Underwater drive unit

Abstract

The invention relates to an underwater drive unit (10), preferably for an outboard motor or a pod drive, comprising a plastic housing (1) designed for the flow of water around and a metal housing (2) in which an electric drive (3) is accommodated, wherein the electric drive (3) is accommodated in the metal housing (2) in a manner that is sealed relative to the environment in a watertight manner, and the metal housing (2) is disposed within the plastic housing (1).

Description

TECHNICAL FIELD

[0001] The invention relates to an underwater drive unit comprising a plastic housing designed for the flow of water around it and a metal housing with an electric drive. The invention also relates to a system consisting of at least two such underwater drive units. Furthermore, the invention relates to a ship with such an underwater drive unit. BACKGROUND

[0002] Underwater drive units are usually equipped with an electric drive. The development of electric underwater drive units is subject to a number of competing requirements.

[0003] On the one hand, the drive unit needs to be accommodated in a well thermally conductive material in order to avoid overheating of the electric drive or its power components. For this reason, the drive unit is usually installed in a metal housing. On the other hand, the underwater drive unit must have optimal flow characteristics in order to keep the friction losses as low as possible when flowing around by water. Here, special coatings or at least a particularly good surface quality are often used. Furthermore, the metal housing must be protected from environmental influences, in particular from corrosion which occurs with environmental influences. However, by combining a metal housing with a low water resistance and a protective coating, considerable costs are incurred. This contradicts the other important requirement of cost savings. That is, in the development of underwater drive units, in particular for lower power classes, there is a target conflict between cooling, flow optimization and cost reduction. Furthermore, the design of the underwater drive unit plays a role for marketability. In the prior art, the individual aspects of this target conflict are addressed as a problem.

[0004] EP 2 762 402 A2 discloses a drive unit for a ship, wherein the cooling of the drive unit is achieved by cooling the motor from the inside and the outside.

[0005] US 2004014380 A1 discloses a ship drive with an electric motor in a housing and in addition with a flow opening through which the drive unit can be cooled.

[0006] In US 20070173140 A1 an integrated outboard motor is disclosed which has an electric drive in a plastic housing.

[0007] However, the disadvantage of the solutions known from the prior art is that none of the known teachings achieves a satisfactory solution to the target conflict between cooling, flow optimization and cost savings. According to the prior art, either the housing is made of metal, whereby a costly and expensive finishing must be carried out, or the housing is made of plastic, whereby the cooling of the electric drive is not optimal. SUMMARY

[0008] Based on the known prior art, it is the object of the present application to provide an improved underwater drive unit.

[0009] The object is achieved by an underwater unit having the features of the present application. Advantageous refinements emerge from the description and the drawings.

[0010] Correspondingly, an underwater drive unit, preferably for an outboard motor or a pod drive, is proposed, comprising a plastic housing and a metal housing designed for the flow-through of water, in which an electric drive is accommodated. According to the application, the electric drive is arranged in the metal housing in a manner that is sealed against the environment and the metal housing is arranged in the plastic housing.

[0011] The metal housing is waterproof and arranged within the plastic housing, in this way, a separation of the functions "cooling of the electric drive" and "flow optimization" is achieved. In other words, the "housing-in-housing" principle, i.e. the principle "metal housing in plastic housing", is used.

[0012] The function "cooling of the electric drive" is achieved here by means of the metal housing, which has good heat conduction properties and thus effectively transports heat from the electric drive to the medium, water or plastic material, which surrounds the metal housing.

[0013] The function "flow optimization" is achieved here by means of the plastic housing, which can be simply and flexibly shaped in any way that is optimal for the respective application case of the underwater drive unit. In particular, by using the plastic housing, expensive measures for corrosion protection and for flow-optimized coatings can be avoided compared to the metal housing and the manufacturing costs are reduced.

[0014] As a result, the metal housing does not have to have any flow-optimized properties and special innovative design solutions and can be provided with a simple material surface, so that the metal housing can be constructed particularly easily. Thereby, the metal housing can provide an untreated surface as far as possible. The metal housing can also be equipped with a simple shape, for example a cylindrical shape.

[0015] At the same time, the plastic housing does not have to have sealing properties. Therefore, the plastic housing can be designed only with regard to the requirements of the flow-technical aspect.

