Propulsion of a watercraft

Abstract

The invention relates to a propulsion system (1) for a watercraft, which is designed as a pump jet and has a housing (10) with at least one inlet channel (14) and at least one outlet nozzle (15) communicating therewith, and a propeller arranged between the at least one inlet channel (14) and the at least one outlet nozzle (15) and designed as an impeller (13) and rotatable via a drive motor, by means of which propeller water is sucked into the housing (10) via the inlet channel (14), accelerated, and expelled from the housing via the outlet nozzle (15) as a thrust jet, wherein the housing (10) is rotatable about a control axis (S) by means of a control drive, and the drive motor comprises an annular stator (11) fastened in the housing (10) and a rotor (12) received therein, which forms the impeller (13),wherein the housing (10) comprises a fixed inner part (100) and an outer part (101) mounted on the inner part (100) so as to be rotatable about the control axis (S), and the stator (11) is fixedly connected to the inner part (100) via retaining struts (102).

Description

[0001] The invention relates to a propulsion system for a watercraft which is designed as a pump jet and has a housing with at least one inlet channel and at least one outlet nozzle communicating therewith and a propeller arranged between the at least one inlet channel and the at least one outlet nozzle and designed as an impeller and rotatable via a drive motor, by means of which water is sucked into the housing via the inlet channel, accelerated and ejected from the housing as a thrust jet via the outlet nozzle,

[0002] Such pump jet propulsion systems for watercraft are widely known and, due to their mode of operation, are also referred to as waterjet propulsion. This is a propulsion unit with a recoil drive for a wide variety of applications, for example in special vessels and rescue units, but also in amphibious military vehicles and submersible underwater vehicles. High-speed, lightweight gasoline or diesel engines or gas turbines drive an impeller—a shrouded propeller—that draws water in from beneath the hull and expels it through movable discharge nozzles. Waterjet propulsion using a pump jet enables efficient vector control by pivoting the discharge nozzle in the direction the watercraft is to turn. Reverse travel is also possible in this way.Compared to traditional propeller-driven watercraft, jet-driven watercraft can be built and operated extremely flat and are extremely maneuverable even at the slowest speeds.

[0003] Such a pump jet water jet propulsion system for a watercraft is known from the generic WO 2009 / 071077 A2, the inlet and outlet channels of which are arranged in a housing that can rotate about the steering axis and also acts as a diffuser. To create a particularly compact design, the drive motor is formed by a magnetic motor integrated into the housing. The motor comprises an annular stator and a rotor, also annular, rotating therein, which also forms the impeller. However, since the stator is arranged within the rotatable housing, its power supply must be effected via slip rings in the area of ​​the housing bearings. This is extremely cost-intensive and, due to the design of sliding contacts, is susceptible to wear, particularly in the presence of vibrations, which are inevitably present during ship operation.

[0004] DE 199 05 141 A1, on the other hand, discloses a pump jet waterjet propulsion system whose impeller is driven by a drive motor located in the hull via a drive shaft extending from the housing into the ship's hull and an angle drive. The housing has a part firmly connected to the hull in the area where the drive shaft passes, and a sealed part that rotates around the steering axis and also houses the outlet nozzle of the thrust jet. Such a propulsion system is structurally very complex and requires a large amount of space due to the shaft drive and the drive motor located in the hull, which is extremely disadvantageous.

[0005] The object of the invention is to propose a drive of the type mentioned at the outset which overcomes the disadvantages of the prior art.

[0006] The problem is solved by a drive of a watercraft according to claim 1.

[0007] According to the invention, the housing is thus designed in two parts and comprises a stationary inner part and an outer part that can be rotated about the control axis to maintain the control function. The stator of the magnetic motor provided according to the invention is fixed to the inner part via retaining struts and, like the inner part, is arranged in a stationary and fixed manner. Nevertheless, the rotor is arranged so as to be freely rotating in the stator and the outer part can be rotated about the control axis relative to the stationary inner part by means of the control drive in order to ensure the control function of the drive according to the invention, which is designed as a pump jet. Since, according to the invention, the inner part and the stator are firmly connected to one another via the retaining struts, there is no longer any need to ensure the energy supply to the stator via complex and defect-prone slip rings.

