Flange interface for a marine drive unit and marine drive unit

Abstract

The present invention relates to a flange interface (1 ) to be mounted between an upper part (2) and a lower part (3) of a marine drive unit (100). The flange interface (1 ) comprises a body (4) to be fixed to a flange (5) surrounding an opening in the bottom of a boat hull (6) and the body (4) comprises an exhaust gas passage (7). The exhaust gas passage (7) comprises an outlet (8) to guide the exhaust gas into the water invention relates further to a marine drive unit (100) with such a flange interface (1 ).

Description

[0001] The present invention relates to a flange interface for a bottom-mounted marine drive unit and to a corresponding marine drive unit. The marine drive unit extends through an opening in the bottom of the hull. Such a marine drive unit is also called a POD-drive.

[0002] A POD-drive usually has an upper part which is stationary mounted inside a boat hull and a lower part which is rotatable mounted at the outside the bottom of the hull. The lower part supports a propeller shaft. A propeller is mounted to one end of the propeller shaft and imparts a propulsive thrust in the water during operation. A flange interface is arranged between the upper part and the lower part. The flange interface serves for different purposes. It is used to mount the marine drive unit to the bottom of the hull and to seal off the opening in the bottom of the hull. In some POD-drives the flange interface comprises an exhaust gas passage to guide the exhaust gas from an engine inside the hull from the upper part through the lower part to an outlet at the propeller.

[0003] One example of a marine drive unit with such a bottom-mounted flange interface has been disclosed in US 7,387,556 B1. This document describes a bottom-mounted marine drive unit comprising an upper part, which is stationary mounted inside a boat hull, and a lower part, which is rotatable mounted beneath the upper part. A midsection in form of a flange interface is arranged between the upper part and the lower part. The lower part supports a propeller shaft which can be driven by a drive shaft extending from the upper part into the lower part. An exhaust passage is arranged to lead the exhaust gas from the upper part through the midsection and through the lower part to an outlet which is arranged at a propeller. Another example of a flange interface for a bottom-mounted marine drive unit has been disclosed in US 2007 / 270053 A1.

[0004] The purpose of the present invention is to provide a bottom-mounted marine drive unit and a flange interface for such a drive unit which is easy to install into a boats hull and allows for a robust and multifunctional design of the marine drive unit.

[0005] These purposes are achieved by a flange interface according to claim 1 and by a marine drive unit according to claim 7. Further preferred embodiments are claimed in dependent claims.

[0006] The present invention provides a flange interface to be mounted between an upper stationary part and a lower rotatable part of a marine drive unit. The upper part can be stationary mounted inside the hull of a boat. The lower part is rotatable mounted outside the hull. The flange interface comprises a body to be fixed to a flange surrounding an opening in the bottom of a boat hull. The body comprises an exhaust gas passage with an outlet to guide the exhaust gas from the engine inside the hull into the water. The exhaust gas outlet directly into the water provides different advantages. This way the exhaust gas does not have to pass through the lower part of the marine drive unit with significant section changes. Hence, a simple design of the marine drive unit and a low pressure drop in the exhaust gas stream can be achieved. The lower part of the marine drive unit can be streamlined with a very slim design without the need for an exhaust gas passage. The present invention can be used in marine drive units or POD-drives with one or two propellers.

[0007] The body of the flange interface comprises a protrusion to protrude the lower part of the marine drive unit in a reverse direction. The outlet is arranged at the protrusion, so that the outlet is not covered by the lower part. With other words the outlet is located behind the lower part with regard to a forward heading direction. This feature helps to avoid any adverse effects to the propulsion efficiency of the propeller or the propellers, as the exhaust gas can easily be guided into the water in a safe distance to the propellers. Therefore, the flange interface according to the present invention may be used in marine drive units with pulling or pushing propellers. Pushing propellers means that the propellers are located behind the lower part of the marine drive unit while pulling propellers are located in front of the lower part with regard the forward heading direction.