[0016] Thus, the target conflict between cost savings, flow optimization and cooling is optimally solved by an underwater drive unit comprising a plastic housing designed for the flow around by water and a metal housing with an electric drive, wherein the metal housing is waterproof and arranged in the plastic housing. Furthermore, due to the corrugated region provided by the plastic housing, the metal housing is protected from mechanical energy inputs, such as can occur in the case of contact with the ground, from damage, in particular from water damage, which can lead to complete destruction of the motor and electronics. Furthermore, due to the plastic housing, additional protection of the metal housing from environmental influences can be dispensed with.

[0017] For the present disclosure, the underwater unit is a pylon of an outboard motor or pod, which is completely or partially below the water surface in the rated operation of the underwater drive unit.

[0018] For the present disclosure, the plastic housing can be understood as a housing with plastic. In particular, it can be understood as a housing manufactured from one or more plastics or composite materials only. The plastic housing can be coated or uncoated. In particular, the plastic housing can be painted. Alternatively or additionally, the plastic housing can have a surface embossing. Preferably, the surface embossing can be configured such that the friction is reduced when the plastic housing is flowed around by water.

[0019] For the present disclosure, the metal housing can be understood as a housing with metal. In particular, it can be understood as a housing manufactured from metal only. For example, the housing can comprise a casting. Advantageously, the metal housing has an untreated surface. Thereby, cost savings can be achieved.

[0020] Thus, the term "waterproof" is understood as meaning that, in the rated operation of the underwater drive unit, no water or only negligible amounts of water can penetrate into the metal housing.

[0021] Preferably, the electric drive of the underwater drive unit is designed for one of the lower power classes of the underwater drive unit, in particular as an electric drive with a power of 0.2 PS to 80 PS, for example between 0.2 and 0.7 PS, 1 and 3 PS, 1.5 and 3 PS, 5 and 20 PS or 40 and 80 PS (approximately 150 W to 500 W, 730 W to 2.2 kW, 1.1 kW to 2.2 kW, 3.6 kW to 14.7 kW or 29.4 kW to 58 kW). This has the advantage that with an underwater drive unit as disclosed herein, particularly high cost savings can be achieved in this power class.

[0022] Advantageously, the plastic housing has an opening connected via a flow channel, wherein the plastic housing is configured such that, in the flowed-around state of the plastic housing, at least a part of the metal housing is flowed around.

[0023] The plastic housing has openings which are connected via flow channels, and the plastic housing is designed in such a way that, in the state of being flowed around by the plastic housing, at least a part of the metal housing is flowed around, in this way it is possible to cool the metal housing, in particular, particularly effectively. A cladding of the metal housing is not necessary here, since the metal housing is not part of the outer structure and does not have to fulfill a flow-optimized function. Thus, the metal housing does not have to fulfill any special flow-technical requirements. At the same time, the metal housing also does not have to fulfill any aesthetic requirements, since it is not visible from the outside or only barely visible.

[0024] In the state of being flowed around by the plastic housing, at least a part of the metal housing is flowed around, in this way, cooling of the metal housing and thus of the drive components arranged therein can take place during operation.

[0025] For the purposes of the present disclosure, a plastic housing flowed around by water means a housing which has a plastic and a configuration, in particular an outer contour, which is optimized in terms of being flowed around by water.

[0026] Advantageously, the plastic housing comprises at least one inlet in the front region and at least one outlet in the rear region, wherein the flow channel extends along the longitudinal axis L of the underwater drive unit. In other words, water which is flowed around during operation of the underwater drive unit can thus enter the plastic housing via the inlet, reach the metal housing via the flow channel and then exit the plastic housing via the outlet. In this way, continuous flowing around of the metal housing can be achieved, whereby optimal cooling of the drive components is provided during operation.

[0027] Advantageously, the flow channel is at least partially formed by the metal housing. In other words, the metal housing forms at least one boundary or wall section of the flow channel. The flow channel is at least partially formed by the metal housing, in this way, in the state of being flowed around by the plastic housing, water comes into contact with the metal housing via the flow channel. The heat transfer between the metal housing and the water is optimized by the wetting of the water, whereby the cooling effect is further improved.