[0008] According to a proposal of the invention, it is particularly provided that the electrical connection lines of the stator and, if applicable, control lines, sensor lines, etc. run along or within the support struts from the inner part to the stator, which is why the support struts are preferably designed as a hollow profile.

[0009] According to a further proposal of the invention, the inner part comprises a deflection arch for reversing the flow direction of the water sucked in by the impeller via the inlet channel and accelerated in the direction of the at least one outlet nozzle, and the support struts run between the deflection arch and the stator.

[0010] In addition to the stationary fixation of the stator to the inner part and the guidance of the connecting lines leading to the stator, according to a further proposal of the invention the support struts can also be shaped or provided with such a flow profile that they counteract the swirl induced in the accelerated water by the impeller. Typically, the rotating impeller, which conveys the water jet, imparts a corresponding swirl to the accelerated water due to its rotational movement, which leads to a loss of efficiency. By appropriately designing the surface of the support struts around which the accelerated water flows as it passes through the housing, this swirl can be counteracted, i.e. the accelerated water jet is de-swirled by the support struts, which can significantly increase efficiency.

[0011] For this purpose, the support struts can be arranged at equal or different distances from each other, depending on requirements, and can have the same or different cross-sections. For example, some support struts can be larger to accommodate the connecting cables leading to the stator, as well as any control and measurement cables, while other support struts can be given a special contour to their surfaces to de-swirl the accelerated water jet.

[0012] In one possible embodiment of the invention, the outer part of the housing, which is rotatable about the control axis, comprises the at least one inlet channel and the at least one outlet nozzle, which are preferably arranged radially to the outer part and are arranged opposite one another with respect to the control axis.

[0013] Alternatively, it is also possible to arrange the inlet channel and / or the outlet channel in the area of ​​the underside of the pump jet in a conventional manner. The outlet channel is preferably always integrated into the outer part to achieve the desired rotation around the control axis for controlling the thrust jet.

[0014] According to a further proposal of the invention, the impeller is rotatably mounted on a fixed shaft attached to the inner part, thus ensuring a particularly simple mechanical design. The bearing can be encapsulated and requires only dynamic sealing against seawater. Alternatively, the impeller can also have a shaft or shaft stub projecting toward the inner part, which is rotatably mounted in the fixed inner part.

[0015] Depending on the application, the drive according to the invention can be permanently installed on or in a ship's hull or can be designed as an extendable drive which, when installed in a hull of a watercraft, can be moved between a retracted rest position and an extended working position, wherein the drive can be extended in the extended working position to such an extent that the at least one inlet channel and the at least one outlet nozzle protrude beyond the hull of the watercraft.

[0016] The connection of the drive according to the invention to the hull of a watercraft can be achieved, for example, by connecting the inner part to a flange for fixation in the watercraft. Due to the fixed arrangement of the inner part, the flange can be firmly connected to the hull of the watercraft, for example, by screwing it. Furthermore, it is also possible to fix the flange to the watercraft using elastically flexible shock bearings in order to minimize running noise and / or to make the drive resistant to external shock loads.

[0017] Further embodiments and details of the drive according to the invention are explained below with reference to the drawing which shows an exemplary embodiment.

[0018] The single figure shows a perspective view of a section through a propulsion system 1 of a watercraft designed as a pump jet, which generates a thrust jet emerging from an outlet nozzle 15, which generates propulsion and a steering moment for the watercraft equipped therewith.

[0019] The drive 1 comprises a housing 10 with several inlet channels 14 for water sucked in from outside the hull, which then enters an anteroom 140 arranged within the housing 10.