[0008] A scoop can be arranged at the outlet. The scoop can be mounted beneath the outlet and cover the outlet at least partially. Such a scoop can have different sizes and shapes. The shape of the scoop may define the cross section for the exhaust gas flow at the outlet. This gives the possibility to manage different engine applications with different exhaust flows. Preferably the scoop has a streamlined shape to minimize drag effects in the water. It can be made of sheet metal for example. A sealing can be positioned between the flange interface and the scoop. The sealing can damp vibrations caused by pulsating waves of the propeller. By means of the scoop with the vibration damping sealing a counterpressure effect in the exhaust passage can be optimized.

[0009] Another aspect of the invention regards the robustness and stiffness of the marine drive unit. In order to enhance the stiffness, one embodiment comprises a fixing frame to be connected to the body, thereby fixing the marine drive unit to the flange in the bottom of the hull. By means of the fixing frame and its connection with the body, the flange interface can be fastened to the hull without the need to drill the hull. Instead the present invention provides a sandwich nested flange interface which enables a very stiff and robust connection of the marine drive unit and the hull. Such a connection makes the flange interface more integral with the hull structure and simplifies the assembly. The flange in the bottom of the hull can be a structural part of the hull by connecting the flange with stringers or other frame parts of the hull. Hence, the whole sandwich flange unit is very robust, especially against damages caused by ground contact of the lower part of the marine drive unit.

[0010] The body of the flange interface has a contact surface which comes into contact with the flange of the hull. The contact surface may have at least partially a conical shape. The conical shape enables a save and reliable connection to a corresponding flange surface in the bottom of the hull. The contact surface may comprise at least one recess to hold a first sealing element. A first sealing element, for example a sealing ring, can be easily arranged in the recess and allows a quick and correct mounting of the flange interface together with the sealing into the hull. The recess ensures the correct positioning of the sealing during and after assembly. Further sealing elements like sealing rings can be arranged at the flange interface to avoid water intrusion into the hull.

[0011] The present invention relates further to a marine drive unit comprising a flange interface as described above. Such a marine drive unit comprises an upper part to be stationary fixed inside a hull of a boat, a lower part to be rotatably arranged beneath the hull and a flange interface which is arranged between the upper part and the lower part. The main task of the flange interface is to securely fasten the marine drive unti to a flange at an opening in the bottom of the hull and to seal the opening against water intrusion.

[0012] The invention will be further and more particularly described in the following, by way of example only, and with reference to the accompanying drawings, in which: Fig. 1shows a schematic drawing of a marine drive unit according to the present invention; Fig. 2shows a perspective view on a flange interface according to the invention and Fig. 3shows a full section view of the flange interface in Fig. 2.

[0013] Fig. 1 shows a bottom-mounted marine drive unit 100, also known as a POD-drive. It is mounted to a hull 6 of a boat. The marine drive unit 100 comprises an upper part 2, a lower part 3 and a flange interface 1, which is arranged between the upper part 2 and the lower part 3. The marine drive unit 1 can be driven by an engine 10 which is also arranged and supported inside the hull 6. The engine 10 is connected to the upper part 2. An output shaft 16 of the engine 10 is connected to an input shaft 17 at the upper part 2. The upper part 2 of the marine drive unit 1 is stationary positioned inside the hull 6 of a boat. The upper part 2 comprises a gearbox with a first bevel gear 18 to transmit the propulsion power from the horizontal input shaft 17 to a drive shaft 19 which is arranged vertically inside the marine drive unit 100. The drive shaft 19 runs from the upper part 2 through an aperture 20 in the flange interface 1 into the lower part 3.

[0014] The lower part 3 of the marine drive unit 1 is mounted rotatable beneath the hull 6. This means it can pivot about a vertical axis which coincides at least roughly with the rotation axis of the drive shaft 19. Rotation of the lower part 3 can be effected by a steering drive which can be positioned inside the upper part 2. of the pivotability of the rotational axis of the propellers, a steering effect of the boat is produced. A second bevel gear 21 transfers the drive power from the vertical drive shaft 19 to a horizontally arranged propeller shaft 22. A propeller 23 is fixed to the free end of the propeller shaft 22.