[0028] Advantageously, the plastic housing is connected with the column tube, wherein the connection takes place via a column tube molding. The plastic housing is connected with the column tube, in this way, the metal housing does not have to be welded or formed on the column tube. Compared to established manufacturing methods, such as welding the column tube to the metal housing or forming the column tube connection to the metal housing as a casting, the manufacturing costs can be greatly reduced, since some production steps, such as twisting, drilling, welding or casting and mechanical finishing, are saved. Furthermore, connecting the column tube with the plastic housing enables greater design freedom for the design concept of the plastic housing as well as the metal housing.

[0029] However, the column tube can also be connected directly to the metal housing, for example welded, riveted or screwed thereto, or formed in one piece with the metal housing. By connecting the column tube directly to the metal housing, a further improved structural strength can be achieved. The plastic housing can likewise be connected to the column tube here, for example via the already mentioned molding.

[0030] However, the plastic housing can also be held only on the metal housing, which is connected to the column tube as such. In this design, the plastic housing can have a simple opening in the passage region of the column tube, through which the column tube is guided without the plastic housing having to be further secured.

[0031] Advantageously, the electric drive comprises an electric motor, optionally an electric drive comprising a transmission and / or electronic components, and drives the propeller via a drive shaft. The mentioned components are then accommodated in the metal housing in a manner sealed relative to the environment, in a watertight manner. By means of the electric motor, a torque for driving the drive shaft can be provided. Optionally, a torque acting on the drive shaft via the transmission can be converted into another torque / speed ratio.

[0032] The electric drive comprises an electric motor, a transmission and / or electronic components, by means of which all components required for driving the propeller via the drive shaft can be cooled via the metal housing, which is at least partially surrounded by water in the state of being surrounded by the plastic housing. Thus, the entire motor unit is accommodated in the metal housing, which is likewise at least partially surrounded by water in the state of being surrounded by the plastic housing and thus cooled.

[0033] Advantageously, the metal housing is formed by a cylindrical metal tube, which comprises a front tube seal at its front end and / or a rear tube seal at its rear end. Thus, the metal housing can be made from a simple tube, which is sealed at both ends with a cover. In particular, the tube seal at the rear end can also be part of the metal housing, i.e. formed in one piece with the metal housing.

[0034] Advantageously, the metal housing has a cable seal for sealing off an electric cable at its front end and / or an axle seal at its rear end. Thereby, it can be ensured that the electric cable and / or the drive shaft are guided out of the metal housing, while water cannot enter the metal housing via these interfaces. For example, the electric cable can be guided out of the metal tube by means of a suitable, sealed screwing. The use of the cable seal and / or the axle seal makes it possible to accommodate the entire motor unit in the plastic housing, so that a surrounding of at least a part of the metal housing by water is possible without water penetrating into the metal housing.

[0035] Advantageously, the plastic housing has a plurality of flow channels. The advantage of having a plurality of flow channels on or in the plastic housing is that the metal housing arranged in the plastic housing can be more uniformly or more specifically flowed around and thus can be cooled correspondingly better. Furthermore, this has the advantage that frictional losses that can be caused by the water entering the plastic housing can be distributed uniformly over the plastic housing. As a result, it is thereby possible to avoid undesirable rolling moments, yawing moments or pitching moments on the plastic housing during operation of the underwater drive unit.

[0036] Preferably, the flow channels of the plastic housing can have elevations on the plastic housing, thereby increasing the effective gap between the plastic housing and the metal housing. Thereby, the inflow of water to the metal housing can be increased and the pressure losses occurring there can be reduced. Nevertheless, the elevations can act as longitudinally extending flow guide elements, thereby optimizing the stability of the underwater drive unit during travel.

[0037] Advantageously, the flow channels are separated from one another via longitudinal ribs, wherein the longitudinal ribs also fix the metal housing and the plastic housing to one another. Thereby, it can be ensured that the metal housing is simply and safely arranged in the plastic housing. Furthermore, it is possible to configure the flow channels thus defined via which a predefined flow around the metal housing can be ensured. Thus, the cooling of the metal housing can be optimized during operation of the underwater unit. In other words, by this means, fluid-dynamically induced flow losses can be reduced during operation, thereby enabling effective cooling of the metal housing.

[0038] Advantageously, the flow channels open into separate inlets and / or outlets in the plastic housing, respectively. Thereby, the inlets and / or outlets can be matched to the geometry of the respective flow channel in a targeted manner. For example, the inlets can have a rectangular cross section with rounded corners. Alternatively, the outlets can have a substantially oval cross section. By this means, fluid-dynamically induced flow losses can be reduced during operation, thereby enabling effective cooling of the metal housing.

