical form.

4. A device according to claim 3, wherein a conical member (12) provided alongside with the rear propeller, the conical member (12) comprising a conical form being compatible with the conical form of the rear propeller hub (4).

5. A device according to claim 4, wherein the conical member (12) comprises a central through bore and a threaded part (20) formed on the surface of the bore, the threaded part (20) on the bore surface being constructed and arranged for engagement to the threaded part (19) of the second shaft (6).

6. A device according to claim 1, wherein the second shaft (6) comprises a threaded part (19).

7. A device according to claim 1, wherein the diameter of the rear propeller is smaller than the diameter of the front propeller.

8. A device according to claim 1, wherein the at least one support (10) is a ball bearing.

9. A device according to claim 1, wherein the rear propeller and the at least one support (10) can be replaceable with a bladeless intermediate conical member (22).

10. A marine vessel including a propeller device according to claim 1.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

(1) In order to understand the advantages of the present invention along with its embodiment and additional parts, it should be assessed together with the figures that are described in the following:

(2) FIG. 1 shows a perspective view of the propeller device according to the present invention;

(3) FIG. 2 shows the sectional perspective view of FIG. 1;

(4) FIG. 3 shows the side view of FIG. 2;

(5) FIG. 4 shows a sectional perspective view of the propeller device according to the present invention;

(6) FIG. 5 shows a side sectional view of the propeller device according to the present invention;

(7) FIG. 6 shows the rear view of the propeller device according to the present invention; and

(8) FIG. 7 shows the sectional view of the propeller device that is converted to a conventional propeller device.

DETAILED DESCRIPTION OF THE INVENTION

(9) While this invention may be embodied in many different forms, there are described in detail herein a specific preferred embodiment of the invention. This description is an exemplification of the principles of the invention and is not intended to limit the invention to the particular embodiment illustrated.

(10) The torque-boosting propeller device according to the present invention comprises a front propeller and a rear propeller being arranged co-axially with the front propeller. The front propeller comprises a front propeller hub (1) and a plurality of front propeller blades (2) extending radially outwardly therefrom. The rear propeller, similarly comprises a rear propeller hub (4) and a plurality of rear propeller blades (5) extending radially outwardly therefrom.

(11) The front propeller is rigidly mounted on a main shaft (3) connected to the engine of the marine vessel from one end. This connection is provided by screwing a nut (14) having a washer, on the inner part of which threads (18) are formed and which conforms with main shaft threads (17) that are formed on one end (i.e. the other end where the engine is not connected to) of the main shaft (3).

(12) The rear propeller is supported on a second shaft (6) by means of a support (10) being not rotatable in the direction of rotation and being free to rotate in the counter direction of rotation of the main shaft. The second shaft is coaxial with the main shaft (3). There is provided a space (11) inside the rear propeller hub (4) for receiving the support (10). The support (10) can be of any suitable support such as a ball bearing. As shown in FIG. 5, gaskets (21) can be arranged at lateral sides of the supports (10) for proofing water.

(13) The second shaft (6) comprises a flange (7) extending radially outwardly on the side of the front propeller hub (1). This flange (7) is preferably monolithic with the second shaft (6), and the flange (7) is communicated with the front propeller hub (1) by means of a plurality of shaft hub connection bolts (9) annularly screwed. There is provided a clearance between the rear propeller hub (4) and the flange (7) for a frictionless rotation of the rear propeller in case the support (10) is not locked. A recess (8) is formed on the inner part of the flange for receiving the threaded part (17) of the main shaft. The external form of the rear propeller hub (4) has substantially a conical form so that the water resistance created thereon is minimized.

(14) A conical member (12) is mounted alongside with the rear part of the rear propeller so as to decrease the water resistance. The external form of the conical member (12) is so designed that it will taper towards the end in accordance with the conical form of the rear propeller hub (4). The second shaft (6) has a threaded part (19), likewise, the conical member (12) having a central through bore, has a threaded part (20) on the bore surface, which are compatible with the threaded part (19) of the second shaft (6). For mounting the conical member (12) to the second shaft (6), threaded parts (19, 20) are screwed and then the conical member (12) is tightened by a wrench inserted through the end (16) of the conical member (12). Connection security of the conic member (12) is provided by means of a bolt (13) penetrating radially into a groove formed on the conical member (12) and the second shaft (6). There is provided a clearance between the rear propeller hub (4) and the conical member (12) for providing a frictionless rotation of the rear propeller.

(15) In operation, water going out of the rear side of the front propeller is accelerated by means of the blades (2) of the front propeller, and this high-speed water hits the rear propeller blades (5) rotating the rear propeller. As the support (10) is locked in the rotational direction of the main shaft (3), torque created with the effect of the water hitting the rear propeller blades (5) is exerted on the second shaft (6) in the rotation direction of the main shaft (3). As the front propeller is accelerated, the rear propeller rotates faster because of the water energized by the front propeller, and the rotation speed of the second shaft (6) thus becomes higher than that of the main shaft (3). As the second shaft (6) is connected to the front propeller hub (1) by means of its flange (7), the torque created on the second shaft (6) is transmitted to the front propeller hub (1). Therefore, the torque provided to the front propeller by the vessel engine, so as to thrust the marine vessel decreases, which provides a better propeller thrust with less fuel consumption.

(16) When the marine vessel navigates rearward, the main shaft rotates in the reverse direction, the support (10) will be free to rotate, providing an idle rotation of the rear propeller. Therefore, the rear propeller does not drag on water.

(17) The propeller device according to the present invention can be converted into a conventional monolithic structure without having the rear propeller. As shown in FIG. 7, this is achieved by removing the rear propeller and the supports (10), and a bladeless intermediate conic member (22) is mounted in place of the removed components. The inner part of the intermediate conic member (22) comprises a stepped cavity in a way that it preferably fits tightly on the flange (7) and the second shaft (6); or fits thereon then by means of a wedge connection as per appreciated by those in the art.

(18) On the other hand, the propeller device according to the present invention can be applied to a conventional propeller, i.e. having a single propeller, in particular, when a single propeller becomes heavy for the marine vessel because of the high pitch thereof. In other words, the propeller device of the invention can be applied to a propeller which cannot receive enough torque from the main shaft. This is achieved by incorporating a rear propeller on the rear part of the high-pitch propeller.

(19) As is shown in FIG. 6, the diameter of the rear propeller is preferably smaller than that of the front propeller.

(20) This completes the description of the preferred and alternate embodiments of the invention. Those skilled in the art may recognize other equivalents to the specific embodiment described herein which equivalents are intended to be encompassed by the claims attached hereto.