[0015] The flange interface 1 is mounted between the upper part 2 and the lower part 3. The body 4 of the flange interface 1 is fixed to a flange 5 of the hull 6. The flange 5 surrounds an opening in the bottom of the hull 6. The flange 5 can be connected or integrated in the basic structure of the hull 6, in order to achieve a maximum stiffness of the arrangement.

[0016] The body 4 of the flange interface 1 comprises an exhaust gas passage 7. An outlet 8 of the exhaust gas passage 7 guides the exhaust gas directly into the water. There is a protrusion 9 of the body 4, which protrudes the lower part 3 of the marine drive unit 100 in a reverse direction. The outlet 8 of the exhaust gas passage 7 is arranged at the protrusion 9.

[0017] More details of the flange interface 1 can be seen in Fig. 2 and Fig. 3. The flange interface 1 has got an oblong shape to be inserted in a corresponding oblong opening in the bottom of the hull 6. The flange interface 1 is prepared for a so-called sandwich nested flange installation in the hull 6. Therefore, the flange interface 6 comprises a fixing frame 11 to be connected to the body 4, thereby clamping the flange interface 6 to the flange 5 in the bottom of the hull 6. The fixing frame 11 is basically a plate-shaped metal frame. To mount the flange interface 1 to the hull 6, the fixing frame 11 can be screwed to the upper side of the body 4, thereby clamping the flange 5 of the hull 6 between the fixing frame 11 and the body 4. The body 4 has ribs 25 to reinforce the structure of the flange interface 1 and to achieve a high stiffness of the whole arrangement in the hull 6.

[0018] The body 4 has a contact surface 12 around its outer side to be in contact with the flange 5 in the bottom of the hull 6. The contact surface 12 has a shape which corresponds to the shape of the inside of the flange 5. The contact surface 12 comprises a recess 13 to hold a first sealing element 14 in order to achieve a watertight connection between the body 4 and the flange 5. Another recess with a second sealing element 24 is provided at the lower side of the body 4.

[0019] As can be seen in Fig. 3 there is a scoop 15 fixed to the flange interface 1 at the outlet 8.Referals

[0020] 1flange interface 2upper part 3lower part 4body 5flange 6hull 7exhaust gas passage 8outlet 9protrusion 10engine 11fixing frame 12contact surface 13recess 14first sealing element 15scoop 16output shaft 17input shaft 18first bevel gear 19drive shaft 20aperture 21second bevel gear 22propeller shaft 23propeller 24second sealing element 25rib 100marine drive unit

Claims

1. Flange interface (1) to be mounted between an upper part (2) and a lower part (3) of a marine drive unit (100), wherein the flange interface (1) comprises a body (4) to be fixed to a flange (5) surrounding an opening in the bottom of a boat hull (6), wherein the body (4) comprises an exhaust gas passage (7), wherein the exhaust gas passage (7) comprises an outlet (8) to guide the exhaust gas into the water, wherein, when mounted, the body (4) comprises a protrusion (9) to protrude over the lower part (3) of the marine drive unit (100) in a reverse direction, characterized in that the outlet (8) is located behind the lower part (3) with regard to a forward heading direction and in that the outlet (8) is arranged at the protrusion (9), so that the outlet (8) is not covered by the lower part (3).

2. Flange interface (1) according to claim 1, wherein a scoop (15) is arranged at the outlet (8).

3. Flange interface (1) according to one of the preceding claims, wherein the flange interface (1) comprises a fixing frame (11) to be connected to the body (4), thereby fixing the marine drive unit (100) to the flange (5) in the bottom of the hull (6).

4. Flange interface (1) according to one of the preceding claims, wherein the body (4) has a contact surface (12) to be in contact with the flange (5) in the bottom of the hull (6), and wherein the contact surface (12) has at least partially a conical shape.

5. Flange interface (1) according to claim 4, wherein the contact surface (12) comprises at least one recess (13) to hold a first sealing element (14).

6. Marine drive unit (100) comprising an upper part (2) to be stationary fixed inside a hull (6) of a boat, a lower part (3) to be mounted rotatable beneath the hull (6) and a flange interface (1) which is arranged between the upper part (2) and the lower part (3), characterized by a flange interface (1) according to one of the preceding claims.

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