[0039] According to an alternative embodiment, the flow channels open into a common inlet distributor and / or outlet distributor having a common inlet or outlet. By this means, fluid-dynamically induced flow losses can be further reduced, thereby enabling effective cooling of the metal housing.

[0040] It is preferred that the metal housing is arranged substantially centrally in the plastic housing, wherein the plastic housing preferably has a cable guide channel between the metal housing and the plastic housing. By arranging the metal housing substantially centrally in the plastic housing, it is possible to achieve that the flow channels are arranged uniformly along the circumference of the plastic housing. Furthermore, it is possible to ensure that the metal housing is protected from mechanical energy inputs from all sides by the plastic housing, for example in the event of a collision or contact with the ground.

[0041] It is preferred that the openings and / or the flow channels have a rigid or variable flow restriction, by means of which the flow through the flow channels can be set. By using a rigid or variable flow restriction in the openings and / or the flow channels, it is possible to set a targeted delivery of water around the metal housing. In this way, the cooling of the metal housing can be changed not only in relation to the speed, but also via a further set variable. As a result, the cooling of the metal housing and the drive components arranged therein can be further improved.

[0042] It is advantageous if the openings and / or the flow channels have a spoiler, wherein the spoiler is preferably connected to the metal housing. The openings and / or the flow channels have a spoiler in this way, the heat transfer between the metal housing and the water flowing around the metal housing can be significantly improved. In other words, the proportion of turbulent flow is increased by the spoiler, thereby facilitating heat transfer. This is provided in particular when the spoiler is connected to the metal housing. In this case, both the proportion of turbulent flow in the fluid and the surface area of the metal housing provided for heat transfer are increased. As a result, particularly effective cooling of the metal housing can be achieved. According to an advantageous refinement, the spoiler is designed in such a way that, despite the generation of turbulence, the resulting pressure loss is as low as possible. As a result, effective cooling can be achieved without a significant impact on the flow losses.

[0043] The underwater drive unit can be connected, for example, to a column of an electric outboard motor, wherein on the upper side of the column either a control unit with an integrated battery pack and a rudder can be arranged, in particular, or a control unit with a rudder machine but without its own battery pack can be arranged. The column of the outboard motor can here likewise be composed of a simply designed metal tube or plastic tube, which is surrounded by a plastic housing.

[0044] The underwater drive unit can also be arranged in a hull drive, which is arranged exclusively underwater.

[0045] In a preferred refinement, the column tube is directly connected, preferably welded and / or screwed and / or riveted, to the metal housing and / or is composed in one piece with the metal housing.

[0046] In terms of the system, according to the present disclosure, the object is furthermore achieved by a system composed of at least two underwater drive units. The at least two underwater drive units of the system have identically structured electric drives and / or identically structured metal housings, wherein each electric drive is preset to a specific, different power class, and wherein at least one dimension of the plastic housing is selected in accordance with the preset power class.

[0047] In other words, the system is a product series or product combination. The individual different power classes can be set to their respective power class, for example, via power electronics.

[0048] By identically structured electric drives and / or metal housings, identical components can be installed across products, thereby enabling cost savings. At least one dimension of the plastic housing is selected in accordance with the preset power class, in this way, on the one hand, a physically necessary or advantageous adaptation of the plastic housing can be made. On the other hand, a visually distinctive feature is thereby also achieved, which enables conclusions to be drawn about the preset power class or enables a visual differentiation of the individual preset power classes. An improved marketing of the products can thereby be achieved.

[0049] In terms of the present disclosure, a preset power class refers to a power upper limit that is fixedly set on the manufacturer's side and cannot be arbitrarily changed by the end user without in-depth manipulation of the underwater drive unit, for example, by means of chip tuning or the like.

[0050] For example, at least two of the five power classes mentioned here can be preset, such as 0.2 to 0.7 PS, 1 to 3 PS, 1.5 to 3 PS, 5 to 20 PS, or 40 to 80 PS. The drives suitable for at least two of the power classes mentioned can have approximately the same power electronics, the same metal housing, and the same electric drive. In particular, one of the possible power classes can then be set by setting the power electronics, for example, by means of a switch or a jumper, or by programming or activating the drive control.