[0020] Above the antechamber 140 there is arranged a vertically oriented propeller in the form of an impeller 13 which is set in rotation by a drive motor which will be explained in more detail below and by means of its propeller blades not only causes the water to be sucked into the antechamber 140 via the inlet channels 14, but also accelerates the water from the antechamber 140 vertically upwards in the direction of a deflection arch 16, along which the accelerated water jet is reversed in the flow direction indicated by arrows and flows downwards in the direction of the outlet nozzle 15 which is arranged diametrically opposite the inlet channels 14 and via which the water jet is then ejected from the drive 1.

[0021] The housing 10 of the drive 1 is divided into an inner part 100 and an outer part 101, wherein the inner part 100 is fixed in a fixed and stationary manner in the hull of the watercraft (not shown here) via a flange 18 in a manner not shown in detail, for example screwed, and is thus fixed in position.

[0022] In contrast, the outer part 101 is sealed from the inner part 100 by seals 105, 103 acting on both sides, but is freely rotatable about the vertically extending control axis S by means of a drive motor 17 in order to endlessly rotate the outlet nozzle 15 into any orientation about the control axis S in a manner known per se and to generate control impulses for the thus equipped watercraft by means of the drive 1. Between the inner part 100 and the outer part 101, a circumferential annular gap 104 is present, which ensures the free rotation of the outer part 101 relative to the stationary inner part 100, wherein the annular space 106 formed between the inner part 100 and the outer part 101 behind the annular gap 104 is sealed by the gap seal 103. In this area, relief bores leading radially outwards can also be arranged to bring about pressure relief in this area.

[0023] An essential feature of the drive 1 shown is that the drive motor of the impeller 13 is formed by a magnet or induction motor arranged entirely within the housing 10, which comprises a fixed annular stator 11 and a rotor 12 which is also annular and rotates within the fixed stator 11 and at the same time forms the impeller 13.

[0024] The stationary and thus stationary annular stator 11 is fastened to the deflection arch 16 of the likewise stationary inner part 100 of the housing 10 via a plurality of support struts 102, wherein the electrical connection lines for the winding system of the stator 11 and the sensors of the stator 11 are led through the support struts 102, which are designed as a hollow profile, to the inner part 11 and from there out of the flow space, so that the drive 1 does not require slip rings or the like, since the lines are guided exclusively through stationary components of the drive.

[0025] The rotor 12, however, which carries the propeller blades of the impeller 13, is rotatably mounted with a centrally formed hub on a rigid axle 108 projecting downwards on the inner part 100, which results in a particularly robust and wear-resistant arrangement of the impeller 13 in the housing 10. The bearing of the hub on the axle 108 can be encapsulated and requires only a dynamic seal above it against seawater.

[0026] Since a rotating impeller 13 inevitably imparts a corresponding swirl to the water jet conveyed and accelerated by it, which leads to efficiency losses, the support struts 102 around which the accelerated water jet flows can have a profile or cross-sectional design and orientation such that they not only allow the passage of the connection and control lines for the stator 11, but also impart a flow direction to the water jet that opposes the swirl, thus overall de-swirling the water jet conveyed and accelerated by the impeller 13. Thus, the pressure of the thrust jet generated in the drive 1 can be maximized and, at the same time, the required control torque of the control drive 17 for rotating the outer part 101 about the control axis S during ongoing operation of the impeller 13 can be minimized.

[0027] To increase the pressure, the housing 10 can also be designed as a diffuser. The diffuser can be designed as in Fig. 1 or can also be designed as a ring diffuser.

[0028] In addition to the particularly compact and wear-resistant design, the drive described above offers a further advantage in that it requires very little oil volume, so that the required size of a pressure transmitter, for example, can be reduced to less than 10 l of oil volume.

[0029] In addition to a rigid connection of the flange 18 to the hull of the watercraft (not shown here), this can also be carried out with the interposition of shock bearings in order to increase the resistance of the drive 1 against external shock waves.