[0051] In other words, drives of different power classes can be provided by the same hardware. However, for different power classes, differently designed plastic housings can be selected, respectively, so that the dimensions and shape of the housing can be matched to the protection requirements and the required flow characteristics and, in particular, to the heat dissipation requirements of the respective selected power class.

[0052] For example, in underwater drive units of the 0.2 to 0.7 PS class, a small pleated area and a low cooling power are sufficient, so that the plastic housing can be designed small. In underwater drive units of the 40-80 PS class, however, a large pleated area and a high cooling power are required, so that the plastic housing can be designed larger and, in particular, also more robustly. In particular, the wall thickness of the plastic housing can be increased. Furthermore, the flow properties of the plastic housing of the 40-80 PS class can be matched to the greater achievable speed and the greater possible acceleration.

[0053] Advantageously, the first underwater drive unit is preset to a higher power class than the second underwater drive unit, wherein the plastic housing of the first underwater drive unit has a larger cross section and / or a larger length than the plastic housing of the second underwater drive unit.

[0054] In this way, it can be ensured that the first underwater drive unit having the higher power class has a locally increased distance between the plastic housing and the metal housing, whereby the heat transfer between the plastic housing and the metal housing can be optimized. Ultimately, the operating safety of the underwater drive unit can thereby be improved. In this way, it can also be achieved that the first underwater unit having the higher power class has a larger appearance than the second underwater drive unit, whereby a purely visually recognizable indication of the higher power class can be achieved.

[0055] The object is furthermore achieved by a ship having an underwater drive unit. BRIEF DESCRIPTION OF DRAWINGS

[0056] Preferred further embodiments of the present application are set forth in the following description of the drawings. Herein shown are:

[0057] Figure 1 a schematic sectional view of an underwater drive unit according to a first embodiment shown in a sectional plane extending along a longitudinal direction of the underwater drive unit is shown;

[0058] Figure 2 a detailed sectional view of an underwater drive unit according to a further embodiment in a sectional plane extending along a longitudinal direction of the underwater drive unit is shown;

[0059] Figure 3 a schematic sectional view of an underwater drive unit according to a further embodiment in a sectional plane oriented perpendicular to a longitudinal axis of the underwater drive unit is shown; Figure 2

[0060] Figure 4 a schematic sectional view of an underwater drive unit according to a further embodiment in a sectional plane extending along a longitudinal direction of the underwater drive unit is shown;

[0061] Figure 5 a schematic sectional view of an underwater drive unit according to a further embodiment in a sectional plane extending along a longitudinal direction of the underwater drive unit is shown;​Figure 4 perspective view of the underwater drive unit in

[0062] Figure 6 a schematic view of the underwater drive unit is shown, in which the column tube is connected with the metal housing. DETAILED DESCRIPTION

[0063] In the following, a preferred embodiment is described with reference to the drawings. Herein, identical, similar or identically acting elements are provided with the same reference signs in the different figures and are partially not described again in order to avoid redundancy.

[0064] In Figure 1 a schematic sectional view of the underwater drive unit 10 according to the first embodiment is shown, which is shown in a simplified manner. The underwater drive unit 10 is depicted in a sectional plane which extends along a longitudinal direction L of the underwater drive unit. The underwater drive unit 10 comprises a plastic housing 1 which is designed for the flow-through of water and a metal housing 2 which is arranged in the plastic housing 1, in which the electric drive 3 is accommodated.

[0065] The metal housing 2 is configured to be watertight and accommodates the electric drive 3. The metal housing 2 is in turn completely arranged within the plastic housing 1. Thus, the "housing-in-housing" principle, i.e. the "metal housing in plastic housing" principle, is used. The outer housing, i.e. the plastic housing 1, fulfills a flow-optimizing function here, since the plastic housing 1 is flowed through by water in the operation of the underwater drive unit 10. The inner housing, i.e. the metal housing 2, fulfills a cooling function of the metal housing 2 and thus of the electric drive 3 here. The metal housing 2 is untreated and is produced in such a way that no substantial surface treatment is carried out.

[0066] The plastic housing 1 is connected with a column tube 6. The connection of the column tube 6 with the plastic housing 1 takes place via a column tube molding 7. In this case, the column tube 6 does not have to be sealed. The underwater drive unit 10 can be connected with a not shown ship via the column tube 6. The propulsion of the underwater drive unit 10 is generated in that the electric drive 3 in the metal housing 2 drives a drive shaft 8 on which a propeller 9 is mounted.

[0067] Figure 2 a detailed sectional view of the underwater drive unit 10 according to a further embodiment is shown in a sectional plane which extends along a longitudinal direction of the underwater drive unit 10. The plastic housing 1 has an opening 4 which is connected via a flow channel 5. The plastic housing 1 is configured in such a way that a flow-through of at least a part of the metal housing 2 takes place in the flowed-through state of the plastic housing 1.

[0068] The opening 4 comprises an inlet 4' which is formed in the front region of the plastic housing 1 and an outlet 4" which is formed in the rear region of the plastic housing 1. Between the inlet 4' and the outlet 4", the flow channel 5 extends substantially along the longitudinal axis L of the underwater drive unit 10.

[0069] The flow channel 5 of the underwater drive unit 10 is partially formed by the metal housing 2. This means that, in the flow-through state of the plastic housing 1, water reaches the metal housing 2 via the inlet 4' of the flow channel 5 and wets it. Via the water and the active surface of the metal housing, a heat transfer between the metal housing 2 and the water which is flowing around is facilitated. The metal housing 2 is watertight.

[0070] The plastic housing 1 is connected with a column tube 6. The connection of the column tube 6 with the plastic housing 1 takes place via a column tube molding 7. In this case, the column tube 6 does not have to be sealed. The underwater drive unit 10 can be connected with a not shown ship via the column tube 6. The propulsion of the underwater drive unit 10 is generated in that the electric drive 3 in the metal housing 2 drives a drive shaft 8 on which a propeller 9 is mounted.

[0071] In Figure 2 The underwater drive unit 10 shown in Fig. 1 has two flow channels 5. Correspondingly, the underwater drive unit 10 has two inlets 4' and two outlets 4". The inlets 4 and the outlets 4" are each formed as separate openings 4 in the plastic housing 1.

[0072] According to the depiction in Figure 2 The metal housing 2 has, according to the depiction in Fig. 2, a metal tube 60 which has a front tube seal 61 at the front end and a rear tube seal 62 at the rear end thereof. The metal tube 60 is a simple, untreated metal tube. The front tube seal 61 and the rear tube seal 62 can each be understood as a cover. The metal tube 2 is sealed by the covers to prevent water from entering. The covers can be connected with the metal tube 60 via a threaded connection, in particular via a flange, if necessary additionally by means of a suitable seal. Furthermore, the metal housing 2 has a cable seal 63 at the front end thereof and an axle seal 64 at the rear end thereof. In a specific embodiment, the cable seal 63 is arranged on the front tube seal 63 and the axle seal 64 is arranged on the rear tube seal 62.

[0073] Via the cable seal 63 arranged in the front tube seal 61 of the metal housing 2, a cable 65 is guided from the metal housing 2 into a cable guide channel 50 in a manner sealed against the entry of water. Subsequently, the cable 65 is guided from the cable guide channel 50 into the column tube 6 at the column tube molding 7.

[0074] The electric drive 3 can here comprise i) a motor, ii) a motor with a transmission, iii) a motor with electronics, and iv) a motor with a transmission and electronics.

[0075] Figure 3 A schematic cross-sectional view of the underwater drive unit 10 according to the embodiment shown in Figure 2 Fig. 1 in a cross-sectional plane A-A oriented perpendicular to the longitudinal axis L and stretching through the tube seal 61 of the front portion is shown.

[0076] Accordingly, the underwater drive unit 10 is shown in Figure 3 Fig. 1 comprising a plastic housing 1 designed for being flowed around by water and a metal housing 2 arranged in the plastic housing 1 and an electric drive 3 not shown. The plastic housing 1 has here a plurality of flow channels 5 separated from each other via longitudinal ribs 20. The longitudinal ribs also fix the metal housing 2 and the plastic housing 1 on each other. Here, the metal housing 2 is arranged substantially centrally in the plastic housing 1. Furthermore, the plastic housing 1 has a cable guide channel 50 between the metal housing 2 and the plastic housing 1.

[0077] Via a cable seal 63 arranged in a tube seal 61 of a front portion of the metal housing 3, a cable 65 is guided from the metal housing 2 into the cable guide channel 50 in a manner sealed against water ingress. Subsequently, the cable 65 is guided from the cable guide channel 50 into a column tube 6 at a column tube molding 7.