[0030] Due to the integration of the drive motor within the housing 1, the space gained above the housing 1 can be used, in comparison to conventional pump jets, to arrange a travel mechanism there, which consists, for example, of synchronous cylinders that are controlled by a pump arranged in the possibly pressure-neutral oil-filled interior, in order to move the drive as needed from a retracted rest position to an extended working position, wherein the drive is extendable in the extended working position so far that the at least one inlet channel 14 and the at least one outlet nozzle 15 protrude beyond the hull of the watercraft, while in the retracted rest position piston rods acted upon by seawater are retracted and protected from growth and no change in volume occurs.

[0031] The drive system described above is suitable for integration into a wide range of watercraft and, due to its small size, can also be retrofitted to corresponding watercraft. List of reference symbols: 1 drive 10 housings 11 Stator 12 Rotor 13 impellers 14 Inlet channel 15 Outlet nozzle 16 deflection arches 17 Control drive 18 flange 100 inner part 101 Outdoor part 102 support struts 103 Gap seal 104 Annular gap 105 Seal 106 Annular space 108 Axis 140 anteroom S steering axis

Claims

[1] Drive (1) of a watercraft, which is designed as a pump jet and has a housing (10) with at least one inlet channel (14) and at least one outlet nozzle (15) communicating therewith and a propeller arranged between the at least one inlet channel (14) and the at least one outlet nozzle (15) and designed as an impeller (13) and rotatable via a drive motor, by means of which water is sucked into the housing (10) via the inlet channel (14), accelerated and can be ejected from the housing (10) as a thrust jet via the outlet nozzle (15), characterized bythat an outer part (101) of the housing (10) is rotatable about a control axis (S) by means of a control drive and the drive motor comprises an annular stator (11) fastened in the housing (10) and a rotor (12) accommodated therein, which forms the impeller (13), and the housing (10) comprises a fixed inner part (100) and the outer part (101) which is mounted on the inner part (100) so as to be rotatable about the control axis (S), and the stator (11) is fixedly connected to the inner part (100) via retaining struts (102). [2] Drive (1) according to claim 1, characterized by that electrical connection lines of the stator (11) run along or within the support struts (102) from the inner part (100) to the stator (11). [3] Drive (1) according to claim 1 or 2, characterized bythat the inner part (100) delimits a deflection arch (16) for reversing the flow direction of the water sucked in via the inlet channel (14) by the impeller (13) and accelerated in the direction of the at least one outlet nozzle (15), and the holding struts (102) run between the deflection arch (16) and the stator (11). [4] Drive (1) according to one of claims 1 to 3, characterized by that the support struts (102) are shaped in such a way that they counteract a swirl induced in the accelerated water by the impeller (13). [5] Drive (1) according to one of claims 1 to 4, characterized by that the support struts (102) are arranged at equal or different distances from one another. [6] Drive (1) according to one of claims 1 to 5, characterized by that the support struts (102) have the same or different cross-sections. [7] Drive (1) according to one of claims 1 to 6, characterized bythat the outer part (101) comprises the at least one inlet channel (14) and the at least one outlet nozzle (15). [8] Drive (1) according to one of claims 1 to 7, characterized by that the impeller (13) is rotatably mounted on a fixed axis (108) fastened to the inner part (100) or the impeller (13) has an axis projecting in the direction of the inner part (100) which is rotatably mounted on the inner part (100). [9] Drive (1) according to one of claims 1 to 8, characterized by in that, when installed in a hull of the watercraft, it can be moved between a retracted rest position and an extended working position, wherein the drive (1) can be extended in the extended working position to such an extent that the at least one inlet channel (14) and the at least one outlet nozzle (15) protrude beyond the hull of the watercraft. [10] Drive (1) according to one of claims 1 to 9, characterized bythat the inner part (100) is connected to a flange (18) for fixing in the watercraft. [11] Drive (1) according to claim 10, characterized by that the flange (18) is fixed to the watercraft via elastically flexible shock bearings.

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