[0078] Figure 4 A schematic cross-sectional view of the underwater drive unit 10 according to another embodiment in a cross-sectional plane extending along the longitudinal direction 11 is shown. Correspondingly, Figure 4 The drawing in Fig. 1 shows an underwater drive unit 10 comprising a plastic housing 1 designed for being flowed around by water and a water-tight metal housing 2 arranged in the plastic housing 1 and an electric drive 3. The plastic housing 1 has a plurality of flow channels 5 each extending between an individual inlet 4 and an individual outlet 5. The plastic housing 1 is here constructed such that in a flowed-around state of the plastic housing 1 a flow around at least a portion of the metal housing 2 takes place. In a specific example, the flow around of the metal housing 2 is achieved by a flow through the respective flow channels 5. Here, the respective flow channel 5 is partially constituted by the metal housing 2. In the flowed-around state of the plastic housing 1, the water flowing around wets an outer side of the metal housing 2.

[0079] The plastic housing 1 is connected with a column tube 6, wherein the connection takes place via a column tube molding 7. The electric drive 3 of the underwater drive unit comprises an electric motor 31, a transmission 30, and electronic components and drives a propeller (not shown) via a drive shaft 8.

[0080] The metal housing 2 of the underwater drive unit 10 has a cable seal 63 (not shown) for sealing the cable 65 at its front end and a shaft seal 64 at its rear end. Here, the cable seal 63 is arranged on the front tube seal 61 which is arranged at the front end of the metal tube 60. The shaft seal 64 is arranged on the rear tube seal 62 which is arranged at the rear end of the metal tube 60.

[0081] The inlet 4' has a substantially rectangular cross section with rounded edges. The outlet 4" has a substantially oval cross section. In this way, flow losses caused by fluid mechanics can be reduced, thereby enabling an effective cooling of the metal housing 2.

[0082] Figure 5 A perspective view of the underwater drive unit 10 is shown in Figure 4 From this view it can be seen that the individual flow channels 5 of the underwater drive unit 10 have a bulge. In other words, the plastic housing 1 has a bulge. The respective inlet 4' and outlet 4" are formed here at the beginning and at the end of each bulge.

[0083] Figure 6 A variant of the underwater drive unit 10 is shown in Figure 1 which differs here in that the column tube 6 is directly connected with the metal housing 2. In the shown embodiment, the connection is provided by a weld 22 of the column tube 6 with the metal housing 2.

[0084] However, the direct connection between the column tube 6 and the metal housing 2 can also be realized by screwing or riveting. In another embodiment, the column tube 6 can be formed in one piece with the metal housing 2.

[0085] In the mentioned variant, the plastic housing 1 can also be connected with the column tube 6, as shown in Figure 6 Here, a column tube molding 7 is also provided for connecting the plastic housing 1 with the column tube 6.

[0086] However, the plastic housing 1 can also be arranged not to be in contact with the column tube 6 when there is a direct connection between the column tube 6 and the metal housing 2. For example, the column tube 6 can be guided only through an opening of the plastic housing 1.

[0087] All individual features explained in the embodiments can be combined and / or interchanged, as far as applicable, without leaving the scope of the present invention.

[0088] List of reference signs

[0089] 1 plastic housing

[0090] 2 metal housing

[0091] 3 electric drive

[0092] 4 opening

[0093] 4' inlet

[0094] 4" outlet

[0095] 5 flow channel

[0096] 6 column tube

[0097] 7 column tube molding

[0098] 8 drive shaft

[0099] 9 propeller

[0100] 10 underwater drive unit

[0101] 20 longitudinal rib

[0102] 22 weld

[0103] 30 transmission

[0104] 31 electric motor

[0105] 50 cable guide channel

[0106] 60 metal tube

[0107] 61 front tube seal

[0108] 62 rear tube seal

[0109] 63 cable seal

[0110] 64 shaft seal

[0111] 65 cable

Claims

1. An underwater drive unit (10), comprising a plastic housing (1) designed for the flow of water around it and a metal housing (2) in which an electric drive (3) is accommodated, characterized in that the electric drive (3) is accommodated in the metal housing (2) in a manner sealed against the environment, and the metal housing (2) is arranged within the plastic housing (1), wherein the plastic housing (1) has an opening (4) which is connected via a flow channel (5), wherein the plastic housing (1) is designed in such a way that at least a part of the metal housing (2) is flowed around in the state of the plastic housing (1) being flowed around, wherein the opening (4) and / or the flow channel (5) has a flow spoiler which is connected with the metal housing (2) in such a way that the proportion of turbulent flow is increased by the flow spoiler.

2. The underwater drive unit (10) according to claim 1, characterized in that The plastic housing (1) comprises an inlet (4') in the front region and an outlet (4'') in the rear region, and the flow channel (5) extends along a longitudinal axis (L) of the underwater drive unit (10).

3. The underwater drive unit (10) according to claim 1 or 2, characterized in that The flow channel (5) is at least partially delimited by the metal housing (2).

4. The underwater drive unit (10) according to claim 1 or 2, characterized in that The plastic housing (1) is connected with a column tube (6).

5. The underwater drive unit (10) according to claim 1 or 2, characterized in that The electric drive (3) comprises an electric motor (31) and / or electronic components and drives a propeller (9) via a drive shaft (8).

6. The underwater drive unit (10) according to claim 1 or 2, characterized in that The metal housing (2) has a metal tube (60) which comprises a front tube seal (61) at the front end and / or a rear tube seal (62) at the rear end thereof.

7. The underwater drive unit (10) according to claim 6, characterized in that The metal housing (2) has a cable seal (63) for sealing a cable (65) at the front end thereof and / or a shaft seal (64) at the rear end thereof.

8. The underwater drive unit (10) according to claim 1 or 2, characterized in that The plastic housing (1) has a plurality of flow channels (5).

9. The underwater drive unit (10) according to claim 8, characterized in that The flow channels (5) are separated from one another via longitudinal ribs (20), wherein the longitudinal ribs (20) additionally fix the metal housing (2) and the plastic housing (1) to one another.

10. The underwater drive unit (10) according to claim 8, characterized in that The flow channels (5) each open into separate inlets (4') and / or outlets (4'') in the plastic housing (1).

11. The underwater drive unit (10) according to claim 7, characterized in that The flow channels (5) open into an inlet distributor and / or outlet distributor having a common inlet or outlet.

12. The underwater drive unit (10) according to claim 1 or 2, characterized in that The metal housing (2) is arranged substantially centrally in the plastic housing (1).

13. The underwater drive unit (10) according to claim 1 or 2, characterized in that The opening (4) and / or the flow channel (5) has a rigid or variable flow restriction mechanism by means of which the flow rate through the flow channel (5) can be set.

14. The underwater drive unit (10) according to claim 4, characterized in that The column tube (6) is connected directly with the metal housing (2), and / or the column tube (6) is formed in one piece with the metal housing (2).

15. The underwater drive unit (10) according to claim 1, characterized in that The underwater drive unit (10) is used for an outboard motor or a pod drive.

16. The underwater drive unit (10) according to claim 4, characterized in that The connection is made via a column tube molding (7).

17. The underwater drive unit (10) according to claim 12, characterized in that The plastic housing (1) has a cable guide channel (50) between the metal housing (2) and the plastic housing (1).

18. The underwater drive unit (10) according to claim 14, characterized in that The column tube (6) is welded and / or screwed and / or riveted with the metal housing.

19. The underwater drive unit (10) according to claim 1, characterized in that In the state of flow around the plastic housing (1), the water flowing around wets the outer side of the metal housing (2).

20. The underwater drive unit (10) according to claim 5, characterized in that The electric drive (3) comprises a transmission (30).

21. A system of at least two underwater drive units (10) according to any of the preceding claims, characterized in that, At least two of the underwater drive units (10) have electric drives (3) of identical construction and / or metal housings (2) of identical construction, wherein each electric drive (3) is preset to a certain, different power rating, and wherein at least one dimension of the plastic housing (1) is selected in accordance with the preset power rating.

22. The system of at least two underwater drive units (10) according to claim 21, characterized in that The first underwater drive unit is preset to a higher power rating than the second underwater drive unit, wherein the plastic housing (1) of the first underwater drive unit has a larger cross section and / or a larger length than the plastic housing (1) of the second underwater drive unit.

23. A ship having an underwater drive unit (10) according to any one of the preceding claims 1 to 20.

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